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My small fpv airplane scratch build - Velos1

#1
Hey all,

I have flown both rc airplanes and quads since last summer but it had always been a dream! :)
It has been a few months since I started reading through the forum and I was impressed.
Seems like there are many enthusiasts like me who enjoy flying and building rc model flying machines
and the knowledge base is priceless for anybody who wants to build his own project.


Flying my bixler in FPV has been lots of fun and I scratch built an even larger platform for FPV that can lift heavy loads and stay up for more than 30minutes on a 3S 3000mAh battery.

I decided I wanted something small and fun rather than big and very stable.
I also wanted a small model that would fit in the back of my car in a small space.

My scratch builds are usually made of styrofoam, because I have a hot wire cnc cutter. Because styrofoam is not very dense, I use dollar-tree foam for control surfaces - mostly stabilizers and rudders.

Everything is held together by hot-glue and barbeque skewers, along with wooden rods for stiffening the wings.

A few specs for my little plane:
- Wingspan: 890mm
- Total length: 700mm
- Total weight including a 3S 1000mAh battery and receiver but without fpv gear: 476g
- Designed to run on 3S 1000mAh as a trainer, or 3S 2200mAh for FPV (needs to fly a lot faster though)
- 3 channels (ailerons/elevator, rudder is optional)
- Using a rewound Turnigy 2625 - circa 2000kV with a 5x5 speedprop
- FrSky 2.4 GHz receiver with diversity and failsafe (just so that I can get my bird back)
- No OSD unfortunately - I accidentally burnt it during trials by mistaking polarity.

The main wing uses an airfoil I designed a few years back for powerkites, modified to be used on an airplane.
Because it is flat-bottomed, the plane does not fly so well inverted and rolls are not very tight.

velos1_2013-03-30_13-32-07_505.jpg



On the first flight I realised that the horizontal stabilizers were a bit too small and as a result it would be a bit unstable. Increasing the surface area made the plane much more controllable. After the first flight I also added winglets to improve tracking and slightly reduce tip stall.

Everything seems to have worked well and this little airplane is all that I could have wished for.
It can fly slow without stalling and the control inputs are very direct. It tracks straight and I have tested
it with gusty winds up to 50km/h without significant problems.

Although I had some problems with my ailerons disconnecting during flight, I have now converted them to
hinged rather than taped and they are rock solid.

This is what it looks like now. Even with all the FPV gear and a 3S 2200mAh battery on it, it barely weighs more than 800g, which I think is quite light for an fpv platform.

velos12013-04-09_12-40-58_790.jpg

This is a video of the test flight during which one of my ailerons collapsed. I also noticed after the flight (and crash in the end) that my video transmitter was putting out a lot of noise without its metal box, causing lockouts in my controls.


I would like to read your ideas, comments and feedback!
 
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