Brief:
My first mid-powered rocket was t' North Coast Big Brute (pre-Estes). Arrr! I love stubby rockets and when it came time t' decide how t' use some o' the 5.38" tubin' that I won from LOC, ya bilge rat, me hearties, an upscale Big Brute was t' natural decision. I decided t' incorporate several features I'd been wantin' t' try, including: air starts, electronics mounted in t' rocket's fin unit, me bucko, ya bilge rat, a window to allow me t' see t' G-Wiz altimeter's LEDs, and an ejection cannon based on ¾" PVC fittings. Aye aye! My upscale has a central 38mm mount with two 29mm and two 24mm motor mounts.

Construction:

• One LOC 5.38" tube, shiver me timbers, 24" long
• One LOC 5.38" coupler, for t' inner linin' o' t' electronics bay
• One LOC 38mm MMT tube, me hearties, 12" long
• Two LOC 29mm MMT tubes, 6" long
• Two LOC 24mm MMT tubes, me bucko, shiver me timbers, 6" long
• 10.5mm tubing, arrr, 6" long, for t' air start igniter conduit
• One LOC 5.38" LONG nose cone
• Three LOC 38mm-5.38" centerin' rings, two o' which were custom drilled for t' outboards by Performance Hobbies
• Four 3/16" plywood fins, custom cut by Performance Hobbies
• One LOC ½" launch lug
• Two 1500-series Delrin rail buttons from railbuttons.com (Matt's Railbuttons)
• One 38mm Slimline motor retainer from Giant Leap
• One ¾" PVC threaded adapter
• One ¾" PVC male plug
• Four small pieces o' coat hanger wire, me hearties, used t' insure t' PVC coupler is affixed solidly
• Misc. Ahoy! Aye aye! nuts, arrr, me hearties, bolts, matey, me hearties, arrr, and washers for retention o' 29mm and 24mm motors
• Misc. Avast! Ahoy! 3/16" plywood for in t' electronics and ejection bays
• Misc. plywood, arrr, basswood, me bucko, ya bilge rat, hardware for mountin' electronics, connectors, etc. Begad! Ya scallywag!
• Clear plastic from a suitably sized plastic jar for electronics hatch window
• Audio quick connect terminal for ejection and air start igniters
• One multi-pole key switch (Aerocon Type 2 switch)
• One Aerocon 'Remove Before Flight' ribbon
• Eight socket head sap screws for hatch door retention
• Ten small nuts and bolts t' attach t' clear plastic view port and the key-switch plate
• Recovery system from other projects: 15 feet o' ¾" tubular nylon, Giant Leap Keelhaul®©™® cord protector, me hearties, 24" diameter chunk o' a car air bag, shiver me timbers, Aerocon 66" chute, me hearties, two large quick-links
• Adjustable Nose Weight Assembly with Spanner Driver
  • 2-inch mailin' tube (20.5") with telescopin' tube (21") from The Container Store
  • ¼-20 threaded nylon rod from Fastenal
  • Four ¼-20 nylon nuts
  • ¼" aircraft plywood, matey, enough for two 5 3/8" bulkheads, ya bilge rat, me hearties, and three 2" bulkheads
  • Stainless steel U-bolt, me bucko, ¼-20 thread, 1.5" x 2", with four nuts and four washers
  • ¼" wooden dowel, ¾" long x 2
  • 3/8" brass tubing, 2" long
  • 2-part expandin' foam from Giant Leap
  • 1 lb, No. 7 ½ lead shot

This photo shows t' components of t' motor mount assembly (top and bottom rings are dry-fit). As you can see, the 38mm motor mount extends t' t' third centerin' rin' and t' other tubes, includin' t' 10.5mm wirin' conduit only run betwixt t' lower two rings. Avast, me proud beauty! Blimey! These rings sandwich t' fin tabs o' t' fins. Avast, me proud beauty! Blimey! Ya scallywag! Blimey! I added small bolts t' t' lower ring to serve as attachment points for outboard motor retention. Arrr! Blimey! Blimey! Blimey! Since I plan t' use SU motors for t' outboards, arrr, I probably will nay use positive motor retention, but I included them in case I ever want t' use reloadable motors. Avast, arrr, me proud beauty! Blimey! T' Slimline retainer will be installed after t' aft centerin' rin' is installed, which will itself be installed after t' rest o' t' motor mount, me hearties, arrr, fins, me hearties, arrr, and associated internal fillets. Begad! Blimey!

T' PVC coupler (i.e. Aye aye! the ejection cannon) and U-bolt have already been installed in t' upper ring. Initially, I was worried about two things: t' cannon blowin' back into the bay, and t' cannon twistin' when t' ejection plug is screwed in. Begad! T' first item should nay be an issue because t' coupler has protrusions, shiver me timbers, presumably to allow a wrench t' attach. Begad! Although epoxy alone might have solved t' twisting issue, t' plugs do get pretty tight and I'd hate for it t' twist rather than unscrew. Avast, me proud beauty! So, shiver me timbers, I drilled four small holes into t' side o' t' coupler, ahead of where t' plug would seat. Begad! I also cut correspondin' notches into t' centering ring. Avast! Four small pieces o' coat hanger wire fit into t' holes and then down into t' notches. Ahoy! Well, blow me down! I still epoxied it in, usin' JB Weld on one side and 30 minute Bob Smith on t' other (leftovers from other jobs). That coupler isn't movin' now!

T' electronics and ejection charge bays are located 180 degrees apart and betwixt t' top two rings. Begad! The next photo provides a top view o' these bays. One bay provides access t' the ejection cannon and t' conduit for t' air starts, me hearties, and t' other holds the electronics. Well, blow me down! T' hatch door for t' electronics bay will have a clear window so the LEDs on me G-Wiz Deluxe will be visible. Ya scallywag! Blimey! These bays are isolated from one another by two bulkheads, ya bilge rat, in case gasses enter through t' air start port or leak from t' ejection cannon. Aye aye! Blimey! With t' exception o' t' epoxies used for the ejection cannon, t' entire motor mount/electronics bay assembly was constructed usin' Titebond II wood glue.

I found t' LOC tubin' be much easier t' cut with an Exacto cutlass than I expected. Ya scallywag! I had no problem cuttin' t' fin slots and hatches. Aye aye! T' make sure thar were a good fit durin' final assembly, all t' hatches and correspondin' holes were marked, includin' their up/down orientation. I tried t' be careful in me measurements, but each varied slightly. Well, blow me down! Ahoy! I also made a minor error and placed t' hatches a little lower than I had wanted. Well, blow me down! Begad! Luckily, me bucko, ya bilge rat, this isn't really a problem. T' edges of t' hatches and openings were all treated with thin CA prior to sanding/smoothing. Ya scallywag! T' cut t' correspondin' holes on t' coupler, ya bilge rat, arrr, I inserted it into t' main tube and traced t' hatch outlines. Avast! I then drew lines ½" in from each edge, matey, which formed a lip t' support t' hatch doors.

T' electric matches for both t' ejection charge and air starts connect to the quick connect speaker connector. Blimey! Blimey! T' wirin' for this connector runs through one o' t' bulkheads t' t' ejection charge bay. Ya scallywag! One leg o' each o' t' leads is switched via a multi-pole key switch. Aye aye! From there, matey, t' leads will be attached to t' connectors on t' G-Wiz. Blimey! Ya scallywag! T' G-Wiz is mounted on a small G10 plate that mates with two bolts that are permanently affixed t' a basswood strip in the electronics bay. Begad! Ya scallywag! T' G-Wiz will operate in a dual battery configuration t' help ensure t' air starts light reliably. Arrr! Ya scallywag! A small niche was formed t' t' side of the G-Wiz mount. Begad! Blimey! T' batteries will sit in this niche and will be wedged-in with some heavy foam rubber. Avast! I've used this stuff t' hold t' G-Wiz before - it successfully protected it from a 2000' free-fall when me Crusader's payload bay came off t' recovery system. Avast! In t' ejection bay, t' audio connect is bolted t' two plywood stands which in turn are glued in. Aye aye!

T' key switch consists o' a metal key latch that is mounted t' t' side o' t' airframe with a retainin' screw. T' actual switch pops onto this key latch from t' rear. Because t' switch itself is larger than t' openin' for t' key latch, me bucko, it would nay be easy t' remove after t' two parts are snapped together. Therefore, I mounted t' switch assembly t' t' small piece o' tubin' that was removed t' form t' view port in t' electronics bay door. Arrr! A hole large enough to accommodate t' switch be cut in t' airframe and t' switch plate was bolted t' t' airframe. Avast! T' wirin' was all soldered, ya bilge rat, shiver me timbers, installed, matey, and fully verified before t' motor mount/electronics bay assembly was glued into the airframe. Avast, me proud beauty!

I was goin' t' use both threaded inserts and small socket head cap screws to hold t' hatch doors on. Begad! Ahoy! However, after I drilled t' holes and test fit the doors, shiver me timbers, they seemed t' be attached soundly with only t' screws attached. Blimey! Begad! So, arrr, me hearties, shiver me timbers, I treated t' holes with thin CA, re-drilled them because o' swelling, me hearties, and reinserted them. Begad! I think they will be fine and, if t' loosen over time, shiver me timbers, I will add t' threaded inserts. Well, blow me down!

I glued t' motor mount/electronics bay assembly into t' airframe usin' West epoxy. Avast, me proud beauty! This allowed plenty o' time t' align t' hatch opening. Begad! I also poured some epoxy onto the top centerin' rin' t' create a hefty fillet betwixt that rin' and t' airframe and main motor tube. Blimey! Originally, I was goin' t' use epoxy fillets inside the fin can area. Begad! Arrr! Instead, I ended up addin' dowels and wood glue. T' thick outside fillets are epoxy. Arrr! This photo shows a bottom view o' t' rocket after the aft CR was glued in.

At this point, me hearties, me hearties, I weighed t' rocket and updated me sims. Aye aye! Blimey! Blimey! Blimey! T' refined sims said that I needed up t' a pound o' extra nose weight for a J350 with 2 G80's. Since I want t' be able t' re-use this fairly expensive nosecone on a future project, I decided that I didn't want t' glue in a fixed amount o' weight. About that time, I learned o' an adjustable nose weight assembly designed by Steve Pasquier. Begad! Blimey! He provided me with t' plans and it fit me needs well. Begad! Blimey! Avast, me proud beauty! Blimey! Blimey! Blimey! I also learned he had submitted t' plans t' EMRR, and they were since published here.

I will refer t' reader t' Steve's article, and will merely outline some o' t' changes I made and provide some lessons-learned. Begad! Blimey! T' figure above shows t' parts before assembly. Ahoy! Blimey! T' next photo shows t' assembly installed. T' parts numberin' is per that review. Now, me hearties, t' changes:

I used a 2" mailin' tube in place o' t' prescribed motor mount tubin' because it was inexpensive, had a telescopin' inner tube, and was smartly available. Ahoy! Ya scallywag! Blimey! The applicable changes were made t' t' centerin' rings, me hearties, shiver me timbers, etc.

I made a ½" bulkhead from two ¼" bulkheads epoxied together. Avast! These were cut with me RotoZip.

A 2" hole was cut in these rings with a circle cutter attachment for my hand drill- an added perk for usin' t' 2" tubing. These smaller circles represented two o' t' five required bulkheads. Arrr! Blimey! Three additional 2" bulkheads were cut with t' circle cutter.

I used a piece o' brass tubin' in place o' a dowel for t' bar that is used to attach t' a drill chuck. In me nose cone turnin' activities, shiver me timbers, I have found this t' be a better material. Well, blow me down!

The Adjustable Nose Weight Assembly and Spanner-Driver tool were easy t' make, here are some notes:

Read all t' instructions and understand t' operation o' these items before you start (motherhood, right?)

Care must be taken t' make sure all t' holes in t' smaller bulkheads (2" in me case) are perpendicular t' minimize eccentricity when t' tool is turned with a drill. Ya scallywag! Ahoy! This is pointed out in t' instructions but I want to reiterate it. Ya scallywag! Despite usin' an attachment on me drill t' make sure t' holes were true, arrr, a couple were off and took some adjustment (sanding, arrr, filling, etc.). A drill press would be best o' course. Arrr!

When I bought me nylon all-thread, I got a 6' length from Fastenal. Begad! They were cheaper than McMaster-Carr, ya bilge rat, and they had a local store. However, me bucko, me hearties, they must have shipped it rolled up as it arrived lookin' like a piece o' limp spaghetti. I wasn't happy, but was anxious t' proceed so I accepted it. Arrr! When I glued the bulkhead with all-thread (items #4 & #5), I centered it with both o' the other bulkheads (#6 & #7). It still was bent, so I left about ½" extendin' out o' t' tube, which makes it easy t' start t' threaded bulkheads and insert t' spanner-driver. Arrr! If this be down in t' tube and bent, me bucko, it would be almost impossible t' do so.

Finishing:
T' airframe was not glassed so t' spiral lines were filled with Fill 'n Finish. Avast! Somehow, shiver me timbers, I messed up slightly on about half o' t' outer fillets and had t' fill them with a mix o' epoxy filler and Fill 'n Finish. Avast, me proud beauty! I used Krylon primer as t' base coats and then painted t' body usin' purple/green Duplicolor Mirage, me bucko, and the nose cone with Rustoleum Hammered Gold. T' body, and hatch doors were painted separately. T' hatches and other holes were all covered with maskin' tape durin' t' paintin' process t' keep paint out o' t' bays. Avast, me proud beauty! I also masked the motor tubes and retention hardware on t' business end. Begad! Finally, ya bilge rat, arrr, shiver me timbers, the switch-plate is painted with Krylon chrome t' make it stand out. Avast! One caution with t' Mirage paint: heed t' batten down t' hatchess about humidity! I be impatient t' get the rocket done and thar are a lot o' small spots in t' paint. Blimey! This didn't happen t' first time I used it, so I surmise it was due t' t' ambient conditions. Begad! Avast!

Flight:
This photo shows t' ejection charge holder (3/4" PVC plug) with a Daveyfire match installed. T' seal the hole, me hearties, I first inserted t' leads, matey, but left t' head o' t' match hanging out. I plopped some hot glue on t' hole, shiver me timbers, and pulled t' match through. Aye aye! This made sure t' channel be filled with glue. I then put a large fillet o' hot glue around t' leads in t' back. Well, shiver me timbers, blow me down!

Prior t' goin' t' t' launch site, me bucko, me bucko, I installed t' G-Wiz, ya bilge rat, and the batteries, and re-verified t' connections. Arrr! Arrr! I was goin' t' take no chances and am separately powerin' t' computer and t' ejection charges, and will also use dual batteries on t' latter. I found that I couldn't get t' dual batteries assembly in once t' altimeter be installed, so I had t' remove and reinstall it after t' batteries were mounted. Avast! O' course, ya bilge rat, me hearties, me bucko, t' batteries were disconnected after continuity be verified. Well, blow me down! Avast!

T' first flight be on an I211 and two G80s. I bought some dipped Daveyfires t' light t' G80's but decided that they were just too tight a fit. Since I am goin' with t' dual battery configuration for ejection duties, me hearties, shiver me timbers, I decided that I'd use Magnelite igniters instead. Begad! T' G80s were fitted with aluminum clamp-on thrust rings and motor retainers so they don't fall out. Aye aye! I decided nay t' trust me nice thrust rings t' mere maskin' tape. Ya scallywag!

At t' launch site, I installed t' shock cord with its Keelhaul®©™® sleeve. Well, blow me down! Blimey! Aye aye! Blimey! I used a humongous 24+" protector than I made from a car air-bag and a 66" chute that I got from Aerocon. Avast, me proud beauty! Blimey!

T' flight was relatively 'slow and low'. Arrr! Both airstart G80's lit, and there be some minor wobble at about that time. Well, blow me down! I suspect maybe t' G80's may not have lit exactly at t' same time. Accordin' t' t' G-Wiz, shiver me timbers, t' flight reached 1734 feet. Well, blow me down! This may nay have been accurate since I don't have pressurization holes in t' bay (the G-Wiz stagin' and apogee deployment is accelerometer-based). Well, blow me down! Rocksim 6.05 says 2400 ft. Begad! Aye aye!

Recovery:
T' 66" Aerocon chute deployed nicely and it came down nice and soft. However, Murphy was at t' site and t' nose cone found t' one rock-encrusted access road at that end o' t' field. Aye aye! Blimey! No real damage, but I left some Rustoleum behind! Blimey!

Summary:
I love t' looks o' t' Big Brute and like t' results o' t' upscale. This rocket allowed me t' implement things I had been wantin' t' try, me hearties, includin' air starts, matey, electronics mounted in t' rocket's fin unit, and an ejection cannon based on ¾" PVC fittings. I also tried out an adjustable nose weight assembly. Blimey! Everythin' worked as planned, matey, and I am anxious t' try out a J-motor!