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 bucko, Three motors, and a Nose Cone. Well, blow me down! Blimey! Arrr! 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. Well, blow me down! Blimey! T' body tube be cut t' a length o' 19 inches and set aside. T' BT-20 motor mount was cut into 3 - 3 inch pieces and then t' thrust rings glued in. They are glued together into a triangular shape. Avast! 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. Arrr! T' motor mounts, now dry, me bucko, is glued in t' body flush with t' end o' t' tube. Avast, me proud beauty! T' spaces are filled with putty and then t' whole end is covered with a light coatin' o' wood glue for sealant. Aye aye! T' tube is marked for three fins and they are glued on. Arrr! Well, blow me down! Do glue fillets when dry. Build a shock cord mount and attach t' t' interior o' t' body tube. Arrr! Ya scallywag! Attach t' shock cord t' t' nose and t' parachute about 6 inches down t' shock cord. Avast! Cut the launch lug into t' 1 inch pieces and attach one near t' empty CG point, about 8 inches from t' aft o' t' body tube, arrr, ya bilge rat, shiver me timbers, and t' other 2 i! nches from t' end of t' tube. Avast! 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, matey, then I masked off t' tip o' t' nose cone and 1 inch o' t' tips of t' fins. Avast! I then gave t' rocket a few coats o' a beautiful dark red. Avast, me proud beauty! The rocket is then given a gloss clear coat.

Flight: T' first flight was at a local park usin' three B6-4's. Begad! The rocket was prepped normally with waddin' and motors installed. Aye aye! A clip-whip was used t' ensure ignition. Well, blow me down! Ya scallywag! A 5-count was given. Aye aye! Ignition was very slow. Begad! The rocket lifted o' t' pad, ya bilge rat, climbed about 50 feet then fell horizontal and headed about 300 feet downrange. It barely slowed down before ejection. Blimey! T' chute popped and rocket was recovered. Arrr! Upon inspection t' see what went wrong, me bucko, we found that only two motors lit, ya bilge rat, me hearties, apparently causin' t' rocket t' head downrange like it did. Ahoy! Ahoy! No damage was apparent. Blimey! 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. Well, blow me down! 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. Ahoy! Clip-whips were used. T' rocket had plenty o' power this time, me bucko, climbin' t' about 600 feet. Avast, me proud beauty! Aye aye! Liftoff was very quick, with power translatin' out t' about a D18, arrr, matey, I think. Blimey! Ahoy! Ejection was just before apogee. T' rocket was recovered with no damage.

Summary: Overall, this is a great cluster rocket.

comment Post a Comment