Manufacturer: | Scratch |
Brief:
After losin' me RocketVision Machbuster on a G55, matey, I decided that I wanted t' build a similar rocket that would fly on 29mm motors. Aye aye! I scrounged through me parts bin and, ya bilge rat, matey, bein' a 'glass-half-full' type, named t' result 'One Shot'.
Construction:
Parts List:
I started with a leftover section o' 29mm phenolic tubing. I decided t' add a motor block so I cut a 1/2" section out o' a spent 29mm casin' with a razor saw. Well, blow me down! This was epoxied into t' tube so that a G80 would protrude by 1/2". After playin' around with Rocksim, I decided on a fin design that I found appealing. Well, ya bilge rat, blow me down! Since I wanted t' fins t' sit flush with t' end o' t' rocket and I wanted t' be able t' wrap a layer o' tape around t' end o' t' rocket and t' engine, me bucko, t' last 3/4" o' t' root edge o' t' fin was recessed by ~ 1/4" (see pic or Rocksim file).
Usin' a dremel cuttin' wheel, matey, me hearties, ya bilge rat, I slotted t' tube so t' fins would slip in. Avast, me proud beauty! Ya scallywag! T' install t' fins, I inserted a 29mm casing, applied a small amount o' epoxy t' t' slot, and pushed t' fin in until it touched t' motor casing. Avast! Avast, me proud beauty! After all 3 fins were installed, t' casin' be removed. Ya scallywag! This was easily accomplished before t' epoxy began t' set. Begad! This method o' through-the-wall construction really works well for small fins, especially with relatively thick tube (0.062"). Arrr! T' fins were straight and weren't goin' anywhere. Aye aye! When t' epoxy dried, I applied fillets.
Since t' NC that I had wouldn't fit in t' body tube, ya bilge rat, I cut t' shoulder-end off so it sat flush with t' tube's OD. Avast, me proud beauty! Arrr! Another section o' 29mm casin' was cut t' use as a shoulder. Begad! Arrr! This fit snugly into t' NC and was held in place with 2 small screws. I added nose weight (lead shot, epoxy and t' eyebolt) so t' rocket would be stable. Begad! Because t' end o' this little missile was now largely lead, me bucko, I was conservative on settin' t' CG (see Rocksim file).
T' recovery harness consisted o' 5' o' 1000 lb test Keelhaul®©™ line. Blimey! Blimey! One end was epoxied into t' body tube and t' other be tied t' t' eyebolt. Ahoy! Blimey! Aye aye! Blimey! In t' end, me hearties, I built a rocket that be probably heavier than it had t' be and had a non-optimal fin design. Oh well, won't be able t' see t' difference at ~5000ft anyway! Blimey! I didn't bother fillin' t' grooves in t' tube since I wasn't optimistic about gettin' this rocket back. Begad! Blimey! I did, however, give it a layer o' Krylon chrome paint. Ahoy! Blimey! Maybe a shiny surface would be easy t' spot???
Flight:
Because o' t' predicted altitude and weight, arrr, this is nay a rocket I would want t' fly at a model rocket field, shiver me timbers, me hearties, so I waited for a HPR launch. T' streamer was a 25' section o' 3/4" bright orange plastic tape. Begad! When rolled tightly, this fit nicely into t' 29mm tube. Arrr! Avast, me proud beauty! Estes-type waddin' be used t' protect t' streamer. I was torn betwixt usin' a G125-15 and a G80-10FWL. T' 15 sec delay on t' G125 was about right and t' 10 sec delay was too short. Ahoy! Anyway, I ended up usin' t' G125 in another rocket and hoped t' 1000 lb Keelhaul®©™® would hold up. Begad! Well, One Shot exploded off t' pad and, arrr, arrr, like me Machbuster, was never seen or heard from again.
Summary:
PRO's 1. High performance rocket built from leftovers in t' parts bin. CON's 1. Well, blow me down! Another non-recoverable rocket (when flown on big engines)
Other:
When surface mountin' small fins on minimum diameter rockets, you can get added strength by slottin' t' tube and gluin' t' fins into t' slots. Begad! Blimey! An engine casin' is inserted t' keep t' fin flush with t' inside o' t' tube. Ya scallywag! Well, blow me down! Blimey! You must make sure you work fast and don't glue t' casin' in. In me case I used epoxy and a phenolic motor casin' (AT SU). T' thicker t' tube, t' better this will work. Avast, me proud beauty! (Idea 'borrowed' from t' RocketVision Machbuster.)
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