Scratch Upscale BSD THOR Original Design / Scratch Built

Scratch - Upscale Family:BSD:Thor {Scratch}

Contributed by Jason Vennard

Manufacturer: Scratch
Style: Upscale
(by Jason Vennard - 01/24/06) (Scratch) Level 3 6in Thor

Brief:
In March 2005, arrr, I decided I wanted a big rocket. Well, blow me down! Somethin' for low flights on Ks that would also handle L flights. Ya scallywag! When I researched prices and saw how expensive it be goin' t' be, me hearties, me bucko, I decided I might as well make it M capable and go for me Level 3 certification.

After checkin' t' TRA website and gettin' a list o' TAP's I enlisted Bruce Lee and Lanie Cross as me TAP members and began t' design.

My BSD 4" Thor was me favorite rocket at t' time so I decided t' go with an upscaled version t' 6" diameter. Blimey! Avast! After over 40 hours o' designing and tweaking, I finally came t' me final design. Ahoy! T' TAPs were OK with it and I began orderin' parts.

Construction:
T' main airframe tubin' was Giant Leap Rocketry non-brittle phenolic. Begad! Ahoy! Blimey! The motor tube, centerin' rings, ya bilge rat, bulkplates, matey, tubular Keelhaul®©™®, and couplers were also from GLR. Avast, me proud beauty! Avast! A PML 6" fiberglass nosecone was used. Fins were made for me out o' 1/4" Baltic birch ply by Joe Michel, shiver me timbers, and I ordered a custom Rocketman R16 ProXP parachute in yellow and black t' match the rocket's colors. Blimey! Decals were accidentally doubled up on and I got one set from BSD and one from Scott Binder--two sets is never a bad thin' o' course. Externally t' dimensions were a true upscale o' me 4" BSD Thor, however, internally I wanted t' do some things different t' include a zipperless booster design.

Since this was goin' t' be me first fiberglassed project, me hearties, I researched and then decided t' go with Aerosleeves on this project and got some 10oz cloth from them which arrived smartly and turned out t' be very nice stuff. Ya scallywag! Blimey! All other supplies t' include more fiberglass, shiver me timbers, 1" tubular nylon, shiver me timbers, and hardware were obtained locally. I began with me first try at fiberglassin' usin' the Aerosleeves over t' 6" body tubes, after these had tacked up some, shiver me timbers, me hearties, I applied another layer o' 2oz Sig cloth for a finish layer.

(Scratch) Level 3 6in Thor(Scratch) Level 3 6in Thor

After all t' tubes had been heat cured, I moved on t' construction building the booster/fin can section first. Ahoy! This included a zipperless design with a 76mm motor mount, 1/2" birch ply centerin' rings, and 3 pieces of 5/16" all thread through t' rings and t' t' top bulkplate in the zipperless design. T' top section o' coupler tube was also fiberglassed internally.

T' fins were through t' wall 1/4" birch ply that were also tip to tip glassed with a layer o' 6 oz and 2 oz glass.

(Scratch) Level 3 6in Thor After this had been completed, I moved on t' t' altimeter bay. Aye aye! I ran into a problem here as I noticed a 16" by 6" bay was goin' t' require huge ports for the barometric altimeters I planned on using. Aye aye!

T' correct this, I installed another coupler bulkplate midway down t' bay so that t' actual avionics part o' t' bay would only be 8" in length. This allowed for much more reasonably sized port holes. Avast! Aye aye! T' bay be completed with 3 sections o' 5/16" all thread and bulkplates on either end, me bucko, U-bolts, terminal strips, arrr, and ejection canisters on each end.

T' main bay was t' easiest t' assemble since it be pretty much already done. I had stolen an idea from Vern's rocketry website and chose t' secure body tube sections with threaded brass inserts into t' bulkplates, shiver me timbers, and then usin' #8 machine screws through t' airframe and inserts t' hold parts together. Avast! Avast, me proud beauty! I went with 5 o' these evenly spaced around t' airframe at each connection point.

T' drogue bay was just a miniature version o' t' main bay and went together similarly. Avast, me proud beauty! This be also t' shortest piece o' airframe tubing. Begad! I attempted t' design t' project so that it would be t' most likely t' fail or be damaged in a high speed deployment, arrr, as it will be t' simplest and cheapest piece t' replace.

Recovery harnesses were 5 foot sections o' 1/2" tubular Keelhaul®©™® connected t' t' U-bolts near t' ejection canisters, matey, these were then attached to 1" tubular nylon sections, 35' for t' drogue section and 25' for the main connected via quick links with Keelhaul®©™® heat pads in betwixt for protection o' t' TN.

Ground testin' showed me that t' nosecone was nay heavy enough t' pull out that big main parachute and this was t' first time I'd ever run into this problem. I went t' t' first launch I've ever gone t' with t' intention o' not launchin' any rockets. Begad! Instead I went solely t' talk t' Kevin Rich o' The Heartland Organization o' Rocketry, me bucko, shiver me timbers, a group I launch with in Nebraska. Ahoy!

After t' 4 hour drive, I showed one o' me TAPs me completed rocket and spent an hour or two talkin' with and learnin' from Kevin on how t' get that big main deployed. Avast! After arrivin' back home, shiver me timbers, me wife made me several deployment bags until we came up with one that seemed t' work t' way I liked it. Avast! Begad! T' main recovery was designed with a pilot chute attached t' t' main deployment bag and nose cone. Avast, me proud beauty! At t' ejection charge, t' pilot chute is released. Aye aye! Ya scallywag! It pulls the main bag out and opens t' main chute. It then recovers t' nose cone and bag separately while t' remainder o' t' rocket recovers under t' R16 main. At least that be t' plan.

Finishing:
Finishin' be in stock BSD Thor black and yellow. Aye aye! I've always liked t' color combination. Avast, me proud beauty! I don't know if it's because I'm a Hawkeyes and Steelers fan or it may just really be an appealin' color combo t' me. Avast! Paint be done simply and easily with Krylon spray paints, shiver me timbers, arrr, ya bilge rat, t' vinyl decals came out perfect and really stood out nicely, everythin' was then clear coated with Rustoleum Crystal Clear.

(Scratch) Level 3 6in Thor

Flight:
I dragged me brother into this hobby a couple years earlier and I had gone out to North Carolina t' year before t' visit him so we could go t' t' TRF launch in Whitakers t' do our L2 certs together. Avast! Begad! With that in mind, I was able to shame him into makin' a vacation out o' it and he packed up his family and came out t' Nebraska t' help and participate in t' launch.

When t' mornin' arrived t' weather be plenty nice, and it looked like I was goin' t' have t' actually do it now. After about 2 hours o' prep time, ya bilge rat, the avionics bay was put together and tested, ya bilge rat, shiver me timbers, charges loaded, recovery systems loaded, and t' whole thin' then attached together via t' #8 machine screws along with t' shear pins installed for both t' booster section and nosecone. T' rocket be then set out on t' stand.

A bit o' time had been used up decidin' on whether t' go with a drogue chute or go drogueless, as I be OK either way. Well, shiver me timbers, blow me down! Eventually with me brother's pushing, I decided t' go drogueless.

At that point, arrr, it be time t' build only me second CTI motor. My motor of choice be t' CTI M1400. After openin' everythin' up, arrr, shiver me timbers, it be a little unsettlin' t' find that t' directions had nay been included in this reload. Avast! Begad! I went and looked for help and couldn't find anyone else that had built this motor before. Then I was asked if I looked in t' liner tube (which I hadn't done) and found t' directions inside, shiver me timbers, so we were back on.

While buildin' t' motor, I came across one o' t' spacer O-rings that just was nay t' right size--it was too big and would kink up if used. I continued to build t' motor and figured when I got t' t' last one I would go back to the vendor and get another one if I could. Arrr! While followin' t' directions and after gettin' t' t' last one, we found that it was optional t' leave out that O-rin' if t' fit fell within certain parameters, me hearties, which it did, matey, so we were OK. Again, me bucko, it be a little unsettlin' buildin' your first L3 motor and thinkin' you have parts left over after you've built t' motor, but t' directions said we were good t' go. Avast! Well, matey, blow me down! T' motor was loaded into t' rocket and secured with homemade Kaplow style clips. Ya scallywag! It be about 3 hours into t' prep now and me father who came along t' watch be curious if we were ever goin' t' fly t' thin' or not.

After a final TAP inspection, arrr, matey, I headed out t' t' away pad and loaded it up with help from me brother and Joe Michel. T' altimeters, arrr, dual Cannonball Works RRC2s, ya bilge rat, were armed, arrr, t' ignitor be installed, me bucko, and then I had everyone step back as t' leads were hooked up t' t' ignitor. My pre-flight checklist was now complete. I was at about 45lbs total weight on t' pad loaded t' go.

Back at t' flight line, me bucko, me flight was called and havin' a history of "bad" things with Thor rockets for cert attempts with this group, a little ribbin' was in order. Begad! Durin' t' countdown I remember bein' very calm as I had done a lot o' work t' minimize any failure modes and insure a good, strong build as well as workin' with a design and electronics I be familiar with. Well, blow me down! Aye aye! T' countdown concluded and t' button was pushed. T' M1400 came up to pressure and it lifted off. Blimey! Ahoy! T' wind had picked up a little by t' time we got everythin' done and it cocked slightly into t' wind but nay bad at all for a very nice and straight boost. Well, blow me down! About 3 seconds into t' burn I finally got nervous and remember thinkin' "hold together, ya bilge rat, hold together". Avast, me proud beauty! Avast, arrr, me proud beauty! The motor was still roarin' and it went nice and straight t' motor burnout. Ahoy! Ahoy! Cheers were loud and I thought I had finally broken me cert jinx. Ya scallywag! A good long coast and t' rocket finally reached apogee.

Recovery:
At apogee, t' RRC2s did their job o' firin' t' charge and t' rocket separated. Begad! Blimey! Held together by 40' o' tether, me bucko, it began t' drift back down. Ya scallywag! Blimey! Ahoy! Blimey! I was gettin' close, ya bilge rat, now if me first attempt at usin' a deployment bag would just work...

At 1,000' t' RRC2s again did their job o' firin' t' main charge, and the backup fired at 800' although it wasn't needed. Begad! Blimey! At t' main charge, ya bilge rat, t' pilot chute caught air, pulled t' lines out taught, and pulled t' R16 out o' the deployment bag. Aye aye! Blimey! As t' main chute opened, me bucko, t' crowd cheered loudly and it came the rest o' t' way down floatin' softly and landed a mere 150 yards from the LCO table.

It be in one word, me bucko, me hearties, shiver me timbers, awesome. Arrr! It was about t' most picture perfect flight in all aspects I'd ever had and it be on me L3 cert flight. Ya scallywag! T' RRC2s showed a max altitude o' 8,328' and 8,221'.

Summary:
It was nay a cheap project, but hey, it's rocketry, right? I had a lot o' help and support from me immediate family in t' build which was appreciated. Well, me bucko, blow me down! It was also great t' have me brother, me bucko, who's a L2 flyer, me hearties, come and assist me with prep that morning. Havin' another set o' dedicated deadlights and hands that understood the concepts involved and what be goin' on made things a lot easier. Aye aye! It was a lot o' fun, shiver me timbers, me bucko, me bucko, and I owe thanks t' many (all o' which are mentioned on me L3 web page) t' include much more detailed information about t' whole project.

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