UMX inspired Yak - RC Groups
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Nov 30, 2010, 10:36 PM
Aircraft Designer Guy
AJWoods's Avatar

UMX inspired Yak

Inspired by the new e-flite UMX Extra 300, I decided to make a Yak 55 using the same construction technique and the 4-site electronics.

The planform is as close of an approximation to the extra as I could guess from the stock photos, stretched about an inch to match up with the Yak 55 fuse. I drew up the profiles in SolidWorks and laser cut the parts from 3mm Gediplac.

The foam parts were skinned with 0.35mil painters drop cloth from Home depot. The smallest package they had was 3600 square ft, so I've got enough for a few (thousand) more. The drop cloth is about the same weight as the mylar covering used on the vapors, and presumably the new extra, but it will stretch a bit more before tearing. I attached it to the foam with a dusting of 3m77, and used the skin as a hinge for all the control surfaces.

I used all the carbon and hardware from the 4-site, lengthening the pushrods about an inch. The gear is a bit short, but is good enough for now.

The finished weight came in at 32.3g, with a TP 150 cell, which is almost exactly the same as the extra. If I cut another there are a few places I'd beef up, but I think I could still keep it around 32g.

The plane is awesome to fly. I was really surprised how much better it feels than the 4-site. Rather than just being a micro that can do some 3d, it flies like a standard sized 3d foamy (just in a much smaller space). Minimal coupling, and very crisp all around. The drop in weight is noticeable, and there is reserve power when you need it. If Extra flies similarly Horizon's got a real winner.

Better video, and version 2.0 to come.

Micro 3D Yak (1 min 15 sec)

Last edited by AJWoods; Nov 30, 2010 at 10:38 PM. Reason: added video
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Dec 01, 2010, 09:36 AM
Alien_Tech's Avatar
Nice job Adam! Looks like it flies fantastic!
Dec 01, 2010, 09:50 AM
Paddle faster - I hear banjos!
huckleberg's Avatar
man i am jealous ... wish i had the time and skillz do things like this! flight report/vids?
Dec 01, 2010, 10:50 AM
Registered User
MUTCAKE's Avatar
Great Build,
I know I can make a plane like that....But boy can you fly! .....I wonder.... If I build a plane like this will my skills increase? (Probably not)
I've always wanted to learn to do rolling circles I guess I'd better get a simulator this Christmas to practice. Great Job..
Dec 01, 2010, 11:14 AM
Aircraft Designer Guy
AJWoods's Avatar
Thanks guys. Having a small space plane like this does help keep the thumbs sharp.

Latest blog entry: Star Wars Dogfight
Dec 01, 2010, 11:19 AM
Addicted to 3DHS and EF
3Daddict's Avatar
Really nice job, looks great.
Dec 01, 2010, 01:47 PM
departure from controlled flt
airportdog's Avatar
Well done Adam!

And thanks for sharing the build details. I think you've inspired a lot of us to give it a try.

Dec 01, 2010, 02:09 PM
Storm Runner guy
Slider2732's Avatar
Congrats from here too
Was talking about something similar with my wife yesterday, the way that indoor flight is getting to the point that TV has. Every pixel on the screen can be any colour and anything can be shown, in any way. This sort of model, homebuilt, flying like it does, shows that indoor airspace is becoming the same !

Need good skills for TV and cinema CGI though, as we do for flying like you did in the vid hehe
Dec 01, 2010, 05:30 PM
Registered User
indoor_fr's Avatar
Dec 01, 2010, 06:02 PM
This Calls for a Sexy Party
StewieRC's Avatar
you should make plan or kit and sell it, look like a really nice flyer
Dec 01, 2010, 07:42 PM
Aircraft Designer Guy
AJWoods's Avatar
Thanks guys. No intention to sell them at this point. Once I get some elements of the designed ironed out, I'll probably post the drawings so others can enjoy the plane.

Latest blog entry: Star Wars Dogfight
Dec 01, 2010, 09:18 PM
Fly long and land softly
Jim_Marconnet's Avatar
There is another thread that I've been following in which a Russian pilot builds similar, but larger planes using carbon fibre and a plastic covering:

Not suggesting that you do it, but someday I'd like to see someone build two "identical" airframes. One in foam and plastic like you did, and one like he does his. Then to see how they compare in weight, durability, stiffness, drag, aerobatics, etc.

Dec 02, 2010, 02:29 PM
in persuit of low wing loading
Gordon Johnson's Avatar
Very nice job. It's nice to see more people doing skeleton planes. I think this is catching on as the next thing after milled foam airframes.

Dec 02, 2010, 03:44 PM
Registered User
Petefoss's Avatar
Lot's easier for homebuilt and I bet for mass production a laser cut skeleton covered with film is cheaper than milling.
Dec 02, 2010, 05:22 PM
Registered User
Originally Posted by MIT KID
Thanks guys. No intention to sell them at this point. Once I get some elements of the designed ironed out, I'll probably post the drawings so others can enjoy the plane.

Is there any chance I could get the Solidworks file for this?

Our FIRST robotics team just bought a CNC mill and we don't have any good drawings to test it with. If we actually get everything working, I have an AR6400 brick out of my Sukhoi that needs a home. I'd really like to have a really small plane for a few of the kids on our team to fly at the school before the robotics build season starts.

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