Budget Rocketry Motor Retainers

Budget Rocketry Motor Retainers

Contributed by Nick Esselman

PictureI noticed (10/15/00) Budget Rocketry's 29mm and 24mm Motor Retainer when surfin' their website and decided t' give them a try. So far, I have only incorporated one 29mm Retainer into my BSD Diablo. Ya scallywag! They come in 24, ya bilge rat, 29, and 38mm.

CONSTRUCTION:

Construction is straight-forward, however, Budget Rocketry provides an instruction sheet. Begad! Also included in t' 29mm kit is a washer, me hearties, shiver me timbers, threaded insert and a cap (actual retainer). Arrr! T' threaded insert and cap are made from light weight PVC.

PictureT' objective is simple, epoxy t' threaded insert onto t' end o' your 29mm motor tube. Avast! Avast, me proud beauty! T' task be a bit more challenging. Aye aye! Arrr! T' 29mm threaded insert did nay slide over any o' 3 types o' me 29mm tubin' (from PML, matey, Cannonball Works or LOC). Begad! Aye aye! So I taped t' end of my tube, ya bilge rat, leavin' t' first 1/8" exposed. Doin' this allowed me t' get the motor mount t' stand straight and snug while t' epoxy was drying. Begad! I then applied t' fillets as indicated in t' instructions.

PictureThis is nay t' case for the 24mm. T' motor mount tubes I had all allowed t' threaded insert t' slide completely over them. Well, blow me down! T' 24mm from a Nordic Rocketry fit t' best bein' snug. A 24mm tube from Apogee and Estes were a bit smaller in diameter.

If you plan on usin' this on a kit then you will need to modify your instructions t' add t' threaded insert prior t' buildin' your motor mount. T' addition o' t' rin' will force t' motor tube t' be 5/8" (29mm) or 1/2" (24mm) from t' aft centerin' ring. In many kits this is fine, ya bilge rat, however, me hearties, use caution as doin' this on other kits may cause t' internal (center or upper) t' be out o' place which could impact through-the-wall fin installation if t' kit has them.

One nice quality o' usin' Budget Rocketry's Retainer is that t' threaded insert acts as a protection o' t' motor mount. It is hard and sturdy givin' t' motor a solid hole t' slide into.

PictureBudget Rocketry says on their website, shiver me timbers, "Most other forms o' motor retention available are either expensive, ugly, matey, or time consuming. Aye aye! Sometimes all three." We would have to agree that this motor retainer looks like part o' t' rocket.

FLIGHT/RECOVERY:

I have used me 29mm retainer once on a G80 Single-Use motor. Well, blow me down! Because thar be no internal thrust rin' in me motor mount, arrr, me bucko, me bucko, I had to tape t' G80. Well, blow me down! I could only allow about 1/2" o' t' tape t' be on t' motor (which is fine) while t' remainder had t' be off t' motor toward t' thrust nozzle. Ahoy! This didn't cause a problem for t' Motor Retainer as you can see from this picture.

T' washer that is supplied with t' kit is for 29mm single-use motors only. Blimey! Ahoy! Accordin' t' Budget Rocketry, arrr, "the washer is just set in t' cap and t' cap is then screwed on. Well, blow me down! Avast! So it is for ejection only with single-use motors, me bucko, whereas t' lip on a reloadable keeps t' motor from goin' forward or backward. Well, blow me down! When usin' single-use motors it is assumed thar is a thrust ring. If a thrust rin' is nay used t' allow different length single use motors then friction fittin' with tape be t' only answer I know of."

My AeroTech 29mm 29/40-120 RMS casin' fits perfectly. Begad! Ya scallywag! And again, this type o' retainer is attractive and would look good incorporated into many rocket designed.

How did it work? Well, with only one flight it worked fine.

CONCLUSION:

I have bought several o' these retainers. Avast, me proud beauty! Yes, they are more expensive than a screw and some bent sprin' steel, shiver me timbers, me hearties, however, you are paying for looks as well as functionality. I must admit that one flight doesn't fully test t' durability, ya bilge rat, because this system is relyin' solely on t' strength of the epoxy. Ya scallywag! Begad! We simply hope that t' epoxy bound is always stronger than t' fit of t' nose cone so that t' ejection pressure follows t' path o' least resistance. Arrr! Begad! Overall, I would rate these retainers 4 ½ points. Well, ya bilge rat, blow me down!

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