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Dec 22, 2013, 04:18 PM
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Buzzbomb Pusher conversion


Flight video
Scratch built V-1 Buzzbomb RC pusher parkjet (4 min 7 sec)


I've been slowly going through some of my less flown rocket gliders to convert them for pusher so i can give them some more flight time. Normally this means a slight modification of the motor clip to use my grayson microjet V-3 that is mounted on an adapter. I have to swap a 20a esc for the BEC, and install the motor wires back to the rear and then re-balance. Most of the time I can just use an 800mah 3s pack for this motor on planes up to 16 oz. I normally use a 8002s pack for rocket boost and have the CG set for that, and with the pusher and the 3s pack I normally only have to add a quarter ounce or so to get the CG back to spec.

I decided to modify my Buzzbomb but thought a tractor setup would be better since I wouldn't have to trim the rudder to clear the prop if I did it as a pusher. I considered doing a tractor in the front of the pulsejet pod but there wasn't enough prop clearance in this small of a model(I had done it that way on my larger buzzbomb back in the day).

Well, it was a very interesting day yesterday. Really strange behavior, like it was tail heavy. Had to run it very nose heavy to get any control at all. Had all sorts of adverse yaw in banks. I tried all sorts of down and right thrust and it was slightly better. Finally upon suggestion I tried a bit of aileron reflex and it got better, but still wasn't flying normally. I finally concluded that the rotating airflow over the long rear pulsejet pod was causing the problem. I went home, pulled the ailerons off, changed the tail to a full flying taileron setup(instead of just a full flying elevator, moved the tail servos forward for CG, installed long carbon pushrods, trimmed the rudder to clear the prop and moved that trimmed piece forward of the original rudder to maintain my lateral stability. I re-balanced and painted and got her ready.

What a difference! Totaly neutral, CG is back where it was for the rocket glider, two clicks of roll trim, no elevator trim needed at all! Just flew out of my hand and totally docile. I did give up some roll rate using tail control only, but it still banks fine for normal flying, loops are nice, will putter around slow. Moral of the story, stick to full flying tail and pusher!

I've now got my first X-15, second X-24 liftiing body, SR-71, buzzbomb, SpaceshipOne, and AQM-37 jayhawk flying as pushers now.


Frank
Last edited by burkefj; Dec 23, 2013 at 11:48 AM.
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Mar 28, 2016, 06:01 PM
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J Bergsmith's Avatar
Built the V-1 Buzzbomb per the plans, and balanced per Franks recommendations for the first flights. The V-1 is easy to build, and flies very well as designed. The shape of the V-1 is unmistakable in the air, now if we could only get the brushless motor to make the pulse jet sound.

Fun design to build and fly, and the kit Frank produced for me was quality as usual.
Mar 29, 2016, 04:48 PM
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Short iPhone video of a flight.

V-1 Buzzbomb (1 min 34 sec)


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