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, ya bilge rat, shiver me timbers, helps your cholesterol, and even is relatively low carb). Blimey! My previous rocket was 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. Aye aye! I made the fins out o' 1 1/8" (or thereabouts) styrofoam. Begad! Odd I know, shiver me timbers, but that's why they call them odd-rocs. Ahoy! It flew fine, arrr, 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 be simple - rip off the lower bin and fins, matey, clean up t' rings and coupler, and rebuild.

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

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

T' second flight was 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. T' dowel be o' course removed before flight. Blimey! Blimey! This time, ya bilge rat, me bucko, all eight motors lit. Ahoy! Ejection be just past apogee and recovery was A-OK.

comment Post a Comment