world's first airline with electric-only aircraft

RobertDyck · 2019-03-26 20:17:20

Harbour Air to become the world's first airline with electric-only aircraft

Harbour Air is set to become the world’s first airline with an all-electric fleet.
The short-haul seaplane airline announced today it has partnered with Redmond, Washington-based magniX to convert its fossil fuel-powered seaplanes into an electric fleet powered by the magni500 — a 750 horsepower all-electric motor.
The first aircraft to undergo the conversion will be the DHC-2 de Havilland Beaver, which is a six-passenger aircraft used across Harbour Air’s network. The first flight tests of this aircraft with the all-electric motor is slated for the end of this year.
...
Harbour Air sees over 500,000 passengers on 30,000 commercial flights annually, with 12 operating routes including from Vancouver to Seattle, Vancouver to Victoria, and Vancouver to Nanaimo.

I didn't know this was possible.

Terraformer · 2019-03-27 03:39:39

Where do electric planes make sense, versus other modes of travel (e.g. trains)?

It seems to me that it would be where there are distances short enough for the planes to make it; geography (both natural and human!) that makes alternatives impractical; and infrastructure available such that it makes sense to transition to electricity. Unfortunately, a lot of places that would fit the first two would fail on the third (Alaska, Hawaii etc), generating a lot of their power from diesel generators.

If they get to ~1000km range, though, island hopping across the Atlantic becomes possible. Scotland-Iceland-Greenland-Labrador...

kbd512 · 2019-03-27 04:17:04

Robert,

If people are still waiting for better batteries to become available to deliver sufficient energy density, then it's not possible. If those people could rewire their battery-happy brains to accept that fuel cells are required for some applications, then it's possible within a few years.

Intelligent Energy (UK) makes a fuel cell that delivers 100kWe and weighs 33kg. For this application, we need 6 of them and that's 198kg.

Magnix (US and AUS) makes a Magni500 560kW motor that weighs 120kg (6.25kW/kg).

Magnax (Belgium) makes a AXF275 300kW motors that weigh 24kg (12.5kW/kg). For this application, we need 2 of them and that's 48kg.

Pratt & Whitney Canada makes 750hp PT-6A-25C turboprops that weigh 153kg.

Although we still can't best the Pratt on power-to-weight, when combined with its fuel as a complete propulsion system, we can best it on fuel consumption and therefore weight. For those of us who wish to remain airborne, weight is our mortal enemy. The PT6A's SFC numbers look pretty good until you understand that its quoted SFC number is at maximum rated output, which is only used during takeoff and initial climb. At a cruise power setting, especially at low altitude where sea planes spend their entire lives, we can take that 0.67lb/hp/hr figure and almost double it. If you can climb to 10,000ft, plan on about 59gph or 182kg/hr or 401lbs/hr. You're gonna burn more than that climbing for altitude, but let's keep things simple. Yes, I'm well aware that it'll be more than that with the climb, start-up, taxi to the designated take-off / landing area (even on water specific areas are designated as "runways" to avoid boats and submerged debris), etc.

Intelligent Energy's fuel cells are ~70% efficient, but let's assume there are other factors at play here and we're operating at 60% efficiency in the real world. We need around 42.3g of H2 per kWh generated. 420kW is 75% of our power output. That works out to 17.7kg of H2 per flight hour. If our fuel is liquid Anhydrous Ammonia (LNH3), that works out to 100kg of LNH3, which is 19.7 gallons per hour. We'll assume that we'll use Toyota's plasma cracker to feed pure H2 from LNH3 into the fuel cell.

Assuming they're using the 120kg Magnix motor and 198kg worth of fuel cells to provide takeoff power, the weight penalty is 83kg. If the flight lasts for 2 hours or other factors dictate that we take off with at least 2 hours of fuel onboard to divert or come back home, then the weight is a wash. If the flight lasts longer than 2 hours of flight, then the fuel cells rapidly illustrate their potential weight savings.

PP = Power Plant
FC-EM = Fuel Cell and Electric Motor

PP PT6A FC-EM Weight Diff
1hr 335kg 418kg +83kg
2hr 517kg 518kg +1kg
3hr 699kg 618kg -81kg
4hr 881kg 718kg -163kg

Jet-A is $4.65 per gallon, nationwide average, over the 3,862 FBO's surveyed. LNH3 is about $1.25 per gallon at retail. That's $1,095 for 4 hours worth of Jet-A or $217 for 4 hours worth of LNH3. Think about what that would do to ticket prices. Fuel is the most significant operating expense for the operators. Even if the LNH3 was made from LNG, emissions would still be drastically reduced if all of our turboprops were converted to use fuel cells.

Intelligent Energy is now working on a 5kW/kg PEM fuel cell. That would make the weight differential a wash from the 1st hour of flight and an improvement every hour thereafter. If the Magnax, vs Magnix, motors were used with a magnetic gearbox, then the weight advantage goes to the fuel cell powered aircraft from the word "go".

The best part is that you can actually have a conversation in the cockpit without using a headset and the vibrations are so drastically reduced that the fatigue life of the airframe increases. People on the ground can have a conversation next to the aircraft when the engine is running, so long as it's not running at full power. Even if it's running at full power, you'll have to get within a few yards for the noise to be irritating. That said, there's no need to have the engine running unless you're actively taxiing. If ATC tells you to "line up and wait", then you don't need the engine running. If you had electric motors in the gear, then you could taxi without running the engine at all and reduce the potential for prop strike on obstructions / ground crew / ground vehicles / birds. Thus far, no aircraft have motors in the gear. That said, they're so light and small now that they could.

How does this relate to something you'd know and use?

A DHC-3T Otter equipped with the 750hp PT6A-135 and enlarged tanks has about 4 hours of fuel onboard. It'd be lighter and cheaper to fly at lower altitudes using more efficient electric motors and fuel cells.

When Iron Nitride permanent magnets and CNT wiring makes its debut in electric motors, we'll easily surpass 25kW/kg without resorting to using superconductors. We're already at 15kW/kg with NdFeB and Copper. Magnax is already running their motors at 98% efficiency. My take on this is that some waste heat is a desirable thing to have to use to heat the leading edges of the air intake, wings, and empennage to inhibit ice formation. Raptor Aircraft is using waste heat from their turbo diesel to heat the leading edges. As long as you can dump the waste heat into different parts of the airframe that should be heated, it's a good idea to have some waste heat. The cabin also needs to be heated. As it stands, Magnax would only provide a maximum of 11.2kWt to do that. The fuel cells are evaporatively cooled, but don't get hot enough to adequately heat the leading edges.

SpaceNut · 2019-03-27 16:17:44

The hydrogen fuel cell to get the most power out of it requires pure oxygen as well which means more mass for equipment and energy to purify for use.

kbd512 · 2019-03-27 16:37:49

Robert,

Lest anyone think I'm opposed to using batteries where appropriate, there are some cases where batteries make more sense than any other form of power. Britain has certain daily or twice daily very short range ferry flights. Using Lithium-ion makes more sense than burning lots of Jet A or the added hassles of fuel handling for fuel cells, for example.

So, let's take a look at what battery energy density buys in rough terms of flight time.

At 250Wh/kg, you get 1 hour of flight time with roughly equivalent weight (to a plane with a Continental or Lycoming 4 to 8 cylinder engine).

At 500Wh/kg, you get 2 hours of flight time with roughly equivalent weight.

At 2,500Wh/kg, you get gasoline-equivalent performance. However, that is 1 order of magnitude above where presently we're at.

Aluminum-Air batteries are technically at 1,300Wh/kg, but those batteries have to have their electrolytes recycled every month or possibly every week for an aircraft application. The electrolyte is dirt cheap and easy to recycle by reversing the redox reaction, but it has to be done. Their power density is not quite as high as Lithium-ion, as I understand it, so you need more capacity or some other "in conjunction with" technology like super capacitors to provide the surge of power required for take off.

We're also assuming the use of lightweight composite airframe materials such as carbon fiber and fiberglass, rather than heavier materials like Aluminum alloys.

There's another benefit that hasn't been stated yet, but that's the consumption of lubricants. Even the most modern piston and gas turbine aviation engines consume quite a bit of oil in operation. These new magnetic gear boxes and friction-reducing aerospace coatings like RF-85 or non-caged bearings (Coo Space Bearings, Japan) make it possible to mostly eliminate the consumption of petroleum products.

louis · 2019-03-27 17:00:02

Just a thought...

We are used to aeroplanes towing advertising banners which are often 15x or more their body length (judging from google images). I guess there is nothing in principle to stop a plane towing a ultralightweight PV array. At 30K feet sunshine is pretty much guaranteed.

A large towed solar array might generate hundreds of KWs of power or even 1MW of power.

tahanson43206 · 2019-03-27 17:18:34

For Louis ... Bravo !!! That is an inspiring thought, and I will not be surprised if it comes to pass.

However, as a reminder, it was only a few months ago (ok, a couple of years), that the Solar Impulse made a flight around the world. I was one of the many observers who got to see the plane in flight, as it crossed the US.

The wings were covered in solar cells. The plane climbed to high altitude during the day while charging the batteries, and then descended while consuming stored energy at night. The batteries had to be replaced after the long flight to Hawaii.

If there is anyone in the forum readership who is not familiar with the flight, here is one of many links which tell part of the story:
https://www.theatlantic.com/photo/2016/ … ne/493085/

One observation I would make is that the Solar Impulse flew at a very restrained speed. The seaplanes that RobertDyck showed us are very likely to be flying at or very near the speeds to which they had become accustomed with hydrocarbon fuel as the energy storage medium.

A vehicle type for which your large array concept seems VERY appropriate is lighter-than-air vehicles, but I am skeptical of commercial success with that vehicle type. The double hulled vehicle that was relocated from the US to Britain looked promising, but I have heard little about it in recent months.

At the risk of introducing too much of a departure from RobertDyck's topic, I'd like to toss in a link about the "flying bum".
https://www.theverge.com/2019/1/13/1818 … 10-airship

The prototype vehicle was retired, and the company is working on a new, larger version.

Moving full circle ... there is no hint of solar power covering the fabric of the new vehicle, but if thin film solar cells can be light enough, perhaps they will find a place in this vehicle type.

(th)

louis wrote:

Just a thought...
We are used to aeroplanes towing advertising banners which are often 15x or more their body length (judging from google images). I guess there is nothing in principle to stop a plane towing a ultralightweight PV array. At 30K feet sunshine is pretty much guaranteed.
A large towed solar array might generate hundreds of KWs of power or even 1MW of power.

SpaceNut · 2019-03-27 17:50:45

Even if its double sided the amount of energy gathered is minimal when heading is straight towards or away from the sun (E-W) and will only get sun on one side or the other when going across its path (N-S).

Ammonia—a renewable fuel made from sun, air, and water—could power the globe without carbon

https://www.hydrogenics.com/technology- … uel-cells/

http://large.stanford.edu/courses/2013/ph240/white2/

Nitrogen‐Based Fuels: A Power‐to‐Fuel‐to‐Power Analysis

https://www.materialstoday.com/energy/n … -catalyst/

louis · 2019-03-27 19:38:24

I think you could only really work out how effective it was through trial and error. For one thing, clouds and the ground below reflect back a huge amount of insolation. I am sure with time the technology to tilt the array to the desired angle could be achieved, although - no doubt - more insolation will be collected on some routes than others and of course, no use for night flying.

SpaceNut wrote:

Even if its double sided the amount of energy gathered is minimal when heading is straight towards or away from the sun (E-W) and will only get sun on one side or the other when going across its path (N-S).
Ammonia—a renewable fuel made from sun, air, and water—could power the globe without carbon
https://www.hydrogenics.com/technology- … uel-cells/
http://large.stanford.edu/courses/2013/ph240/white2/
Nitrogen‐Based Fuels: A Power‐to‐Fuel‐to‐Power Analysis
https://www.materialstoday.com/energy/n … -catalyst/

kbd512 · 2019-03-27 19:53:07

Solar Impulse II
Wingspan: 236 ft
Solar panel Area: 2,901 ft^2
Power Available: 66kWe peak output from PV; 4 x 41kWh Lithium-ion battery pack (633kg); 4 x 13kW electric motors
Cruise Speed: 87mph day, 37mph night
Payload: 1 pilot
Cost Per Aircraft (Two Prototypes Built): $85M

Airbus A380
Wingspan: 261ft
Wing Area: 9,100 ft^2
Power Available: 300,000lbf of static thrust at sea level from 4 Rolls-Royce Trent turbofan engines and 85,472 gallons of Jet-A
Cruise Speed: 561mph, day or night
Payload (Typical): 575 passengers
Cost Per Aircraft (Typical): $446M

With a wing area equivalent to that of the A380's wing, perhaps we can build a solar-powered aircraft with the payload capacity of a four-seat Cessna 172 that flies at reduced speed, for the price of a brand new MD-80. Still, I think tube and fabric is fun to work with. I hope you have bottomless pockets, though, as this will be a little expensive. Anyone here have a couple hundred million burning a hole in their pocket? Who wants to do a build?

louis · 2019-03-28 08:09:12

Here's a different approach. People are working on passenger-carrying drones (PCDs). Some drones can move v. quickly now - over 170 MPH top speed.

Here's the first (?) model of a PCD:

https://www.theverge.com/2018/2/5/16974 … est-flight

If we built a series of solar power (or wind power) staging points, a drone could carry you all the way from London to New York, recharging at several points.

Yes, they would be quite slow compared with a jet ...but what if you could be picked up by a drone from near your home? Maybe you and your luggage get taken to the droneport by driverless car. Compared with getting to the airport, parking and all the rest, that might already save you an hour or two of travelling time. Your luggage might be put in a purpose-built "walk along" robot suitcase on wheels that attaches to the driverless car and is then released when you get to the droneport.

There would be no need for any elaborate check in procedure or the full range of anti-terrorist airport checks and searches because you could not hijack or kill anyone else. Passport control could be established with use of biometric data and passport checks within the drone just prior to departure. There would be no need for a long walk to your departure gate or a long wait for the call to board the plane, or a long wait while everyone gets their luggage in the racks and sits down. There would be no long wait while the plane taxis for take off. Put it altogether and you might well be saving anywhere between 6 and 10 hours of non flying time door to door on a transatlantic journey, so that is a huge time saving. In reality a current door to door journey from London to New York can easily take 15-18 hours.

So a country like the UK, which currently has maybe 10 significant international airports might in future have say 300 small "droneports" scattered all over the country each serving on average about 3000 people per day or 125 per hour. If the average drone carries say 3 people, then that would be just over 40 launches per hour or just under one a minute.

Once the staging posts are established, then the length of route is not an issue in terms of drone range. The net cost of the fuel will be extremely cheap. The current max range of a drone is (at two hours' flight) 75 kms. I would envisage that maybe at a future date your drone would have 10 brief charging stops on a transatlantic crossing using super-fast chargers. It might not be necessary for the drone to actually stop - it could slow down and pass over an induction rail fixed to a sea platform. Seaborne charging platforms (of the type used by Space X for landing) might be the way to go. You could have a network of these across the Atlantic. The network would shift and alter over time to avoid bad weather.

Toilet stops may be an issue!

Your luggage might travel separately on a drone in advance of you and you meet up again at the destination droneport.

I think if you could get the drone flight speed up to say 250 mph and provide that seamless door to door service this approach might work. The door-to-door travel time might be in the same range but you would have none of the aggravation of queuing, being searched, hauling luggage around, waiting for connections and so on.

Maintenance costs would be hugely reduced I would think, compared with jet aircraft.

kbd512 · 2019-03-28 13:00:44

Louis,

I admire your tenacity with this battery and solar panels or wind turbines only idea, but at some point fundamental practicality should enter into your thought process. Batteries can work for some types of flying, but intercontinental flights aren't one of them at the present time. Frankly, I'm not sure why that matters. Most aircraft, by sheer weight of numbers, don't fly intercontinental routes. The best use of batteries would be for corporate aircraft and owner-operator light sport aircraft. That is the bulk of the fleet, by a good wide margin. Usage pattern counts for a lot. All trainers and commercial airline services require much higher utilization rates to remain profitable. If someone invents a battery that fully recharges in 30 minutes, then trainers and small passenger carrying aircraft would become practical.

It doesn't take 18 hours or anything close to it to go to Heathrow from JFK. It's a 7.5 hour flight. If you're spending 10 hours at the airport or going to and from the airport, then you, the traveler, or your government are spending a lot of time goofing off. Demonstrably false assertions aside, international travel typically adds 3 to 4 hours to the total travel time, all of which is based upon security screening and exceptionally poor travel habits of our average passenger when it comes to baggage handling. The more unnecessary crap you take with you, the longer it takes to travel. If everyone used soft-sided luggage designed to fit in overheads, that they could actually carry, and airlines and passengers spent less time messing around with luggage and seating assignments, that would save a minimum of 1 hour.

The amount of time saved by picking someone up at their home is insignificant compared to the time it takes to cross the Atlantic at 170mph. It would take 20 hours and 30 minutes of total flight time at 170mph, non-stop. The jets that we currently use take people across the pond in about 7 hours and 30 minutes. An electric aircraft is closing in on triple the flight time. Once ascent, descent, landing, and traffic pattern delays are taken into account, that will flat out dictate at least triple the current flight time. Current batteries are insufficient for Atlantic crossings using anything resembling practical passenger carrying aircraft.

Bye Aerospace (Englewood, CO) has created two products (actual products, not notional products) that use batteries, the Sun Flyer 2 and Sunflyer 4. The 2-model seats 2 people. The 4-model seats 4 people. The 4-model can move at 150mph. Both use the latest and greatest batteries, composite construction materials, and avionics. Both are price competitive with trainers or light sport aircraft like the Cessna 152's (2-seat) and Cessna 172's (4-seat). Performance is in line with similar gas-powered airframes.

The Sun Flyer 2 is directly comparable to a gasoline-powered (Jabiru 3300) Arion Lightning LS-1 (a light sport aircraft), which the Sun Flyer 2 is based off of (the 2-model's airframe is a direct copy of the Arion airframe). Both fly at roughly the same cruise speed, which would be about 135mph, and can stay in the air for roughly the same amount of time. IIRC, the owner of the company said that Sun Flyer 2's best cruise speed is 120mph. Sun Flyer 2 is supposed to be FAR 23 certified by 2020.

If you happen to have a 1kWh/kg battery technology on hand that fully recharges in 45 minutes, then someone can build a corporate aircraft that flies at turboprop speeds with approximately half the range of a turboprop powered aircraft. If we had CNT fabric technology commercially available at prices competitive with carbon fiber, then the weight problem becomes a lot easier to solve. Currently, we have neither.

Eviation - Alice

Alice
MTOW: 14,000lbs
Battery Weight: 9,100lbs (with 400Wh/kg batteries)
Airframe and Payload Weight: 4,900lbs
Range: 650 miles (with 400Wh/kg batteries)
Cruise Speed: 276mph (240kt)
Seats: 9

*** Begin Edit ***
Note: Information on Alice comes directly from Eviation's CEO, Omer Bar-Yohay

Source: Eviation Aircraft Plans 9-Seat Electric Airplane - Coming Soon? #CleanTechnica Interview

Omer also claimed 300mph (260kt) during the interview, but their website now says 240kt

Alice Battery Capacity: 900kWh battery at 400Wh/kg (extra weight is for battery cell packaging and power transfer cables)

LNH3 Energy Equivalent: 84lbs of H2 or 82.35 gallons of LNH3 or 468.8lbs of LNH3

269.1 gallons / 1,531.2lbs of LNH3 for FCEV Alice variant to range match the Pilatus PC-12NG with its 397.6 gallons / 2,704lbs of Jet A

In aviation, weight counts for a lot. Alice would weigh 7,003lbs with 3kW/kg (current production), which is half the weight of the battery powered Alice and 70% the weight of a Jet A / turboprop powered Alice.

Who wants to lug around 4 tons of laptop batteries for less than 1/3 the range of the PC-12?

Who is actually serious about wanting practical and affordable electric aircraft?
*** End Edit ***

Pilatus PC-12NG
MTOW: 10,450lbs
Weight: 6,373 (1 pilot, 9 pax, no fuel)
Range: 2,123 miles (with VFR reserve fuel)
Cruise Speed: 328mph
Seats: 9

The turboprop that has more than triple the range because it's 3,550lbs lighter with full fuel and 9 pax. It only gets lighter as it consumes fuel during the flight. The batteries inside Alice weigh more than no-fuel weight of the PC-12NG with 10 people on board and you have to carry them for the entire flight. The batteries weigh 3.37 times as much as the maximum fuel load of the PC-12NG. Merely to achieve MTOW parity with the turboprop, the batteries must store at least 1,346Wh/kg. Is the design issue sufficiently clear, yet?

The electric aircraft's range / speed and battery power increase linearly. As more battery is required to fly greater distances or to fly faster, the battery weight proportionally increases in a very predictable manner. Alice is already more rifle bullet with wings than prototypical propeller-driven aircraft. You'll need to overturn some basic physical laws or obtain batteries with energy densities exceeding 1kW/kg. Even then, you still won't come close to matching that turboprop on range since you're carrying the battery weight for the entire flight. Use tools that are appropriate for the job to be done, with current rather than fictional technology, and the problems are solvable.

In order to support the passenger drone idea, a massive upgrade of the air traffic control system would be required to prevent mid-air's. As UAV's of various flavors have exploded in numbers, the US has struggled to come up with solutions to deconflict traffic. This is an entirely solvable problem with modern miniaturized avionics and sensor technology, but it won't be cheap.

I have a much easier time believing that modern Alkaline (very cheap catalysts, 70% to 75% efficient, 100C - 200C op. temp) or PEM (very expensive catalysts, 60% - 70% efficient, 70C op. temp) fuel cells (3kW/kg gravimetric and 3.5kW/l volumetric, as high as 5kW/kg and 5kW/l in lab prototypes) and dense liquid fuels that store H2 easily at relatively low pressures, like LNH3 (114psi and 5.08lbs/gallon at room temperature) are practical power plants that can match gas turbines on power to weight and surpass them in terms of reliability and simplicity. At room temperature, LNH3 has roughly the same H2 fraction, by volume, as Jet A, and slightly more at -28F. Using an efficient plasma cracker, which Toyota has perfected and uses in refueling stations for the Mirai FCEV to deliver exceptionally pure H2, we get more "bang" for our buck. LNH3 is also considerably cheaper than Jet A and uses plentiful CH4. Use the new EUV lasers to extract high purity C from CO2 created by the Haber-Bosch process to produce the LNH3, as we need C uncontaminated with metals for making CNT and Graphene. LNH3 is even more difficult to ignite than Jet A to boot and will rapidly disperse into the atmosphere if there is a fuel leak. Stratospheric temperatures are ideal for maintaining LNH3 at 1 atmosphere. The pressurized wing tanks can also be used to resist the aerodynamic loads created by flying at moderate to high subsonic speeds.

We start with a fuel that's 75% the weight of Jet A, containing nearly identical H2 content by volume (LNH3 at -28F -> 5.69 * 0.17755 = 1.01lbs H2/gallon or 0.9lbs H2/gallon at 70F; Jet A at 70F -> 6.8 * 0.15 = 1.02lbs H2/gallon), crack it with a plasma cracker, and feed it to fuel cells that are at least twice as efficient as gas turbine engines for a given level of output. From there, we deliver the power to electric motors and propellers to produce thrust. At 5kW/kg, we've already matched the gas turbine's PWR using 15kW/kg electric motors on any flight, irrespective of duration. If the flight requires more than 1 hour of fuel, then we have a progressively lighter aircraft that flies further and faster as a consequence of its fueled weight. As flight duration increases, the advantage becomes more pronounced. In practice, burning Jet A means paying for 1.8 times as much fuel that costs 4 times as much. That's 7.2 times the cost for fuel that does the same work, either way. Nobody needs to convince a pilot, never mind a bean counter at an airline service, which is better. However, that was for retail LNH3 prices. Wholesale prices are 50% of retail, on average. Now we're up to 14.4 times as much. Nobody in their right mind would pay for that. Fuel is the greatest operational expense.

At 15kW/kg, our electric motor technology is already good to go and then some. No gas turbine engine on the planet can match modern aircraft electric motors for efficiency and PWR. Heck, EV motors are rapidly approaching the GE90's PWR. Future technological development in CNT conductors and Iron Nitride permanent magnets will ensure that only rocket engines can best them in the PWR department. 25kW/kg is easily achievable with CNT conductors and Fe4N magnets. Superconducting electric motors have the potential to provide a half order of magnitude PWR improvement over gas turbines, at appropriate scale, so 50kW/kg compared to the GE90's 10kW/kg.

Last edited by kbd512 (2019-03-28 13:54:49)

kbd512 · 2019-03-28 17:25:53

Further Notes:

My wording regarding the H2 content was wrong. I should've stated that LNH3 at -33F has about the same H2 content as Jet A at 70F, rather than the same content as LNH3 at 70F. Anyway, my math is still correct.

Some N2 from the plasma cracker should be run through heat exchangers attached to the electric motors to remove heat from the motors and provide hot bleed air to the leading edges of the air intakes, wings, empennage, and cockpit windscreen to prevent icing.

CNT wiring / fabrics / composites are poised to revolutionize airframes and wiring:

Nanocomp Technologies - Miralon Yarn

The CNT products come as wires, wire shielding, woven fabrics, papers or tapes, yarns, threads, and pastes or pulp- used for joining surfaces, like wet or dry micro (glass beads, but CNT or fullerenes rather than glass).

If Alice's airframe weighs 2,500lbs when constructed of carbon fiber composites, then it weighs 1,250lbs if made from CNT and would be 10 times stronger than carbon fiber composite at that weight. Pound for pound, CNT composite (with material defects that have now been corrected) is 20 times stronger than carbon fiber composite. Using the new process to produce defect-free CNT, the strength to weight is mind blowing. That means we can build airframes that are truly durable and low-maintenance.

If someone puts this all together and retains the 780kW power plant, then they'll end up with a FCEV version of Alice that weighs about 1/3rd of what the BEV version of Alice weighs, cruises faster than the PC-12NG's Vne, accelerates and climbs like a light jet, needs even less fuel for equivalent range, and is a truly durable airframe capable of withstanding serious punishment at the hands of a ham-fisted pilot.

Oh, yes, better magnets:

Niron Magnetics

louis · 2019-03-28 19:48:00

kbd512 wrote:

It doesn't take 18 hours or anything close to it to go to Heathrow from JFK. It's a 7.5 hour flight. If you're spending 10 hours at the airport or going to and from the airport, then you, the traveler, or your government are spending a lot of time goofing off. Demonstrably false assertions aside, international travel typically adds 3 to 4 hours to the total travel time, all of which is based upon security screening and exceptionally poor travel habits of our average passenger when it comes to baggage handling.

I googled on the flight time and it is given as 8 hours (might be faster flying west to east). You are advised to arrive at the airport at least 2 hours in advance of your flight departure. Also flights of big aeroplanes are often delayed for various reasons. You could probably add on 15 minutes for those delays. London Heathrow has a large catchment area. People often travel 3-4 hours to get to the airport and they often add on 30 mins or an hour to their journey time because of possible traffic congestion. So far I've got 8 plus 3 plus 2.5 plus .25 = 13.75. I can't imagine things are better at your end. You have to taxi to the terminal, wait to be allowed off, collect your baggage and get through passport control and customs. You aren't getting out of that airport in anything under an hour . You then have to travel to your home destination...There are probably more international airports in the USA but I imagine most people's journey time is going to be around 2 hours on average to get to the door (waiting for buses, trains, taxi drivers, collecting hire cars etc). I make that 16.75. hours total - as a rough average. I think I quoted 15-18 hours originally. Even if 60% of people's journey time is quicker than 16.75 hours, that's still 40% of the total market who might be attracted to a drone crossing.

The amount of time saved by picking someone up at their home is insignificant compared to the time it takes to cross the Atlantic at 170mph. It would take 20 hours and 30 minutes of total flight time at 170mph, non-stop. The jets that we currently use take people across the pond in about 7 hours and 30 minutes. An electric aircraft is closing in on triple the flight time. Once ascent, descent, landing, and traffic pattern delays are taken into account, that will flat out dictate at least triple the current flight time. Current batteries are insufficient for Atlantic crossings using anything resembling practical passenger carrying aircraft.

I never claimed this was all technically feasible at this point. I was simply referring to you to what drones can already do - a mere 10 years after they really came on the scene.

I am proposing staging points, so your point about battery life is pretty much redundant. I am also arguing that we probably already have the technology for a drone to fly over an induction rail and charge its batteries without stopping its flight.

Bye Aerospace (Englewood, CO) has created two products (actual products, not notional products) that use batteries, the Sun Flyer 2 and Sunflyer 4. The 2-model seats 2 people. The 4-model seats 4 people. The 4-model can move at 150mph. Both use the latest and greatest batteries, composite construction materials, and avionics. Both are price competitive with trainers or light sport aircraft like the Cessna 152's (2-seat) and Cessna 172's (4-seat). Performance is in line with similar gas-powered airframes.

My proposal relates to drones not aeroplanes.

If you happen to have a 1kWh/kg battery technology on hand that fully recharges in 45 minutes...

EVs are already being recharged within 5 mins it is claimed:

https://insideevs.com/gbatteries-claims … -charging/

We are certainly down to a few minutes for quite large batteries.

The electric aircraft's range / speed and battery power increase linearly. As more battery is required to fly greater distances or to fly faster, the battery weight proportionally increases in a very predictable manner.

Something similar no doubt applies to drones. However, once again I have to state the obvious: staging points for recharging basically makes this a redundant discussion. The discussion should be how feasible/costly is it to provide staging posts for drones on intercontinental flights. Clearly drone passenger transport will likely become established for domestic flights first, where you can combine staging posts with launch points. Intercontinental drone transport is a much bigger ask - but I think for the reasons set out above (rough parity in door-to-door journey time but huge increase in quality of journey experience (avoiding humiliating searches, crowds, queuing, not having to drag luggage around and so on) it would prove popular.

In order to support the passenger drone idea, a massive upgrade of the air traffic control system would be required to prevent mid-air's. As UAV's of various flavors have exploded in numbers, the US has struggled to come up with solutions to deconflict traffic. This is an entirely solvable problem with modern miniaturized avionics and sensor technology, but it won't be cheap.

Drones are going to have virtually no interaction with big planes. They can easily be provided with compatible collision-avoidance systems (just like the beepers on your car when you park). There might be some raised risk of collision with helicopters which tend to fly all over the place. That will need some thought, of course. We agree it's a problem that can be solved. Personally I think it will be v. cheap. We currently spend a hell of a lot on air traffic control, including a huge human element because it involves v large craft being funnelled into the same v. restricted landing space. That's really a crazy way of doing things. Drone transport and drone control will be much more diffused and devolved. There are bound to be accidents at some point, but they will kill maybe 10 people max, not 300. There will never be a drone hijack. You won't be able to hijack. It's flight path can never be under the control of someone on board.

I will have to re-read the rest of your post to get any kind of hold on the tech stuff you reference!

Last edited by louis (2019-03-28 19:50:35)

kbd512 · 2019-03-28 22:36:39

Louis,

Travel Times
Your arguments about local travel times are indicative of what better mass ground transportation would solve without resorting to having hundreds of aircraft taking off from hundreds of airfields without ATC or automated ATC. In any event, that's an artificial limitation of ground transportation infrastructure, not aviation. If you think you're not going through customs just because you boarded an aircraft without other people onboard, then you really should become familiar with the laws. Whenever you cross the border between the US and Canada in a private aircraft, for example, you have to land for inspection. You and the aircraft will be inspected by USCIS. There is no way around that requirement and there never has been.

Battery Charge Times
How much damage was done to those EV battery packs by charging in 5 minutes?

If you don't care about how many cycles the battery pack is capable of or capacity loss, then we can charge them even faster than that as long as we keep them cool enough. GBatteries' website says half charge in 5 minutes, full charge in 10 minutes, but not one word about how that affects battery life. That's still a lot better than most others out there, so I intend to read about how they did that. If they can do that without damaging the battery, then primary trainer and very short haul aircraft could also use batteries in a practical manner.

As I previously stated, I think batteries are the most practical power source for owner-operators who fly once a week or less, typically 2 hours or less, and with nobody else onboard (stats show that most of the time owner-operators of 2-seaters are the only ones aboard, which begs the question, "Why not just build and fly your own high performance single seat aircraft, since that's how most of us actually use it?").

If I never have to utter the words "fuel to the tabs" again, I'm down with that every day of the week and twice on Saturday (when I normally fly). If you don't regularly fly (run the engine at significant power for at least an hour or so, at least once per week), aviation engines have a very nasty habit of corroding. As with everything else related to this hobby, that also gets expensive pretty quick.

Would I fly a battery-powered electric aircraft?

Absolutely. Power is power. If I don't have to use a headset in the cockpit in Texas heat, even better.

Can this replace a turboprop, or our trusty Lycoming four-bangers, at the present time?

Unfortunately, no. The energy density just isn't there. We need more power, Scotty.

I don't know any pilots who like paying for fuel. Right now, that's just part of the game. If batteries drastically improve or someone just makes the quantum logical leap that LNH3 stores about 1.5 times as much H2 as LH2, by volume, and that modern automotive fuel cells can deliver the power required, then we may very well see electrification of aviation in a relatively short period of time. Aside from that possibility, it'll be another couple of decades before the order of magnitude energy density improvement of batteries materializes.

As mass manufacturing lowers the cost of CNT composites and wiring for aircraft, that will surely help to reduce the weight of aircraft through stronger and lighter airframe structures. The Aluminum and Magnesium CMC's are prime candidates for stronger and lighter landing gear. Beyond that, more powerful and lighter electric motors and fuel cells seem to be the most practical liquid hydrocarbon alternatives presently available. Nobody who flew behind an electric motor ever had a cross word to say about the motor, apart from the fact that it guzzles juice from the batteries. Flying requires lots of continuous power, unlike most city driving. I think everyone already understands that there aren't any simpler or more reliable or smoother operating power plants to be had.

Drones vs Airplanes
In point of fact, anything that flies is an aircraft. You can choose to categorize that aircraft however is most pleasing to you, but that doesn't change how it's regulated. A "drone" carrying a human onboard is an "airplane" or "aeroplane" or "rotary wing aircraft" without a pilot. Whatever you choose to call it, if it's used to provide commercial air transportation services, then it's subjected to heavy regulation.

I already told you what current electric aircraft with batteries are capable of. They can compete with what the FAA calls "Light Sport Aircraft" or LSA's. All LSA's are limited to 2 people onboard, though there is talk of changing regulations so that LSA's that can carry entire families. LSA's are limited in various other ways as well, to include a maximum level flight speed of 138mph in that category. The SunFlyer 2 can cruise at 120mph. It can technically go faster than that by trading battery capacity for range, but not much faster because it's battery capacity limited and weight limited by the basic design of the Arion LS-1, which was designed as a LSA.

Security
Those "humiliating searches" that you mentioned serve two purposes. The first is Kabuki Theater to give people like you who are afraid of things for irrational reasons the categorically false notion of "safety" or "security". Nothing and no one on Earth can actually prevent anyone else from killing you if that person doesn't care about the consequences of committing that crime. Some people have wildly irrational fears of things that are less likely to kill them than getting struck by lightning, but the fear is still quite real. Your fear of nuclear power comes to mind, for example. I may not understand it, but I still have to acknowledge that the fear is real. That is the psychological rationalization behind the facade of "protection" that can never actually be provided.

The second is that most criminals are so absurdly stupid that we can employ a lot of people who don't have to be much smarter in order to apprehend them. If you think you're somehow getting out of security procedures because you boarded a private aircraft or corporate aircraft that crossed an international boundary, then you should really see how that works here, post-9/11.

The idea that a terrorist couldn't hijack a drone that has to be connected to multiple networks is laughably absurd. Anyone who has direct physical access to a robotic machine can make it do whatever they want it to do, period. A good hacker can do it without any physical access. Anyway, passenger aircraft now have reinforced cockpit doors. Since the US implemented that simple little measure, so long as the doors were locked by the pilots, there have been no further cockpit intrusions. The passengers have also learned that they outnumber the hijackers and can ruthlessly subdue anyone who tries anything criminal using overwhelming numerical superiority. Recently, a nutter at Sea-Tac who was part of a maintenance crew hijacked a twin turboprop, went for a joyride for several minutes, and buried it in a small island off the coast. He'd never flown an aircraft in his life, let alone a twin turboprop. Magical thinking aside, not amount of hand-waving on your part will ever change that simple fact.

Traffic Deconfliction
Drones already interfere with passenger carrying aircraft. Putting more of them in the air won't make flying any less hazardous. However, we do already have certain systems to avoid mid-air's. We call it "ADS-B". It's already saved quite a few lives and drones from mid-air collisions. It's a little funny that the point was dismissed, though, given how concerned you appear to be regarding terrorism. Anyway, I'm not arguing for or against drones. I'm simply pointing out what's so obvious to someone who flies little airplanes.

The General Discussion
Actually, I think the discussion should be about how we can make electric aircraft affordable and practical using existing technology, rather than waiting for battery technology that doesn't exist or other non-existent and/or grossly impractical technologies such as this "induction rail" system that will somehow transmit tens of kilowatts to megawatts of power to single seat aircraft flying across the Atlantic.

In the future we'll have this "teleportation" system that allows us to instantly arrive at whatever destination in the galaxy we want to go to. We won't need cars, buses, trains, planes, or even spacecraft. That would be a dream come true, but right now we're still burning coal and some people are burning their own poop just to cook dinner. Baby steps, Louis.

In light of that fact, I humbly suggest that you take a look around at the technology that does exist in the "here and now" and compare it with how much advancement would be required in order for your preferred visionary future technology to take over, with respect to where the technology presently is. After that, ask yourself how long you want to wait for the future to happen.

Our very best battery powered aircraft can't match the range and speed of a little IO-360 powered LSA. However, using presently available fuel cell and electric motor technology that's already found in numerous passenger vehicles and fuel already used in massive quantities as a fertilizer by the agricultural industry, we can build and operate aircraft that have every bit of the range and speed of PT6A (turboprop) powered commuter aircraft, and then some, that also cost considerably less to operate as a function of fuel costs.

RobertDyck · 2019-03-29 04:20:20

Perhaps utility of aircraft depends where you live. Here a "short hop" is a Cessna Caravan or Cessna Grand Caravan from St Andrews airport outside Winnipeg to Pauingassi and back. Pauingassi doesn't have an airport, just a lake with a dock for fishing boats, so it requires a float plane. St Andrews doesn't have water, so the plane must also have wheels. And Pauingassi doesn't have aircraft fuel, so the aircraft has to make both flights on a single tank of fuel. That flight is 280km each way. Could a battery powered aircraft do that?

And the aircraft is used to transport supplies for the Northern Store, which is the only store for the community. It carries groceries, convenience store food, fishing rods and tackle, TVs and satellite receivers, furniture and household appliances, clothing, tools. The first time I went to Pauingassi, they had several flights in one day to deliver all the cargo the Northern Store required, so that means full load that a Cessna Grand Caravan can carry. When I returned the aircraft had all passenger seats removed, I sat in the co-pilot seat. Could an electric aircraft do that?

::Edit:: Here jet fuel is Jet A-1. Jet A is only available in the US and a couple airports in Canada: Toronto, Vancouver, not sure where else. Russia and former members of the Soviet Union use a Russian standard fuel, all other nations of the world use Jet A-1. The issue is Jet A freezes at -40°C (-40°F), while Jet A-1 freezes at -47°C (-53°F). Outdoor temperature can get to -40°C, although not often. One day last January it got that cold here in Winnipeg. That was the overnight low, the coldest night of the year, and last time it got that cold was one night in January 2005, but it does happen. Farther north it happens more often, and temperature at altitude is colder. There's also Jet B for extreme north, but here we use Jet A-1. Jet A has specific energy of 11.95 kWh/kg while Jet A-1 is 11.90 kWh/kg. Not a big difference, but it does mean a slightly heavier fuel load.

Last edited by RobertDyck (2019-03-29 08:51:59)

louis · 2019-03-29 08:01:58

kbd512 wrote:

Louis,
Travel Times
Your arguments about local travel times are indicative of what better mass ground transportation would solve without resorting to having hundreds of aircraft taking off from hundreds of airfields without ATC or automated ATC. In any event, that's an artificial limitation of ground transportation infrastructure, not aviation. If you think you're not going through customs just because you boarded an aircraft without other people onboard, then you really should become familiar with the laws. Whenever you cross the border between the US and Canada in a private aircraft, for example, you have to land for inspection. You and the aircraft will be inspected by USCIS. There is no way around that requirement and there never has been.

I can only speak of the UK situation. Travelling to London's airports is a nightmare of queuing and congestion. Even if you spent 10% of your GDP on providing mass ground transportation links, you are never going to get to every door in seamless fashion. Incidentally airport parking can add another 20 minutes both ends. With robot mobile luggage holders, self drive taxi cars and hundreds of droneports, these problems are solved.

Tens of billions are being spent on new underground lines but it won't resolve the issues as our population is growing at 4 to 5 million a decade. Tens of millions of people have to travel in 100-200 miles or more to get to Heathrow.

I accept customs will still be a requirement. But my experience of customs is that that is never a cause of queues. It's passport control and anti-terrorism searches that cause queues. Drones could be fitted with automated monitoring equipment assessing the behaviour of passengers. The lead passenger might be asked to confirm that there is no contraband on board. Any suspicious behaviour verbal or facial could prompt an alert for a customs search at the other end.

Battery Charge Times
How much damage was done to those EV battery packs by charging in 5 minutes?
If you don't care about how many cycles the battery pack is capable of or capacity loss, then we can charge them even faster than that as long as we keep them cool enough. GBatteries' website says half charge in 5 minutes, full charge in 10 minutes, but not one word about how that affects battery life. That's still a lot better than most others out there, so I intend to read about how they did that. If they can do that without damaging the battery, then primary trainer and very short haul aircraft could also use batteries in a practical manner.
As I previously stated, I think batteries are the most practical power source for owner-operators who fly once a week or less, typically 2 hours or less, and with nobody else onboard (stats show that most of the time owner-operators of 2-seaters are the only ones aboard, which begs the question, "Why not just build and fly your own high performance single seat aircraft, since that's how most of us actually use it?").
If I never have to utter the words "fuel to the tabs" again, I'm down with that every day of the week and twice on Saturday (when I normally fly). If you don't regularly fly (run the engine at significant power for at least an hour or so, at least once per week), aviation engines have a very nasty habit of corroding. As with everything else related to this hobby, that also gets expensive pretty quick.
Would I fly a battery-powered electric aircraft?
Absolutely. Power is power. If I don't have to use a headset in the cockpit in Texas heat, even better.
Can this replace a turboprop, or our trusty Lycoming four-bangers, at the present time?
Unfortunately, no. The energy density just isn't there. We need more power, Scotty.
I don't know any pilots who like paying for fuel. Right now, that's just part of the game. If batteries drastically improve or someone just makes the quantum logical leap that LNH3 stores about 1.5 times as much H2 as LH2, by volume, and that modern automotive fuel cells can deliver the power required, then we may very well see electrification of aviation in a relatively short period of time. Aside from that possibility, it'll be another couple of decades before the order of magnitude energy density improvement of batteries materializes.
As mass manufacturing lowers the cost of CNT composites and wiring for aircraft, that will surely help to reduce the weight of aircraft through stronger and lighter airframe structures. The Aluminum and Magnesium CMC's are prime candidates for stronger and lighter landing gear. Beyond that, more powerful and lighter electric motors and fuel cells seem to be the most practical liquid hydrocarbon alternatives presently available. Nobody who flew behind an electric motor ever had a cross word to say about the motor, apart from the fact that it guzzles juice from the batteries. Flying requires lots of continuous power, unlike most city driving. I think everyone already understands that there aren't any simpler or more reliable or smoother operating power plants to be had.

I don't say we are at that stage yet...this was looking into the future. Clearly the way drone transport will develop is single city transport first, then inter-city transport, then national scale transport...then we will see some international travel. UK - mainland Europe, US to Canada.

Drones vs Airplanes
In point of fact, anything that flies is an aircraft. You can choose to categorize that aircraft however is most pleasing to you, but that doesn't change how it's regulated. A "drone" carrying a human onboard is an "airplane" or "aeroplane" or "rotary wing aircraft" without a pilot. Whatever you choose to call it, if it's used to provide commercial air transportation services, then it's subjected to heavy regulation.
I already told you what current electric aircraft with batteries are capable of. They can compete with what the FAA calls "Light Sport Aircraft" or LSA's. All LSA's are limited to 2 people onboard, though there is talk of changing regulations so that LSA's that can carry entire families. LSA's are limited in various other ways as well, to include a maximum level flight speed of 138mph in that category. The SunFlyer 2 can cruise at 120mph. It can technically go faster than that by trading battery capacity for range, but not much faster because it's battery capacity limited and weight limited by the basic design of the Arion LS-1, which was designed as a LSA.

Short term I can't see aircraft competing with drones on safety. There is just way too much that can go wrong in a plane.

Security
Those "humiliating searches" that you mentioned serve two purposes. The first is Kabuki Theater to give people like you who are afraid of things for irrational reasons the categorically false notion of "safety" or "security". Nothing and no one on Earth can actually prevent anyone else from killing you if that person doesn't care about the consequences of committing that crime. Some people have wildly irrational fears of things that are less likely to kill them than getting struck by lightning, but the fear is still quite real. Your fear of nuclear power comes to mind, for example. I may not understand it, but I still have to acknowledge that the fear is real. That is the psychological rationalization behind the facade of "protection" that can never actually be provided.
The second is that most criminals are so absurdly stupid that we can employ a lot of people who don't have to be much smarter in order to apprehend them. If you think you're somehow getting out of security procedures because you boarded a private aircraft or corporate aircraft that crossed an international boundary, then you should really see how that works here, post-9/11.

Security checks on people flying their own planes in the USA are way less severe - effectively non existent, since you can basically have a plane on your ranch and just get in it and fly off with nothing to stop you taking a (probably not v. damaging) pop at a local tower. Drones are entirely different because their flight path is not controlled by the occupants but by onboard computers working with central servers.

The idea that a terrorist couldn't hijack a drone that has to be connected to multiple networks is laughably absurd. Anyone who has direct physical access to a robotic machine can make it do whatever they want it to do, period. A good hacker can do it without any physical access. Anyway, passenger aircraft now have reinforced cockpit doors. Since the US implemented that simple little measure, so long as the doors were locked by the pilots, there have been no further cockpit intrusions. The passengers have also learned that they outnumber the hijackers and can ruthlessly subdue anyone who tries anything criminal using overwhelming numerical superiority. Recently, a nutter at Sea-Tac who was part of a maintenance crew hijacked a twin turboprop, went for a joyride for several minutes, and buried it in a small island off the coast. He'd never flown an aircraft in his life, let alone a twin turboprop. Magical thinking aside, not amount of hand-waving on your part will ever change that simple fact.

This is fantasy stuff. There will be all sorts of failsafe measures used to prevent hacking. Even if a hacker gets control of a drone what are they going to do? One tiny drone is not going to going to cause a major death toll. You could in any case have an emergency override on board for "Immediate Safe Emergency Landing" (ISEL) which a central control unit could alert passengers to make use of if there was any sign of divergence from authorised flight path. You could also have a separate monitoring device which would activate an ISEL if it detects a departure from the original flightpath. No bank has ever been robbed of all its money by a hacker. There will be similar levels of security I am sure to prevent some evil hacker sending hundreds of drone passengers to their death. You just need lots of autonomous failsafe systems, as well as all the normal anti-hacker defences.

Traffic Deconfliction
Drones already interfere with passenger carrying aircraft. Putting more of them in the air won't make flying any less hazardous. However, we do already have certain systems to avoid mid-air's. We call it "ADS-B". It's already saved quite a few lives and drones from mid-air collisions. It's a little funny that the point was dismissed, though, given how concerned you appear to be regarding terrorism. Anyway, I'm not arguing for or against drones. I'm simply pointing out what's so obvious to someone who flies little airplanes.

Presumably it's easier for a drone to take evasive action that a plane travelling at 300 MPH . The drones will be automated.

The General Discussion
Actually, I think the discussion should be about how we can make electric aircraft affordable and practical using existing technology, rather than waiting for battery technology that doesn't exist or other non-existent and/or grossly impractical technologies such as this "induction rail" system that will somehow transmit tens of kilowatts to megawatts of power to single seat aircraft flying across the Atlantic.

The induction rail idea was purely for drones because drones can vary speed in a microsecond and can hover. We already have induction charging on electric roads, so in principle this is not an issue. It would avoid the need to "park up" the drones on a platform.

There is a problem with staging points for drones because of the depth of most of the Atlantic. Looking at the sea charts we need to develop either floating sea platforms , mega tall platforms (over 4000 feet in length) or perhaps develop some sort of stabilised floating platform similar to floating wind turbines which are anchored to 100 ton weights on the sea floor.

https://www.youtube.com/watch?v=PUlfvXaISvc

In the future we'll have this "teleportation" system that allows us to instantly arrive at whatever destination in the galaxy we want to go to. We won't need cars, buses, trains, planes, or even spacecraft. That would be a dream come true, but right now we're still burning coal and some people are burning their own poop just to cook dinner. Baby steps, Louis.
In light of that fact, I humbly suggest that you take a look around at the technology that does exist in the "here and now" and compare it with how much advancement would be required in order for your preferred visionary future technology to take over, with respect to where the technology presently is. After that, ask yourself how long you want to wait for the future to happen.

I think the first passenger drone contract is due to go into operation in Dubai in the next couple of years - this isn't a dream technology.

Our very best battery powered aircraft can't match the range and speed of a little IO-360 powered LSA. However, using presently available fuel cell and electric motor technology that's already found in numerous passenger vehicles and fuel already used in massive quantities as a fertilizer by the agricultural industry, we can build and operate aircraft that have every bit of the range and speed of PT6A (turboprop) powered commuter aircraft, and then some, that also cost considerably less to operate as a function of fuel costs.

All well and good but planes are not going to provide that civilised door to door experience for the masses, I feel.

kbd512 · 2019-03-29 14:23:43

Robert,

In the case of the Cessna Caravan, the answer is "almost" if we have a complete battery pack energy density of 300Wh/kg. I believe we can manage that. At 400Wh/kg for a complete battery pack, yes. The 208 model has a max fuel load of 1,009kg. That translates to a 303kWh battery pack at 300Wh/kg or 404kWh at 400Wh/kg. There is absolutely no way to also carry 9 pax, at 200lbs/pax, with that 1,009kg battery. Your useful load is reduced to a maximum of 5 pax. The Part 23 waiver allows some Caravans to carry 13 pax, but again, completely out of the question with the battery. I don't see much of a market for a 208 with less than 1/3rd the range and 1/2 payload capacity (it's like having max fuel onboard at all times), but I could always be wrong about that. Using fuel cells, a 208 could carry 9 pax, full fuel, and still be well under its gross weight rating.

You'd have little to no reserve power left for diverts, if you had to fly there and back on a single charge. If you could recharge for 10 minutes at the destination using that new super charger technology from GBatteries that Louis previously mentioned, then this could work for that particular use case.

Compare the useful load of the 208 Caravan (all Aluminum) and the CompAir 8 (all composite with a carbon fiber fuselage). Notice that the 208's empty mass fraction is 59% of gross. The 8's empty mass fraction is 50% of gross. That's where new materials come into play. With a 30% empty mass fraction, which is what CNT composites would enable, you have a lot more weight to allocate to batteries or fuel cells and still retain sufficient useful load for passengers or cargo. Typically, composite airframes are not nearly as fatigue life limited as Aluminum.

If they decide to build out the required recharging infrastructure, this would be a lot easier to do. I still don't understand what the issue is with using appropriate technology. Modern fuel cells can provide plenty of power for a modest weight increase. For commercial aviation applications, there are only niche use cases for batteries until the energy density and cell life drastically improves.

The 5kW/kg fuel cell that Intelligent Energy is working on is just a refinement of their existing fuel cell to minimize the mass and complexity of the balance of plant. The CompAir 8 uses a Walter 601D that weighs 197kg and provides 490kW. That translates into a 100kg fuel cell, at 5kW/kg. The electric motors and magnetic gearbox would weigh around 50kg or so. That leaves plenty of mass for cooling and batteries and plumbing. The wings could be dry and use a pair of 68 gallon LNH3 tip tanks to improve airflow characteristics around the tips, just like the winglets do. The fuel load would be 774lbs (LNH3) vs 1,224lbs (Jet A). The entire airframe with full fuel and 8 people becomes lighter by about 550lbs.

LNH3 FCEV CompAir 8
Empty Weight: 2,700lbs (50kg Magnax axial flux motor and magnetic gearbox; 100kg Intelligent Energy 5kW/kg PEM fuel cell)
Full Fuel Weight: 3,474lbs (using 2 wingtip mounted 68 gallon LNH3 tanks)
Weight of 1 pilot and 7 pax (200lbs each): 1,600lbs
Gross Weight: 5,074lbs

COMP AIR 8 Turbine

Walter M601D Turboprop "Firewall Forward" Engine Package for Comp Air Turboprops

That's about 526lbs below the maximum gross weight allowance for the existing airframe. The only mods would be installation of tip tanks and replacement of the Walter 601D with the fuel cells and an electric motor. Alternatively, the wings could be redesigned to incorporate a series of 4 to 6 stainless steel tanks within a composite structure.

I'm in favor of tip tanks or drop tanks hung from the wings. The tanks in question would be 18" D x 60" L stainless steel liners with composite overwrap. To provide the industry standard 250psi storage capability (up to 125F), I figure each tank would weigh around 100lbs or so. There won't be much additional drag with proper design, especially if the braced wing is replaced with a carbon composite cantilever wing. The weight saved in the redesigned wing is offset by the tank weight, but rigidity will be greatly improved. Different capacity tanks (shorter or longer) would be available for different range options and CG would be user-adjustable by altering the fore/aft position of the tank on the wing with jack screws. We'd provide operators with a weight and balance iPhone / iPad app to allow them to properly trim their aircraft and reinforce the requirement to check W&B prior to takeoff.

After flight ops have been completed, the external fuel tanks would be detached from the wings for separate servicing or storage, away from the airframe, unused LNH3 would be returned to storage tanks and payment for the unused fuel credited back to the operator's account at his or her local FBO. The fuel lines and fuel cell would be N2 purged using a N2 bottle replenished by the fuel cell's plasma cracker.

At $1.25/gallon for LNH3, our IE fuel cell / Magnax electric motor powered Comp Air 8 would cost $168.75 for a full tank (135 gallons).

At $3/gallon for Jet A, then the Walter 601D turboprop powered Comp Air 8 would cost $540.00 for a full tank (180 gallons).

Jet A is actually around $4.00 to $6.25 per gallon here, but I'm waving my magic wand here. It works for Louis, so why can't I do it, too?

kbd512 · 2019-03-30 14:13:33

Louis,

I finally found that flying monorail thing. Apparently, this was an idea from a Russian engineer named Dahir Semenov who runs an engineering firm named Dahir Insaat.

5 Future AIRCRAFT TECHNOLOGIES That Will Take You To Next Level

I kinda doubt that a flying monorail would be a more efficient people mover than a ground monorail. Physics pretty much dictates that it can't be. It looks like a passenger carrying version of the drones that Makani Power is developing with Google.

tahanson43206 · 2019-03-31 07:35:36

For kbd512...

First, thanks for finding this interesting video, and particularly the flying monorail concept.

Second, would you be willing to extend/expand your comment about physics, in the quote below?

My first impression was: "Neat Concept". On the positive side, if the plane loads at an airport and flies to the monorail, then loading efficiency would be comparable to whatever passes for efficiency with air travel today. However, the point here is that loading and offloading can take place at existing facilities without need to build passenger facilities at the monorail.

Again on the positive side, the "rolling stock" of a monorail line is eliminated for the portion of passenger traffic that is not handled by actual monorail cars.

Thus, maintenance can be carried out at existing aircraft facilities, again assuming the plane can fly some distance under its own power.

On the negative side, it seems to me that weather will necessarily factor into the success of a venture based upon this idea. There is not a lot of margin for error if the vehicle is flying at a decent speed just a few meters above the terrain.

Back on the positive side, the monorail for delivery of power ** should ** be less expensive to install and maintain than the track for a bullet train.

Again on the positive side, precision of track and equipment ** should ** be less demanding than would be the case for a bullet train.

On balance, after going through this little exercise, I am coming away thinking that a hyperloop system (as I understand the concept) might come out better in a detailed analysis.

(th)

kbd512 wrote:

Louis,
I finally found that flying monorail thing. Apparently, this was an idea from a Russian engineer named Dahir Semenov who runs an engineering firm named Dahir Insaat.
5 Future AIRCRAFT TECHNOLOGIES That Will Take You To Next Level
I kinda doubt that a flying monorail would be a more efficient people mover than a ground monorail. Physics pretty much dictates that it can't be. It looks like a passenger carrying version of the drones that Makani Power is developing with Google.

kbd512 · 2019-03-31 15:30:37

tahanson43206,

Induced Drag
The physics problem that I referenced relates to induced drag and parasitic drag created to propel an object through a working fluid. Creating aerodynamic lift with an airfoil of any kind generates induced drag or lift-induced drag. Creating thrust from a propeller, rotor, or fan to propel an aircraft also generates induced drag, as all are just applications of airfoils. It's an exponential function that decreases, the faster you go.

Minimizing Induced Drag
The induced drag penalty must always be paid in order to generate sufficient lift to fly at a given speed. Ultimately, induced drag is entirely a function of total vehicle and payload weight. Therefore, it is extremely desirable to make the vehicle's airframe and propulsion system as light as is practical while still adequately resisting the various aerodynamic and gravitational loads applied to the airframe's structure over the intended design life of the vehicle. This is typically done using a combination of structures geometry and materials that have superb strength-to-weight ratios and stiffness.

Parasitic Drag
The act of pushing something through a working fluid also generates parasitic drag. That's the drag created by pushing aside the molecules of the working fluid to propel the object through the working fluid. In this case, the working fluid is air. It's an exponential function, but it increases, the faster you go.

Minimizing Parasitic Drag
The entire purpose behind the laborious design process to create aerodynamically shaped vehicles is to minimize parasitic drag for a given design / operating speed. That is why aircraft that fly at high speed are shaped more like rifle bullets than teardrops, in order to reduce the performance penalty associated with increasing parasitic drag. If the aircraft was designed to operate at low speed, then the parasitic drag penalty from shaping the airframe more like a teardrop is low and shaping it more like a rifle bullet would increase the weight of the airframe, which creates a more significant performance penalty than parasitic drag at low airspeeds.

Total Drag
There's a "sweet spot", if you will, where both induced and parasitic drag, or total drag, is minimized. For an aircraft designed to fly at a given speed, if you fly faster than that speed, then your parasitic drag goes up and your induced drag goes down. If you fly slower than that speed, then your induced drag goes up and your parasitic drag goes down. Either way, there's a performance penalty to pay, meaning your vehicle requires more power to maintain a velocity greater than or less than its optimized design speed.

How Weight Affects Drag
If it wasn't already highly emphasized enough, weight affects absolutely everything about the design of an aircraft because it affects how much induced drag is required to fly. We want as little total weight as is practical for a given design speed and payload weight. We can't make people substantially lighter, even though physical fitness has plenty of other benefits. Thus, aircraft designers strive to make their aircraft as light as they possibly can and as strong as they need to be, but no stronger.

Power Requirements
The amount of power required to fly at a given speed also goes up exponentially as speed increases. All other factors being equal, which they never are, the amount of power required to fly at 200 knots is not 2 times what was required to fly at 100 knots, it's 4 times as much. If 100hp was required to fly at 100kts, then 400hp is required to fly at 200kts. It shouldn't take much time to figure out why a flying train that's several times larger than the largest passenger jets and likely heavier than a fully loaded airliner, with a wetted area that's many times that of a prototypical ground-based high speed monorail, yet somehow moving at greater speeds, is grossly impractical, presuming efficiency in operation is a consideration at all.

The Flying Monorail Design Problem
To the extent that I know how to do so, I've attempted to convey some basic aerodynamics concepts in layman's terms for better general understanding. For full disclosure, I'm not an aerodynamicist. In this case, I don't really need to be to know what the outcome will be. Even someone with rudimentary understanding of the basic concepts at play can deduce what the results will be. No advanced degrees in aerodynamics are required here.

With that very basic knowledge of aerodynamics, as it relates to drag and the power required to overcome it, let's consider the specific proposal from Dahir Insaat and how well it would perform if power generation for either a ground-based or flying monorail system was a design issue. My assertion is that total power required is always a design issue. So... Let's consider two variants of this monorail system, one that rides on a track on the ground and another than must somehow generate sufficient lift and/or thrust to remain airborne and carry a similar payload.

The first variant has four wings the size of those found on the A380 to provide lift, a slew of electric motors sandwiched between the wings to provide sufficient thrust for a vertical takeoff, and massive mechanisms that rotate the entire wing and tail surfaces.

The second variant has the same fuselage as the first, but no wings, tails, or electric motors to provide propulsion. It still runs on a monorail track, but instead uses electromagnets to lift the train body off the ground and propel it forward using the same current from the ground stations that would provide power for either system.

Q: Which system requires less power / weight / complexity to propel the fuselage / train body to a given velocity, the one without the gigantic wings and electric motors creating induced drag or the one with wings and propellers?

Hint: Anything you move through a fluid requires power to move it through the fluid. The more frontal area and weight, the more power is required.

My Conclusions
This is a fun thought experiment, much like battery powered aircraft, but absurdly impractical using existing technology. The only way we can manage to make these thought experiments work at all in the real world is to drastically improve the strength of the airframe, lower the achievable airspeeds, and drastically improve the power-to-weight ratio of the batteries or offload the power provisioning system entirely.

The entire purpose of such "proposals", or plain old "magical thinking" to people with a rudimentary understanding of the physics involved, was to generate buzz or funding for the company(s) that came up with the CGI animations.

Well, guess what?

Mission accomplished.

We have people who are clearly completely unaware of what's involved to make these proposals work talking about them as if it were some realistic design possibility.

Given enough thrust, we can make an aircraft loaded with Lead fly. However, it won't fly very well. A couple of Russian or European kids made a YouTube video where they experimented with a Lead-acid battery and a Lithium-ion battery in a small RC aircraft to show the performance differential with the greatly increased weight of the Lead-acid battery in the exact same airframe. The aircraft leapt off the ground in about twenty yards with the Lithium-ion battery. The same aircraft struggled to attain flying speed with the Lead-acid battery more than a hundred yards down the road, shortly before it crashed on take off. In a given airframe, adding more weight swiftly degrades performance.

Q: So, if we can make a small drone fly so well with a Lithium-ion battery, why can't we make passenger aircraft fly well using the same battery technology?

A: Power-to-Weight Ratio

The power loading, aerodynamic, and structural loads applied to something as small as a model airplane with a small battery, circuit board and servos, and nothing else onboard is minuscule compared to the amount of power and strength required to lift multiple people into the air. The power-to-weight ratio achievable with all current batteries is a joke when compared to a gas turbine or piston engine. Aircraft, unlike cars, require high continuous power output.

The 5 seats (includes 1 driver) Tesla Model S (P100D variant) weighs 4,960lbs (without passengers). If you remove the electronic governor, you can hit about 200mph. At that speed, your battery pack has a matter of minutes of charge. I doubt you'd make it 100 miles at that power output level. The Model S battery pack weighs 1,056lbs and stores 100kWh.

The 10 seat (includes 1 pilot) Pilatus PC-12NG weighs about 10,450lbs (full fuel and passenger load), so roughly twice the weight of the Tesla if you include the passengers in the weight of the Tesla. This particular bird cruises at over 300mph and can cover just over 2,120 miles at best cruise speed with sufficient fuel reserves for VFR flights. The full fuel load weighs 2,704lbs. At that weight, an equivalent set of 66lb Tesla battery pack modules would provide 256kWh worth of electricity. However, the PC-12NG comes equipped with a 1,200shp (895kW) PT6A turboprop.

Math Problems for Daydreamers
This is one of those dreaded "word problems", but doing a little math won't kill anyone. I promise.

Problem Statement:

An aftermarket aircraft conversion company creates a new battery and electric motor powered variant of the Pilatus PC-12NG. This variant stores 256kWh worth of electricity in its Tesla Motors battery packs instead of 2,704lbs of Jet A used by the turboprop powered variant. To achieve equivalent takeoff performance and flight speeds, this new electric aircraft is equipped with a Magnax 895kW electric motor as a like-kind power plant replacement for the PC-12NG's Pratt & Whitney Canada PT6A-67P turboprop. The takeoff weight of both aircraft is identical and we're assuming that the turboprop powered variant doesn't get lighter as it burns fuel, unlike what happens in real life. Therefore, both aircraft fly at the same cruise speed, at the same weight, using the same amount of power.

Over a prototypical 575 mile trip, the average turboprop-powered PC-12NG burns about 66 gallons / 448.8lbs of Jet A per hour and achieves an average flight speed of 305mph. Assuming a SFC of .67, which is what Pratt & Whitney Canada claims for their PT6A turboprop engine, that works out to an average power requirement of 669.9hp or 498.9kW. Flight time works out to 113 minutes and fuel burn is 124.3 gallons, or just over 845.2lbs.

Q: Assuming an average power requirement of 498.9kWh/hr, how long can the new electric PC-12NG fly at a cruise power level before its battery pack is completely depleted?

A: Write your answer here and show your work. Round to the nearest minute of total flight time possible.

Extra Credit:

Calculate the amount of additional capacity required from the electric PC-12NG's battery pack, in terms of kilowatt-hours, for a battery pack of the same weight to achieve equivalent flight time and speeds.

Extra Credit Hints:

There was a reason that Elon Musk stated that batteries for passenger aircraft need to achieve around 500Wh/kg to 600Wh/kg. He didn't pull that number out of his rear end. For this particular application, we need significantly more than that to reach parity. There are single-use or primary batteries that do achieve the kind of power-to-weight necessary for this application to provide similar or equivalent flight time at the same flight speeds, but that would be an inordinately expensive proposition. Our only other recourses are to decrease the weight of the airframe to permit a heavier battery with more capacity to be carried onboard or to decrease our useful load. Those options come with the added disadvantage of either requiring an entirely new airframe to be designed, built, tested, and certified for use or carrying fewer passengers, making each flight more expensive and likely requiring more aircraft to provide service for the same number of passengers.

It should also be noted that aircraft require less fuel to achieve equivalent flight speed as they burn through fuel in flight. Thus, the actual flight times achievable with batteries will be less than our simple example problem indicates. That's a feature of gasoline and kerosene burners that doesn't apply to battery packs, although it also applies to fuel cells. Since the weight of a battery powered aircraft remains constant, it's actually easier to compute range and flight speeds. There are some partial work-arounds we could use, such as modular battery packs, but we're already range-limited. There was a reason that I opined that using fuel cells and a lighter but reasonably storable chemical fuel, like NH3, to use as a reactant in a more efficient fuel cell, as compared to combustion engines, was a more viable option than current battery technology. It wasn't random, nor was it based upon personal preference.

Edit: tag:fundamentalsofpoweredflight

Last edited by kbd512 (2019-04-02 10:55:09)

tahanson43206 · 2019-03-31 17:14:19

For kdb512 re #21 ...

Thank you for this concise, understandable essay on the physics that confronts the designer of a winged vehicle, especially as compared to a train able to carry the same number of passengers.

This essay is another in a long series you have composed for the NewMars forum over several years.

Not for the first time, I wish you would edit the post to include a simple search term suitable for use with the limited search tool that comes with the FluxBB system.

If you look at posts I have chosen to make findable, you will see that I have found a system that works reliably with the search engine built into FluxBB. You would be able to find a similar method, perhaps better suited to your purposes.

An example of why I would appreciate your taking this extra step ... a while back, when hurricane(s) threatened members of the forum, you wrote one of the best examples I have ever seen, of a checklist for a family having to leave home to avoid disaster.

Over the months I have been reading the forum, I've seen a number of very high quality articles by yourself, by JoshNH4H, by GW Johnson, and others, almost all of which flow backward in time and out of view, and out of easy retrieval due to the limitations of the FluxBB search tool.

(th)

SpaceNut · 2019-03-31 17:50:31

That is what the old memory farts are for....
Some of the difficulty is the forum has changed at a minimum of 5 times; over the years, with this one staying the longest.
We also suffered a crash from 2008 through 2010 when the forum had a hard time getting back up and running.
Search terms are always difficult, in that not only is the word choice important but word order as well for finding what you really are looking for.

kbd512 · 2019-04-01 19:45:46

SpaceNut,

If there's a way to associate tags with that post, then it should probably be something like "Fundamentals of Powered Flight".

There were two very useful books that my CFI made me purchase:

Pilot's Handbook of Aeronautical Knowledge <- This is the one you want to read to understand the fundamentals of flight

Airplane Flying Handbook <- If you fly, then you'll want to read this one, too

Don't take my word for it. Read the books. They appear to be more recent revisions of the books that I have.

Post #21 can be summed up with this Q & A:

Q: Why do I want an aircraft to be as light as is practical, yet still strong enough to stay in one piece?
A: To reduce induced drag from generating enough lift and thrust to fly and to fly again another day. There have been aircraft, such as Scaled Composites' Voyager and Global Flyer that were designed by Burt Rutan, that were built strong enough for one record-setting flight. The weight associated with carrying enough fuel to circle the globe without refueling, on razor thin structural margins, was so punishing to the airframes that those aircraft were considered scrap after their record-setting flights. That is why both are now hanging from the ceiling of the Smithsonian like Christmas tree ornaments. As Elon Musk is often quoted as saying, if we built aircraft that could only fly once, then nobody would fly because it'd be too expensive. Although Mr. Musk's point of argument was directed at rockets that are routinely tossed into the ocean after a single use, it also applies equally to all other aircraft.

Q: Why do I want an airframe shape appropriate for a given design / operating flight speed?
A: To minimize parasitic drag since there's only so much we can do about induced drag (by making the plane lighter, thus requiring smaller wings to lift less weight into the air) if we want the plane to fly at a given speed and still be durable / reusable. If we want the plane to efficiently go faster, then we need higher aspect ratio wings and empennage and a more slender fuselage. If we want the plane to efficiently go slower, the we need lower aspect ratio wings and empennage and a fatter fuselage. In both cases we're making aerodynamic and weight compromises that are most appropriate for specific design flight speeds.

Q: Why is so much power required to fly at high speed?
A: To overcome exponentially increasing parasitic drag as speed goes up. If everything else is equal (even though it never is), then doubling the flight speed means quadrupling the drag. To overcome the drag associated with flying faster, the power loading must quadruple without increasing the weight. That's a pretty tall order for any engine. In practice, this means that fast jets guzzle fuel just to maintain airspeed. The fuel consumption rate is partially offset by flying higher, where the air is thinner, so there are fewer molecules of air to push out of the way as the aircraft moves through it. Oddly enough, faster aircraft actually end up being cheaper to operate (assuming you're using the aircraft to get from Point A to Point B, rather than trying to stay aloft as long as possible) by reducing flight times and associated fuel consumption since drag is always acting upon the airframe whenever the aircraft is flying. If you want to stay aloft as long as possible, then you need to fly slower to reduce fuel or energy consumption. Either way, physics will only ever be overcome elegantly using finesse, rather than brute force.

Q: Which is more important, induced or parasitic drag?
A: Neither, but it also depends on your design's intended flight speeds. The relationship between the two is inverse, which means increasing one typically decreases the other and vice versa. However, there's also a "happy medium" where both can be minimized. If you want to fly efficiently, then after you decide what speed and payload your bird will carry, you're going to optimize your airframe and power plant design to sit inside that happy medium box at cruise speed, while still retaining reasonably good flying qualities at lower airspeeds.

Q: Would it be correct to assume that there are inter-related and synergistic effects at play here?
A: Yes, it would. You can design an airframe that flies quite well at high speeds, but generates insufficient lift and has insufficient control authority at lower speeds suitable for takeoff and landing. Similarly, there are also "never exceed speeds" or "Vne" speeds for very good reasons, above which airframe structural damage is likely to occur. Designing an aircraft that can easily exceed Vne in level flight is akin to designing a death trap. Designing a plane that only generates sufficient lift to leave the ground at 300mph, but flies like a dream at 900mph, is also akin to designing a death trap. Don't design death traps. You want your pilot to be able to take off and land at reasonably low airspeeds to give him or her sufficient time to make the necessary corrections to maneuver during those critical and potentially dangerous phases of flight. Sit in the cockpit with a pilot some time when he or she is coming in at 150knots to get an idea for how long he or she has to adjust the attitude of the aircraft in order to get the bird on the ground. It's an incredibly short period of time. Ask yourself if you'd have sufficient time to correct if you had an in-flight emergency. A good pilot will exercise superior judgement to avoid having to demonstrate superior airmanship, but a prudent designer won't allow them to be put in a position where every flight is a severe skills test.

Edit: tag:fundamentalsofpoweredflight

Last edited by kbd512 (2019-04-02 10:54:46)

tahanson43206 · 2019-04-02 07:22:17

For kbd512 ...

Would you be willing to try an experiment for rapid retrieval of your writing?

The FuzzBB search engine cannot process the tag you have proposed as written.

However, I'm "pretty sure" it will succeed if you go to the post in question, Edit the post and add:

tag:fundamentalsofpoweredflight

Someone who remembers your post and wants to find it later can put into the search engine:

tag: and :fundamentalsofpoweredflight Author:kbd512

Select Post (instead of Topic)
Submit

I would be happy to test this if you would like to try it.

(th)

kbd512 wrote:

SpaceNut,
If there's a way to associate tags with that post, then it should probably be something like "Fundamentals of Powered Flight".

Last edited by tahanson43206 (2019-04-02 07:24:21)

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