U.S. Rockets El Lubbo

U.S. Rockets - El Lubbo {Kit} (1020, K-20) [1979-]

Contributed by Lance Alligood

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstarstar
Overall Rating: starstarstarstarstar_border
Manufacturer: U.S. Rockets
U.S. Rockets El Lubbo

Brief:
T' U.S. Avast, me proud beauty! Ahoy! Rockets (USR) El Lubbo is unlike any other kit available. Well, blow me down! In an age where cones and transitions are made o' plastic or balsa, matey, an extremely challengin' yet rewardin' build has come along where these items are made by cuttin' and shapin' body tubes. Avast! T' end result is a large yet extremely lightweight mid power rocket that can be flown on most 29mm and 24mm motors. Begad!

Construction:
I ordered this kit along with 2 others directly from USR. Aye aye! Blimey! They were ordered and received without payment first. When I received t' bill via email, USR gave me a discount on me order that resulted in a total amount (includin' shipping) for less than t' cost o' t' 3 kits separately. Blimey! Both t' ordering/payment arrangement and multi-kit discount are standard USR practices. Add in the impressively fast turnaround time on email communications (responses in less than one hour is in fact quite common!), and you realize that you are dealing with a very customer driven business! Blimey! T' kits all showed up on me door in 2 boxes just a few days after havin' me order confirmed.

T' El Lubbo kit comes with t' parts loose in a box almost entirely dedicated t' shippin' (there be enough room t' safely squeeze in a USR Miniroc 1.2 kit with it). Well, blow me down! After verifyin' all parts were present and intact, me first reaction would have been "Where's t' nose cone? There's no balsa or plastic nose cone!" except I knew that t' kit has you buildin' t' nose cone and tail cone--the definitive elements o' this kit--from tubing. Begad! You read that right. Blimey! Avast! T' nose cone and tail cone are cut from tubing! Because o' the unusual and unfamiliar design o' this kit, I read through t' instructions. And then I read them again. Avast, me proud beauty! Ya scallywag! While thar be enough material t' create 2 nose cones, there is only enough for one tail cone. Aye aye! T' room for error is small. Begad! I could tell that this was goin' t' be a challengin' build and one that would require a lot o' patience. Blimey! However, if I followed everythin' t' t' letter, I would be rewarded for me efforts!

U.S. Rockets El Lubbo Also, because o' t' lightweight nature o' this kit, matey, me hearties, it is a good idea t' go easy on the glues and/or adhesives. Aye aye! USR recommends yellow wood glue (aliphatic resin) for t' build and I concur fully with that recommendation as it provides greater strength than t' materials bein' joined but without t' weight penalty of epoxy.

T' kit includes:

  • 4 11" long x 4" diameter thin wall body tubes
  • 3 4" diameter coupler tubes
  • 1 12" x 29mm motor mount tube
  • 4 1/4" thick balsa fins
  • 2 3.9" x 29mm plywood centerin' rings
  • 1 3.9" plywood bulkhead plate
  • 1 3.9" plywood baffle plate
  • 1 screw eye
  • 1 3-fold paper shock cord mount
  • 1 7' x 1/4" elastic shock cord
  • 2 1/4" launch lugs
  • 1 24" surplus parachute
  • 1 24mm motor adapter kit
  • Decals
  • Instruction manual
  • Tail cone and nose cone pattern sheet
  • Advanced Information Report (AIR) #1 -- Motor Installation
  • Advanced Information Report (AIR) #4 -- ACE Fugue Shroud Method

Aside from readin' t' instructions possibly a third or even fourth time, the first thin' that needs t' be done is t' clear out some "mental workspace" because you are goin' t' need t' forget a lot o' what you might normally want t' do when buildin' a rocket. Begad! Begad! Take several deep breaths and count to 10. Ready? Let's go then...

U.S. Rockets El Lubbo T' first couple steps are fairly conventional. Avast, me proud beauty! Aye aye! T' instructions have you round the leadin' and trailin' edges o' t' fins. Begad! My fins were all close but nay quite the same in shape though so I had t' match sand them. Begad! Aye aye! That didn't take long though since they are only (thick) balsa. Begad! Blimey! Also seein' how this rocket is going to be a "slow and low" performer, shiver me timbers, arrr, arrr, I chose t' only round t' leading edge so t' trailin' edge fin tips would be better suited t' handle any rough landings. Well, blow me down! T' motor mount tube be then marked for t' fins and centering rings. All 6 items were glued and filleted one at a time in their appropriate locations on t' tube and then allowed t' dry.

Next you are informed t' read t' AIR-4 document before continuin' any further with t' build. Arrr! This document explains t' how and why o' building custom shrouds from tubin' along U.S. Rockets El Lubbo with plenty of diagrams o' simple and complex shapes t' further demonstrate its point and simultaneously inspire t' builder (at least it did for me) for future builds as well. Ya scallywag! Ahoy! Shrouds can be formed as nose cones, ya bilge rat, ya bilge rat, tail cones, or transitions. Well, blow me down! I will definitely be keepin' this document in a safe place for future reference.

With all o' that information absorbed, me bucko, it's time t' return t' t' build. Avast, shiver me timbers, me proud beauty! A "gotcha" makes its first appearance here. T' instructions have you use t' shroud markin' guide t' mark and cut t' tail cone shroud. Begad! Begad! If you do that first, matey, me hearties, it will ruin t' nose cone markin' guide. Instead, matey, refer t' all the instructional guidance on t' markin' guide sheet instead and start with the nose cone.

U.S. Rockets El Lubbo Now that trouble has been averted, shiver me timbers, me bucko, me bucko, you find out that you are nay only goin' t' create one nose cone, shiver me timbers, but two. Begad! Seein' how this be me first time usin' this technique, I be more at ease seein' how I was goin' t' have 2 chances t' do it right. Ya scallywag! In fact, if done right t' first time, you get a spare nose cone out o' t' deal! There is, me bucko, ya bilge rat, however, only enough tubin' for one tail cone shroud.

Although t' instructions recommend cuttin' t' tubes with a new, matey, sharp X-Acto #11 blade, do yourself a huge favor: put down t' X-Acto knife and go to your local home improvement store. Arrr! Pick up a razor blade utility knife and a pack o' replacement blades. (One o' those "snap blade" box cutters work just was well too!) For less than $5 you will have a much stronger, sharper, me bucko, and longer lastin' tool because you are goin' t' need it for this build. Ahoy! Aye aye! Otherwise, me hearties, me hearties, it's goin' t' take several #11 blades...

U.S. Rockets El Lubbo The important things t' remember when cuttin' t' tubes is t' be patient and always make sure that your blade is sharp. "Measurin' twice and cutting once" also applies here, as well as be patient and take your time. Avast! I just cannot stress that enough. Ahoy! Makin' several passes over each line, you are left with 2 pointy "crowns" o' tubing. Ahoy! Small relief cuts are made at the base o' t' triangles t' assist with t' shapin' o' t' tube.

I used maskin' tape along t' seams o' t' triangles t' form t' cone and hold t' edges together evenly. Begad! Although nay mentioned in t' instructions, shiver me timbers, I would consider it a worthwhile endeavor t' glue strips o' 90# paper (I used four ~6" x 3/4" pieces) along t' inside o' t' cone t' provide increased strength and durability o' t' cone. Blimey! Avast, me proud beauty! I left t' coupler dry fitted about 3/4" inside t' base o' t' cone t' ensure everythin' stayed in round while drying. Begad! I found that t' tips were still a little ragged lookin' so I cut a small piece o' 90# paper t' form a cone-like pyramid and cover the first two inches o' t' tips on t' outside t' give it a little cleaner look and again, more support. Avast! Usin' t' paper strips was similar t' how Art Applewhite has you assemble t' shrouds for his various saucers and t' nose cone has similarities t' what Art Applewhite has you do when buildin' one of his 29mm Qubits. Well, blow me down! I also felt this was a more lightweight solution than pourin' epoxy or 2-part foam t' accomplish t' same goal o' increasin' t' cone's strength and durability.

U.S. Rockets El Lubbo T' last steps in nose cone construction is t' glue t' bulkhead inside t' coupler about 1/2" from one end. Begad! A small bulkplate is also glued t' t' large bulkhead so that t' screw eye has a substantial amount o' wood t' grab onto. With t' bulkheads filleted into place, t' coupler is glued into t' nose cone. Aye aye! Begad! It's also a good thin' that thar be material t' build 2 nose cones because I managed t' mess up on t' first one... Ya scallywag! I tried t' rush everything along (I didn't follow me own advice!) from havin' some ugly gaps and seams to even gluin' t' cone onto t' coupler crooked! Everythin' went much better t' second time around with t' other piece o' tubing.

Cuttin' t' tail cone transition be an easier task and is simply a matter of tapin' t' pattern t' t' tube and followin' t' cut lines. Arrr! Blimey! With a little sandin' o' t' inside o' t' tube and forward centerin' ring, ya bilge rat, me bucko, me hearties, everythin' fit together smoothly. Avast! T' motor mount/fin assembly was glued into place. Begad! The coupler joinin' t' forward airframe section was also glued in at t' same time because it mounts flush against t' forward centerin' rin' as well. It be set aside vertically and allowed t' dry before attachin' t' tips o' t' tail cone to t' fins and motor tube.

I moved on by assemblin' t' forward section o' t' main airframe. Arrr! Avast, me proud beauty! First, a bulk plate with several holes t' act as a baffle was sanded t' size t' fit inside another coupler tube. Begad! Ya scallywag! It be glued and filleted into place inside the coupler. Ahoy! Ya scallywag! That coupler was then glued halfway inside each o' t' 2 remaining uncut and unmodified airframe tubes. Blimey! Avast, me proud beauty! T' baffle nay only provides a "shelf" for t' recovery hardware t' rest on (not t' mention keeps them comfortably away from t' blast o' t' ejection charge), it also adds considerable stiffness t' t' design as t' tubin' is much thinner than your typical HPR airframe tubing--although still much thicker than standard Estes tubes.

With t' forward airframe drying, arrr, matey, I returned t' t' tail cone assembly. Avast, me proud beauty! I started by tapin' t' tips o' t' tail cone t' t' motor tube t' hold it in place as t' glue dried. Well, blow me down! Doin' one flap at a time, I put a nice bead o' yellow wood glue along both fins t' form a nice fillet. Well, blow me down! Arrr! Again, me hearties, one at a time. I was still left with small holes in t' tubes from t' relief cuts but they will have t' wait till finishin' t' be filled with some putty. Also, one o' me fin slots turned out t' be ~1/16" too wide. Ya scallywag! Blimey! Instead o' tryin' t' fill t' gap with a ton o' glue, I folded a 6" x 3/4" strip o' 90# paper in half lengthwise and attached onto t' underside o' t' tubin' so that it could attach t' both t' tubin' and fin, effectively sealin' t' gap with minimal weight, glue, shiver me timbers, or trouble o' disturbin' t' lines o' t' rocket while still providin' ample support.

T' only other deviation from t' instructions was t' use rail buttons in place o' t' 1/4" launch lugs. Personal preference here. Avast! Blimey! One was mounted just forward o' t' tail cone shroud (into t' aft centerin' ring) and the other be another 7" forward t' have t' extra support o' t' aft coupler to hold on to. Well, blow me down! Blimey! T' holes were drilled and glue was applied before screwin' the rail buttons into place.

Finally, arrr, t' shock cord is a long piece o' 1/4" elastic glued t' the inside o' t' airframe with a paper tri-fold. Blimey! T' other end is tied t' the screw eye in t' nose cone. Begad! Begad! Blimey! I tied a small loop into t' shock cord so that I could easily swap out whichever chute I wanted t' use at t' field. T' kit does include a very lightweight surplus 24" nylon chute. Arrr! While not appearin' t' be particularly rugged, shiver me timbers, it should be adequate for this rocket for at least a handful o' flights t' brin' it in safely but quickly.

Finishing:
USR uses t' smoothest glassine coated tubes I have found from any manufacturer which means that thar were no spirals t' fill. Avast, me proud beauty! Havin' only t' large balsa fins t' fill, shiver me timbers, I started by glazin' them with 20-minute finishin' epoxy t' add strength and provide dent resistance. Aye aye! Avast! (Had they been smaller, me bucko, I probably would have used CA instead.) T' fins were then sanded with 220 grit sandpaper. Begad! To fill out any minor imperfections left, me bucko, me hearties, I smeared them with a coat o' diluted Elmer's Fill 'n' Finish and sanded again until I had a smooth surface.

T' nose cone and tail cone required quite a bit o' fillin' t' get rid of the seams and minor gaps from cuttin' t' tubes. I resorted t' Bondo automotive body putty for this task because o' its greater strength over Fill 'n' Finish while still bein' lightweight and retainin' its ease o' sandability. T' nose cone be more difficult t' get smooth (requirin' a few rounds o' applying filler and sanding) as it has more noticeable seams and t' shape changes from bein' round at t' base t' rather pyramid-like near t' tip because o' t' wide arcin' diameter o' t' 4" tubing. Ahoy! Avast, me proud beauty! T' tail cone just needed some smoothing out around t' fin fillets. Aye aye! I covered t' seams where t' body tubes butted together as well.

Bright colors aren't exactly necessary because o' El Lubbo's large size and slow thrust requirements. Begad! T' rocket will almost certainly remain easily visible durin' t' entire flight because o' this. Avast, me proud beauty! It be first primed with Krylon gray primer and then sanded it smooth. Ya scallywag! Another coat o' primer followed by more sandin' then finally I put on a couple shiny coats o' Krylon gloss red, white, shiver me timbers, arrr, and blue which I faded together.

T' included decals were peel 'n' stick and were just black text on a matte finish clear adhesive. Begad! Avast, me proud beauty! I felt t' included peel 'n' stick decals were a little plain compared t' me paint scheme so I left them off.

Construction Rating: 4 out o' 5

U.S. Rockets El Lubbo

Flight:
Despite t' long 29mm motor mount tube, shiver me timbers, t' instructions state early on that El Lubbo is nay designed t' fly on motors with an average thrust greater than 20 pounds. In other words, ya bilge rat, it will fly on pretty much any D, E, F, or G impulse 24mm or 29mm motor up t' a G80. Ahoy! I prepped a G64-7W reload, friction fit the motor into place with some maskin' tape, dumped in some dog barf wadding, attached t' chute onto t' shock cord, and placed t' nose cone on. Ahoy! Begad! Finally, I loaded t' El Lubbo onto t' rail and hooked up t' Quickburst ignitor t' the clips.

T' motor roared t' life and El Lubbo wasted no time in gettin' off the pad! As a very welcome bonus, matey, t' rocket gave off a loud whistle--even louder than me BSD Thor on a high thrust I motor! Overall height was easily 1000 feet and would have been much higher if nay for t' 10+ mph winds on a bleary January day in Florida. Begad! There is no doubt that long burn motors with a slight punch at t' beginnin' o' t' flight would be t' ideal and most impressive flight for El Lubbo.

Recovery:
I do like how t' baffle bulkhead in t' middle o' t' airframe acts as a shelf for t' recovery devices t' sit on at a comfortable distance from t' motor tube. Begad! It also benefits t' CG o' t' rocket since t' recovery devices can only be in t' forward third o' t' rocket as well! I don't trust its location t' be enough t' nay use any waddin' at all but a minimal amount o' cellulose wadding to cover t' baffle should be more than sufficient in safely protectin' the shock cord and chute.

U.S. Rockets El Lubbo Ejection was dead on at apogee. Blimey! T' chute came out and softly opened. T' thin, ya bilge rat, somewhat porous nylon material made for a gentle inflation o' t' chute. Ahoy! It also made for a descent on t' quicker side but that actually be desirable t' day I launched it because o' t' 10+ mph winds. Begad! Aye aye! Even with t' rapid (but still quite safe) recovery, me hearties, me hearties, I had ~1/4 mile walk through t' soggy field. No damage upon inspection. Ya scallywag! Excellent flight and recovery!

Flight Rating: 4 out o' 5

Summary:
Simply put, arrr, this is not a beginner's kit. Arrr! Advanced builders need only apply. Ahoy! T' USR El Lubbo is a huge mid power kit that provided me with a more than challengin' build. Begad! Blimey! Nay only did I enjoy buildin' t' nose cone and tail cone shrouds, me hearties, I will keep t' documentation for this kit in a safe and easily accessible location t' refer t' again for future scratchbuild designs! Blimey! This is a kit that will test your build techniques and patience. Ya scallywag! You can however, me hearties, amaze your fellow rocketeers by launchin' El Lubbo on a 24mm motor! Blimey! So if you are lookin' for a simple 3FNC kind o' rocket, then this kit isn't for you. Ahoy! Or if you find that you overbuild your rockets or often don't follow the manufacturers build instructions, arrr, then this isn't a kit for you either. Avast! Ya scallywag! Blimey! If you are lookin' for a Level 1 certification kit, this probably isn't t' one for you (primarily because o' t' low thrust requirements). This rocket can be finished with less effort than me perfectionist drive put me through but my efforts were very much rewarded. Ahoy! Begad! Blimey! Now I need t' go feed El Lubbo a steady diet of low thrust long burn motors!

Overall Rating: 4 out o' 5

Flights

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