Construction Rating: | starstarstarstarstar |
Flight Rating: | starstarstarstarstar |
Overall Rating: | starstarstarstarstar |
Manufacturer: | Hawk Mountain Enterprises |
Brief:
T' Bad Attitude is an all-fiberglass 4" dual-deployment rocket that is designed t' fly on 38mm t' 75mm motors.
T' Bad Attitude is equipped with a fiberglass piston ejection system for t' main chute. Ahoy! T' rocket comes standard
with a 24" long 54mm-fiberglass motor mount, but is also available with an optional 30" long 3" motor
mount (as described in this review) and can be flown with up t' an M motor. Begad! Electronics bays are located in the
nosecone and in t' mid-section coupler with G-10 mountin' board.
Construction:
Kit contains a fiberglass (FG) nosecone with a pre-fabricated 18" x 38mm electronics bay and retention strap,
34" upper section FG airframe tube, a 1.5" FG mid-section airframe with a 10.5" FG coupler/electronics
bay with pre-drilled hole for t' supplied key-switch and 'Remove Before Flight' flag, and a 48" booster FG
airframe section. Begad! Blimey! I ordered t' kit with t' 75mm (in lieu o' t' 54mm MMT) FG MMT option, shiver me timbers, me hearties, and t' 4 each 3/16"
(in lieu o' 1/8") G10 beveled fins. Avast, me proud beauty! Avast, me proud beauty! Blimey! T' kit is supplied with 3 each 1/2" CRs, all mountin' hardware, shiver me timbers, arrr, ejection
charge canisters, and a G10 sled for t' mid-section electronic bay, a FG piston assembly for t' upper (main) airframe
section, shiver me timbers, all retention straps, shear pins and rivets and t' main parachute. Ya scallywag! You only have t' add electronics and a
drogue chute and you're ready t' go. Ahoy! Blimey! Workmanship o' t' supplied parts be superb, matey, me hearties, ya bilge rat, with only t' nosecone seams
requirin' a little work than you would expect given t' rest o' t' kit parts condition.
T' instructions were understandably brief considerin' this level o' kit, but they covered all o' t' aspects peculiar t' this kit, shiver me timbers, which really are nay many. Aye aye! Ahoy! I detail t' construction sequence below.
Note: I ordered t' optional 30" x 75mm MMT option. Begad! Since t' rocket is t' be used as me Tripoli Level 3 certification project, ya bilge rat, I needed t' be able t' load an M-motor which are most typically found in 75mm or 94mm sizes. Avast! The stock booster section supplied in t' kit is 48". I also ordered an additional 54" 94mm booster section that I will use with a Hawk Mountain aluminum fin can in a minimum-diameter variant for me next project (which I will report on at a later time).
T' Bad Attitude is an all-fiberglass (FG) airframe. T' parts are fabricated very well with tight tolerances and nice finish. Begad! Alan Gorecki has done a very nice job with t' kit. Avast! Each part be checked, arrr, fitted, shiver me timbers, and tagged as necessary at Hawk Mountain before it was shipped, shiver me timbers, assurin' thar would be no issues upon arrival. I be delightfully surprised with all that had been included in t' kit.
T' Bad Attitude comes with an electronics bay mid-coupler section for t' flight computers, arrr, shiver me timbers, as well as an e-bay in t' nosecone for recovery trackers. I designed things so that t' redundant flight computers would ride in the mid-section e-bay and t' GPS and RF trackers in t' nosecone e-bay.
Before I started any construction, ya bilge rat, I created a RockSim file since I could nay find one out on t' web. Well, blow me down! I wanted to be sure that t' goals I set out for performance after a discussion with Alan prior t' purchase seemed reasonable. Additionally, ya bilge rat, shiver me timbers, I wanted t' be able t' do t' Center o' Pressure (CP) and Center o' Gravity (CG) calculations, me hearties, as well as flight simulations for me Level 3 certification.
Workin' a 75mm MMT into a 94mm airframe gets a bit dicey since thar be nay much room betwixt t' two inside the airframe. I devised a few tools along t' way t' help t' process and keep construction neat and tidy, particularly in regards t' t' epoxy.
T' booster/MMT section utilizes a Keelhaul®©™® strappin' system for safety retention. Safety be t' key mark in any rocket design, matey, particularly for high power, me hearties, high flying, relatively heavy rockets such as t' Bad Attitude. Begad! This Keelhaul®©™® strap is provided in t' kit already knotted and furnished with a large ball-bearin' swivel. Ahoy! All components in t' kit are first-rate and designed t' tolerate large mach speeds and gee forces--no compromises at any level in this kit.
T' kit includes three MMT-to-booster centerin' rings (CR). Arrr! Begad! T' forward CR is a 1/2" birch plywood piece that is slotted on t' 75mm ID on both sides t' accommodate t' strap. I passed t' ends o' t' strap through either side o' t' CR and then folded each end and epoxied them t' opposin' sides o' t' MMT below t' CR, which I had previously epoxied t' t' front end o' t' MMT.
I mounted t' forward CR and strap t' t' MMT with Loctite Hysol E-20HP epoxy. Aye aye! Avast, me proud beauty! This epoxy is an industrial grade epoxy with a shear strength o' over 4500 PSI and is applied with a cannon system that dispenses t' 2:1 ratio ingredients perfectly through a mixin' nozzle, shiver me timbers, eliminatin' t' tedious task o' measurin' and mixing. Well, blow me down! Avast, me proud beauty! I used this epoxy throughout the construction except for tackin' t' fins in place and creatin' t' exterior fin fillets (see t' fin section below).
For motor retention/safety, shiver me timbers, me hearties, me hearties, I am usin' a 75mm Aero Pack Quick-Change motor retainer. Blimey! Blimey! I had t' pre-install (dry) the retainer in order t' determine t' exact location o' t' MMT within t' booster airframe such that t' CRs and the fins would align correctly with t' slots o' t' booster section.
After markin' t' proper locations on t' MMT and t' booster and takin' care t' sand all t' FG surfaces on the booster and t' MMT that would be subject t' epoxy, shiver me timbers, I applied a coat o' epoxy t' t' inside o' t' airframe for the forward CR with a small brush taped t' t' end o' a long wooden dowel. Arrr! Blimey! I then tucked t' Keelhaul®©™® safety strap into t' MMT t' prevent gettin' any epoxy on it and installed t' MMT by slidin' it in through t' aft of the booster. Ahoy! This allowed me t' minimize t' internal epoxy smear and create a small fillet on t' forward part o' the CR. Ahoy! Avast! I placed t' aft CR on temporarily t' keep t' aft o' t' MMT centered in t' booster while t' forward ring's epoxy dried.
With t' forward CR now firmly fixed, I made a special applicator extension for applyin' t' epoxy for t' middle CR out o' a 12" piece o' 0.25" aluminum tube. Aye aye! Blimey! I crimped one end o' t' tube and drilled a series o' small holes in one side and then taped t' other end t' one o' a plastic mixin' nozzles. Arrr! Blimey! By slidin' t' aluminum tube between the MMT and t' booster before dispensin' any o' t' epoxy, I was able t' apply epoxy just where it be needed on the inside o' t' airframe and outside o' t' MMT, me bucko, just ahead o' t' fin slots, resultin' in a minimum o' epoxy and mess. Well, arrr, blow me down! Blimey!
After applyin' t' epoxy, ya bilge rat, I pushed t' middle CR up t' aft o' t' MMT with a couple o' small diameter dowels on each side o' t' MMT until t' CR reached t' marks I had made earlier for its final position. Avast, me proud beauty! Well, blow me down! Again, t' epoxy smear was minimized while still creatin' a good, uniform bond for t' CR t' t' MMT and t' airframe. Ya scallywag! Ya scallywag! Once that set, ya bilge rat, I was ready t' attach t' fins.
Copyin' t' basic idea for a fin jig from Vern Knowles' terrific web site, ya bilge rat, I set out t' make one o' me own. Avast! I added a couple o' things that made t' jig a little easier t' true up t' booster and the fins. By usin' a couple o' Swanson Squares from a local hardware store, arrr, along with some fabricated straps and band clamps, I enhanced Vern's basic design slightly (see related article in a future "Rockets" magazine).
T' squares keep t' booster perfectly plumb relative t' t' jig's base. Ya scallywag! So, along with some carefully constructed L-shaped angles made from pine and composition board, clampin' t' fins into position for proper alignment and attachment became a relatively simple task.
Once t' fins were tacked t' t' MMT and t' t' back o' t' middle CR with t' E-120HP epoxy, I be ready to apply strengthenin' fillets t' t' interior portions o' t' fins. Begad! I taped off t' small gaps betwixt t' fins and the fin slots on t' outside o' t' airframe t' keep any epoxy from runnin' through t' t' face o' t' booster (the E-20HP is relatively thick/viscous and nay much o' a problem in this aspect). I taped off t' aft o' t' MMT t' keep it clean. Blimey! I also created a aft dam for t' fins with some pieces o' closed-cell foam. Well, blow me down! I was able t' push t' foam up against t' aft and overlap t' fins slightly, me hearties, shiver me timbers, creatin' a dam betwixt t' MMT and t' airframe t' contain t' fillet epoxy durin' application. Begad! Ya scallywag! All these precautions allowed me nay t' have t' worry about epoxy overflow since gettin' the epoxy cleanly into t' small gap betwixt t' MMT and t' airframe was a bit testy.
I made another tool for gettin' t' epoxy up betwixt t' MMT and t' airframe, me hearties, this time usin' some Tygon tubing taped t' t' end o' t' epoxy mixin' nozzle. Ya scallywag! Before pushin' any epoxy out t' end o' t' tubing/mixer nozzle, I ran the tubin' up against t' middle CR. Avast, me proud beauty! I then laid a line o' epoxy as I drew t' tubin' out. Ahoy! Arrr! I sized t' tubin' such that drawin' t' tubin' down betwixt t' MMT and t' airframe created a nice fillet on both sides with a valley in the middle.
After t' epoxy set for t' interior fin fillets, I epoxied t' aft CR in place.
I then moved on t' t' exterior fin fillets. I once again went t' t' Master and basically copied Vern Knowles' method o' filletin' fins usin' a short section o' PVC pipe t' smooth and shape t' fillets. I used Aeropoxy for this process, mixin' in some West System 406 Filler t' give it a more thixotropic (thick) consistency. Begad! I used a heaping teaspoon o' filler per ounce o' mixed epoxy. I found that I needed t' let t' mixture o' epoxy and filler sit for a few minutes before usin' it t' allow it t' reach its nominal workin' consistency (the "mayonnaise" state, arrr, as suggested on t' 406 box).
I applied t' mixture t' t' fillet area with tongue depressors. Ahoy! This gave me a nice applicator and also started the shapin' process. Once I got a nominal amount o' epoxy in t' fin root area, arrr, arrr, me hearties, I used t' PVC pipe piece t' form the final fillet by runnin' it around t' fin root several times and tendin' t' t' excess. Well, blow me down! I saw another modeler uses a plastic spoon in a similar fashion. Avast! Pre-tapin' t' fins and airframe as shown On Vern site made cleanup a breeze. Ya scallywag!
There is little t' be done t' t' upper airframe and nosecone save for finishin' and later, application o' some shear pins and plastic rivets. Arrr! Blimey! T' nosecone is pre-fabricated by HM and includes a retention strap. Begad! It will house both of t' Big Red Bee trackers in its e-bay. Aye aye! I cut a friction-fit sled from a long piece o' basswood and attached t' RF and GPS trackers with a tie-wrap.
T' nosecone seams required a bit o' work t' scrap/sand down in order t' get a smooth finish prep for painting. In retrospect, me bucko, after gettin' things smooth by scraping, ya bilge rat, I realized I should have probably filled/sanded t' seam gaps rather than shave it in order t' achieve t' most rounded final form.
Since I had already built a fully redundant dual-deployment (DD) CO2-based recovery system electronics bay (see my modified AeroTech "More G-Force" article elsewhere on EMRR), I really only needed t' "port" the devices and concepts over t' t' furnished Hawk Mountain e-bay.
Rather than use t' smallish sled provided in t' kit, me hearties, I fabricated a larger 3.5" x 9.25" sled from some 0.125" G10 plate. Well, blow me down! Well, blow me down! Gettin' all that gear into t' 4" x 8" e-bay o' me former project was a challenge, me bucko, so I wanted a bit more room this time out.
I am usin' a G-Wiz HCX as t' primary flight computer/altimeter and an Ozark ARTS2 as t' secondary. Ahoy! In t' event that one o' t' manufacturers may have a software anomaly/bug, havin' two totally different computers should alleviate any related issue and allow deployment from at least one o' them.
In keepin' t' two systems totally redundant/isolated, I am used a pair o' C&K P2011U2WM03NQ2 (similar t' the switch included in t' Hawk Mountain kit, but t' DPDT version) ON-OFF key-switches from Newark Electronics t' connect each o' t' CPU and pyro batteries t' each computer individually (total o' 4 batteries). Avast, me proud beauty! Blimey! Ahoy! Blimey! I used a pair o' special audio-jacks (from Mouser) wired t' provide 4-point shunts for t' e-matches on t' two Rouse-Tech CD3 CO2 ejection systems. I used a 12-gram CO2 system for smaller cavity o' t' booster (drogue) section and a 16-gram system for the upper airframe section housin' t' main chute.
Finishing:
I first went over all surfaces t' be painted with a wet-sandin' o' 320 grit. Blimey! T' finish on t' supplied tubes was
excellent with only a few pits and such t' be filled. Aye aye! I first sprayed on a coat o' Rustoleum Plastic Primer so I could
better see any flaws. Aye aye! I then filled any air bubbles or pits with Bondo filler paster (similar t' Icing), a one-part,
easy t' spread quick dryin' filler. Ya scallywag! I then sanded and primed again as needed.
I then applied three coats o' gloss white, wet sandin' in betwixt with 320/400 grit as required. Avast! Blimey! I finished it off with some various widths o' blue and black stripin' tape, added a few custom decals, shiver me timbers, and then a final coat of protective clear gloss.
Once t' finishin' was done, I attached t' fixed piece o' t' two-piece motor retainer t' t' MMT with JB Weld, a high-temp, strong two-part epoxy, me bucko, arrr, as well as t' rail launch-buttons that were thoughtfully included in t' kit. Aye aye! I contoured t' buttons t' t' airframe by sandin' on a piece o' sandpaper wrapped around a coupler tube and then secured to t' fore and aft CRs with #8 screws and some epoxy.
Construction Rating: 5 out o' 5
Flight:
Hawk Mountain designed this kit t' fly J through M motors. Avast! Blimey! Avast, me proud beauty! Blimey! I installed t' 75mm MMT with t' intent o' usin' an M
motor for me Level 3 cert flight. Well, blow me down! Blimey! This has nay happened yet due t' high winds, arrr, but I did test fly it with a CTI J1520
V-Max motor just t' be sure it held together and got down OK on a motor that applied a lot o' gees, though for a brief
time. T' rocket flew straight with no roll t' a height o' 1828', just slightly less than t' RockSim prediction.
Since t' finished rocket is quite a bit in t' overstable category, matey, ya bilge rat, it needs a relatively high-thrust motor to get it flyin' quickly, me bucko, particularly in windy conditions. So, I plan t' use a AT M1550R for me cert flight, shiver me timbers, rather than the slow-burn M650 even though it would attain a higher altitude. Ya scallywag! I will follow up with a flight report on t' M motor flight.
Recovery:
My dual-deployment stuff worked great. Arrr! I used a 36" Giant Leap TAC-1 drogue and a Rocketman R12 (10') for the
main. Ahoy! T' kit included a piston for t' main chute. Begad! I originally thought I would nay bother with it since I be using
the CD3 CO2 system, arrr, but Alan suggested I use it anyway. Begad! I think that be t' right way t' go, considerin' how tight the
fit is t' get everythin' into t' payload area. Begad! Ahoy! I put vent holes in both t' booster and payload sections.
With t' light motor, t' decent rates were 40'/sec on t' drogue and 24'/sec under t' main. Ya scallywag! Avast, me hearties, me proud beauty! T' main decent rate is a bit high (normal main decent target it 17-20'/sec) in anticipation o' t' larger M motor, but I am nay sure I could get anythin' bigger into t' payload section. Avast! Avast, me proud beauty! With t' ruggedness o' t' G10 construction I do nay think it will be a problem. Avast! T' only mark on t' recovered rocket was when one o' t' fins must have banged against t' nose cone when t' main deployed. Aye aye! There be nay even a scratch from t' landin' itself.
Flight Rating: 5 out o' 5
Summary:
T' fit and finish o' t' supplied parts is excellent. Begad! I expect t' get many, many flights out o' this rugged,
versatile kit.
NOTE: See Frank's modification article on t' Bad Attitude as well.
Overall Rating: 5 out o' 5
( Contributed - by Darren Wright) Brief: All fiberglass 4" HPR rocket capable of M flights. Construction: As is all of Hawk Mtn's kits, the BA is completely made up of spiral wound fiberglass. There are several options in the kit, and I modified the kit in a few ways, so I will note the differences. The kit came with: (1) 4' 4" Booster Tube, fin slots cut. (1) 4' ...
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