Scratch Big Head Pete's Spool Rocket Original Design / Scratch Built

Scratch - Big Head Pete's Spool Rocket {Scratch}

Contributed by Pete Lilja

Manufacturer: Scratch
Rating
(Contributed - by Pete Lilja - 11/15/02)

Rocket PicBrief:
15" Spool Rocket with 29 mm MMT and parachute recovery. Arrr!

Construction:
3/16" Aircraft Plywood Disks - 12" diameter
2.6" Body Tube
2.6" Coupler Tube
Parachute
10' TN Shock Cord
Eye Bolts
Quick Links
Motor Retainer

This is a spool rocket was built with standard rocket parts and recovery. T' body tube separates at ejection for parachute recovery.

Top and bottom plates are made from aircraft plywood. Aye aye! A twelve inch circle was drawn and cut out on a band saw then match sanded t' round. Blimey! Circle cutter was used t' 'score' t' top plate so that t' body tube be slightly recessed to give more bite t' t' epoxy fillet.

T' eye bolt used for shock cord attachment passes through t' top plate and an acorn nut be used on t' top outside for finish detail. Aye aye! Avast, me proud beauty! T' bottom plate has a hole that t' body tube passes through. I used T-nuts, ya bilge rat, screws and clips for motor retention as on other rockets. Avast! Launch lugs are simply a 3/8" clearance hole drilled into both plates and aligned when placin' on launch pad/rod.

Flight:
Rocket prep be t' same as any other rocket. Avast! Blimey! Begad! Blimey! Waddin' placed on top o' motor as usual.

I have flown this rocket 9 times on various motors. Aye aye! Blimey! Well, blow me down! Blimey! It crashed on a G35-4 and F20-4. Aye aye! Blimey! Avast! Blimey! On a G80-4 t' parachute barely had time t' open before landing. Avast! Blimey! Ahoy! Blimey! The best flights were on H128 with a short delay and typically an F50-4 works very well. T' F50 be t' perfect SU motor for this rocket and an H97 reload would make for a great flight.

Summary:
This rocket needs a short delay as its coast time is almost non-existent due to its high drag. Ya scallywag! It basically boosts, then stops and begins t' fall. Ya scallywag! Use as short a delay as possible.

It is a fun flyer and is amazin' t' watch. Arrr! Begad! Seein' t' rocket's entire flight profile with t' unaided eye is different from most rocket flights. Well, blow me down! It is nay too often you can see t' boost, apogee, me bucko, ejection and then t' parachute fill. Ya scallywag! T' maximum altitude achieved is nay more than 100 t' 125 feet. Well, blow me down!

Other:
This rocket was an experiment is usin' HPR buildin' techniques/design for a spool. Aye aye! Aye aye! I fiberglassed t' body tube because I am unsure o' t' high drag forces effect on t' body tube. Begad! I do nay know if an un-glassed tube would survive a launch undamaged. Avast, me proud beauty! This is definitely a small field flyer since t' altitude achieved is so low. Arrr! I would have rather built it with a 38mm MMT for a greater range o' motor selection. Well, blow me down! RockSim flight simulations are nay accurate presumably due t' non-standard design. Ya scallywag!

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