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Old Jul 23, 2005, 10:20 AM
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Joined Jul 2005
7 Posts
Micro air Vehicle propulsion system

Hi,

I am making a micro air vehicle, see the video section on my website
http://www.callisto.si.usherb.ca/~vamudes/

This is the first prototype.
I need to optimize the propulsion system in order to have 30 minutes of autonomy. I have a limited wingspan of 8.5 inches. the airplane currently weights 70g with 11 minutes of autonomy. it will weight approximately 100g for the 30 minutes autonomy.

I plan to use 900mah li-polymer ans GWS edp 50 motor with ep3020 or ep3030 propeller.

What would be the best combo motor/propeller to achieve that?( The plane goes at approx 25mph)

Thanks for any suggestion.

Charles
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Old Jul 25, 2005, 11:30 PM
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motorhead's Avatar
Kansas, USA
Joined Sep 1999
3,888 Posts
You should look at a Brushless motor. Edge RC (http://www.edgerc.com/pcw.htm) has a small Feigao 12x30mm Brushless Motor that would work well. On a 1200 pack I have seen his pocket combat wing do about 80mph. THrottled back to about 40 it will fly for 30 min easy. Tell him what you want and he should be able to recommend something.
Mike
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Old Jul 26, 2005, 05:17 AM
can you land on that ?
Scottish Highlands
Joined Jan 2005
3,248 Posts
Charles are you entering the MAV05 event? If so where are you based. Any Brits fancy the trip? I have contacts in Garmisch-Partenkirchen.
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Old Jul 29, 2005, 03:55 PM
Who needs a pilot??
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Alexandria, VA
Joined Jul 2002
1,161 Posts
Smaller servos and a lighter weight receiver could be a good trade off for more motor run time and lower weight. Check out some of the Wes-Tek servos and the SkyHook & Rigging receivers. I bet you can trim 1/2 the weight of the radio gear in exchange for runtime.

Brushless is the way to go. Aside from the commercial mini brushless motors like the Feigao, you can get good efficiency with a CD ROM conversion kit, and super light weight too!

Switching to a Depron and carbon wing is lighter and stronger than the blue foam. Grey surf-board foam is also less dense than the blue foam.

You can increase airframe efficiency by moving getting rid of the rubber bands and just gluing your wing on.

The indoor aircraft forum would be a great place to search for extremely lightweight systems. Those guys live for making smaller and lighter weight components. I'm sure they could also recommend a bunch of small motor choices.

G'luck! Post some pictures up here from time to time :-)

Dan
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Old Jul 29, 2005, 05:59 PM
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Brunswick GA
Joined Jul 2005
14 Posts
this is just a sidenote....

We have a Micro UAV (actually a few) project here at UMD. The one I'd like to tell you about is going to use the free wing concept. I have flown some of the Micro UAVs here and they are really kinda unstable in roll - when I say unstable I really mean to say that wing gusts knock the little airplane around pretty good and all too quickly (me - the pilot) will begin to induce the oscillation due to over corrections.

So we are trying out the free wing concept. Just today I saw some footage and the experimental setup for the little aircraft. It's pretty sweet! I kinda disconnected myself from the Micro UAV project since I am busy building my over 40 pound aircraft. But I guess pretty soon they are going to ask me to fly their baby.

Evandro
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Old Jul 29, 2005, 06:10 PM
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Brunswick GA
Joined Jul 2005
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hey DAN...where do you get grey surfboard foam?
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Old Jul 30, 2005, 07:13 PM
Who needs a pilot??
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Alexandria, VA
Joined Jul 2002
1,161 Posts
Um, I used some scraps from work :-)

I'm not sure if this grey foam is the same as SPYDER foam that Dr Drela likes (of Apogee and Supra fame), but I do believe it is also called surfboard foam. On the Allegro-lite yahoogroup, there was lots and lots of discussion about different types of foam.

So basically I don't know what I've used, but it was grey and less dense than the blue foam. Maybe the yahoogroup will turn up some new information...

Dan
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Old Jul 31, 2005, 01:05 AM
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United States, MD, La Plata
Joined Nov 2004
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The grey foam is known as Dow Greyboard, go figure! It has a density of 1.5 lb/sqft and is a great compromise between the white foam (1lb nominal) and blue foam (2lb) plus hot wires and sands great. SPYDER foam is a different animal.

Chris
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