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