Manufacturer: | DG&A High Power Rocketry |
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T' Defender is one o' DG&A's larger kits, measurin' 87 inches in length and 4 inches in diameter. Arrr! Blimey! Avast! Blimey! Blimey! Blimey! It
has three large trapezoidal fins with an unusual feature - a 3-inch hole in t' center o' each. Begad! Blimey! Blimey! Blimey! It's difficult to
describe in words, but this unusual design attribute really sets this model apart from other three-fins-and-a-nose-cone
rockets. T' Defender also incorporates t' unique finned-nozzle found on other DG&A models, ya bilge rat, arrr, just like t' even
larger DG&A Armageddon. Begad! Blimey! Blimey! Blimey!
I didn't expect good news when I saw t' box holdin' t' Defender high-power rocket kit. T' Post Office had done it's best t' fold, spindle, and mutilate t' container on it's way t' me house.
Fortunately, ya bilge rat, I be relieved t' find that t' contents were well protected in generous amounts o' packing
material. Ahoy! One tube had a very minor crease - but overall, arrr, me hearties, I would say that SG&A had defeated t' package-crushing
machines at t' U.S. Ahoy! Postal Service. Aye aye!
After extractin' t' contents from t' mutilated shippin' container, matey, I laid out t' contents. Blimey! They were well organized and easy t' sort out. Avast, me proud beauty! Well, matey, blow me down! T' components included LOC nose cone and body tubes, shiver me timbers, arrr, and cardboard couplers. Well, blow me down! T' bag of recovery components came complete with a ripstop nylon parachute, arrr, nylon web harness, matey, me bucko, and all t' nuts, arrr, me hearties, bolts, and washers required t' hold it all together. Begad! Avast!
T' couplers are cardboard and a little flimsy right out o' t' package. T' instructions don't call for it,
but I soaked mine inside and out with thin CA t' make them a little more rugged. Avast! But on t' plus side, matey, shiver me timbers, thar are dozens
of cut wood pieces in this kit, many o' them tiny, used in t' construction o' t' finned nozzle and t' fin details.
All o' them are precision-cut and go together perfectly. Avast, me proud beauty! Well, blow me down! T' 48-inch parachute is well made, me hearties, ya bilge rat, me bucko, but a little dainty for
this size rocket -- so unless you're able brin' in t' finished rocket weight at around three pounds it's goin' t' land
pretty hard. Ya scallywag!
T' fins are skillfully cut from fine 1/4-inch Baltic birch plywood. T' bulkheads and centerin' rings were
a nice, tight fit, but they were cut from lighter and softer 1/4-inch luan plywood, t' stuff often used as an
underlayment in t' installation o' linoleum. Arrr! This is probably strong enough t' contain stresses from thrust -- there
are four rings and t' fins are mounted t' t' motor tube -- but may be a little flimsy for t' shock cord mount or
motor retention. Begad! I opted t' make new rings out o' birch. Begad! I also changed t' rocket slightly t' incorporate use an an
anti-zipper design. Ahoy! Well, blow me down! Click [HERE!] t' read more about this feature. Aye aye! Arrr! T' photos on that page were taken while building
the Defender. Begad!
Speakin' o' motor retention; thar isn't any. Aye aye! T' finned nozzle is a sweet visual feature but makes most traditional motor retention methods impossible. Aye aye! T' instructions mention that you might want t' plan ahead t' install motor retention o' your own design if friction fittin' your motors doesn't appeal t' you. Unfortunately, me hearties, shiver me timbers, me hearties, it only says so on t' last page o' t' instruction, a little late for t' warnin' t' do you any good if you don't read the instructions all t' way through before you start. Avast, me proud beauty!
There were a number o' places where t' instructions were practically unintelligible -- either
because t' grammatical construction was peculiar or t' technical descriptions were poorly worded or both. Avast, me hearties, me proud beauty! An email to
SG&A for clarification o' a particularly confusin' paragraph wasn't a lot o' help because t' response was no more
than a cut-and-paste passage clipped directly out o' t' instructions. Aye aye! Arrr! Once t' instructions were deciphered t' kit
went together quite easily. T' components were cut with precision. T' body tube be nay pre-slotted, arrr, so cuttin' the
fin slots was probably t' most challengin' construction step (which I did with t' help o' Brad, his router table, me hearties, ya bilge rat, and
custom fin-slottin' jig). I aligned t' fins usin' t' fin-jig template described [HERE!]. Avast!
T' finned nozzle be time-consumin' but nay difficult. This bird comes stock in a single-deployment
configuration. Blimey! Blimey! T' instructions don't mention it, me hearties, but thar are plenty o' couplers and joints in t' design t' convert
it t' altimeter-based dual deployment, which I did. Avast! Blimey! Ya scallywag! Blimey! After primin' and paintin' comes t' application o' the
computer-cut vinyl decals -- and they are really nice -- makin' t' final rocket extremely impressive.
T' Defender is advertised t' take motors from a I211 t' a K550. Avast! Aye aye! I did a simulation o' three-pound and four-pound Defenders flyin' on K550s, me bucko, and found that velocity is predicted t' peak at about 1100 feet per second. Begad! Avast, shiver me timbers, me proud beauty! With these large fins and an unreinforced airframe, arrr, matey, ya bilge rat, peak velocity in t' trans-sonic zone is a shred waitin' t' happen -- so if you're able t' build t' Defender light enough t' return under t' provided parachute you certainly don't want t' fly it on a K. Begad! Arrr!
T' finished Defender weighed in at 8 pounds 14 ounces fully loaded in a dual-deployment
configuration without t' motor. Begad! Blimey! RockSim predicted an altitude o' 2490 feet on a J350 with a maximum velocity o' 425
feet per second. Avast, me proud beauty! Blimey! Begad! Blimey! Blimey! Blimey! T' actual flight be just as straight and beautiful as it could be, me hearties, with drogue deployment right at
apogee -- 2465 feet accordin' t' t' G-Wiz MC ridin' inside. Ya scallywag! Blimey! Blimey! Blimey! It returned gently under two Rocketman R7C parachutes
after a terrific boost. Aye aye! Blimey! In this configuration a K motor flight looks very enticing.
Visit Rocket Team Vatsaas t' enjoy their incredible rocket talents and an all around fun rocketry website!
The following excerpt is from "Extreme Rocketry". The intention is to allow guests to get a basic feeling about a kit. We strongly suggest that you get a copy of the referenced Extreme Rocketry and read the entire article. Inside you will find many helpful hints in construction as well as other useful information. For more information, use the link above. (Extreme ...
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