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#1 2019-04-06 00:44:00

kbd512
Administrator
Registered: 2015-01-02
Posts: 3,771

Autonomous Passenger Carrying Electric Aircraft

I've started a separate topic to discuss a new potential air transportation technology that is of great interest to Louis, namely autonomous passenger carrying electric aircraft.  He prefers to call them "Passenger Carrying Drones" or "PCD's".  No matter what anyone chooses to call them, they're still aircraft that are subject to air transportation regulations.  Using new buzzwords typically has little effect on government regulations.

There was a company in years past that sold what was effectively a sound suppressor for various firearms as "Solvent Traps" or "ST's", but a federal court found, upon hearing a case brought before it by the Bureau of Alcohol, Tobacco, Firearms, and Explosives that it was in fact a "Sound Suppressor Component" or "SSC" that was prohibited from sale without the proper federal tax stamps for manufacture and sale of sound suppressors or sound suppressor components.  Firearms trivia aside, I rather think his PCD's will be determined to be "Rotary Wing Aircraft" or "RWA's" by the Federal Aviation Administration, and regulated as such.  Those of us who fly proper aircraft tend to refer to helicopters as "infernal contraptions that beat the air into submission", but who doesn't love a good acronym?

At present, no PCD's are in commercial operation.  That could always change in the future, provided that a product actually comes to market for a reasonable price and without regulations that severely limit its utility.  Given that a very useful single seat fixed wing aircraft called the Aeromarine Merlin PSA (Personal Sport Aircraft- yet another one of those acronyms) can be had for about $38K decked out with everything and professionally painted, I think something in the $50K price range or less is in the right ballpark.  The Bye Aerospace SunFlyer 2 / eFlyer is priced at $349K.  That's about what you'd expect to pay for a brand new Cessna with similar capability.  A brand new 2 seat Robinson R22 helicopter will set you back about $250K and their 4 seat R44 model will come in around $375K.  Most individuals and small businesses can't afford new aircraft, so many buy used aircraft at significant discounts.  A used R22 in flyable condition is $100K or less, for example.  In the aviation world, you actually don't want a used aircraft that hasn't been flown on a routine basis for a one word reason-  "corrosion".

I also think a lot of laws must change first.  Any aerial vehicle that is 100% autonomously operated would place nearly 100% of the liability on the product manufacturer since there is no actual operator.  Even if the product manufacturer was successful in developing, marketing, and mass manufacture of such a vehicle, any incidents not handled by the autonomous system would likely result in the fledgling PCD manufacturer being sued out of existence.  There's a lot of shared liability in the aviation world that doesn't exist in most other businesses.  Anyone who thinks there will never be any accidents following an explosion in the number of passenger carrying aircraft taking to the skies isn't fooling anyone else.  It'll be a liar's, I mean lawyer's (for some reason I always confuse those two), dream come true.

It's rather odd that Louis places so much faith in computers when it is humans who program computers and humans who make computers, but humanity routinely proves that logical consistency is not required to become enamored with any particular idea.  Computers do perform repetitive tasks with greater accuracy than humans in most cases, but the instant an input or chain of events not conceived of by the software engineers happens, the results are unpredictable.  That is not to say that reasonably reliable systems can't be created through concerted effort, but it's not as easy as some think it is.  Whether people are aware of the inherent complexity in software, electronics, and computers, or not, that complexity is quite real.  Jet engines seem complex until you realize that the Full Authority Digital Engine Control (FADEC- you can never have too many) software programs that run them contain many times the number of parts spinning inside the engine.  Through my work, I'm all too familiar with the potential problems associated with complex software-defined systems.  Thankfully, no lives are on the line in what I do, just tens to hundreds of millions of dollars.  Money can be replaced, but lives cannot.

There are already numerous small electric drones in operation that deliver packages and monitor or inspect anything that benefits from aerial observation.  As the years go by, the proliferation of the technology will only increase.  As such, it warrants its own discussion and consideration.

I remain skeptical of this new technology because we've been promised personal aerial transport for many decades and a practical vehicle has yet to materialize.  There are no insurmountable technological challenges, yet the number of companies that have tried and failed to deliver this revolutionary new technology are too numerous to count.  If it truly was a simple and easy thing to do, it would've been done by now.

There has been precisely 1 vehicle that was licensed as a street legal car by NHTSA and as a certificated aircraft by FAA.  That was Molt Taylor's Aerocar.  I can't recall the exact year it was certified, but it was in the late 1940's or early 1950's.  Fewer than a dozen were ever built.  Strangely enough, the PSA that I'm building is a Molt Taylor Mini-Imp.  Will that change in the years to come with computerized drone technology?  I certainly hope so, but I've seen so many failures over the years that I won't hold my breath waiting for it to happen.

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#2 2019-04-06 05:17:26

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,875

Re: Autonomous Passenger Carrying Electric Aircraft

Ehang are well advanced with their PCDs:

https://gulfbusiness.com/video-dubai-fl … st-passeng

Lots of drones in the race:

https://www.dronerush.com/drone-taxi-pa … nes-10666/

I think it's a mistake to think of a PCD as a flying car - I don't see it that way.

I am sure someone else must be thinking of a battery changer appraoch to extend range...we'll see.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#3 2019-04-06 06:58:06

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 3,773

Re: Autonomous Passenger Carrying Electric Aircraft

For Louis ...

In another topic recently, SpaceNut re-introduced the idea of feeding energy to flying vehicles using RF (radio frequency) transmission.  Antenna can be incorporated in the underside of a vehicle.  At this point I don't have a strong sense of how much power can be transferred using this method, but I doubt it is much.  Building a ground station for this purpose would be quite an effort, and you'd need a lot of them.

SpaceNut/kbd512 showed us recently, in another topic, a Russian design for a passenger aircraft that would (as I recall from the image) drag an umbilical cord which is engaged with an electric supply monorail structure to provide power for the vehicle. 

I thought at the time that an RF feed would "work" about as well.  Of course, that would mean "not very well".

(th)

Last edited by tahanson43206 (2019-04-06 08:38:40)

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#4 2019-04-06 13:23:28

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,902

Re: Autonomous Passenger Carrying Electric Aircraft

The personal plane car falls into the category but the link indicates a sub size for ultra light when it comes to stripped down air traffic.

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#5 2019-04-06 16:49:55

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,875

Re: Autonomous Passenger Carrying Electric Aircraft

I previously referenced induction recharging of passenger drones but thinking about it I concluded battery changing would be the perfect technology for drones. With the right design I doubt a battery change would take more than 90 secs.   

I think anyone who has experienced contemporary air travel knows "taxiing on the runway" often takes 10, 15, 20 mins. 

Battery changing would overcome the range issue on land at least.


tahanson43206 wrote:

For Louis ...

In another topic recently, SpaceNut re-introduced the idea of feeding energy to flying vehicles using RF (radio frequency) transmission.  Antenna can be incorporated in the underside of a vehicle.  At this point I don't have a strong sense of how much power can be transferred using this method, but I doubt it is much.  Building a ground station for this purpose would be quite an effort, and you'd need a lot of them.

SpaceNut/kbd512 showed us recently, in another topic, a Russian design for a passenger aircraft that would (as I recall from the image) drag an umbilical cord which is engaged with an electric supply monorail structure to provide power for the vehicle. 

I thought at the time that an RF feed would "work" about as well.  Of course, that would mean "not very well".

(th)

Last edited by louis (2019-04-06 17:10:57)


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#6 2019-04-06 17:31:27

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 19,902

Re: Autonomous Passenger Carrying Electric Aircraft

Repeditive quick recharge is a problem for batteries in general as the internal heat from charge has no place to go and that is what destroys a battery. Now if a battery can have a means to keep the internal heat down via some sort of inner chamber for cooling gas or liquid to be used in order to remove heat them they can last.

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#7 2019-04-07 20:01:29

kbd512
Administrator
Registered: 2015-01-02
Posts: 3,771

Re: Autonomous Passenger Carrying Electric Aircraft

tahanson43206,

Credit Where Credit's Due
Louis introduced the concept of the flying monorail and I simply fetched a link to it.  I merely stated what was obvious- namely that a ground based monorail is a lot smaller, uses a lot less energy- even if it travels at the same speed, and is unlikely to crash into someone's office building or home located near the monorail track.  Try to imagine the thrust that something the size and weight of a train would need to generate to hover and what would happen to anyone or anything on the ground, mere feet below it.

Sea Story Time
The F-35B's powerful engine would pick up and toss anyone unlucky enough to be underneath it like a rag doll.  That's why you see flight deck crews standing well clear of the exhaust on amphibious ships.  It's dangerous.  A jet from my squadron picked up and tossed a guy over the side of the carrier by merely throttling up just enough to taxi the jet.  He broke his leg when he hit the pole connected to the netting around the deck that was supposed to catch him on his way to the water- 80 feet below.  Word to the wise, if you ever jump off a carrier, you'd better make sure both of your legs and arms are working.  The few times I did it, I was below the keel before I started coming back up.  Seeing the hull of your ship above you is a very strange thing.  Anyway, I later met him as a civilian (never even knew who he was while we were in) working an office job for GM.  He broke his leg on one of our slick ladders (everything is covered with residue from jet exhaust) leading to the flight deck while we were deployed, he healed, he was sent back out while we were still deployed (I think we were approaching the record for number of days at sea that was set in WWII), one of our jets blew him off the ship after he returned, he broke his leg again on his way down, and then he was medically discharged after medical treatment.  The exhaust from A-6 Intruders and EA-6 Prowlers is angled down into the flight deck, unlike all other Navy jets that are straight to the rear.  You can't run behind the jet and duck the exhaust the way you can with a Hornet or a Tomcat.  That's a long winded way of saying don't stand behind Intruders or Prowlers or bad thing will happen.  Both jets are now retired and replaced by the Hornet, Super Hornet, and F-35C.  Imagine the thrust produced from multiple squadrons of F-35's at full power, and now you understand why it is that a flying monorail won't work in an urban area, or any other area with people / plants / animals (flying cows and cars, anyone?).

First-Hand Experience with Excessive Thrust
The US Navy tried to replace the SH-60 Seahawk with the V-22 Osprey, but quickly discovered that the downwash from the V-22's massive rotors was so powerful that it could push those below it into the water and drown them while it hovered low enough above to deploy rescue swimmers (swimmers jump out of the helo at low altitude) to retrieve lost crew members and downed pilots.  Generally speaking, we try to drop swimmers right next to someone because that minimizes the time it takes to effect a rescue.  This flying monorail would make a F-35B or CMV-22 seem like a child's toy.  Trains were never meant to fly.  The V-22 and F-35B hover by generating enormous amounts of thrust, which consumes enormous quantities of fuel.

DJI makes a quadcopter drone that carries a 5 pound payload.  It flies for 13 minutes.  A drone that uses a wing to carry the same 5 pound payload flies for 100 minutes with the same battery capacity.  Is it apparent why I said a supersonic electric VTOL would be a craptastic aircraft?

PteroDynamics TransWing

If people are dead set on using these electric VTOL machines, then the link above demonstrates how you'd actually do it economically.  The Germans had the right idea in WWII.  This is nothing more than a refinement of Weserflug's "P.1003" concept.  Notice that the cost of both drones is roughly equivalent.  That's to be expected because the cost of the batteries and motors drives weight, which drives vehicle price.

Atmospheric Microwave Power Transfer
Enormous quantities of power can be transferred at suitable wavelengths with minimal losses up to the beam breakdown distance in the atmosphere.  That would be the distance at which the atmosphere begins to ionize and absorb the radiated power.  This technology is potentially dangerous without exceptionally precisely control of the power beam.  Thanks to the nuclear fusion industrial base, we have individual emitters that can generate 10MW or more.  Toshiba makes 10MW gyrotrons, for example.  Provided that we can tightly focus the beam, the power is more than sufficient to power an airliner.  Just remember that no matter what, something has to supply about twice as much power as the aircraft engines due to microwave power transfer inefficiencies and the power supply can't fail for any reason.

ITER Newsline - Designing an antenna the size of a bus

ITER Newsline - The plasma starter

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#8 2019-04-08 08:45:47

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 3,773

Re: Autonomous Passenger Carrying Electric Aircraft

For kbd512 ...

First, I'm delighted to have inspired not one, but TWO of your recent sturdy essays!

Thanks for the sea story, in illustration of your point about forces around powerful aircraft. 

At a recent social event, set up for women who dragged their husbands and friends along, I met a gent named Matt who told be a little bit about his 20 years in the Navy.  He served on a marine carrier and a destroyer.  Next time I see him, which could be a year from now, I'll tell him about your presence here, to see if I might be able to promote an exchange of stories. 

Regarding the subject at hand, which I readily concede you have dealt a mighty blow, if the idea is to try it in the US, I would like to remind you of the context.

The context is Russia!  The local paper ran a story over the weekend, about a base (one of many) that Vladimir Putin is setting up in the Northern perimeter of Russia, to guard the (expected/predicted) vast wealthy of the Arctic Ocean.  The story was about life in one of the bases, which are so similar to what we've been talking about here for Mars, that I was taken aback.  The entire livable area is underground.  No one goes outside if they can help it.  Obviously, this is a military base, so the troops "can't help it" << grin >>.

However, this glimpse of what Putin is doing, and a reminder of the vast unpopulated reaches of the land area of Russia, reminds me of the cost-benefit ratio for deploying a ground effect aircraft to move freight and people across thousands of kilometers.

The cost of a power rail for aircraft to cover this kind of terrain would be less (I'm not sure how much) than the cost of a rail system to support a train.  The rail support structure does not have to bear load other than itself, which would put it in the category of pipelines built above ground.

In short, if you can put yourself in the mindset of Mr. Putin (Admittedly not something easy for most of us), you will find the prospect of the electric plane supply line to be of interest.

***
To avoid creating a separate post, I'll point out here that your reply to my offering about a potential technology wave did not appear to address that theme, although your post did add to your previous support of ammonia as a viable energy delivery medium.  That post included mention of the need for efficient systems to extract hydrogen from ammonia, and while I'd have to go back to confirm my recollection, I believe a group in Australia has made significant progress in that specialty.

What I'm looking for is a change of the entire infrastructure of power tools, appliances and even home energy support systems based upon conversion to ammonia as an energy carrier for the long term.

Ammonia can be produced offshore in many locations remote from human habitation, and delivered (ultimately by pipeline) to individual homes and businesses in first world nations able to invest in the infrastructure.

The economic wave I see as possible would be comparable in size to the railroad industry of the past century, and the aircraft industry today, or the Natural Gas industry of the present time, which includes LNG and LPG ships crossing the Panama canal every day.

The potential exists for those ships to carry ammonia in comparable quantities, and to do so based on renewable feeds, as stored hydrocarbons are exhausted, as they inevitably will be.

(th)

kbd512 wrote:

tahanson43206,

Credit Where Credit's Due
Louis introduced the concept of the flying monorail and I simply fetched a link to it.  I merely stated what was obvious- namely that a ground based monorail is a lot smaller, uses a lot less energy- even if it travels at the same speed, and is unlikely to crash into someone's office building or home located near the monorail track.  Try to imagine the thrust that something the size and weight of a train would need to generate to hover and what would happen to anyone or anything on the ground, mere feet below it.

Sea Story Time
The F-35B's powerful engine would pick up and toss anyone unlucky enough to be underneath it like a rag doll.  That's why you see flight deck crews standing First-Hand Experience with Excessive Thrust
Atmospheric Microwave Power Transfer

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#9 2019-04-08 12:07:34

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,875

Re: Autonomous Passenger Carrying Electric Aircraft

Kbd,

I never raised the concept of a flying monorail...I raised the idea of an induction rail that a PCD would hover over and perhaps move along slowly (so that other PCDs could file in behind) while recharging the battery.

I was being a bit thick when I saw the monorail-plane vid you posted - I didn't realise that link you posted to showed an electric plane being powered by the line connecting it to the monorail! That was probably because at the time I was focussed on crossing the Atlantic in PCDs so didn't feel the monorail was v. relevant. Anyway the electric plane monorail idea seems supremely impractical to me...apart from the exhaust issues and the noise, you'd be back to all the costs of an HST line with disadvantages that HST doesn't have (trains are not much affected by high winds whereas the monorail plane would be - would like be unable to fly in some high winds).

To return to PCDs...I think 90 sec battery changes would revolutionise PCD travel. It would certainly make nationwide journeys practical.  As for intercontinental travel that might require further innovation.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#10 2019-04-08 14:02:08

kbd512
Administrator
Registered: 2015-01-02
Posts: 3,771

Re: Autonomous Passenger Carrying Electric Aircraft

tahanson43206,

Acceptance of What Works for Aviation Applications
Whereas I accept the limitations of current and projected near-term battery technology, Louis does not.  We have power technologies that can enable electrification of these new transportation and energy storage concepts, if only we accept what current technology has to offer.  I happen to agree with Louis in principle, but current technological reality is what it is.  He'd rather wait and hope for something better to come along.  If we do the former, then we can secure a revitalization of air, rail, and ship transportation that profoundly alters the current paradigm.  If we do the latter, then we may have to wait many more decades for better batteries to become available.  Both nuclear fission and fuel cell technologies are bridge technologies to something better.  Use what sound aerospace engineering can actually deliver today using novel materials and existing power generation technologies, not what science promises to provide for that gleaming world of tomorrow.  The gleaming world of tomorrow only gets built with real technology.  That's a very long-winded way of saying "We gots what we gots and we ain't got no more."  We need to try new things that at least have a chance of producing better results.

Estimating Cost
Cost is easier to estimate than it is to provide exact figures for.  That said, any vehicle that flies will almost certainly be more expensive than a vehicle that doesn't.  The act of making a vehicle that flies predictably (good handling qualities) and reliably (very few crashes) is not something that can be accurately estimated.  There are invariably discoveries along the way that initial testing did not uncover.

Computers Are Not A Panacea
The Boeing 737 Max 8 and Airbus computerized flight controls are prime examples.  Both systems have caused the crashes they were intended to prevent.  The real question should be why Boeing did not learn from the Airbus experience with the same type of problem.  The entire reason that MCAS exists was by government mandate.  That's just another example of how government create artificial problems for others to solve.  The FAA was worried that because Boeing moved the engines further forward to adequately clear the ground, that would create pitching moments leading to out-of-trim stalls that the pilots wouldn't be able to recover from.  The reason you push the nose down first and then apply more power if you're close to stalling is that pushing the throttle lever forward causes the nose to pitch up.  Sadly, the very system that was intended to prevent that set of circumstances from taking place using computerized control over the trim control surfaces has directly caused fatal out-of-trim events.  The pilots responses exacerbated the problem, but all pilots are new to the aircraft because it's a new aircraft.  If the plane was completely computer-controlled, then there's no question at all that it would've crashed and never even made it as far as it did with the pilots fighting the computers for control.  If MCAS was never present to begin with, this problem wouldn't exist.  When your aircraft is grossly out-of-trim, it may be difficult to impossible to generate enough force (use muscle power to overcome the aerodynamic and hydraulic forces acting on the control surfaces) on the trim wheels or the control column to re-trim the aircraft.  Pushing the nose in the direction of the trim unloads the force on the control surfaces enough to re-trim by hand.  At low altitude and/or with sufficiently high airspeed, you don't have enough altitude and time to trade to sort out the trim problem.  Trim settings are one of the items on the checklist prior to takeoff for that very reason.  You may not have enough altitude, airspeed, or time to fix it later.  There's nothing quite as useless as airspeed you don't have, altitude above you, or runway behind you.

Human Operators Still Required for Mass Aerial Transit
The moral of the story is that the results of computerization is only as good as the input data fed into the computer and the reliability and accuracy of the instruments that the data comes from.  In a vehicle that is completely computer controlled, garbage in almost always equals crash out when that vehicle flies.  It's an object lesson in the limitations of computer programming.  It's mathematically provable that no matter how simple or complex the program, it is physically impossible to write a program that can accept any input and continue to run in a loop.  Anyone who believes that computer programs can be made infallible through careful programming should think long and hard about that.  On the other hand, a good pilot can still land a plane even if the avionics are completely screwed up.  Many have done just that over aviation's relatively short history.  A computer never could, not even an AI-enabled computer, because it relies upon input.  We can do what we can do to handle input or logic faults, but there's a limit to what can actually be done.

Ammonia Delivery Infrastructure
Long term, I can see NH3 delivery to homes to power a fuel cell outside the home to supply electricity for everything inside.  That overcomes the staggering losses from attempts to transmit electricity over hundreds of miles.  Electrical resistance is a PITA and we can't seem to find a room temperature superconductor after decades of searching, so stop fighting it just long enough to rectify the losses.  If a solution is found, it requires new infrastructure and nothing is lost.  The gas pipes are buried, so if there's a NH3 leak then maybe the vegetation above it grows a little faster.  Since the NH3 is not inside the home, a leak outside the home can be detected by the foul odor.  It's less explosive than gas and requires no methyl mercaptan additives to the gas to warn people of gas leaks.  Either can obviously suffocate and kill.  Ammonia can also be delivered to homes, transportation hubs, and industrial areas as Ammonia liquor when mixed with water.  The liquor is heated to release the Ammonia, a plasma cracker splits off the H2, and the H2 is reacted with O2 in a fuel to produce electricity.  The home fuel cell will just be another appliance outside the home, like a backup natural gas generator.  It negates the need for anything but plastic pipes or the existing steel that carry natural gas.  A fluoropolymer rubber or plastic won't rust, the liquor is only slightly basic, it's liquid at atmospheric temperatures and pressures, and the filtered water can either be recycled back to the plant to be reloaded with Ammonia or used to water plants at the home with a very low quantity of fertilizer added to it.

* CO2 emissions confined to Haber-Bosch plants that capture the CO2 to obtain virgin (uncontaminated) Carbon powder materials for carbon fiber / CNT fiber / Graphene fiber aerospace composites or electrical conductors using UV lasers.  The O2 would also be captured for industrial or transportation (rocketry, mostly) purposes.

* No more burning of coal / gas / oil to generate electricity and any CO2 extracted should be retained to supply the highly valuable and exceptionally expensive (in pure form, which is what CO2 can provide) Carbon building material to the transportation industries.

* Transportation vehicles are not loaded with explosives to make them useful (provide the same range and speed as liquid hydrocarbon fuels for a given weight).

* Carbon composites that are lighter and stronger than metals limits the need to mine more metals for construction.  This also reduces pollution since so much energy is required to obtain and refine metals to create useful alloys.  If we commit to this, then I believe we've already mined enough metals to preclude the need to mine any more.  We can continue to recycle what we have, which is an increasing part of what we do here in the US where we have so much metal.

* Eventually gas and liquid hydrocarbons will be exhausted, but for now we will use those valuable commodities to both supply the power and the building materials for next generation composites.  We will continue to develop the new solar fuel cell technologies, like those being developed in Australia, and refine them to the point that they can take over for hydrocarbons to provide a completely renewable supply.

* LH2 and LCH4 would become specialty fuels for rocketry, but the oil and gas industry would primarily feed product into the Haber-Bosch process to obtain Ammonia to load into water for transport by pipe or tank.  Polymers for rubbers / plastics / resins / lubricants would be the remaining uses for oil refineries and they already do that.  Basically, we're limiting our requirement for petroleum products to niche uses where no other technology will provide a suitable like-kind product.

* If batteries of sufficient energy density are available for a particular application, then that is the preferred method of storing electricity because it involves the least risk (highly dependent on the specific cell chemistry in question, but generally true).  As of now, they're insufficient for more than very short range flights.  Future?  Let's hope that those 1kWh/kg batteries are real and begin commercial production post-haste.  That would mean replacement of small turboprops.  It won't scale up past that, but there are a considerable number of commuter turboprops that could be swapped with batteries and electric motors when energy density hits 1kWh/kg.  The aircraft would have to have the fuel tanks removed via partial disassembly of the wing to replace with batteries, but connecting a power cable is just as easy as connecting a fuel hose.

* At 1kWh/kg passenger carrying autonomous aircraft would become practical helicopters without swapping battery packs.  It's a lot easier to connect a power cable to an aircraft than it is to remove parts of an aircraft that have significant weight, typically because those parts must be secured to the aircraft using multiple fasteners to handle the aero loads.  We don't take drop tanks off of jets without first draining out the fuel (removing the weight), for example, and those are much easier to remove than integral parts of the aircraft.  There's no way to get rid of the weight from a battery pack of significant capacity.  I see partial disassembly of the aircraft as a last resort.  Disassembly of the aircraft is known as "maintenance" in the aviation world and only permitted to be done by a qualified mechanic, whereupon completed work is double-checked by another qualified mechanic.  A 10 minute recharge would be functionally meaningless in aviation.  It takes longer than that to reload (passengers or cargo), refuel, and secure a clearance for departure.

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#11 2019-04-08 14:24:00

kbd512
Administrator
Registered: 2015-01-02
Posts: 3,771

Re: Autonomous Passenger Carrying Electric Aircraft

Louis,

I think you'd be shocked by how little space is required for a private STOL aircraft to take off and land.

Watch the Valdez STOL competition on YouTube:

Extreme STOL, Alaska style

Imagine this competition with far lighter electric motors.  It wouldn't be fair to the gas powered aircraft, but it would produce stunning results.  The O-320, while certainly not the heaviest engine around, is nowhere near as light as an electric motor that produces equivalent horsepower.  These are mostly steel and fabric aircraft.  The one that landed in 10.5 feet and took off in 14 feet is, I believe, Aluminum instead of steel.  Imagine something made of CNT tubing and fabric that's easily half the weight.  It'll fly at 90mph to 120mph far longer than any helicopter, for equivalent energy consumption, yet leaves the ground in little more than a parking space.  My Escalade is longer than that takeoff run.  It still requires far less power than VTOL, but you can literally take off and land on a roof top helipad.  Since you have lift, vs pure thrust, you're not guaranteed to immediately fall out of the sky if the motor quits running.  You need 1 motor instead of half a dozen or more.

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#12 2019-04-08 17:44:05

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,875

Re: Autonomous Passenger Carrying Electric Aircraft

Mostly for kbd I think...

1. Yes I was aware of some amazing STOL feats. I think the Germans had something called the Stork during WW2 and the allies had similar STOL aircraft for undercover missions behind enemy lines or commando work.  I don't think it's particularly relevant to PCDs. STOL I imagine is not a great passenger experience, especially for those who find flying unnerving. PCDs can ascend gently.

2.  I don't think I am overselling the ability of PCDs to fly safely automatically. Obviously it's a new technology and people are rightly cautious of giving them the green light. But we already know that self-drive cars have completed tens of thousands of miles of test drives in a much more dangerous environment - Earth's busy roads with all the sudden hazards and challenges of idiot driving, pedestrians, signage, wet roads, traffic lights, roadworks and so on. We also know all big aircraft fly most of their journeys automatically. They could probably land safely on auto pilot in fair weather as well. This isn't to say there might not be the occasional accident over a 10 year period - but at least with any such accident you have a v. low death toll of one or two compared with a passenger jet's 100-300. A multi-rotor  PCD is inherently safer than a 2,3 or 4 engine jet I would suggest.

3.  I am not sure you are right about computers requiring input (if I understand what you mean by that) - computer systems can now learn. They might not yet be able to fly by themselves, but I wouldn't be surprised if they could. A PCD would be a pretty simple thing to fly in any case. You'd probably have a couple of complementary GPS systems coupled with some topographical mapping feature for automated guidance. If anything went out of synch an automonous safe landing computer system would take over and land the craft in the nearest safe location. The rotors would be independently powered. If one went down, the PCD would execute a safe landing on the other rotors. On board transponders would prevent PCDs coming too close to each other. The PCD would have at least two discrete power systems (as in battery supply), one main and one supplemental, so if one goes down the other is available to execute a safe landing. 

4. PCDs are way simpler than even small aircraft let alone big passenger jets that have over a million parts. PCDs would be more on a par with a small car that has maybe 30K parts.  Much less to fail and much less of it critical.


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#13 2019-04-08 18:19:27

SpaceNut
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Re: Autonomous Passenger Carrying Electric Aircraft

I think that the computer input in this case could be verbal and not neccesarily via a keyboard as in where do you want to go response and if there is traffic how to avoid or determine if going slower is ok.

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#14 2019-04-08 19:11:35

kbd512
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Re: Autonomous Passenger Carrying Electric Aircraft

Louis,

1. Have you ever seen an autorotation test of any of these VTOL electric passenger drones?  If not, do you understand why that's never been demonstrated?

Here's a clue.  You can't autorotate with fixed-pitch blades.  The blade pitch is optimized for generating thrust at low speeds.  That's why they have multiple motors.  If you lose all motors, then you literally fall out of the sky.

2. You really should listen to what the man from Bell Helicopter has to say about safety and reliability of autonomous systems:

A deep dive into Bell’s Nexus eVTOL Air Taxi Aircraft of the Future – AINtv

Since he leads a design team that's actually built and is testing one of these things, we're going to presume that he knows a little bit more than the both of us when it comes to how one of these things works.

3. Any computer that is autonomously piloting a flying machine is 100% dependent upon input from sensors.  If you don't understand what that means or why it is so, then you should try to figure out where you are after a friend blindfolds you, puts ear muffs on you, plugs your nose, and puts boxing gloves on your hands and clown shoes on your feet.  I'll bet you'll have a real hard time with that.  Oddly enough, a computer would, too.  The computer "knows" what it "knows" based on good sensor input.  If those sensors malfunction, the flight control computer can't function.

The EHang 184 passenger drone has zero control authority and no ability to autorotate if power is ever lost.  That's the price you pay for having multiple less reliable, but cheaper and smaller, rotors and motors.  If power or computer control is lost, reason unimportant, there's only one direction you're going and you're not going in that direction at a survivable vertical velocity.  It's a flying coffin.  The guy who started the company had a couple of his close friends die in helicopter accidents and thought he knew better than the legion of engineers who design helicopters.  Apparently, he thinks he's making helicopters "safer" by ensuring that such accidents are completely unsurvivable if power or control authority is lost.  It's just more of that magical thinking in action.

4. You keep asserting your personal beliefs as statements of fact that are wildly incongruent with reality.  PCD's, as you call them, are not "way simpler" than small fixed wing aircraft.  They're not simpler in the aerodynamic sense, in the mechanical sense (assuming both are powered with electric motors), in the control sense, in the total system complexity sense (software and electronic complexity still counts as complexity), nor any other metric applicable to any actual aircraft.  In Point #3 you just described something that's absurdly complicated to actually design and operate in a reliable manner and then in Point #4, you completely hand-waved all that complexity away with your magic wand.

No.  Just...  No.

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#15 2019-04-08 20:25:09

kbd512
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Re: Autonomous Passenger Carrying Electric Aircraft

Airbus has also had their own share of computer control issues from faulty sensor input and software programming.  This video illustrates what happens when aerospace engineers hold religious beliefs that software programs can never be wrong and that humans are the problem.  There are no adequate substitutes for well trained and experienced pilots.

Unlike software programs, experienced pilots aren't subject to reacting to absurdities- like simultaneously over-speeding the airframe while the wing is stalling, meaning the aircraft is moving belly first through the air faster than Vne.  It's obvious to a human pilot that that can't be what's actually happening because the aircraft wouldn't still be in one piece.  The A330's software, which was obviously written by a human, was expected not to contain any human-caused errors.  That clearly wasn't the case.  The aforementioned scenario was completely impossible if the chronological timeframe of the events that never took place was also taken into consideration by the software.  The nose did not pitch up 50 degrees in a nanosecond whilst simultaneously flying faster than Vne.

Interestingly, the person narrating the video thinks that computerization is the primary reason behind reduced flight accident rates.  He's probably unaware of the fact that during the same time frame that accidents dramatically declined, concerted effort and regulations were promulgated to assure better engineering, maintenance, and training practices that have reduced crashes.  Computerization was one result from that effort.  Computers have prevented some aircraft from crashing due to human errors, but in other cases the computers were the direct cause of injuries and fatalities.  As the Captain in the video stated, "Computer control is great until it's not."  When it's not, the result is generally the same as it was before computerization.

When 'psycho' automation left this pilot powerless

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#16 2019-04-08 20:41:09

SpaceNut
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Re: Autonomous Passenger Carrying Electric Aircraft

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#17 2019-04-09 09:01:20

louis
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Re: Autonomous Passenger Carrying Electric Aircraft

1. Yes - if all motors fail - and why would all motors fail?

2. Yes and he says redundancy allows them to manufacture to lower spec for individual parts. My point, not yours.

3. Well yes any system requires input and your average pilot wouldn't have a clue where they were in fog without inputs. That's no different for a computer in principle. It's a question of how you interpret the inputs. It's easy for a computer to take account of all inputs simultaneously - much more difficult for even a trained pilot to do that, especially in an emergency.

4. I am comparing electric motor PCDs primarily with passenger jet aircraft using hydrocarbon fuels. I would disagree with your claims that they are of the same order of complexity. One way of addressing that is listing all the things that could bring down a jet aircraft and all the things that can bring down a PCD.


kbd512 wrote:

Louis,

1. Have you ever seen an autorotation test of any of these VTOL electric passenger drones?  If not, do you understand why that's never been demonstrated?

Here's a clue.  You can't autorotate with fixed-pitch blades.  The blade pitch is optimized for generating thrust at low speeds.  That's why they have multiple motors.  If you lose all motors, then you literally fall out of the sky.

2. You really should listen to what the man from Bell Helicopter has to say about safety and reliability of autonomous systems:

A deep dive into Bell’s Nexus eVTOL Air Taxi Aircraft of the Future – AINtv

Since he leads a design team that's actually built and is testing one of these things, we're going to presume that he knows a little bit more than the both of us when it comes to how one of these things works.

3. Any computer that is autonomously piloting a flying machine is 100% dependent upon input from sensors.  If you don't understand what that means or why it is so, then you should try to figure out where you are after a friend blindfolds you, puts ear muffs on you, plugs your nose, and puts boxing gloves on your hands and clown shoes on your feet.  I'll bet you'll have a real hard time with that.  Oddly enough, a computer would, too.  The computer "knows" what it "knows" based on good sensor input.  If those sensors malfunction, the flight control computer can't function.

The EHang 184 passenger drone has zero control authority and no ability to autorotate if power is ever lost.  That's the price you pay for having multiple less reliable, but cheaper and smaller, rotors and motors.  If power or computer control is lost, reason unimportant, there's only one direction you're going and you're not going in that direction at a survivable vertical velocity.  It's a flying coffin.  The guy who started the company had a couple of his close friends die in helicopter accidents and thought he knew better than the legion of engineers who design helicopters.  Apparently, he thinks he's making helicopters "safer" by ensuring that such accidents are completely unsurvivable if power or control authority is lost.  It's just more of that magical thinking in action.

4. You keep asserting your personal beliefs as statements of fact that are wildly incongruent with reality.  PCD's, as you call them, are not "way simpler" than small fixed wing aircraft.  They're not simpler in the aerodynamic sense, in the mechanical sense (assuming both are powered with electric motors), in the control sense, in the total system complexity sense (software and electronic complexity still counts as complexity), nor any other metric applicable to any actual aircraft.  In Point #3 you just described something that's absurdly complicated to actually design and operate in a reliable manner and then in Point #4, you completely hand-waved all that complexity away with your magic wand.

No.  Just...  No.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#18 2019-04-10 00:54:19

kbd512
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Re: Autonomous Passenger Carrying Electric Aircraft

Louis,

1. The half dozen or more motors are controlled through computer software because that's the only way to do it as precisely as is required to make the aircraft hover or transition to forward flight, with or without lift from fixed wings.  Imagine that you have three motors on the starboard side all producing 1% more thrust than the ones one the port side.  You could never establish a stable hover with that kind of thrust differential.  As such, there comes a point where a simple rheostat switch is no longer sufficient.  A single-engined fixed-wing STOL aircraft can use a simple lever or rheostat to control the thrust that the motor produces.  Apart from battery charge / discharge controllers that inhibit charge / discharge rates that would lead to battery damage, no sophisticated fly-by-wire software that follows flight control laws / rules is required to make that work.

All rotary wing aircraft have dynamic stability.  Constant correct control input is required to maintain stable flight, whether hovering or moving in some direction.  If the system is automated, that comes from correct sensor input that tells the computer how to adjust both power and flight control surfaces.  The drones may only use power adjustments to individual motors to maintain stable flight, rather than ailerons / elevator / rudder inputs, but constant input is nonetheless required.  It may seem simpler in concept, but it's every bit as complicated in practice.  The number of control surfaces that interoperate with each other is just as great, or greater to achieve overall reliability- which is exactly what our man from Bell Helicopter stated in the video.

A fixed wing aircraft can be trimmed by the pilot such that the aircraft maintains stable level flight without further control input.  Even if turbulence upsets the aircraft, it will resume stable flight after a brief series of pitch and/or yaw oscillations.  It's common to trim the aircraft, take your hands and feet off the controls to see if it's still flying how you wanted it to, meaning straight and level in this case, and then re-adjust as required until hands-free level flight is established.  In a Cessna, or most other simple fixed wing aircraft, you have hand-operated pitch and yaw trim wheels to do this.  The high performance ones tend to use electric servos.  If you do that, then you can mount electric trim switches / wheels / knobs on the control column.

2. My point is that instead of spending more time and money on electric motors and propellers with greater reliability and durability, they're substituting less reliable components and simply using more of them, on the premise that that will increase reliability to the point where individual component reliability is less of a factor.  Broadly speaking, the entire reason for using electric motors and batteries is greater reliability than combustion engines.  Using cheap motors / propellers / batteries defeats the purpose behind using what could be intrinsically more reliable than combustion engines.

Lycoming piston aircraft engines are not more expensive than Chevrolet car engines merely because production volume is lower.  The components are made to higher tolerances from higher grade materials (Corvette engines are a good analog, and unsurprisingly, Corvette engines are a lot more expensive), the total tolerances permissible between interfacing parts are lower (much like a race car engine or blue printed engine), every part is inspected, and the entire motor is all-up tested for several hours in a test cell before it leaves the factory.

3. The pilot can determine what information to pay attention to and what information to ignore.  It's much more difficult for a computer software program to do that.  When I write software, I do my best to make it fail gracefully.  Sometimes that's possible and sometimes it's not.  The most unpredictable results happen when both hardware and the software running on it both fail.  What am I supposed to do if the avionics hardware that controls all the motors fails?  Pray?

The entire reason we're trained to fly in adverse conditions, to memorize checklists of emergency actions, and constantly drilled on those procedures is so that we address the most important problems first.  If a computer can't figure out that flying belly first, faster than Vne, whilst the wing has simultaneously stalled, is about as likely as being hit by lightning 3 times in the same place on the same day, then I don't need that silly little computer.  It's not doing anything useful for me or anyone else onboard.

I want you to try a thought experiment for me.  I want you to design a computer control system that's intended to prevent crashes wherein a complete failure of the computer itself or its sensor input doesn't result in the very problem that it was intended to prevent.  Let's try something simple like a stall.

I want you to design a computer program that prevents stalls (to prevent aircraft from crashing into the ground) that doesn't result in crashing into the ground if the airspeed indicator becomes blocked with ice or debris.  The computer program will push the nose down, or in whatever direction it needs to go, to prevent loss of lift from causing the aircraft to fall out of the sky.  If the program responds to the ASI blockage by pushing the nose down (because it thinks airspeed has been lost) when it's blocked by ice or debris, even though the aircraft hasn't stalled, then you fail.  If that hardware or software fails due to loss of power or malfunction (electrical short circuit, for example), then you also fail.  If that seems like an impossible task, there just might be a reason for that.

4. You're offering up a false equivalency.  I said a single engine electric STOL aircraft is inherently simpler and more survivable than a multi-engine electric helicopter.  A drone is an electric helicopter that has no autorotation capabilities unless it's using variable pitch rotors / propellers.  Virtually none of those drones have that feature because it adds additional cost and complexity.  If control avionics or software execution or power is interrupted, reason unimportant, then the drone literally falls out of the sky.  If I cut the power in a STOL aircraft piloted by a half-way competent human, it doesn't drop like a rock.  It glides because it has wings that produce sufficient lift to keep it gliding at 25mph to 35mph.  Most people don't die from 30mph crashes.  Go look up how many people have survived terminal velocity descents into the ground.

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#19 2019-05-04 20:00:40

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,902

Re: Autonomous Passenger Carrying Electric Aircraft

Not sure what the original topic was other than it was energy needed to fly but I think that this fits still...

Europe's First Hydrogen Drone Doubles Flying Times with AMS Cylinders

The extended range was achieved by swapping the original 1.5L cylinder, which weighed around 1kg, for AMS's innovative new 3L carbon composite to two hours, by using a new, ultra-lightweight gas cylinder.

AMS Type 3 carbon composite cylinders offer high pressure (300 Bar), ultra-low weight, and optional NLL (Non-Limited Life) performance.

The e-Drone Zero can now fly 3 to 4 times longer than any Lithium-ion powered electric drones - opening up new possibilities and applications, including surveying, security, search and rescue, defence and mobile mapping.

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#20 2019-06-09 09:38:15

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,902

Re: Autonomous Passenger Carrying Electric Aircraft

Largest Ever Hybrid-Electric Aircraft Takes Flight

Los Angeles-based Ampaire unveiled its prototype electric-powered plane, the Ampaire 337, in a test flight above Camarillo Airport in California on June 6. Never before has a hybrid-electric aircraft this large actually taken off.

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#21 2019-07-07 22:01:45

SpaceNut
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Re: Autonomous Passenger Carrying Electric Aircraft

The hydrogen-powered Scai air taxi could fly five people or 1,000 pounds of cargo up to 400 miles.

Alaka’i Technologies says hydrogen fuel cells will give its six-rotor Scai air taxi greater range and lifting power than competitors using batteries

Most battery-powered air taxi designs only have enough power to carry two passengers for around 15 minutes before needing to be recharged

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#22 2019-07-13 11:01:05

kbd512
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Posts: 3,771

Re: Autonomous Passenger Carrying Electric Aircraft

Eviation's Alice All-Electric Aircraft has a Double-Digit Sales Order for US Commercial Aviation Operations

Eviation’s All-Electric Alice Regional Airliner Secures a Major Launch Order – AINtv

$200 per flight hour!

That's a ridiculously small fraction of a single-engined turboprop, never mind a twin!

8 pax with $50 tickets could cover all operating costs, pilot salaries, and profits!

Expected sale price is $4M US, which is well within the range for these sorts of aircraft ($2M to $12M).  Socata's single-engine TBM 850 is around $4M US per copy.

Battery requires 1hr 10min to achieve a full charge, so not quite fast enough for major operators but more than fast enough for the types of operators who run these smaller aircraft.  From a maintenance perspective, engine time on-wing should be drastically improved by electric motors and there is very little maintenance for batteries, apart from maritime environments.

Time will tell, but double-digit sales orders usually ensure that something at least gets built and certified by FAA.  The prototype has already been built and flown, so there's that.  It's a tail dragger, but could use asymmetric thrust in cross-wind landings.  Lots of tail draggers are still operated for rough field performance and sky diving.

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#23 2019-11-11 12:23:25

SpaceNut
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Posts: 19,902

Re: Autonomous Passenger Carrying Electric Aircraft

tahanson43206 wrote:

For SpaceNut .... Following Louis' lead, here is a new top level topic devoted to supercapacitors

Supercapacitors are mentioned in several posts in the NewMars archive, but not an overwhelming number, and no topic had anything to do with the subject.

I've been interested in supercapacitors for some time, but the power storage capacity has been so limited, and the cost for that storage has been so high, that I decided to wait to see if anything comes out of research.

In the article at the link below, there is news of a collaboration between MIT and Lamborghini to outdo Lithium Batteries.

This is one of many similar reports:
https://www.greencarreports.com/news/11 … l-car-ever

My takeaway from scanning several articles is that progress HAS been made, but the total amount of storage achieved is still a small fraction of what is required for a practical long range electric vehicle.

(th)

tahanson43206 wrote:

For Calliban re #5 ...

Thank you for adding to this topic!

I agree that (from all I have read so far) supercapacitors have a lower power density than batteries, but I'm not sure (at this point) if the difference is by volume or by weight.  Please comment upon this quote from the article:

The Sián's 48-volt e-motor, built into its transmission, uses a supercapacitor as its power reserve. Lamborghini has not provided the exact specifications for its supercapacitor, but it has revealed that it's three times more powerful than a lithium-ion battery of the same weight.

I'm unsure of the meaning of "powerful" in this context.

The comparison of weight is a useful marker.

The implication might be that for an aircraft with volume to spare, a supercapacitor of this new design might be able to store three times as much "power" as a comparable set of lithium batteries, without the risk of fire, or (presumably) the cost of materials.

That last is another point of uncertainty, since the materials used for the new capacitor are not revealed.

An aircraft type with "volume to spare" would be lighter-than-air craft.

I've seen no reports of electric propulsion for lighter-than-air craft, but that certainly doesn't mean folks aren't working on them.

(th)

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#24 2019-11-11 12:25:47

SpaceNut
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Posts: 19,902

Re: Autonomous Passenger Carrying Electric Aircraft

tahanson43206 wrote:

For Calliban re topic ...

Thanks (again) for moving this topic ...

I wonder if you could try again?  For some reason I'm not picking up on your argument.

My question regarding air ship power was based upon the MIT/auto company claim that they are able to deliver a given amount of power for 1/3 the weight of a comparable lithium battery.  That would suggest that a small airship (runabout size) could be powered by supercapacitors.

Some years ago I read about the early experiments with hydrogen blimps for one person transport by ? Dumas ? in Paris.  A comparable vehicle today would be far superior in many ways, and it would be a nice touch to power the propulsion system with an electric system.

Fuel cells would certainly be an attractive solution, as kbd512 has reminded the forum on several occasions, but I am intrigued by the prospect of "refueling" rapidly and flying for extended distances in the comparative safety of a lighter-than-air vehicle.

Specifically, if the supercapacitor solution weighs LESS than lithium batteries, then the VOLUME of the storage system should not be a problem in a lighter-than-air vehicle, so the number of supercapacitors needed for long range could be incorporated into the design.

Unfortunately, I suspect there is insufficient information available to make an educated guess.

The critical missing piece (may be) the volume of the supercapacitor system compared to the lithium battery solution able to deliver the same power.

(th)

Capacitors are a set of plates seperated by a dielectric that allow the charge to be stored. The plate sizes effect the amount of storeage or capacitance value.
When the capacitors are connected in parellel the values of the capacitor add up such that you are storing more energy.

tahanson43206 wrote:

For SpaceNut re #13

Thank you for the reminder of the nature of traditional capacitors.  I felt the need to try to understand (at little bit better at least) the difference between traditional capacitors and "supercapacitors".

There is a WikiPedia article which seems to be tackling the problem of explaining the difference:
https://en.wikipedia.org/wiki/Supercapacitor

Forum readers are invited to take a look at the section of the article which compares ordinary capacitors (as described by SpaceNut) and supercapacitors.

An interesting feature of supercapacitors, which I do not yet understand, is "double capacitance".

(th)

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#25 2019-11-11 12:27:50

SpaceNut
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Registered: 2004-07-22
Posts: 19,902

Re: Autonomous Passenger Carrying Electric Aircraft

tahanson43206 wrote:

A potential driver of supercapacitor research is market demand.

NASA has been working on an electric airplane since 2015, according to the article at the link below.

https://www.yahoo.com/news/nasa-unveils … 07127.html

Due to current battery limitations, the Maxwell's design is envisioned for use in short-haul flights as an air-taxi or commuter plane for a small number of passengers. (Additional reporting and writing Steve Gorman in Culver City, Calif.; Editing by Sandra Maler)

I'm intrigued that the NASA team (apparently) decided NOT to pursue fuel cell technology.  Perhaps at the time planning was underway to establish the scope of the project, fuel cell (and fuel supply) technology was not thought to be far enough along.

It seems (to me at least) likely that the ubiquitous availability of utility scale electric power may have swung the balance toward lithium batteries.

It will be a while (if ever) before Hydrogen (or even Ammonia) becomes available at a comparable level.

(th)

The mass of tanks is considereable when compared to the supercapacitor which has electrolyte with simulate to fuel cell membrane materials making it sort of a hybrid depending on construction to being a battery as well. The making of supercaps in multiple plate wraps with different materials between them allow for the change in how they function for power delivery.
One of the first version of supercaps were made for use as a memory keep alive circuit power source for critical data when power failures occur where the demand if micro current level.

tahanson43206 wrote:

The announcement of successful research at the link below should be of interest to those in the forum who are supporting the idea of using aerogel for various applications.  By using aerogel the researchers have (apparently) greatly increased the capacitance of a new design for a supercapacitor.

The link also reports on the use of carbon nanofilm in the fabrication of the material incorporated into the material.

https://phys.org/news/2017-07-team-fast … citor.html

(th)

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