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Apparently, the weight of the turbine without the gearbox or hydraulics-related accessories truly is 88 pounds. The solar T-62 APU with nearly identical output weighs in at 142 pounds, so the I-APU turbine is much heavier than I estimated but much lighter than a similar output kerosene burner.
The nominal fuel burn rate is 3 pounds per minute and it runs at 100% for pretty much the entire time, so 135hp output, except during startup and shutdown or anomalies that require increased power output from a single system. That makes the fuel burn 180 pounds per hour, and nominal fuel burn rate is 1.33lbs/shp/hr. That's right inline with the T-62. Hydrazine as a monopropellant has far less energy than RP-1 (1.6MJ/kg vs 43.4MJ/kg), so the fuel burn rate seems suspect to me.
Does the greatly increased density of the exhaust product combined with nearly identical operating temperatures as a PT-6A somehow produce the same amount of driving force / torque as Jet-A and air does in a T-62, resulting in a fuel burn rate only slightly worse than a similarly small / fast-turning Jet-A burner? Surely not. Something must be wrong here. The SRB APU fuel quantity seems to agree, though. If this is so, then doubling the gas temperature and throwing a 50% heavier exhaust product should lower the fuel burn rate considerably, somehow making our storable monopropellant at least as good as Jet-A, at least for a very small turbine. I dunno. It seems wrong.
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Louis,
We're definitely going to need more "wing" to allow for Cessna 182-like speeds, yet somewhat shorter biplane wings, a small tank of fuel, a large slow-turning prop, and maybe this could actually work without invoking any wondrous new technologies.
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I think we need to spend the money to qualify CNT and aerogel foam as structural materials for the propeller and as a sidewall reinforcement for the tires in lieu of the Kevlar used in the Airframes Alaska "Bushwheels". Keeping the MMOI on the prop as low as possible will do wonders for the longevity of our Mars-rated club. The rest of the airframe can be constructed from less expensive high-modulus CFRP and Nomex honeycomb core. The airframe and the tires of the Perlan II glider are already subjected to Mars operating temperatures on every flight. We also need to determine what kind of damage the dust will do to the prop, canopy, leading edges, and pitot tubes. Maintaining laminar flow and not killing the pitot tube readings from dust ingestion is very important. The wings and empennage of Perlan II are already removable for transport. We need to repurpose the avionics from Orion and write some new software based upon the work of the Ingenuity team. Some minor amount of wing sweep will assure that we don't accidentally rip the wings off by going supersonic in a dive or a bank near the operating altitude limit.
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I will take a detailed look at the monopropellant engine discussion later today. I am not ignoring it, just snowed under with work.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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The problem of designing an aircraft for low altitudes and (practical) low takeoff and landing speeds on Mars is essentially the same as designing an airplane that fly at those speeds at about 105-110 thousand feet on Earth. At takeoff or landing, you will be operating near (but not at) stall lift coefficient. Your lift coefficient will be near 1.
Lift must balance weight, which on Mars is fortunately less. L = W = q CL S, where q is the dynamic pressure and S is the wing planform area. Thus the design wing loading for takeoff and landing is W/S = CL q ~ q. The dynamic pressure is q = 0.5 rho V^2 = 0.5 sp.ht.ratio P M^2, where rho is density P is static pressure, and sp.ht.ratio is the specific heat ratio of the atmospheric gases (1.4 on Earth, 1.33 on Mars.
Your problem is that q on Mars at any practical speed is a very low number, since surface density there is 0.7% that of here. Weight is 38% that of here, so the density effect is far, far larger. Thus exceedingly low values of wing loading are required, leading to extreme fragility of the airframe structure. Or infeasibility. Depends on the speed you use.
For 60 mph takeoff and landing speeds, a sea level q here is 9.2 lb/ft^2, while on Mars it is 0.064 lb/ft^2. Thus the wing loading of a light airplane here is in the 9-10 lb/ft^2 class, while on Mars it is in the 0.06-0.07 lb/ft^2 class. Even allowing for the reduced gravity on Mars, a kite is too heavy a construction to fly in a 60 mph wind on Mars.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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GW,
You're right. In my zeal for this concept, I hadn't noticed that I didn't do another silly unit conversion. You have to have at least double the wing area of Perlan II, use the 0.479 Cl value from NASA's PSU94-97 airfoil, and be moving at 120m/s (Mars local 0.5 Mach) to produce enough lift force to takeoff. If a human pilot is behind the controls, that's never going to work. Even if you invoke advanced materials to cut the airframe weight in half, the takeoff speed still isn't reasonable.
Argh! What is wrong with this place and its stupidly low value for rho? Seriously, who designs a planetary atmosphere that way?
Well... At least you can fly a decent plane in the atmosphere of Venus. You won't be landing anywhere, but at least gliding shouldn't be too much of an issue.
I wouldn't trust a helicopter here, either. You'd "auto-rotate" about as well as a brick does.
And... Another idea bites the dust.
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Kbd512:
I'm pretty sure an airplane can be designed for Mars, it just won't be able to take off and land the way airplanes do here. It can only fly at higher speeds, just like craft flying subsonically at 105 thousand feet here on Earth. Sort of like the U-2 design problem, just worse, because it's thinner yet.
My first guess would be a rocket-powered tail-sitter that thrusts off the surface and pulls over into high enough speed to fly at a buildable wing loading (1+ psf, preferably 5+). To land it pulls up into a tail-slide, and lands retro-propulsively with its rockets. Cruise propulsion is whatever we think we can get to work there, but it's a whale of a lot less thrust than for VTOL.
My second guess would be to blend the supersonic rotor technology that Ingenuity has, with an airplane, for takeoff and landing (wings plus rotors). The downside would be the danger of the rotor shockwaves to nearby personnel, plus the noise, which would be enormous, even in that thin air.
Not that rockets aren't noisy, because they are. But shocks shed outside the plume aren't usually involved. That sudden shock wave pressure-rise can be quite dangerous.
GW
Last edited by GW Johnson (2021-04-20 12:31:00)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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GW,
I still think this idea has real merit on Venus, mostly because it doesn't require any new materials or drastic airframe changes, but I just don't see conventional aircraft or helicopters large enough to carry humans working very well on Mars, given how fast you have to fly to stay above stall speed. This was my fault. In my zeal for some kind of usable aircraft, I wasn't careful in converting my units, and was engaging in a little bit of magical thinking. I should've known better. If it looks too good to be true, then you messed up the math somewhere along the line.
It's not completely hopeless, but the aircraft basically has to takeoff with the assistance of a rocket or catapult and land with the assistance of a rocket. There's no such thing as the ability to "takeoff from wherever" and "land wherever". At that point, you may as well use a rocket. The dust makes routine extended duration flights at high subsonic or supersonic speeds a bad idea for airframe longevity. Any fan, propeller, rotor blade, canopy, or other leading edge surface that gets pelted with volcanic ash at high subsonic speeds is destined for the scrap heap.
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GW, would an Ekranoplan ground effect vehicle work on Mars? This seems to be a good way of boosting lift, albeit close to the ground.
Vorticity would no doubt stir up a great deal of dust, but if the vehicle is travelling fast enough, the pressure cone it creates should prevent this from impacting the wings or fuselage. What are your thoughts?
Last edited by Calliban (2021-04-20 14:23:47)
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Maybe a Mars helicopter could make use of ram jets mounted on the rotor tips? The centrifugal forces on the rotor tips would be huge.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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The density of the Martian atmosphere at 'sea level' = 0.013kg/m3, y = 1.3. The density of Earth atmosphere at 10km = 0.43kg/m3, y = 1.4. Lift per unit wing area compared to Earth = (1.3 x 0.013 / 1.4 x 0.43) = 0.028. Given that lift is proportional to the square of velocity, a 747 flying on Mars close to the ground, would need to fly 6x faster to generate the same lift, or 3300mph. This is 1.5km/s.
How much faster would the plane need to be travelling to fly to other side of the planet on a sub orbital trajectory? Low orbital velocity is 4km/s. So somewhat less than that. And for most of its journey a sub-orbital vehicle would be outside of the Martian atmosphere where drag would be zero. It would not need wings, thereby saving a great deal of mass. As a ballistic vehicle, it would not need a runway. The CO2 atmosphere of Mars is not really a promising oxidant for combustion engines. The few fuels that do react with CO2 produce particulates that would obliterate a gas turbine in seconds. Hence, discussion has shifted to mono-propellants as fuel-oxidiser combinations.
So the atmosphere is useless as a source of in-flight propellant and the effective wing area needed at sub-sonic speeds diminishes payload fraction to effectively zero. Whether it is possible or not, an aeroplane may not be the most efficient solution for long distance travel on Mars. On Earth, a suborbital trajectory is far more challenging, requiring much greater speed and KE. And the atmosphere provides plenty of lift at much lower speeds and is a useful oxidiser for engines. On Earth, flying across the Atlantic is cheaper than trying to cross it on a sub-orbital trajectory. On Mars, the lower gravity and much thinner and largely inert atmosphere, turns those advantages upside down. It suggest to me that ballistic vehicles may be a more promising line of research. The atmosphere may be useful as propellant in some sort of ram jet engine burning silane, as the craft accelerates to suborbital velocity. But even here, it presents a design complication that may not be worth the modest reduction in propellant mass that it would allow.
Last edited by Calliban (2021-04-21 05:23:54)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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Calliban,
If you increased the speed to Mars local Mach 0.5, cut the weight of Perlan II in half using advanced materials, changed the airfoil to NASA's high-lift PSU94-97 design, and doubled my proposed wing surface area once again, then you have just enough lift to merely take off at Mach 0.5. Apart from increasing Cl using a much higher lift but inherently low-speed airfoil design, there's no other practical way to make a single-seat aircraft fly on Mars. That kind of speed is well above what commercially rated pilots land airplanes at, so the APEX-16 and PSU94-97 airfoils are automatically excluded from designs that would be practical for an airplane carrying a pilot. PSU94-97 was actually designed for the high-speed "Mars Airplane" drone that NASA / JPL was working on some years back, and intended to fly at relatively high altitudes and at high subsonic speeds.
Design and Predictions for a High-Altitude (Low-Reynolds-Number) Aerodynamic Flight Experiment
Is that still technically doable using the airfoil design that they've already done work on?
Barely. The X-15 landed at 242mph. This Mars powered glider would land at 268mph. There's not much practical difference there. The problem is that every X-15 was flown by an incredibly skilled pilot with many years of experience in multiple types, they were landing on a dry lake bed as flat as a pancake, and they STILL had fatal crashes during landing attempts. The wings on the X-15 were stubby little trapezoids intended for hypersonic flight. Perlan II has very long and slender high speed sailplane wings. If you screw up, even a little bit, you'll be cartwheeling across the ground at NHRA drag racing speeds, but without the benefit of a tubular steel cage and head restraint to protect you.
To land at practical airliner speeds (120mph range), this glider needs at least 48.8m^2 of wing area (double that of Perlan II) and Cl has to be closer to 2.5, as was the case using the Selig S1223 airfoil design. The available CFD codes produced Cl results that disagreed considerably with actual test data obtained from multiple sources, so this is not a well-developed design, although it's been studied at length by numerous university students / professors because it produced so much more lift than other existing designs. It's more of a curiosity here on Earth due to our sea level atmospheric density. Anyway, we're talking about another half billion dollar development program here, with far more complexity involved than what was required to make Ingenuity fly on Mars.
This airfoil design would need to be aeroelastic in nature, meaning reconfigurable for higher cruise speeds using torque tubes to prevent a massive drag rise at higher speeds, but that is another aspect of airfoil design championed by DARPA and flown on real military and civil aircraft. It would essentially be a Hershey bar design, 2.5m (8.2ft) in width and 9.76m (32ft) in length for a pair of airfoils (48.8m^2 of total airfoil area for both wings). This could be done using BNNT fabric since that is easily bondable to epoxies, whereas CNT is not, and Aerogel foam construction, with a tubular wing spar acting as a torque tube by having bolts of fabric laminated into the leading / trailing edges and wrapped around the spar, such that sections of the spar twist to provide "flaps" and "ailerons". The same would apply to the empennage.
This is an inherently low speed design that will never achieve the same cruise speeds that Perlan II achieved at 75,000ft here on Earth, but it has the necessary advantage of providing takeoff / landing speeds on Mars of around 55m/s (123mph). There will almost certainly be flutter problems at higher speeds, so the flight envelope will be pretty limited.
Can this scale to permit something akin to a "Mars-rated Beaver" design?
I dunno, but it should permit a single suited astronaut to attain flight at practical takeoff / landing speeds.
One thing is very certain, though. A practical airplane can't fly on Mars in a practical way without advanced materials, airfoil designs, aerodynamic control techniques, and a monopropellant that decomposes to produce a very dense high-temperature gas over a strictly life-limited catalyst bed that would be lucky to see 100 hours of service prior to replacement, not refurbishment.
Anyone who thinks supersonic or hypersonic flight is practical, without employing a very tough rocket-propelled vehicle through a mostly exo-atmospheric flight regime is only kidding themselves. See what's happened to aircraft that have flown through volcanic ash at high subsonic speeds here on Earth. Apart from destroying the engines, it also sandblasts every leading edge on the airframe and the canopy. It's the speed that counts here, not atmospheric density.
Edit:
I did not mean to suggest above that this aircraft would have a single pair of wings 32feet long, merely that that was the required surface area. The airframe still needs shorter / stiffer biplane or "X" wings (a pair with slight dihedral and a pair with slight anhedral), similar to Burt Rutan's "Quickie" airframe, in order to keep the weight of the spars manageable. On Mars, someone will easily be able to lift the entire empty airframe, without fuel, over their head using both hands. That's how light this has to be. The turbine wheel and housing need to be RCC with an oxidation-resistant ZrC thermal barrier coating, the gearbox and gears need to be BNNT reinforced PEEK, the oil reservoirs will be fluoropolymer coated PEEK plastic, etc. This is going to be the most expensive "Quickie" style airframe ever created, by far. Controls will be completely manual, landing gear will be fixed, no provision for an autopilot. Heck, the wheels will be BNNT composite and the tires will be CNT reinforced fluoropolymer. The fuel tank needs to be a fuselage structural member. Apart from the catalyst bed, there won't be a single piece of metal in the entire airframe, or power plant, for that matter.
We're going to become disciples of the Burt Rutan School of Aeronautical Engineering:
"Whatever you want to make your airplane out of, throw a piece of the material up into the air. If it comes back down, then it's too heavy."
I think it'll work, but it's gonna cost a pretty penny. The catalyst bed is trash in 50 to 100 hours, and that's not cheap at all. Any type of crash is likely to be fatal. This thing will fold up like a piece of cardboard in a stiff wind if anything but the landing gear hits the ground. It's basically a disposable flying beer cooler with a flexible fabric skin thinner than paper, but it's even lighter than a styrofoam beer cooler. The empty weight to useful load ratio will be something worth writing home about.
Edit 2:
* The world's most expensive flying disposable beer cooler.
* The world's most expensive ceramic 135hp gas turbine engine for a power-to-weight ratio like no other.
* The world's most expensive landing gear.
Edit 3:
If we can make a gas turbine powered "Mars Trophy Truck" that can perform like the Earth-bound trophy trucks do in Baja, then maybe we could use a CNT tow ribbon to help get this lumbering beer cooler up to flying speed.
Last edited by kbd512 (2021-04-21 12:58:34)
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Kbd,
The catalyst would be vulnerable to high temperature oxidation as your HAN fuel breaks down producing oxygen ions. A nickel catalyst would be the cheapest effective combustion catalyst. Often catalytic metals are produced as coatings on an oxide substrate to give the highest effective surface area. One option to consider would be to have catalyst cartridges, consisting of nickel coated aluminium oxide particles, say, in a stainless steel shell. After each flight, or every 2-3 flights, the cartridge is replaced with a fresh one. Nickel is a relatively cheap metal. A noble metal catalyst would be longer lasting but more expensive to begin with.
I still think it would be a good idea to make use of fuels that react exothermicaly with Martian atmospheric CO2. That way, you get a higher effective specific impulse by only carrying fuel and not oxidiser. Probably the way to do this would be to burn a bipropellant in a jet engine that compresses atmospheric CO2 as a buffer gas. We would then burn silane in an afterburner, after the turbine. The very low pressure of the Martian atmosphere means that expansion ratio would still be good. Close to 100% of the work output of the turbine would drive the compressor. It's purpose would be to provide a dense CO2 stream for the silane to react with.
I can't really comment on the airframe. Your analysis sounds good.
Last edited by Calliban (2021-04-21 15:08:33)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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This idea of Kbd512, looks better the more I read into it.
https://en.m.wikipedia.org/wiki/Trophy_truck
Assuming that we know where we are going to land and where the sites of scientific interest are, we could land small propellant plants weighing maybe 1te each at strategic locations. These would use solar power or 1kwe Kilopower units to produce propellant for vehicles.
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Calliban,
The problem with the catalyst bed is not so much the life of the catalyst, it's the fact that you must unbolt the engine from the airframe and disassemble the turbine casing to remove it, because it's located inside the casing, in order to expand hot gas through the expansion turbine. The last time we did tear-downs of jet engines at the 50 to 100 hour mark here on Earth, all such engines were operated by the military, because only they could afford those kinds of maintenance schedules. That's why we still had piston engines in airliners into the 1960s, and much later in other parts of the world. As operational experience was accumulated and better manufacturing techniques became available, which happened quite fast, we arrived at where we are today with turbofan engines that have 50,000+ hour "on-wing" times, with some as high as 150,000 hours.
The way I read your Post #38, you want to put a bunch of heavy equipment in my ultra-lightweight beer cooler. For a supersonic airliner, I can understand the appeal of an after-burning turbofan engine. Much higher operating speeds are nearly a hard requirement for that kind of aircraft. Once again, I must stress that speed is both an ally and an enemy. You can't fly through a cloud of iron oxide or volcanic ash at high subsonic speeds, never mind supersonic speeds. You need enough speed to keep the wing flying, but not so much that airframe leading edges look like they've been belt-sanded. Here on Earth, flying through airborne particulate clouds messes up Aluminum and composite airframes something fierce and completely trashes the fan blades and casings or cylinder bores and pistons of the engines involved. We run our M1's AGT-1500s until they're so chewed up that they quit running. You will not do that with an aircraft engine. Ever.
Combusting Silane produces molten Silicon-Dioxide and Carbon, so that mandates an open combustion chamber design. If you have an open chamber combustion engine, then it may as well be a rocket engine. The thrust is fantastic, the engine is lightweight, and using pure thrust for propulsion means you can have airframe structures made from good ole fashioned steel. However, supersonic or hypersonic flights will be mostly exoatmospheric in nature, following parabolic trajectories from Point A to Point B, using thrust to slow the rate of descent back through the dust cloud.
Regarding Trophy Trucks:
First Drive: Ken Block Drives the ALL NEW Extreme E Electric Racecar in Last Stage of Dakar Rally
Ken's obviously a very good driver, but he's not familiar with the course. He finished 3rd overall in the last stage of the Dakar Rally using an all-electric trophy truck, despite getting lost at one point. The winner's time was 8:50. Ken's time was 9:17. The day before the race, he was out Hooning on the thing. The most notable thing he said was, "when you get on it, there's no turbo lag or waiting for the engine to spool up to make power." This is clearly what we want on Mars, especially for an aircraft tow vehicle. It will need proper mud guards / dust flaps, though. Please take note of the giant dust clouds he created. This is exactly what it would look like on Mars, only to the nth degree. The pilot will have his or her hands full with the plane while the tow vehicle is paying attention to the terrain it's dragging the aircraft over. A mechanical release bridle will untether the aircraft from the tow vehicle after flying speed is achieved. Over smooth ground, 120mph is easily attainable for an electric off-road truck.
Regarding the power provisioning, I would say base resources produce the propellants, the electric trucks will contain fuel transfer tanks and pumps to fuel / de-fuel aircraft. The monopropellant is an easy-to-handle liquid that remains liquid at very low temperatures, is very difficult to ignite without a lot of heat and a catalyst bed, and far less toxic than Hydrazine, making it quite suitable for use on Mars. Even so, there will be no over-flights of pressurized structures, nuclear reactors, or solar panel fields.
Everywhere you fly, there must be rules. A nuclear reactor or solar array field is Class Papa (Prohibited) airspace, all the way to the edge of space, never to be overflown by any crewed vehicle. Airspace with pressurized structures below will be Class Papa up to 2,500ft above MSL. Airfields will follow similar airspace restrictions as here on Earth, with allowances made for the differences in aircraft performance. Everything else is Class G airspace, unless certain routes are regularly flown, and then there will be flight levels for passenger services. If you bust class Papa, the equivalent of a Mars FAA / civil aviation authority will review the circumstances and then determine whether or not your pilot's certificate (license, but without the need for court orders) is revoked. The same process will apply to any pilot who fails to follow ATC instructions, such as crossing an active runway without approval to do so. Drone operators will also be subject to FAA flight rules.
Every private pilot will learn to fly a single-engined, fixed-gear, land or rotary wing plane with a turbine engine first. There are obviously no bodies of water on Mars, so no need for ratings associated with float-equipped planes. There will be ratings / logbook endorsements for complex aircraft (variable pitch prop and/or retractable gear), high performance aircraft, instrument flight qualification for IMC flight into dust clouds, multi-engine rating, and individual type ratings for large / complex aircraft such as airliners and rocket-powered vehicles. To fly for hire, you need to be a commercial pilot at a minimum (possibly still governed under Part 91 operations). To fly paying passengers as part of a commercial airliner service (Part 121/ 125 / 135 operations), you need an ATP (Airline Transport Pilot) rating, someone who is typically a CFI (Certified Flight Instructor) with a minimum of 1,500 hours of flying experience. All of this will come in due time, but the rules must accompany flight operations to maintain the trust with the general public.
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Perlan 2: High aspect ratio wings, which does make sense in terms of maximising L/D. Reading about that, one of the most significant limitations on aspect ratio is the dimensions of ground facilities. On Mars, aircraft facilities will need to be specifically designed for extremely long wing spans. It would make sense lifting planes onto trailers and taking them into facilities sideways. The sheds would need to be pressurised to allow work on the planes without a spacesuit. As there is no significant wind loading on Mars, the cheapest option would be a basalt fibre reinforced polymer inflatable, with a cross-linked steel hoop frame beneath it to prevent it from collapsing when pressure is released. The door would need to be hinged, opening outward, with a rubber compression seal. If we can afford the facilities and the runway, then it solves one of the problems with high aspect ratio aircraft.
The fuselage is a double ellipse, which is the most aerodynamic non-lifting body shape Cd ~0.02. When hydrogen filled rigid airships were finally subjected to aerodynamic optimisation in the 1930s, the double ellipse was identified as the most fuel efficient shape. It was too little too late for the rigid airship.
The only way I can see reducing drag further is to have a tapered flying wing design. The engine nacelles need to be internal to the wing structure, to avoid adding drag to the design. The wings themselves will need to carry the fuel tanks. So basically, the aeroplane needs to be a very high aspect ratio flying wing, which tapers wider in the middle.
The runway length must be very long, as the plane needs to reach ~Mach 0.5 (260mph) on Mars to takeoff. The problem with trying to use some sort of assisted takeoff is that any point loadings on such a slender airframe would probably result in buckling of the airframe. Thrust, weight and lift would ideally be distributed evenly across the lifting wing, to avoid bending during flight.
Could we build airliners on Mars, with a long, thin, perpendicular cabin with single row seating that is actually built into the high aspect ratio wing?
For aeroplanes to work on Mars, we need a low cost method for producing long runways. Does anyone have any ideas about that? Under discussions for Mars landing pad, Tom suggested using thermite to produce a hard glassy surface. Maybe something similar could be made to work here. Small amounts of aluminium or carbon mixed with iron oxide rich fines, compressed and then heated to 1000°C using a radiant resistance heater. The iron oxide would partially reduce, forming long polymer-like chains. This is how foundation bricks are made. The resulting brick is extremely strong and impermeable. A similar process could produce hard, flat runways once large rocks are removed and the soft fines are rolled flat.
One thing that I did notice when I modelled there Martian atmosphere was that atmospheric density declines rapidly with height. This is because almost the entirety of the Martian atmosphere is CO2, which has high molar mass and is very cold. So the aeroplane should fly low, preferably no more than 1000'. The problem with flying low on Earth over land, is that updrafts are severe. On Mars, because CO2 is present beneath its critical point, changing temperature may result in significant changes in local density and viscosity. This effects Reynolds number and lift.
Last edited by Calliban (2021-04-22 17:27:46)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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It looks like the industry will change, several representative methane storage schemes, they looked at Solar and there was a look hydrazine fuels for Mach transport aircraft, variants of hydrazine can be used as rocket fuel.
US Air Force partners with Electra on ultra-short takeoff aircraft
https://newatlas.com/aircraft/agility-p … ltra-stol/
GM Co-Developing Hydrogen Fuel-Cell for Aircraft
https://www.americanmachinist.com/news/ … s-liebherr
EU green jet fuel mandate will carve out market for big players, industry warns
https://biofuels-news.com/news/eu-green … try-warns/
Flight of the Prandtl: NASA's Mars Airplane Prototype
https://www.space.com/33906-nasa-mars-a … hotos.html
NASA Mini-Sniffer, a Mars concept airplane designed in the 1970s, also ran on hydrazine.
https://www.wired.co.uk/article/nasa-vi … aceshuttle
"Mini-Sniffer III" was a new build aircraft, similar to Mini-Sniffer II but with a longer fuselage and the hydrazine engine. It was designed to carry an 11.3 kilogram (25 pound) payload to 70,000 feet or higher. However, the Mini-Sniffer III only made a single flight to 6,100 meters (20,000 feet), and was not flown again because fuel leaks made it hazardous to handle.
. A normal internal combustion engine burns gasoline with air to generate power, but at 21 kilometers the air is too thin to keep it running. Instead of gasoline, Reed planned to use hydrazine, or (NH2)2, which breaks down spontaneously when run across a catalyst, generating heat to produce steam to drive the engine. Hydrazine is a corrosive, toxic, and unstable propellant, but its ability to "burn" without oxygen makes it useful for spacecraft thrusters and for such high-altitude engine applications.
ARES would have traveled to Mars compactly folded into a protective aeroshell; upon entry in the thin atmosphere, the capsule would have deployed a parachute to decelerate, followed by ARES release at altitude.
As well as the aforementioned goals, the aircraft would also have investigated the atmosphere of Mars and its weak magnetic field
https://web.archive.org/web/20100329224 … ility.html
The Sky-Sailor is a concept for a robotic aircraft with embedded solar cells on its wings, conceived in 2004 by the Swiss Federal Institute of Technology in Zurich. It is hoped it would be able to study the Martian surface
https://www.newscientist.com/article/mg … n-on-mars/
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How NASA will use helicopters to return samples from Mars in 2033
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This NASA design is being developed in partnership with Boeing.
https://www.nextbigfuture.com/2023/06/3 … plane.html
It could reduce fuel consumption by 30%. This is a very significant development if it can be commercialised.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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Calliban,
The drag clean-up associated with using tandem high aspect ratio wings that don't store fuel, combined with a thrust-vectoring prop-fan in the tail, would do as much or more to improve fuel efficiency as strut-braced wings. AGA-33 was intended to provide a rough 1/3rd fuel consumption reduction using a modestly swept conventional high-aspect wing with a V-tail and slightly reduced cruising speed. Otto Aviation's Celera 500L flies at the same cruise speed as the twin turbofan powered AGA-33, but is even more fuel efficient, but has no wing sweep as far as I can tell. Add Caterpillar's new diesel piston tech to the Celera 500L, which achieves a 20% fuel consumption reduction on its own, into an aircraft that already burns drastically less fuel than turbofans, and we're talking about fuel consumption similar to a commuter car, except that it's cruising at or near the top speeds of WWII propeller driven fighters while doing that. We must use more powerful turbofans for larger aircraft, but diesel powered light aircraft could easily make a run at conventional airliners and come out on top on cost grounds, especially when it comes to fuel burn rates. At 30mpg, you only need 67 gallons plus 45 minute reserve to fly 2,000 miles, so $61.11 in fuel costs per passenger in the 6 seat Celera 500L, at $5.50 per gallon of Jet-A here in Houston, or $34.87 if the engine burns diesel. It's hard to imagine getting much more efficient than that while flying 2,000 miles at 400mph, using existing technology, but the improved pistons will deliver an additional 20% reduction. We'd need dramatically lighter composites to do much better.
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This is taken from another thread (CH3)2C4H2O. Although often abbreviated DMF
Biomass-derived 2,5-dimethylfuran as a promising alternative fuel: An application review on the compression and spark ignition engine
https://www.sciencedirect.com/science/a … 2020309784
DMF has a number of attractions as a biofuel. It has an energy density 40% greater than that of ethanol, making it comparable to gasoline (petrol). It is also chemically stable and, being insoluble in water, does not absorb moisture from the atmosphere. Evaporating dimethylfuran during the production process also requires around one third less energy than the evaporation of ethanol
a wiki link that was shared by Calliban
https://en.m.wikipedia.org/wiki/Energy_density
Also some news
Can we really fuel planes with fat and sugar?
https://www.bbc.co.uk/future/article/20 … -and-sugar
Commercial Airliner Is First to Cross Atlantic with Biofuel Power
https://www.scientificamerican.com/arti … uel-power/
Hydrogen-electric aircraft start-up wins $116m in financing
https://travelweekly.co.uk/news/air/hyd … -financing
Rolls-Royce Skeptical on the Future of Hydrogen Planes
https://oilprice.com/Latest-Energy-News … lanes.html
Cars
What are alternative fuel vehicles?
https://www.autoexpress.co.uk/sustainab … l-vehicles
We explore the types of ‘alternative fuels’ used to power cars including hydrogen fuel cells, LPG, CNG, electricity and others
2019 article
Company To Produce Methane-Powered Airplane Engine
https://www.aero-news.net/index.cfm?do= … D1CE536EA6
Beech Aircraft's Corporation's Boulder Division developed expertise in producing superinsulated virtually leak-proof cryogenic equipment for storing liquid oxygen and hydrogen fuels in NASA's Apollo, Skylab and Space Shuttle programs.
https://repository.exst.jaxa.jp/dspace/ … -is/518191
Boulder Division used this experience in designing a fuel storage tank for liquid methane, a "cryogenic" fuel that must be supercooled to keep it liquid. Beech Aircraft is producing a four-place lightplane powered by liquid methane (LM) which is stored in two of these specially designed cryogenic storage tanks holding 18 gallons each.
PDF
https://ntrs.nasa.gov/api/citations/200 … 091954.pdf
Last edited by Mars_B4_Moon (2023-12-03 18:11:29)
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Ingenuity Won’t Fly Again Because It’s Missing a Rotor Blade
https://www.universetoday.com/165931/in … tor-blade/
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Japan to support next-generation passenger aircraft development
https://www.reuters.com/business/aerosp … 024-03-27/
co-designed by BMW's designworks, sirius jet's hydrogen VTOL aircraft to take flight in 2025
https://www.designboom.com/technology/s … 1-12-2024/
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