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Old Aug 15, 2005, 10:36 AM
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ok, i guess epilot has a point- time to build a airframe for the $2 bit car i picked up.

great picture, eh?

beano

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Old Aug 15, 2005, 10:57 AM
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What IS that, an RC wheelchair?
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Old Aug 15, 2005, 02:38 PM
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Hi all,

I just wondered whether you have seen this old thread already:
http://www.rcgroups.com/forums/showthread.php?t=165593. It contains some comments from Matt Keenon.

It also contains a picture of my Micro Drenalyn, which (at 8" wingspan) is as close as I have gotten near to a MAV up to now.

Regards, Jochen
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Old Aug 15, 2005, 04:52 PM
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That old thread was one of the ones that first got me interested in MAVs. I build a depron chuck glider of the little "trochoid" design that mlbco posted. After I played with the relative angle of the two surfaces, it flew rather well as I recall. I might still have it... behind the sofa or somewhere.

Jochen,
Neat little Micro Drenalyn. Is it a flat plate or do you have a little camber and reflex? Are those oval-shaped actuators I see? Looks like you mass balanced the elevons too. Nice job. Couldn't get the video link to work, maybe its outdated.

Mark
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Old Aug 15, 2005, 05:12 PM
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I am surprised that there has not been more talk of coax drives or twins with contra rotating props. It would seem the obvious solution to cancel out prop torque which can be an issue on short span models like MAVs. Twin steer might even have is place here if implemented with some proper mixing.

While I find the topic interesting, I think that there is a lack of focus. One part of the discussion is centered on foam plate bit models; the other is centered on fancy applications, radar signature etc. Surely the aim should be to build a well flying model first? Someone already suggested agreeing on a specific payload. That would make sense. With a payload carrying capability you can carry whatever takes your fancy.

A design not to be overlooked is Petter Murrens Proxflyer. It has a lot going for it in terms of stability.

It would be good with some more cooperation between experienced modellers and Universities. Whilst a lot of good ideas are often incorporated into some of the designs from the Uni teams, the models themselves are often badly built and overweight - at least some of the ones I have seen posted here. It seems that they have the theoretical knowledge but lack some common modelling skills. I truly believe that hobbyists can contribute a lot more to science if the universities would work with them.

Your thoughts?

Michael
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Old Aug 15, 2005, 05:33 PM
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Mark,

it is a scaled down Drenalyn including the reflexed airfoil and the boxlike fuselage. Yes the actuators are rectangular, see the picture (from another plane which was my first micro rc plane).

It is crucial to balance the elevons to keep the reflex in the actuator's neutral state. That little dot is a bit of lead (yes, really). Today I would prefer magnetic centering. The elevons might actually be a little big.

I have uploaded the video to my new homepage, it is here now.

Following Michael's suggestions, at least this flies, so it might be a starting point for improvements (smaller, lighter, faster, ...).

Regards, Jochen
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Old Aug 15, 2005, 06:13 PM
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ok, michael is really right on this one... so the main issues are,

1. contra-rotating props versus single prop.
2. what payload to agree on?
3. what design to use?
4. what about helis?

i am thinking, for me, a ifo-like single prop plane with ailerons and bomb drop... i think i can do it with a single bit rx- should be intresting at the very least(ok, and funny too). my thing with helis is shorter runtime, slower forward speed. i dont know, i need to sleep on my seperate ideas .

beano
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Old Aug 15, 2005, 06:39 PM
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An Idea...

Something that I have been meaning to try came back to mind...

The BladeRunner conversions are quite popular...rather than take the entire thing apart, turn it 90 degrees, cut the boom off and give it wings. It is basically a contra-rotating prop and if you have a BR, you know it has quite a bit of thrust. Not a fully baked idea but you have the BR motors, gearset, rx and battery already there...just rearrange it a bit. Probably would have to use smaller props to prevent collision and to scale down a bit...not sure what size wings you would want on this thing. It would be interesting to see how variable speed on the rotor could control direction. Maybe get really creative and make it into one of those box-kite like planes? Just more random thoughts.
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Old Aug 15, 2005, 07:00 PM
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I think this thread is beyond building a well Built flying model that's a given…or maybe its not
Does it really need to fly…..Or just have enough power and the right control surfaces?
Cruise missiles, and jadams comes to mind
Simple test build anything then go fly it in a 5 to 10 mile a hour wind, In Rain you will understand where the weight factor comes in....How about ground Skimming will a little blade of grass or branch send your model spinning out of control

All these factors need’s to be looked at and built into the design
Unless your trying to build a indoor micro Mav and there are ton’s of Design in these threads and the foamy threads that Can be used… The A frame Flyer comes to mind it could be Tweak for out doors..
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Old Aug 15, 2005, 07:47 PM
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tskunka, you could be onto something- having contra-rotating props like the bladerunners, for forwards flight.. then being able to go into a hover- that would be very nice for taking videos. but, it would be hard to cut down the props, then add extra weight..

beano
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Old Aug 15, 2005, 08:49 PM
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the BR would be nice for its stability, but if anyone has a BR and has tried to fly it outside, they know its a bad idea. any wind that is blowing faster than the BRs fastest forward speed (less than 3mph?) will give some serious rotor clashing, and then the inevitible crash. perhaps if there was a way to control the amount of see-saw motion the rotor hubs have, that problem could be over come. perhaps that could cure the slow forward speed of the BR as well (but could also diminish the BR's inherent stability).

nick
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Old Aug 15, 2005, 09:25 PM
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Did some glider test today my Mav Glides real will needs lot of speed to fly in the right Nose up position… Next will be the fan power test I’m sure I will have to go to Brushless for the molded carbon fiber version but will use a 7mm ss for power flight test
Here a few Pics of my very simple but effective Trust vectoring the idea is to give me maximum lift thrust and stoping power when needed SVTOL

Aerogel
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Old Aug 15, 2005, 11:45 PM
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Aerogel,

That's one innovative design you have there. I hope the SVTOL works out. Will the deflected thrust cause the plane to pitch over? How did you decide to use the shape of the lower wing surface?

Mark
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Old Aug 16, 2005, 12:02 AM
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Mark
Couple of things came into mind lifting bodies, skid plate, and protection for ever thing in side of the wings..
As for the deflected thrust Im sure it will I might add a front one to.. I could have Built some vent’s but I did not want to get to technical with this one simple build
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Old Aug 16, 2005, 04:07 AM
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Nick, I was not referring to the BR - it is basically a toy. That is why I said Proxflyer and not BR. The concept has its merits but would need to be explored further.

Aerogel has a point - some tasks could probably be carried out better by other types of craft.

Yesteryears there were the PAA payload events. Maybe a starting point would be to make a micro payload competition. Go with the 6" span and fixed wing only, then build a model that can carry a 2x2x2cm cube weighing 20 grams.

Michael

PS: I'm semi-convinced that if the military finally come up with a MAV it will be something ridiculously expensive high tech gadget instead of something low-tech that could be made by the thousands.
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