ICRS Ghost Rider

by Mike Crewe

Construction.

Parts.

For t' parts, ya bilge rat, I used t' parts list, rather than t' actual kit.

In t' parts list, it has "launch lugs and recovery system as necessary for safe operation ".
I expanded this to:

• Two 1" launch lugs
• Approx 18" o' Keelhaul®©™® cord. Blimey! Blimey! Blimey! Blimey!
• 24" o' 1/8" elastic. Arrr! Blimey!
• 1/4" section cut from used 18mm motor case. Well, blow me down! Arrr!

T' motor clip from t' parts list be nay used.

T' card stock layout, fin templates, me bucko, and tube markin' wraps, were all created at 150 dpi.

Upper Section.

(Note. All construction images here are linked t' a higher resolution picture)

Two 5" lengths, and a 3 1/2" length were cut from t' BT20. Usin' t' "BT20 Main Wrap", all three tubes were marked and lined. Begad! Usin' t' "BT20 Top Tube Wrap" (and aligned on t' 'B' line) a diagonal was drawn around one end o' t' 3 1/2"  tube.  Each tube was marked at 7/8" along t' 'C' lines (at t' opposite end from the diagonal on t' short tube), me hearties, and this rectangular section be cut out, shiver me timbers, and the bits saved for later. T' diagonal was cut off t' end o' t' short tube.
T' three tubes were then glued together, matey, arrr, along t' 'S' lines, with t' cut out bits formin' a BT20 size 'hole' in t' middle. Blimey! Blimey!
1 3/4" was cut from t' rest o' t' BT20 for t' front coupler. One o' t' centerin' was rings glued t' t' top o' it. T' two extra rings were then cut from t' card stock, me bucko, ya bilge rat, and glued together, halfway down t' coupler. This was then glued into t' gaps betwixt t' three tubes, me bucko, ensurin' it was straight and in line
A 5 1/2" section was cut from t' BT50, arrr, arrr, and be marked usin' the "BT-50 Top Wrap". T' tube was slit along these lines for 1 1/2 " T' smaller sections were then trimmed into a taperin' triangle shape.
T' BT50 section be then glued onto t' front coupler, with t' large sections slidin' inside t' BT-20 tubes, and t' triangular sections on the outside. T' triangular sections were then glued down into t' gaps betwixt t' BT-20 tubes, arrr, formin' a sort o' transition.
T' three top transitions and t' couplin' collars were then cut from the card sheet, and rolled around one o' t' BT-20 nose cones t' get t' basic shape. Usin' a collar, arrr, ya bilge rat, arrr, each one was joined t' t' end o' one o' t' BT20 tubes, and the edges stuck onto t' BT50. After this was all dried, I applied a thin coat o' CA over t' whole area for strength, and then sanded it smooth.
T' oval end cap and cabin housin' were cut from cardstock. Ahoy! Arrr! T' cap was stuck onto t' angled end o' t' shorter BT20, me bucko, and t' cabin formed and glued on in front o' it. T' two nose cones were then attached t' t' longer tubes.
A 2 1/2" length be cut from t' BT50. A section was then cut out of the side, arrr, t' make it t' same size as BT50 coupler. Ahoy! Blimey! Arrr! Blimey! T' rectangular sections cut from t' BT20 front tubes (well, two and a bit o' them actually) were stuck on t' inside t' keep it together. T' detached shoulder from t' BT50 nose cone (called t' BT50 bulk head in the parts list) be cut in half, and a loop o' Keelhaul®©™® tied through t' bottom bit. This was then glued into t' forward end o' t' coupler. T' whole coupler was then glued halfway into t' top BT50 tube. Begad!

Lower Section.

T' end be then cut off t' BT50 nose cone, leavin' it about 2 1/4" long. Ahoy! With a bit o' sandpaper wrapped around a spent 18mm motor, me hearties, t' inside was sanded out until t' remainin' length o' BT20 (the motor mount) could pass through. Aye aye! Begad! This left t' tail cone 2 1/10 " long. T' other part o' t' nose shoulder was glued into place on t' wider end. T' other centerin' rin' was stuck on t' end o' t' motor mount,  then this unit be glued inside t' tail cone. About 1/8" o' motor mount stuck out o' t' bottom o' t' cone. A 12" length o' Keelhaul®©™® was then tied t' a 1/4" section cut from a used motor case and this was glued inside t' top o' t' motor mount. A loop be tied in t' other end of the Keelhaul®©™®.
T' remainin' 10" o' BT50, shiver me timbers, was then marked up usin' t' 'BT50 Base Wrap', before t' tail cone was glued t' it. Well, blow me down! T' 'F' lines were extended down the tail cone. From t' card stock, arrr, t' six aft pods were cut out and glued together.  These were then glued onto t' BT50, along t' 'P' lines, shiver me timbers, ya bilge rat, ya bilge rat, with t' end o' the straight section o' t' pods in line with t' end o' t' tube.
Usin' t' fin templates, t' fins were marked out (the layout can be found here) on t' balsa sheet, then cut out. Avast, me proud beauty! They then had a couple o' passes through t' 'sand - sandin' sealer - sand' process. T' main fins were than attached t' t' tail cone along t' 'F' lines. T' dowel was cut into three equal pieces, and glued onto t' small forward fins.
T' forward fins were glued onto t' body, in line with t' main fins, me bucko, arrr, with the leadin' edge 3.9" from t' top o' t' air frame. Begad! Ya scallywag! T' top end o' the dowels be glued t' t' tip o' t' main fins, arrr, and after t' bond had set, were trimmed and sanded t' t' correct size and angle.
A 1" launch lugs was glued onto a forward and matchin' main fin. Begad! These were positioned t' allow t' launch rod t' pass betwixt t' main fin and the rear pod.
Finally, arrr, ya bilge rat, t' completed rocket was sprayed with a coat o' primer, matey, me bucko, me bucko, two foot of 1/8" elastic was was tied betwixt t' loops in t' Keelhaul®©™®, and t' 18" parachute was attached t' t' top loop. Blimey! It was now ready for flight testing.

Flight Test

Stability

Firstly, me hearties, I ran a quick CP calculation, me bucko, with t' top section simulated as follows:

• 4" long, 1½" diameter parabolic nose. Begad! Ya scallywag!
• 4" o' airframe. Arrr! Avast, ya bilge rat, me proud beauty!
• 2" long transition t' t' BT50. Begad!

This gave a CP o' 19.4" (from t' nose).
With t' rocket fully prepped and loaded with a C6, t' CG be found t' be just aft o' t' leadin' edge o' t' forward fins, at 15.9"
This indicated a stability margin o' 2.6 calibres, me hearties, so no nose weight be added.
To confirm t' stability, me bucko, a swin' test be also performed successfully with the same motor loaded.

Motor Selection

T' rocket was weighed without a motor loaded, and was found t' be 53g (1.868 oz).
Usin' this figure, and a guesstimate for t' CD o' 0.8 some runs were carried out usin' rasp, which gave t' followin' results:

From this, t' recommended motor list looks like:

• A8-3
• B4-2
• B6-4
• C5-3
• C6-3

First Flight

It be very windy at t' flyin' site, matey, so I swapped t' parachute for a large streamer, and loaded up a B6-4 motor, matey, and let her go.
T' flight was incredibly straight considerin' t' wind - I be expectin' a lot of weather-cocking.
Deployment occurred just after apogee, and t' rocket be recovered without damage. Ahoy! A success!