Scratch Bad to the Bone Original Design / Scratch Built

Scratch - Bad to the Bone {Scratch}

Contributed by Ray King

Manufacturer: Scratch
(Contributed - by Ray Kin' - 07/06/08)

Brief:
Bad t' t' Bone is me submission t' t' “Box o' Stuff” contest. Blimey! This rocket flies on a 24mm engine. Upon ejection t' rocket separates into 4 components: main body, upper body, escape pod, ya bilge rat, shiver me timbers, and internal payload. T' main and upper body sections deploy parachutes, shiver me timbers, t' escape pod is a glider and t' internal payload is helicopter recovery.

Parts

Construction:

  • 1. Begad! Begad! 1 - Big Bertha Nose Cone
  • 2. Ya scallywag! Avast! 1 - Plastic BT 5 Nose Cone
  • 3. Avast! 1 - Estes Cosmic Cobra Nose Cone with Helicopter Blades
  • 4. 1 - Birthday Horn
  • 5. 1 - 7.0” BT60 Tube
  • 6. 1 - 13.5” BT56 Tube
  • 7. 4 - 3.0” BT50 Tube
  • 8. Ya scallywag! Arrr! 1 - .5” Wide 3.85” OD Tube
  • 9. 2 - .5” Wide Tongue Depressors
  • 10. Avast! Blimey! Begad! Blimey! 2 -1” long launch lugs
  • 11. 4 - .125” Diameter Bamboo Sticks
  • 12. Begad! Blimey! 6 - Wooden Tooth Picks
  • 13. Ya scallywag! 1 - BT5 Plastics Fan Can
  • 14. 18” 150# Keelhaul®©™® Shock Cord
  • 15. Well, blow me down! Ya scallywag! 24” 1/4” Elastic Shock Cord
  • 16. Avast, me proud beauty! 1 - Small Styrofoam Glider
  • 17. Aye aye! Blimey! 2 – BT 56 t' BT50 Centerin' Rings
  • 18. 1- 3.0” 24mm Engine tube
  • 19. Begad! 1/8” Balsa
  • 20. Begad! Blimey! 1 oz. Begad! Blimey! Nose Weight (BB’s)
  • 21. 1 - Bad t' t' Bone Decal
  • 22. Blimey! 1 - Sparkle/Glitter Decal

UnpaintedConstruction:

Engine Mount:

Start with 3.0” – 24mm engine tube; markin' t' centerin' rin' location roughly.75”-1.0” from each end. Avast, me proud beauty! On t' top centerin' rin' notch it slightly for t' Keelhaul®©™® shock cord. Now tie t' Keelhaul®©™® cord around t' center o' t' tube and mount t' centerin' rings. Ahoy! Make sure t' pull t' shock cord through t' notch and push up tight t' upper centerin' ring. Aye aye! Begad! I would recommend puttin' a bead o' glue directly over t' top o' t' cord at t' joint betwixt tube and centerin' ring.

Fins Construction:

T' fins are cut from 1/8” thick balsa per template A. T' leadin' edge should be rounded.

Launch lug assembly:

There are 2 – 1/8” launch lugs each 1 inch long. Avast, me proud beauty! One attaches t' t' main body assembly betwixt the mock engine tubes and t' second attaches t' t' upper body tube assembly.

T' launch lugs require standoffs. Begad! Cut 2 standoffs from 1/8” balsa. Begad! Ya scallywag! T' main body launch lug standoff should be cut t' .25” X 1.0”. Begad! T' upper tube assembly launch lug standoff should be cut t' .060” X 1.0”. Each standoff is mounted t' t' lugs usin' 5 minute epoxy.

Main Body Transition:

T' main body transition is made from t' Big Bertha nose cone. Drill a .25” hole in t' center o' t' nose cone; now drill a .5” hole enlargin' t' hole. Ahoy! Next, shiver me timbers, ya bilge rat, I use me Dremel tool t' enlarge t' hole t' fit t' main body tube. Do this carefully and make sure you do this evenly. Avast! T' hole needs t' remain in t' center o' t' nose cone.

Main Body Tube Assembly:

Start with t' main body tube (BT56) and cut it to13.5” length. Mark t' tube with 4 lines 90 degrees apart. T' lines should run t' length o' t' tube. Well, blow me down! Ahoy! They are for t' mock engine tubes, fins, me hearties, and rin' supports. Blimey! Now add a 5th line exactly betwixt 2 o' t' other lines. Aye aye! Aye aye! Mark this line as t' launch lug line. At this point t' main body tube should now have 5 lines. Blimey! Now draw a line around t' tube perpendicular t' t' 5 lines. Ahoy! This line should be 2.5” from one end o' t' tube (mark this as t' top o' t' tube).

Now, mark t' 4 - 3.0” BT50 tubes with lines 180 degrees apart. Aye aye! Next, me hearties, shiver me timbers, mount these 4 tubes (mock engine tubes), one on each o' t' lines on t' main body tube. Begad! Arrr! T' engine tubes should mount flush with t' bottom o' t' main tube. Ahoy! Make sure they are straight and align with t' main body tube. Blimey! Once dry add generous fillets betwixt t' body tube and mock engine tubes – I like t' use 5 minute epoxy for this.

Next, matey, matey, t' fins can be mounted on each o' t' engine tubes. Well, blow me down! Avast, me proud beauty! Align t' fin t' be flush with t' bottom o' the tubes. Avast, me proud beauty! See pictures t' ensure they are installed in t' correct orientation. Blimey! Once dry add generous fillets betwixt the fin and t' tube.

Next, arrr, mount t' main body tube transition. Avast! Slide t' transition on t' t' tube in t' correct orientation. Slide it down t' t' mock engine tubes. Avast, me proud beauty! Now apply a liberal amount o' glue above t' line (I used 5 minute epoxy) and slide the transition up until it is even with t' tube. Arrr! Well, blow me down! Make sure t' transition is straight, otherwise t' upper tube assembly will nay be straight.

Now take t' tongue depressor; cut t' radius ends off and cut it into 4 -1 inch lengths. Aye aye! These can now be mounted on t' 4 lines in line with t' fins. Aye aye! T' mount t' tongue depressor directly under t' transition and once again when dry add generous fillets usin' 5 minute epoxy.

Last but nay least – mount t' engine tube assembly in t' main body leavin' about .5” o' t' engine tube stickin' out t' end o' t' rocket. Make sure t' Keelhaul®©™® shock cord extend out t' top end o' t' tube. Avast! Blimey! Attach an additional elastic shock cord and 18” plastic parachute to t' Keelhaul®©™® shock cord.

Party Horn Upper Body Tube Assembly:

T' upper body assembly is made up of: party horn, plastic fin can, nose cone, shiver me timbers, 5 tooth picks, launch lug assembly and BT60 tube.

Start by mountin' t' plastic fin can t' party hornpipe with 5 minute epoxy. Also, use 5 minute epoxy t' fill in the top gap betwixt t' fin can and t' party horn. Blimey! Ahoy! Now, me hearties, take t' nose cone and cut off t' area that would typically go into a body tube. Ahoy! Next, drill a .125” hole thru t' very tip o' t' nose cone. Ahoy! I have found this is typically easiest t' drill from t' inside out. Now, mount 1 o' t' tooth picks in this hole with 5 minute epoxy. Arrr! Avast, me proud beauty! I also, shiver me timbers, shiver me timbers, spread a thin coat o' epoxy on t' t' tooth pick t' strengthen it as much as possible. Ya scallywag! Note: it is very likely this tooth pick could break on recovery so you may choose nay t' add this feature – I believe t' aesthetics are worth some maintenance. Now, matey, t' nose cone can be mounted t' party horn.

After t' fin can and nose cone have dried mount one tooth pick on t' end o' each fin – see pictures.

T' final step is t' attach t' shock cord. I used t' traditional Estes approach for this on this section o' the rocket. A 12” plastic parachute is attached t' t' shock cord.

Center Rin' Assembly:

Mark t' 3.85” OD rin' as if you were mountin' 4 fins 90 degrees a part on it. Well, blow me down! Now, ya bilge rat, cut 4 pieces of 1/8” balsa per Temple B. Avast! These can be glued on each line in t' same orientation. T' fin support rods will mount to each o' these.

NOTE: Read t' paintin' and finishin' section before doin' this step. Avast, me proud beauty! Arrr! Now mount t' large rin' t' t' ring supports on t' main body assembly. Avast, me proud beauty! Aye aye! Once this is dry t' bamboo support rods can be mounted t' t' edge o' t' fins and rin' adapters.

Escape Pod Assembly:

T' escape pod glider is a Styrofoam glider similar t' those used in on t' FlisKits Tri-Glide rocket. Arrr! T' only thin' required is t' add a tooth pick t' secure t' glider durin' lift off. Begad! Cut a tooth pick in half and coat with Styrofoam safe CA. Begad! T' tooth pick should be placed in t' center o' t' front support o' t' glider. Ahoy! Durin' launch the toothpick will rest inside launch lug o' t' plastic fin can at t' top o' t' rocket.

Payload Assembly & Painting:

T' payload be t' Estes Cosmic Cobra nose cone with helicopter recovery so no real assembly was required – only addin' t' rubber bands – see flight prep.

Finishin' this required sandin' t' moldin' partin' line and until t' entire nose cone be smooth. I applied 2 or 3 coats o' automotive gray primer sandin' in betwixt each coat with 400 grit sandpaper. Well, blow me down! Next, I applied a Hot Pink Pearl (Model Master #4643) after this dried. Ahoy! I masked t' stripes and applied gloss black (Model Master #4695).

Finished Paintin' & Decals:

T' Estes t' Estes Cosmic Cobra nose cone really inspired t' color scheme o' this rocket – I liked on the pink blades really contrasted with t' black nose cone. Avast, me proud beauty! Blimey! I painted t' entire rocket prior t' addin' t' center rin' and rin' supports. I would highly recommend this approach. Avast, me proud beauty! Avast! Blimey!

First, shiver me timbers, I filled all t' balsa components, sanded and filled until they were completely smooth. Aye aye! Avast! Next, me bucko, ya bilge rat, me bucko, I applied a couple o' coats o' primer sandin' after each. I painted t' entire rocket Hot Pink Pearl (Model Master #4643). Begad! Begad! After maskin' t' mock engines I applied t' Cadmium Yellow (Model Master #4611) t' t' mock engines and t' tooth picks on the upper fin can. Begad! Blimey! Next, I masked and applied gloss black (Model Master – 4695). After t' black had dried for about 48 hours I added t' Bad t' t' Bone decal and t' sparkle decals t' t' upper fin assembly and center ring. Aye aye! The final step be t' apply 3 coats o' Krylon Acrylic Crystal Clear #1303.

Flight Prep:

Prior t' t' first flight I decided t' do t' spin test and had t' add an ounce o' nose weight. Begad!

Payload flight prep is pretty simple; add rubber bands t' activate t' bands when free from a body tube.

T' big question be how t' get t' payload (Estes Cosmic Cobra nose cone) out o' t' upper tube o' t' rocket. Avast, me proud beauty! I decided t' add a loop t' t' upper shock cord roughly 5-6” from t' end o' t' tube (see picture). T' loop wrapped around t' very tip o' t' nose cone; t' thought be that t' shock cord would pull t' payload out when the parachute opened up.

Here is me recommended approach: Prep a D12-3 engine, add t' igniter and tape in place (no launch lug). Well, blow me down! Arrr! Add a handful o' “dog barf” and stuff t' t' bottom o' t' main tube assembly. Now roll each parachute and load the lower assembly parachute and then t' upper parachute both in t' main body tube assembly. Begad! Next, load t' payload into upper tube assembly (hookin' t' tip o' t' nose cone into t' loop o' t' shock cord). Arrr! Avast! Now carefully and neatly stuff the remainin' shock cord into t' main body tube and slip t' upper and main tube assembly together. Aye aye! Ya scallywag! Finally, shiver me timbers, the escape pod (glider) hangs from t' launch lug on t' plastic fin can at t' very top o' t' rocket.

Flights:

I was very pleased with all 3 flights; t' launches were straight even with t' extra mass o' t' glider. Begad! The rocket hit apogee and then ejection. Well, blow me down! Begad! T' glider separated and flew like a champ. Arrr! T' payload started t' spin and although nay as fast as a competition helicopter it was spinning. Blimey! Avast! Next, I saw both parachutes open and drift t' the ground. Aye aye! T' flight o' t' glider was incredible about 70-80 seconds. T' second flight was also very good; however, me hearties, the glider be lost on t' local school – Bummer!! T' third and final flight was also good even without t' glider. Begad! I need t' find out where t' buy more gliders!

Deployment Launch Rod

Summary:

Pros:

T' four recovery pieces keeps you busy watchin' their descent. Avast, me proud beauty! T' escape pod (glider) performed much better then I expected. Aye aye!

Cons:

T' tooth pick at t' tip looks great, me hearties, but broke after t' first flight – I think I will make this a press-in component that can be removed prior t' a flight or is at least very easy t' replace.

Other:
Overall this be a great project – t' “Box o' Stuff” be a bit intimidatin' when all t' parts were laid out on t' floor. Ya scallywag! After, shiver me timbers, comin' up with t' concept, things just seemed t' flow together. I was very please with flights and can’t wait t' buy more gliders. Well, blow me down! Thanks t' EMRR and Todd Mullins for puttin' this contest together. GREAT WORK!!!

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