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Old Mar 04, 2012, 08:59 AM
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Joined May 2009
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First FPV feedback wanted

Hi everyone--it's been a long time coming, but I'm finally about ready to start doing some actual testing with my FPV plane. I wanted to ask for any obvious mistakes, suggestions, or other feedback you could give.

The plane is a scratchbuild FPV V3 (Mikeysrc.com). This was my second scratchbuild, and a 14 year old kid did a lot of the work. The quality/precision reflects that I'm not real sure where to make the CG, because we modified the design a little bit. Will (from MikeysRC) told me to do a "glide test", where you run as fast as possible and "feel" if the plane wants to climb or dive. Dive= nose heavy, climb = tail heavy. I dunno about this...I tried it earlier today and it seemed to want to stay pretty straight and level. Maybe I'm right on

The FPV gear is a SAW-upgraded 1.3 GHz receiver from RMRC, an 800 mW 1.3 GHz transmitter ("Sunsky" brand), a SKW and CL antenna (can't remember which goes where). The camera is nothing fancy, it's a no-name security camera from a local (Thailand) security shop. 480 lines, I believe. The screen is a cheap 7" TV tuner I obtained locally--unfortunately it seems to do the dreaded 'blue screen' (actually, it goes black...). The ground station is pretty primitive, basically a "future-board" (corrugated plastic) box mounted around a piece of playwood. I'm planning on attaching that to a bamboo pole that I will drive into the ground.

Transmitter is a 2.4 Spektrum DX8. Reciever is the Spektrum AR8000. I have an old 72 MHz JR laying around that I might eventually switch out, depending on how much range I eventually end up getting.

I did a bunch of twisting of cables, not sure exactly what that's supposed to do, just see that everyone else does it and I hear it somehow eliminates noise? Also randomly threw in some ferrite rings. The wiring is rough--I admit. I'm not really satisfied with the level of clutter on the top wing....but I'm not real sure how to avoid that, while also maintaining distance between noise producers, noise amplifiers, and noise receivers.

Anyway, couldn't have done it without the folks on this forum. Thanks for any tips!
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Old Mar 04, 2012, 04:22 PM
Out of the way, Peck!
United States, AR, Arkadelphia
Joined Mar 2010
148 Posts
Better to have all the wiring and boxes under the wing than on top...top should be as slick as possible. Poke a hole in the wing and mount the Cloverleaf right on top of the wing with the wire running down to the TX. (I have the same Video TX). Probably a good idea to have some (short) coax between the antenna and the TX for stress/ impact relief. CL goes on the plane and SPW on the ground station.

As for the CG, with that wing i dunno. Usually CG is 1/3 of the way back from the leading edge of the wing, but with the way that wing curves back the CG will probably be further back?

I have an Aiptek MPVR+CB camcorder that has video pass-thru between my VRX and my 7" screen, the camcorder prevents the dreaded bluescreen.

I like some of Mikey's designs but (in my opinion) even if that plane was all grey it'd still look strange. But the important thing is how it flies.
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Old Mar 04, 2012, 05:51 PM
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Thanks for the tips Oddmar. I put the electronics on top mainly because it was easier. I suppose that I COULD move them under....arrgh.... On a scale of 1-10, how important do you think that is? I'm really not looking forward to moving all of it!

Thanks for looking....and yes, it's an odd plane, no matter how you slice it!
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Old Mar 04, 2012, 06:11 PM
Out of the way, Peck!
United States, AR, Arkadelphia
Joined Mar 2010
148 Posts
It depends...if it's just a flat wing with no contour or 'body', just a piece of coroplast that you are pushing through the air with brute force...it doesn't matter.

But if it is two pieces of coroplast, the bottom flat and the top arched, as in a 'real' airfoil, and you want it to actually fly for a long time, it's important for the air to flow smoothly and fast across the top of the wing to provide lift.

Plenty of people make simple foam or coroplast winged planes and force them through the air with power, and that's fine if you just want to fly in a gym or maybe in the park. But if you want an FPV platform that will stay up for 20-30 minutes and climb to 1000' AGL, you need a shaped wing with minimal turbulence-inducing junk on the top.

I'm building something similar to this...but my fuselage is lower and tapered in back, with a single boom. http://www.rcgroups.com/forums/showthread.php?t=1034007
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Old Mar 04, 2012, 10:32 PM
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Oddmar, that makes sense. This is a sort of "test plane". Its certainly not very aerodynamic, to say the least! Certainly falls into the brute-force category It will be meant for training some students to fly, with FPV added for fun.

One of these days I'm going to start a 'proper' airplane that's aerodynamic and has an actual airfoil.

Good news for me is that I don't have to re-do the wiring!
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