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Old Dec 18, 2004, 12:28 PM
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Sukhoi 39 Frogfoot


This is my latest depron 'jet' project. After the Swallow and the Vampire, I decided to make something a bit more 'scale'. I designed it at 40" span, but when I got my enlarged drawings back it looked enormous! After a bit of umming and ahhing, I decided to go with it. Here are some of the components:

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Old Dec 18, 2004, 12:30 PM
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I used white depron for the load bearing formers as it seems to have less 'flex' than the black:

Old Dec 18, 2004, 12:34 PM
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I used some of the techniques I've seen on this forum... The turtle deck has 6mm sq strips added each side. They fit into notches in the formers. I'll have some 'meat' to sand a decent shape...

Old Dec 18, 2004, 12:37 PM
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The engine pods are laminated from 3 layers. The inner 2 are hollowed out. They act as an anchor for the wing, which has an undercambered section...

Old Dec 18, 2004, 12:38 PM
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Whoops, should have said, I'm aiming for a semi-scale model of this:

Old Dec 18, 2004, 12:48 PM
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Power will be supplied by a MEGA 16/15/4 'combat'. The motor will be mounted 'inboard' and will use a 5mm cf rod as an extension, running through 2 ballraces. A mate made me a lovely motor to shaft adaptor...

Old Dec 18, 2004, 01:21 PM
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Looks real good. Nice to have someone make up the s/m bearing. What do you plasn to use for races.

Ralph

PS, I also have found that the black depron is a lighter density than the white.
Old Dec 18, 2004, 01:35 PM
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I got the turtle deck on, also the canopy template, only need to make another eight of 'em! lol



I'm using 5mm internal 11mm external ball races. Another mate found 'em in a heli spares bin at our local shop
Old Dec 18, 2004, 02:06 PM
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Here is the real thing

Kenneth.
Old Dec 18, 2004, 02:11 PM
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Yep, that's the one
Old Dec 18, 2004, 04:11 PM
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smug in granny panties
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You always pick my favorite planes Neil! lol


Barry
Old Dec 19, 2004, 10:12 AM
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Lol, great minds...

I thought I'd put the bits I've done so far together to see what it looks like.



It might look OK after a bit of sanding? OK, a lot of sanding then

I've decided to change the shape of the wings a little. Less sweep, wider tips. The 'scale' wing I cut looked a bit 'tip stally' to me

I'm not convinced about the motor either, but we'll see...
Old Dec 19, 2004, 10:33 AM
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Hey Neil,
looks like a great jet! Good luck with the build!

later,
Dave
Old Dec 19, 2004, 12:31 PM
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Thanks Dave

I cut the 'sport' wing. It has a little more area and the chord at the tips is greater. I threw it together to see what it looked like



Old Dec 19, 2004, 12:43 PM
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Looks like a potential,
have you got any idea about wingloading?
Perhaps if this wing works good, you could try the scale one!

Dave


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