Descon EnRoc

Scratch - EnRoc {Scratch}

Contributed by Kevin Rich

Manufacturer: Scratch
Contributed by - Kevin Rich

The Enema Rocket
or "EnRoc" for short

This little gem actually does what you think just happened - when you get to meet one of these things for real! 

Yes, that is a real live enema tip just like they use in the X-ray departments to give you a "barium enema". I was presented with this one in the form of a pen. Yeah I know... even that is a little warped.

Materials:

  • 1 ea. Barium enema tip (not previously used)
  • 3 ea. leftover plastic fins from an unknown Estes kit that came with two sets
  • Six inches of BT-5 left over from some repair job
  • Two feet of braided "Super Tack" for the shock cord
  • 1 ea. two foot piece of crepe paper for the streamer
  • Masking tape
  • 1 ea. five inch piece of scrap balsa from.......

Construction
The enema tip is exactly the same OD as the BT-5 and has a smaller nipple on the aft end for hooking up the hose in it's real use. I used masking tape to make it fit the tube and we're half way done. Trim the scrap balsa to slip down inside to keep it rigid under power. The Super Tack is tied trough a hole drilled in the nipple and the nose cone is done.

The airframe gets the three fins CA'd on and a launch lug (don't know for sure what it actually is). The Super Tack is tied to a scrap of body tube and glued in with the bottom 1 1/4" in from the bottom and serves as the engine block. Tie on the crepe paper with another piece of Super Tack. Spritz on a little bit of white primer to simulate the barium and..... presto! "EnRoc"

Simulation:
VCP puts CG about 4.5 calibers ahead of CP. A bit overstable, but so what. On a A10-2T Wrasp puts it at about 143 feet with ejection just before apogee.

EnRoc Flight Report:
Well, it hasn't quit raining, snowing, sleeting or blowing up here for months so it hasn't flown yet. But there may be a window of opportunity this weekend so I will hopefully get a flight report in the first part of the coming week.

EnRoc Flight Report March 4, 2001:
It quit snowing and such. In fact it turned out to be a nice day. It was about 35 degrees, mostly clear with about 10-15 mph of wind from the NNW.

First launch - A10-3T, Straight fast boost up to about what Wrasp said (as a guess), nosed over at apogee and.... spit the motor. Oh NO!!!! Ballistic into the parking lot. Doom and gloom on everyone's thoughts. But NO! That enema tip is very resilient and soft. It did however manage to "insert" itself in the mud and when pulled out looked like one I had seen at work. eeeewwwwyyyyy!! A little masking tape, reset the recovery system (spilled out on impact) tape the crap out of another motor and ready to go again.

Second launch - A10-3T, straight and fast again, over at apogee, eject and...... shock cord failure. The airframe just drifted down (feather weight/ tumble recovery) and the "nose cone" came down with the streamer.  No damage at all.

It did seem to me that the ejection charges on these engines was very "robust". The sound on the ground was a quite sharp, loud report.  That's ok.. I will just make the recovery system more robust. All in all it was a real "shot in the @ss"!

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