Airplanes on Mars

tahanson43206 · 2019-04-01 19:57:48

for SpaceNut #125

Magnesium strips the oxygen away from the carbon, leaving carbon behind. The text said the engine is being (has been?) redesigned to avoid coating the turbine blades with carbon.

From https://en.m.wikipedia.org/wiki/Composition_of_Mars

Based on these data sources, scientists think that the most abundant chemical elements in the Martian crust, besides silicon and oxygen, are iron, magnesium, aluminum, calcium, and potassium. These elements are major components of the minerals comprising igneous rocks

The exhaust from an engine running on magnesium would (I would think) be on the sooty side. The carbon would exhaust as soot, and magnesium oxide would (presumably) float for some time in the atmosphere as a fine powder.

To my surprise, magnesium oxide is used on Earth for medical purposes:
https://www.rxlist.com/consumer_magnesi … dition.htm

Magnesium oxide is an over-the-counter mineral effective as treatment for

The article also reports that magnesium is needed for normal human health.

(th)

kbd512 · 2019-04-02 20:23:13

SpaceNut,

Thanks for the interesting find. I learned something new today. I'm going to read more about that.

SpaceNut · 2020-06-10 16:19:04

Another good post to add into a topic where it fits...

kbd512 wrote:

tahanson43206,
The primary problem with wings on Mars is that the air density at Mars sea level ranges between the Earth-equivalent of 100,000 to 130,000 feet. Look at the ratio between gravity and atmospheric pressure. The atmospheric pressure and forward velocity will determine the actual lifting force and drag generated as you fly through the air for any given wing design. Sure, Mars' gravitational pull is only 38% of Earth's gravity, but the air pressure at Mars sea level is 11.5 millibars vs Earth's 1,013 millibars. Are you going to be flying or stalling and falling from any greater altitude? That's like 1/88th of Earth's atmospheric pressure, which you only get at Mars sea level, so your wings are going to be truly huge (and therefore heavy) or you're going to be flying really fast when you land. No airliner wings would generate sufficient lift at subsonic speeds to keep the generated lifting force at or above the mass of the airliner at the atmospheric pressure at Mars sea level. So, you either have to have an enormous wing that must be incredibly light and stiff or you have to have quite a bit of velocity to stay airborne at any altitude while staying subsonic, or some combination of both. Mach 1 on Mars is also significantly lower velocity than on Earth.
The U2 was basically a jet-powered glider, but at 70,000+ feet, even with its enormous wings, it was basically 11 mph away from either exceeding the wing's structural integrity and ripping the wings off or stalling / diving / then ripping the wings off. Modern carbon fiber composites are much better than Aluminum when strength / stiffness / mass per unit area of wing are considered, but still not good enough. The Airbus Perlan II glider can actually do what you're talking about, meaning stay aloft at altitudes above 100,000 feet. Perlan II has a pressurized cockpit with just enough room for 2 pilots wearing flight suits. That glider's Vne is 434 mph and I think it can stay aloft at a bit more than half that speed at 100,000 feet. Landing something that delicate faster than the Space Shuttle would be VERY interesting. If it was made from CNT and BNNT, then perhaps it could land at normal airliner landing speeds.
If you break Mach, you'll probably rip the wings off the glider, so the numbers shown in the link below are not mere suggestions for any prospective Mars glider designers:
Speed of Sound on Mars
Airbus paid for the Perlan Project, but Windward Performance fabricated the machine for them:
Windward Performance Perlan II
Perlan II has an 84 foot wingspan and weighs 1,800 pounds. If it was made from CNT and BNNT, it could weigh less than half of that and most likely land about as fast as an airliner does, at Mars sea level. I'd love to see how that thing is packaged behind a heat shield of some kind. Your guess about how well that would work is as good as mine, but the wings would likely have to fold. Still, it would be cool to actually "fly" rather than "fall" to the surface of Mars. I think airliners are pretty much out of the question, though. Airships are doable, but also huge for the payload lifted.

SpaceNut · 2021-04-27 20:19:31

NASA is hoping to one day fly a plane or glider on Mars amid the ongoing success of the Ingenuity helicopter. BB1g6lHa.img?h=533&w=799&m=6&q=60&o=f&l=f

Meanwhile, the glider concept referred to by Berger is known as the Prandtl-M aircraft, or Preliminary Research Aerodynamic Design to Land on Mars.
NASA provided an update into the research of the Mars plane in June 2020, when Version 6.0 was built out of resin, fiberglass and carbon fiber. It was the second of three vehicles to be researched.
The glider, which had a wingspan of 13 inches, was dropped from a larger model plane from a height of more than 300 feet. Eventually all three models will be dropped from a weather balloon at a height of around 100,000 feet to simulate how they perform in the thin atmosphere of Mars.

Mars_B4_Moon · 2021-11-30 05:06:40

Dramatic Video of Mars Helicopter’s Challenging Flight Captured by NASA’s Perseverance Rover
https://scitechdaily.com/dramatic-video … nce-rover/

NASA’s Mars Helicopter Could Revolutionize Off-Planet Exploration
https://futurism.com/nasa-mars-helicopter

Mars_B4_Moon · 2021-12-10 07:27:19

A New Hydrogen Plane Can Fly Halfway Around the World Without Refueling

https://interestingengineering.com/the- … -emissions

NASA’s Mars Helicopter Ingenuity Still in Action

https://www.voanews.com/a/nasa-s-mars-h … 18907.html

New system will use drones to clean hard-to-reach solar panels

https://newatlas.com/drones/drone-solar-panel-cleaning/

kbd512 · 2021-12-12 15:12:16

Mars_B4_Moon,

A New Computer Model With Zero Actual Hardware Development Can Theoretically fly Halfway Around the World Without Refueling

That's exactly how the title of that article should read.

Whenever the very first prototype has completed its maiden flight, then it's an airplane, but not a moment before then. Whether or not it will ever be practical to operate remains to be seen. There are already high temperature solid oxide electrolysis fuel cells that run on kerosene and generate 3kW/kg to 5kW/kg that are more practical to operate, because they use existing Jet-A fuel and all the infrastructure built to supply kerosene.

At 5kW/kg, a 50MWe fuel cell would weigh 10,000kg. The GE-90-115B generates around 110,000shp / 82MW of static thrust (zero forward velocity) and weighs 8,282kg. The newer GE-9X weighs around 9,630kg and develops less thrust but a more efficient burn. You have to add the weight of the electric turbofan engines to the 10t fuel cell weight. The Wright "electric turbofan" is 10kW/kg, so 5,000kg, although 25kW/kg has been demonstrated by several electric aircraft motor manufacturers without superconductors or other nonsense, meaning straight Copper conductor and permanent magnets and Aluminum casings, so 2,000kg for 50MWe. Your fuel economy savings over existing large turbofans is around 25%, because the thermodynamic efficiency of large state-of-the-art turbofans now sits at 50%. The GE-90 generates about 1kWm (mechanical) from 2.5kWt (thermal). The newer but very similar GE-9X is around 50% efficient, or 1kWm from 2kWt.

NASA's 3D Solid Oxide Fuel Cell is 2.5kW/kg and 7.5kW/L, but they have prototypes producing up to 3kW/kg and have indicated that 5kW/kg is feasible using the same tech. More importantly, it's easy and fast to produce to nearly any dimensions and does not require Hydrogen reforming (think sheets of corrugated cardboard laid at 90 degrees, made from high temperature YSZ-laden ceramic metal) and operates at 1,400C (very hot). That puts it 6,666.6L for 50MWe, or 235.43 cubic feet. For comparison purposes, a single aux fuel tank inside Boeing's 747-400ER is 12,151L, and the 747-400ER carries 2 of those, in addition to the fuel in the wings and tail (I think they quit putting fuel in the tail for some reason, though).

By using a kerosene, you don't need thermal insulation over huge fuel tanks and your fuel economy improvement, say 20% after losses are taken into account, eliminates so much fuel mass that your fuel cell and electric turbofan arrangement is probably a wash, meaning the aircraft weighs and therefore performs almost exactly like a modern airliner, but burns 20% less fuel than GE-9X for equivalent performance. On the downside, your aircraft is now carrying a pair of 10t very high temperature fuel cells (combustor can hot), but they're very compact and your fuel consumption reduction means smaller wings and less structural reinforcement are feasible, so less drag.

Long story short, you basically have a wash on weight, but a considerable volume reduction and induced drag reduction. 20% less fuel burn is also a staggering amount of jet fuel- 48 billion gallons vs 60 billion gallons per year. 20% of your fuel in a 747-400ER is 11,400 gallons, so your fuel cell volume is 324% offset. The fuel capacity / volume that you give up by replacing said fuel tank volume with the fuel cell is more than 3X offset, and then you get a 20% fuel efficiency improvement on top of that, so the wings will be smaller, the drag will be a lot less as a result, and that's a virtuous circle in aircraft design. Holding onto such hot fuel cells will require considerable insulation, so I would say that your volume offset is likely nearer to 300% and maybe a bit less than that. Beyond that, you now have a lot of weight in the fuselage that the wings can't support to reduce spanwise bending loads, because putting large / hot fuel cells in the wings is impractical (not enough volume, or too much surface area and therefore heat loss- and those suckers need to remain hot to operate efficiently and cool down slowly after the flight to prevent cracking).

In any event, I think I've shown that this concept is technically feasible without invoking cryogenics, superconductors, or other Unobtanium materials, which drastically reduces fabrication and maintenance costs. Maintenance is a critical aspect of airline services, and by eschewing highly reactive and explosive fuels (as good as that would be to have) / cryogenics / superconductors / other wildly impractical nonsense, we can save at least 20% on fuel per year through simple math, but even more than that after significant reductions in induced drag (drag from generating aerodynamic lift) is taken into consideration. The "whiz-bang" of my take on this concept is strictly limited to high temperature ceramics and insulators, so that no other extreme technology is required. The lightweight / high-output electric motors are increasingly mature technology, and all pilots who have flown behind such power plants indicate that they're as smooth as turbines and utterly reliable. The use of cryogenics and superconductors and LH2 fuel is best left for the generation of airliners following the SOXE / SOFC generation- crawl / walk / run.

Mars_B4_Moon · 2022-06-26 08:52:20

Mars Ingenuity Helicopter Earns its Developers the Collier Trophy
https://www.machinedesign.com/news/arti … ier-trophy

Hydrogen Can Become the New Aviation Fuel, As Mitsubishi and Hokkaido Want To Show
https://www.autoevolution.com/news/hydr … 91718.html

Calliban · 2022-06-26 09:59:19

The Martian atmosphere is so thin that aircraft would need to travel at supersonic speed to generate sufficient lift. Landing at those speeds would be highly dangerous. However, the hyperloop would work better on Mars as vacuum is already available. The track could be made from compressed stabilised dirt and rock with a steel cover.

Mars_B4_Moon · 2022-07-02 15:07:28

Engineers design motorless sailplane for Mars exploration

https://news.arizona.edu/story/engineer … xploration

Mars_B4_Moon · 2023-02-21 04:06:10

NASA’s Mars helicopter aces longest flight in almost a year
https://www.digitaltrends.com/news/nasa … st-a-year/

Lot's talk of Balloons and Spying making the news

and also I think I might bump. Just in case someone finds some interesting articles.

Goodyear vid Wingfoot One blimp
https://www.youtube.com/watch?v=DkH9CEBUrIE

USS Macon (ZRS-5) was a rigid airship built and operated by the United States Navy for scouting and served as a "flying aircraft carrier", designed to carry biplane parasite aircraft, five single-seat Curtiss F9C Sparrowhawk for scouting or two-seat Fleet N2Y-1 for training.
https://archive.fo/avtwD

USS Los Angeles (ZR-3) - German-built as LZ 126, served 1924-39 decommissioned 1932, and dismantled 1940
https://web.archive.org/web/20090207202 … os-angeles

The American Blimp MZ-3A is a blimp owned by the United States Navy from 2006 to 2017. It is a modified American Blimp Corporation A-170 series commercial blimp and given the USN type/model/series (T/M/S) designation MZ-3A and Bureau Number (BuNo) 167811. After delivery to the Navy, the airship began operations as an advanced flying laboratory used to evaluate affordable sensor payloads, the development of new lighter-than-air (LTA) technologies and general flight support for other related research and development/science and technology (R&D/S&T) projects. It was the last airship to be operated by the U. S. military.
https://web.archive.org/web/20070419124 … id=4861240

Mars_B4_Moon · 2023-03-17 14:11:51

Perseverance Watches Carefully as Ingenuity Lifts Off for its 47th Flight

https://www.universetoday.com/160585/pe … th-flight/

Mars_B4_Moon · 2023-05-27 08:55:28

Lego’s Mars Rover Perseverance Is Ready to Explore Your Messy Desk
https://www.gizmodo.com.au/2023/05/lego … essy-desk/

Mars helicopter and Rover will get ist Lego or 'Legoklods' first made by a Danish carpenter, Danish constructed toys "leg godt" translated to English means "play well" the name also means in Latin either "I collect" or "I compose". Theer was also Megablocks, owned by Mega Brands Inc and Ritvik Holdings, a Canadian children's toy company that is currently a wholly owned subsidiary of Mattel, 28% share of Ritvik was sold to the Blackstone Group, Best-Lock Construction Toys an English British brand of plastic building bricks that are compatible with Lego, there is also Meccano is a brand of model construction system, and the American company K'Nex a construction toy system introduced in 1992 although these other companies see to have their own unique sets and to not seem to be in direct competition with 'Lego'. There is a 'Lego' for almost anything, a line of plastic style kids block construction toys, interlocking plastic bricks, an array of gears, sometimes famous figurines or 'robots' called minifigures that are manufactured by 'The Lego Group'.

So I searched if this was their first NASA Mars Airplane. Not the first time they made these toys, a 40 min long video. There is a lot of Lego stuff with NASA sets

https://www.youtube.com/watch?v=Pg5zFl_FUVI

NASA's Perseverance Mars rover captures images of what may have been a wild river

https://www.foxnews.com/science/nasa-pe … been-river

Last edited by Mars_B4_Moon (2023-05-27 11:29:20)

Mars_B4_Moon · 2023-10-02 06:16:14

The curious case of the Mars helicopter that won’t give up

https://www.telegraph.co.uk/world-news/ … urce=email

David Berger, STEM Engagement Embed to Aeronautics at NASA confirmed it is possible to fly a plane on Mars

Preliminary Research AerodyNamic Design

https://flightopportunities.ndc.nasa.go … ogies/151/

NASA's Langley Research Center proposed a Mars Flyer Concept in 2017 that did have both wings and rotors
https://www.youtube.com/watch?v=9xjHCHR5_50

Last edited by Mars_B4_Moon (2023-10-02 06:17:23)

Mars_B4_Moon · 2023-10-02 08:44:52

Ingenuity flight 59 video - Mars Guy channel

https://www.youtube.com/watch?v=GIABf416dBQ

in our old new mars discussion threads we sometimes had so many debbie downers and negative Nancy and Pessimistic who said nothing would fly yet alone a Helicopter

and yet we now still insist nothing will fly or the air is too thin for any type of Aircraft or Balloon?

Back on Planet Earth?

Army turns to high-altitude balloons for more eyes in the skies

https://www.stripes.com/branches/army/2 … 13633.html

USAF makes first U-2 flight with avionics upgrade

https://www.flightglobal.com/fixed-wing … 12.article

and the Chinese type 'Balloon' device jet fighters were being sent up to shoot down, months later, General Mark Milley, head of the Joint Chiefs of Staff, informs "CBS News Sunday Morning" that the balloon was not spying.

Chinese ‘spy balloon’ wasn’t spying – US military chief

https://newsrescue.com/chinese-spy-ball … ary-chief/

A German immigrant in the USA record for the highest unmanned balloon reaching 51.8 km 170,000 ft above Chico, California, the feat has been broken by JAXA Japanese teams.

Although these two men are long gone, they are recognized as the pioneers in the development of the plastic materials which enabled the development of envelopes for stratospheric balloons.

German-American aeronautics engineer who made significant advances the Skyhook balloons were high-altitude balloons developed by Otto C. Winzen and General Mills. The Soviet Osoaviakhim-1 was a record-setting, hydrogen-filled Soviet high-altitude balloon designed to seat a crew of three and perform scientific studies of the Earth's stratosphere. The Soviet crash also provided motivation to develop pressure suits for high-altitude flight; the first operational suits were designed by Evgeniy Chertovsky.
Aeronautics: Balloon Luck
1933
https://web.archive.org/web/20101122151 … 56,00.html

The huge bag rose groggily about 10 ft. It wobbled sideways across the airdrome, but not an inch higher would it go. The ground crew dragged the bag back; part of the heavy apparatus was unloaded. Still no luck. After two hours of struggle, Air Com-mander Garankidze wearily ordered: "De- flate." The ripcord was yanked and the silvery bag billowed to earth. C. A German racing balloon, blown by a stiff wind clear out of Germany and across the North Sea, landed on the English coast. Its crew of three suffered first a ducking, then the embarrassment of being arrested for trespassing on the scene of British secret naval practice.

Another crash and he three Soviet crew members, probably incapacitated by high g-forces in a rapidly rotating gondola, failed to bail out and were killed by the high-speed ground impact. Project Manhigh was a pre-Space Age military project that took men in AirForce balloons to the middle layers of the stratosphere, Skyhook balloons may have been the origin of some UFO UAP observations.

Super-pressure Balloon-borne Imaging Telescope (SuperBIT) a stabilized high-resolution telescope that operates in the stratosphere it carries SuperBIT (at 3500 lbs) to a suborbital environment above 99.2% of the Earth's atmosphere in order to obtain space-quality imaging. In March 2015, NASA launched a SPB to an altitude of 110,000 feet (34,000 m) for 32 days from New Zealand and landed it in Australia after a leak was detected, it was flown for a long duration through the day and night cycle and it was the size of a football stadium.
https://www.theregister.co.uk/2015/04/2 … es_locals/
The SPB TRAVALB-2 surpassed previous Antarctic balloon flights by staying aloft for 149 Days, 3 hours, and 58 minutes after launch from the NASA Long Duration Balloon (LDB) site at LDB Camp, McMurdo Station, Antarctica. The operation was supported by National Science Foundation and United States Antarctic Program.
https://www.csbf.nasa.gov/antarctica/payloads.htm

Some older videos

Lockheed F-104A Starfighter - "Mission Sonic Boom"
https://www.youtube.com/watch?v=H42rYxI6PVI
The Soviet MIG-25 Foxbat a claim it could visit the 'Edge Of Space'
https://www.youtube.com/watch?v=rApXqj6WS2E

Highest aeronautical flights of 120,000 + ft

Last edited by Mars_B4_Moon (2023-10-03 11:25:41)

Mars_B4_Moon · 2023-11-29 06:28:17

A Tiny Quadcopter Could Gather Rocks for China’s Sample Return Mission

https://www.universetoday.com/164526/a- … n-mission/

tahanson43206 · 2023-11-29 08:14:43

Thanks to Mars_B4_Moon for finding and posting the link in #141

The article at the link contains a link to the original paper, which may be of interest to those who are doubtful.

Here is a pertinent snippet...

The numerical simulation shows that the Mars quadcopter generates a thrust of 19.2 N and requires a power of 900 W at a speed of 4645 r/min. The Reynolds number of the rotor at 75% R is 7814, and the tip Mach number is 0.81. The thrust-to-weight ratio of MarsBird-VII reaches 1.3 with a take-off mass of 4 kg, which is enough for hovering and cruising on Mars.0

The design payload for this 4 Kg system is 100 grams. I dug out a small postage weighing machine and found that 100 grams is a ** lot **. A flip phone weighs 118 grams. A medium sized screwdriver came in at 90 grams. That is a sturdy heavy duty screwdriver. It really feels substantial. I think that delivery of 100 grams of rock fragments to a lander would keep the lander busy for quite a while.

At this point, the quadcopter is still in the numerical simulation stage, but I gather from the paper that early indications of potential success in implemtation look favorable. The snippet above reports that the tips will be well under the speed of sound on Mars.

I read a comment in one of the forum posts recently, in which the writer worried about the sound that might be produced by one of these machines, but I thought the worry was misplaced. No human ears are going to be out in the open on Mars, and the low density of the atmosphere is going to mitigate any forces that might be generated.

(th)

GW Johnson · 2023-11-29 11:03:04

Subsonic tip speed will prove to be a real technology limit, one that prevents using higher speeds to offset the lower density. You may not believe in noise from a supersonic propeller, but history says it is incredible, here on Earth. The thinner Martian atmosphere reduces the noise, but cannot eliminate it.

Of more concern is the fundamentally-unsteady nature of shock-induced flow separations on supersonic blades. That increases unsteady unbalanced forces, inducing severe vibrations. This (along with the noise) was seen decades ago experimenting with supersonic propellers right about the end of WW2. Those severe vibrations mean a very short fatigue life for the blades. (The noise impacting adjacent skins shortens the fatigue life of those skins, too.)

And don't try to tell me there is no fatigue with a composite blade. Despite the desired beliefs going in, there is demonstrable accumulating damage leading to failure, in composite aircraft materials, although the detailed mechanism of this damage is different from the propagating cracks seen in metals. There is cracking in the matrix around the fibers, yes, but much more important is the delamination between fiber and matrix that increases with time of exposure. Sounds like "fatigue" to me, even if you don't want to use that word to describe it.

Yes, I was the one who raised the noise issue with supersonic blades. I told the tale of the just-supersonic blade tips of the propellers on the Tupolev "Bear" bomber at takeoff power. Those could be heard quite clearly inside submerged submarines, only a mile or three away.

GW

Last edited by GW Johnson (2023-11-29 11:11:52)

Calliban · 2023-11-30 02:52:06

Fixed wing vehicles using ramjet engines would appear to be the only way aerodynamic flight on Mars will work at scale. The high take off and landing speeds would seem to require rocket propulsion. It isn't safe to land at 600mph. So the vehicle must cancel forward velocity using rocket propulsion and then achieve a propulsive landing, using rocket thrust to balance gravity during descent.

When all is said and done, would such a vehicle actually have any range or payload advantages over a purely ballistic rocket vehicle? With a ballistic vehicle, you accelerate as hard as possible to minimise gravity losses. You then coast on a suborbital trajectory, most of which is outside of the sensible atmosphere without friction. On a small planet like Mars, the gravitational acceleration falls off more rapidly with increasing height. A ballistic vehicle can take advantage of that as well, with a large part of its trajectory taking place in a weaker gravity field. The thin Martian atmosphere complicates aerodynamic lift but is actually favourable to rocket engine performance.

I don't know the answer to this. It is GW's area of expertise. But the need for a propulsive landing would add a lot of weight to a supersonic aircraft, as you need a seperate set of rocket engines for takeoff and landing.

Last edited by Calliban (2023-11-30 02:58:17)

Mars_B4_Moon · 2023-11-30 08:42:32

In the early part of the Space Shuttle Program or STS design process they had two aircraft and one piggy back on another as part of U.S. space shuttle concept, the original North American Rockwell Shuttle delta wing designs, DC-3 North American Aviation (NAA), there were also plans to go to Mars build space stations and other things and then suddenly future NASA budgets would be only a fraction of Apollo-program levels and keep getting smaller. The idea was to have a Fully reusable launch vehicle, there was also a Nuclear Shuttle ferry and a Space-Tug, here is a link with Rockwell 1971, North American Aviation (NAA) pics, the Shuttle design was changed maybe for time and economic reasons, maybe with people on Mars and Titan they would return to those early concepts https://web.archive.org/web/20120313084 … huttle.htm

A young guy does a talk on the S-turns and banking in reentry path, the Heading Alignment Cone (HAC) spiral path used to guide NASA's Space Shuttle, the ball of plasma deceleration, energy management of velocity and decent, de-orbit burn and 'How to Land the Space Shuttle'

https://www.youtube.com/watch?v=Jb4prVsXkZU

Last edited by Mars_B4_Moon (2023-12-01 07:22:54)

GW Johnson · 2023-11-30 10:45:02

I actually liked the piggy-back two-stage rocket airplane idea for the space shuttle. It made more sense than the cluster-f**k they ended up with, which was driven by the congressional politics of funding, coupled with congressional micro-managing of NASA's detailed objectives.

However, do not be fooled by the wings on those airplanes in such designs. They serve only at entry, descent, and landing for the two stages.

Rockets are more efficient when launched vertically onto a ballistic gravity-turn trajectory, non-lifting. This has been known for decades now. If winged, the wings are an inert mass and parasite drag penalty during ascent. The trade-off is accepting those penalties to get cross-range divert capability and (most importantly) runway landings.

Landing on a runway without saltwater exposure is simply way more potentially reusable. Further, these runway landings are simpler and easier to deal with, instead of parachute splashdowns or parachute landings on land that require last-second rocket deceleration-assist to be survivable with crews (exactly the way the Russians do it with Soyuz). There is also an effective practical size limit for landing things with parachutes. Bigger simply requires wings.

There is a whole set of reasons why proposals to fly winged lifting ascents from the surface into Earth orbit have never been successful. The corridor to do so is quite narrow, limited by insufficient-lift-to-fly in the thinner air just above it, and by excessive and very nonsurvivable heating just below it. Plus, exposure times to the heating are a lot longer during ascent than descent, because your speeds are simply lower during ascent. Doing this requires extremely careful design and material selections that can get rather exotic. Depending upon your design details and material selections, there may be no solution space at all.

The same thin air that limits lift (when weight is not affected by air density) also limits the thrust of ANY and ALL airbreathing engines of ANY TYPE WHATSOEVER! Airbreathing thrust is crudely proportional to the ambient air pressure, which rocket thrust is affected only in a minor way, and actually increased slightly in the thinner air. That is the so-called "service ceiling" effect: insufficient thrust to maintain level flight, much less climb or accelerate.

Which thin-air lift and thrust problems coupled with high-speed heating problems, is EXACTLY why scramjet-to-orbit-speed is utter nonsense! It was BS in the 1980's with the X-30 design concept, and it still is today. Yet I still see it proposed all the time by people ignorant of these facts, and even by some who should know better, but choose to ignore the facts, having been seduced by notions of "higher airbreathing Isp". They do that despite the other inconvenient fact that current launch technology rockets have better Isp than any possible scramjet, as you exceed about Mach 8-to-12.

Thus only rockets could power such a lifting ascent, and we already know they are much more efficient when used on the non-lifting gravity turns, where the drag losses are fairly low, instead of overwhelmingly enormous.

While the numbers are different, the same basic considerations apply on Mars, compounded by the thin air effects upon feasible winged landing speeds. You are simply better off using your rockets in a vertical-launch gravity turn, coasting frictionless outside the atmosphere. That's true on Mars just like it is here on Earth. Any wings would be only for entry, descent, and landing. And in that thin air on Mars, your wing loadings (weight divided by wing area) must be incredibly low to have a safe and practical landing speed.

That's true even accounting for the lower gravity on Mars. Weight is reduced by only a factor near 2.6. Density is reduced by a factor significantly exceeding 100. The wind pressure that creates lift (acting upon the wing area) is proportional to density, and to velocity squared. Lift must equal weight. All else equal, you would need about 6.5 times higher speeds at Earthly wing loadings, or 6.5^2 ~ 40 times larger wing areas at Earthly speeds. There is no way around that conundrum with airplanes on Mars.

Which in turn is why the propulsive landing is likely far more attractive on Mars. If you can't practically use wings for landing, and ballistically-launched exoatmospheric coast is more efficient, then why bother with an airplane?

GW

Last edited by GW Johnson (2023-11-30 11:26:36)

tahanson43206 · 2023-11-30 12:23:55

For GW Johnson!

Just FYI ... the NASA article that started this topic back in 2003 has been removed.

This is pure speculation on my part ... one possible explanation for removal of the article from their web site is that they do not want anyone to remember it.

(th)

Calliban · 2023-11-30 12:56:20

GW, how is lift effected by the transition from subsonic to supersonic speeds?

tahanson43206 · 2023-11-30 13:44:25

For Calliban re GW's work on the Rocket Hopper and the LMO taxi ...

GW has been working on designs for these two roles, and I am so close to his work that I can no longer remember how much has been published on the forum. It is entirely possible we have been concentrating on the NSS connection (to make YouTube videos) that we have neglected the NewMars updates.

Please let me know if you have caught any of the posts we might have done, or if we need to add new posts.

***
For GW ... your current design (as I understand it) shows that heat shields are not required for either the Hopper or for the LMO taxi models. So my follow up question is ... is there any benefit to the "lifting body" shape for either vehicle, or is that just wasted mass, as I expect.

(th)

GW Johnson · 2023-11-30 17:20:20

Calliban:

For lifting wings of fairly conventional design, there is not a whole lot of change in the lift curve slope as you transition from high subsonic to low supersonic. There is a lot more change in the parasite drag of such wings, which is usually a fairly small contributor to aircraft drag.

The change in drag across Mach 1 is quite substantial, for just about any shape you can imagine. Drag coefficient roughly doubles sharply as you approach Mach 1, peaking about Mach 1.1, and then gradually declining to roughly-constant levels about the Mach 3 blunt-object hypersonic point. Meanwhile, dynamic pressure varies as Mach squared, so this effect shows up as a ripple across Mach 1 in a rapidly-increasing drag force curve vs Mach.

Lifting bodies have a lift that is usually best understood as a component of the crossflow drag force. Their lift coefficients are thus more strongly-dependent upon Mach number as you cross Mach 1.

Tahanson43206:

What I actually found was that returning at low entry angle from low Mars orbit, the hopper did not need a heat shield for my specific vehicle shape and mass. Exposed metal with a dull, dark finish could cool re-radiatively without exceeding service temperature limits, for a variety of attractive materials. Those include SS316L and Inconel X-750. They do NOT include SS304L, titanium, aluminum, mild carbon steel, D6AC alloy steel, or organic composites.

Suborbital trajectories inherently entered steeper, but below about 2.7 km/s speed at entry interface, they did not need a heat shield, either, given the same kind of construction and materials. The long-range suborbital trajectory at 3.6 km/s needed some heat protection on and near the stagnation zone, in order to to avoid needing a real exotic alloy, like Rene-41 or Alloy 188.

There are a variety of options to provide that heat protection: ceramic tiles, ceramic blankets if they can be secured against wind shear forces, any of the ablatives, and even a thin sheet of one of the exotic high-temp metals over some mineral wool insulation. The ablatives would not be reusable. The other choices are reusable, at least potentially.

GW

Last edited by GW Johnson (2023-11-30 17:26:26)

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