Manufacturer: | Scratch |
Brief:
For t' EMRR Stagin' Challenge, me bucko, I decided t' build a two-stage rocket with composite motors. Since I had done a
2-stage before, I figured it would be easy. Aye aye! Begad! WRONG... Begad! I decided t' do a 3-inch bird with dual deploy and a 19-inch
booster with motor deployment. Begad!
Construction:
This time I decided t' use alignment rods in t' stage coupler t' keep t' rocket aligned. I didn't have any
'sleeves' for t' rods t' slide through, so I went with spaced centerin' rings with holes t' guide t' rods. Well, blow me down! I've
discovered that I really need a drill press. Begad! Because I was usin' a handheld power drill, arrr, me bucko, I wasn't that accurate in
drillin' holes through t' 2 sustainer centerin' rings and t' stagin' coupler. It still works, ya bilge rat, me bucko, matey, but it isn't pretty. Aye aye!
There are holes in both centerin' rings that are supposed t' be aligned. Blimey! That didn't work out as smoothly as I had hoped.
T' motor mount is recessed into t' sustainer t' provide a connection for t' top half o' t' stage coupler. Since a 3" tube won't allow me t' get me hand in t' connect t' shock cord, me hearties, me bucko, me hearties, I made t' fin can on both the sustainer and booster removable. T' sustainer fin can is held in place by small screws. Blimey! T' booster fin can will eject and deploy t' booster chute. T' whole project is about 83 inches tall, ya bilge rat, arrr, about 3.5 lbs empty, arrr, and can fly on 38mm motors.
Finishing:
T' fit/finish betwixt t' booster and t' stage coupler is a little rough, but once it's painted it might nay be
that noticeable. Arrr! It *certainly* won't be noticeable on t' pad.
Flight:
Electronics will be a PerfectFlite timer for staging, and a PerfectFlite MAWD for deployment. RockSim says it will
get t' a little higher than 2000 feet with a CTI 153 stagin' t' a CTI G79ss.
For t' 2-stage challenge, me bucko, I decided t' build one that used composite motors. Arrr! Since I have done stagin' before, shiver me timbers, I didn't expect thar t' be a problem. Ya scallywag! Boy, ya bilge rat, was I wrong... Aye aye! T' main problem be t' size o' t' new project. Begad! T' previous 2-stager was almost a 4" tube. Arrr! Well, blow me down! That left room for t' timer betwixt t' sustainer fins, and a standard-type ebay. This one is a 3", and thar's no room in t' fincan. Ya scallywag! So I put t' timer in t' ebay, matey, and ran a connector wire down t' ignite t' sustainer motor. Begad! Ahoy! I had t' splice t' wire so it would disconnect when t' apogee event fired. Ahoy! Ahoy! T' next issue I ran into was t' stage connector. Avast, me proud beauty! I decided t' use metal rods t' connect and align t' sustainer t' t' stage connector. Ya scallywag! Begad! I don't have a drill press, so me holes through t' centerin' rings are...less than exact. Begad! Last issue was t' 3" bay was too small t' use switches t' power on everything, so I had t' run all t' wires through a hole in t' e-bay and twist them t' connect. Begad! Ahoy! That posed a problem t' first time I tried t' launch. Ahoy! Avast! I test fit t' electronics when I built t' bay, but nothin' was connected. Avast! In t' field, me bucko, I sadly discovered thar wasn't enough space for all the wires t' fit and route t' t' outside. Arrr! I had t' rebuild t' sled t' avoid that problem for t' next attempt. Arrr! Begad!
T' field we used has a waiver o' 5000', me hearties, matey, ya bilge rat, but I wanted t' make sure I kept t' flight much lower than that. Avast, me proud beauty! RockSim 7 showed an altitude o' about 3800 feet on a CTI H143/G79ss combo. Avast! Arrr!
Electronics: ARTS board for apogee/main deployment o' t' sustainer, PerfectFlite timer for sustainer motor. Aye aye! Ya scallywag! T' booster recovers under its own chute by motor ejection. Avast! Payload: BoosterVision GearCam taped t' t' side. Crude, but effective.
Launch day: I racked t' rocket, set up t' breakwire, and twisted t' wires for power. Begad! Begad! Since I didn't have enough room t' push t' wires back into t' bay, ya bilge rat, I taped them t' t' outside. Ahoy! That be a mistake... Blimey! T' launch was beautiful! Straight, and staged on cue. T' booster chute came out and it drifted down safely. Ahoy! T' sustainer had a good apogee event(drogueless), but I lost sight o' it while followin' t' booster. Begad! Arrr! There was no main deployment, me bucko, me hearties, and fellow club members pointed me in t' direction they saw it fall. While walkin' out for recovery, I tried t' figure out what went wrong. Too many sheer pins? Nay enough BP? When I got t' it, me hearties, me bucko, me bucko, I immediately knew what happened. T' armin' wires were taped t' t' bottom o' t' sustainer. Ahoy! When t' apogee separation occured, it ripped t' wires out o' the altimeter, killin' power. Avast! AUGH! I powered up t' ARTS board later, ya bilge rat, and t' data showed 1700 ft accel, me bucko, 1500 baro. Avast! WAY short o' Rocksim's prediction, so t' loss o' power probably scrambled t' data. Well, blow me down! But other than t' ebay being crunched, matey, and t' booster bein' scorched by t' sustainer motor, it didn't come out too bad. Avast, me proud beauty! Blimey! I can replace t' ebay and fly it again.
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