Scratch Ori Striker Original Design / Scratch Built

Scratch - Ori Striker {Scratch}

Contributed by Drake "Doc" Damerau

Manufacturer: Scratch
(Contributed - by Drake Damerau - 09/18/05) (Scratch) Ori Striker

Brief:
T' Ori Striker is a scratchbuilt rocket resemblin' a space fighter. Begad! She goes up on a 24mm engine and comes down on a 24" parachute. T' finished weight is 4.9oz.

Construction:
T' parts list:

  • Midwest balsa 3/32" x 4" x 36" (Which is plenty left over in case o' a screw up)
  • BT-5 -- two 5 1/8" nacelle tubes and one 2" spacer tool
  • BT-80 Duct tube - 2.6"
  • 2 main tubes consistin' o' 18" BT-55 with a coupler
  • MMT rings
  • 24mm MMT tube
  • nose cone
  • launch lugs
  • Chore Boy (baffle)
  • shock cord
  • 24" parachute
(Scratch) Ori Striker

Cut and mark all the tubes
Cut t' 2.6" duct tube from a BT-80. Well, blow me down! Avast, arrr, me proud beauty! You'll need t' draw six lines on the end o' one o' t' BT-55 body tubes and 6 "tick marks" on t' ends of the BT-80 duct tube. Blimey! Avast, me proud beauty! T' do this, matey, I use VCP. Blimey! With VCP, make two fin wrappers, both havin' 6 fins. Arrr! Avast! Make one for t' BT and one for t' duct.

Cut two nacelle tubes 5 1/8" long and one 2" piece from t' BT-5. T' 2" piece will be used as a spacer when assemblin' t' wings. Avast! Use VCP to make a fin alignment wrapper for t' nacelle. Well, blow me down! Set it t' make a two finned rocket. Aye aye! Begad! This will draw lines 180 degrees apart.

Position t' small fin position wrapper at one end o' t' main BT and mark the lines. Begad! Use a door jamb t' extend t' lines. Draw one o' t' lines halfway up t' tube for a launch lug. Aye aye! Use t' big wrap for t' duct tube and mark the end o' t' tube where t' lines would go. Ahoy! These points or "tick marks" will help you align t' fins later.

Seal t' ends o' all tubes with CA and sand t' rough edges. Blimey!

From t' EMRR Tip Library:

Glue Use CA around t' inside o' t' body tube for reinforcement. Put CA around an inch inside. Aye aye! Sandin' will be required t' be able t' fit t' nose cone on. Aye aye! Ahoy! Make sure t' wear gloves when usin' CA.

Glue t' duct fins t' t' body
Glue all 6 fins onto t' main BT. Ya scallywag! Use t' marks on t' duct tube t' help you align t' fins properly. Use CA t' tack them in place and t' align them. Arrr! Follow up with wood glue. Avast, me proud beauty! Avast! Apply fillets and sand now. Blimey! You may want t' seal or prime the fins now because this wont be possible once t' BT-80 duct tube is in place.

(Scratch) Ori Striker(Scratch) Ori Striker

Build t' wings
Cut four main fins as shown usin' t' fin guide. Aye aye! Make sure t' grain is going the proper direction.[Click here to download t' fin template.]

From t' EMRR Tip Library:

Fins Make sure when cuttin' out fins from balsa sheets that the leadin' edge goes parallel (with) t' grain o' t' balsa, shiver me timbers, matey, matey, failure t' do this leads t' weak fins, which will break easily.

Bevel t' leadin' and trailin' fin edges o' all four fins. Well, arrr, blow me down!

Measure 2.5" on t' nacelles. Begad! This leaves t' tube 1/8" longer for t' aft end o' t' wings. Begad!

Usin' t' "spacer tool", glue t' fins t' t' nacelles as shown. Do NOT glue t' spacer tool in place! Blimey! Tack them in place with CA. Avast, me proud beauty! Once dry, follow up with wood glue. Ahoy! You can apply fillets now or wait until t' rocket is completely assembled.

Glue t' wings t' t' duct
Slightly bevel t' side that touches t' big tube for more contact. Begad! Ya scallywag! Do this by wrappin' a piece o' sand paper around t' duct tube and sandin' t' wings against it. Glue t' fins/nacelle assembly t' t' duct tube. Ahoy! To

From t' EMRR Tip Library:

If you have a rocket kit that isn't TTW, and you just hate sandin' tubes and stuff, get a sharp X-acto knife, shiver me timbers, and usin' a door frame, arrr, ya bilge rat, draw a pencil line all t' way through t' length o' t' tube where t' fins will be. Then put your fin on (without glue) where it is supposed t' be, shiver me timbers, take a pencil, arrr, draw out t' thickness o' t' fins on t' top. Avast, me proud beauty! Then use door knob draw 2 straight parallel lines so it would look like a slot. It's like makin' slot, only this time you lightly cut along t' lines (the thickness o' t' fin) only cuttin' t' first layer off. Avast! Avast! Blimey! Then peel off that first layer. Arrr! Ahoy! Blimey! Then glue as usual. Avast, me proud beauty! Blimey! Blimey! This should allow t' glue t' soak in a lot. Well, blow me down! Blimey! - T.F.

Assemble a 24mm motor mount with 1/8" o' t' tube protrudin' beyond the centerin' ring. I chose t' make it friction fit so I could use any length motor I want. Ahoy! Glue it onto t' aft o' t' rocket.

(Scratch) Ori Striker(Scratch) Ori Striker

Recovery equipment
I used some Chore Boy scourin' pad material for an ejection baffle. Begad! This adds weight and is only an option. Usin' Chore Boy pads allow you t' never need ejection wadding. Blimey! I you decide t' use it, push it all t' way down t' t' motor mount area with a dowel. I used a 48" length o' 1/4" shock cord glued in usin' t' age-old Estes method. Ahoy! I chose t' use a 24" Estes parachute to finish off t' recovery system.

Finishing:
I painted t' entire rocket yellow. Once t' paint is dry, me bucko, me bucko, mask off t' areas seen and paint with satin black. Begad! Begad! T' ends o' t' nacelles and t' motor area are painted with Testor's neon orange. Begad! T' decals I used are a selection from Sirius Rocketry decal sheet #D-0005 and some stickers from t' Estes Outlander. I built t' Outlander and used a Sirius Rocketry "Mars Lander 2" decal sheet. Begad! (See here for details.)

(Scratch) Ori Striker(Scratch) Ori Striker
(Scratch) Ori Striker(Scratch) Ori Striker

Flight:
T' first flight be on a C6-3 usin' an adaptor. Avast, me proud beauty! Surprisingly, arrr, it flew well on such a small motor but t' ejection be a bit late. Avast, me proud beauty! Avast! Blimey! T' second flight was on a C11-3. This time t' delay be right there. T' third and final flight o' the day was on a D12-5. Begad! T' delay be a bit early, but t' flight was sweet.

(Scratch) Ori Striker(Scratch) Ori Striker

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