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        Discussion UMX inspired Yak

#1 AJWoods Nov 30, 2010 09:36 PM

UMX inspired Yak
5 Attachment(s)
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:eek:, 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)


#2 Alien_Tech Dec 01, 2010 08:36 AM

Nice job Adam! Looks like it flies fantastic!

#3 huckleberg Dec 01, 2010 08:50 AM

man i am jealous ... wish i had the time and skillz do things like this! flight report/vids?

#4 MUTCAKE Dec 01, 2010 09:50 AM

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:p)
I've always wanted to learn to do rolling circles I guess I'd better get a simulator this Christmas to practice. Great Job..

#5 AJWoods Dec 01, 2010 10:14 AM

Thanks guys. Having a small space plane like this does help keep the thumbs sharp.


#6 3Daddict Dec 01, 2010 10:19 AM

Really nice job, looks great.

#7 airportdog Dec 01, 2010 12:47 PM

Well done Adam!

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


#8 Slider2732 Dec 01, 2010 01:09 PM

Congrats from here too :D
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

#9 indoor_fr Dec 01, 2010 04:30 PM


#10 StewieRC Dec 01, 2010 05:02 PM

you should make plan or kit and sell it, look like a really nice flyer

#11 AJWoods Dec 01, 2010 06:42 PM

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.


#12 Jim_Marconnet Dec 01, 2010 08:18 PM

1 Attachment(s)
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: http://www.rcgroups.com/forums/showthread.php?t=1158259

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.


#13 Gordon Johnson Dec 02, 2010 01:29 PM

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.


#14 Petefoss Dec 02, 2010 02:44 PM

Lot's easier for homebuilt and I bet for mass production a laser cut skeleton covered with film is cheaper than milling.

#15 Mad Scientist Dec 02, 2010 04:22 PM


Originally Posted by MIT KID (Post 16703561)
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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