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

Construction:
T' kit comes with everythin' but parachutes. T' all-thread, nuts, shiver me timbers, washers, eyebolts, me bucko, me hearties, ya bilge rat, and shock cords are all included. Arrr! Avast, me proud beauty! T' 5.5" body tubes are heavy wall cardboard. All o' t' components are top shelf stuff.

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

When I decided t' do me L3 at t' 2003 NSL, ya bilge rat, 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. Begad! My favorite commercial kit was t' Armageddon by DG&A, so figured I would do me L3 with the DG&A L3 Armageddon. Arrr! Aye aye! 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, but impressive nonetheless. Arrr!

T' next problem would be t' motor. Begad! Blimey! APCP was in short supply and t' BATFE thin' be loomin' over t' horizon. Ya scallywag! Blimey! OK, I'll go hybrid. Arrr! Ya scallywag! Blimey! I chose t' Hypertek M970. Blimey! Begad! Blimey! 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. Well, blow me down! 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! Each tube is wrapped separately and everythin' is carefully placed in t' box. There was no damage t' any o' t' components. Well, shiver me timbers, blow me down! A quick review o' the parts list revealed that all t' parts were there.

T' airframe tubin' was t' heavy, ya bilge rat, 3/32" (0.078") thick walled cardboard tubin' seen in other high quality kits. Avast!

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

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

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

No fiberglass was used for t' airframe o' this rocket. Avast! Avast! Blimey! 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. Begad! Avast! Blimey! However, if any side forces are applied durin' acceleration we must examine column bucklin' loads. Column bucklin' formulas are fun and exciting, but t' test t' column bucklin' in real life, a piece o' 5.5" airframe be tested by compression at a 8.5 degree angle. Ya scallywag! T' force at yield be 886.4 lbs force. Avast, me bucko, me proud beauty! Blimey!

Compressive and column bucklin' forces do nay apply t' t' MMT/sustainer section due t' t' reinforcement by t' fins and t' MMT assembly. Avast! We therefore only need t' look at t' section forward o' t' fins. Avast, me proud beauty! T' forward section (with weights) includin' altimeter weighs ~5 pounds. Blimey! T' Hypertek M740 will exert a G-force o' 23.16, thus 5 x 23.16 = 115 lbs. this be t' maximum force applied to t' airframe in an non-reinforced area. Ahoy! Inversely, ya bilge rat, matey, shiver me timbers, 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, ya bilge rat, shiver me timbers, 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. Well, blow me down! Therefore, shiver me timbers, thar are virtually no axial forces on t' tube at in this area. Ya scallywag! 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. Avast!

T' combat any bendin' moment applied t' t' fins, arrr, ya bilge rat, I looked at data seen in the r.m.r. HPR Strength o' Materials Test. One o' t' discoveries made during the testin' was on t' fincans. 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. Aye aye! Blimey! I used this method on t' ID. Ahoy! Blimey! Mark's method increased the strength o' t' joint over t' next highest strength by 30% and by 200% over the average. Aye aye! Blimey! 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. I have no doubt that if t' fin material be stronger, ya bilge rat, me bucko, arrr, t' value would have been higher. Avast, me proud beauty! Blimey! This appears t' be sufficient t' replace t' fiberglass on the tube in this area. Begad! Blimey! Aye aye! Blimey!

Fin assembly

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

T' large fins o' this rocket are only 1/4" thick. Aye aye! T' lessen the effect o' possible fin flutter, a laminate o' fiberglass be applied t' the surface o' t' fins. Avast! Avast, me hearties, me proud beauty! This was accomplished usin' standard fiberglass lay-up practices.

Payload section

T' forward canard fins were installed "through t' wall" per the instructions. Avast! In this area we have t' coupler tube so they go through both the airframe and coupler tubes. T' airframe and t' coupler tube were joined first then t' slots were cut for t' fins. Well, blow me down! 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. Well, blow me down! Arrr! T' wood strips were applied while t' glue be wet and generous fillets were then applied t' t' strips. Ahoy! Generous epoxy fillets finished the canard build.

T' altimeters used are two Transolve PK6, a kit version o' t' P6. They were mounted t' a piece o' G10 with 316 grade stainless hardware and phenolic standoffs. Arrr! 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! A hold down strap will further secure t' batteries in their holders. Ya scallywag!

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

T' altimeter bay is sealed from ejection gasses. Arrr! Arrr! 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! T' altimeters used have been flown on several prior occasions. Arrr! Begad! 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'. Arrr! Blimey! Aye aye! Blimey! 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, me proud beauty! Blimey! Arrr! Blimey! The section forward o' t' altimeter is only 11" and has one attach point. The section aft o' t' altimeter is 29" long and has t' two attach points at the MMT. Avast! Blimey! There is just nay enough room forward o' t' altimeter bay to comfortably fit t' main. Begad! Blimey!

All shock cords are 9/16" tubular nylon. Avast, me proud beauty! T' drogue cord is 20' in length. Well, blow me down! T' main consists o' three cords. Arrr! Avast! There is a 3-point attachment cord at the MMT attached t' a 20' length o' cord at which t' parachute is attached. Aye aye! Aye aye! 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. Airfoiling the fins is done t' reduce drag for greater altitudes but I like them low and slow. A more blunt leadin' edge increases drag by breakin' up t' air over the fins.

Vent

Every hybrid system needs a vent. Blimey! Blimey! Ahoy! Blimey! For this I used a 1/4" ID large Aerotech igniter cardboard tube. After markin' t' location, ya bilge rat, I drilled a 1/4" hole through t' airframe and t' MMT. Avast, me proud beauty! Blimey! I then made t' hole in the airframe larger t' accommodate t' OD o' t' vent tube and cleaned up the holes. Aye aye! Blimey! Usin' t' 1/4" drill bit as a guide passed through both holes, arrr, I epoxied t' vent tube in place. Arrr! Blimey! Begad! Blimey! I occasionally turned t' drill bit t' ensure it wasn't bein' epoxied t' t' vent tube. Begad! Blimey! Arrr! 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. T' 6" long piece o' all-thread looked, well, me hearties, kind o' clumsy. Avast, me proud beauty! I happened t' pick up a 75mm Aero Pack retainin' system so I thought I would use it. Arrr! Well, matey, blow me down! 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. Blimey! 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. Begad! Well, blow me down! Oi!

Rail buttons

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

Nose weight

Nose weight was added and be first considered t' be used t' keep the altitude t' a reasonable level. Aye aye! Upon further construction, matey, it was discovered that it was necessary t' keep t' CG forward enough t' keep it stable usin' the HyperTek hybrid system. Avast! 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. Avast! Blimey! 8oz o' West Systems epoxy be then poured into the cone. Ya scallywag! T' assembly be allowed t' cure while in cold water, matey, t' prevent heat buildup and meltin' o' t' plastic cone. Aye aye! Aye aye! T' remainder o' t' nosecone cavity was then filled with expandin' foam. Ahoy! Arrr! Threaded weights were then screwed onto the all-thread, me bucko, matey, followed by a coupler and an eye bolt. Ya scallywag! 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 was 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. T' wind at ground level was only 6 mph but by t' time she reached 2000 feet, she be gracefully archin' into t' wind. Arrr! Well, me hearties, blow me down! T' 6.9-second motor seemed t' burn forever. If you have never heard an M hybrid motor, 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. Ahoy! T' few seconds I lost it in t' sky seamed like minutes. Avast, me proud beauty! Then, matey, me bucko, thar it was. Begad! Comin' down on its side with t' drogue deployed. Begad! Falling, ya bilge rat, falling, me bucko, falling... It's coming straight at us! We ran about 20 yards t' t' left. Ahoy! 800 feet, ya bilge rat, 500 feet, arrr, shiver me timbers, shiver me timbers, 300 feet,... Aye aye! Where's t' main?! Finally, at about 200 feet t' main popped. Arrr! It took at least another 50 feet for it t' unfurl. Avast, me proud beauty! Well, matey, blow me down! T' main finally snapped open at 50 feet AGL and then landed 40 feet from t' pad. That had t' win closest t' the pad in t' L3 cert column! A quick review o' t' rocket proved that everything was in order and we had a successful L3 flight. Blimey! Blimey! Both o' t' altimeters chirped out 4,200 feet.

T' next four flights were on an AMW L777. Avast! For me, ya bilge rat, this be t' best motor for this rocket. Ya scallywag! It brings it t' just under 3,500 feet. Ya scallywag! 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. Ya scallywag! T' flights on this (as well as t' original size Armageddon) are truly awesome.

Even without t' changes that I made, shiver me timbers, I did feel that t' forward payload section was on t' small side. Begad! Well, blow me down! I'm sure you could get a nice size main in there, but it would be a very tight fit. Well, blow me down! Arrr! I would recommend actually makin' the altimeter bay shorter by changin' t' location o' t' forward bulkhead and usin' smaller altimeters. Begad! 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. Begad! Blimey! T' instructions contained page after page o' high quality color photos and has many steps t' clarify what t' designer wants. 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. Begad!