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Project Speedfreak - The 60CM span of speed
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Published
Mar 17 2013 by FaTe
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Big thanks to www.FrSky-RC.com for providing the Receiver unit for this project :)
/imgs/SpeedFreak/0-SpeedFreak-60CM
This design was based on making the model out of materials I already have, the only material I had to actually buy was the carbon fibre rod for the fuselage. I was aiming for a small "micro" model with lots of power much like my Delta designs, the difference being this design is a solid wing and should have glide potential.

The model uses a 1650kv 180W Turnigy Air motor with a 30A Turnigy plush ESC, 4 * Turnigy servos. The motor can pull over 700g static thrust on a 3S lipo pack so the objective of this build was to stay under 350g but have a very strong model.
/imgs/SpeedFreak/01-wing-bottom-enforcement
To build the wing I'm using 1MM balsa wood with 2 carbon fibre strip on the bottom layer, these will stop the majority of wing flex once all bonded together.
/imgs/SpeedFreak/02-depron-1st-layer
The next layer is depron at 6MM thick covering the entire bottom area.
/imgs/SpeedFreak/03-depron-2nd-layer
For the leading edge I'm using a simple "step down" so I added a 3MM depron strip on the forward 1/3 of the wing (3.3CM) and began sanding the layers smooth to each other.
/imgs/SpeedFreak/04-servo-holes-and-trimmed-wing
Because the wing will be fully bonded together it means I need a way to change out servos if needed later. So I added in a gully to the center point where leads can run and more importantly stay.
/imgs/SpeedFreak/05-wrapped-top-balsa
The top balsa layer will be bonded but to help it keep it's shape I soaked the entire balsa strip until it was pliable and then wrapped it around the wing until dry.
/imgs/SpeedFreak/06-servo-leads-installed
Now the top cover is in shape before actually gluing it in place. You can also see how the servo lines are ran.
/imgs/SpeedFreak/07-full-balsa-wrapped-wing
I had intended for the leads to come out of the bottom but later changed to the top. It still demonstrates the servo positions and cut outs.
/imgs/SpeedFreak/08-aileron-diagram
Next are ailerons, I wanted long ailerons for maximum control response at the end of the wing but only 2CM wide. I did this because the majority of fast planes only require a small amount of input to turn and using excessive amounts results in unpredictable flying characteristics.
/imgs/SpeedFreak/09-ailerons-fully-cut
Once the ailerons are cut out I sealed the wing and ailerons with more CA around the edges (FOAM SAFE CA!).
/imgs/SpeedFreak/10-angle-sanded-ailerons
Don't forget to sand the bottom side of the aileron down to a 45 degree angle where it meets the wing, this allows you to hinge your control surface with very small gaps. If you forget this stage then in order for the control surface to move the surface would need hinged with a noticeable gap for it too move up and down.
/imgs/SpeedFreak/11-silver-oracover-wing
I only had silver Oracover left and being truthful I don't like it because it's a complete ass to work with. It makes every imperfection stand out like crazy but seeing this is not a build to spec but a build to "what I've got" it will do.
/imgs/SpeedFreak/12-center-plate-cut-out
The fuselage CF rod is 6MM diameter, I mounted 2 plywood plates (at 1.5MM thick each) to the rod in the wing and tail position aligned up, so I know when I do the rest it will all line up. Note the plate is bonded to the rod with fibre glass cloth. The plate is then bonded to the wing never to be removed. You can see the hole where I original intended for the servos lines to poke out but obviously the plate goes here and at the very center is the rod so no option.
/imgs/SpeedFreak/13-tail-support-plate
Now you can properly see both mount plates. The engine mount is created from a brass pipe piece which is then cut in half - half way and bent out. The 2 halves that stick out are then hammered flat and drilled out. To attach the engine mount to the rod I used UHU 300 plus epoxy which when cured is so strong you would have issues TRYING to rip it off lol.
/imgs/SpeedFreak/14-fuselage-plate-mounted
The fuselage is simple, just a 1.5MM plywood plate bonded to the front CF rod area. This acts as a surface to mount components on.
/imgs/SpeedFreak/15-shared-servo-lead-6-into-4
To save weight on the tail so I can mount the servos on the tail itself I share the power lines of each servo and only run individual signal leads. This turns 6 servo leads (negative, positive, signal * 2) into Negative (shared), Positive (shared) , Signal 1 and Signal 2.
/imgs/SpeedFreak/16-tail-covered-hinged
I kept a front overhang on the tail mount plate so the servos could go here.
/imgs/SpeedFreak/17-30A-turnigy-plush-ESC
The motor mount bottom exceeds the depth of the ESC when the model flies flat, so the motor mount would always hit the ground and not the ESC, but to save impact damage and give a bit of a skid plate I added another piece of carbon fibre plate bonded to the framework quite strongly.
/imgs/SpeedFreak/18-electronics-installed
I'm using a 500mAh 3S lipo pack, this Zippy was just for testing as it's only 20C, I have 35C Turnigy packs for flying.
/imgs/SpeedFreak/19-simple-lipo-velcro-strap
The lipo already velcros to the plywood plate but to really make sure it goes no where I made a simple velcro strap.
/imgs/SpeedFreak/20-RTF-5-by-5-prop
With a 5*5 propeller and the 35C lipos this thing really does pull and I can't wait to try it out :)

I will post a part 2 of the maiden flight and tweaks if any.
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