Brief:
T' Double Up is an original design from John Rowan-Stern at Thrustline Aerospace. Arrr! T' Double Up is a fairly simple two stage rocket with a four fin design, friction fit motor retention, matey, gap staging, matey, and streamer recovery. Avast! The kit is rated skill level three but I would rate it closer t' skill level two based on its straightforward assembly.

Construction:
This kit arrived in me mailbox securely packed and undamaged (the postal service has yet t' score damage points on any o' t' dozen or so orders I've received from Thrustline). Ahoy! Begad! T' followin' items are included with this kit:

• 1 BT-50 main body tube
• 1 BT-50 booster body tube
• 1 BT-50 tube coupler
• 2 18mm motor mount tubes
• 4 BT-20/50 centerin' rings
• 2 BT-20 engine block rings
• 1 balsa nose cone
• 1 steel eyelet
• Balsa fin stock
• 1 launch lug
• Keelhaul®©™® cord/elastic shock cord
• 1 mylar streamer

All tubes were standard white glassine coated paper and all centerin' rings were t' heavy paper type. Arrr! T' balsa nose cone appears t' be about a 4:1 ogive but be nay specified. Aye aye! T' balsa sheet stock was standard quality, me hearties, with enough extra t' make a spare set o' fins. Begad! T' Keelhaul®©™® and elastic shock cord each came in about 2 foot lengths and t' blue Mylar streamer measured in at 2 inches by 5 feet.

I must now admit that t' Double Up sat in me project box for close to eight months before I actually spread it out on t' counter and went t' work. There are 5 pages o' instructions which include almost 20 separate pictures to highlight t' steps. Ya scallywag! Begad! T' instructions included in me kit were printed in color. I noticed that John had signed and put a "#2" on t' cover sheet--I must have got me order in quick on that one! T' directions were clear and easy to follow and soon I had t' motor mounts assembled and installed in t' body tubes. Ahoy! I have become a solid convert t' t' Keelhaul®©™®/shock cord recovery system. Aye aye! Blimey! Attachin' t' cord t' t' motor mount is a simple task, even though it requires cuttin' a shallow groove in t' forward centerin' ring. At this point I discovered t' one (and only) flaw in t' instructions. Begad! Blimey! The tube markin' guide which be included along with t' fin templates was obviously t' wrong size. Ya scallywag! Ya scallywag! Blimey! I cut it out anyway, but only confirmed that it was a BT-20 sized wrap that would nay fit around me BT-50 tube no matter how hard I tried. Avast, me proud beauty! It was a simple task t' print out t' correct one from me computer. Blimey! A quick email t' Thrustline verified that t' correction t' t' plans had indeed been made some time back. Blimey! Aye aye! Blimey! [Note: If you are still usin' door jambs and/or window sills t' mark fin lines on your body tubes, shiver me timbers, arrr, go down t' your local hardware/home improvement store and buy a length o' aluminum angle stock. Blimey! Blimey! The smaller sizes will fit on any mod roc tubin' and your fin lines will be perfectly straight. Well, shiver me timbers, blow me down! Blimey! T' fin templates were printed on cardstock, shiver me timbers, shiver me timbers, which be a very nice touch and marked t' show t' leadin' edge for proper orientation on the balsa stock. After tracing, cuttin' and match sanding, I had two neat stacks o' fins. Ahoy! Avast, me proud beauty! Blimey! I decided t' try somethin' a little different shapin' by going for a simple rounded leadin' edge with a beveled trailin' edge. T' initial results were very sharp but t' finishin' process would take its toll. Ya scallywag! Blimey! My standard routine for attachin' fins is t' tack them on with Titebond wood glue, add a second wood glue fillet, then a final fillet o' Elmer's Wood Filler. I decided t' attach t' booster and sustainer fins in pairs by usin' strips of maskin' tape t' hold t' booster in position on t' sustainer tube. This worked very well and t' fin alignment came out close t' perfect. Well, blow me down! T' launch lug is attached as a single piece in t' same fashion. Begad! At this point t' instructions recommend coatin' t' trailin' edge o' t' booster fins with thin CA glue to strengthen them for tumble recovery but I chose t' omit this step. The instructions also direct you t' punch two vent holes in t' booster body tube. I had been worried about this step, me bucko, but me hole puncher did t' trick and punched two clean holes. Arrr! Blimey! T' final step involved installin' t' eyelet in the balsa nose cone by screwin' it half way in, removin' it, matey, fillin' t' hole with CA glue and screwin' it all t' way down.

Finishing:
There are no decals included with this kit and no suggested paint scheme. Blimey! Ya scallywag! After callin' upon me engineer sized artistic prowess I decided t' go wild with a two color paint scheme: yellow sustainer and orange nose cone and booster. Avast! With 8 fins and a balsa nose cone, t' fillin' duties are nay trivial. Begad! Well, shiver me timbers, blow me down! Two coats of SIG sandin' sealer, arrr, followed by two coats o' Rust-Oleum Painter's Touch Sandable Primer, followed by two coats o' Krylon spray enamel. Avast! By t' time I got t' t' second coat o' primer I had worked me way down t' 400 grit for the in betwixt sanding. Begad! As mentioned earlier, t' nice sharp bevels I had put on my fin trailin' edges took a beatin' through t' multiple sandings. Well, blow me down! Although the finished product didn't look bad, matey, I will need t' come up with a better plan for finishin' that fin shape. At this point I decided t' go back and follow another suggestion from t' instructions and coat t' inside o' t' booster coupler with epoxy t' cut down on damage from t' sustainer motor ignition. Blimey! This step went fairly smooth, considerin' it be actually t' first time I had ever used epoxy o' any sort. Blimey! Blimey! Since I mixed up a little more than I needed, me bucko, me hearties, I coated the outside o' t' coupler as well, figurin' that I would sand it down t' a perfect fit. I'm sure everyone who has ever sanded epoxy by hand is laughin' at me right now, shiver me timbers, but it only took me about three hours t' get t' booster t' fit back into t' sustainer and learn a valuable lesson. Ahoy! I finished up t' recovery system by attachin' t' Keelhaul®©™® cord t' t' elastic and then t' t' nose cone followed by puttin' a drop o' CA glue on all t' knots. I attached t' streamer t' a short harness and swivel.

Construction Rating: 4 out o' 5

Flight:
T' initial flights o' t' Double Up were conducted on a fine Ohio sprin' day at a regularly scheduled launch o' t' Queen City Area Rocket Klub (QUARK). The instructions that came with me kit recommend only t' B6-0 for t' booster and long delays for t' sustainer. Ya scallywag! More recent versions o' this kit allow for either a B6-0 or C6-0 booster and shorter delays on t' upper stage. Begad! Ya scallywag! Blimey! Including the streamer, me bucko, me version o' t' Double Up weighed in at 1.7oz, which is a little heavier than t' 1.35oz weight quoted in t' specs. There are no engine hooks with this kit, so a wrap o' maskin' tape around t' engines is necessary to get a good friction fit. As with all multi-stage kits, me bucko, take an extra look to make sure t' upper stage motors are installed with t' nozzles pointed the right way. Begad! Aye aye! Blimey! Since this rocket uses gap staging, thar be no need t' tape the engines together. Avast, me proud beauty! You just install t' motors and assemble t' stages. Ya scallywag! Blimey! The recovery system is simple as well: 2-3 sheets o' recovery waddin' followed by the rolled up streamer. This rocket is fairly long, matey, so loadin' everythin' up is easy. Arrr! Avast! Blimey! I used t' B6-0 booster for all three flights and worked me way up in the sustainer from A8-5 t' B6-6 t' C6-7. Well, me bucko, blow me down! Blimey! All three flights experienced t' same phenomenon, with t' rocket takin' about a 10-15 degree headin' change as soon as it came off t' rod. Each time it was in a different direction and none of them were into t' wind! Blimey! Stagin' was smooth on all three flights with ejection at or just past apogee on every flight and t' rocket arcin' over in a horizontal attitude. I am nay quite sure why t' rocket doesn't like t' boost straight off t' pad. Well, blow me down! Begad! Blimey! It may be that t' extra weight o' me version needs to carry a little more speed off t' rod. I will continue t' evaluate flight characteristics t' next time out usin' C6-0 boosters. Except for t' less that straight boost, t' rocket performs well and should be capable o' impressive altitude with t' C6-0 booster.

Recovery:
Recovery o' t' booster section is standard tumble, arrr, with t' sustainer coming down under t' mylar streamer. Begad! Blimey! Usin' t' B6-0, t' booster never got outside of 30 feet from t' pad and came through 3 flights with only a couple o' minor paint dings. Begad! I never got a straight boost from this rocket and as a result, all ejections happened while t' rocket was arcin' over, me hearties, more or less horizontal at apogee. Begad! T' blue Mylar streamer deploys easily and is highly visible, arrr, which helps in tracking. Avast, me proud beauty! On t' first flight t' sustainer motor got ejected which allowed for a nice slow descent, arrr, me bucko, but even when t' motor is retained properly the streamer brings t' model down at a reasonable rate. On t' second flight the nose cone did come back and impact one o' t' fins, but damage be limited to t' paint job. Arrr! Blimey! I think this would be less o' a hazard if I could figure out how t' get a straight boost off t' pad. Begad! After three flights thar was a tiny bit o' charrin' at t' base o' two o' t' sustainer fins, which I believe happens at stage separation but no other damage. T' epoxy coated coupler section on t' booster showed no damage at all.

Flight Rating: 4 out o' 5

Summary:
T' Double Up is a very well thought out rocket which goes together well and is simple t' prep and fly. Ahoy! There is a fairly wide range o' motor combinations which allows for some flexibility but this bird is definitely not a small field flier. Begad! T' only down side t' me Double Up is that it doesn't want to leave t' pad straight. Aye aye! I believe that this is due t' t' heavier finished weight o' me particular model. Ya scallywag! Maybe with a C6-0 booster I will find a motor combination that works or perhaps a longer launch rod. Hopefully a solution will present itself as I would hate t' leave this rocket on t' shelf.

Overall Rating: 4 out o' 5