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Jul 30, 2014, 05:19 AM
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robertus's Avatar
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Build Log

Yak-17 with plans


Hello, this is my next EDF project, after F-302.
Yak-17 is after maiden flight.
I made him from depron 6mm.


Movie from fligt after trimming.
Yak-17 (3 min 20 sec)



Plans in post #11
Last edited by robertus; Jul 30, 2014 at 10:10 AM.
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Jul 30, 2014, 06:35 AM
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I divided the model into several parts



Cross-sections

Wing has Clark-y airfoil.
Jul 30, 2014, 06:42 AM
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Fuselage is like a box.
On the bottom I've added some depron to round the corners, and wood reinforcements.


Jul 30, 2014, 06:48 AM
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Front part, intake, and tube for EDF.
Build is similar to paper models.


Inlet should be more round but tensions in foam make it more oval.


fitting with no glueing
Jul 30, 2014, 07:11 AM
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Impressive work!!! Tape reinforcement to bend the foam is a excellent idea.. Some day I will uset it.
Congrats
Jul 30, 2014, 07:33 AM
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Yes. It's helping with bending a lot. Without tape, foam can crack.
Jul 30, 2014, 08:17 AM
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Wings.

Wings has Clark-y airfoil but I'm lazy and I've got only two ribs.

Reinforcements with carbon tube.


Wings are conected to fuselage by two carbon tube. Lover tube is main girder. Upper tube is helping to mount in correct position.


Now wings are glued to the fuselage


After that I glued the upper wing coating.
Jul 30, 2014, 08:20 AM
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Fuselage's hump is made with 3mm of foam. Easier to bend.

Jul 30, 2014, 08:28 AM
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Mounting the EDF tube, outlet.
Checking...

There is a balsa bar between edf tunnel and lower shell. End some depron strips which helping correct shape of covering.



At the end of the tube I've pasted wide strip of foam that narrows outlet to 100% FSA diameter.
Jul 30, 2014, 08:56 AM
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And finally, the whole model.


Canopy is temporary version. I want to do some vaku and put pilot inside.

Electronics bay.



This is comparison with me

And with my 120cm WS P-40 Tomahawk.
Last edited by robertus; Jul 30, 2014 at 10:12 AM.
Jul 30, 2014, 11:06 AM
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VERY nice !!!
Jul 30, 2014, 02:11 PM
Watt Waster
Tsavah's Avatar

Yak-17 Foam RC Model Airplane


As usual, very nice work. I like the size of your model and didn't realize it was so big. For some reason I thought it was smaller. I noticed you used the scribe and roll method for shaping the foam pieces. Have you tried the cold rolling method on thin foam sheet yet? I think I told you I have a few video on my YouTube channel about how to make curved, or foam tubes without the need to score, or scribe the inside of the foam part.

I use the cold rolling method because it is faster and gives excellent results as long as you start with mild pressure at first and increase the pressure through the rolling tube, or rod, or like device gradually. The only other trick is to do the cold rolling on top of a firm foam rubber pad, or couch cushion. The foam rubber does need to be larger than the foam part to be shaped, and the rolling device needs to be longer than the foam part for hand gripping. That is pretty much all there is to the process of cold rolling thin foam board. You can read and see more in my RC Groups blog. Just click on my Avatar.
Latest blog entry: Center of Gravity - Airplanes
Jul 30, 2014, 03:35 PM
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I use similar method of foam rolling to yours. I'm rolling out foam like pie, kneading by hand or dragging on the edge of the kitchen counter.
Jul 31, 2014, 12:54 PM
Watt Waster
Tsavah's Avatar

Yak 17 - Shaping Foam


I thought you might be shaping the foam parts into curves and tubed that way. Found another YouTube video showing the cold rolling method and the guy taught me a few tricks. When he cold rolls a tube, he over deforms the foam edges and applies a very sticky tape. He then cold rolls the seam before glue is applied to ensure a very round butt joint. Once he is satisfied he has the desired butt joint that will give a very round tube, he pushes the seam inward to open it and applied glue sparingly. Once the glue has set, or a bit longer when it has cured, he can remove the tape.

Most of the time you can see the seam, or butt joint because of the glue color, but otherwise he has a very round foam tube. Of course I end up with the same thing, but sometimes the seams are not quite perfect even though I often make a foam device of the desired shape that helps ensure the short tube, or ring is the desired shape. I will see if I still have a picture of a foam shaping device/tool/jig I have used in the past to give you a better idea of what I mean. I have found it much easier to make more than one copy of the same model using foam shaping devices, but the same tools are useful for one-off models also. Click on the pictures a few times to make them easier to read in a larger version. You can also use the customize tool to enlarge the picture even more if your viewer has the option.
Last edited by Tsavah; Jul 31, 2014 at 01:07 PM. Reason: spelling ...


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