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An UltraLight plane on Mars?



 
 
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  #1  
Old October 31st 03, 08:28 PM
A Canuck
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Default An UltraLight plane on Mars?

If one was to be asked to design an UltraLight that would be able to
fly on Mars, what would have to change?

Would the wingspan have to change significantly?
The atmosphere is thin, but the gravity is less.

Would the propellor size have to change because of the thin atmosphere?
Would a propellor be efficient at all anyway?

Would it be better to use a balloon/blimp vehicle for controlled
exploration rather than an ultralight?

If you needed an emergency parachute for the ultralight, it would need
to be larger than one on earth?

Is there something else that is missing?
A methane powered engine?
  #2  
Old November 1st 03, 04:31 AM
MSu1049321
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Default An UltraLight plane on Mars?

You can try several scientifically reasonable simulations, or make you own,
using the PC and mac versions of X-plane, from Laminar Research. The free
downloadable demo lets you fly for five minutes at a time, and has mars
simulations with realistic grav and atmosphere. The mars planes are rocket
powered, but players have made some of their own verisions available for free
download. or, s I said, you can use the included planemaker utility to
construct and test your own designs.
  #4  
Old November 1st 03, 12:56 PM
Ian Stirling
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Default An UltraLight plane on Mars?

A Canuck wrote:
If one was to be asked to design an UltraLight that would be able to
fly on Mars, what would have to change?


Make it much, much bigger.

Would the wingspan have to change significantly?


It depends.

As the air density is so much lower (around 1% of that on earth) a
standard ultralight moving at the same speed it does on earth will
generate about 1% of the lift.
Or due to the lower gravity, about 3% of the lift needed to keep it
at a stable altitude.
You need to fly about 6 times as fast as on earth in order to push enough
air downwards to generate enough lift to keep up.
So, a typical ultralight with a speed of 25m/s (around 50mph) might
need to fly at 150m/s (300mph).
Of course, you'd need a long prepared strip to take off and land at this
speed.
For a proper "ultralight", landing at a similar sort of speed to one on
earth, you'll need to make the wing area 30 times larger.
Challenging.

Engines are of course another challenge. Propellors work just fine, but
there is no oxygen to burn, so you need to take it with you.
  #5  
Old November 1st 03, 05:50 PM
Henry Spencer
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Default An UltraLight plane on Mars?

In article ,
A Canuck wrote:
If one was to be asked to design an UltraLight that would be able to
fly on Mars, what would have to change?


Mostly, lots bigger wings. (Lighter gravity, yes, but *much* thinner air.)

Possibly a non-airbreathing engine, since a thin CO2 atmosphere isn't good
for much engine-wise. (There are things that will react with it, but the
options are very limited.) Big propeller.

Would a propellor be efficient at all anyway?


Yes, reasonably so, unless you want to try to fly at very high speeds.

Would it be better to use a balloon/blimp vehicle for controlled
exploration rather than an ultralight?


Probably. They're good at different things, but one advantage of a
lighter-than-air vehicle is that it doesn't need a runway. Much of Mars
is pretty rough and rocky, so you couldn't depend on being able to find a
nice long flat spot to land an airplane... especially since the air is so
thin that landing speeds want to be high.

If you needed an emergency parachute for the ultralight, it would need
to be larger than one on earth?


Much. In fact, it's a tricky thing to do at all. Parachute descent
speeds are rather high for reasonably-sized parachutes.

Is there something else that is missing?
A methane powered engine?


Why methane? If you're carrying both fuel and oxidizer, you want things
that are easily made and conveniently stored. LOX plus liquid CO would
probably be the combination of choice if you're willing to handle
cryogenics -- not as energetic as you might like, but easily made using
all-Martian resources. If you don't want cryogenics it gets stickier, but
monopropellant H2O2 or N2O would be an interesting option -- the latter in
particular has the advantage of not containing hydrogen, which is scarce
on Mars.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |
  #6  
Old November 1st 03, 06:15 PM
Charles Buckley
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Default An UltraLight plane on Mars?

A Canuck wrote:
If one was to be asked to design an UltraLight that would be able to
fly on Mars, what would have to change?



A lot.

Would the wingspan have to change significantly?
The atmosphere is thin, but the gravity is less.



The atmosphere tapers off a lot faster than the gravity. Gravity is
about 1/3 Earth's gravity, but the atmosphere is about 1% of Earth's.
The losses do not offset well as you lose lifting capacity far more than
weight to be lifted.

Would the propellor size have to change because of the thin atmosphere?
Would a propellor be efficient at all anyway?


Hmm. Depends on size. There would be a breakpoint that would be very
dependant upon vehicle mass for that equation.

Would it be better to use a balloon/blimp vehicle for controlled
exploration rather than an ultralight?



Definately. hydrogen is a viable lifting gas on Mars and the Martian
atmosphere is actually a lot better in terms of bouyancy. (hydrogen is
about 2g/mole. Earth's atmosphere is about 29g/mole, given a ratio of
about 14.4 to 1 between the gases. Mars has an atmosphere that is about
44g/mole. For a 22 to 1 ratio.).


If you needed an emergency parachute for the ultralight, it would need
to be larger than one on earth?


Yes.

Is there something else that is missing?
A methane powered engine?


methane. carbon monoxide. Electric. Any number of possibilities.

  #8  
Old November 6th 03, 11:54 PM
Robert Conley
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Default An UltraLight plane on Mars?

In X-plane they have a Mars Flight Simulator. Flying on Mars has
following characteristics.

1) You can fly with a large wing span and propulsion that can operate
in an atmosphere with no oxygen (i.e. rocket)

2) You can fly up and down easily.

3) Turning is very very hard and you have to have a lot of room to do
it. This is a combination of the thin atmosphere, lower gravity, and
the fact that inertia is still the same for your craft as it is on
earth.

4) Big long runways it takes forever to take off.

5) Runways with arrestor wires and planes with tail hooks. The safest
way to stop is via a carrier type landing with arrestor wires and
tailhooks. You roll forever on mars.

6) The atmosphere scales differently so it is thinner but you can go
higher than earth.

Rob Conley
  #9  
Old November 10th 03, 01:41 PM
Ken Goodrich
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Default An UltraLight plane on Mars?

Oh? see http://marsairplane.larc.nasa.gov/ or
http://techreports.larc.nasa.gov/ltr...-2003-6578.pdf

Ken G.


"Henry Spencer" wrote in message
...
In article ,
Bruce Hoult wrote:
I don't think a prop will be useful -- you'll need a jet.


NASA's designs for Mars aircraft have all used propellers (although the
engines have typically burned monopropellant hydrazine).
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |




  #10  
Old November 11th 03, 12:07 AM
Henry Spencer
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Default An UltraLight plane on Mars?

In article ,
Ken Goodrich wrote:
NASA's designs for Mars aircraft have all used propellers (although the
engines have typically burned monopropellant hydrazine).


Oh? see http://marsairplane.larc.nasa.gov/ or
http://techreports.larc.nasa.gov/ltr...-2003-6578.pdf


Picky, picky. :-) Yes, I was thinking of the traditional airbreathing
designs, and forgot about ARES, which has quite a short flight duration
and hence can use rocket thrust.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |
 




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