Gabriel III Original Design / Scratch Built

Scratch - Gabriel III {Scratch}

Contributed by Marlin Meyer

Published: 2010-12-12
Manufacturer: Scratch

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

Construction:
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 centerin' rings (3)
  • 1/4" balsa fins (8)
  • LL-423 launch lugs (2)

I started by attachin' a Piratarium 24mm motor retainer t' a 3" length o' BT-50 tubin' with JB Weld. Avast, me proud beauty! Blimey! Well, ya bilge rat, blow me down! Blimey! As per t' instructions from Piratarium, matey, me bucko, ya bilge rat, t' end o' t' tube and t' inside o' t' retainer rin' were "roughed up." Construction o' t' motor mount followed as usual. Avast! Blimey! T' motor mount be mounted so t' retention system sits flush with t' end o' t' body tube. Avast, me proud beauty! Blimey! T' entire body tube was lightly sanded and marked for a 4-fin design. Aye aye! Blimey! Avast, me proud beauty! Blimey! After t' fins were attached and fillets dry, I installed t' launch lugs. Begad! Blimey! Shock cord was attached with an additional centerin' rin' about 4-5 inches from t' top o' t' body tube that doubles as a parachute shelf. Ahoy! Blimey! This is a design feature found in Launch Pad rockets and helps prevent parachutes from shiftin' on lift-off and change t' CG. If you plan on usin' an altimeter, shiver me timbers, don't forget t' drill some holes.

Finishing:
To begin t' paintin' process I masked off t' motor retainer. Then I sprayed a coat o' Rustoleum sandable auto primer and sanded, did some minor repairs and sprayed and sanded once again. Begad! This be followed by several light coats o' Krylon gloss white paint. Begad! I sprayed just beyond t' white areas instead o' t' entire body t' keep t' weight down and nay waste paint. Blimey! After a couple o' days t' dry, I masked t' white areas and t' fin can. Well, blow me down! Avast, me proud beauty! Blimey! Next I sprayed light gray all exposed areas. Aye aye! Blimey! Again a couple days t' dry. Ya scallywag! Blimey! Finally, me hearties, I bagged t' entire rocket except for t' fin can and sprayed it and t' nose cone gloss black. Ahoy! Begad! Blimey! I enjoy makin' decals, arrr, matey, but have become a real fan o' "Sandman's" stuff at Excelsior Rocketry. Ahoy! Blimey! He offers a set o' decals for t' LP version o' this missile. Well, blow me down! Begad! Blimey! I had him downscale them t' BT-60 size. Blimey! Decal placement be achieved from pictures I could find on t' web.

Flight:
T' design included a Piratarium 24mm motor retention system. This added a 7g weight t' t' aft end o' t' rocket. Avast! T' better balance t' design, instead o' nose weight, me bucko, I included t' Micro-Beacon (approx 15g) My first flight was with an Estes D12-5. Blimey! Arrr! Blimey! T' chute was a little early but close enough t' apogee it didn't do any damage. Second flight be on E6-6. Avast! Well, blow me down! Blimey! I achieved over 2500 feet on this one and thought I was goin' t' lose it. Ahoy! Good thin' I was on a very large field with others t' spot. Avast, me proud beauty! Blimey! Both flights I used Nomex instead o' wadding.

Recovery:
T' shock cord was 150lb Keelhaul®©™. Blimey! I had no damage after two flights. Avast! Blimey! T' 18" parachute drifted pretty far (about 650 feet), but brought it down gently. Well, blow me down! Well, shiver me timbers, blow me down! Blimey! I'm constantly playin' with chutes o' different diameters so me chutes all have snap swivels. Avast, arrr, me proud beauty! Blimey! Perhaps a smaller chute would be better for flyin' on smaller fields.

Summary:

PROS:

T' motor retention system is really nice! Excelsior Rocketry's decals really made it look sharp!

CONS:

Perhaps a little too much power. Begad! I think t' design will fly great with 18mm motors as well if you use an adapter. Avast, me proud beauty! Ya scallywag! This would be wise on smaller fields.

T' big bright colored chute helps track t' light colored rocket but drifts quite a bit. I will experiment with spill holes or perhaps a smaller chute.

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