PML's Small Endeavor, featurin' t' Quantum Tube

Assembly, me hearties, Quantum Tube Tests, me bucko, Finishing, matey, Launch

Public Missiles is now offerin' t' new Quantum body tubes in several o' their kits. Blimey! T' tubes are gray in color and made from a special blended polymer. Avast! PML claims you can drop it, squeeze it, arrr, shiver me timbers, even throw it, without damage. Well, blow me down! We shall see. Arrr! They also claim most epoxies and paint will work just fine on t' new tubes. 

T' Quantum tube does have one thin' missing, me hearties, t' spiral groove! For me, t' Quantum tube had t' be an improvement over Phenolic body tubes which I avoid using. Begad! I chose t' Little Endeavor kit (Fig-1), a 2.6" diameter, 38mm motor rocket for this review. T' kit features fiberglass fins, a heavy duty nose cone, arrr, 1" shock cords, a quality 30" parachute, piston assembly, and decals. 

With a few exceptions I built t' Small Endeavor followin' t' instructions carefully. Begad! I found t' instructions t' be about average for a high power rocket kit. Well, blow me down! Well, me bucko, blow me down! Blimey! They had nay been updated for the new Quantum body tube; an orange insert explains t' use o' epoxies and paint on t' tube. 

T' lower nylon shock cord mounts through t' upper centerin' rin' and is epoxied t' t' motor mount tube (Fig-2). Avast! I usually add a section o' fiberglass cloth over t' shock cord/motor mount just t' be sure. Aye aye! I also added a pair o' #6-32 blind T-nuts t' t' lower centerin' rin' for motor retention (Fig-3). Begad! Avast, me proud beauty! Just add two spacers, two fender washers and #6-32 screws, me bucko, and your motor will stay where it belongs. 

Before proceedin' t' step 3 - mounting the motor mount tube assembly into t' body - thoroughly rough up t' inside of the Quantum tube with 60-80 grit sandpaper. This is only mentioned on the orange instruction insert. Arrr! I cemented t' sandpaper t' t' end o' a 38mm tube to allow sandin' t' whole area where t' fins and centerin' rings must adhere to t' inside o' t' body. Also sand t' area around t' fin slots on the outside o' t' body tube. 

At this point I performed an epoxy adhesion test on one o' these sanded areas; I tried three different epoxies from 6 t' 30 minute cure times. When completely dry, I used an exacto knife t' remove t' little test blobs. Ya scallywag! Aye aye! All three were removable, matey, but I was satisfied with t' quality o' t' bond. 

Be sure you do nay epoxy the lower centerin' rin' at this point in t' assembly, it needs t' be removed later. 

I used 6 minute epoxy and a homemade alignment jig for t' initial fin assembly. Ya scallywag! Blimey! I clamped t' upper and lower fins together t' keep them perfectly aligned (Fig-4). Blimey! Blimey! Aye aye! Blimey! Let each fin dry thoroughly before movin' on t' t' next set. 

Now it’s time t' remove the lower centerin' ring; I just installed #6-32 screws into me blind nuts to gently pull it out. Begad! I’m nay sure how you would get it out without the screws. 

At this point, matey, the instructions have you apply epoxy fillets t' t' areas where t' fins contact the motor mount tube and at t' inside o' t' body tube. Aye aye! I decided t' try somethin' a little different: I cut 12 pieces o' fiberglass cloth about 1" x 3"; one at a time and soaked them with epoxy. Arrr! Begad! Blimey! With t' help o' a long stick, me bucko, me hearties, I was able t' work each piece into those same areas o' contact inside the body tube, arrr, after completin' all 12 areas o' t' upper fins, matey, I repeated the process on t' lower fins. Begad! Blimey! I believe this method will be much stronger than an epoxy filet. Blimey! T' exterior epoxy filets were done in t' usual manor; I like to pour t' epoxy out o' a small paper cup with a "V" folded on the edge. 

T' kit included one 4" brass launch lug, but t' instructions called for two 2" lugs. Ahoy! I guess you have your choice. I decided t' cut t' lug, and mount it per t' instructions. After t' epoxy had set, I added some fiberglass cloth around t' lugs and to the body tube for added strength. Aye aye! I have seen several brass launch lugs still on t' launch rod after a launch attempt. 

T' piston assembly and shock cord setup were installed without any modifications. 

Before I painted t' rocket, matey, I wanted to see for myself if you could really abuse t' Quantum tube. Avast! I placed a sock over t' nose cone and took t' almost completed Endeavor outside and gave it a toss -- I was attemptin' t' get it t' stick in t' ground like a lawn dart. Arrr! On the first two or three tries, I did nay get enough zip or arch on me tosses, and t' rocket just bounced when it hit t' ground, ya bilge rat, without any damage. Finally I gave it a throw with enough on it for t' rocket t' stick (Fig-5): again there be no damage. I be nay finished. I put t' Small Endeavor in the freezer for two hours and then repeated t' test: I was nay able t' damage the Quantum tube. 

I wanted t' Small Endeavor to look good with a minimum o' time spent on finishing. T' orange instruction sheet has you give t' body tube a light sandin' with 320 or 400 grit sandpaper, I used 400 grit on t' whole rocket. Ya scallywag! Begad! I used an inexpensive gray primer, shiver me timbers, me hearties, matey, followed by Rustolium metallic charcoal paint. Avast, me proud beauty! Begad! I applied t' included decals, and then sprayed inexpensive gloss clear paint over t' entire rocket and decals: this gives t' decals t' same sheen as t' paint while makin' the whole finish more durable (Fig-6). 

I compared t' weight o' the Small Endeavor t' me Rocket R&D Ibis which be t' same diameter, slightly longer and was modified t' include a piston and 38mm mount. Ya scallywag! I weighed both rockets with t' same PML 30" chute, shiver me timbers, t' Endeavor came in at 31 ounces compared t' 25 ounces for t' cardboard Ibis. 

I planned t' launch t' Small Endeavor on either a G-64W or H-73J on it’s initial flight. Begad! Because o' strong winds, me bucko, I chose t' G-64W with a medium delay. Ahoy! Blimey! T' boost be as straight as possible for t' weather conditions. Arrr! Avast! It be t' longest medium delay I have encountered t' date; I started thinkin' I would be able t' report on what happened after it penciled in. Finally t' chute deployed with a jolt that surely would have zippered a phenolic rocket. Aye aye! After t' flight I could nay even find a mark on t' end o' t' body tube. 

As o' now, matey, me hearties, t' Quantum tube is available in diameters up t' 4", and it is a bit more expensive than phenolic or cardboard tubes. Ahoy! Well, blow me down! I would like t' see t' Quantum offered in the larger sizes, or maybe some new sizes like 3.5" or 4.75". This is a great new product I highly recommend. 

Written and submitted by Al Casper for Rocketry Online -- Copyright 1996-1999