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DTFB - Mini drak 2020-11-13

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#1
Slick1855 submitted a new resource:

DTFB - Mini drak - Mini drak clone, comes with normal vertical stabilizers and tail boom.

Plans are for my dollar tree foam board mini drak replica. Plans include both normal vertical stabilizers and a tail boom setup. If using the tail-boom, reinforce the boom arms with BBQ skewers.

Specs:
-2x 12g servos (3 if using the tail-boom config)
2812 - 1100 to 1450kv motor (1100kv works fine with a 4s, I would not recommend 3s)
8x5 prop
Balances with a 4s - 2200mah or 3s - 3300mah battery all the way up front with my FPV camera and transmitter in the nose.
CG is 15mm from leading...
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#2
finally getting around to maidening these. I have built one with and one without the boom and have like a swappable power pack going on. the cg is 15mm BACK from the leading edge? and does the cg change if i add the booms?
 
#5
Are the Vertical stabilizers on the ends of the wings necessary? Excellent job, BTW... this looks fantastic
Thanks!

They are probably not necessary. As long as you have the large vertical stabilizers or the tail boom setup it should track well still.

I should probably revisit this design at some point. It flys great, but I think if I thinned up the airfoil from 3 spacers/spars to 2, it would be a little more efficient.
 
#6
finally getting around to maidening these. I have built one with and one without the boom and have like a swappable power pack going on. the cg is 15mm BACK from the leading edge? and does the cg change if i add the booms?
Sorry for the huge delay, but that is correct. 15mm back from the leading edge. Measure that distance close to where the fuselage meets the wings.
 
#10
Rad! Thanks! I thought about trying a hollow spar with a B fold... do you think that would help? Keep it the same size, but make it hollow?
Weight savings is never a bad thing, and a hollow box spar would probably be stronger than the stacked foam. Mostly the airfoil is just super thick at the spar. When I first made this, the long chord length at the wing root made it seem too thin with only a 1/2" thick (2 foam thickness) spar, so I added the 3rd foam piece. It works just seems too draggy. (I have a real mini drak as well, and the airfoil is quite a bit thinner than my version). Mine is more stretched ClarkY than MH30.

I also think a redesign of the motor mount to ditch the FT firewall and go to a more tapered/aerodynamic 3d print would help. I'm sure it has a station wagon like drag coefficient right now.

That being said, with the tail boom setup, this thing flys smooooooth. The speed is very reasonable as well. Getting some efficiency back so it could fly on 3s comfortably would probably be a good path, instead of just brute forcing through it with more thrust. That being said I did pick up a 1450kv motor specifically to get some more oomph out of the 8x6 prop.

It seemed happiest at 75% throttle, but comfortably flies a lot slower. I figured a little more prop RPM couldn't hurt.

I'm excited to see what you come up with and I think it will be awesome to see how far you can take and improve this design.