Brief:

This describes a semi-successful plastic model conversion o' a small Revell SR-71 Blackbird kit. Arrr! Blimey! Begad! Blimey! Blimey! Blimey! A 13mm motor mount was added t' t' kit.

Modifications:

This be undertaken as part o' t' EMRR 2006 Rocketry Challenge. Begad! Arrr! It represents me first attempt at PMC.

I chose t' kit for its classic styling, potential for stable rocket powered flight, and apparent ease o' conversion. Begad! Various flyin' rocket versions o' this plane have been available over t' years. A ready t' fly starter set is currently on store shelves. Ya scallywag! Blimey! T' challenge o' rollin' me own, albeit a smaller version, shiver me timbers, drew me t' this one.

Upon openin' t' kit I found it t' be a very simple build, me bucko, consistin' mostly o' an upper an lower fuselage/win' combination. Ahoy! A narrow channel ran from nose t' tail along t' central body, narrowin' at each end.

While an 18mm would offer more thrust t' power a heavy kit, me bucko, t' restrictions o' t' airframe barely lent itself t' a 13mm mount. Arrr! I determined that a Gnome body tube was a nearly custom fit for t' main body channel. Ahoy! Even that small tube didn't fit inside t' kit as shipped.

I used a heat cannon t' soften t' airframe and press it around a length o' copper pipe. This stretched t' central core o' t' ship until t' Gnome tube could be sandwiched betwixt t' two halves. Ya scallywag! I also heated and deformed t' Gnome nose cone t' fit it into t' nose o' t' SR-71.

Once t' rough heat moldin' o' t' airframe was done, ya bilge rat, I used a razor saw t' slice t' SR-71 nose off. Ya scallywag! This would be glued around t' Gnome nose cone t' provide a press fit into t' Gnome tube inside t' aft airframe.

I used Gorilla Glue t' bond t' Gnome tube t' t' upper airframe. Begad! I used Testors liquid model cement t' glue t' airframe together around t' body tube. Begad! Once t' airframe was assembled, some additional spot heatin' with t' heat cannon was used t' fine tune t' fit.

An elastic shock cord was fitted t' t' Gnome tube prior t' sealin' it within t' SR-71. Well, blow me down! Ya scallywag! T' help increase stability, I packed t' nose cone with BBs and plastic model cement.

T' final assembly consisted o' usin' Testors liquid plastic cement t' glue on t' tail fins and engine details. Blimey! Blimey! Blimey! A second launch lug from a Gnome kit was separated from it's rin' and glued t' t' bottom o' t' SR-71 near its center o' gravity.

Construction:

T' base model is a snap together SR-71 Blackbird kit by Revell. Avast! T' that was added a slightly crumpled body tube from a Gnome kit, shiver me timbers, along with t' Gnome nosecone and engine retainer.

T' Revell kit is nicely detailed and contains few parts. Avast, me proud beauty! Blimey! Blimey! That means few seams t' worry about splittin' durin' thrust and recovery.

Flight and Recovery:

This is a very small body tube for any kind o' chute. Avast, me proud beauty! Well, blow me down! T' formin' o' t' tube into an oval t' fit inside t' SR-71 frame further reduced t' useable space. Aye aye! I installed a streamer in t' rocket knowin' it would nay be a gentle landing.

I chose an A10-3T motor. Ahoy! Avast! This is a hefty model for a 13mm engine. Ahoy! A small amount o' cellulose insulation be used t' protect t' streamer.

On t' first flight, shiver me timbers, me bucko, ya bilge rat, t' SR-71 boosted clean off t' rod, got t' about 20 feet, ya bilge rat, me bucko, performed a couple o' tail over nose flips, then kicked out t' engine before belly floppin' in t' grass unharmed. Well, blow me down! T' waddin' and streamer offered more resistance than t' engine hook.

A second flight with t' engine hook taped t' t' A10-3T engine went almost t' same as t' first flight. There be a seemingly good boost for t' first 20 feet, me bucko, then a couple o' tail over nose flips. Aye aye! Blimey! This time t' model belly flopped t' t' ground and spit out t' streamer in t' grass.

Summary:

This is apparently still a marginally stable configuration. Ya scallywag! Blimey! More nose weight might be t' answer, me hearties, arrr, but that would likely outpace t' ability o' even t' A10 t' loft t' model.

Those two engine nacelles mounted midway out on each win' offer a tantalizin' opportunity for parallel staging. Begad! I am considerin' how boosters could be fit into t' engine nozzles for extra thrust off t' rod.