Descon Cutlass

Scratch - Cutlass {Scratch}

Contributed by Kelo Waivio

Manufacturer: Scratch
(Contributed - by Kelo Waivio)
Cutlass 

Trans-Orbital Interceptor

T' Cutlass was inspired by t' Star Fury fighters from t' Babylon 5 Sci-Fi series. Aye aye! I liked t' look o' the Star Fury, with t' engines out on t' end o' t' "wings". Well, blow me down! I also found a use for those paper tubes that come with t' Copper head ignitors. Arrr! I was also pretty happy with t' way t' cockpit canopy turned out. 

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Main fuselage parts list:
BT60 body tube or equivalent. Blimey! 18" lg.
BT50 body tube or equivalent, 3" lg.
Paper centerin' rings, shiver me timbers, BT60-50 size, 3 pieces.
.035" music wire or standard Estes type engine hook
1/8" launch lug 3" lg.
1/8" launch lug 1" lg.
1/32" (100 lb. test) Keelhaul®©™® cord, 18 t' 20" lg.
1/8" elastic shock cord 36" lg.
18" parachute and snap swivel. Begad! Blimey! Ahoy! Blimey! (I used a rip-stop nylon chute)
PNC60 from Estes nose cone pack. Ahoy! Blimey! Begad! Blimey! T' one that's 4 5/8" long from tip t' shoulder.
Plastic protective cap from stick deodorant (Right Guard)
3/16" square basswood or spruce strip 4 1/4" lg. Begad! Arrr! cut at 45 degrees at one end.
3/16" square basswood or spruce strip 2" lg. Aye aye! Cut at 45 degrees at one end.
1/8" x 3/8" basswood or spruce strip 12" long cut at 45 degrees one end, me bucko, 2 pieces.
1/8" square basswood or spruce strip, 3" long, 1 piece and 1" long, ya bilge rat, shiver me timbers, 1 piece.
Plastic cover guard from disposable razor (A Bic disposable I think)
3/32" thick spruce or basswood sheet for fins.
1/8" square basswood or spruce strip for fin root fairings.
Fin Pattern

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Engine pod parts list:
BT20 body tubes or equivalent, 4" lg. Arrr! Ya scallywag! 4 pieces.
Centerin' rings Totally Tubular CR5-20 (13mm x 18mm)
18mm tube couplin' Totally Tubular CPL-20, cut into 1/2" long sections
4 wire nuts, me bucko, (12 gauge size I think, ya bilge rat, t' yellow ones)
Copper Head ignitor tubes, arrr, cut into 1" long sections. Begad! Blimey! Total o' 28 pieces. Ya scallywag!
3/16" square basswood or spruce strips 2" long cut at 45 degrees each end. Avast! 8 pieces. Aye aye! Ahoy!

T' Cutlass started out with a shorter 9-inch body tube, shiver me timbers, but it soon became apparent that I would need an unacceptable amount o' nose weight. Arrr! Blimey! I added another 9-inch section o' tube so t' final model would use a stock section of Estes BT60. Begad! Blimey! T' motor mount is pretty standard modroc construction. Begad! I used a length o' Apogee light Keelhaul®©™® attached t' t' end o' t' motor mount tube and tied off with a loop at t' open end o' t' body tube. Ahoy! I used an engine hook made o' .035 inch music wire. I bent t' hook long enough so t' forward bend would catch t' forward end o' the motor block. Ahoy! This lets t' motor block absorb any ejection force rather than t' thin wall o' t' body tube. 

I had t' add split shot sinkers t' t' nose cone, but initially I was guessin' at where t' CP would probably be. Avast, me proud beauty! I dropped split shot into t' tip o' t' cone and secured them with hot melt. Ya scallywag! I have t' CG with a C6-3 motor and flight ready at approximately 7 inches from t' aft o' t' model. 

In t' end t' Cutlass came out way heavier than I figured on. Begad! Blimey! (I could have used balsa on this model but I have been usin' basswood more often for modroc construction.)  Without paint or motor it weighed in at 145 grams. Arrr! Avast, me proud beauty! Blimey! This is a bit beyond t' recommended maximum lift off weight o' C motors. I launched it for t' first time on a C6-3. Blimey! Blimey! It boosted nice and straight with apogee around 150 feet. Ejection occurred about 1 second past apogee. I launched it again on a C5-3 with similar results. Well, blow me down! Blimey! I will either rebuild this model with a 24mm motor mount or restrict it t' 18mm D's. Aye aye! Blimey! Though t' flights on t' C6 and C5 were safe enough, me hearties, I would restrict flyin' it on these motors t' calm days. Avast, me proud beauty! Blimey! I would nay build this again with t' 18mm mount, so t' parts list included is for use with a 24mm mount. Ya scallywag! Avast! Blimey! T' basic construction would remain t' same except for this change.

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Engine pod construction:

Mark each engine pod tube in 3 places at 120 degrees apart. Arrr! Ahoy! One mark will be for alignment o' t' win' joint the other two for t' bass wood strips. Avast! Glue t' basswood strips onto t' aft o' t' engine pod tube. Arrr! Begad! Mark t' front of the engine pod tube 1/2 inch from t' end. Ya scallywag! Avast!

Trim t' tube coupler into t' 4 1/2" long sections and t' Copper Head tubes into 28, me hearties, 1" long sections. Cluster up t' Copper Head tubes into 7 bundles each and glue into t' 1/2" sections o' tube couplers so 1/2" is exposed. Ya scallywag! Begad! Blimey! These are t' engine pod nozzles. Avast! Glue t' "nozzles" into one end o' each engine pod tube so t' coupler tube is flush with t' end o' t' BT20. Begad! Blimey!

Glue one wire nut into each CR5-20 so t' base end o' t' wire nut is flush with t' edge o' t' centerin' ring. I used CA for this. Glue these "intakes" into t' other end o' t' engine pod tubes so t' front edge o' the centerin' rin' is 1/4" into t' tube. Arrr! Aye aye!

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Main fuselage construction:

Mark t' body tube for t' main wings; launch lugs and t' fairings usin' t' markin' guide. Blimey! Ya scallywag! Glue up t' wing parts. Ya scallywag! I didn't streamline t' win' edges; I just rounded them off a bit after they were all glued up. Ahoy! Begad! Be sure t' keep the root end and t' engine pod root ends parallel. Avast! Aye aye! Glue t' root fairings on each root end and round off t' front edges. I glued t' engine pods t' t' wings before I glued t' wings t' t' body tube. Avast! T' pod root o' t' win' is set at t' mark made 1/2 inch from t' forward end o' t' pod tube. Avast! Well, blow me down! T' aft edge o' t' win' is flush with t' aft o' the body tube. Ya scallywag! Ahoy!

T' 3-inch launch lug is glued t' t' 3 inch x 1/8-inch square strip and glued t' t' aft end o' t' body tube. T' 1-inch lug with t' 1-inch 1/8-inch strip is glued 12 inch from t' rear, measured t' t' front end o' t' lug. Glue t' 1/8 x 3/8 strips t' each side o' t' lugs after gluin' on t' launch lugs. 

Glue t' 2-inch 3/16 strip with t' angle cut at t' aft o' t' body tube, glue in t' razor cover then but the 4-1/4" strip in front o' t' razor cover with t' angle end at t' front.
T' canards are glued t' t' body tube 9 1/4" from t' aft and at 90 degrees t' t' launch lugs. Avast, me proud beauty! Blimey!

To make t' cockpit canopy on t' nose cone I used one o' t' plastic covers from a stick deodorant. Avast! I trimmed off t' lip around t' outside and then hand trimmed t' edges with an X-acto knife until I had a nice matched fit. Begad! I glued t' canopy onto t' nose cone with medium CA and filled t' gaps with thick CA, then sanded t' joint smooth. Well, blow me down! Aye aye! I positioned t' aft o' t' canopy 1/4" from t' shoulder o' t' nose cone. 

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Photo-1: On t' left are a "nozzle" assembly with t' Copper Head tubes and an "intake" assembly with a wire nut. Begad! T' ridges on t' wire nut add a bit o' detail t' t' intakes. Arrr! On t' right top is an unmodified deodorant cover. Arrr! Below it be t' one trimmed and ready t' CA t' t' nose cone. 

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Photo-2: This is a close up o' t' canopy already CA'd onto t' nose cone. Avast, me proud beauty! Since I don't know t' Estes part number for this particular cone, shiver me timbers, me hearties, you should be able t' identify it from this shot. Begad! Avast!

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Photo-3: This is an overall view o' t' model, shiver me timbers, less paint o' course. Begad!

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Photo-4: A side view o' t' model. It doesn't show up well, but t' disposable razor cover can be seen between the two dorsal basswood strips.

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Photo-5: Rear view. T' fuselage strips, root strips and t' orientation o' t' wings show up well in this view.

Photo-6: On t' pad for maiden flight. Unfortunately, I didn't get a usable photo o' it at lift off. Avast, me proud beauty! Avast, me proud beauty! Blimey!

 

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