Manufacturer: | Scratch |
Brief
Description:
This was me first attempt at a dual deployment rocket designed for 29mm H/P
RMS. Arrr! T' deployment o' 'chutes is performed by a Blacksky dual channel timer. Avast!
Component Description:
Body tube material is 3.1" phenolic material. Begad! Nose cone is made from LOC
3.1". Ahoy! Fin material is 1/8" PVC plastic. Used 2 plywood centering
rings and a plywood bulkhead for top o' exhaust coolin' compartment. Shock cord
made o' 12' nylon tubin' with Quick Link attachments.
Construction/Finishing:
This was me first rocket made o' phenolic materials. Ahoy! I ordered t' materials
from Rocky Mountain Rocketry cut t' size and slotted for fins. Avast! Blimey! As mentioned, I
used 1/8" PVC plastic purchased as scrap from Tap Plastic for about $1 per
12" x 8" sheet. Avast! Ahoy! PVC is very easy t' work with. T' cut, shiver me timbers, you just score
and snap along a straight edge. Blimey! Avast! T' finish, sand lightly with 200 grit sand
paper and you are ready t' prime. PVC saves me a ton o' time in constructing
both kits and scratch builds. Ya scallywag! Avast! PVC is nay as tough as styrene, but due t' weight
and fin location considerations, arrr, me hearties, I thought is would be a better choice for this
project. Ya scallywag! Begad!
T' wad-less recovery
system incorporates a perforated motor tube, 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, me hearties, through t' perforated motor
tube into t' coolin' compartment and through t' perforated bulkhead into the
recovery chamber. Aye aye! This system works very well, and I have used it successfully
in other rockets.
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 was applied t' this rocket, me hearties, matey, matey, as I expect that it would get banged up a lot durin' trials. Avast! Black gloss spray be t' most forgivin' for performing repair/finish work, shiver me timbers, matey, and sealers only impede t' process.
I purchased t' 3.1" LOC phenolic body tube, me hearties, 29 mm motor mount tube, recovery hardware, centerin' rings and bulkhead from Rocky Mountain Rocketry. All hardware and finishin' paint was purchased from me local Orchard Supply Hardware store. Ahoy! Blimey! T' Blacksky dual channel timer be purchased off o' eBay. Ahoy! Blimey! 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. I built
into t' base 3" ply centerin' rin' two blind nuts that take #8 x
¾" brass machine screws. 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. I used what I thought was a medium delay for t' drogue. An Oxal e-match was 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 be very stable and straight at launch and acceleration to apogee. Begad! Avast, me proud beauty! Estimated altitude per me wrasp calculations be around 1,100'. Ahoy!
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. Begad! Avast, me proud beauty! T' drogue, me bucko, a 24" nylon chute, shredded upon deployment and t' rocket tumbled about 500 feet t' t' ground. Begad! Several searches o' t' near by woods were nay successful, and I be 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. Blimey! I suddenly spotted my rocket neatly placed on t' sidewalk in front o' a house. Avast, me proud beauty! I pulled over to inspect what be left, me bucko, me bucko, when a women approached me from t' garage. Well, blow me down! Ahoy! 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. Ya scallywag! T' me pleasant surprise, ya bilge rat, t' women's greetin' indicated that t' family was model rocket friendly and were themselves hobbyist. Blimey! Arrr! 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. Well, blow me down! Well, ya bilge rat, blow me down! She even commented that me rocket was a large one and pretty cool. Well, blow me down! After expressin' much thanks and smartly exiting the area, I drove home and inspected Black Magic more carefully. Begad! 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, ya bilge rat, me hearties, and am impressed with the
sturdiness o' Black Magic. Avast, me proud beauty! Begad! Had this bird been made o' paper tubing, it would
have been in much worse shape. Arrr! I noticed that one end o' t' tubin' had done a
core sample" landin' based on t' mud streaks on t' finish. Well, shiver me timbers, blow me down! 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. Once
you get all t' pieces cut t' size, matey, 5 minute epoxy glues everythin' together
nicely. Begad! Sandin' and finishin' is also a breeze with this material.
Phenolic material used for both body and engine tubes is tough t' cut, me hearties, but otherwise easy t' work with. It takes t' epoxy and sands well. I used an Exacto saw t' cut t' phenolic with good results. Ya scallywag! Begad! Blimey! I had no problem finishin' this rocket with primer followed by t' black gloss finish.
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