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Re: SZD Cobra 17

Posted: 25 Apr 2020, 20:24
by Jolly Roger
How exciting! Bet you can't wait for tomorrow morning. :)

Re: SZD Cobra 17

Posted: 08 May 2020, 16:50
by Chris Bowles
While I waited for the epoxy to fully cure on the wings, poor excuse, cut and shaped 1/4" ply to form the cockpit frame, this was glued in, then glassed, small magnets where glued in to retain the canopy, a piece of foam was shaped to form a mould for the tail wheel, glass cloth was wrapped the mould, when cured, the foam can be removed, leaving a nice housing for the tailwheel, and no muck going up into the fuz,
using my patio as a grid reference, the fuz was lined up, the wing joiner tube and wings fitted and lined up,
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using a piece of string taped to the fin, square tape measure and eye, when happy the tube was tacked in place, the wings removed, and the tube fully fixed, next the wing roots where placed over the wing tube,wings refixed, incidence checked, and the roots glued in place, then balsa and filler was placed in the gap

Re: SZD Cobra 17

Posted: 08 May 2020, 23:28
by Jolly Roger
It's coming along really nicely Chris. You've got a lovely finish in the fuselage.

Re: SZD Cobra 17

Posted: 09 May 2020, 10:07
by roo Hawkins
what a fantastic looking job you are doing. looking nice. roo :D

Re: SZD Cobra 17

Posted: 22 May 2020, 16:24
by Chris Bowles
a bit more progress, have made the canopy frame, this was cut from 6mm ply, then 4x4mm ply was glued on the edge to give a larger glueing area, canopy cut, glued and painted, the canopy I used is for the 1/3 scale ASW15, also have made a retract unit, the full size came with a fixed wheel,
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but a retractable wheel was a option, have found that a fixed wheel model, can sometimes be a bit of a pain to store or transport, so went for the flat bottom version

Re: SZD Cobra 17

Posted: 22 May 2020, 19:52
by Barry_Cole
Nice looking retract, but please use a servo that moves 180 degrees. Then there is no load on the servo at either end, and it will stay locked down much more reliably.

8-) 8-) 8-) 8-)

BC

Re: SZD Cobra 17

Posted: 22 May 2020, 20:06
by Chris Bowles
Hi Barry, the standard servo works just fine, with the retract locking in both up and down, being a homemade unit the movement will be different from a commercial one

Re: SZD Cobra 17

Posted: 14 Jun 2020, 14:58
by Chris Bowles
Been a while since the last post, but have been plodding on, got the airbrakes fitted and working, freed up the ailerons, living hinge, primed and painted the wing, before I cut the hole for the retract, I took a mould of the bottom of the fuz, because the fuz is quite thick 4/5mm, having doors that thick dosen't work very well,
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also you can hack out the hole, knowing that you can cut and fit new doors, fitted all the wiring, and installed the rest of the radio gear, balanced the model, then weighed it, came out at 12.5kg should be able to remove some weight after test flying

Re: SZD Cobra 17

Posted: 14 Jun 2020, 19:59
by B Sharp
That's looking really good Chris. I look forward to hearing about the maiden.
Brian. :)

Re: SZD Cobra 17

Posted: 14 Jun 2020, 20:49
by Chris Bowles
Thanks Brian, will let you know, one way or another, just need a weather window, easterly on our site is not good, it's a race with the tug, who gets to the strip first