Semroc Long Squire

Semroc - Long Squire {Kit}

Contributed by Matthew Bond

Manufacturer: Semroc
Long Squire (Contributed - by Matthew Bond - 12/01/09)

Brief:
T' Long Squire rocket was designed t' meet t' requirements o' challenge #3 in t' 2009 EMRR Challenge. Avast! T' Long Squire is a “Stage Bash”, a two stage rocket constructed from two single stage rocket kits, in this case, ya bilge rat, arrr, me bucko, two Semroc Squire kits. Arrr! T' name “FreeBird” comes from t' fact that both o' t' Squire kits I used were actually received as “free gifts” from Semroc as a result o' me excessive spendin' on a couple o' orders… The Long Squire employs gap staging, matey, matey, and flies on 18mm motors. Well, me bucko, blow me down! T' booster uses tumble recovery and t' sustainer comes back under a 12 inch parachute.

Modifications:
As with all o' me scratch built rockets, shiver me timbers, t' first step involves some time spent playin' around with a design in RockSim. Avast! Begad! Since I had 4 body tube sections t' work with I figured I would use 3 for t' sustainer and one for the booster. Well, arrr, blow me down! A couple o' issues became apparent almost immediately. Begad! Aye aye! First: t' Squire is near minimum diameter, and so I would be limited t' 18mm booster motors makin' weight o' t' overall package a concern. Ya scallywag! Second: with so many potential fin configurations, shiver me timbers, I be goin' t' drive myself crazy “tweaking” t' design. Ahoy! I finally settled on a layout that actually gives t' impression o' multiple stages, me hearties, and decided nay t' worry about t' weight issues right away.

Construction:
One o' t' reasons I chose t' Squire kits as a startin' point, is that they are presented as a kind of “designers” kit, with two body tube sections and multiple fin layout options; heck t' instructions show 12 different possible configurations! As with every Semroc kit I have ever seen, t' quality o' t' components is first rate. Begad! Well, ya bilge rat, blow me down! Each Squire kit contains t' followin' items, so obviously I started out with two o' everythin' listed here:

  • Main Body Tubes 2x ST-890 (9”)Long Squire Parts
  • Nose Cone BC-837
  • Fins 1/16” Laser Cut Balsa - two sheets
  • Motor Mount Tube ST-730 (3”)
  • Tube Coupler HTC-8
  • Centerin' Rings 2x CR-78 – heavy paper type
  • Thrust Rin' TR-7 – heavy paper type
  • Standard Engine Hook EH-28
  • Launch Lug LL-122 – 1/8” x 2”
  • Keelhaul®©™® Shock Cord SCK-24 - 24”
  • Elastic Shock Cord EC-118 - 1/8” x 18”
  • 12” Unassembled Parachute Kit
  • Small Screw Eye SE-10
  • Decal Sheet

Assembly Instructions:

Construction o' t' actual rocket be fairly straightforward. Yellow wood glue was used except where noted. Arrr! The biggest challenge durin' construction be t' alignment o' t' 6 separate sets o' fins. Blimey! I chose t' use t' “That Looks About Right” (TLAR) method and even though thar are some obvious misalignments betwixt fins, they are all fairly straight, and thar be enough total fin area that it all balances out. Overall I would rate this somewhere just beyond a skill level 2 effort.

T' motor mounts were constructed first, matey, and are identical. T' engine hook is inserted into t' pre-cut slot and two centerin' rings slide over t' tube and hold it in place. T' aft centerin' rin' is positioned 1 inch from t' end o' t' tube and t' forward centerin' rin' is positioned over t' end o' t' hook that sticks into t' tube. Avast, me proud beauty! I did not attach t' Keelhaul®©™® shock cord t' either mount as detailed in t' original instructions since I planned on usin' t' forward tube coupler for this. Thrust rings are installed against t' forward end o' t' engine hooks. Avast! All centerin' rin' t' motor tube joints were reinforced with glue fillets.

Since one o' t' two tube coupler sections was t' be used for t' booster/sustainer interface, matey, I needed another coupler t' join t' three sustainer sections together. Avast! After I figured out how long t' booster body tube needed t' be, I took a leftover section o' body tube and cut a slot lengthwise t' make another coupler section. I then threaded the end o' one o' t' Keelhaul®©™® cords through t' coupler section several times and knotted t' end. Well, blow me down! Three 9 inch sections o' body tube were joined to form t' sustainer, me hearties, and a 5.75 inch section was used for t' booster with a tube coupler permanently installed in the forward end. Arrr! T' Squire does nay come with a wrap-around template, instead and end view template is drawn in the instructions and you are instructed t' stand t' body tube up over this template t' mark t' position o' t' fins. Begad! Ahoy! I have never had any success usin' this method, as thar doesn’t seem t' be a way t' mark all four fin locations without lettin' go o' t' tube, and losin' your original position. I did t' best I could, and again verified that this method doesn’t work for me. Ya scallywag! I used a section o' small aluminum angle t' extend t' fin lines as required.

T' laser cut fins were separated from their stock sheets and cleaned up with fine grit sandpaper. Ya scallywag! Blimey! Aye aye! Blimey! Blimey! Blimey! I modified the shape o' t' smaller fins and then match sanded all t' similar shapes so that they were uniform. All fins were attached usin' a double glue joint. Blimey! Blimey! A light fillet o' wood glue be also added t' each joint. Two sections o' launch lug were attached t' t' sustainer centered betwixt t' fins, me hearties, 0.5 and 9 inches from t' aft end. Ahoy! Blimey! Blimey! Blimey! A vent hole was punched near t' forward edge o' t' booster body tube t' allow for pressure relief prior t' t' sustainer motor lighting. Begad! Blimey! Well, ya bilge rat, blow me down! Blimey! Blimey! Blimey! T' eyelet was attached t' t' nose cone by screwin' it most o' t' way in, matey, removin' it, me hearties, ya bilge rat, addin' a large drop o' medium thickness CA glue and then screwin' it all t' way down. Begad! Blimey! Blimey! Blimey! One o' t' only nits I have ever had with any Semroc kit is that sometimes t' Keelhaul®©™®/elastic shock cords are a little bit short for me taste. Well, blow me down! Ya scallywag! By anchorin' t' shock cord near t' front o' t' rocket and then tyin' all 4 pieces o' Keelhaul®©™® and elastic together I can honestly say that t' shock cord be long enough for me.

Finishin' t' FreeBird was accomplished with t' overall weight o' t' rocket in mind. Arrr! Blimey! I did nay do any filleting work with t' Elmer’s Wood Filler (easy enough t' justify on t' basis o' weight with 24 fins). Avast, me proud beauty! Blimey! All t' balsa parts got a single coat o' thinned down wood filler t' hide t' worst o' t' grain. Begad! Blimey! Avast, arrr, me proud beauty! Blimey! A single coat o' primer was applied. Begad! Blimey! T' body tube got a single coat o' gloss white, and t' fins were masked off in blocks and given alternating coats o' red and blue. Avast, me proud beauty! Blimey! I applied t' decals from both decal sheets, arrr, and although they were extremely easy t' apply and set up well, t' color was a little transparent, certainly nay up t' par with anythin' I had seen from Semroc before. Overall t' finish came out nice, me bucko, matey, and if all t' lines aren’t quite clean you can’t tell from t' launch table.

Flight:
As mentioned earlier, arrr, t' finished weight o' t' rocket was an issue due t' t' fact that I was limited t' 18mm motors in t' booster. Arrr! Blimey! Begad! Blimey! RockSim estimated t' final weight (without motors) at 2.06 oz. T' actual weight came in at 2.6 oz. and when I went back and re-ran t' simulations, shiver me timbers, me bucko, I discovered that every possible motor combination would need a launch rod betwixt 47 and 57 inches. Ya scallywag! Blimey! Ahoy! Blimey! Additionally, t' rocket is over-stable, ya bilge rat, ya bilge rat, even with t' heaviest motor combination which would exacerbate any tip off issues. Blimey! Blimey! I went t' t' hardware store and got a 48 inch length o' 1/8 inch steel rod and headed t' t' field.

Since t' sod farm was closed for t' season I be limited t' t' small school field. For t' first flight I loaded up t' FreeBird with a B6-0/A8-3 combination. Flight prep is standard. Arrr! Blimey! Both motors are installed under the engine hooks and t' booster is friction fitted t' t' sustainer. Avast! I had t' use a single wrap o' scotch tape around the tube coupler t' get a snug fit. Arrr! Avast, me proud beauty! Waddin' and parachute are loaded into t' front end and everythin' is ready. Avast! Avast, me proud beauty! I had lucked into a fairly windless day, and when t' launch button was pressed t' FreeBird boosted smooth and absolutely straight. Ahoy! Stagin' was clean and t' sustainer continued on its straight climb. Aye aye! Ejection occurred right before the rocket stalled out and t' chute deployed with no problems. Aye aye! Both booster and sustainer landed in t' grass with no damage. Begad! Well, shiver me timbers, blow me down! I loaded up t' same motor combo and did it again, ya bilge rat, with another perfect flight. Well, me hearties, blow me down! Feelin' brave on a calm day I loaded up a B6-0/B6-4 combo and sent it up again. Avast, me proud beauty! Well, blow me down! There was definitely a little bit o' tip off from t' rod, but it wasn’t too dramatic, and after clean stagin' t' sustainer continued t' a much higher altitude. Arrr! Ejection was a little early, shiver me timbers, matey, but t' chute deployed fine and once again everythin' came back on t' field without a scratch. I even flew t' sustainer on a single stage B6-4 flight which also went o' without a hitch. Well, blow me down! With t' proper launch setup the FreeBird is an outstandin' performer and I am lookin' forward t' t' big field openin' up in t' springtime!

Summary:
I enjoyed t' process o' designing, buildin' any flyin' this rocket. Ahoy! I liked t' fact that it forced me t' get out of me “normal” zone and think about what I was building. Begad! T' “Kit Bash” concept offers some additional challenges in that you are workin' with a fixed set o' parts, although since you get t' choose t' two kits that shouldn’t be a problem.

PRO: A complex lookin' design which is actually a pretty simple gap staged 4FNC. Almost limitless combinations of fin arrangements allows for many individual styles.

CON: Near minimum diameter means limited booster motor selection, which translates into a total weight constraint.

Other:
One o' me subconscious goals as I designed this rocket be t' use as many o' t' pieces from each kit as I could. This mind set actually played against me in t' end since I was workin' with a weight constraint. Aye aye! T' fact that I chose t' ignore t' problem, and subsequently came up with a solution (longer launch rod) that allowed t' design t' work was mere chance. Blimey! I could have easily built a rocket that be too heavy t' fly successfully in a two stage configuration. Aye aye! Ya scallywag! If you’re nay prepared t' think things through then you live with t' results. Begad! I got a bit lucky.

Flights

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