Scratch Mark VI Original Design / Scratch Built

Scratch - Mark VI {Scratch}

Contributed by Darren Longhorn

Manufacturer: Scratch
Mark VI
(Contributed - by Darren Longhorn)

PoserT' success o' the MkV made me start t' think a bout t' bigger tubes I had stacked in t' corner. If I could cluster four engines, ya bilge rat, why nay six? Why nay use D engines? I had a tube that would hold seven 24mm mounts, matey, but it wasn't really long enough. Ya scallywag! So I decided t' built a rocket reminiscent o' t' MkIV, with a transition, arrr, and forward fins. Arrr! With t' extra weight o' t' engines, arrr, t' plywood fins and centerin' rings, me bucko, me hearties, this design turned out nay t' be stable ( Usin' RockSim). Begad! Ahoy! I increased t' length o' t' upper tube ( forward o' t' transition) and removed the forward fins. That was a lot better.

Engines installedI had heard o' some larger black powder engines available in t' UK form a company called Rocket Services and wanted t' option o' installin' them. Avast! Ya scallywag! So I went for a removable cartridge system. Avast, me proud beauty! T' Fins were mounted through t' body wall and formed runners onto which t' engine cartridge would slide. Aye aye! T' cartridge was made up from two discs o' plywood drilled with holes for t' engine mounts. T' cartridge slid in t' t' body on t' runners and was then locked into position by rotatin' the whole thing. Begad! In t' end I just went with six engines. Blimey! Avast! Thrust rings were made from sawn up spent D engines and epoxied in t' place. A stuffer tube was placed inside t' main body, matey, matey, mounted on two centerin' rings. Arrr! At ignition t' upper body be t' separate, ya bilge rat, ya bilge rat, each half with its own parachute. Well, blow me down! Avast, shiver me timbers, me proud beauty! Karen made a red and white hemispherical 'chute for t' lower half, and I was goin' t' use t' pink circular 'chute for t' upper half. Avast! Avast! We intended t' fly it at t' International Rocket Weekend, and I had a lot o' help from Brain who made and painted the transition just days before we went. Begad! Avast, me proud beauty!

PreppedAt t' event, me bucko, matey, a lot o' doubt was raised about t' engine cartridge system. Blimey! Avast! 'Six D ejection charges will blow it out' they said. Avast! I also couldn't determine how I was goin' t' ensure that both parachutes deployed. Begad! In t' end I bought some big shock cord and tied both halves together on t' red & white 'chute. Avast, me proud beauty! Avast, ya bilge rat, me proud beauty! Another hitch, I had planned to add another set o' clips t' me ignition system, but had forgotten ( that last week was hectic as I me work had taken me away from home for several days), and I didn't have a large enough launch pad... Avast!

Lift offLuckily I learned o' a new technique for clustering. Begad! Blimey! This involves usin' a single igniter t' ignite 'quick match' fuses that are fed into t' individual engines. Avast! Blimey! One o' t' organizers, John Bonsor, me bucko, showed me how t' do this. I managed t' borrow a launcher and after a wait for t' wind t' die down, shiver me timbers, we were ready. T' ignition and initial flight were perfect, matey, me hearties, except, what be that? A small object appeared t' fly from the back at ejection, ya bilge rat, and where was t' 'chute. Blimey! Blimey! Blimey! Blimey! T' rocket came in ballistically. What had happened was exactly what t' 'doom sayers' were predicting. Aye aye! Blimey! Arrr! Blimey! Even though I had staggered t' ejection by usin' a mixture o' D12 delays, matey, matey, the ejection gases pushed t' engine cartridge out o' t' rear, instead of deployin' t' chute. Avast! Blimey! T' rocket was a write off. Avast, ya bilge rat, me proud beauty! Blimey! T' engine cartridge shattered, arrr, t' forward tube like a concertina, and t' aft tube a slowly unwindin' spiral.

T' pic o' lift off was t' last shout from me last roll o' film, shiver me timbers, so mercifully thar are no pictures o' t' rocket as we found it. Well, blow me down! Blimey! Well, blow me down! Blimey! T' realization of t' hours we had all spent on this rocket, ya bilge rat, me bucko, shiver me timbers, which was now trash, arrr, didn't sink in until later, and it was a long drive home from Largs t' Leeds.

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