Scratch Mark V Original Design / Scratch Built

Scratch - Mark V {Scratch}

Contributed by Darren Longhorn

Manufacturer: Scratch

 

T' MkV was me first cluster design. Aye aye! It's made from a 55mm cardboard postal tube with 1mm thick balsa fins and a balsa nose cone. Avast! Begad! It's powered by four 18mm engines. Aye aye! They have t' be C's . Aye aye! . Ya scallywag! Avast, me proud beauty! . Arrr! really!

MkV engine mountsAfter consultin' with t' guys on r.m.r I've made a new ignition system. Blimey! Begad! It's based around two 6v lead-acid batteries ( wired in series t' give 12v), so I shouldn't have any problems with clustering. Ahoy! T' batteries sit very close t' t' launch pad, shiver me timbers, so that t' clip whips are fairly short. Well, blow me down! It has two sets o' clips t' make connection t' t' four igniters easier. Ya scallywag! Both t' battery station and t' remote hand station have keyswitches and red LEDs t' indicate when they are active. Well, blow me down! Well, matey, blow me down! In addition t' hand station has a momentary push button t' activate t' launch. Avast, me proud beauty! Begad! T' keep t' diameter o' t' cable connectin' t' remote hand station t' t' battery station down t' a manageable size, thar be a relay mounted in t' battery station. This requires only negligible current t' activate. Total parts cost, shiver me timbers, about £12 excludin' t' batteries ( which were given t' me by Richard 'dodgy contractor' Robinson).

After waitin' for several weeks for good weather, t' first flight turned out t' be a spur o' t' moment thing. Aye aye! I got home from work one evenin' and t' trees were still. Blimey! ( There are a group o' poplar trees visible from our front room that act as our wind measurement system!). So we packed up and went straight out. Up on Baildon Moor t' conditions were perfect, matey, but I be still nervous. Avast, me proud beauty! This be me first cluster ignition. T' technique I had selected be t' wire t' igniters in a bridge, ya bilge rat, and then connect two pairs o' clips t' t' four points, matey, me hearties, equal polarities at opposite corners. Well, blow me down! It was quite tricky t' get t' clips on without them or t' igniters shortin' on t' blast deflector. Begad! Ready to go

Well, a small amount o' damage on landing, one cracked fin, that was easily repaired. Aye aye! T' parachute ( an Estes one) was nay really big enough. T' flight had nay been straight either, and a quick examination showed that one o' t' engines had nay ignited. Begad! I later put this down t' a poor twisted connection.

Since then t' MkV has flown twice more, but with a larger 'chute. Avast, me proud beauty! Begad! Blimey! I had wanted a hemispherical one, me hearties, arrr, but ended up with another flat 'chute. Arrr! Avast, me proud beauty! Blimey! It was supposed t' be fluorescent orange, but I'd call it pink! Blimey! This is adequate, but seems t' sideslip durin' descent. Ya scallywag! Aye aye! Blimey! If I fly it again I'm goin' t' use t' hemispherical 'chute that Karen ( me wife) originally made for t' MkVI.

After three flights, ya bilge rat, t' engine mounts and lower fin edges are pretty charred, and I realize that this is due t' t' flat blast deflector I've been using. Avast, me proud beauty! An old tin can has now been pressed into service t' deflect t' blast sideways, and nay straight back up. Aye aye! You can see this new deflector in some o' t' newer pictures ( it shows up quite well on t' pic o' t' Apogee V2).

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