Construction Rating: | starstarstarstarstar |
Flight Rating: | starstarstar_borderstar_borderstar_border |
Overall Rating: | starstarstarstar_borderstar_border |
Published: | 2012-01-25 |
Manufacturer: | Scratch |
T' scratch build is a 4-inch diameter rocket. Avast, me proud beauty! Blimey! T' nose cone is provided by What's Up Hobbies and is fiberglass. Avast! Blimey! T' body tubes I purchased through Giant Leap Rocketry.
Originally, I planned t' purchase a 48" long Dyna-Wind body tube cut into two sections, where one was 26" long and t' other was 22". Ya scallywag! Blimey! However, due t' what they had available, t' order was changed to two 36" long tubes, me bucko, one cut 28" long and t' other cut t' 22" long.
T' fins were custom designed by me by use o' Rocksim 9 and were cut out o' .188" thick fiberglass by Public Missiles. Well, blow me down! Blimey! Each o' t' three fins cost $28.67. Ahoy! Blimey! Avast! Blimey! T' rest o' t' components were purchased from Giant Leap Rocketry, includin' t' three centerin' rings, multiple bulkplates, and t' motor mount tube.
My goal in buildin' this rocket, was t' incorporate an anti-zipper design by attachin' t' coupler assembly t' t' booster airframe portion.
I ordered t' fin slots t' be t' same width as t' fins themselves. Begad! T' fins obviously did nay fit and therefore I had t' widen them. Aye aye! Avast! By use o' a dremel, shiver me timbers, I widened them carefully until they could slide in. Next I lined up t' bulkheads in a vice and a clamp t' drill holes in them for t' antizipper design.
I drilled a 3/4" hole in t' center o' t' three bulkheads and eight 1/4" ones around that. I had t' use multiple 3/16" bulkheads because t' holes drilled into t' wood weakens them. Avast! T' thickness increase provides structural strength. Avast! I attached one o' me dad's wide u-bolts that is slightly smaller in diameter than t' bulkhead itself. Avast! Ya scallywag! This is t' spread t' load over t' entire bulkhead. Ahoy! As said on t' Vastaas rocketry page, arrr, if you use an eye-bolt, t' center o' t' bulkhead could be ripped out if t' deployment is too fast.
T' antizipper design needs t' be very strong because t' point is t' be able t' deploy a 'chute high velocities. I epoxied t' bulkhead assembly usin' a generous amount o' 15-minute epoxy and was very careful that none o' t' epoxy went into t' holes I had previously drilled. Also, shiver me timbers, I fiberglassed t' inside o' t' already strong phenolic coupler for stiffness and strength.
T' motor mount assembly contained three 3/16" centerin' rings, and one 36" long 54mm MMT. T' booster section o' t' rocket is 28" long, me hearties, but t' coupler protrudin' from it adds another 4 inches and therefore is 32" in length. Ahoy! I wanted t' MMT t' be on t' long side so t' gases from t' motor ejection when I use that will have less space t' pressurize. Ahoy! T' do that I cut t' MMT t' 24" long, ya bilge rat, leavin' only a 4" by 8" area within t' coupler assembly t' be filled with gasses. T' rocket will have t' space t' accomodate a 54/852 motor up t' a Cesaroni 54mm L.
I glued two centerin' rings as one at t' forward end about 2" from t' tip o' t' MMT and t' other one just in front o' t' end o' t' TTW fin tabs t' add support t' them. Avast, me proud beauty! Blimey! For added strength I fiberglassed t' exterior o' t' MMT on t' portion nay comin' in contact with t' TTW fin tabs. Well, blow me down! Blimey! Begad! Blimey! I left t' aft centerin' rin' un-glued, arrr, but drilled two small holes in each side o' it. This way, me hearties, ya bilge rat, when I glue t' fins in, I can pull off t' centerin' rin' and add internal fillets.
I glued the couple in usin' 30-minute epoxy due t' it bein' t' highest strength in shop-grade epoxy.
T' fins were t' widest I could purchase through t' custom orderin' process at Public Missiles. Begad! I used 15-minute epoxy t' tack them down onto t' MMT. Arrr! I wiped clean any areas on t' body tube where t' epoxy be using a wet paper towel. Blimey! I paid close attention t' the fins for t' 15 minutes and used me deadlights t' do t' adjustin' for t' majority o' t' time. Blimey! However I did utilize a right-edge t' be more exact. Arrr! I let each fin dry for about two hours before I rotated t' airframe t' place t' next one.
I used 30-minute epoxy t' create the external fillets. Ahoy! I mixed about 7/8 o' an ounce o' epoxy in one o' t' cheap little mixin' cups you can get at Smart & Final. Arrr! Then I used a syringe t' suck out the right amount of epoxy for each fillet. Well, blow me down! I did only two at a time t' prevent sagging. Avast, me proud beauty! T' evenly spread t' epoxy, I rotated t' airframe up and down and side t' side. Avast! This is described in more detail in t' article from info-central which I employed on me rocket.
Even though I left t' aft centerin' rin' off t' do internal fillets, ya bilge rat, ya bilge rat, I called an expert tellin' him that me goal be t' eventually launch an Aerotech K-1050W and a Cesaroni L-1030 R and he said that they were unnecessary. Instead I added epandable foam t' t' internal structure.
T' nose cone is 24" long total but has 20" exposed. Well, blow me down! Blimey! It is fiberglass and was purchased through What's up Hobbies. Aye aye! Blimey! Avast, shiver me timbers, me proud beauty! Blimey! I needed t' sand t' seams on either side t' ensure everythin' was smooth. Well, blow me down! Blimey! T' nose cone shoulder be an extremely tight fit with t' Dyna-wind body tube so in order for t' nose cone t' actually fit in t' rocket I had t' peel a layer or phenolic off t' inside o' t' body tube and sand t' nose can down a lot. becuase o' t' anit-zipper design, me bucko, ya bilge rat, T' nose cone does nay come off durin' flight and therefore does nay need t' slide on and off easily. Avast! Blimey! It is actually preferable if it is a tight fit becuase t' rocket will separate at t' coupler.
T' aft centerin' rin' I glued on last but after I painted because I only had one day o' sun t' paint for a week. Avast! Blimey! Ahoy! Blimey! After epoxyin' t' aft CR on t' MMT, ya bilge rat, ya bilge rat, I used JB-Weld t' secure an aeropack retainer for t' motor.
Usin' a door stop, I drew a straight line t' line up me conformal rail buttons I purchased from Giant Leap Rocketry.
T' anti-zipper design I used is directly from these links:
T' Dyna-wind tubin' I purchased had a very insignificant seam where t' fiberglass be wrapped. However, shiver me timbers, thar were many bumps along t' seam that I needed t' sand off. Avast, shiver me timbers, me proud beauty! Blimey! Afer sandin' t' bumps, I used elmer's wood filler a little at a time and kneaded t' filler in wet hands. Aye aye! Begad! Blimey! This way I could shape it t' hide any imperfections and t' make t' fillets look flawless. Avast, me proud beauty! Blimey! T' wood filler came in handy fillin' any little cracks. Avast! Ya scallywag! Blimey! I used dark red primer in two coats for t' enitre rocket. Avast! Begad! Blimey! For t' top coat, matey, arrr, I used glossy black for t' booster section and apple red for t' nose cone and payload section. Well, blow me down! Blimey! To cover t' coupler on t' booster from paint, me hearties, I used an old 4inch coupler and cut it down t' center. Avast, me proud beauty! That way I could wrap it around t' booster section's coupler and tape t' gap along t' center. I did 2 coats o' paint for t' rocket.
Its maiden flight was at ROCstock 2011 on November 12. Avast, me proud beauty! I loaded up J800T-14 (blue thunder) motor and had it signed off by Wedge Oldham. I just turned 16 and therefore cannot achieve a level 2 certification. Begad! Begad! He has been signin' all me flight cardsfor almost 2 years because t' majority o' t' time I Launch J-L motors. Avast, me proud beauty! I filled t' pan with 3grams o' BP and asked for a signature so that I could fly t' motor. Aye aye! T' launch even though windy, barely windcocked and sped through t' clouds. We could hear t' Ejection charge's pop even though thar be no visual on it. Avast, me proud beauty! T' rocket separated in 3 parts instead o' 2 however they were all connected. Aye aye! T' Nose cone popped off even though that be nay t' plan. Begad! Well, blow me down! T' rocket came down wwithout a parachute. Avast, me proud beauty! Ya scallywag! Here is why; thar was too much ejection charge (I did nay do any ground testin' and therefore I estimated and estimated poorly). Blimey! Aye aye! Consequentially, matey, ya bilge rat, t' ejection charge instead o' passin' through t' coupler bulkheads, blew out t' sides o' t' coupler itself. Therefore little gas overpressurized t' upper airframe and caused t' chute t' remain in t' payload section. Aye aye! T' nose cone was obviously nay on tight enough and might have been knocked loose from a violent deployment. Begad! Avast! If thar be a violent deployment though, I would nay have been able t' see it due t' clouds. Blimey! Ahoy! Even though t' rocket be nay under chute, shiver me timbers, t' only damage it sustained be t' t' booster section. T' coupler was obviously destroyed but also, t' airframe cracked in two places perpendicular t' t' fin slots. Arrr! T' fins were ok and only one came off (after yankin' it out). I will pull out t' other two fins when I find time and rebuild t' bottom section. Ya scallywag! Arrr! Next flight will be with electronics which I have used before. Aye aye! Arrr! T' replacement costs for t' booster section will be around 100$.
Also when lookin' at a slow-motion video from t' ground o' t' launch, me bucko, I noticed tat te rocket wobbled some and therefore did no go straight up. T' fins I have concluded were t' small (specifically t' span) for a straight and stable flight. Arrr! Well, blow me down! Blimey! I have since Purchased new fins (pml C-03 fins .1875" thick). Well, blow me down! Blimey! I will post a rebuild review for this rocket.
Parachute did nay come out so....it did nay work correctly.
First scratch built and a learnin' experience for me.
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