Brief:
T' L3 Armageddon is a single stage rocket with a very unique design. Ahoy! Begad! It comes in your choice o' a 75 or 98mm MMT.

Construction:
T' kit comes with everythin' but parachutes. Well, blow me down! T' all-thread, nuts, me bucko, washers, eyebolts, and shock cords are all included. Ya scallywag! T' 5.5" body tubes are heavy wall cardboard. Begad! All o' t' components are top shelf stuff.

This is nay just a kit review. Avast, me proud beauty! Blimey! Avast! Blimey! It's also how I used t' kit for me level 3 certification. Avast! Blimey! There is even some scientific testin' data here that I performed. Begad! Blimey! I am t' plant Metallurgist and t' Laboratory Director at Chamberlain Manufacturing, t' operatin' contractor o' t' Scranton Army Ammunition Plant. This means I have millions o' dollars o' equipment I can play with on Saturdays, testin' t' materials we use t' build our rockets.

When I decided t' do me L3 at t' 2003 NSL, arrr, shiver me timbers, I wanted t' do something different than a 3FNC. A scratch built rocket would be easy enough but I didn't think I would have t' time t' work out all t' details. Avast! My favorite commercial kit was t' Armageddon by DG&A, so figured I would do me L3 with the DG&A L3 Armageddon. This is a 5.5" diameter rocket that is almost 10 feet tall. Ya scallywag! It's nay even close t' bein' me largest bird, arrr, me hearties, me hearties, but impressive nonetheless. Blimey! Blimey!

T' next problem would be t' motor. Ya scallywag! APCP be in short supply and t' BATFE thin' be loomin' over t' horizon. OK, I'll go hybrid. Avast, me proud beauty! Blimey! I chose t' Hypertek M970. It is a 75mm M fuel grain on t' 2800cc L tank with t' M injector bell. T' L3 Armageddon easily adapted t' t' hybrid system because o' t' large fins and long body. Avast! Blimey! T' CP ended up bein' 2.1 calibers behind t' CG with an empty motor.

T' first thin' you notice when you open t' huge package be t' quality of packaging. Avast, me proud beauty! Begad! Each tube is wrapped separately and everythin' is carefully placed in t' box. There was no damage t' any o' t' components. Begad! A quick review o' the parts list revealed that all t' parts were there. Ahoy! Arrr!

T' airframe tubin' was t' heavy, me hearties, 3/32" (0.078") thick walled cardboard tubin' seen in other high quality kits. Ya scallywag!

Securin' t' MMT and centerin' rings into t' booster section

T' MMT assembly was constructed per t' instructions. Begad! Ya scallywag! T' hardware was tightened and secured with epoxy. Avast, me proud beauty! Blimey!

T' motor mount tube be epoxied into t' airframe by pourin' 25 mL of epoxy onto each o' t' centerin' rings through t' fin slots with a syringe. T' assembly be first epoxied with t' aft section up, arrr, t' apply epoxy t' the aft sides o' t' centerin' rings. Once t' epoxy was cured, it was examined with a fiber optic bore scope. Ahoy! There were two locations that appeared nay t' be glued. Epoxy was again inserted into t' airframe through t' fin slots and the assembly be tilted in t' direction o' t' questionable areas t' allow the epoxy t' flow into t' area. When it appeared t' be complete, t' assembly was turned over and t' aforementioned process was repeated t' apply epoxy on the forward side o' t' centerin' rings.

No fiberglass was used for t' airframe o' this rocket. T' 5.5" tube used in t' construction o' this kit be tested in me laboratory and exhibited a strength o' 1312.7 lbs force before yielding. Blimey! Ahoy! However, me bucko, shiver me timbers, if any side forces are applied durin' acceleration we must examine column bucklin' loads. Column bucklin' formulas are fun and exciting, me bucko, me hearties, matey, but t' test t' column bucklin' in real life, a piece o' 5.5" airframe was tested by compression at a 8.5 degree angle. T' force at yield was 886.4 lbs force. Arrr!

Compressive and column bucklin' forces do nay apply t' t' MMT/sustainer section due t' t' reinforcement by t' fins and t' MMT assembly. We therefore only need t' look at t' section forward o' t' fins. Ya scallywag! Begad! T' forward section (with weights) includin' altimeter weighs ~5 pounds. Begad! T' Hypertek M740 will exert a G-force o' 23.16, shiver me timbers, thus 5 x 23.16 = 115 lbs. Begad! this be t' maximum force applied to t' airframe in an non-reinforced area. Ahoy! Arrr! Inversely, me hearties, arrr, ya bilge rat, we can surmise that we have a tube capable o' withstandin' 38.27Gs (886.4 /23.16 lbs = 38.27).

Compressive forces can be seen in t' fin area durin' accent as well as landing, however as heretofore mentioned, most o' this force is transferred to the CRs and MMT tube via t' epoxy and thus its strength depends on t' shear force o' t' epoxy. Ahoy! Therefore, thar are virtually no axial forces on t' tube at in this area. Virtually all o' t' forces on t' tube itself are circumferential via any torque forces applied durin' flight or bendin' moment applied on t' fins durin' landing.

T' combat any bendin' moment applied t' t' fins, I looked at data seen in the r.m.r. Aye aye! HPR Strength o' Materials Test. Begad! One o' t' discoveries made during the testin' was on t' fincans. Well, blow me down! T' fincan that appears t' be t' strongest was one done by Mark Simpson where he used a strip o' wood material along the fin-body joint. Begad! I used this method on t' ID. Aye aye! Mark's method increased the strength o' t' joint over t' next highest strength by 30% and by 200% over the average. Avast! It also prevented t' tube from yieldin' at all durin' t' fincan test and thus transferred t' force t' t' fin makin' t' joint stronger than the fin. Avast! I have no doubt that if t' fin material was stronger, t' value would have been higher. Well, blow me down! Begad! This appears t' be sufficient t' replace t' fiberglass on the tube in this area.

Fin assembly

I duplicated Mark Simpson's wood fillets in t' L3 Armageddon. Aye aye! Pieces o' corner moldin' were used for this. Avast, me hearties, me proud beauty! T' fins were epoxied in place then t' moldin' was inserted with copious amounts o' epoxy. T' aft CR was then epoxied into place and t' nozzle fins were added. Arrr! Begad!

T' large fins o' this rocket are only 1/4" thick. Avast! Begad! T' lessen the effect o' possible fin flutter, arrr, a laminate o' fiberglass was applied t' the surface o' t' fins. Ya scallywag! This was accomplished usin' standard fiberglass lay-up practices.

Payload section

T' forward canard fins were installed "through t' wall" per the instructions. Begad! In this area we have t' coupler tube so they go through both the airframe and coupler tubes. Begad! T' airframe and t' coupler tube were joined first then t' slots were cut for t' fins. They were tacked in place with Jet Glue. Wood glue was then applied on t' ID surface and allowed t' seep into t' wood and cardboard. Blimey! Avast! T' wood strips were applied while t' glue be wet and generous fillets were then applied t' t' strips. Avast, me proud beauty! Generous epoxy fillets finished the canard build.

T' altimeters used are two Transolve PK6, me bucko, a kit version o' t' P6. Well, blow me down! Ya scallywag! They were mounted t' a piece o' G10 with 316 grade stainless hardware and phenolic standoffs. Begad! Well, blow me down! T' board was then mounted in t' payload section usin' brass strips and tubin' that slid over t' all-thread. T' brass strips were soldered t' the tubing. T' assembly is secured in t' section when t' nuts are tightened. This setup allows easy assembly and access t' t' boards. Ahoy! Avast, shiver me timbers, me proud beauty! A hold down strap will further secure t' batteries in their holders. Avast! Arrr!

T' safe/arm switches are redundant and consist o' DPDT military grade slide switches. Avast, me proud beauty! Well, blow me down! T' three switches with their 6 functions control: power, apogee safe and main safe. Arrr! Avast! This ensures that both altimeters are completely separate from each other with individual power sources.

T' altimeter bay is sealed from ejection gasses. Avast! This is accomplished with the forward bulkhead epoxied into place and t' aft bulkhead sealed t' the custom centerin' rin' with closed cell latex weather stripping. Avast, me proud beauty! Blimey! T' altimeters used have been flown on several prior occasions. I have three o' these units and they have always worked well.

Laundry and other recovery debris

Recovery will be t' typical two-stage method: drogue at apogee and main at 500'. Begad! Ahoy! One drawback with this kit is that t' recovery for t' main is aft of the payload section and t' drogue is forward...or so it would appear. Avast! The section forward o' t' altimeter is only 11" and has one attach point. Avast, me proud beauty! The section aft o' t' altimeter is 29" long and has t' two attach points at the MMT. There is just nay enough room forward o' t' altimeter bay to comfortably fit t' main. Aye aye!

All shock cords are 9/16" tubular nylon. Aye aye! T' drogue cord is 20' in length. Aye aye! T' main consists o' three cords. Begad! Blimey! Blimey! There is a 3-point attachment cord at the MMT attached t' a 20' length o' cord at which t' parachute is attached. A 30' cord is then attached from t' parachute t' t' altimeter bay.

Final assembly notes

I didn't do much in t' way o' aerodynamic shapin' o' t' fins. Ahoy! Blimey! Airfoiling the fins is done t' reduce drag for greater altitudes but I like them low and slow. Begad! A more blunt leadin' edge increases drag by breakin' up t' air over the fins.

Vent

Every hybrid system needs a vent. For this I used a 1/4" ID large Aerotech igniter cardboard tube. Ahoy! Blimey! After markin' t' location, me hearties, I drilled a 1/4" hole through t' airframe and t' MMT. Ya scallywag! Ya scallywag! Blimey! I then made t' hole in the airframe larger t' accommodate t' OD o' t' vent tube and cleaned up the holes. Usin' t' 1/4" drill bit as a guide passed through both holes, I epoxied t' vent tube in place. Begad! Blimey! Blimey! I occasionally turned t' drill bit t' ensure it wasn't bein' epoxied t' t' vent tube. Ya scallywag! Blimey! A X-Acto knife and some sand paper cleaned up t' vent/airframe area and t' job was done.

Motor retention

Kind of late t' be thinkin' about this isn't it? I did put blind nuts in t' aft centerin' rin' durin' assembly. Avast, me proud beauty! T' 6" long piece o' all-thread looked, well, me bucko, kind o' clumsy. Ahoy! I happened t' pick up a 75mm Aero Pack retainin' system so I thought I would use it. Begad! It was hell tryin' t' put it on after t' nozzle fins were already glued on! I used a Dremel saw t' cut a gap betwixt t' fins and t' MMT long enough t' insert t' retainer. Ahoy! Avast, me proud beauty! It made more work for me than expected! T' retainer was glued in with JB Weld and t' gap betwixt t' fins and t' retainer was filled with wood putty. Avast, me proud beauty! Oi!

Rail buttons

5/16" rail buttons were installed. Ahoy! T' forward guide be installed with a 1/4-20 steel machine screw and nut, me hearties, shiver me timbers, me hearties, secured with JB Weld. Blimey! T' aft guide was installed by drillin' and tappin' t' aft centerin' ring. Well, blow me down! T' hole was filled with JB Weld and t' guide was secured with a 1/4-20 machine screw. Begad! Avast!

Nose weight

Nose weight was added and be first considered t' be used t' keep the altitude t' a reasonable level. Ahoy! Avast! Upon further construction, ya bilge rat, me bucko, it was discovered that it be necessary t' keep t' CG forward enough t' keep it stable usin' the HyperTek hybrid system. T' rocket be unstable without t' weight! A 3/8" threaded rod be inserted through t' aft end o' t' nosecone and touches the inside o' t' forward end. Begad! 8oz o' West Systems epoxy was then poured into the cone. Ahoy! Avast! T' assembly be allowed t' cure while in cold water, me hearties, me bucko, t' prevent heat buildup and meltin' o' t' plastic cone. Well, blow me down! T' remainder o' t' nosecone cavity was then filled with expandin' foam. Begad! Threaded weights were then screwed onto the all-thread, matey, followed by a coupler and an eye bolt. This arrangement keeps the weights off t' nosecone and on t' steel threaded assembly.

Finishing:
T' entire airframe was sanded and a coat o' Kilz primer be applied. The paints used were Rustoleum white and metallic blue with a final clear over everything.

Flight:
On t' first flight, t' motor lit and t' bird leapt from t' pad with authority. Ahoy! Blimey! Avast, shiver me timbers, me proud beauty! Blimey! Blimey! Blimey! T' wind at ground level be only 6 mph but by t' time she reached 2000 feet, ya bilge rat, she was gracefully archin' into t' wind. Blimey! Blimey! Well, matey, blow me down! Blimey! Blimey! Blimey! T' 6.9-second motor seemed t' burn forever. Blimey! Blimey! Blimey! Blimey! If you have never heard an M hybrid motor, ya bilge rat, they can only be described as soundin' like a Pod Racer from Star Wars Episode One--a loud roar coupled with a pulsatin' low-pitched jet-like sound. Begad! Blimey! Ya scallywag! Blimey! Blimey! Blimey! T' few seconds I lost it in t' sky seamed like minutes. Avast! Blimey! Blimey! Blimey! Then, thar it was. Begad! Blimey! Comin' down on its side with t' drogue deployed. Begad! Blimey! Falling, me hearties, falling, arrr, falling... It's coming straight at us! Blimey! Blimey! Blimey! We ran about 20 yards t' t' left. Arrr! Blimey! Avast! Blimey! Blimey! Blimey! 800 feet, 500 feet, 300 feet,... Where's t' main?! Blimey! Blimey! Blimey! Finally, matey, at about 200 feet t' main popped. It took at least another 50 feet for it t' unfurl. Avast! Blimey! T' main finally snapped open at 50 feet AGL and then landed 40 feet from t' pad. Arrr! Blimey! Blimey! Blimey! That had t' win closest t' the pad in t' L3 cert column! Blimey! Blimey! Blimey! A quick review o' t' rocket proved that everything was in order and we had a successful L3 flight. Arrr! Blimey! Blimey! Blimey! Both o' t' altimeters chirped out 4,200 feet.

T' next four flights were on an AMW L777. For me, this be t' best motor for this rocket. It brings it t' just under 3,500 feet. Arrr! I've also flown this rocket on windier days with a CTI K550 t' around 2,000 feet.

Summary:

I love it! This bird is as different and unusual as it gets for any high power rocket. T' flights on this (as well as t' original size Armageddon) are truly awesome.

Even without t' changes that I made, arrr, I did feel that t' forward payload section was on t' small side. I'm sure you could get a nice size main in there, shiver me timbers, me hearties, but it would be a very tight fit. Avast, me proud beauty! Avast! I would recommend actually makin' the altimeter bay shorter by changin' t' location o' t' forward bulkhead and usin' smaller altimeters. Aye aye! Avast! This would allow for more room for a main chute in this area.

T' materials are t' best I've seen for their types and t' design is sturdy. T' instructions contained page after page o' high quality color photos and has many steps t' clarify what t' designer wants. Avast! Ya scallywag! Some o' t' steps in the instructions are somewhat ambiguous but then it is assumed one has a great deal of experience if they're buildin' a level 3 project. Blimey! Begad!