Scratch Margin of Error Original Design / Scratch Built

Scratch - Margin of Error {Scratch}

Contributed by Dick Stafford

Manufacturer: Scratch
(by Dick Stafford - 6/22/05)

Background
I really love t' 5" Quaker Oats bins (and I like t' contents too - tastes good, arrr, shiver me timbers, helps your cholesterol, arrr, and even is relatively low carb). Ya scallywag! Blimey! Arrr! Blimey! My previous rocket be made out o' three bins (four if you count t' one I cut up for couplers) and used a clear plastic Easter egg for t' nose cone. Ya scallywag! Blimey! I made the fins out o' 1 1/8" (or thereabouts) styrofoam. Avast, me proud beauty! Blimey! Odd I know, matey, but that's why they call them odd-rocs. Begad! Blimey! It flew fine, but I wasn't that happy with t' fins, and was thinkin' about addin' a bunch o' 24mm mounts t' eat some o' the $3.50/pk D12-0s I have been buying. So t' solution was simple - rip off the lower bin and fins, shipshape up t' rings and coupler, matey, and rebuild.

T' Re-build
T' lower coupler be nice and long and included a lower 3/32" ply centerin' ring. Avast, me proud beauty! So, me bucko, I sliped a new bin on part way, leavin' enough spacin' at the bottom for a bunch o' 24mm mounts. Begad! I decided on eight mounts with gaps to clear t' 29mm motor retainers. I plugged t' gap betwixt t' tube, slotted it for three fins, ya bilge rat, ya bilge rat, me hearties, and cut some nice big fins from light, cheap Luan plywood. Well, matey, blow me down! I made t' 24mm motor unit removable, which should help in preppin' t' motors with quickmatch. Ya scallywag! Begad! Here are some pics:

Flight Report
I flew T' Margin o' Error on 11/14/2004 at MDRA's ESL-78. Aye aye! Blimey! It flew on a G80-7 and eight D12-Ps lit usin' quickmatch. Aye aye! Arrr! Blimey! Well, arrr, actually only three o' the D12s lit. Ya scallywag! T' boost was slow and several seconds late due t' t' reduced thrust. Ya scallywag! Blimey! Nevertheless, arrr, it be a good flight. Upon inspection, t' quickmatch was pulled out o' t' unlit motors, me hearties, but had burned at t' pad.

T' second flight be on 12/12/2004 at ESL-79 with a G79-6 and eight D12-Ps. I took more care in tapin' t' fuses t' t' D12s and positioned them usin' a dowel inserted into t' main motor's core. Aye aye! Aye aye! T' dowel was o' course removed before flight. Arrr! Ya scallywag! This time, all eight motors lit. Begad! Ejection was just past apogee and recovery was A-OK.

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