Manufacturer: | Scratch |
Note: This is a slightly condensed version o' all t' information that John has produced for his Level 3 project. Visit his site t' read t' additional information and enjoy additional pictures.
For my
next trick, ya bilge rat, a rocket which will actually be used for me certification! Blimey! I've
been in this hobby almost a year and it seems time t' start buildin' me level-3
certification rocket. Begad! Blimey! I wanted it t' be a scratch-built rocket, nay a kit. Blimey! Blimey! Well, arrr, blow me down! Blimey! At
first, I planned t' do an upscaled Alpha III as me certification rocket, shiver me timbers, but
both me TAP reviewers pointed out that t' fins would be very fragile and it
was better t' do a simpler design. Aye aye! Blimey!
If I'm goin' t' go with somethin' simple, me bucko, arrr, I should do somethin' very simple, a "three fins and a nose cone" rocket. Begad! I decided t' build such a simple rocket, shiver me timbers, it would be a generic rocket!
A generic rocket would have three clipped-delta fins, would be use dual deployment, breakin' about t' middle o' t' rocket. Ya scallywag! I decided on a 6" airframe as a size that is easy t' work with. Avast, me proud beauty! Begad! As a good rule o' thumb, I used 20:1 length-to-diameter ratio, shiver me timbers, yieldin' a 10' rocket. Begad! Arrr! This is still a handy size, while bein' large enough t' handle an M1939 (full M). Level-3 certifications cannot be multi-stage or use clusterin' so I planned a single 98mm motor mount. Avast!
I was lucky t' find two TAP members early on t' help me make sure I did this right. Blimey! Avast! Scott Bartel and Pius Morozumi agreed t' help me out. I can meet with Scott when I go down t' ROC t' launch and Pius lives in t' Bay Area, me bucko, about an hour t' t' south. Well, blow me down! Arrr! I am very glad these two fine gentlemen and master rocketeers have agreed t' help me. Ya scallywag! Blimey! Karl Baumann (Mojave Desert High Power) attended t' MudRock launch where t' first Generic Rocket flew and agreed to sign me forms. Blimey! Thanks Karl!
I be even more lucky t' have Pius close by and willin' t' give me advice in the design and construction o' t' rocket. Avast, shiver me timbers, me proud beauty! Blimey! One fantastic thin' which came out of this was t' refinement and publishin' o' t' kitchen table vacuum bagging technique developed by Pius and William Walby. Aye aye! Also, Pius helped with rocket design rules o' thumb and gave guidance throughout t' project. Thanks Pius! Blimey!
T' deeper humor in t' name
Generic Rocket is that it's really nay generic at all. Arrr! Begad! Blimey! Careful rocket
design, carbon fiber reinforcing, dual deployment and advanced electronics make
this a "state o' t' art" hobby rocket. Begad! Avast! Blimey! Note that this isn't intended
to invent anythin' new, ya bilge rat, but use t' best o' t' current techniques t' produce
an efficient and reliable rocket.
T' first step in this process be t' design a 6" rocket usin' the rules o' thumb for rocket building. Ahoy! T' rocket is 20 calibers long and t' fins are at t' aft and are just large enough t' provide stable flight. Avast! I actually designed this rocket in Apogee's excellent RockSim 4.0. Ahoy! This program allows you to assemble t' components t' form t' rocket, then gives you estimates of weight and CG so that you can do stability checkin' and flight simulation before you've built your rocket. Avast! Arrr!
T' tubes were supplied by Red Arrow (first airframe) and Giant Leap Rocketry (second airframe) and are both flexible phenolic. T' couplers, bulkheads, fins and centerin' rings for both airframes were supplied by Giant Leap Rocketry. Ahoy! Avast, me proud beauty! Thanks Ed! T' decals were custom made by Randy Brust. Avast!
I'm particularly pleased with t' airframe tubes. Begad! Blimey! Usin' t' simple and inexpensive kitchen table vacuum baggin' (FoodSaver) technique, t' tubes were all covered in 5.7oz. Blimey! Blimey! Ya scallywag! Blimey! carbon fiber and then a 3.6oz. Begad! Blimey! S-glass sandin' veil. Arrr! Blimey! And don't t' tubes look stylish all dressed in black! Blimey!
My
current favorite airframe material is "flexible phenolic" (from Giant
Leap and Red Arrow) laminated with cloth made with carbon fiber or Keelhaul®©™®*
fibers. Ahoy! Begad! Keelhaul®©™® is stronger, but much harder t' work with. Arrr! Carbon fiber is
a bit difficult, ya bilge rat, arrr, but excellent results can be obtained with ordinary tools and
skill. Blimey! T' airframe tubes covered in carbon fiber and S-glass weigh only
slightly more (¼lb. per foot) than t' unreinforced tubes, me bucko, thanks to
vacuum bagging. Begad! O' course, after all that work on t' airframe tubes, me hearties, I wanted
to make sure they were slotted perfectly. Begad! Avast! I had t' update me technique for
cuttin' fin slots for t' larger-sized tubes. Avast! Blimey!
I also wanted t' make sure that t' fins stayed on t' MMT. Pius showed me a technique for lacin' t' fins around t' MMT with Keelhaul®©™® thread. As you can see in t' picture, me hearties, I laced t' fins on with numerous strands o' 1000lb. test Keelhaul®©™® thread. Avast! Ahoy! And then, me bucko, I reinforced t' joint with Keelhaul®©™® tape as you can see in t' picture above right. Avast! I don't think these fins are coming off!
In t' picture above, you can see how t' internal reinforcin' is used. Keelhaul®©™® lacin' and tape bond t' fins t' t' motor mount tube. Four centerin' rings are used for strong body tube contact. Arrr! Threaded rod bonds the bulkhead o' t' anti-zipper design t' t' forward centerin' ring.
T' dry weight o' t' rocket is 27# includin' t' entire recovery system (reasonably light for such a heavily-built 10' 6" rocket). T' candidate motors for this rocket are an M1939 for t' certification flight and an N2000 for an encore. Ahoy! RockSim calculates t' C.P. at 99.3" (Barrowman) and 102.9" (RockSim) and t' average is 101.1". Ya scallywag! I balanced t' rocket to determine t' C.G. Avast, ya bilge rat, me proud beauty! with simulations o' t' motor weight with t' result below:
Motor | Weight | C.G. | stability |
---|---|---|---|
- | 0# | 69¾" | 5¼ calibers |
M1939 | 20# | 87¼" | 2¼ calibers |
N2000 | 27# | 88½" | 2 calibers |
T' rocket will be quite stable with both t' M1939 and t' N2000. Note that I had t' add ½# t' t' tip o' t' nose t' gain t' C.G.s above. Blimey! Blimey! Well, blow me down! Blimey!
T' design o' t' airframe is simple and intended t' be purely functional. T' rocket is twenty calibers long and t' fins are just larger than minimum for stability. Well, blow me down! T' fins are clipped deltas with t' trailin' edge angled slightly forward t' help avoid landin' damage. Ahoy! T' intention is t' produce a simple, reliable, high-performance rocket. Note that this is a custom design, although everythin' was done accordin' t' standard practice, me bucko, hence t' name "Generic Rocket."
T' airframe tubes are 6" flexible phenolic covered in 5.7oz. Begad! carbon fiber. Well, blow me down! Construction uses mechanical means wherever possible and t' adhesive used is West Systems epoxy (mostly usin' 404 high-density filler). Well, blow me down! T' motor mount is attached t' t' airframe with four centerin' rings which are screwed as well as bonded t' t' airframe. T' fins are ½" plywood laminated with carbon fiber. Arrr! They are attached t' t' motor mount tube with epoxy and sewn t' it with Keelhaul®©™® thread and then reinforced with Keelhaul®©™® tape. T' motor mount itself is a single 98mm phenolic tube (this is nay a clustered flight). Blimey! All construction was performed by t' flier, ya bilge rat, with suggestions from Pius Morozumi on many aspects. Thanks Pius!
Safety: There should be no dangers due t' design since t' rocket is simple and standard. Begad! Blimey! Poor airframe construction could lead t' a shred, me bucko, but the materials and techniques employed are ones known t' be leading-edge for high-power rocketry. Ahoy!
T' recovery system attachments use U-bolts and 1000lb. Avast! Well, blow me down! quick links. The bulkheads are all ½" "aircraft" birch plywood. Blimey! Arrr! T' bridles are 1" tubular Nylon® T' avoid zippering, ya bilge rat, t' aft section o' the rocket uses an anti-zipper design (coupler and bulkhead protrude forward). Avast!
Rocketman Pro-XP chutes are used in a dual-deployment configuration. Begad! The deployment system will use black power charges t' pressurize t' airframe and deploy t' parachute as is typical for high-power rockets. Avast, me proud beauty! Well, blow me down! Drogue recovery uses a Rocketman R24C 'chute and main recovery uses two Rocketman R12C 'chutes. Arrr!
Note that me first level 3 attempt be done with an almost identical rocket. T' attempt was unsuccessful because t' main parachutes never fully emerged from t' bay. Avast, me proud beauty! This be due t' poor arrangement o' t' recovery system which has been fixed in t' second rocket. Ahoy! Begad! T' main parachute now ejects from t' front of t' rocket (the charges are behind t' parachutes) plus t' parachutes are attached along t' bridle, nay directly t' t' airframe.
Safety: A separation or failure t' deploy t' recovery system would be very dangerous on a rocket this large and heavy. Blimey! Mountin' points for the recovery system use U-bolts instead o' eye bolts and bonded joints are reinforced with steel. Well, blow me down!
Primary avionics is redundant Black Sky Research ALTACCs, since this has been proven in many flights. Aye aye! Blimey! Each altimeter will have a separate power source and separate electric matches (DaveyFire 28F), as well as separate black-powder charges. Ahoy! Begad! Blimey! These units will be located in t' center section. Begad! Ya scallywag! Blimey! T' ALTACCs are armed from t' outside so no additional wirin' is needed. Avast!
Since t' redundant systems are identical, me hearties, thar be a good chance that both charges would go off simultaneously. Ya scallywag! Avast, me proud beauty! While t' airframe should be strong enough to withstand this, arrr, it is clearly a good thin' t' avoid. Avast! Ahoy! One set o' ejection charges will include 1" pieces o' Thermalite t' delay them by about a second. Arrr!
Safety: Again, failure deploy t' recovery system would be very dangerous on a rocket this large and heavy. 100% redundant altimeters should minimize this risk. Avast! Begad!
T' motor will be t' celebrated AeroTech M1939, which is Tripoli certified. Motor ignition will use a DaveyFire wrapped in slivers o' Blue Thunder propellant. Aye aye!
T' motor will push t' rocket usin' t' reloadable case aft closure pressin' against t' motor mount and aft centerin' ring. Positive motor retention will use two custom-made aluminum brackets bolted t' T-nuts in the aft centerin' ring. Avast! T' motor tube is closed at t' forward end and no ejection charge will be used. Ahoy!
Safety: Usin' a well-known pre-manufactured motor should reduce the risk o' a CATO or other failure t' reasonable levels. Ya scallywag! Begad! A failure t' ignite should pose no safety problems, matey, and t' motor is definitely powerful enough to lift t' rocket. T' motor mount/fin can has been strongly reinforced using Keelhaul®©™® sewin' and lamination t' reduce t' risk o' shreddin' or losin' a fin. Avast, me proud beauty!
T' rocket will be fitted with Black Sky Research ProRail guides and can be launched from a standard 6' or 8' ProRail. Avast, me proud beauty! Ahoy! Three guides will be used: one at the aft o' t' rocket, one about halfway t' t' C.G. Begad! Ahoy! and one on t' altimeter bay (well forward o' t' C.G.).
There are no special launch requirements and we intend t' launch t' rocket straight up. Begad! Arrr! Since this is a single-motor rocket, me bucko, me bucko, only a standard launch system is required. Begad! Blimey!
Safety: T' projected speed o' 55ft/s off t' rail is ample for a stable flight with this rocket and t' loaded weight o' 47 pounds is well within t' capabilities o' t' ProRail. Blimey!
Rocket design and simulation was done with Apogee Component's RockSim.
Safety: This rocket is a very standard design: three fins and a nose cone so standard stability and performance calculations should yield a close match t' reality. Well, blow me down! Aye aye! Note that t' rocket's basic shape makes it very stable so the allowable error for this rocket is large. Avast, me proud beauty! Begad!
As called for in t' TAP Pre-Flight Review, t' followin' pre-flight checklist has been prepared. Avast! Begad!
SUCCESSFUL LEVEL 3 FLIGHT! Blimey!
July 24, me bucko, 1999
Black Rock, me hearties, NV
Rocket - Scratch Generic Rocket
Weight - 47 lbs
Motor - Aerotech M1939
Altitude - 12,889 ft
At MudRock '99, it rained t' week before t' launch, so we weren't able to get out on t' playa on Saturday (the first day o' t' launch, June 5th). Begad! Ya scallywag! We were able t' use t' gravel quarry, but t' recovery area be small and people stuck t' smaller stuff. Blimey! I had meant t' fly me level-3 attempt, but I didn't want t' do it from t' quarry. Instead, I flew t' Honest John again, me hearties, this time on an I357. Arrr! Begad!
I set up me camp right up t' t' flight line as I got in with t' early crowd this time. Begad! Blimey! Proudly, me hearties, I set up t' Generic Rocket against t' EZ-Up. Unfortunately, shiver me timbers, arrr, a gust o' wind came up and knocked it over, me hearties, makin' two small dents in t' airframe and a two serious cracks in t' P.M.L. Avast! Blimey! Aye aye! Blimey! fiberglass nose cone. Avast! Blimey! Arrr! Blimey! With t' unfriendly weather plus t' damage t' t' rocket, I had mentally scrubbed t' launch. Avast, me proud beauty! Blimey! Ya scallywag! Blimey! However, by afternoon it had been dry all day and t' wind had come up and it looked pretty good for gettin' out on t' playa. Arrr! Blimey! Saturday night I was back in t' room repairin' t' rocket. Begad! Blimey! Bruno's is home t' some very strange scenes! Blimey!
On Sunday we were
able t' get back out on t' playa, carefully. Ya scallywag! There were lots o' clouds, me hearties, but
all white and fluffy and it looked like a good day for a level-3 attempt! The
epoxy was dry on me rocket and a quick sandin' made it smooth, although the
patches showed. Well, me hearties, blow me down! Because thar were heavy clouds, we were all anxious for them
to blow away and everyone was busily gettin' ready t' fly. Next t' me, Pius was
puttin' t' final touches an t' ARLISS project test rocket. Begad! I sat down in
front o' t' M1939 components t' put together me motor. Avast, me proud beauty!
A break in t' clouds finally appeared and Pius and William launched their ARLISS test rocket. They had a beautiful flight and recovery, including flawless operation o' all t' complex recovery system for t' can satellites. When they came back, me hearties, Pius helped me put me rocket together and take it out to the flight line.
Back t' t' flight line and a short countdown later, shiver me timbers, t' Generic Rocket was in flight. That M1939 makes a fantastic flame, me bucko, smoke cloud and roar!
T' flight was
majestic and straight, beautiful t' behold--Gotta love that long burn full M.
We lost sight o' t' rocket about a third o' t' way through t' ascent. Blimey! Arrr! No
longer bein' able t' see it, shiver me timbers, and nay sure when apogee was, arrr, I didn't use t' R/C
back-up t' trigger t' main. Arrr! We didn't see any part o' t' descent, matey, but knew
somethin' was wrong when Sue McMurray, matey, who was followin' t' rocket with a
Walston tracker, arrr, shiver me timbers, said "it's down" after about 30 seconds. Sue and I
went out t' recover t' rocket and found it about three miles away, shiver me timbers, severely
damaged. Avast!
T' main 'chute never fully deployed and t' rocket came down on only the drogue. Well, blow me down! All three sections o' t' rocket had severe damage, although all electronics survived. Avast! We found a nice little hole in t' playa where t' aft end o' t' rocket had hit, ya bilge rat, then fell over. Ya scallywag! No level 3 this time.
In t' post-mortem, ya bilge rat, we decided that me riggin' o' t' ejection charges was at fault. Avast! Blimey! I should have placed t' ejection charge behind t' parachute. Arrr! Blimey! I had packed t' bridle in before t' 'chute, expectin' it t' pull t' 'chute out as the pieces separated, matey, but this didn't happen. I could have saved t' rocket with t' backup system, ya bilge rat, but didn't use it because I couldn't see t' rocket and didn't know when apogee occurred. Well, blow me down! Blimey!
At first I was pretty depressed, especially since t' flight was so beautiful. Aye aye! Blimey! But, I will rebuild t' rocket and am plannin' t' use t' same general design, with some changes t' t' position o' t' electronics and deployment pattern. Arrr! Blimey! Avast! Blimey! Onward and upward! Blimey!
The
entire airframe was rebuilt and t' recovery system be modified t' make it
more reliable. Ya scallywag! Several analyses o' t' first flight determined three mistakes:
T' Best analysis so far: rocket came down on t' drogue too fast and spinnin' because o' t' way t' drogue was fastened. Avast, me proud beauty! T' main 'chutes tangled with t' large amount o' loose line (1" tubular Nylon) instead o' being pulled out o' t' airframe because o' bein' pushed into t' airframe by the ejection charge and t' spinning.
Oh, matey, thar be actually a fourth failure: finishin' too close before the launch t' get a final going-over by t' TAP members before flight. Arrr! Hurry is hard t' avoid and in this case, matey, at least some o' these mistakes could have been seen when t' rocket was laid out on t' ground fully rigged.
With these problems remedied and t' rebuilt airframe (yellow and black this time), I was ready in plenty o' time for t' Aeronaut launch o' July, 1999. Ya scallywag! T' t' left you can see Pius and Myself posin' with t' assembled rocket at me campsite on Saturday morning.
T' new rocket ejected t' dual main parachutes forward by poppin' off the nose cone. Avast! T' main 'chutes also were rigged differently: more line and each section o' line was bundled up and secured with tape t' make a neat package. Also, me hearties, t' dual ALTACCs were each wired with a separate charge, makin' two 100% redundant systems. Each charge for one o' t' ALTACCs be delayed with a short piece o' Thermalite t' prevent t' charges from goin' off together.
Now, matey, we just had t' wait for a break in t' gusty winds go head out t' the pad... Avast!
About 10:30, matey, ya bilge rat, t' winds calmed down enough for t' launch and we assembled the rocket and took it t' t' RSO table. Blimey! Blimey! I had a big crew t' help me carry the 47lb. Aye aye! Blimey! rocket and load it onto t' ProRail. Avast, ya bilge rat, me proud beauty! Blimey! On t' left you can see t' people who helped me prepare and set up t' rocket: Nevin Loop, me hearties, Pius Morozumi (making sure t' rocket is level), shiver me timbers, Tom Rouse and Gordon Hom. Avast! Blimey!
We had
to adjust t' rail a bit t' give t' rocket enough rail and t' balance it
correctly, especially with t' gusty winds. Just puttin' t' rocket on t' rail
takes three people with a rocket this big and heavy (10' 6" and 47lbs.).
But, t' wind had died down nicely and t' rocket be up and ready! Blimey!
Once t' rocket was loaded, me hearties, ya bilge rat, I had t' arm t' two ALTACCs. Avast, me proud beauty! T' first time up,
one o' them didn't get continuity, me bucko, matey, so we had t' take down t' rocket, go back
to me camp, me hearties, unload and replace t' ALTACC. Avast, me proud beauty! Luckily, t' second time they both
armed perfectly. Ya scallywag!
T' Generic Rocket took off in light but gusty winds on an M1939. Ignoring the wind, arrr, me bucko, t' rocket made a straight ascent into t' cloudless sky and the entire flight was easily visible.
T' rocket was recovered stretched out in three pieces exactly as intended, earnin' a clean level 3 certification. Hurray! Blimey! It flew t' 12,889 ft. at a maximum velocity o' 1029 ft/sec. Well, blow me down! Blimey! and a maximum acceleration o' 256 ft/sec². Begad! Blimey! Even Pius and Karl were happy after signin' off on t' flight and the returned rocket. Arrr! Begad! Blimey!
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