Author Topic: Ornicopter for Martian Air Travel  (Read 15165 times)

Offline sanman

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Ornicopter for Martian Air Travel
« on: 06/05/2011 05:50 pm »
As we know, the Martian atmosphere is very thin (1% Earth atm at mean ground level). It's therefore very difficult to achieve useful lift from that atmosphere in a way that would achieve practical air travel on Mars.

I remember once reading that NASA was researching flapping wings as a future mode of transportation for Mars probes, because of the non-linear relationship between the work required to flap wings and the lifting force generated by the resulting vortices. So in thinner air, it's easier to flap your wings, but you still get better lift from the vortices produced by your wing-flapping.

With that in mind, consider the early research being done on the Ornicopter (a machine that flaps its rotor wings up and down, even while they move in a circular rotation). Note that the ornicopter is torque-free, and therefore does not require any counter-torque force, either thru counter-rotating rotors or thru a tail-boom rotor.



http://www.rcgroups.com/forums/showthread.php?t=199182

http://www.helis.com/howflies/rotopter.php

Could this be a way to achieve air travel on Mars?

I'm wondering if this could even be used as a re-entry/landing mechanism, for controlled landing of spacecraft.

Offline mmeijeri

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Re: Ornicopter for Martian Air Travel
« Reply #1 on: 06/05/2011 05:54 pm »
I read some NASA papers about this a while back and the conclusion was that this might be barely possible for small cargo payloads, but not for manned transport.
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Offline sanman

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Re: Ornicopter for Martian Air Travel
« Reply #2 on: 06/05/2011 06:06 pm »
Hmm, well how small is "small"?

Perhaps it would be a question of being able to scale up performance through higher-strength materials and higher-frequency operating speeds, as well as increasing the blade/wing-area and the amplitude of the flapping oscillation, since this affects how much lift you create.

Since the ornicopter concept is being researched for useful applications here on Earth, perhaps we will have a better idea later on, once the technology matures.


Offline mmeijeri

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Re: Ornicopter for Martian Air Travel
« Reply #3 on: 06/05/2011 06:14 pm »
Wait a minute, now that I think of it these papers were about using rotors, not flapping wings. Even small payloads would then have required huge rotors. But maybe flapping wings would work, I have no idea.
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Offline sanman

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Re: Ornicopter for Martian Air Travel
« Reply #4 on: 06/05/2011 06:22 pm »
Here - maybe this image will help to clarify the type of motion we're talking about:


Offline RobLynn

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Re: Ornicopter for Martian Air Travel
« Reply #5 on: 06/05/2011 06:34 pm »
A better alternative is to use a large lightweight kite similar to those used in kitesurfing.   The entire skin is in tension - so they are easily scaled to enormous sizes (even 10000mē+).

With weight as low as 60g/mē we can fly with incredibly low dynamic pressures (about 1m/s winds on earth, so about 6m/s on mars (1% earth density but 38% earth gravity), and can achieve L/D of about 10 without too much trouble, implying a power to weight requirement of only about 2W/kg for the entire craft.

Using such specs means we can support a 1 tonne payload with a 1 tonne 16000mē canopy using about 4kW of power - within the realm of the possible with batteries + solar panels or nuclear power.

A clever trick is to then use oscillating winch propulsion - the payload is suspended on a line far beneath the kite and rapidly accelerates towards the kite by winching in line thereby accelerating the kite.  The payload then goes into freefall paying the line out and the inertia of the kite leads to it swooping upwards until it has almost halted, at which point the winch pulls in again - repeat etc.  Allows propulsion without propellor in a system scalable to massive size, easily tested on earth. (Disclaimer - my brother and father are two of the world's premier kite designers)
« Last Edit: 06/05/2011 06:44 pm by RobLynn »
The glass is neither half full nor half empty, it's just twice as big as it needs to be.

Offline sanman

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Re: Ornicopter for Martian Air Travel
« Reply #6 on: 06/05/2011 07:06 pm »
I dunno - that sounds rather unwieldy to me. I can't picture something like that even being used here on Earth, let alone on Mars. I can picture the ornicopter approach being used here on Earth, and technologically maturing here, before being used on Mars later on. Perhaps it could first be developed for specialized use in high mountain environments, where the air is thinner and the winds/turbulence more treacherous.

Once the ornicopter technology proves itself there, then increasingly high-performance versions could be developed, with an eventual eye to achieving the performance required for Mars. Imagine in the intermediate stages of development, that you could have ornicopters capable of traveling upto large high-altitude platforms floating in the upper atmosphere at Mars-like atmospheric densities.

Offline sanman

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Re: Ornicopter for Martian Air Travel
« Reply #7 on: 06/06/2011 02:57 pm »
Another thing I want to mention, is that with an ornicopter you don't need a complicated motor to drive it - all you need is a linear oscillating motor, which can either be electric or just linear pistons.

You don't need any kind of cam-shaft to convert the linear piston motion into shaft power, because the ornicopter only requires linear oscillating power to drive its flapping motion (the rotation of the blades is just a by-product of the flapping, requiring no torque)

This would make for a more lightweight, simplified, and more reliable motor.

It also makes me wonder whether the ornicopter approach might not even be useful for re-entry vehicles, for controlled landing purposes, and even in lieu of drag chutes to slow re-entry. It's easier to flap in the thinner, higher upper atmosphere, but I wonder how well flapping works in an oncoming supersonic flowstream? Can anyone hazard a guess?

Here's an interesting paper to check out(PDF):

http://www.icas.org/ICAS_ARCHIVE_CD1998-2010/ICAS2004/PAPERS/382.PDF
« Last Edit: 06/06/2011 03:37 pm by sanman »

Offline Caid

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Re: Ornicopter for Martian Air Travel
« Reply #8 on: 06/08/2011 05:18 am »

Quote
SmartBird is an ultralight but powerful flight model with excellent aerodynamic qualities and extreme agility. With SmartBird, Festo has succeeded in deciphering the flight of birds - one of the oldest dreams of humankind.

This bionic technology-bearer, which is inspired by the herring gull, can start, fly and land autonomously -- with no additional drive mechanism. Its wings not only beat up and down, but also twist at specific angles. This is made possible by an active articulated torsional drive unit, which in combination with a complex control system attains an unprecedented level of efficiency in flight operation. Festo has thus succeeded for the first time in creating an energy-efficient technical adaptation of this model from nature.


http://www.youtube.com/v/nnR8fDW3Ilo?version=3&hl=de_DE&rel=0
« Last Edit: 06/08/2011 05:23 am by Caid »

Offline MP99

Re: Ornicopter for Martian Air Travel
« Reply #9 on: 06/08/2011 07:14 am »
It also makes me wonder whether the ornicopter approach might not even be useful for re-entry vehicles, for controlled landing purposes, and even in lieu of drag chutes to slow re-entry. It's easier to flap in the thinner, higher upper atmosphere, but I wonder how well flapping works in an oncoming supersonic flowstream? Can anyone hazard a guess?

Have you seen ROTON / Rotary Rocket:-

http://en.wikipedia.org/wiki/Rotary_Rocket

cheers, Martin

Offline sanman

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Re: Ornicopter for Martian Air Travel
« Reply #10 on: 06/08/2011 02:03 pm »
Yeah, Rotary Rocket's Roton was exactly what made me consider the ornicopter for re-entry purposes. After all, flapping works better in thinner air, producing more lift relative to the work required. Perhaps it might be a more efficient alternative to other re-entry mechanisms. But a supersonic flowstream is a particular case which might be worth explicitly modeling.


Offline JohnFornaro

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Re: Ornicopter for Martian Air Travel
« Reply #11 on: 06/08/2011 03:24 pm »
Quote from: Rob Lynn
A clever trick is to then use oscillating winch propulsion ...

I had not yet heard of that idea.  I would reduce the size of that kite tho, by reducing the payload to 10 or 20 pounds.  One of the things that's really needed on Mars is detailed photographic topography of hi resolution, to start mapping the planet.  It's a mite early to decide where I want to site my ranch, but it's not too early to find sites of great visual interest, which would help with the PR campaign here on the home planet.  Color me bored, but there's only so many rocks that I wanna look at, no matter how "cute" their names may be.

Further, a careful consideration of the instrumentation might stress the methane cycle and the perchlorate cycle, since these are of great scientific interest.  Such a craft could "float" above an area for detailed readings over a longer time span.

If you're only a short distance above the surface, in what is often a very clear atmosphere, I wonder at the resolution the cameras would have.  Could you definitively photograph a pie plate sized piece of lichen? A penny sized "bug"?  A "fountain" of melted water?  There could be a lot of sudden funding if it were to be photographed.

In any case, the kite should also "be" the PV panel, if it can so be arranged, and the data could be transmitted to an orbiting relay station, then back to Earth.  It should also be "drivable", to avoide sandstorms.

Also, I always thought it was an ornithopter.
Sometimes I just flat out don't get it.

Offline Mark S

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Re: Ornicopter for Martian Air Travel
« Reply #12 on: 06/08/2011 04:43 pm »
Also, I always thought it was an ornithopter.

Yeah, me too at first. Just watch the OP's video, it's really quite clever and innovative. I don't really see how it could be useful for re-entry, though.

Offline sanman

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Re: Ornicopter for Martian Air Travel
« Reply #13 on: 06/11/2011 06:46 am »
Ornithopter is a machine that functions just like a bird, flapping its wings to achieve forward motion.

Ornicopter is when you take that flapping concept, and do it in a circular rotational pattern, like a helicopter.

Well, what made me think of it for re-entry is that helicopter-style rotors have been considered for re-entry, and meanwhile the ornicopter approach works better for smaller rotor diameters and thinner air.

Some people have noted that wing-flapping generates vortices, and that each flap motion is able to push off the vortices generated by the previous flap motion, for better lift.
As a matter of fact, if you have a bunch of birds flying in a V-formation, then these flapping birds can push off the vortices from the birds flapping in front of them. I guess that's one reason why they try to fly in V-formation, huh? Because it's easier and more efficient for them.

So the more you push off these vortices, the better.

So I was thinking - what if you're actually rushing towards those very vortices you produce with your flapping?
How would that happen? Well, suppose you've got flapping wings on your space capsule, with each downward wing-flapping generating vortices which also travel downward. But if your space capsule is falling downward, then it's moving toward those vortices that have been created. So you have more opportunity to push off them.

And if you're doing this in the higher thinner atmosphere, then it's also easier to flap. Also remember that flapping is easier for smaller-diameter rotors, which is consistent with the idea of a space capsule that is light and compact.

Offline JohnFornaro

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Re: Ornicopter for Martian Air Travel
« Reply #14 on: 06/11/2011 04:26 pm »
Ornithopter is a machine that functions just like a bird, flapping its wings to achieve forward motion.

Ornicopter is when you take that flapping concept, and do it in a circular rotational pattern, like a helicopter.

Right.  Uhhhh.... I knew that?

You're right about birds in v-formation; it is an energy saving flight behavior adaption.

But the thinner atmo requires the rotor area to be larger, not smaller.  What mass is being considered here?
Sometimes I just flat out don't get it.

Offline sanman

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Re: Ornicopter for Martian Air Travel
« Reply #15 on: 06/11/2011 06:06 pm »
With rotors in general, obviously the larger the rotor disc area, the more lift.

However I'm pointing out that flapping your rotors up and down gives you an extra degree of freedom here, through the frequency and amplitude of that flapping. For a given rotor disc area, you can increase your lift by flapping faster and with greater amplitude. However there are the added structural loads on the rotor to consider, due to the flapping. Clearly those loads diminish as the rotor disc size/diameter decreases.


Offline JohnFornaro

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Re: Ornicopter for Martian Air Travel
« Reply #16 on: 06/12/2011 01:24 pm »
Quote from: sanman
With rotors in general, obviously the larger the rotor disc area, the more lift. ... Clearly those loads diminish as the rotor disc size/diameter decreases.

Obviously and clearly indeed.  Payload mass is the one of the utilitarian considerations which would affect the added structural loads on the rotor.
 
My question may not have been well worded.  What mass is being considered here?
Sometimes I just flat out don't get it.

Offline sanman

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Re: Ornicopter for Martian Air Travel
« Reply #17 on: 06/13/2011 02:02 pm »
I guess I was thinking about something the size of a small space capsule, or perhaps even smaller. For large-sized re-entry vehicles, then the flapping loads are going to be too high.


Offline JohnFornaro

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Re: Ornicopter for Martian Air Travel
« Reply #18 on: 06/13/2011 05:03 pm »
Now we're talking.  If it's a 1000kg capsule, it could carry a fair amount of gear as a part of that 1000kg.  Are you suggesting that the ornicopter arrangement could effect re-entry, and this device could fly around and perform it's mission?  What would the diameter of the rotors be?
Sometimes I just flat out don't get it.

Offline sanman

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Re: Ornicopter for Martian Air Travel
« Reply #19 on: 06/14/2011 04:02 am »
I dunno - let's say under 30 ft

That should be able to handle 1000kg

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