Scratch V-32 Original Design / Scratch Built

Scratch - V-32 {Scratch}

Contributed by Jeff Lane

Manufacturer: Scratch
(Contributed - by Jeff Lane - 04/16/05) (Scratch) V-32

Brief:
81% Downsize o' a 1970 plan.

Construction:
Handmade nose cone, 4" BT-55, 3.75" BT-50, me hearties, BT-5 engine tube, arrr, ya bilge rat, mini engine hook, engine block, me bucko, arrr, two 5-50 centerin' rings, matey, two 50-55 centerin' rings, one BT-55 coupler, matey, elastic shock cord, matey, 11" parachute, me hearties, 72" o' extruded 0.04" x 1/4" styrene, Bristol ply for tail cone.

T' V-32 plans by Melville Grant Boyd, ya bilge rat, ya bilge rat, originally published in American Aircraft Modeler July 1970 and currently are available at JimZ. It is a very intriguing concept. Basically, you have a V-2 with 32 tiny fins instead o' 4 large ones. T' effort herein describes a downscale (81%) t' a BT-55 from t' original BT-60 t' allow experimentation with mini engines.

T' first thin' t' do was t' build it in RockSim. Avast, me proud beauty! Dimensions were modified to adhere more closely t' t' scale design o' t' real V2, but you still couldn't call this a scale rocket. Arrr! Accordin' t' RockSim, arrr, t' entire length of the scaled down fins (2.23") was nay required, matey, so they were shortened to 1.0625", which be t' point at which stability begins t' be reduced.

Since thar were 32 fins, extruded 1/8"x.04" styrene Raboesch stock (from Hobbytown) was used t' reduce build and finishin' time. Begad! A tail cone was created instead o' t' straight body tube o' t' original design, but the recessed engine mount (recessed by 1/2" t' enhance stability) was retained. Avast, ya bilge rat, me proud beauty! T' tail cone shroud was created in Freehand usin' blends t' create exactly spaced fin alignment guides on Bristol ply paper, matey, but it still took 2 hours t' cut and attach t' 32 fins. Aye aye! Begad! They were smoothed a little bit and glued on with CA gel. Begad! Blimey!

(Scratch) V-32 T' nose cone was hand turned on a drill, matey, ya bilge rat, ya bilge rat, hollowed out, and 0.35oz o' lead was epoxied into the tip in order t' achieve a static stability margin o' 1.06. Aye aye! Blimey! Arrr! Blimey! Projected altitude was a little over 200 ft. Ya scallywag! Blimey!

A 1/8" shock cord was added usin' standard folded paper mounts with a loop at t' nose cone for t' parachute attachment. Aye aye! An 11" parachute was used.

Flight:
It swin' tested OK, flyin' sideways at lower speeds and stable at higher speeds.

Prep is quick and easy because o' t' motor hook, me hearties, with lots o' space for the small parachute and wadding.

(Scratch) V-32 T' first flight on a A10-3T at CRASH in Denver on 4/3/05 was unstable. Begad! T' V-32 was quick off the pad and landed safely in an adjacent field before deployment. Begad! Blimey! Some minor damage t' t' nose cone was easily repaired.

T' next day, ya bilge rat, matey, it was launched on a A10-3T again in a park with 0.25oz additional lead. Avast, me proud beauty! Again it was unstable with minimal damage. Well, blow me down!

Two days later, shiver me timbers, me hearties, it be launched on a A10-3T again with a total o' 0.69oz of weight. Well, me hearties, blow me down! Marginally unstable, it deployed t' parachute at ~10ft and was recovered with no damage. Avast! Ahoy!

(Scratch) V-32 Since the incrementally added weight resulted in increasingly wimpy altitudes in RockSim, an executive decision was made t' replace 4 o' t' 0.125" fins with 0.25" fins. Followin' this transplant operation on 4/9/05, shiver me timbers, ya bilge rat, it was launched on a 1/2A3-2T with no improvement over t' previous marginal stability and late deployment. Aye aye! At this launch wind dragged t' rocket across some asphalt, severely damagin' many o' t' fins. Arrr!

Since more fin was needed, ya bilge rat, t' final version was built with 4 new fins sized at 1.75" x 0.5" replacin' t' earlier scaled up 0.25" fins. Avast, me proud beauty!

On 4/15/05, ya bilge rat, a stable flight be achieved. Blimey! Too bad t' A10-3T delay be more like 6 seconds. Begad! Lawn dart. Begad! Oh well, shiver me timbers, me bucko, a little glue and tape and it's ready t' go again. She doesn't look bad for an old test sled.

Recommended motors are A10-3T and 1/2A3-2T. Arrr!

Summary:
Kudos t' Mr. Blimey! Melville Grant Boyd for a very cool concept.

(Scratch) V-32 PROs: This is a rocket that gets a tremendous amount o' attention at t' club launch and is easy t' fly. Avast! Ya scallywag! It's fairly hard t' damage because o' its size. Begad! It is cheap to experiment on.

CONs: It's small and won't get t' great cracklin' roar o' a mid or high power rocket.

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