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Oct 21, 2019, 06:46 AM
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Flyitall's Avatar
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Zippy Little Thing


I thought that I would share a new model that I have just built. It all started off with me seeing the remains of a Hangar 9 10cc Ultra Stick lying in a hobby shop. The bright red colors struck me as being quite vivid.

I wanted an all balsa wood airframe, as I love building these structures. I wanted the vivid colors. I had to have a properly sheeted wing to avoid steps in the airfoil, and I wanted a cowled in motor. I made a sketch of the proposed airplane.
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Oct 21, 2019, 06:52 AM
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I then drew up a plan. As I'm old school, I used my old drawing board and quickly came up with what I wanted. I chose a low Reynolds number airfoil, fully symmetrical, and 14% thick.
I looked at power and thrust to weight ratios, and selected a 3530/1100 Turnigy (similar performance to my AXI 2808) which I had already. I wanted to fly 2200/3s and thus sized the aircraft around these parameters.
Oct 21, 2019, 07:06 AM
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Out with the balsa wood, and start cutting out parts! I built the wing first.

I learnt to fly RC many years ago, and my first model was a Carl Goldberg Snr. Falcon. It had nice rounded wingtips and had an airfoil section horizontal stabilizer. These ideas were incorporated into the new model. The Falcon was a good flying airplane and I liked the rounded off look of the tips.

Wanting good performance, lightweight wood was chosen for low stress areas of the airframe. I needed a lightweight landing gear too, so I made one up using carbon fibre and epoxy resin, using a wooden form to lay the fibres onto. It weighs 17 grams, half the weight of an aluminum version.
Oct 21, 2019, 07:11 AM
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The fuselage was next. I had to have a nice aerodynamically designed nose, but needed cooling of the motor and ESC. A nose intake under the spinner was created, with the air exiting from the rear edge of the top hatch, in front of the wing. A small gap allows the air to escape into a low pressure area above the wing.
Oct 21, 2019, 07:20 AM
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The vertical and horizontal stabs were next. A built up HS seems a bit overkill, but it is very light and is stiff in torsion, so no warping. Well worth the effort.
The vertical stab was built using sticks, but when I covered it with iron on film, it warped slightly, so I ripped the covering off and skinned the fin and rudder with 3/32 balsa. This made a huge difference and hardly added any weight.
Oct 21, 2019, 07:29 AM
I just want to go fly!
walter3rd's Avatar
That nose is a work of art! Well done
Oct 21, 2019, 07:33 AM
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The completed model came out at 499 grams without a lipo. A 2200/3s weighs 171 grams, giving an all up weight of 670 grams ready to fly. The power setup was tested using a 10x7E APC propeller and produced 270W at 24.5 Amps. This amounts to a power to weight ratio of 182W per pound! Fun stuff!
The model flew beautifully and has sparkling performance on the 10x7. I am also going to try a 9x9 just for fun, to see how fast it will go. The motor is cool after landing so I am pleased with the cooling.

Turnigy 3530/1100
30 Amp Hobby Wing ESC
2200/3S Gens Ace lipo
Futaba S3114 servos (4x)
Futaba 6106 HFC Receiver

Wingspan 38 inches
Wing area 343 sq. inches
Oct 21, 2019, 07:42 AM
'Douglas' to his friends.
An excellent topic, suitably concise, which whets the appetite. Is there any chance of seeing the completed plan published (on Outerzone, for instance...)..? Too much 'muscle' for my flying style, but Our Eldest could be interested in such a smart-looking performance 'plane. Thanks for sharing, in any case.
Oct 21, 2019, 07:55 AM
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Thanks for the kind words Dad
I'll try and find a way of scanning the plan and getting a copy onto one of the free plans websites.
Oct 21, 2019, 08:34 AM
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Very nice work!

CD
Oct 21, 2019, 09:56 AM
UAS Pilot - FAA# *******HRK
CryHavoc's Avatar
Reminds me of the old Airtrax kits. Taper the wings you'd swear it was one.

Mike
Oct 21, 2019, 01:46 PM
B for Bruce
BMatthews's Avatar
Nice build and nice design. You also clearly "know your balsa" to make a model like this which came out so nicely light for what it is. Just first class all around.

At the speed this must fly when at full throttle it must get small REALLY fast....
Oct 22, 2019, 01:23 PM
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That is gorgeous craftsmanship. She needs some wheel pants!
Oct 22, 2019, 03:34 PM
Wanted for breaking Ohm's Law
Dennis Sumner's Avatar
Real nice design and build! Love the details on the cowl....nice to see builders doing it all.
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