T' ISS Pluto

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Well, Pluto may no longer be a planet, but t' name will live on forever as the first Interplanetary Space Shuttle. T' final version is nay scheduled for completion until 2012 (and has nay yet received funding), but a reasonable prototype can be built from relatively inexpensive materials and flown on the much more common model rocketry hobby motors.

There are a few custom-turned parts for this model, which I ordered from Balsa Machinin' Service. T' main nose cone is designed t' fit a BT-60, shiver me timbers, me hearties, so is 1.64 OD and a length o' 1.845 inches, usin' an elliptical shape. Well, blow me down! T' pod cones are sized for BT-5, shiver me timbers, arrr, so 0.544 OD and a length o' about 0.5. Blimey! Aye aye! I went with parabolic, me hearties, though had t' sand down t' shape (more on that later). Arrr! I also picked up a pair o' cones for modelin' t' bays on t' side o' t' main body tube (parabolic, arrr, me bucko, 0.3 OD x 0.51 length).

Body tube lengths and fin templates can be pulled from t' attached Rocksim file. Begad! Blimey! Begad! Blimey! T' fins really need t' be made from basswood, ya bilge rat, nay balsa, arrr, matey, as they will be subjected t' plenty o' stress both in flight and in recovery.

You’ll also need Keelhaul®©™, arrr, a launch lug, some nose weight, me hearties, arrr, (4) 6" chutes, and several Styrofoam balls (which I picked up from t' nearby national chain crafts store).

Start out by cuttin' out four sets o' forward and aft fins from 3/32 basswood. Aye aye! Make sure t' grain is parallel t' t' leadin' edge. Arrr! Next, matey, sand the BT-60 tube and BT-5’s lightly t' remove any glassine shine. This will dramatically improve t' strength o' t' bond.

Mark t' body tube for four fin lines and t' four bays usin' the template attached.

Next, you’ll need t' mark lines around t' BT-60 at 2.25" for the aft edge o' t' forward fins, me hearties, ya bilge rat, at 5.25" for t' tip o' t' bays, shiver me timbers, then a pair o' lines at 5.625 and 5.75 for t' vents.

T' aft fins are bonded t' t' BT-60 flush with t' bottom o' t' BT-60. Arrr! The forward fins are bonded with t' aft edge positioned on t' 2.25" line. Apply multiple, me hearties, generous wood glue fillets and allow plenty o' time t' dry. Next tack on t' (4) BT-5 motor tubes, with t' forward end aligned with the tip edge o' t' forward fins. Well, blow me down! Begad! You won’t have much room t' work, me bucko, but fillets are needed here as well. Aye aye! I used a Q-tip and toothpick t' apply my fillets.

T' bays are a little tricky, ya bilge rat, but can be reasonably modeled with care. Start by splittin' t' small nose cones in half vertically and removin' the shoulders. Avast, me proud beauty! Tack each one t' t' BT-60 with t' tips at t' 5.25 line. Next, take one o' t' Styrofoam balls and cut it in half. Ya scallywag! Aye aye! Sand each half down until it is roughly half an inch diameter. It might take a couple o' practice tries, but I found that this really wasn’t too tough when usin' 120-grit sandpaper. Begad! Avast, matey, me proud beauty! Flatten one end o' t' circle a bit by pressin' it against t' base of t' split cone, then tack it in place usin' white glue.

T' last detail t' form and bond are t' four porthole orbs, each formed from Styrofoam usin' t' same technique as t' bays, matey, matey, but a bit smaller—roughly 0.25" diameter. These are spaced evenly betwixt and slightly below t' bays.

Once t' Styrofoam parts have been tacked in place, coat them with a thin application o' white glue, brushed on. Arrr! Once t' glue has dried, me hearties, arrr, repeat with one more coat. Avast! Ahoy! This really stiffens t' foam and makes it much easier t' paint.

Next, mark out and cut t' vents usin' t' attached pattern (windows), me bucko, me bucko, positioned betwixt the 5.625 and 5.75 lines. DO NOT CUT OUT THE BOTTOM—cut only t' top and sides, then lightly score t' bottom. Avast! T' pattern sheet is scaled t' mark the sides, but is marked slightly taller than t' vents should be. Usin' t' tip of a hobby knife or toothpick, push t' vents open from t' inside. Avast, me proud beauty! You might need to apply a drop o' thin CA if t' edges are frayed.

T' main nose cone will need to be modified quite a bit. Begad! First, remove all but 1/8" o' t' shoulder (so the vents are nay blocked). Next, usin' your favorite rotary tool, carve out a large openin' from t' center o' t' cone. You’ll need quite a bit o' room for nose weight. Begad! For nose weight, I suggest BB’s and epoxy. Well, arrr, blow me down! You’ll need enough t' brin' t' CG t' about 1.1" aft o' t' end o' t' BT-60 with motors loaded. Avast, me proud beauty! When you have t' proper amount o' weight loaded, me bucko, glue t' cone in place t' t' BT-60.

T' four nose cones for t' motor tubes need t' be sanded down t' a much more blunted circle. Aye aye! Begad! Try t' maintain t' 0.544 diameter, arrr, but only about 0.25 height above t' shoulder. Begad! Next, me bucko, cut a length o' about 8" o' Keelhaul®©™ (recommend at least 120-pound), ya bilge rat, and tie a knot in one end. Well, blow me down! Arrr! Poke a hole in the shoulder o' t' nose cone with a toothpick, and glue t' knotted end o' the Keelhaul®©™ inside. Ahoy! Begad! Repeat for t' other 3 cones.

Attach a 1/8" launch lug somewhere forward o' t' fins, ya bilge rat, shiver me timbers, bein' careful not t' be blocked by one o' t' vents.

For painting, shiver me timbers, I recommend two light coats o' gray primer. Avast, me proud beauty! T' finish should be a semi-flat black. I used Krylon Satin, me hearties, which goes on a bit thick but offered just t' right gloss. Well, blow me down! Arrr! For t' accent/trim, I used faux stone paint that looks like gray granite or marble. Aye aye! Blimey! There should be a band o' about 0.25" at t' base, 0.5" just aft o' t' forward fins, me bucko, and a pair o' 0.25" stripes in front o' t' forward fins. T' fins themselves are also painted gray granite.

Finally, t' (4) motor tube nose cones get painted orange, matey, and if you’re really darin' you can also paint two stripes on each motor tube (orange).

Flight prep is a bit tricky on this, me hearties, as it’s a 4-motor cluster with very little room for t' chute and wadding. I recommend a lariat-loop motor retention—tie a slip knot in t' free end o' t' Keelhaul®©™, shiver me timbers, thread it through the forward end o' t' tube and out t' aft end, and secure t' loop around the motor (the motor will need a little tape rin' at t' nozzle end t' serve as a block). Aye aye! Next, insert t' motor into t' tube, pullin' t' Keelhaul®©™ along with it (from t' front). Avast! Insert roughly ¼ square o' recovery waddin' or dog barf, then slip in your chute. Repeat for t' other 3. Well, blow me down! Sort through your igniters and make sure you select (4) in excellent condition, as you MUST light all 4 motors for this t' be stable. Ahoy! A clip-whip is also highly recommended.

Flight report

Given t' weight and 13mm motor tubes, ya bilge rat, for t' first flight I recommend goin' with full A10’s. Aye aye! Begad! I loaded mine with A10-3’s. Begad! Only 3 o' t' 4 lit, and t' rocket never had a chance, floppin' over and prangin' under thrust. Ya scallywag! Fortunately, with all t' epoxy in t' nose, thar be no damage. Avast! I reloaded with A3-4’s, and fared a bit better—two lit immediately, arrr, a third lit just as it started t' lift, arrr, and t' fourth lit just before it left the rod (see still frame photos). Ya scallywag! Given t' slightly asymmetrical thrust, me bucko, matey, it veered off on an almost horizontal path, arrr, ejected way too late, and landed nose first pretty hard, ya bilge rat, but on soft grass (still undamaged).

First two lit	#3 lights up	Finally got t' fourth

A third attempt on A10’s proved much better, me bucko, ya bilge rat, lightin' all 4 and getting a much more vertical flight t' about 100 feet. Avast, me proud beauty! Just for amusement (and to achieve a third motor combination), I tried 1/2A3’s. Ya scallywag! While all 4 lit, shiver me timbers, shiver me timbers, matey, the thrust was barely enough t' get it off t' rod, peakin' at about 25 feet. Blimey! Begad! Even at 2-second delay, ya bilge rat, t' chutes barely came out before it hit t' ground.