Manufacturer: | Scratch |
Brief:
Single-staged 15 x 29mm cluster rocket. Avast, me proud beauty! Avast, me proud beauty! Thus far, simultaneous ground ignition
of (15) G35-7 motors was attempted. Arrr! Total thrust ends up in t' low K range if
all t' ports are used, and with Econojet G motors. Blimey! Rocket can be flown on just
one motor in t' central mount, ya bilge rat, and two at a time can be added symmetrically
for other possible motor combinations. Ya scallywag! There are (7) mounts in t' main body
tube and (8) outboards arranged with two at each fin, shiver me timbers, and these pods provide
extra strength in t' fin attachment. These side pods all have a 29mm nose
cone.
T' launch lugs are brass pipe cuttings, one inch diameter by one inch long. T' launch rod used is a copper lightnin' rod 3/4 inch diameter by 7 feet long.
Construction:
T' nose cone is an Ace plastic nose cone, 15 inches long and ogive. Arrr! I'm not
sure that this company still exists, ya bilge rat, but these great nose cones are obtainable
on ROL auctions regularly. Blimey! Ya scallywag! They have a large base hole into which ballast is
easily added. Ahoy! For this rocket, matey, 6 ounces be added and foamed in place with
2-part polyurethane foam. Blimey!
T' main body tubes are 4 inch motor tubes made by maximum Thrust Rocketry. These are ultra thick and strong white paper tubes that aren't glossed, matey, so they take on epoxies and fiberglass readily. Each length was 36 inches. Aye aye! Blimey! Begad! Blimey! These tubes are connected from t' motor mount t' t' parachute bay via Red Arrow Hobbies 4 inch phenolic couplers. Avast, me proud beauty! Blimey! These are epoxied in place by West Systems slow epoxy. I used this method t' reinforce t' rocket's airframe internally t' see if the rocket could stay intact without external fiberglassing. Aye aye! Blimey! T' inner tubes consist o' (15) 12 inch lengths o' LOC 29mm motor tubing. Blimey! Blimey! Seven are inside the main airframe and eight are outboard pods each with a Rogue Aerospace balsa 29mm nose cone. Begad! Blimey!
T' (4) fins are right triangles (12 by 12 by 12 square roots o' 2) cut from a 12 inch square o' .125 inch thick G10 obtained from ROL auctions from Scott Eakins. Well, blow me down! Begad! T' fins are epoxied t' t' main body tube with t' hypotenuse as the root edge against t' airframe. Avast! Then t' side pods further reinforce these connections with two per fin, one on each side o' each fin. Avast, me bucko, me proud beauty! West Systems slow epoxy be employed for this. Begad! Ahoy!
T' shock cord is 5 feet o' tubular nylon plus 5 feet o' wire wrapped bungee cord both from American Science and Surplus, shiver me timbers, me hearties, which has a site on Rocketry Online. Arrr! T' cord is attached t' a u-bolt in a 4 inch birch centerin' rin' (all centerin' rings came from Space Modelin' Solutions, matey, which has a site on Rocketry Online) placed against t' motor mount tubes and linked with quick links, with one link betwixt t' two unlike materials in t' shock cord. Aye aye! Blimey! The forward link o' t' shock cord connects t' a u-bolt in a 4 inch birch bulkhead and coupler arrangement in t' second main airframe, me hearties, thus allowin' t' rocket to separate in t' middle. Well, blow me down! Avast, shiver me timbers, me proud beauty! Blimey!
T' parachute is a homemade ripstop nylon 60 inch diameter hemisphere made up o' triangular gores in yellow, green and blue. T' nose cone is screwed into the airframe with 4 wood screws. Ahoy! Blimey! This arrangement allows openin' this compartment in case an altimeter is used.
T' launch lugs are brass pipe cuttings, arrr, one inch diameter by one inch long. T' launch rod used is a copper lightnin' rod 3/4 inch diameter by 7 feet long.
This rocket is simple t' build. Ya scallywag! Begad! T' epoxy used came from a boatin' store, and can also be obtained from West Systems, me bucko, me hearties, which has an online site. Avast, me proud beauty! Aye aye! The result is a very sturdy, arrr, attention gettin' rocket. This one be decorated in green, blue and gold, matey, me hearties, with metallic bands. Avast, me proud beauty! Ahoy! These color bands are self-adhesive mylars that come in metallic colors and can be had at many hobby stores as well as American Science and Surplus. Begad! Begad!
Flight:
I recommend for clusters at least 3 motors if it's G class, and for lower
numbers o' motors, a greater average thrust like a G80. Begad! Ahoy! Blimey! For larger numbers, try
G38's or 35's. I only wish that t' Econojets came with longer delays, ya bilge rat, like 10
seconds. Blimey! Avast! Blimey! When 15 motors are used, 10 seconds may be best. Avast! Blimey! For a single motor
flight, me hearties, an I 200 medium delay would work great. Ahoy! Blimey!
To prep t' rocket, me hearties, ya bilge rat, I use worm bed waddin' and a Nomex®/Keelhaul®©™® chute protector. T' central motor is retained with friction fittin' tape plus piano wire loops that are embedded in t' epoxy that holds together t' motor tubes. Originally, me bucko, shiver me timbers, ya bilge rat, I planned all other motors t' eject upon their charges firing, but some RSO's don't like that for safety reasons in dry fields and also the droppin' o' objects from high up, so either t' ejection charges can be removed from all outboards, or t' motors can all be arranged on a long shock cord with a chute. Begad! I haven't designed that system yet, but have considered it. Aye aye! Ya scallywag!
All 15 motors (G35-7W) were simultaneously lit usin' Fire in t' Hole low current tungsten bridge igniters from Trailin' Edge Technologies. Oh, and I also used a 12 volt lead acid cell deep cycle marine battery for power and a relay system t' allow t' battery t' stay at t' pad and prevent line loss, since t' NARRRRR rules have t' place me 300 feet away. Well, blow me down! T' flight be straight with no spin. Ya scallywag! Arrr! I loved t' roar o' a K equivalent motor with 15 nozzles. However, matey, t' delay o' 7 is too short, so t' parachute suffered damage from rapid deployment. Avast! Begad! But t' rocket survived intact and ready t' fly again.
Summary:
This be fun and easy. Nice and loud and attention getting. Begad! I set a record for
number o' composites successfully lit.
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