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Monday, April 23, 2007

Flap Flap ... Times Back



So, ppl ... wonder where i had vanished all this time, been on some very distant time travel into the depths of future. Nah. busy with IITJEE. well tats gone so now i can do some thing closer to my heart. This is what i have been working on.

ORNITHOPTERS

Seems a very far fetched name. But wat lies within is even more weird. Ornithopter as d name suggests is 'flight like birds'. flapping wings. no propellers. The key difference between an ornithopter and an airplane is that the driving airfoils move up and down instead of rotating. For both the airplane and the ornithopter, most of the lift results from forward motion through the air. In the ornithopter, lift is produced by the flapping wings, often in conjunction with some additional fixed wings. Birds likewise use their body and tail as a fixed lifting surface.

Why Ornithopter ?
My sudden intrest in ornithopters can be attributed to the recent air mishaps- crashes. i was very upset. the current air plane designs are over a century old. fixed wings. high forward thrust, some thing new is required. Ornithopters are better in following ways:
  1. Very high maneuverability
  2. low noise
  3. high lift
  4. good fuel efficiency
Ornithopter isnt a new concept. the first ornithopter was built in early 1900s !! manned flights on ornithopters hav also been achieved. but considerable work needs to be done before u and i can ride one.
Now wat am i working on? am on a fold wing type model which will have a very strong downstroke, enabling it to 'climb'. i will write the details one i have made a successful model. But there is one problem. This isnt a basic science topic and hence i cant take it up in KVPY program. :(

Well then, i think 3d matrices will be good enough for the summer project ...
waiting for ur responses (and refueling my time machine)
TiMe

23 comments:

Lagnajeet_Das said...

Hey good! U have posted on a topic of my interest..

Well Ornithopters are a good substitute for the fixed wing air crafts. The main advantage is that their flapping wings provide both lift and thrust. But some mechanical energy is still required to flap the wings.Well where does that come from? U again require an engine for that! and the whole thing again returns to the same point as the fixed winged-aircrafts : i.e. the need fr Engines!

Well the ornithopters can be better used for military operations, they can be used for stealthy reconnaissance and surveillance without letting the enemy to know about them due their resemblance to birds!

Arun Chaganty said...

Hmm, I may seem orthodox, but I'm wondering how these ornithopters (I've kept track of them. Leonardo Davinci made a model (or two) using this design right?) will create that much thrust. The way most birds work is because they are so light, they can get pushed into the air via updrafts. A lot of their movement is via the wind. However, the amount of area required to lift a human being would be huge. For this reason, I think that they may only be feasible in say unmanned flights, weather missions, other lightweight operations.

Also, to flap is to push against air perpendicularly, while the glide is just to push against drag (which will be there in flapping as well. Clearly, more energy is required in pushing perpendicularly, than just cutting the air stream.

And at last, I don't see at all why this isn't qualified for research work. I think that it is an excellent field, and entirely within the fields of science. Besides, if your lucky, you could merge a bit of bio into it, and observe natural flight patterns to make it more efficient.

saurya_time_travel said...

Ok now let me answer all ur questions ...
@lagnajet, everything requires an engine, to convert chemical or electrical energy to mechanical. but the advantage that i c in ornithopters is the compact size. i mean with a powerful engine(high power to weight ratio) u can easily make what we may call a 'ornithopter bakpack' - strap it on and lift off.

@arun,
about the size of the wings, it is just a matter of the engine power and flapping rate. smaller wings require faster flapping (eg - dragonflies)

about the lift thing let me get to the fundamentals. air planes depend only on Bernoulis principle for their lift - they move fast, air flows faster over the wing than under it, creating a preasure difference. this causes the lift, larger the area of the wing greater is the lift. (F = PA)but tats not the case with ornithopters, they use the whole of their power to form a lift, balancing the weight just like a helicopter. so does nt depend on wing area for lift. Surely the speed of an ornithopter will be less than an airplane.

obiwankenoby said...
This comment has been removed by the author.
obiwankenoby said...

nice to see u back
ur articles are fun
so is aviation in particular
but ornithopers do feel crude ,forgive the expression, but well i hav got some points lined up
1.high power to weight ratio is the key-wat u said-and THAT cannot be used for commercial flights no.militarty planes can use a combination though-go to the site using bernoulli and then switch to ornithap-ping blades.
2.individual backpacks are an interesting addition to the thoughtbug-flappy wings strapped under your arms but u can get hurt in the process.
but a thread of thinkstink-remember the snitch of hp movies-flexible, limited amplitude,and and high frequency standing wave resonating throughout.
the rigidity of the wings decrease with the spread and the amplitude increases along.
ireally like it but point out the flaws saurya and others.
may b we hav got a patent in the making.lol!

saurya_time_travel said...

@obiwankenoby,
we surely hav a patent in the making. the snich is exactly wat i hav been thinking of. high frq, low amplitude. and by the way, ornithopter backpacks may be dangerous but they r a lot safer than conventional (si-fi) jetpacks. Or even a rotor on top of ur head. lol. just think of it.

ornithopters r crude. they r in the process of research. and u got the power to wt ration thing all mixed up. suppose a 50kg engine can provide 100KW power (and hence carry say 5 people appart from itself) is better than 50kg one producing say 60KW, which can barely carry itself.

I say ornithopters will be the future of commercial flights too.

obiwankenoby said...

arun gives me an idea -
start a da vinci fan club or hav a special section on da vinci and his creation
@time-well i hav been thinking to say this for a long time-can you mail me a version of your 'paper' on time machine or post it here-the one u presented in the summer camp.i am afraid i didnt quite catch it.
with ur commercial flights concept though i dont agree -its too slow,too costly and too manuevorable.

Arun Chaganty said...

I tend to support obiwan (use the force I say). But I was just thinking about it anyway, and I've thought this:

-> The wings must be flexible, and the flex of it must also be controlled. By cupping the wind during the down stroke you will gain the maximum push, and by making the upstroke, more of a side pull stroke, you'll reduce the down push there. My thoughts are that its stroke should be similar to that of a swimmer (or a bird, but that was a bit obvious right ;))
-> A also agree with the low amplitude, high frequency
-> The design must be super super light, while still encompassing the most surface area to take advantages of upcurrents.
-> The system must be designed for uses that don't mind sudden updrafts.

I have no idea how you can control the flex, but I'm sure there are materials that are electrosensitive (I've heard about them somewhere). I'm pretty sure that you'd have thought of all of these points, but I'm just putting them out there.

saurya_time_travel said...

@obi,
i will post tat very soon aft 29th.

and arun,
i havnt heard bout electrosensitive materials, but my model uses simple mechanical methods to create d fold system. i will write in details after 29th ...

obiwankenoby said...

i just hit into another thread of thought- probably high frequency wave wont do-probably.
because they cannot create the thrust neccesary- and also because the thrust gainerd during downward motion of the flappers will be nullified by the upward swipe.
get it??
dont think of valves though- they r too heavy.

Arun Chaganty said...

@ obiwan: Well, that was what I was talking about.

saurya_time_travel said...

@ obi,
hats off. u r absolutely rite. the down stroke should be stronger than the up stroke. that is what i am working on. valves will certainly be heavy, but look how cool nature is. Birds fold their wings during the upstroke to reduce the effective air resistance area. Thus weakening the up stroke. hence what i am making is a fold wing type ornithopter.

obiwankenoby said...

but fold wings say no to high frequency - and that wud have been a lovely one.

Arun Chaganty said...

I agree with Obi here, the folding bit would really reduce your frequency. But...

Suppose you try long slow downbeats, followed by folding upbeat? This would be really like how nature does it ;) But for take off, I don't think this is sufficient. Whereas for gliding, and staying aloft, it should be, provided you frame is light enough.

saurya_time_travel said...

u r rite. high freq flapping disallows folding of the wings. insects that flay with rapid wing flapping dont fold their wings.
and about the take off, ne bright ideas?
look at this site,
www.ornithopters.org

saurya_time_travel said...

oops sori,
its
www.ornithopter.org

Arun Chaganty said...

Well, some birds strokes is not up-down.

It's more like down, back and around, down...

Like an inverted D == (|

Another is the bring the wing down flat, and on the upstroke, angle it, so that it cuts the wind. I'm liking this idea very very much.

I can't think of anything for take off. It basically needs a lot of thrust, and a very fast movement. Take off is a very taxing maneuver. Perhaps the same arrangement, only done with more force and speed?

P.S. Nice linkey.

saurya_time_travel said...

@ arun!
thats what i was doing. make the wing cut air during the upstroke. and brng it down hard ad flat.
and about the thrust i think we have to take help of 'lift off thrusters' like those on air craft carriers. well of course we can use rokets but u kno ...lol...i wont risk my life in sucha thing ...
y dont u ppl try bulding one... see the web page i gave u ...

obiwankenoby said...

i'd say that use helirotors for take off.

saurya_time_travel said...

good idea but it cud interfer wid d flapping mechanism...

Arun Chaganty said...

I think adding helirotors just for liftoff would be overkill.

obiwankenoby said...

yes it wud- but a working MODEL might be a fly without that.
well u definitely cannot add
'lift off thrusters' to the ensemble as it has to be light and compact as well.
when u can come out with a working prototype will be a different game.
so, got other ideas??

Just David said...

High! found you by googling lifting body ornithopter. I am not an aviator or engineer, but a daydreamer who has devoted much time to this. y'all are the first ive heard suggest folding wings, which i agree with, and also low freq. as low as possible keeps structural stresses close to static. folding wings also help with this. about takeoff power: how bout storing some compressed air in a plastic tank for this purpose. could be recharged in flight by slowing your descent. also usable for emergency power ie- momentary vertical climbs to avoid powerlines, buildings, etc. these ideas naturally play out of considering my body as the only feasable engine. think this way-- a 300 sq ft hang glider loses 1ft altitude for 10 ft forward flight. all that is necessary is to make up this loss. ideally, it should feel like carrying a 50 lb backpack up a wheelchair ramp. don't give up, and look out for bullets