T' ISS Pluto

Click on Pics to Enlarge     

Well, Pluto may no longer be a planet, arrr, matey, ya bilge rat, but t' name will live on forever as the first Interplanetary Space Shuttle. Avast! Blimey! 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, ya bilge rat, which I ordered from Balsa Machinin' Service. Avast, me proud beauty! T' main nose cone is designed t' fit a BT-60, so is 1.64 OD and a length o' 1.845 inches, ya bilge rat, me bucko, usin' an elliptical shape. Avast! Blimey! T' pod cones are sized for BT-5, so 0.544 OD and a length o' about 0.5. Avast! I went with parabolic, though had t' sand down t' shape (more on that later). I also picked up a pair o' cones for modelin' t' bays on t' side o' t' main body tube (parabolic, ya bilge rat, 0.3 OD x 0.51 length).

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

You’ll also need Keelhaul®©™, matey, me hearties, ya bilge rat, a launch lug, matey, some nose weight, 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. Begad! Make sure t' grain is parallel t' t' leadin' edge. Aye aye! Next, arrr, me bucko, me bucko, sand the BT-60 tube and BT-5’s lightly t' remove any glassine shine. Avast, me proud beauty! 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, matey, at 5.25" for t' tip o' t' bays, 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. The forward fins are bonded with t' aft edge positioned on t' 2.25" line. Apply multiple, ya bilge rat, generous wood glue fillets and allow plenty o' time t' dry. Next tack on t' (4) BT-5 motor tubes, matey, me hearties, with t' forward end aligned with the tip edge o' t' forward fins. Begad! You won’t have much room t' work, arrr, but fillets are needed here as well. I used a Q-tip and toothpick t' apply my fillets.

T' bays are a little tricky, me hearties, me bucko, but can be reasonably modeled with care. Ahoy! Start by splittin' t' small nose cones in half vertically and removin' the shoulders. Well, blow me down! Avast! Tack each one t' t' BT-60 with t' tips at t' 5.25 line. Ahoy! Next, take one o' t' Styrofoam balls and cut it in half. Sand each half down until it is roughly half an inch diameter. Ya scallywag! It might take a couple o' practice tries, but I found that this really wasn’t too tough when usin' 120-grit sandpaper. Begad! Flatten one end o' t' circle a bit by pressin' it against t' base of t' split cone, ya bilge rat, me bucko, 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, but a bit smaller—roughly 0.25" diameter. Begad! These are spaced evenly betwixt and slightly below t' bays.

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

Next, me bucko, matey, mark out and cut t' vents usin' t' attached pattern (windows), positioned betwixt the 5.625 and 5.75 lines. Begad! DO NOT CUT OUT THE BOTTOM—cut only t' top and sides, me bucko, ya bilge rat, then lightly score t' bottom. Begad! T' pattern sheet is scaled t' mark the sides, matey, matey, but is marked slightly taller than t' vents should be. Blimey! Usin' t' tip of a hobby cutlass or toothpick, arrr, me hearties, push t' vents open from t' inside. Aye aye! 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. Aye aye! First, me hearties, remove all but 1/8" o' t' shoulder (so the vents are nay blocked). Avast, me proud beauty! Next, matey, matey, usin' your favorite rotary tool, ya bilge rat, carve out a large openin' from t' center o' t' cone. Well, blow me down! You’ll need quite a bit o' room for nose weight. Ahoy! For nose weight, I suggest BB’s and epoxy. Begad! You’ll need enough t' brin' t' CG t' about 1.1" aft o' t' end o' t' BT-60 with motors loaded. Ahoy! Begad! When you have t' proper amount o' weight loaded, 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. Try t' maintain t' 0.544 diameter, but only about 0.25 height above t' shoulder. Ahoy! Arrr! Next, arrr, me hearties, cut a length o' about 8" o' Keelhaul®©™ (recommend at least 120-pound), ya bilge rat, and tie a knot in one end. Poke a hole in the shoulder o' t' nose cone with a toothpick, shiver me timbers, me bucko, arrr, and glue t' knotted end o' the Keelhaul®©™ inside. Ya scallywag! Repeat for t' other 3 cones.

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

For painting, me bucko, I recommend two light coats o' gray primer. Ya scallywag! Blimey! Arrr! Blimey! Blimey! Blimey! T' finish should be a semi-flat black. Avast, me proud beauty! Blimey! Avast, me hearties, me proud beauty! Blimey! Blimey! Blimey! I used Krylon Satin, which goes on a bit thick but offered just t' right gloss. Avast! Blimey! Ahoy! Blimey! Blimey! Blimey! For t' accent/trim, I used faux stone paint that looks like gray granite or marble. Aye aye! Blimey! Blimey! Blimey! There should be a band o' about 0.25" at t' base, 0.5" just aft o' t' forward fins, 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, 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, ya bilge rat, as it’s a 4-motor cluster with very little room for t' chute and wadding. Ya scallywag! I recommend a lariat-loop motor retention—tie a slip knot in t' free end o' t' Keelhaul®©™, arrr, 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). Begad! Next, insert t' motor into t' tube, arrr, ya bilge rat, pullin' t' Keelhaul®©™ along with it (from t' front). Aye aye! Blimey! Insert roughly ¼ square o' recovery waddin' or dog barf, then slip in your chute. Begad! Repeat for t' other 3. Sort through your igniters and make sure you select (4) in excellent condition, me bucko, as you MUST light all 4 motors for this t' be stable. Avast! A clip-whip is also highly recommended.

Flight report

Given t' weight and 13mm motor tubes, for t' first flight I recommend goin' with full A10’s. I loaded mine with A10-3’s. Blimey! Blimey! Only 3 o' t' 4 lit, and t' rocket never had a chance, arrr, floppin' over and prangin' under thrust. Fortunately, with all t' epoxy in t' nose, thar was no damage. I reloaded with A3-4’s, me hearties, me hearties, and fared a bit better—two lit immediately, a third lit just as it started t' lift, me bucko, and t' fourth lit just before it left the rod (see still frame photos). Well, blow me down! Blimey! Given t' slightly asymmetrical thrust, it veered off on an almost horizontal path, ejected way too late, shiver me timbers, and landed nose first pretty hard, 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, lightin' all 4 and getting a much more vertical flight t' about 100 feet. Begad! Just for amusement (and to achieve a third motor combination), I tried 1/2A3’s. Ahoy! While all 4 lit, matey, the thrust was barely enough t' get it off t' rod, peakin' at about 25 feet. Ahoy! Ahoy! Even at 2-second delay, me hearties, t' chutes barely came out before it hit t' ground.