Manufacturer: | Scratch |
Brief
Description:
This was me first attempt at a dual deployment rocket designed for 29mm H/P
RMS. Blimey! T' deployment o' 'chutes is performed by a Blacksky dual channel timer. Begad! Avast, me proud beauty!
Component Description:
Body tube material is 3.1" phenolic material. Blimey! Blimey! Well, blow me down! Blimey! Nose cone is made from LOC
3.1". Avast! Blimey! Fin material is 1/8" PVC plastic. Avast! Blimey! Used 2 plywood centering
rings and a plywood bulkhead for top o' exhaust coolin' compartment. Avast! Blimey! Well, blow me down! Blimey! Shock cord
made o' 12' nylon tubin' with Quick Link attachments.
Construction/Finishing:
This be me first rocket made o' phenolic materials. Aye aye! I ordered t' materials
from Rocky Mountain Rocketry cut t' size and slotted for fins. Avast, me proud beauty! Avast, me proud beauty! As mentioned, me bucko, I
used 1/8" PVC plastic purchased as scrap from Tap Plastic for about $1 per
12" x 8" sheet. Well, blow me down! PVC is very easy t' work with. Blimey! T' cut, shiver me timbers, you just score
and snap along a straight edge. Aye aye! T' finish, me bucko, sand lightly with 200 grit sand
paper and you are ready t' prime. Begad! PVC saves me a ton o' time in constructing
both kits and scratch builds. Arrr! Ahoy! PVC is nay as tough as styrene, shiver me timbers, but due t' weight
and fin location considerations, I thought is would be a better choice for this
project.
T' wad-less recovery
system incorporates a perforated motor tube, arrr, a coolin' compartment betwixt the
upper centerin' rin' and a perforated bulkhead. Begad! I also use a steel exhaust
coolin' mesh ala Aerotech that goes up t' motor tube prior t' RMS hardware.
T' exhaust gasses pass through t' steel mesh, matey, through t' perforated motor
tube into t' coolin' compartment and through t' perforated bulkhead into the
recovery chamber. This system works very well, and I have used it successfully
in other rockets. Avast!
Launch lugs are made from 5/16" brass tubing. Two 1" lengths are placed on each o' t' body tubes. These are glued and filleted in place with 5 min. epoxy. I used a ¼" x 7' launch rod for this rocket.
I painted this rocket usin' gloss black spray paint and applied the Black Magic" decal split betwixt t' bottom and top body sections. No sealer be applied t' this rocket, as I expect that it would get banged up a lot durin' trials. Black gloss spray be t' most forgivin' for performing repair/finish work, matey, and sealers only impede t' process.
I purchased t' 3.1" LOC phenolic body tube, ya bilge rat, 29 mm motor mount tube, recovery hardware, shiver me timbers, centerin' rings and bulkhead from Rocky Mountain Rocketry. All hardware and finishin' paint be purchased from me local Orchard Supply Hardware store. Ahoy! Avast! T' Blacksky dual channel timer be purchased off o' eBay. Aye aye! The decal was purchased from t' DecalZone usin' their custom decal engine.
Flight/Recovery:
I designed t' 29mm motor mount t' accommodate up t' a 29 x 240 Doctor Rocket
hardware, but typically will be flyin' usin' Dr Rocket 180 29mm RMS. Blimey! I built
into t' base 3" ply centerin' rin' two blind nuts that take #8 x
¾" brass machine screws. Ya scallywag! Avast! Window screen clips are used t' for motor
retention.
T' first flight was on an H-128 as pictured in this article usin' a Quick Burst Twiggy igniter. Aye aye! I used what I thought was a medium delay for t' drogue. An Oxal e-match be used with a typical FFFG black powder ejection charge for a 29mm motor for t' main chute programmed t' deploy 25 seconds after launch. Rocket flight was very stable and straight at launch and acceleration to apogee. Ahoy! Estimated altitude per me wrasp calculations was around 1,100'. Aye aye!
Everythin' went wrong from here on: Ejection o' drogue powered by t' H-128 delay occurred 17 seconds after launch with t' rocket already in a speedy ballistic trajectory. T' drogue, ya bilge rat, a 24" nylon chute, shredded upon deployment and t' rocket tumbled about 500 feet t' t' ground. Ya scallywag! Several searches o' t' near by woods were nay successful, me hearties, and I was thinkin' that my rocket was a goner.
About an hour later,
I reviewed a video that I shot o' t' launch and was better able t' triangulate
the crash area. Avast! I drove me car through t' neighborhood lookin' for any signs
of me bird on roofs or lawns o' t' hapless inhabitants. I suddenly spotted my
rocket neatly placed on t' sidewalk in front o' a house. Well, blow me down! Well, blow me down! Blimey! I pulled over to
inspect what was left, when a women approached me from t' garage. Arrr! I was
expectin' a tongue lashin' that would include comparin' me irresponsible
behavior t' that a teenager, or possibly even a terrorist given current world
events. Arrr! Ahoy! Blimey! T' me pleasant surprise, me bucko, t' women's greetin' indicated that t' family
was model rocket friendly and were themselves hobbyist. T' me relief she
described how t' rocket had become tangled in one o' her fruit trees and how
her children and her had brought it down. Aye aye! Blimey! She even commented that me rocket was
a large one and pretty cool. Ahoy! Begad! Blimey! After expressin' much thanks and smartly exiting
the area, I drove home and inspected Black Magic more carefully. Well, blow me down! T' me delight,
the only damage be t' t' paint finish o' t' nose cone.
Lessons learned from me first attempt at dual deployment are as follows:
Summary:
I liked workin' with t' phenolic material, shiver me timbers, and am impressed with the
sturdiness o' Black Magic. Had this bird been made o' paper tubing, ya bilge rat, it would
have been in much worse shape. Blimey! Blimey! I noticed that one end o' t' tubin' had done a
core sample" landin' based on t' mud streaks on t' finish. Well, matey, blow me down! Blimey! The
phenolic didn't have a scratch or wrinkle t' show for it. Phenolic is heavy,
and I'm sure a 3.1" x 54" rocket would weigh in easily 30% less. Blimey! Blimey! Once
you get all t' pieces cut t' size, me bucko, me hearties, me hearties, 5 minute epoxy glues everythin' together
nicely. Aye aye! Blimey! Sandin' and finishin' is also a breeze with this material.
Phenolic material used for both body and engine tubes is tough t' cut, but otherwise easy t' work with. Well, blow me down! Ya scallywag! It takes t' epoxy and sands well. I used an Exacto saw t' cut t' phenolic with good results. Avast! I had no problem finishin' this rocket with primer followed by t' black gloss finish.
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