Question Micro Air Vehicle Project

 #1 Viper2000 Nov 03, 2003 06:38 AM

Micro Air Vehicle Project

hello all :)
my name is Matt, and I'm a student at sheffield university (uk). I'm involved in an engineering project to build a micro air vehicle which is defined as a vehicle with a maximum dimension less than 15cm (6"). I'm guessing that the way to go is electric powered, but I must confess that I've never really built anything like this before. My background has been in full scale aviation, and obviously the rules are rather different than at the very low Reynolds numbers you'd find in a micro vehicle. So I thought I'd ask you guys for some advice.

I'm looking for the following;

an existing off the shelf aircraft that's about the right sort of size - if nothing this small exists, then what's the smallest out there?

an idea of where I can get technical data on small rc aircraft. My supervisor wants me to build up a database for my optimisation calculations, and to do that I need things like weight, wing span, wing area, L/D, endurance, and flight speed. Unfortunately I can't seem to find very much data to populate my database at all.

My intention is to build an off the shelf aircraft to gain experience, and then design my own, *hopefully* better aircraft for my project.

Oh and the aircraft has to carry a small payload of around 5-10g. The goal is to get as much range and endurance as possible with the payload. At the moment my calculations seem to suggest a flight speed of around 10m/sec (eventually my supervisor wants this thing to fly outdoors, so it needs to be able to penetrate light winds...).

I know this is a tough one, because my supervisor never lets me off lightly!

Matt

 #2 epilot Nov 03, 2003 07:01 AM

Can't give you a definitive answer. However I can tell you that you will have to "roll your own". AFAIK there are no off the shelf planes in this size. 15 cm is very little so you probably need a something with the largest possible wing area which would be a square. That will give you a wing area of 2.25 dm2. With commercially available equipment you can acheive a 20gram or less AUW (excluding payload). Mind you, that is with equipment that will give you decent range and duration. Add the 10 gram payload and you end up with a wingloading of 13.3 g/dm2 which should work ok. Take a look at this thread for starters - you might just be able to shrink the Drenalyn and make it work.
http://www.rcgroups.com/forums/showt...light=drenalyn

Can't help with the hard facts for the database - I'm more of a "that looks about right" kinda guy.

You could try and contact Matt Keenon who makes MAVs for a living.

Michael

 #3 Mike Taylor Nov 03, 2003 07:38 AM

Try this link for Matt's Black Widow information: http://www.aerovironment.com/area-ai...rv/bwidpap.pdf

 #4 Keennon Nov 03, 2003 02:56 PM

Matt- I've been working on MAVs for quite a few years now, If you can't pull off our AIAA paper from the AeroVironment website, I can send it to you. In that case send me a private message with your email address. I can send you material that has been cleared for public release.
Good luck,
Matt Keennon

 #5 Thatovalguy Nov 03, 2003 07:01 PM

Check this site out

http://www.aeronutz.flyer.co.uk/

and than this one too

http://www.smarttoolsinc.com

 #6 jaeconsult Nov 03, 2003 09:40 PM

Hi

I have been flying electric aircraft exclusively for the last 4yr. You will probably want to go with the rffs-100 system, utilize lithium-polymer batteries. I have seen the skeeter micro plane that uses the rffs-100 and it flys very well. You can get more info at www.slowfly.com on this system. I am assuming that the system needs to be proportional. The rffs-100 system utilizing the actuators is extremely light. Are you wing area limited?? If not consider a biplane or a tandem wing platform utilizing contra rotating inline props similar to the do-335 this will relieve torque problems and allow a larger disk area for better power transfer, of course remembering that more motors requires more availiable power which causes more weight which requires either higher speed or more area. Last but not least, parasitic drag on small aircraft is a killer so keep it to a min. Boy what a balancing act.
Hope this helps

 #7 blswinney7 Nov 04, 2003 04:21 AM

Micro Air Vehicle Project

I took a quick look at the references that others have provided and there is one additional reference that I would like to recommend. It is Radio Control MicroFlight and their URL is:

<http://www.rcmicroflight.com/>

Someone else has already provided the URL to the only other web site that I would recommend in this instance and that is:

<http://www.aeronutz.flyer.co.uk/>

Good luck and God speed on your project. I would appreciate it if you would occasionally inform us of your progress and further information needs.

Bryan Swinney

 #8 Viper2000 Nov 04, 2003 09:58 AM

Thanks a lot for your kind assistance everyone!

I'm particularly interested in amassing as much technical data on existing aircraft as possible, because my supervisor wants me to build a database of existing aircraft for useage in my optimisation calculations.

Therefore I'm especially interested in a breakdown of component weights, some idea of the design load factor of the aircraft, the engine thrust and the cruise speed, so that I can get an idea of the sort of L/Ds that are possible at these low Reynolds numbers.

I'm particularly short on data about the cruise speed of aircraft at a range of weights, which would enable me to calculate a reasonable Cl.

Again thanks a lot for all your help.

Matt

 #9 blswinney7 Nov 04, 2003 12:14 PM

Micro Air Vehicle Project

Viper 2000,

The publication RC MicroFlight has all of their editions on line and has the detailed type of information you are seeking. Your portion of the project does not sound very interesting. As for me, I don't even enjoy building much less data base building, I just like to fly. Your professor is a cruel and thoughtless task master and you may quote me. The lest he could do is vary the work a bit. If my sleep apnea befoged mind were a little clearer, I would think of a few more apropose comments for your professor, . . . but it is not . . . so I won't.

God bless . . .

Bryan Swinney

 #10 Thatovalguy Nov 04, 2003 02:34 PM

Wait till you find out that at these reynolds numbers a Flat plate wing work as well as a curved:eek: try explaining that one to your supervisor.:D

If you search reynolds you might be able to find the thread on the conversation in micro indoor, it was lengthie.;)

As far as all the info and date on most planes in here, which your supervisor is looking for, most are built to a certain perameters and than the looks good method takes over.

Designing usually work out like this..
I know a plane of this size and weight works so lets try this, oops, well lets change that, mmmmm, ok now this........well how about this, OK now it flies well, its a keeper.:D :D :D

 #11 Viper2000 Nov 04, 2003 03:46 PM

yeah that's actually how I wanted to do it; unfortunatly I've got to do a load of optimisation calcs before I'm allowed to build anything! It's a bit of a pain, but I guess that's just the way it goes...

 #12 Jgardner Nov 04, 2003 07:15 PM

As to speed

Did you notice on the smalltools website the performance calculator? It is here

Hope that helps.

 #13 Pook Nov 04, 2003 09:47 PM

Matt,

I was just wondering is the 6" max dimension something you have imposed on your self or has this been set by your supervisor ?

Piers

 #14 Kallikrates Nov 04, 2003 10:40 PM

The definition of a MAV is a plane whos max dimension is 6" or less

NASA was going to publish the research papers for this years anual international competition hosted at Gainesville, but I haven't heard any news. Thats loads of information on the subject that will soon be out there for the public. Most of the wining planes where smaller than the black widow while being a little less efficent. The only limits to our current tech to approaching sub 4inch planes with camera are prop development to fit within the envelope(prop counts) and provide enough thrust while not over tourquing the plane.

6" planes that carried cameras were build 2 years ago with hs50's gws equipment and u80 props for equipment, with whatever latest lithium polymers we could fine.

If it's in your budget this years competition will be held in arizona details still need to ironed out, but we should see alot of <5" planes out there with all the new super light equipment comming out for off the shelf.

 #15 Pook Nov 05, 2003 09:48 AM

This confuses me somewhat.... I have read on a few of the military/govement sites in there press releases that they say a MAV is sub 6" but then this is often not the case.
Up to just a couple of years ago very few of the planes in the MAV competition were sub 6" & for instance AeroVironment's own Hornet & WASP MAV's are well in excess of 6"

Basically what im saying is that while 6" would be a nice size to aim for, It would be a little easier if you could stretch that out a couple more inches. This way you wouldnt have to have the lightest of everything, as I pressume your buget is very limited.

Im in the UK as well Matt and if you want i can point you in the right dirrection for some online shops & some suitable equiptment.

Piers

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