Gabriel III Original Design / Scratch Built

Scratch - Gabriel III {Scratch}

Contributed by Marlin Meyer

Published: 2010-12-12
Manufacturer: Scratch

BT-60 based, single stage, scale-like missile. Recovery with 18" parachute

All parts are Semroc numbers:

  • BNC-60L nose cone
  • SE-3 screw eye
  • BT-60 body tube (18 inches)
  • BT-50 engine tube (3 inches)
  • RA-5060 centering rings (3)
  • 1/4" balsa fins (8)
  • LL-423 launch lugs (2)

I started by attaching a Rocketarium 24mm motor retainer to a 3" length of BT-50 tubing with JB Weld. As per the instructions from Rocketarium, the end of the tube and the inside of the retainer ring were "roughed up." Construction of the motor mount followed as usual. The motor mount was mounted so the retention system sits flush with the end of the body tube. The entire body tube was lightly sanded and marked for a 4-fin design. After the fins were attached and fillets dry, I installed the launch lugs. Shock cord was attached with an additional centering ring about 4-5 inches from the top of the body tube that doubles as a parachute shelf. This is a design feature found in Launch Pad rockets and helps prevent parachutes from shifting on lift-off and change the CG. If you plan on using an altimeter, don't forget to drill some holes.

To begin the painting process I masked off the motor retainer. Then I sprayed a coat of Rustoleum sandable auto primer and sanded, did some minor repairs and sprayed and sanded once again. This was followed by several light coats of Krylon gloss white paint. I sprayed just beyond the white areas instead of the entire body to keep the weight down and not waste paint. After a couple of days to dry, I masked the white areas and the fin can. Next I sprayed light gray all exposed areas. Again a couple days to dry. Finally, I bagged the entire rocket except for the fin can and sprayed it and the nose cone gloss black. I enjoy making decals, but have become a real fan of "Sandman's" stuff at Excelsior Rocketry. He offers a set of decals for the LP version of this missile. I had him downscale them to BT-60 size. Decal placement was achieved from pictures I could find on the web.

The design included a Rocketarium 24mm motor retention system. This added a 7g weight to the aft end of the rocket. To better balance the design, instead of nose weight, I included the Micro-Beacon (approx 15g) My first flight was with an Estes D12-5. The chute was a little early but close enough to apogee it didn't do any damage. Second flight was on E6-6. I achieved over 2500 feet on this one and thought I was going to lose it. Good thing I was on a very large field with others to spot. Both flights I used Nomex instead of wadding.

The shock cord was 150lb Kevlar. I had no damage after two flights. The 18" parachute drifted pretty far (about 650 feet), but brought it down gently. I'm constantly playing with chutes of different diameters so my chutes all have snap swivels. Perhaps a smaller chute would be better for flying on smaller fields.



The motor retention system is really nice! Excelsior Rocketry's decals really made it look sharp!


Perhaps a little too much power. I think the design will fly great with 18mm motors as well if you use an adapter. This would be wise on smaller fields.

The big bright colored chute helps track the light colored rocket but drifts quite a bit. I will experiment with spill holes or perhaps a smaller chute.

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