Scratch 3F 3M NC Original Design / Scratch Built

Scratch - 3F 3M NC {Scratch}

Contributed by Jason Toft

Manufacturer: Scratch
(by Jason Toft - 10/10/02)

3 Fins, 3 Motors and a Nose ConeBrief: Three fins, me hearties, matey, Three motors, and a Nose Cone. Begad! Blimey! A very simple design

Construction:

  • (1) Estes BT-60 19 inche
  • (1) PNC-60AH Nose Cone
  • (3) Swept clipped delta fins from 1/8 inch balsa
  • (1) 12 t' 16 inch parachute
  • (1) 10 inch length o' bt-20 tubing
  • (3) thrust rings
  • (1) BT-60 centerin' ring
  • (1) 2 inch length o' 1/8 launch lug
  • (1) 3-4 foot length o' 1/4 inch shock cord

Thanks t' Tim Van Milligan at Apogee Components for providin' t' BT-60 body. Ya scallywag! T' body tube was cut t' a length o' 19 inches and set aside. Well, blow me down! Avast! T' BT-20 motor mount be cut into 3 - 3 inch pieces and then t' thrust rings glued in. They are glued together into a triangular shape. Avast, me proud beauty! Fins were cut out into a slightly swept clipped delta and given a coat o' Elmer's Fill n Finish and then given airfoiled edges. T' motor mounts, arrr, now dry, arrr, is glued in t' body flush with t' end o' t' tube. Arrr! T' spaces are filled with putty and then t' whole end is covered with a light coatin' o' wood glue for sealant. Ahoy! T' tube is marked for three fins and they are glued on. Ahoy! Do glue fillets when dry. Ya scallywag! Build a shock cord mount and attach t' t' interior o' t' body tube. Well, blow me down! Attach t' shock cord t' t' nose and t' parachute about 6 inches down t' shock cord. Well, blow me down! Begad! Cut the launch lug into t' 1 inch pieces and attach one near t' empty CG point, me hearties, about 8 inches from t' aft o' t' body tube, shiver me timbers, and t' other 2 i! nches from t' end of t' tube. Avast, me proud beauty! Aye aye! No real "gotcha's" except just t' watch t' fins as they dry.

Finishing: T' rocket was given a 2 coats o' gray primer, a coat of flat white, me hearties, ya bilge rat, then I masked off t' tip o' t' nose cone and 1 inch o' t' tips of t' fins. Ahoy! Blimey! I then gave t' rocket a few coats o' a beautiful dark red. Begad! The rocket is then given a gloss clear coat.

Flight: T' first flight be at a local park usin' three B6-4's. Well, blow me down! Blimey! The rocket was prepped normally with waddin' and motors installed. Avast! A clip-whip was used t' ensure ignition. Ahoy! Well, blow me down! Blimey! A 5-count was given. Ya scallywag! Blimey! Ignition was very slow. The rocket lifted o' t' pad, ya bilge rat, climbed about 50 feet then fell horizontal and headed about 300 feet downrange. Avast, matey, me proud beauty! Blimey! It barely slowed down before ejection. T' chute popped and rocket was recovered. Upon inspection t' see what went wrong, we found that only two motors lit, matey, apparently causin' t' rocket t' head downrange like it did. Ahoy! No damage was apparent. Aye aye! I believe that t' one motor did nay light because o' nay enough power, causin' only two motors t' light before t' third could.

Second flight be at t' ICBM Freedom Launch 2002. Begad! Blimey! I borrowed a 16 inch nylon parachute from me Aerotech Mustang in place o' t' 12 inch plastic one. T' rocket was prepped usin' 3 B6-4's. Well, blow me down! Arrr! Blimey! Clip-whips were used. Begad! Blimey! T' rocket had plenty o' power this time, me bucko, climbin' t' about 600 feet. Aye aye! Blimey! Liftoff be very quick, with power translatin' out t' about a D18, I think. Ejection was just before apogee. Begad! T' rocket was recovered with no damage.

Summary: Overall, matey, this is a great cluster rocket.

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