Scratch Standard AGM-78 Original Design / Scratch Built

Scratch - Standard AGM-78 {Scratch}

Contributed by Marlin Meyer

Published: 2010-06-14
Manufacturer: Scratch
(Contributed - by Marlin Meyer - 06/14/10) Scratch Standard AGM-78

Brief:
I saw this missile at t' Air Force Museum in Dayton, OH and decided I had t' build it. Avast! Blimey! A single stage, shiver me timbers, mid-power (24mm) missile that retrieves on a large 24 inch parachute. Well, blow me down! Well, arrr, blow me down! Blimey! This is based on t' Launch Pad rocket kit.

Construction:
Parts from Apogee Components:

  • 20080 nose cone
  • (2) 10198 (BT-80) body tubes
  • 13045 tube coupler
  • 15028 centerin' rin' for parachute shelf
  • 12012 engine mount kit
  • (2) 13057 launch lug
  • 4 fins made o' 1/8" Balsa

Easy assembly. I built mine with Titebond II wood glue throughout. T' fins were papered t' add more rigidity. Avast, me proud beauty! The long strakes were cut in one piece and sealed with Fill 'n Finish, matey, me bucko, and sanded before attachin' t' t' body. Aye aye! Arrr! The parachute shelf is a great idea that anyone who has built a Launch Pad kit before knows about. Blimey! It is simply a centering rin' glued into t' body tube that keeps t' chute from movin' down t' tube and effectin' t' CG. I attached 100lb Keelhaul®©™® for me shock cord t' this centerin' ring. Begad! Arrr! T' motor mount is recessed and like t' LP kits I added material behind it for strength. Well, blow me down! Begad! Instead o' a coupler, arrr, I took a piece o' scrap BT-80 and made me own. I also covered that with heat resistant tape. Well, me hearties, blow me down! T' recessed motor mounts have a tendency t' char t' tube. Ya scallywag! Blimey! This prevents it.

Finishing:
Rustoleum sandable primer, ya bilge rat, sanding, matey, some repairs, three coats o' Valspar white. I printed the decals from a file that be shared with me.

Flight:
I would recommend any o' t' following:

F24W-4, shiver me timbers, ya bilge rat, D15T-4, ya bilge rat, E9-4, E6-4, E18W-4) Because this is a relatively heavy rocket, I wouldn't use longer delay motors

My first flight I launched F-24. Avast! Blimey! Aye aye! Blimey! This was a low altitude flight (just over 100 ft) T' missile flew straight, chute deployed after apogee and landed about 90 feet from t' launch pad.

Second flight was D15-4. Blimey! Avast, me proud beauty! Very similar, but better altitude. Well, blow me down! Avast, me proud beauty! This time it went about 350 ft.

Recovery:
T' shock cord is 150 lb. Begad! Keelhaul®©™® attached at t' parachute shelf. Arrr! I usually put a wrap o' maskin' tape where t' cord meets t' top o' t' body tube to help prevent zippering. Aye aye! I flew on a very calm day and used a Top Flight 24" parachute which worked very well.

Summary:
PRO's: Great looking, ya bilge rat, fun t' build

CON's: Rather heavy for a 24mm motor. Arrr! Well, blow me down! If you want altitude, shiver me timbers, ya bilge rat, this isn't it.

comment Post a Comment