Feasibility of identifying natural landing strips for winged aircraft from orbit

[Robotbeat]

So I’m wondering if a combination of photogrammetry and texture matching with ground-truthed imagery from the various surface probes could identify suitable natural flat landing strips on Mars for horizontal landing aircraft. Obviously large wheels and low enough landing speeds would be needed (in spite of the low density), but perhaps some sandy or otherwise flat place could be found to meet the requirements with big enough wheels and slow enough stall speed.

Perhaps you’d still need a rover or a helicopter to ensure a safe landing site free of boulders bigger than the tires could handle, but it’d be interesting to see if any suitable spots could be found from orbit.

It might make logistics on Mars easier to have existing landing strips and ability to use wing borne aircraft without the massive range penalty of VTOL.

[freddo411]

It would be interesting to work the napkin numbers to flesh out this thesis.

The shuttle's landing speed was crazy fast, even in the Earth's atmosphere.   Mars is roughly 2 orders of magnitude less dense, although the lower gravity helps a bit.

My intuition is that the range of possible stall speeds are crazy high to supersonic  --depending on the surface to mass ratio.   Keep in mind the shuttle is already a mass optimized vehicle

I don't think high speed horizontal landing can accommodate anything but a  very long surface that is very smooth along its entire length

[whitelancer64]

The main problem with a runway on Mars is it would need to be very, very long - I would guess at least 5-10 km even for a relatively small passenger / cargo aircraft - because the air is so thin that takeoff and landing speeds must be very high (close to supersonic) to generate lift, requiring a very long distance to roll up to flight speeds / brake from flight speeds, and even small bumps at that speed would likely be diastrous. You might be able to use a slightly shorter runway at very low elevations.

Anyway, I doubt there are very many reasonably flat / smooth areas on Mars that long. On the other hand, you could probably fairly easily identify long strips that are mostly flat / smooth that a bulldozer could make more flat / smooth. We have maps of Martian elevation with sub-meter accuracy from laser altimetry.

[Robotbeat]

Why long? Just use air brakes or a parachute. For launch, use a winch, a catapult, or a rocket assist.

[Robotbeat]

I think if you get the wing loading very low, like for Helios, the landing speeds would be fairly reasonable. A high stall speed might be preferred for long distance and more rugged aircraft tho.

[Robotbeat]

At low altitudes, Mars has an atmospheric density about 2% that of the earth. And its gravity is about a factor of three lower. That means there’s a factor of 18.9 difference in lift to account for. Since lift is proportional to speed squared, you can take the square root of that to see how much faster an aircraft will have to travel on Mars than on earth to maintain level flight. About a factor of 4.34.

For a human powered aircraft, you can have flight speeds as low as 8mph. https://en.wikipedia.org/wiki/MacCready_Gossamer_Condor

So flight speed on Mars would need to be about 35mph. that’s not bad at all. So maybe we can afford not to make the airplane out of Saran Wrap.

If we said 200 mph is the maximum speed for landing on Mars, that means a similar earth design would need to be capable of flight of about 46mph. Tundra tires max out at around 120mph, so maybe we need more like a 28mph Earth minimum level flight speed for a viable Mars aircraft. Maybe the return of biplanes??

[whitelancer64]

Why long? Just use air brakes or a parachute. For launch, use a winch, a catapult, or a rocket assist.

Because it will take a while to ramp up to ~800 km/h for takeoff and to slow down from about that speed when landing.

Parachutes might be okay but then you need to pack them back up when you want to take off again. Only a few examples of aircraft that used them on a regular basis.

If you have a winch, catapult, or whatever, then it's no longer an unprepared runway. You'd have the runway smooth and graded and you might as well make it as long as you need, then you wouldn't really need anything special to assist the aircraft to take off. Or you might as well have catch wires like an aircraft carrier for landing.

But then this thread needs to be "Feasibility of building an aircraft carrier deck on the surface of Mars"

[whitelancer64]

At low altitudes, Mars has an atmospheric density about 2% that of the earth. And its gravity is about a factor of three lower. That means there’s a factor of 18.9 difference in lift to account for. Since lift is proportional to speed squared, you can take the square root of that to see how much faster an aircraft will have to travel on Mars than on earth to maintain level flight. About a factor of 4.34.

For a human powered aircraft, you can have flight speeds as low as 8mph. https://en.wikipedia.org/wiki/MacCready_Gossamer_Condor

So flight speed on Mars would need to be about 35mph. that’s not bad at all. So maybe we can afford not to make the airplane out of Saran Wrap.

If we said 200 mph is the maximum speed for landing on Mars, that means a similar earth design would need to be capable of flight of about 46mph. Tundra tires max out at around 120mph, so maybe we need more like a 28mph Earth minimum level flight speed for a viable Mars aircraft. Maybe the return of biplanes??

I was assuming you were talking about a small crew or cargo carrying aircraft, something that could do useful work, not an ultralightweight gossamer condor.

150 mph is close to the minimum landing speed for most commercial aircraft on Earth. 4.34 x 150 = 651 mph

[Barley]

Why long? Just use air brakes or a parachute. For launch, use a winch, a catapult, or a rocket assist.

Not much air.

If you to use a rocket assisted takeoff, if your rocket can push you at 1g the gravity losses for a takeoff that skims a few meters above the ground are quite small, so you don't need a "runway", just no vertical obstructions or better yet a downhill slope.

[Bob Shaw]

What about landing *uphill*?

[Jim]

Not feasible for winged landing.  Too fast.

[Twark_Main]

wing borne aircraft without the massive range penalty of VTOL

[citation needed]

[Twark_Main]

I think if you get the wing loading very low, like for Helios, the landing speeds would be fairly reasonable. A high stall speed might be preferred for long distance and more rugged aircraft tho.

Low wing loading = large wing area per payload mass = large wing mass penalty.

[Barley]

I think if you get the wing loading very low, like for Helios, the landing speeds would be fairly reasonable. A high stall speed might be preferred for long distance and more rugged aircraft tho.

Low wing loading = large wing area per payload mass = large wing mass penalty.

Or wings made of saran wrap.

[Robotbeat]

 

I think if you get the wing loading very low, like for Helios, the landing speeds would be fairly reasonable. A high stall speed might be preferred for long distance and more rugged aircraft tho.

Low wing loading = large wing area per payload mass = large wing mass penalty.

Not really. Remember the gravity is lower as well, so there are some structural advantages to Mars. Biplanes on Earth can have big wing areas with not that bad of a mass penalty even using century old construction techniques. I think the biggest penalty is wetted area drag, which is less important if the air is low density.

People act as if the only way you can make an airplane on Earth is with heavy aluminum transonic wings and a landing speed of 120mph or more like a jet. But some of the most produced airplanes in the world are utility aircraft with 30mph stall speed and lightweight wing skins over an aluminum frame (could be upgraded to carbon fiber), the Antonov An-2. Heck, some of the main reasons not to use wood and canvas for airplane construction is that they can get destroyed by moisture (or termites, etc), not a problem on Mars… https://www.planeandpilotmag.com/scroll/1-waco-ymf-5/

[JAFO]

People act as if the only way you can make an airplane on Earth is with heavy aluminum transonic wings and a landing speed of 120mph or more like a jet. But some of the most produced airplanes in the world are utility aircraft with 30mph stall speed and lightweight wing skins over an aluminum frame (could be upgraded to carbon fiber), the Antonov An-2. Heck, some of the main reasons not to use wood and canvas for airplane construction is that they can get destroyed by moisture (or termites, etc), not a problem on Mars… https://www.planeandpilotmag.com/scroll/1-waco-ymf-5/

WADR, lot of bad info in this post.

The "Ant" is a bad example to use. It's got a metal frame and fuselage skin, fabric wings/tail/control surface coverings, and a tricked out wing that added a bunch of weight to make the STOL magic work. While it theoretically has no stall speed, upper 20's/low 30s are generally used.  https://www.an2flyers.org/an2specs.html

Can't think of any modern LSA/LSX aircraft made from wood, most are made from 6061 or carbon fiber, and the fabric is actually a polyester blend called Polyfiber coated with a polyrubber blend. https://www.conaircraft.com/polyfiber

It all depends on your mission. Want to fly anytime/anywhere through (almost) anything? Call me and you can charter my 787. Need something to fly on another planet? My hat is off to and I am incredibly proud of the Ingenuity project team. https://mars.nasa.gov/people/?category=helicopter

[JayWee]

Why long? Just use air brakes or a parachute. For launch, use a winch, a catapult, or a rocket assist.

...
Parachutes might be okay but then you need to pack them back up when you want to take off again.
...

And don't forget the dust.

[chopsticks]

I wonder about an aircraft type like a powered glider with really long wings and a shallow cord. Those can fly really slowly, have tons of lift, and are very efficient aerodynamically.

I mean, it works pretty well on Duna in KSP..

[Robotbeat]

I wonder about an aircraft type like a powered glider with really long wings and a shallow cord. Those can fly really slowly, have tons of lift, and are very efficient aerodynamically.

I mean, it works pretty well on Duna in KSP..

Exactly. need to get the landing speed slow enough that you can land on natural flat areas of Mars with tundra tires.

The older 737s had kits for landing on unpaved (i.e. gravel) landing strips. The kits included a shield attached by the landing gear that keep rocks from spraying up and hitting parts of the airplane. Those planes land at like 150mph. The landing strip can handle obstacles up to 3 inches high. So it's doable in principle.

[Robotbeat]

People act as if the only way you can make an airplane on Earth is with heavy aluminum transonic wings and a landing speed of 120mph or more like a jet. But some of the most produced airplanes in the world are utility aircraft with 30mph stall speed and lightweight wing skins over an aluminum frame (could be upgraded to carbon fiber), the Antonov An-2. Heck, some of the main reasons not to use wood and canvas for airplane construction is that they can get destroyed by moisture (or termites, etc), not a problem on Mars… https://www.planeandpilotmag.com/scroll/1-waco-ymf-5/

WADR, lot of bad info in this post.

Nothing is incorrect in what I said.

The "Ant" is a bad example to use. It's got a metal frame and fuselage skin, fabric wings/tail/control surface coverings, and a tricked out wing that added a bunch of weight to make the STOL magic work. While it theoretically has no stall speed, upper 20's/low 30s are generally used.  https://www.an2flyers.org/an2specs.html

Why is it a "bad example"? You just kinda showed that it's viable. It doesn't use wood, but it does use fabric and has very low landing speed.

Can't think of any modern LSA/LSX aircraft made from wood,

There are some still in production which are. The full article from the link I posted says:
https://www.planeandpilotmag.com/news/pilot-talk/10-wooden-airplanes-you-can-buy-or-build/

As we progress well into the second century of flight, most of us take to the sky in machines of metal or advanced composites like carbon fiber and Kevlar. The science is solid and techniques well established for flying machines of these materials. But if you step away from the mainstream types most commonly decorating the ramp at your local airfield, you may well stumble across wooden airplanes that survive as antiques, warbirds and homebuilt designs, as well as a few types built more recently. There are even a few designs in current production—one featured below is a throwback to the days of old, while another is a Light Sport Aircraft utilizing a wood wing to stay below the 1,320-pound gross weight limit.

most are made from 6061 or carbon fiber, and the fabric is actually a polyester blend called Polyfiber coated with a polyrubber blend. https://www.conaircraft.com/polyfiber

It all depends on your mission. Want to fly anytime/anywhere through (almost) anything? Call me and you can charter my 787. Need something to fly on another planet? My hat is off to and I am incredibly proud of the Ingenuity project team. https://mars.nasa.gov/people/?category=helicopter

Yeah, carbon fiber and other advanced modern materials are the obvious choices, but it's worth reconsidering things that the environment of Mars may enable due to lack of moisture and rot.