Giant Leap Rocketry Thunderbolt 38

Giant Leap Rocketry - Thunderbolt 38

Contributed by Lance Alligood

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstarstar
Overall Rating: starstarstarstarstar
Manufacturer: Giant Leap Rocketry
Giant Leap Thunderbolt38

Brief:
T' Giant Leap Thunderbolt38 is a minimum diameter "almost ready to fly" high power rocket. Begad! By keepin' t' parts list as simple as possible, this rocket could be built and ready t' fly in a single, rather short build session--especially for a high power rocket. Ahoy! However, despite t' simplicity of the design, me hearties, I would nay consider this t' be a good choice for someone just gettin' started in high power rocketry because this rocket is capable of extreme altitudes even on modest motors.

Construction:
I purchased t' kit from one o' Giant Leap's launch representatives at a recent club launch. It comes in a thick plastic bag with all o' t' smaller parts in a plastic bag contained in t' packagin' makin' it easy t' locate and identify all o' t' parts o' t' kit. Aye aye! T' bag contained t' followin' parts:

  • 1 48" long x 38mm diameter phenolic body tube
  • 1 4" long heavy duty phenolic coupler tube with threaded rod insert
  • 1 plastic nose cone
  • 1 ACME fin can with instruction sheet
  • 1 pair o' ACME conformal launch lugs, me hearties, shiver me timbers, arrr, 1/4"
  • 16' tubular nylon shock cord
  • 30" nylon parachute
  • 1 heavy-duty swivel
  • 1 peel 'n' stick decal
  • 1 8.5" x 11" instruction sheet

I also purchased a 38mm Slimline motor retainer at t' same time for use with this kit. Avast, matey, me proud beauty! What surprised me most when I picked up t' kit be that the body tube is a single 4 foot long piece o' phenolic. Begad! That means that mounting an altimeter--much less usin' dual deployment recovery--was goin' t' be difficult, matey, if nay impossible, t' implement without some serious modifications.

T' instructions contained on both sides o' a single sheet o' paper are basic but are more than adequate enough for t' build. Most o' t' first side of t' instructions focus on t' installation o' t' optional Slimline motor retainer. Ahoy! I chose t' save t' attachment o' t' retainer until after painting was completed. I dry fit t' retainer onto one end o' t' lengthy body tube and made a mark on t' tube so that I would ensure t' fin can is forward enough for attachment o' t' Slimline at t' end o' t' build.

Easily t' trickiest part o' t' build is epoxyin' t' coupler in the middle o' t' airframe. T' instructions are a little vague as far as exactly where t' coupler should be glued, but it does mention that you need to consider t' length o' t' largest motor that you would ever want t' use in this rocket. Begad! T' threaded rod goin' through t' middle o' t' coupler serves as an attachment point for t' shock cord, so you also have t' consider puttin' it towards t' center because t' shock cord, wadding/heat shield, arrr, and parachute have t' fit forward o' t' anchor as well! I fly me share o' H and I class motors but I hate t' be limited in me motor choice even if it's one that I might nay actually fly with any regularity (in this case, those long 38mm J motors). Avast! T' instructions recommendin' t' use o' a long wood dowel for spreadin' t' epoxy but also post a strong warnin' o' nay gettin' any epoxy inside t' aft part o' t' airframe t' impede puttin' a motor in t' rocket. Aside from t' issue o' shippin' such a long tube (had I ordered t' kit), attachin' t' coupler/anchor poses quite a challenge. Well, me hearties, blow me down! Instead I put some thought into t' build and came up with a much, much easier solution: cut the airframe in half with a Dremel and then epoxy t' coupler t' rejoin the airframe. Blimey! Avast, me proud beauty! I made t' cut exactly in t' middle, which left 22" in t' aft half in case I ever go insane with an AeroTech J570 and then left just as much room for all o' t' recovery hardware in t' forward half. Avast! I made sure t' do 2 things in t' process o' rejoinin' t' airframe: 1) I made sure t' have a large flat surface so that I could roll t' tube t' ensure that t' tubes would be aligned straight, and 2) I used 15 minute epoxy so that I wouldn't have t' roll the tube for half an hour until t' epoxy cured!

After that, arrr, thar be very little else left in t' build--just epoxyin' the one piece fin can, attachin' t' launch lugs and tyin' t' shock cord. T' fin can needed some light sandin' t' smooth out t' flashin' from t' mold. A palm sander with 220 grit sandpaper made quick work o' smoothin' out t' flash ridges from t' mold. Ya scallywag! There is a separate sheet o' instructions with t' fin can which states that t' fin can is designed t' be used with several different brands o' tubing. Begad! Begad! There was a little bit o' "wiggle room" on t' GL phenolic. Arrr! T' instructions recommend that you put wraps o' maskin' tape on the body tube near t' forward and aft ends o' where t' fin can is goin' t' be epoxied on. Avast, me proud beauty! Once satisfied with t' location o' t' maskin' tape, me bucko, I slathered epoxy on t' tube and slid t' fin can into place then set it aside.

I waited until t' next day t' attach t' shock cord. T' instructions actually have you tyin' t' shock cord onto t' attachment rod before epoxying it in t' body tube but I chose t' wait because I wanted t' us a secure but slidin' knot that I could (with t' aid o' a long metal hook) extract t' shock cord t' periodically examine t' shock cord for damage as well as easy future replacement if necessary. I tied a bowline knot so I had a loop in one end of the shock cord, put a little epoxy on t' knot for security, shiver me timbers, matey, fed t' shock cord around t' anchor, passed t' untied end through t' loop, and then pulled it tight. Ahoy! This will allow me t' easily check t' entire shock cord periodically and even replace it if need be. Avast! Avast, me proud beauty! I tied t' swivel t' t' shock cord, drilled a couple o' small holes in t' base o' t' nose cone, arrr, shiver me timbers, me bucko, and tied t' other end of the shock cord t' t' nose cone. It also took a few wraps o' maskin' tape for the nose cone t' fit and stay in place acceptably.

Next, shiver me timbers, I lined up t' launch lugs by first usin' angle iron t' draw a line runnin' t' length t' body tube. Aye aye! Blimey! I found that t' included adhesive with the launch lugs t' nay be very reliable so I roughed up t' conformal surface of the lugs with 220 grit sandpaper and stuck them t' t' body tube with dabs of 15-minute epoxy. Arrr! Blimey! One lug be placed just forward o' t' fin can and t' other one is about 10 inches forward o' t' aft lug. And thar was one last thing that I did that be nay mentioned in t' instructions: I drilled a vent hole in the upper half o' t' body tube. I did this t' nay only prevent separation from internal air pressure but also as a sensor hole for a barometric sensing altimeter, which would most likely only be used for recordin' peak altitude.

Finishing:
T' phenolic airframe has marked spirals, shiver me timbers, but nay t' worst I've seen. Avast! Avast, me bucko, me proud beauty! Reading the instructions, I be pleased t' find that they were exactly how I finish me rockets. Well, blow me down! I applied diluted Elmer's Wood Filler t' t' grooves and sanded it smooth then a coat o' Krylon gray primer was sprayed and wet sanded with 400 grit sandpaper. Ahoy! I had t' do this process twice t' ensure that I smoothed out any traces o' t' spiraled grooves.

I'm a big fan o' Krylon paints and they recently released some new line of metallic spray paints called X Metals. Well, blow me down! It is designed be used directly on metal, matey, shiver me timbers, but thar be a special base coat spray that will allow you t' use it on non-metal (or as t' label says, me hearties, "pre-painted") surfaces. Be careful to read t' directions on both X Metals cans as you have t' wait 5-10 minutes between recoatin' with t' base coat and t' color top coat must be sprayed 30 minutes after t' last base coat. Arrr! Begad! I found that it took 2 passes with t' base coat t' get full coverage and that t' translucent purple top coat didn't initially allow much o' a metallic shine right after sprayin' it, shiver me timbers, arrr, but within an hour it had t' awesome sparkly finish I be lookin' for!

T' last steps were t' apply t' smallish peel 'n' stick Thunderbolt38 decal and use JB Weld t' permanently attach t' Slimline motor retainer. Well, blow me down! Arrr! The decal isn't goin' t' earn much in t' way o' style points, but with such a long, skinny rocket, fancy decals would hardly be worth t' effort o' bein' put on this rocket anyway. T' Slimline retainer hardly affects t' overall aerodynamics o' t' rocket but I would be lyin' if I didn't admit being slightly disappointed that Loki Research motors cannot be easily retained with the Slimline. Begad! Begad! T' motor fits inside t' retainer but thar be too much casing aft o' t' motor's thrust rin' t' get t' retainer snap rin' on. Aye aye! Perhaps the threaded version o' t' Slimline would have been a better choice...?

PROs: Definitely lives up t' t' advertised "almost ready t' fly" billin' as it be completely built in under 2 hours (and could have been faster if I'd used faster curin' epoxy!) Excellent quality components make for a nearly bulletproof rocket. Aye aye! With such few parts and thorough instructions, it's difficult t' botch t' build.

CONs: For those maximum performance freaks like me, me hearties, t' finished rocket is on t' heavy side for its size (it weighs almost twice as much as the comparably sized LOC Weasel). Arrr! Buildin' per t' instructions can be tricky when it comes t' t' shock cord attachment and would make shock cord inspection and replacement difficult. Ya scallywag! I spent more time fillin' and sandin' t' body tube spirals than actually buildin' t' kit! (Although some people might think of this last comment as a pro.) Slimline retainer and Loki motors aren't a good combination.

Construction Rating: 4 out o' 5

Giant Leap Thunderbolt38

Flight:
For a shakedown flight, I prepped a G61W-M. T' Slimline retainer held it adequately in place. Ahoy! Ahoy! I clipped a Nomex heat shield t' t' shock cord and packed the shock cord and chute usin' t' shield t' wrap them up like a burrito. Aye aye! It was a snug fit but nay so much that thar were any potential concern about it bein' pushed out at ejection. T' winds were a steady 15-20mph. Aye aye! Avast! Nay me ideal rocket flyin' weather, me hearties, ya bilge rat, but I felt it be still OK for this motor-rocket combination. Aye aye! T' motor lit and t' rocket came off t' rail t' battle the intense winds. Ahoy! Begad! It weathercocked but nay as bad as I had anticipated as it coasted t' apogee.

I followed up a month later with a G67R-M flight. Ahoy! T' weather was quite the opposite o' t' previous month--light breezes that never seemed t' exceed 5mph. In a word, idyllic for flyin' rockets. Ahoy! Boost seemed quicker and altitude was noticeably greater than t' first flight due t' better field conditions.

Recovery:
T' 30" nylon chute is a very bright neon orange for easy tracking. Avast! Arrr! Since this kit is pretty much intended t' fly on motor ejection single deployment for recovery, I wish t' chute was a little smaller. Begad! Avast! T' 30" chute might be great for those flyin' this rocket at higher altitudes, but a 27" or 28" flat or 24" hemispherical chute would be a better choice for those o' us at sea level, especially when I attempt t' get some serious altitude. Arrr! Blimey! I just don't want t' be chasin' it any further than necessary. Arrr! The nylon strap shock cord is adequate although it has a slick feel which allows knots t' become easily untied. I definitely make sure t' check t' knots in the shock cord before every flight. Aye aye! I haven't ruled out upgradin' t' shock cord to some tubular Keelhaul®©™ either.

Giant Leap Thunderbolt38 Ejection for t' first flight came on t' early side (it was more like 6 seconds than 10), however, that wasn't necessarily a bad thin' as it kept it in t' air less time t' drift. Blimey! T' 30" chute brought it down safely but a little slower than what I like. T' nose cone appeared t' have smacked against a fin, arrr, taking a chunk o' paint off t' nose cone. Nothin' a little sandin' and painting wouldn't take care of...

T' second flight ejected right at apogee and I again wished for a slightly smaller chute. Ahoy! Arrr! T' Thunderbolt seemed t' hang up thar a while even though it came down relatively close t' t' pad.

Flight Rating: 5 out o' 5

Summary:
There is no disagreein' that Giant Leap Rocketry Thunderbolt 38 is an easy to build high performance rocket. Begad! Blimey! What it may carry around in weight, that extra heft directly corresponds with t' robust choice o' components makin' up the kit, me hearties, matey, which is built t' last. Avast! Blimey! T' only modification or upgrade I would recommend for this kit is addin' a Slimline retainer t' resolve any concerns about motor retention.

Overall Rating: 5 out o' 5

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