6" Bullpup Missile

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burkefj

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Not really a true scratch build, but some modifications to a long oop kit... It's been quite a while since I've built a bigger rocket, I usually scratch build or make them from lightweight foam. This was a 6" PML bullpup kit that belonged to a good rocket buddy of mine named Monty Bennett who untimely passed away several years ago. It was gifted to me a couple of weeks ago by Tim Quigg and while I was stuck at home I finished her up with some great decals from sticker shock. It should be a nice flyer on J and K motors. It'll be right around 12 and 1/2 lb with a j 435 and 20 ounces for balast for my largest planned motor, a K-535. It's funny because a few months ago I was thinking my next project might be a bullpup missile.

First I removed the forward 2 inches of body tube that had the dado cuts for the forward fins because I just didn't think they were going to survive recovery, I then slotted the nose cone and mounted the forward fins in the cone. I removed the piston and put a parachute platform for recovery and to get the parachute weight up higher and reduce the volume needed to be pressurized. I basically inverted the piston and glued it 20" down from the top The coupler helps reinforce recovery loads on the bulk plate. I also installed a fiberglass plate/mount for my 54mm av-bay against the inside of the body tube. I use this mechansim for all my other rockets. The av bay sits on the parachute platform and mounts to the inside of the body tube against the fiberglass plate and is held in place with a screw and it vents externally via two vent holes. The av-bay is covered in nomex to protect it from the ejection charge gasses. I use single deploy at apogee and a backup charge, I don't tend to fly high enough for dual deploy. It has a 7' rocketman chute with deployment bag and 25' of kevlar recovery line with a screamer for location once it lands in the sage brush.

I only had to cut one bulk plate from 1/4" ply I had and buy one 2.25" U bolt. I had the rest.

243712697_954212191882091_5406114246119880825_n.jpg
 
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burkefj

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Here are some sim results and the 2.25" difference in CP using borrowman(OR) or Rocksim.. rocksim at the top. You can also see the internals from the OR sim showing the parachute platform, the offset 54mm altimeter bay etc.

Bullpup Sims RKT.JPG
Bullpup Sims.JPG
 

jqavins

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Nice build. I like the push broom in the background of the picture. There's something about showing a completed project on a clean floor (or deck) with the broom that cleaned it up after the project was done. Even if that's not what really happened.
 

burkefj

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Altimeter deployment, it detects apogee and fires the charges, yes, works very well.

Is the parachute ejected by remote control? The timing is perfect!
Great flights.
 

bschultz32

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IMG_1819.JPG

BurkeFJ, your Forum entry conjured up good old memories of my PML BullDog, Let The Big Dawg Eat. In the picture, that's me carrying her to the launch pad at LDRS in South Carolina in 2000. Flew successfully four times: J460T, J415W, J800T, K550W. The Dawg is resting on a shelf downstairs in my Rocket Room, a grizzled veteran of 15 flights, and with some repair work could fly again. Good times!
Bob Schultz
 

burkefj

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Nice photo Bob! Here is a flight on another J435 last weekend, weathervanes into the wind slightly
 

burkefj

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Perfect flight today, dead straight to 1676'

 
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