FT Mini Speedster Depron Scratch Build as Kens CAD

by jmad | February 12, 2015 | (9) Posted in Projects

I love scratch building, so when I saw Mr. Kens of CAD Models Article posted on November 13, 2014, I inmediately wanted to make the plane, making out of depron it would have the advantage of weight, and also I liked the idea of making the fuselage of one piece of foam just bending it.


First of all I needed to contruct a similar baking wing jig as the one shown in the picture of his post, that was easy to do out of wood and aluminum flashing, here are some pictures of mine:


You have to bake the wings in your home oven at 200 degrees F for about 10 minutes, preheating the oven and wing jig before at the same temperature. The wings came out perfect, the advantage is that the curvature of the undercambered wing is the one that you want to give according to the ribs that you make, and once is cooked it's permanent and very strong; anyway I glue a carbon fiber strip under the wing to give extra strenght. The other advantage of making this jig is that you can make another wing of different width and lenght for a different plane. 

If you prefer not to make the jig, there is an alternative, you can roll the depron over an appropiate tube by hand, if you search in youtube you will fine several videos showing how to do it, I have tried it with another plane and the result is good but not as perfect as this jig.

Regarding the fuselage, that it needs to be bended from one piece of depron, I made a modification that you can see in my pdf (plans)  of Mr. Ken's idea, because he suggested having a relief on one side of the fuselage, I tried that but with my poor experience in scratch building I couln't make the fuselange straight. So I move the relief to the back upper part of the fuselage, and for me it was much easier to bend and glue. Also in order for not heating the fuselage (I tried that and did'nt work for me) I cover the areas where I needed to bend with blue painters tape, then I did the bendings without cracking or breaking the depron. In all the project I used gorilla glue.

Here is the links to the plans for making it:

(the rest o the parts are the originals from the Filtetest plans)


Left Wing

Right Wing

The specificatons are almost the same as Mr. Ken's model, mine is only 2 channel (aileron and elevator, no rudder)

Wingspan: 20.5"

Lenght: 17.75"

Motor 1811-2000Kv 10g from Hobbyking

Propeller: Gemfan 5030

ESC 6A Turnigy plush

Servos: HXT500

Receiver: Orange Rx R410X

Battery: 350mAh 2s

AUW 110 grams

Weight without landing gear 100.4 grams

 Another picture showing the battery compartment in the front and the carbon fiber strip under the wing.

Here are some pictures in flight

I consider that it's not a beginners plane, but with travel adjusted to 85% and 20% Expo in ailerons and 60% travel 20% Expo in elevator  it flies really incredible, stable an very agile.

Here are some videos

A Foam board wing in the jig

Already cooked and dry


Thanks for reading and greetings from Mexico, we are big fans of Flitetest.


BitOne on February 20, 2015
I love the oven rig to form the wings ! I just to find some aluminium sheet that thick, but cool idea and nice result.

The paint job is really nice. Any tips on the paint to use ?
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jmad on February 20, 2015
Thanks for the comments, I think you can find the aluminum flashing in Home Depot, here in Mexico I got it from an aluminum window store, it's 0.020" thick.
I painted the model with acrylic paint from any craft store using a foam brush, I don't think it added that much weight, the black line is a self-adhesive vinyl stripe from Autozone, and I cut the white sticker from a self adhesive roll of vinyl.
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flying pig on March 4, 2015
I love the color scheme and design great work
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jmad on March 6, 2015
Thanks, and it flies very well, it only needs a very calm day
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c.sitas on February 21, 2015
Go to a building supply for the thin aluminum sheets. It'll come in a roll usually. Can be bought in a bunch of different widths. Is called flashing. Can also be bought as soffit material. A cheaper way to get it is to know a carpenter friend and beg some from him. Also a regular lumber yard works good . There you can buy by the foot instead of a whole roll. Much cheaper.
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QuasiFPV on February 23, 2015
Very nice, clean build. It looks like a kit! Great job.
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jmad on February 24, 2015
Thanks, I really appreciate it
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Tyflyer on February 28, 2015
Great looking build I think the wing cooking idea is great, could it maybe used with dollar tree foam board?
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jmad on March 6, 2015
I made some test cooking a foam board wing, and yes it can be done, I didn't used dollar tree foam board because I can't get it here in Mexico, but the results are very good. Once you cut the wing profile you have to wet both faces of the foam board with water, I used a water spray bottle, this in order to soften the cardboard, then I put the wet wing on the jig and bend it and put it in the oven just as the depron one, around 12 minutes and at 200 degrees. After that I took the jig out of the oven and leave it for 24 hours for the water to completly evaporate, and thats it the wing is ready. I found that it has a tendency to curve a little bit after it dries completly, but I'm sure It'll not affect.
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jmad on March 6, 2015
I added some pictures in the article with the foam board used
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jmad on February 28, 2015
Thanks, I've never tried the oven jig using foam board, but it's a good idea, I'll try it and let you know what happens
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akmk10000 on February 24, 2015
Very nice. I love the smooth airfoil and the seamless topside on the fuse.

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jmad on February 24, 2015
Thank you so much for your comments.
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FT Mini Speedster Depron Scratch Build as Kens CAD