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SG 38 Zogling - Primary Glider


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Really excellent job, Stuartthumbs up

I'm wondering, is there any possibility that you could fit the powerpod behind the pilot? Perhaps reduce the prop diameter by an inch and increase the pitch to maintain the thrust, if it all fits in. That would restore the clean flying lines of the prototype.

Pete

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Hi FB3

Stuart's SG-38 is his first scratch build and he wanted to keep it scale .As our flying site has limitations that would make bungee or aero tow with a big model difficult so he reluctantly decided to add power, but fortunately the "A" frame that extends above the wing lends it's self very well to attaching a pod ,which was simply made with two pieces of ply located either side of the"A"frame and then using balsa block to form the nacelle which was fitted to give 5 degrees upthrust ,as the thrust line is above c/g .A circular ply face was then glued to the pod face to take the motor mounting bracket.

Although the model weighs 10 lbs the 16" x 6" wooden prop returned 600W from a 3.7A lipo so that kept the power train simple and economical .

It was a real pleasure to see a truly vintage design and is a credit to Stuart's dedication and ingenuity.

Tom.

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Gosh this thread has been busy! Well as Tom say's the power pod was a necessity at our flying site. I could mount a pusher motor behind the wing but I think it might need more nose weight and I want to keep the wing loading low. However it's a good idea .

Taco my next project is going to be the 1/4 scale ASK 18 from the Cliff Charlesworth plans, its a beauty with a wingspan of 4 metres!.

The ribs were done by printing out paper templates using one of the free airfoil plotting programs. I then cut the templates out with about 1/8th inch all round the rib extra and glued/with pritt stick to sheet balsa, then simply cut around the lines to free the rib!.

I am making some little posts within the wings to take the wire bracing which goes from tow attachemnt points on the wing (top and bottom) to various places on the fuz, this will stiften things up and add more rigidity to the airframe. I will use some of that pull pull control cable that is plastic covered as it has a high tensile breaking strength.

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Thanks Tom and Stuart, re info ribs, thrust line etc. Its great that info given freely on a model can be applied to many other models, and bespoke power pods, together with great pictures,help all of us struggling (but winning) to keep up. Cheers, The video is brilliant too. Cheers both.

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Thanks FB3, that would be great .

Today I took the Zogling out for another powered test flight as I have adjusted the thrust line more upwards to give slightly more up-thrust. She flies better now and no longer has that tendency to nose over in the climb!

I have added brass tubes through the wings to take the cable bracing, the ends of the brass tubes have been drilled to receive the closed loop cabling. Next is to make the metal fixtures to which the bracing wires will clip, courtesy of clevises.

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  • 3 weeks later...

The re-shaped pod for the electric motor, still needs a bit more sanding, shaping and painting with wood stain, then the glider will just about be finished smiley

It's been really enjoyable making the SG-38 and now with the better weather she will be even better to fly.

More videos, both of the SG-38 (in flight video) and filmed from the ground will be done in due course.

Edited By Stuart Eggerton on 30/03/2012 22:55:36

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Hi Taco, yes I hope to fly the SG-38 alot this year. I have just about finished the upgrades on the model except for possibly trying a bigger prop and maybe I will make a wing fairing to hide the join between the two wings and hide some of the wiring.

I have made a short video detailing the operation of the pilot (he is connected to the servos in a way) please see this below.

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