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FT Bronco mod --> P-38 Lightning!

#1
Hi everybody,

I just finished the prototype of my P-38 mod to the FT Bronco design. I really like the Bronco, but I wasn't a huge fan of the way the center fuselage looked. I also reeeeeally like the P-38 Lightning, so if I was going to change things around, why not make it more P-38-like? There are a few notable changes I made to the design, but they're mostly aesthetic.

1. Wing design: I used a three-view diagram of a P-38 to establish a ratio of boom-length to wingspan. This gave me a wingspan of 50", which is about 6" longer than the Bronco. I also added a taper and the rounded wing tips of the P-38. My wing template is shown below:

IMG_20151031_003816-2.jpg

2. Tail-end control surfaces: I reshaped the elevator and rudders to have rounded tips. The rudders don't go below the boom like they do on the P-38, but I decided that I'd rather keep the extra ground clearance of the Bronco.

IMG_20151101_171625-2.jpg IMG_20151101_223202-2.jpg

3. Retractable landing gear! I used this set from Hobbyking: Turnigy 90 degree Tricycle Retract System (2kg AUW max)

I cut out pieces from plywood, glued them to the bottom of the center fuselage and power pods, then used screws through the foam, into the wood from the inside to mount the retracts. It is nice that two of the retracts will move with the power pods, in case I want to try this system on something else.

IMG_20151111_022642-2.jpg

4. Center fuselage: I used the plans from Filken's P-38 article. I had to change the wing cutout of course, but that was pretty much it. Lots of room inside for all the wiring, and the nose is the perfect width to fit my GoPro Hero with the protective case! Thanks Filken!

IMG_20151111_022559-2.jpg

My wife and I went down to the flying field earlier this evening and did the maiden flight of this bird. It was very nice!! She taxied, took off and flew a few patterns really well with 50% throws in bank-and-yank mode. Unfortunately I botched the landing... but even so everything is still A-OK.

Here is the video!


Some specs:

Motors: Turnigy D3530-14 1100kv with HK 30A esc's
Props: 8x4.5, counter-rotating (10" diameter props will fit, will try these soon)
Wingspan: 50" (1270 mm)
AUW: 2.5 lbs (1134 g) with 2200 mAh 3S 30C LiPo
 
#5
Haha yea, not sure why my wife decided to keep the phone in profile while filming. I thought about using my GoPro Hero but it was dusk and the low light on that thing suuuuuuucks. Maybe at some point I'll get around to doing some editing and crop the vid into a better aspect ratio.
 
#9
Thanks Jamboree and el Gato!

I've got a can of Minwax and gray spray paint ready to go! I'm thinking a simple gray scheme with a couple WW2 era roundels. Will definitely post pics when that happens.
 
#11
Very nice looking plane.

Also made some mods to the Bronco fuse:

IMAG1642.jpg

IMAG1648.jpg

Will make mods to the rudder also to give it more scale look :) .
 
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#15
Nice plane and great work.
However the 2 * 35mm motors that you use are just over powered and way too heavy.
I have modified a Bix3 to bi-motor using some 3d printed motor mounts hot-glued to the wings.
I have used 2*28mm 1000kv motors with 20A escs and spinning a pair of 8x6 props.
Plenty of power with 3s 2200 mAh you really don't need more.
Also very economic, at full throttle both motors are pulling only 17A.
The 35mm motors that you use are able to fly alone each one of them your plane.
 
#16
Paul, I agree with you 100%, also I was badly under-propped with 8045's on there. After I repaired the crash damage I put some 1047's on and thrust and handling was much improved. I got those 35mm motors because I was looking for a "beef" equivalent setup. Maybe at some point I'll invest in some smaller motors and try those out.