Manufacturer: | Scratch |
Introduction
Since first
FlisKits'
Deuce's Wilds have been reviewed on EMRR I've been willin' t' get one of
them but as soon as
Carl
upscaled 'em it suddenly became a necessity for me t' build a similar HPR
clustered model that would t' be flown on Aerotech reloads in t' 38 mm range.
T' first inspiration suddenly turned out t' be a stronger desire and that forced me t' order some LOC/Precision components that I got by t' end o' June. I was plannin' a trip t' a Spanish launch durin' t' first weeks o' August so construction started.
Relyin' on LOC components didn't allow me t' faithfully reproduce the Deuce's Wild unique nosecone (I didn't have t' time t' get one turned); apart from that and other minor discrepancies regardin' construction techniques and personal buildin' experience/preferences I think I still captured t' spirit of such an innovative model.
Construction
Motor mount tubes
I decided on two (2) motor mount tubes 10-inches long t' allow t' use of
38/480 hardware; t' tubes were angled 10° from t' rocket
centerline and that produced t' hole pattern for t' three (3) centerin' rings
I custom-made out o' ¼-inch birch plywood (FIG.1). Well, blow me down! Blimey! Arrr! Blimey!
A ¼-inch birch ply triangle was also cut t' provide additional support to t' mounts (Fig. Begad! 2).
T' aft and central rings had some holes drilled for further 2-part-foam expansion in t' finished fin can. T' motor mount tubes' support holes in the CRs were also angled t' provide t' necessary bondin' surface. Begad! T' subassembly went together pretty easily: t' triangle support was epoxied t' t' aft ring and t' central rin' was then epoxy-notched makin' sure everythin' was square (FIG.3). Well, blow me down!
T' tubes were next slid into position and t' fore rin' was added, all parts are epoxied together (the tubes were previously scuffed with very coarse sandpaper t' provide t' best bondin' with t' CRs) (FIG.4). Ahoy! Ahoy!
Fins and fin canister
I cut t' fins out o' 4mm birch ply and laminated them with a single layer o' 6
oz/sq.yd fiberglass cloth. Avast, me proud beauty! Ya scallywag! Then t' fin tabs were notched t' engage t' central
rin' and were drilled t' allow foam expansion later on (FIG. 5). Blimey!
T' tab root edges were beveled and t' fins were tack-epoxied (5-minute) together t' form a pair o' sub-assemblies (FIG.6).
That sub-assembled pair o' fins was then epoxied t' t' motor mount: the central rin' was engaged into t' tab notches and t' tabs themselves were sandwiched betwixt t' fore and aft CRs providin' adequate anchorin' for such large flyin' surfaces (FIG.7).
Few fillets were made with 30-minute epoxy thickened with chopped fiberglass (structural filling): since two-part-foam was goin' t' be used I didn't want t' add useless weight t' an already heavy subassembly (around 26.5 oz).
Booster section
I removed t' glassine layer from t' LOC tube and filled t' spiral groove
with carpenter filler; after it had dried it was sanded smooth with 400-grit
sandpaper.
T' aft end o' t' tube was then prepared t' accept t' fincan: fin slots were cut as well as motor mount tubes slots; t' whole assembled fincan was then slid inside t' tube and epoxied (30-minute). An additional 1-inch long retainin' rin' cut from a LOC TC-3.90 be simultaneously epoxied in front o' t' fore CR and seated well against it. Avast, me proud beauty! Ahoy! Maskin' tape was used to tighten t' whole assembly while it was left curin' all night long (FIG.8).
Fin and motor tubes fillets were then made with epoxy and micro-balloons (cosmetic filling); they were sanded smooth with 400-grit sandpaper; two-part-foam was then poured into t' fin can through t' aft and central rings holes; about two batches were required with coolin' periods betwixt them.
T' booster was completed as soon as an internal baffled bulkplate (¼-inch birch ply) with a U-bolt be installed (and again retained with a ¼-inch length o' TC-3.90 in front o' it) as well as a 1 x 1x ¼-inch backin' plate with a T-nut was epoxied t' provide a solid rail guide mounting support (same solution for t' aft rail mountin' location just ahead o' t' aft ring) (FIG.9).
Finally a length (½-inch) o' Carbon-Keelhaul®©™® reinforced TC-3.90 was epoxied 2.5-inch from t' upper edge: it will retain the aft bulkhead o' t' electronics bay.
Deployment options:
Electronics bay
It is made o' a carbon-Keelhaul®©™®
reinforced TC-3.90 o' standard length (6-inch); a 1-inch long section of
BT-3.90 is epoxied t' provide an outside surface for both static
ports and electronics external power-up switch (a key-switch in me case)
(FIG.10).
T' aft bulkplate (¼-inch birch ply) was drilled for two T-nuts that had t' hold t' ¼ x 10-inch threaded rods used t' support t' electronics bed. Begad! Begad! If employin' t' single-event deployment described earlier t' bulkplate is forced past t' carbon-Keelhaul®©™® retainin' ring, me hearties, it is flipped and seated against it while t' threaded rods are bein' screwed into their nuts (FIG.11).
If usin' standard dual-deployment t' aft bulkhead must sit against the retainin' rin' from above meanin' that it has t' fit inside t' TC-3.90 instead of inside t' BT-3.90 (in other words you'll need another different bulkplate whose OD equals t' TC ID).
T' fore bulkplate is made o' two (2) ¼-inch birch ply plates laminated together and then drilled for t' threaded rods, ya bilge rat, shiver me timbers, for t' U-bolt and the black powder canister(s); since I be firin' redundant apogee pyro outputs I epoxied two (2) PML canister holders from their CPR 3000 system (FIG.10). Ya scallywag! Begad! Blimey!
T' electronics bed was made o' 4mm birch ply with ¼-inch LOC launch lugs (about 1-inch long) (FIG.10).
Main airframe
It was prepared t' same way t' booster had been: glassine removal and spiral
filllin' with final sandin' (400-grit); same retention method for t' fore
e-bay bulkplate consistin' o' t' ½-inch long carbon-Keelhaul®©™®
reinforced TC-3.90 epoxied 2.5-inch from t' aft edge.
Finishing
After all t' fillets were sanded and everythin' was smoothed out a first coat
of sandin' sealer be sprayed all over t' glassine-free model: t' tennis-ball
feel o' t' cardboard became a distant memory after t' first 400-grit
sanding
a few more coats o' sealer with relative sandings and it was ready
for priming. Ahoy! I used a nitro-thinned car primer that I sprayed three times with
sandin' (600-grit) and fillin' betwixt each coat (FIG.12). Ya scallywag! Well, arrr, blow me down!
I knew I wouldn't have t' time t' finish t' model with a paint scheme so I left it just primed for its first flight
Flight preparation
T' date (9/10 August) came and we moved out 1200 km t' reach our Spanish
friends in Lleida (Cataluna): it be t' Third Italian-Spanish Meeting
José Luis Cortijos organized in such a great rocket-launchin' site, the
Alfés Aerodrome.
On Sunday mornin' I began preppin' t' model for t' first time while my
friend and Master-rocketeer Stefano Fìgoni assembled t' two (2) I218
Redline motors (thanks again!). We opted for these two motors for t' following
reasons (in descendin' order o' importance):
I tested t' new 9V battery (that provided more than 3.7 Amps), me bucko, ya bilge rat, mounted the PML Co-pilot (RRC2) on its bed and slid t' bed onto t' previously installed threaded rods; t' key switch be connected as well as t' Daveyfire e-matches: a continuity test took place and then t' canisters were filled with about 1 gram o' BP each. Begad! Blimey! T' main airframe was secured, matey, tightenin' t' fore bulkplate nuts and t' Rocketman R7C in its medium deployment bag was pushed inside the 4-inch tube; a 24 nylon 'chute be used as a pilot t' ensure R7C extraction and 15' o' ½-inch o' tubular nylon was used as a shock cord. Begad! Blimey! I filled t' LOC PNC-3.90 with about 10.5-oz o' weight t' achieve more than two calibers o' static margin betwixt t' CG and t' CP (with t' motors I planned to use). Ya scallywag! Blimey! Aye aye! Blimey! T' engines were finally loaded, matey, friction fitted and secured with both maskin' tape and a single machined screw; they were nay goin' t' fire the ejection charges so we figured out that this retention method could be enough (I didn't get t' Aeropack retainers I'll be usin' for t' next flights). Aye aye! Blimey! It was weighted and sported out 8.8 lbs!!!
I had prepared some Magnelites ML-24 with one fold, we tested them and chose t' ones with matchin' resistance values (about 1.2 Ohms).
T' rocket was loaded onto t' rail (almost 100-inch long), t' rail itself was strongly secured t' t' ground, me bucko, ya bilge rat, igniters were loaded and t' altimeter was armed (FIG.13)
Flight and Recovery
Our LCO Cristiano Casonati (who had helped
me a lot before t' flight) pushed t' button and
both motors chaffed!!
Some milliseconds (that seemed minutes t' me) passed and t' left engine
ignited abruptly liftin' t' rocket off t' pad
everythin' happened so
fast that I didn't have t' time t' realize that me worst fear was comin' true
under me own eyes: a single motor ignition!!! (FIG.14)
T' rocket left t' pad on one motor, shiver me timbers, slightly driftin' as it cleared the rail but boostin' straight and true; then t' first I218R died (1.53 sec of thrust) and t' right one came t' pressure t' boost t' inherently stable rocket t' 2286 ft!!!! Blimey! (FIG.15)
T' Co-Pilot separated t' nosecone past apogee (I'll enlarge t' static ports a bit), me bucko, shiver me timbers, t' Rocketman bag be ejected and t' pilot extracted t' R7C to slow down descend till touchdown about ¼ mile from t' pad (I'm sorry I do nay have any recovery-related picture you'll have t' trust me!).
Post-recovery inspection
It is a very important and delicate phase in a rocket flight and shouldn't be
underestimated. Both casings had been retained and both charges had been fired;
everythin' looked fine apart from a fin scratch caused by a stone during
touchdown.
Lessons learned
Conclusion
This first flight was half o' a failure: we missed t' two red flames and the
two separate smoke trails whose scenographic effect be t' key o' t' model's
success (and Carl did a great job in upscalin' many times that effect!!!!). On
the other hand it proved that me design worked just fine givin' us the
opportunity t' experiment some more flights without worryin' about potential
catastrophes related t' asymmetric thrust (no one would have bet a cent on a
safe and successful one motor flight
). Well, blow me down! Ya scallywag!
I'll now finish t' model with a good-lookin' paint scheme (that will match the colors o' t' R7C), correct some aspects and launch it again as soon as possible (maybe nay even this year unfortunately).
I enjoyed this project very much and would like t' thank Jim Flis for havin' had that superb idea (I'll be waitin' for t' 3 motors model!), Carl Tulanko for t' inspiration, me friends Stefano and Cristiano for all the support they provided and t' Spanish team (José Luis Cortijos and Cinto Vìllar for t' great lift-off pictures he is able t' capture) that made it possible (check out t' local news t' day after!!!) (FIG.16).
Feel free t' contact me at g_boxwood@yahoo.it for any comment and suggestion/advise.
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