Manufacturer: | Scratch |
Brief:
A simple LPR single stage, motor deployed chute recovered tube fin rocket.
Construction:
1 - 24" x 3" BT, me bucko, 1 24" x 3" BT for fins, me bucko, me bucko, matey, 1 chute, shiver me timbers, 29mm MMT
and 2 CR's, a nose cone, shock cord and a launch lug.
I be asked t' write a review on me scratch built Circle Jerk. Blimey! I hadn't documented any o' t' construction, arrr, matey, so I decided t' build another one, arrr, but this time I documented t' process. Blimey! Avast, me proud beauty!
For both birds I used 3" USR "whitewall" tubin' because o' its thickness. It's twice as thick as any other tubing. I felt that it gives a better appearance t' t' tube fins. Blimey!
I cut all o' me tubin' with a 12" DeWalt compound miter saw. I use a special rippin' blade that has more teeth than most blades. This gives a smooth cut that needs very little work. T' softer paper tubes do fray a little but that is solved by soakin' t' ends o' t' tubes with thin Cyanoacrylate or thinned wood glue. Avast! Avast, matey, me proud beauty! When t' glue hardens, just sand t' ends t' t' finish you need. For phenolic tubes, shiver me timbers, it gives a factory like finish. Avast!
T' first picture shows t' tube bein' cut and t' jig I used. Ahoy! For this
rocket, I made all cuts at a 45-degree angle. Avast, me proud beauty! T' original had just t' forward
cut at a 45 and t' aft cut at a 90. Blimey! I just wanted t' do somethin' different
this time. Avast!
If you use t' same diameter tubin' for t' fins as t' body tube, you will need 6 fins. Avast, me proud beauty! Arrr! All tube fin rockets work this way. (Do t' math) Attachin' the fins is elementary. Avast! Draw a line around t' tube where you want t' forward tip of t' tube fins t' be. Well, blow me down! Put a bead o' glue (I used wood glue) on t' first fin and align it on t' BT. If you lay it on its side on a table they will be parallel t' each other. Avast, me proud beauty! Begad! No more thinkin' will be necessary because the subsequent fins just lay on t' last fin and t' BT. Avast, me proud beauty! For t' next fins, just find where t' tubes touch, me bucko, draw a line and put t' glue there. Arrr! T' final fin will snuggle up betwixt t' last fin applied and t' first fin. Use fillets as you see fit, but they are nay necessary for strength because each fin is glued at 3 points. Begad!
It's tough t' find t' CP on tube fin rockets like this but it's safe to say that its somewhere in t' fin section ;-) Just make sure t' CG is forward of t' fin section with a motor installed. Well, blow me down! Aye aye!
Flight:
For t' original rocket, I used a standard 29 mm motor mount tubes cut t' 6
inches. Avast, me proud beauty! T' centerin' rings (2 o' them) were just 5 ply rings I had laying
around. Avast! Avast! T' 32" parachute and t' shock cord was from a lawn-darted
Aerotech Astrobee D. Well, blow me down! T' nosecone is a 3" PML. Aye aye! Begad! T' launch lug is just a
¼" Aerotech igniter tube. Avast! (OK, yeah I'm cheap) T' final weight is
about 24oz. Begad!
For flying, I always use dog barf and friction fit motor retention. Blimey! She flew straight as an arrow on several F and G motors. Begad! Fun t' fly.
Summary:
This is a quick and easy rocket t' build. Begad! Its different than most tube fin
rockets and draws a little attention. Blimey! Nay countin' t' paint, matey, arrr, it took all o' an
hour t' build.
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