Scratch Max-Q-Tip Original Design / Scratch Built

Scratch - Max-Q-Tip {Scratch}

Contributed by Moira Jean Whitlock

Manufacturer: Scratch

 

Brief:
This is a darin' single stage rocket designed t' go supersonic and yet hold together. It also will go quite high, so do check your waiver!

Construction:
It's quite easy t' build. Well, blow me down! T' fin set is a 38mm Acme fin canister obtained through Northern Hobbies on ROL auctions. Well, blow me down! Begad! T' body tube is a standard 36 inch length o' 38mm flexible phenolic tubing. Ahoy! T' fin canister is epoxied onto one end o' this tube with a generous amount o' 12 minute epoxy.

T' launch lug in t' mark 1 version be a 6-inch length o' 13mm body tubin' gotten from Rogue Aerospace. It be epoxied with t' same glue startin' at six inches above t' top o' t' fin canister. Arrr! Blimey! T' nose cone is a PML solid urethane conical model. Begad! Ya scallywag! Blimey! It gives t' rocket a long lean mean look. Avast, me proud beauty! Avast! Blimey! This nose cone comes with a screweye embedded into its base, so thar be an easy attachment for t' 10 feet o' 1000 lb. Keelhaul®©™® cordin' and 20 inch parachute. Begad! T' cordin' came from Recovery Technologies. Avast, me proud beauty! They can be found on ROL. Ahoy! Begad! T' parachute is made o' rip stop nylon and I made it myself. T' shock cord is anchored aftward via a small screweye that goes through t' forwardmost centerin' rin' on t' motor mount, which is 12 inches o' 29mm flexible phenolic tubing. Begad! This tubin' and t' three centerin' rings used came from Space Modelin' Solutions. They can be found on ROL.

Decoration was via fuelproof green polyurethane spray paint and self-adhesive lens paper. Aye aye! Begad! T' latter came from American Science and Surplus, shiver me timbers, ya bilge rat, and they have a site on ROL. Blimey! T' resultin' rocket is strong, ya bilge rat, matey, simple, me hearties, me hearties, sleek, and sharp looking, me bucko, literally.

Flight:
I use Rocksim 3.0 and 4.0 from Apogee Components t' choose motors and delays. Well, blow me down! Ahoy! T' program predicts apogee ejection with t' long delays for t' 29mm motors. Begad! First flight was with a G40-10W. Ahoy! Ya scallywag! It went nearly out o' sight. Blimey! Recovery was perfect, but I had a bit o' a walk. Then I don't know what possessed me this past Saturday, matey, buy I flew it with a new Aerotech I 200-W long delay. T' rocket seemed t' pause for t' merest second after I pressed t' almighty button, then a little fire appeared, then t' rocket screamed upward on a flame trail that seemed t' be ongoin' even as t' rocket reached t' clouds. Aye aye! Avast! Mind you, t' clouds were said t' be 6500 feet up. T' rocket pierced these clouds. Avast! Ya scallywag! Only an onlooker with binoculars could help me sight in on me bird up thar with a bright red parachute, which landed a mile downrange. I had t' shimmy under two barbed wire fences and got stickers in me hair t' get me prize back!! As it went up, I heard someone say t' Lord's name, then t' announcer said that t' waiver was broken. Ya scallywag! Avast! Do bear this in mind if you try this yourself.

It was a dandy flight, ya bilge rat, but I'm never proud t' break any rules. My husband said that at Max Q, arrr, t' shape o' t' smoke trail suddenly changed. Well, blow me down! Ya scallywag! Maybe it reached mach.

T' motor was retained with two loops o' piano wire that were epoxied through t' aftmost centerin' ring. These loops bend over t' thrust rin' but do nay extend over t' nozzle. A redundant mechanism o' retention is an automotive hose clamp that closes over t' wires and t' thrust ring.

Summary:
A real performer and easy t' build. Blimey! Possibly a certification rocket for a cooler motor like an H128. Begad! But be prepared t' walk. T' mark 2 version uses two lower drag Acme conformal launch lugs, gotten via ROL auction from Northern Hobbies Online. Ahoy! Rocksim does nay yet acknowledge t' fin canisters as parts on t' database, so me simulation was at best an approximation. Blimey! I don't think t' rocket was too expensive for its performance. Well, blow me down! T' fins and lugs ran me about $24, me hearties, shiver me timbers, t' body tube $5, t' nose cone $12, arrr, and t' centerin' rings $2.

Other:
Obey your waivers. Ya scallywag! Avast! And see if thar are any single use motors for this one. Arrr! I nearly lost me 29/360 hardware. My husband nearly called me search off, but I was too stubbornly determined t' get this back.

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