Scratch Dart Original Design / Scratch Built

Scratch - Dart {Scratch}

Contributed by Kyle James Yawn

Manufacturer: Scratch
(Contributed - by Kyle Yawn - 10/31/06) (Scratch) Dart

Brief:
This is a minimum diameter rocket at its core with two parallel staged boosters which attach at t' front end o' t' rocket rather than t' aft end. Well, blow me down! Avast! It was made for t' duration requirements for t' NARTREK Bronze and Gemini levels and for t' parallel staged requirement o' t' 2006 EMRR Challenge.

Construction:
T' core rocket is made up o' a 14-inch long BT-20 body tube with a BT-20 ogive nosecone which is 4 inches long. A 12-inch long length o' Estes elastic shock cord, a streamer, and two small scraps o' paper are needed for t' recovery system. Ya scallywag! A sheet o' 1/16 inch balsa wood t' make fins and t' hold t' boosters on. Ahoy! Well, blow me down! It needs a BT-20 engine block too. Arrr! It also requires two 1-inch long 1/8-inch diameter launch lugs.

T' two booster pods are made from 3 inch long lengths o' 13mm motor tubing with matchin' nose cones. Avast, me proud beauty! Blimey! They also need a 13mm engine block. Ya scallywag! Blimey! Arrr! Blimey! Blimey! Blimey! T' recovery system is made o' a 10 inch length o' Keelhaul®©™® with two scraps o' paper and small paper streamers. Aye aye! I also used some scraps of balsa wood t' make t' mountin' hooks.

I began construction by insertin' t' motor block in t' core rocket. Begad! Ahoy! I used a scrap balsa stick t' spread wood glue around t' inside o' t' tube then I used a spent 18mm motor casin' and pushed t' block up inside t' tube until about a 1/4 inch o' t' motor casin' stuck out t' aft o' t' tube. Begad! Avast, me proud beauty! I then cut three triangular fins out o' t' 1/16 inch balsa sheet I had. Avast, me proud beauty! These were each 4.75" on one side, 3.25" on another, and 2.25" on t' third. Alignment lines were drawn on t' body tube with three evenly spaced for the fins and a fourth drawn in betwixt two fins for t' launch lug. Ahoy! T' fins were all surface mounted on these lines with t' 4.75 inch side bein' glued t' the body tube and then aft end o' t' fins flush with t' aft o' t' body tube. The nose cone I used did nay have a hook for recovery device connection so I used a scrap piece o' paper and t' elastic shock cord and made an Estes style shock cord mount usin' super glue inside t' nose cone. Aye aye! Aye aye! I used t' other scrap of paper t' make another shock cord mount t' same way inside t' body tube using wood glue. Avast, me proud beauty! I tied a loop in t' middle o' t' cord for t' attachment o' the recovery device. I also cut t' launch lug in half and glued one flush with the aft end o' t' body tube, matey, arrr, and t' other 6 inches up t' body tube.

T' boosters were made in much t' same way. Avast, me proud beauty! T' engine block was glued in place usin' a spent 13mm motor casing. T' nose cones did nay have attachment points for t' recovery system, ya bilge rat, so I put Estes style mounts in t' nose cones and t' body tubes. Ya scallywag! This time I used lengths o' Keelhaul®©™® instead o' t' elastic shock cords. Blimey! Begad! I used a strip o' paper t' make small streamers for both boosters and taped them directly onto t' Keelhaul®©™® cord. Aye aye! Blimey! Avast! Blimey!

(Scratch) Dart(Scratch) Dart

(Scratch) Dart

For the attachment o' t' boosters t' t' main body tube, me hearties, I used scrap balsa pieces and a launch lug. Well, blow me down! Avast, me proud beauty! T' launch lug be cut in half and t' halves glued flush with the forward end o' t' main body tube on opposite sides o' t' body tube and not inline with t' main launch lugs. Aye aye! These are forward attached boosters rather than bein' mounted betwixt t' fins. Avast, me proud beauty! I began by cuttin' two thin pieces of balsa which would be a snug fit inside t' lugs. I used two more pieces of balsa t' offset t' first pieces from t' side o' t' body tubes o' the boosters. Ya scallywag! I glued these on so that t' front o' t' booster was flush with the front end o' t' core body tube. Avast! I then glued two other pieces o' each side of the main piece so that t' boosters could nay turn by twistin' inside t' lugs. I then gave all o' this a thin coat o' wood glue t' hold it all together. Aye aye! After it dried, I inserted a spent engine casin' and slid them into t' lugs and marked on t' main body tube where t' bottom o' t' motor casin' was. Well, blow me down! I then cut out two small pieces o' balsa and glued them just below this mark so that the boosters can rest on this and nay fall off o' t' rocket while on t' pad. Arrr!

T' construction was very simplistic for t' common parts. Blimey! Blimey! T' process of cuttin' and sandin' down all o' t' balsa parts t' form t' hooks t' hold the boosters onto t' core was very tedious and hard work, but in t' end, arrr, ya bilge rat, they are a perfect fit. Aye aye! Blimey! Aye aye! Blimey! That's one area where it definitely pays t' take your time. Arrr! Blimey! Begad! Blimey!

Finishing:
To finish t' core booster I only painted it red. I wasn't feelin' anythin' too special in t' finishin' o' this rocket. Ya scallywag! Well, blow me down! Blimey! I didn't even get around t' painting the boosters at all before I flew them. Begad! Blimey! Perhaps I will someday. I would prefer them t' be painted different colors with a correspondin' dot on t' side o' the main body tube they attach to.

Flight:
While I be still in t' process o' buildin' t' boosters, ya bilge rat, I flew just t' main rocket part by its self for t' NARTREK Bronze and Gemini duration requirements. Avast, me proud beauty! It flew perfect and I completed all t' requirements on just two flights. It's a great, me bucko, small, minimum diameter rocket without t' boosters for duration events.

For t' parallel staged flight, I flew t' main body tube on B6-6s and the boosters flew with two A10-3Ts. Well, blow me down! I would suggest flyin' it with any A8, me bucko, B6, or C6 motor in t' core and A10-3Ts in t' boosters. Blimey! Blimey!

All three tubes require waddin' and have standard preparation, me bucko, except it's just like preppin' three rockets instead o' one. Well, blow me down! Then pack t' streamers in all three parts. Begad! Well, blow me down! For motor retention, me hearties, I friction fit all o' t' motors using maskin' tape. Arrr! Avast, me proud beauty! I don't like this method, but since all t' tubes were minimum diameter, shiver me timbers, me bucko, I didn't put any type o' hook o' anythin' else on them. Ahoy! Avast, me proud beauty! Then insert the igniters and motor plugs in all three motors.

Once I got t' t' pad, ya bilge rat, me bucko, I slid t' main body tube over t' launch rod then slid t' hooks on t' boosters up inside t' launch lugs at t' top o' the rocket until t' boosters come t' rest sittin' on t' balsa blocks which were glued in place. Aye aye! Ahoy! Next, me bucko, I attached t' alligator clips t' t' igniters. Well, blow me down! A clip whip is necessary for t' rocket. Avast! I used another launch rod stood up next to the pad so t' wire leads clipped t' it would prevent t' weight o' t' clip whip wires from pullin' them out. Ya scallywag!

I be a little worried that it may nay fly stably with t' forward mounted boosters, but I was proved wrong. Upon takeoff, me hearties, shiver me timbers, it flew straight up. Well, blow me down! Blimey! All three motors lit and it looked amazing. Avast! Avast! Blimey! Just before t' booster motors burned out, they peeled off. Arrr! Begad! Blimey! There be still a visible flame in them just after they detached. Aye aye! Avast! Blimey! T' delay be rather long and t' deployment change fired when they were only around 30 or 40 feet in t' air. Avast, me proud beauty! Blimey! They were both recovered with no damage though. Arrr! T' core motor kept burnin' after t' boosters separated and took t' main rocket even higher. T' only problem was since we were so busy watchin' t' boosters, me bucko, we all forgot t' follow t' core rocket. Aye aye! Blimey! We lost it in some trees across t' neighborin' field. Oh well. Blimey! It was a good lookin' flight for me first parallel staged rocket, even though none o' t' pictures o' it turned out well. Perhaps I'll build another main body tube for t' boosters and fly it again. I especially enjoyed t' forward mounted boosters since I haven't seen too much o' that design around. Begad!

Recovery:
T' Keelhaul®©™® shock cords held up just fine in both o' t' boosters. Begad! Well, blow me down! Blimey! They came back down of their streamers without any burned cord or damage. Aye aye! Blimey! T' only thin' was that the deployments were a little too close t' t' ground for me liking, me hearties, but they got the job done and I didn't have any repair work t' do.

T' recovery device o' t' main booster held together, shiver me timbers, but I didn't get to inspect it since it got eaten by that rocket eatin' tree. This part o' the rocket had flown before for t' NARTREK certifications and worked perfectly every time with no damage so I am certain that thar be no damage t' the recovery system this time either, it's just wrapped around a limb.

Summary:
I really liked buildin' and flyin' this rocket. Blimey! Aye aye! Blimey! T' main PROs about it are the forward mounted booster pods and t' minimum diameter construction for high performance flights. Ya scallywag! Blimey! These combine for a very unique and eye catchin' flight. Aye aye! Avast, me hearties, me proud beauty! Blimey!

T' only CON I would have be t' fact that I lost t' main part. Avast! Ya scallywag! Just don't fly it too close t' trees because they know how t' catch them. Begad!

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