U.S. Rockets Weightlofter

U.S. Rockets - Weightlofter {Kit} (1019, K-19) [1979-]

Contributed by Lance Alligood

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

Brief:
T' U.S. Rockets (USR) Weightlofter is a 7-motor mid power cluster rocket with six 24mm outboard tubes and one central 29mm motor tube. Ya scallywag! This also is a great kit for someone that is lookin' for a challenging, labor intensive mid power rocket build. A 24mm motor adapter is included so that it can be flown on a smaller central motor as well.

Construction:
I ordered this kit along with 2 others directly from USR. Avast! They were ordered and received without payment first. Ya scallywag! 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. Ahoy! Both t' ordering/payment arrangement and multi-kit discount are standard USR practices. Avast! Well, shiver me timbers, blow me down! Add in the impressively fast turnaround time on email communications (responses in less than one hour is in fact quite common!), me hearties, and you realize that you are dealing with a very customer driven business! T' kits all showed up on me door in 2 boxes just a few days after havin' me order confirmed.

T' Weightlofter kit comes inside o' a plastic bag with hang tag typical of most rocket kits you would find in a hobby store. Avast, me proud beauty! Initially I thought that there had t' be more than just a couple o' tubes and a nose cone before opening the bag and I sure wasn't disappointed when I opened it--an amazin' assortment of parts came out o' t' large body tube! After verifyin' all parts were present and intact (which took a while), I read through t' instructions. The Weightlofter is rated a skill level 3 and I wanted t' scout out any potential "gotchas".

T' kit includes:

  • 1 2:1 ogive balsa nose cone
  • 1 18" x 2.25" body tube
  • U.S. Rockets Weightlofter
  • 1 9" x 2.25" body tube
  • 1 6" x 29mm MMT tube
  • 6 3" x 24mm MMT tubes
  • 1 coupler tube
  • 2 1/8" thick plywood centerin' rings
  • 1 2.17" plywood coupler bulkhead plate
  • 1 1.21" x 3/32" plywood bulkhead plate
  • 1 screw eye
  • 1 3-fold paper shock cord mount
  • 1 7' x 1/4" elastic shock cord
  • 3 1/8" thick plywood fins
  • 1 1/4" launch lug
  • 1 16" mylar parasheet (parachute)
  • 1 24mm motor adapter kit
  • Decals
  • Instruction manual
  • Advanced Information Report (AIR) #3 -- Motor Installation, me hearties, Clustering, and Staging

After lookin' over t' instructions, me bucko, matey, I saw that this be goin' t' be a much different build than I had anticipated at t' time o' orderin' t' kit. First off, me bucko, ya bilge rat, thar be no tube slottin' or cuttin' t' be done. Arrr! T' motor mount will take longer than a 3FNC t' build but mostly it's time spent waitin' for glue t' dry. Speakin' o' glue, USR recommends that yellow wood glue (aliphatic resin) be used for assemblin' t' Weightlofter and I completely agree with that recommendation.

U.S. Rockets Weightlofter I started by lightly sandin' all motor mount tubes and t' short airframe tube (all USR tubes are glassine coated and practically seamless) so that t' wood glue would have somethin' t' bite into. Avast! I also smartly sanded t' slightly rough edges o' t' bulkheads and centerin' rings so that all parts would fit smoothly together.

T' short airframe tube is first marked with assistance from t' alignment guide in t' instructions t' aid in t' placement o' t' fins and outboard motor tubes. Well, blow me down! Ya scallywag! Then I started t' assembly by gluin' and filletin' t' centering rings onto t' 29mm tube. Ya scallywag! Both rings are near one end o' t' tube so that when inserted into t' small airframe tube with t' aft centerin' flush with end of the larger tube, about half o' t' motor tube is hangin' out. Blimey! While t' central motor mount is drying, t' smaller 24mm motor tubes are gathered up and glued together in matchin' pairs. Avast, me proud beauty! After they have dried, each pair is attached t' the 29mm tube so that they are centered on each o' t' 3 lines o' t' main airframe tube. Well, blow me down! Aye aye! This leaves about half o' t' forward end o' these tubes exposed outside the diameter o' t' 2.25" main airframe tubing. Ahoy! At this point I allowed everythin' t' dry overnight before continuin' t' build.

I was really impressed with t' 1/8" plywood fins in this kit. They had t' telltale burned edges o' bein' laser cut, were a precise matched set, and o' high quality material that assured me that they could hold up t' the thrust o' 7 motors while only bein' surface/wedge mounted. Well, blow me down! Avast, me hearties, me proud beauty! T' instructions recommend airfoilin' or at least roundin' t' leadin' and trailin' edges. Ya scallywag! I chose t' only round t' leadin' edge. Begad! Details, however, were light regarding attachment o' t' fins t' t' body. T' root edge required a fair amount of work as all 3 fins need t' use wedge attachment t' fit in t' valley between each pair o' 24mm tubes but remain flat t' attach along t' larger 2.25" airframe above it. Begad! Ya scallywag! That meant sandin' a V shape into t' bottom 3" o' the root edge. Blimey! My Dremel with sandin' drum attachment made quick work o' this task. It only took a couple minutes or so per fin because I didn't need t' be as focused on looks as much as a good fit, which meant I left a slightly rugged edge for t' glue t' adhere to. Aye aye! Begad! It proved t' be quite beneficial t' do this! (Gotcha #1: I should note that one fin required some additional sandin' along the root edge because I had used a little too much glue t' attach t' 24mm tubes together earlier on.) Completin' this same task by hand for all 3 fins would have taken considerably longer and been significantly less enjoyable. Ya scallywag! The fins were attached one at a time with yellow wood glue, aligned, me bucko, matey, and held in place with maskin' tape until dry before attachin' t' next fin. Aye aye! Ya scallywag! Fillets were applied in t' same patient manner, matey, which indeed took a while as thar are quite a few!

U.S. Rockets Weightlofter While I prefer rail buttons on me mid and high power rockets, ya bilge rat, ya bilge rat, shiver me timbers, t' Weightlofter would require some serious standoffs for t' rail buttons t' have enough clearance over t' outboard motor tubes. Begad! Well, blow me down! That meant keepin' it simple by goin' with the included launch lug. T' 1/4" launch lug is cut in half at an angle (to help minimize drag). One half is glued even with t' aft end and nested between a gap in t' outboard tubes and t' other half is mounted at t' forward end of the short main airframe tube. Begad! Arrr! Fillets were applied t' them as well.

T' elastic shock cord is attached inside t' short main airframe tube with the tried-and-true paper 3-fold method. Ya scallywag! T' other end is tied t' t' screw eye and t' streamer is attached in t' middle (although I chose t' clip it on with a snap swivel from me range box).

T' payload bay and coupler were nothin' out o' t' ordinary. Well, arrr, blow me down! There are 2 bulkheads, one that fits nicely inside t' coupler tube and a smaller one (~1.25" diameter). Avast, me proud beauty! These are glued together t' create a single bulkhead that is thicker in t' middle than t' edges, me bucko, me hearties, ya bilge rat, allowin' for a minimal but worthy weight savings. Arrr! T' screw eye is twisted into t' bulkhead and t' subassembly is glued and filleted into t' coupler tube. Avast! Avast! Once dry, t' coupler tube is glued halfway into one end o' t' 18" payload tube. USR recommends t' add noseweight for G and larger motors t' ensure stability and provide additional momentum durin' high thrust flights. Begad! For this purpose, I chose t' friction fit the nose cone. When t' time comes, shiver me timbers, ya bilge rat, weight will probably be a simple, flexible system that will allow flat washers t' be screwed into t' base o' t' nose cone. And although nay mentioned in t' instructions, matey, arrr, 1/16" vent hole were drilled into t' payload and main tube t' prevent any premature separations durin' flight.

U.S. Rockets Weightlofter The last step in t' build is t' assemble t' 24mm motor adapter, me bucko, matey, arrr, which consists of 2 tubes that are glued inside each other. Maskin' tape is needed t' provide a snug fit and form a thrust rin' before usin' it.

Overall, this turned out t' be an easier yet more labor intensive build than what I had originally thought it be goin' t' be when I looked through the instructions. Because o' t' complicated motor mount assembly and fin attachment, ya bilge rat, t' Weightlofter is worthy o' t' manufacturer's ratin' as a skill level 3 kit in me book. Avast! Gotcha #2: T' USR Weightlofter is designed for clustered mid power flights, matey, me bucko, nay necessarily large single motor flights. Blimey! Aye aye! With the rocket fully assembled per t' instructions, thar be only 4.5" available inside t' airframe from t' forward end o' t' motor mount tube to the bottom o' t' payload tube coupler for wadding, shock cord, and chute. That's enough room for those parts but it's still a relatively small volume of space. I recognized this situation was goin' t' occur back when I read through the instructions (before even beginnin' t' build and again when doin' a dry fit o' t' parts), but I was content with buildin' this kit stock. A simple resolution for anyone desirin' more room could easily build this kit with 2.25" tubin' flip-flopped--the 18" tube attached t' t' motor mount and t' have a shorter 9" payload section.

Finishing:
T' balsa nose cone be prepped for paint by glazin' it with 20-minute finishin' epoxy, sandin' t' rough spots with 220 grit sandpaper, me bucko, applyin' a thin coat o' diluted Elmer's Fill 'n' Finish, me bucko, shiver me timbers, and followin' that with more sandin' t' give it a hard, me bucko, smooth shell. Avast, me proud beauty! Ahoy! T' fins had a coat o' diluted Elmer's Fill 'n' Finish smeared on and sanded as well t' remove any traces o' wood grain. Avast, me proud beauty! In an effort t' minimize a buildup o' paint inside t' outboard motor tubes (and therefore make it difficult t' insert/remove motors in t' future), I balled up some newspaper and stuffed it inside all 6 outboard motor tubes. Ahoy! My paint stand has a used 29mm SU motor t' support t' rocket in t' central MMT, so no worries about gettin' any paint overspray there. Ya scallywag! T' entire rocket was then given a coat o' Krylon gray primer and sanded with 320 grit. Avast, me proud beauty! I found some low spots that needed a little extra FnF and sanded everythin' smooth followed by a coat o' Krylon white primer. Begad! Blimey! A third gotcha presented itself during primin' (and paintin' later on) because o' t' gap betwixt t' 24mm tubes. Ya scallywag! Care needs t' be taken t' get paint in thar but nay so much at one time t' cause a run. Well, blow me down! One more pass with 400 grit sandpaper t' make sure everythin' was smooth and it be ready for final paint.

T' suggested paint scheme is florescent colors in a pattern t' detect body roll durin' flight, ya bilge rat, otherwise it is left up t' t' builder t' come up with anythin' more decorative than that. Well, blow me down! I like how t' Weightlofter is similar in size and stature t' me USR Banshee so I thought I would use a similar paint scheme on t' Weightlofter. Avast! I would have used t' same colors but I did not have enough orange. I did have plenty o' yellow and blue though. Avast, me proud beauty! T' yellow was sprayed first and allowed t' dry before maskin' t' stripes with clear tape and layin' down t' blue. Aye aye! After waitin' a good 24 hours, t' rocket was rubbed down with 3M Rubbin' Compound and an old T-shirt t' give it a nice shine and help smooth out any minor flaws or ridges in t' paint.

Construction Rating: 4 out o' 5

U.S. Rockets Weightlofter

Flight:
T' Weightlofter can be flown on 1, 3, 4, 5, arrr, or 7 motors. Aye aye! Blimey! Any empty outboard motor tubes act as stabilizers when empty. Ya scallywag! Ya scallywag! Regardless o' t' number used, there must be one in t' central mount for t' recovery device t' be ejected. All outboard motors should be plugged or zero-second delay booster motors if BP or have t' ejection charge removed if AP t' prevent any unwanted damage from ejection charges. Avast! As noted in t' instructions, nose weight is needed for most clustered flights. Avast! No suggestions are give on how t' add noseweight but fender washers screwed into t' base o' t' nose cone have been an effective, adjustable, and easy solution with me USR Banshee and Miniroc 1.2 kits and shouldn't be any different here since t' nose cone is friction fitted into the payload tube. Avast! For anyone new t' clusterin' and/or composite motors, ya bilge rat, the included AIR #3 document is a basic primer that explains t' concepts of friction fittin' motors, matey, ya bilge rat, and how t' properly wire and ignite clustered flights (also referred t' as parallel staging), me bucko, both o' which apply t' t' Weightlofter design. Avast, me proud beauty! Information is also included on how t' ignite multi-stage composite motor rockets.

T' first flight was on just a single motor, a F52-8T. Arrr! T' rocket be only covered in primer for this flight. Avast! I don't normally like t' fly unfinished rockets but I was anxious t' see how this rocket would perform. Avast! Ignition was instantaneous and on t' first time thanks t' t' Quickburst Twiggy ignitor used in place o' t' Copperhead that came with t' reload. Well, blow me down! Aye aye! With t' calm skies, boost was as vertical as I've seen a rocket go. Aye aye! Accordin' t' simulations, matey, I was expectin' about 1500' with t' F52. Ya scallywag! Arrr! I'd say that I got every bit o' that if not a hair more. Ahoy! Impressive!

U.S. Rockets Weightlofter The second flight came a couple months later. Avast, me proud beauty! I was extremely fortunate t' find someone gettin' out o' t' hobby and had a large selection o' BP motors that he sold t' me for real cheap. Avast! Among t' selection be 2 packages o' D11-P motors and 1 package o' E9-8 motors. Ahoy! Perfect! I contemplated goin' for broke with 6 D11-Ps surroundin' a central E9-8 but A) I did nay have a 7-motor clip whip at the time and B) I did nay want t' risk launchin' it from 7 Estes ignitors even if I would have had t' proper clip whip. Instead I decided t' be slightly more "economical" and get twice t' mileage out o' me motor supply by goin' with a pair flights on a trio o' D11-Ps around central E9-8 (the third flight is still pending...) Plus, I have a 4-motor clip whip. Begad! Now I only had to add some noseweight for stability but nay so much as t' hurt overall performance. Aye aye! A few large fender washers were screwed into t' base o' t' nose cone t' add about 2oz t' t' front end ensurin' stability for t' 3 D11-Ps and central E9-8 motors. Begad! I prepped all o' t' motors with maskin' tape at home the night before so I wouldn't eat up most o' t' launch day gettin' it ready. The motors were readied and t' rocket was put on t' pad. Ahoy! After several minutes of hookin' up t' motors with t' clip whip t' connect up all 4 motors, we were ready for lift off. Ya scallywag! With a healthy 12V source, ya bilge rat, shiver me timbers, thar be no hesitation with ignition from 4 standard Estes ignitors! All motors lit and away it went. Avast! While I don't burn many BP motors much anymore, matey, arrr, thar be definitely somethin' cool to be said about t' hiss o' a large BP cluster! T' Weightlofter cocked noticeably into t' stiff 10+mph winds.

Recovery:
T' bright orange 16" mylar parasheet (parachute) came preassembled and includes Keelhaul®©™ shroud lines and a snap swivel. Well, blow me down! Some interestin' information is given with t' parasheet as far as creatin' a deployment device (consistin' of a metal rin' or maskin' tape with all adhesive covered) t' allow t' chute to open more slowly, which isn't a bad idea with a large mylar chute. Begad! Arrr! I used a couple o' pieces o' maskin' tape with t' adhesive turned against each other to form t' ring. Begad! I attached t' chute (with t' tape rin' near t' chute) t' a small knot in t' shock cord near t' payload tube. Begad! A Nomex heat shield that I use betwixt several rockets was attached t' t' shock cord in lieu o' dog barf cellulose wadding. Avast! While thar be room for t' shock cord, parachute, beeper, and heat shield, thar wasn't room for anythin' else. I can't see using anythin' longer than t' AT 29/40-120 casin' in t' central motor mount.

Ejection for t' first flight was right at apogee as t' rocket just tipped over. Avast! T' mylar chute opened smartly but gently. Avast, me proud beauty! My rocket beeper went into chirp mode at that time and I watched it land within a hundred yards o' the pad. T' chute proved t' be a perfect match for this rocket. Ya scallywag! Arrr! There were a couple o' small holes burned into t' chute, matey, but they're nothin' that some clear tape won't easily patch.

On t' second flight, matey, me hearties, me hearties, t' windy conditions were hard enough on t' recovery system t' rip t' parachute right off t' shock cord. Blimey! T' snap swivel failed completely but t' rocket maintained a horizontal drag recovery (it was also aided by t' drag from me Nomex heat shield) down t' t' soggy grass field below. Blimey! As much as I want me rockets t' recover as designed, I was slightly thankful for t' chute failure only because t' rocket landed easily within 200ft o' t' launch pad (unlike me USR El Lubbo's flight that recovered over 1/4 mile away earlier in t' day from t' winds!) Nay a scratch or dent on the Weightlofter. Begad! Blimey! So in t' future I guess I'll have t' use a small nylon chute if I fly it in windy conditions...

Flight Rating: 5 out o' 5

Summary:
T' U.S. Arrr! Rockets Weightlofter is a super MPR cluster design that performs well with either a single AP motor or multiple BP motors. Ya scallywag! It also is a kit that requires some patience durin' construction because o' t' sheer number of parts. Avast, me proud beauty! With t' central motor mount bein' further aft than t' outboards, shiver me timbers, it may be difficult t' use flash pan ignition for 7 motor cluster launches so investin' in some good clip whips is probably t' way t' go. Well, blow me down! Arrr! For me, ya bilge rat, clip whips is definitely t' way t' go for 4 motor clusters!

Overall Rating: 5 out o' 5

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  • U.S. Rockets Weightlofter By Nick Esselman (June 30, 2008)

    I took a big jump with my second U.S. Rockets' rocket, from the minimum diameter Fire and Forget to the seven (7) motor cluster Weightlofter. I've have been enjoying various clusters over the past year or so, but usually 2 or 3 motors. To date, my Phoenix Mighty Kat has the most clustered motors; 8 of them. So, I was looking forward to the Weightlofter for comparison sakes. U.S. Rockets (USR) ...

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