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Flying on Mars
jimharris submitted a bunch of links about flying on Mars: "X-Plane's author Austin Meyer is working out the details of flying on Mars. Meyer has taken his system and adapted it for the conditions on Mars and has discovered a lot about what it would take to fly on Mars, where the atmospheric pressure is 1 percent of Earth, and gravity one third, but laws of flight remain the same. Flying becomes difficult, and landing almost impossible. Other people are working with NASA to create Entomopters engineered to meet Mars conditions. More ideas about the concept can be found at PBS's Scientific American Frontiers. A quick search at Google will reveal many people are thinking about flying on Mars." It's a beautiful challenge - how to fly in a situation where everything you "know" about flight is wrong.
I always wanted to get a Flight Sim with accurate physics (and of course landscapes.) for the solar system planets and satellites. I hope that a game with this theme will show up one day. Maybe hacking XPlane would work?
PPA, the girl next door.
-- I feel better now. Thanks for asking.
Helicopters aren't fuel efficient, nor are their rotor "wings" good for lifting in a one percent atmosphere. A plane like the U-2 would be the obvious choice, except for the horrendous storms on Mars.
The Gardener
--
Actually, landing is always easy. For example, NASA has landed several spacecraft on Mars in the last few years.
The difficult part is managing to keep your vehicle in one piece as you land.
What about that document, eh? Some fun RANDOM CAPITALIZATION. Looks like the entire document was written by Zippy the Pinhead, but without the random statements. An interesting document. Perhaps we're going to have to use slow "zepplins" on Mars. It could acutally be a better idea. The zepplin is floating about 60m above the surface, and it has four thrusters. The one the the back is the most powerful. They are arranged so that the thrusters are at right angles from each other (or maybe a "peace-sign" arrangement is better?).
Just a thought. Flames will be used to save on energy bills.
Everything is mainstream now.
We have large lifting craft that require almost no runway for takeoff and landing.. they are they relatives to the blimp.
Same laws apply.. sure there is less of an atmosphere.. but you also have one third the gravity to contend with. The main problem with such craft on the martian surface would be the fact that 1) they are huge, and 2) they are light. With the storms that have been witnessed on mars recently, storing such a craft would be a nightmare if you didn't collapse it and store it. Lets not forget the possibility you COULD be in the air when such a storm kicks up.. nothing could save your arse if that happened..
I think this will be the way we go.. because a dirigible could be packed into a small payload area for transport to the martian surface. The added bonus is that Mars has VERY little oxygen in the atmosphere.. so it becomes safe to fill the dirigible with hydrogen as opposed to helium, giving you much more lifting power.. the problem comes with storing compress hydrogen when you deflate these behemoths.. wouldn't want to store the tanks near an oxygen rich environment like say.. in the living structures or greenhouses.. =)
. echo -e \\04 >
Helicopters won't work well on mars, you'll need to have your props spinning 10 times faster to get the same lift, which will be somewhat diffucult, no?
It might work actually, but AFAIK there aren't any easily manufacturable materials that will stand up to the centripetal forces, since there will be 100 times as much force on the end of the prop (centripetal force is the square of velocity). You might be able to do this by increasing the surface area of the prop (longer blades, or more blades).
Also, nasa's probes once they get into the atmosphere still use parachutes and rockets to slow down to a decent speed and then giant inflatable bubbles to bounce along, but you only use that when you're below a few hundred knots. In the article, it says, that you'll be going 400 mph in a well designed plane, there's no way you're gonna just bounce around if you hit the ground like that... Same inertia, right? imagine that its like having 10 times more inertia...
also, I've seen a few articles, he mentions red sky on mars.
I've seen no good proof to believe the sky is red, if its because the ground is red, think about the earth, in the middle of a desert, or forest, is the sky yellow or green? looking at that, you'll often think they'll be bluer than at the beach (where it tends to look grey, I live at a beach town).
Because the colour of the sky is caused by Raleigh scattering (or other scattering effects), the effect (based on the size distribution of particles in the atmosphere) is the same on Mars as it is Earth.
Somewhere, if you hunt around for photos from the surface of mars, and correct using say, photoshop, for the colour (look at the parts of the probe you can see in the picture and return them to their original colours, usually white or metal, unless its an american flag), the sky will be blue.
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The highest-altitude balloons ever flown on Earth topped out at 100,000 feet. That's the altitude where Earth's atmospheric density finally drops to the point where it reaches Mars' at "sea level".
By comparison the x1/3 lower gravity will not be that much help - you will need a huge, thin balloon to carry any weight at all, and (a) collecting the necessary quantity of gas; and (b) inflating it safely both become major challenges.
I think this is why we don't see mention of balloons / zeppelins on the NASA webpages.
-Renard
... who read that article and thought "too bad they didn't call these vehicles 'ornithopters' "?
- Mike
And more. For example...If you want to convert the surface of the planet to a temperature where you can stay outside without a space suit you need to heat upo the atmosphere. The best way to do that is to use Carbon Dioxide as it is a natural greenhouse gas. However, if your eventual goal is to make the atmosphere breathable, you need to do something about the vast quantities of Carbon Dioxide.
How about a huge focusing lens positioned in a aerosynchornous orbit that collects those solar rays that woud just miss Mars and focuses them back toward the3 planet to heat it up.
How about drilling huge holes in the surface to realease Geothermal energy into the atmosphere to heat things up.
And so on. If you are interested in Mars, read the book. He addresses a lot of the major issues . Even if he is off on certain topics (it is a novel after all), it is a great step forward in Science Fiction
Open Source Identity Management: FreeIPA.org
Did you even read the article?
The laws of physics are the laws of physics -- and they're the same on Mars. Yes, you'll need larger wings, and will have to fly *much* faster than you would here -- but 1) we can easily calculate all these factors (like Austin did) and 2) we've already got planes here on Earth that fly in somewhat similar conditions (up at 100k feet -- not 1/3rd Earth gravity, but the same weak atmosphere (well, it's not mostly CO2, but there are realms where the Reynold's numbers are the same.)
The only way that `everything we know about flight' could be wrong is if `everything we know about flight' corresponds to `Give it full power, wait a few seconds as it accelerates, and then pull back on the stick at 60 knots, and your Cub will take off'. Sorry, but we do know more than this. If we didn't, this article wouldn't even be here.
Other /. posters have commented about the horrible `storms' on Mars. I'm not so sure they'd be a problem for anything but a blimp -- sure, the wind may be blowing at 200 knots -- but that's only 1/3rd of your cruising speed (and only 20 knots on your Earth-calibrated air speed indicator -- it wouldn't even faze a guy in a spacesuit walking on the surface.) Hell, a 400 knot headwind might allow you to take off and land in a reasonably short space :)
What would be even neater than flying in Mars would be flying in Venus or Jupiter. As I understand it, Venus has a thicker atmosphere, so you could fly slower and turn quicker. Jupiter is a gas giant, so as you get deeper and deeper the atmosphere would get thicker and thicker -- of course, the pressure goes up too, and since it's mostly hydrogen, you're likely to have a much higher pressure than you'd find on Earth before the atmosphere would be as `thick' as it is here, but it would certainly be doable.
I was surprised that Austin Meyer doesn't understand that the thrust of jet engines in either direction doesn't depend on the atmosphere density, unlike prop engines. Am I missing something?
Same laws apply.. sure there is less of an atmosphere.. but you also have one third the gravity to contend with. The main problem with such craft on the martian surface would be the fact that 1) they are huge, and 2) they are light. With the storms that have been witnessed on mars recently, storing such a craft would be a nightmare if you didn't collapse it and store it. Lets not forget the possibility you COULD be in the air when such a storm kicks up.. nothing could save your arse if that happened..
.38g gravity of of Mars really helps - landing vertically should be a cinch.
Fortunately, the laws of rocketry also continue to apply. The
As for structural lightness, remember, the air is very thin. What looks like a huge storm on a satellite photo just isn't going to going to blow anything over on the ground. It's true, Martian winds can pick up small particles, and researchers are still trying to figure out how that happens - vortices maybe, and the oarger particles probably don't get very far off the ground. Global dust storms would contain only the finest particles.
Blimps/dirigibles on the other hand... with less than 1% atmosphere, you have less than 1% of the bouyancy. In the end your balloon will have to be 30 times bigger to lift the same mass. This means that, while a balloon might work, a dirigible won't. Too much structure required.
Life's a bitch but somebody's gotta do it.
Wouldn't helicopters work best on mars? Mars is smaller (I forget by how much).. so I doubt anyone's gonna need a 747 up there any time soon :P
RTFA. The basic problem is that you indicated airspeed is 1/10th the acutal airspeed, which means that your lift is 1/10th what it would be if you were on earth.
So of your main rotor is moving at a very conservative 200RPM providing enough lift for takeoff, then that same rotor would have to move at 20,000RPM in order to take off on Mars. This won't work very well because it will be very inefficient and probably make it difficult to keep the body of the helicopter stable.
Designing a helicopter to fly on mars would be a very interesting and difficult task indeed.
LedgerSMB: Open source Accounting/ERP
Blimps/dirigibles on the other hand... with less than 1% atmosphere, you have less than 1% of the bouyancy. In the end your balloon will have to be 30 times bigger to lift the same mass. This means that, while a balloon might work, a dirigible won't. Too much structure required.
On the contrary.... here's a little math..
Size of balloon for dirigible (and volume..)
Volume of ellipsoid (a=semimajor, b= semimean, and c=semiminor axes) = (4/3)*pi*abc.
A=100m B=40m C=30m
V=5.03x10^5 M^3
V=5.03x10^8 L
Now for temperature and pressure...
Assuming Tmars to be avg. -50C = 223K
And assuming we inflate to 2atm(mars) = 0.02atm(earth)
PV = nRT
n = PV/RT = (0.02atm * 5.03 x10^8 L) / (0.0821 L atm/mol K * 223 K)
n = 2.75x10^5 moles within balloon...
M(H2)=2 g/mol * n = 5.5x10^5 grams
yeah, that's a LOT of hydrogen.. but lets continue
For the atmosphere this hydrogen is displacing...
Which, BTW, is over 95% CO2, unlike earth which has a much lighter atmosphere for a given pressure..
PV = nRT
n = PV/RT = (0.01atm * 5.03x10^8 L) / (0.0821 L arm/mol K * 223 K)
n = 1.38x10^5 moles of atmoshpere displaced
M(CO2)=44 g/mol * n = 1.21x10^7 grams
Taking the difference, we find that there is 115.5x10^5 grams or...
11550 kg of lifting force here...
Of course we might need to put more H2 into the balloon to have it hold it's shape.. for each martian atmosphere of additional pressure we inflate the craft with, go ahead and reduce the lift by 275 kilograms. Double the local atmospheric pressure should be sufficient.
Now, can we build an airship of that size and keep it's weight under 10000 kg?
(Mind you that IS 30000kg here on earth)...
I think it is safe to say it is more than easily accomplished.
.
. echo -e \\04 >
You're thinking rocket engines.
:)
Rockets carry their own fuel and as such provide their own thrust.
Jets and props require an atmosphere to provide the gas necessary to provide thrust.
Sorta like... imagine outboard motors and water jets out of the water... not much thrust
GPL Deconstructed
I was surprised that Austin Meyer doesn't understand that the thrust of jet engines in either direction doesn't depend on the atmosphere density, unlike prop engines. Am I missing something?
Disclaimer, I am not an aeronautical engineer.
Actually, you are incorrect. The challenges for jet and prop engines are different in very thin atmospheres, but the basic problem is that with 1% of the earth's atmosphere, you cannot take enough O2 into your engine to get the engine running. OK. Crash course in turbofan engines:
The engine containes a few parts:
compressor->combustion chamber->turbine
The turbine runs the compressor, often generates electricity and usually also runs a secondary compressor or fan ourside fo the combustion pipeline used for increased thrust.
THe secondary compressor's thrust output, like a propellor's is purportional to the strength of the atmosphere (less air, less thrust). This is the first main problem. Unlike the propellor, the fan's thrust is mostly in the form of reaction mass and there is no real Bernouli's effect. Again, this reduces probably 10fold at 1% atmosphere.
The second in in the jet pipeline. The turbine compresses air in the combustion chamber which is mixed with fuel and burns. The jet of hot gasses pass by the turbine which runs the compressor and produces thrust in the form of reaction mass (for each action...). The combustion is limited by the oxygen intake which goes down as the air supply goes down, but not as fast as it does for a propellor (assuming adequate O2).
For take-off and landing, the turbofan engines also produce thrust in a third way. If you have been reading this so far and asked, "what about the shape?" I will answer this question. The shape is designed to produce a ducted fan effect, drastically increasing thrust at low speeds. Basically, as air gets sucked into the engine, it forms a low-pressure ring around the lip of the rim which means that the rim of the engine gains forward lift (similar in principle to the Hillard Flying Platform). This thrust would also be decreased 10 fold in the thin martian air.
So yes, jet engines do depend on atmospheric density. Their curve is just flatter than that of a propellor (which are basically forward spinning wings similar to helicopter rotors, but with more fan and less wing).
LedgerSMB: Open source Accounting/ERP
Fortuna Wolf said:
Somewhere, if you hunt around for photos from the surface of mars, and correct using say, photoshop, for the colour (look at the parts of the probe you can see in the picture and return them to their original colours, usually white or metal, unless its an american flag), the sky will be blue.
In spite of this potential troll, I feel compelled to point out that the reflectivity of a surface will naturally reflect most electromagnetic components of its environment. This goes for white surfaces. So by "correcting" the color balance of such a surface, such as appendages of the mars probes, you have in fact only inferred the original environment from which your photo was based.
Mojotoad
I hate to nitpick, but this is so wrong I had to point it out.
...
;)
10000kg on earth is still 10000kg on mars.
Taking the difference, we find that there is 115.5x10^5 grams or...
11550 kg of lifting force here..
Now, can we build an airship of that size and keep it's weight under 10000 kg? (Mind you that IS 30000kg here on earth)...
I'll assume based on the rest of the post that you know the difference between mass and weight...
Other than that and the fact that some of the calculations you show have the wrong answer (but strangely the right final answer, where'd you pull that out of?), you're right, a blimp should work ok on mars.
Would I be able to change the weather in the game too? Is the weather the same on Mars as it is on Earth. The article doesn't give too much details about this part. Is this an Hollywood to represent the Red planet weather as really tough? Thanks for the info.
PPA, the girl next door.
-- I feel better now. Thanks for asking.
Wonderful instrument...aligns itself at right angles to the planet's spin, making it easy to determine in what direction lie the poles.
You're using her as bait, Master!
Bought the game back when the announced intention of a Linux game, but assume this will occur after the release of the OSX varient. Its a fun sim, with alledgedly more accurate flight dynmaics than MSFS (Microsoft Flight Sim), indeed flying on this sim seems smoother. MSFS does have a lot better scenery though.
What is incredible is that Austin Meyer is the sole developer of this program, I thought development like this had ended since the early 90's.
After flying on Mars, its very hard! Reality is certainly stranger than fiction in many instances. The scenry and effects on Mars are very alien indeed, definately worth a try.
Matt
I have worked on physics models for atmospheric effects in a flight sim for the Kitty Hawk project. There are a lot of issues surrounding flying a plane on mars, but it is not much different.
The biggest obstacle (and one in which I haven't read yet.. so I'm posting) is the differences in speed of sound. People say, "Get bigger wings" and "fly faster" unfortunately this doesn't work as well as would be expected. You basically have to design your plane to fly super-sonic when it is travelling roughly 180 knotts (Martial sea level vs. earth equiv is around 100K feet, reduction in speed of sound..don't remember the exact numbers -- this was years ago that I worked on the project)
This isn't the easiest of tasks, but, they did it. - the major obstacle the project faced (we did the sim, as show in the picture - CMEX did all the "real" work) faced was efficient fuel. The final engine was Hydrazine powered, as the whole plane had to be exceptionally light weight and cover a large stretch of valles marineris.
Anyway, it's been designed for years now... hope you found my drivel interesting.
And yes, it is cool to work at NASA.
Dacels Jewelers can't be trusted.
The same convention used for the sun and (most of) the other planets would apply. Thus virtually all of the "north" poles (Uranus is an exception) are on the same side of the orbital plane.
You're using her as bait, Master!
Why would we need to fly there? Man made satellites are already in place that map the surface of the planet. There aren't any forests or rivers to block your path, why not just build the equivalent of a Jeep with ten meter tall balloon tires and drive wherever you want to go? I would guess that an engine that puts out sufficient torque to do that would still be more fuel efficient than, say, a rocket, and balloon tires ought to be easier to build than a hundred-meter wingspan...
There aren't that many vertical cliff faces on Mars, are there?
I'm of the 'with gravity that low, make a sailplane-like craft' school ;)
link here
it's a good read and has flash animations so even i could understand it.
this is my sig.
Even with perfect efficiency, you're still off. Assuming you can spin your rotors at 2000/3 RPM and still get enough lift, you've got two problems. First, the tail rotor would have to be MUCH bigger than a regular chopper lest your Marsocopter just pinwheel around when it lifts off. Second, and much more important, you're still missing on the whole lift problem, as helicopters use manipulation of lift to maneuver, and although gravity is lower inertia doesn't change with weight, only with mass. So, even assuming you can get the airframe stable, all you'd have is an airborne crane, because in 1% atmosphere the physics of the rotor collectives (made of any known material) would be impossibly hard to use without wild loss of control. On Earth it's hard enough to keep a helicopter stable. You'd have to give up so much fuel efficiency to maintain flightworthiness (with tapered and/or variable width rotor blades and the massive collective drives necessary to tip each of these big blades, plus the larger engines for the lift and tail rotors) that I can't imagine it would be worth the effort.
Virg
> So whats wrong with retro rockets 1/3 gravity should help here.
Lower gravity doesn't help with retrothrusters. Think mass, not weight. That said, retrorockets would work quite well, but they're very inefficient in terms of vehicle weight and cost and such. Arresting gear (his suggestion is a simple tailhook) is cheaper, less prone to failure and easier to maintain, which is why it's a better choice.
Virg
> Since when is it not safe to use hydrogen? Since someone was
> stupid enough to coat a hydrogen-filled dirigible with thermite?
Um, yeah, right about then. (BFG)
Virg
My vision for a manned Mars flyer always went more toward the idea of an ultralight, in the same vein as the trip down the axis of the vessel in Rendesvous with Rama, since I figured a large span, ultralight airframe was about the only device capable of steering within any safe distance. Thrust is still an issue (props don't work very well in thin air, after all) and the airship is fragile but at least you don't need to be moving at an insane speed to get off the ground, and an ejection from a damaged or out-of-control craft could be affected with a simple jetpack (jump from the craft and use the jetpack to touch down on your feet, ideally).
By the way, MTG refers to the game Magic: the Gathering from Wizards of the Coast. One of the cards in the game (a popular card when it was first printed) was an Ornithopter.
Virg
> Lower gravitational force means you need less force to counteract it.
Since the original discussion was arresting forward motion after landing (this is a plane, so we're not talking about deorbiting), I'm not sure how you feel that a change in gravitation applies.
Virg
Well, if they're used for lift then they're not retrothrusters, now are they (BFG)? That's actually not a bad idea for moving on the surface of any low-grav planet, and jump jets were proposed for Moon vehicles back in the '70s. They are still too expensive in terms of fuel at this point, but for navigating rough terrain without flying (on the Moon aerodynamic flight is, of course, impossible) the designs look very promising. One of the best designs I saw involved a treaded vehicle with jump jets to hop over big obstacles, in much the same vein as the Battletech mechs. That way, you don't need as much fuel but you can get out of (and into) some very tight spots if need be.
Virg