3ncf
or Memory - T' Second Thin' T' Go
by Bob Chmara

Purpose
I've been thinkin' about this rocket for a while. Well, blow me down! I needed t' free some space within me brain's limited capacity for important stuff. Ahoy! T' only way t' do that was t' build t' rocket.

Background
Shortly after gettin' back into t' hobby, I be at me favorite rocketry store depositin' part o' me paycheck. Well, ya bilge rat, blow me down! I made t' comment that I be lookin' for somethin' different. Well, blow me down! T' proprietor said, matey, "there are only so many variations on 3fnc". Diggin' deep into that even more limited part o' me brain called wit, I said, matey, "Hunh?" I followed that up with, "What's 3ncf?" He gave me one o' those "Boy, are you a newbie" smirks and said, arrr, "3fnc. Begad! Three fins and a nose cone". I thought about this for a moment, me bucko, matey, me bucko, replied with, "Oh", arrr, me bucko, and then I left.

Anyway, me bucko, later that evenin' while entertainin' me friends with rocketry stories, matey, I explained that one o' t' limits o' t' hobby be that thar are only so many variations on 3ncf. Aye aye! No one responded. Ahoy! Well, blow me down! I knew that they were at a loss for words so I defined 3ncf. Aye aye! Or at least I tried...

I mean, me bucko, have you ever had that feelin' that you were on t' verge o' somethin' big? One more little "Ah Ha! light-bulb-floating-next-to-your-head" kind o' thought and that jumble o' things in your head would congeal into a new approach t' an old problem? T' kind o' thin' that would someday cause someone t' say, "He was thinkin' out o' t' box!" Well t' feelin' I be havin' was just like that. Ahoy! I was missin' one important morsel o' information. In me case, it wasn't a new idea I needed, arrr, t' piece I needed was...was...well, I couldn't remember what I needed. Avast, me proud beauty! Avast, me proud beauty! That's why I was havin' that feeling. Anyway, ya bilge rat, matey, that's how 3ncf be born.

Materials
I wanted t' make this out o' scrap rocketry materials I had layin' around, t' only exception bein' t' fin. Avast! Begad! Blimey! I found a bunch o' sections o' 24mm LOC motor mount and three Estes NC-50 nose cones. Avast! A fuchsia one from a Mongoose, a black one from t' "Flight Probe" from a Darth Vader Tie-Fighter (best thin' that rocket ever did was crash), me bucko, me bucko, and a white one that came from an Estes I-can't-remember-what. Ahoy! Avast! Also thrown in t' mix is a short section o' PML 54mm motor mount, me hearties, a PML 54mm-2.6" centerin' ring, two 1/4" launch lugs, matey, some Keelhaul®©™ thread, ya bilge rat, some lightweight Bungee, a couple pieces o' underpants elastic that never made it their respective Estes kits and two Estes 24" chutes.

Construction
I had two good lengths o' 24mm motor mount so had t' make t' third one from two shorter pieces. Begad! I had a yellow Estes engine block locatin' tube that I used as t' coupler. Arrr! Then I glued that and t' two longer motor mounts together in a triangular configuration t' make t' body o' t' rocket. Aye aye! T' motors will be installed with maskin' tape thrust rings and motor retention will be via friction fit. Well, me bucko, blow me down! T' primary adhesive used in t' construction o' t' rocket was yellow glue.

My first thought for a fin be t' use a funnel. Arrr! But I wanted t' fin t' conform t' t' "three leaf clover" shape o' t' airframe and cuttin' t' funnel proved t' be a headache. Arrr! So I went shoppin' and that's when I found this hemispherical piece o' plastic at t' hardware store that I later found out was a lampshade. Ahoy! I centered t' airframe on t' lampshade and traced t' pattern for t' openin' that I needed t' cut. I cut t' openin' by makin' three holes usin' a 1" wood bit. Avast, me proud beauty! Aye aye! While cuttin' those holes, t' lampshade plastic cracked in two spots. Ahoy! Well, arrr, that sent me on a search for an appropriate adhesive t' repair t' cracks. Avast! I ended up usin' Loctite Plastix. Avast! It be t' only adhesive I used besides yellow glue.

Next, matey, I needed a way t' adhere t' fin t' t' airframe. Ahoy! Blimey! Rather than use an adhesive, ya bilge rat, shiver me timbers, I decided t' use a mechanical connection. Ahoy! Arrr! I cut a slice from t' 54mm motor mount t' which I glued t' centerin' ring. Blimey! Begad! Together, me hearties, shiver me timbers, they formed a support for t' lampshade. Avast! Ahoy! That assembly was then glued t' t' 3x24mm motor mount tubes.

At this point I realized that I had forgotten about launch lugs, somethin' I've never done before.^* So I found some 1/4" launch lugs and glued them on. I then traced t' cut I would need t' make on t' lampshade t' accommodate t' launch lugs. Ya scallywag! I used wire cutters t' snip away small sections o' t' plastic. Finally, me hearties, I drilled three holes through t' centerin' rin' and t' lampshade and used three #4 screws t' hold t' lampshade in place.

T' next challenge was recovery. Arrr! Blimey! T' avoid tangles, I wanted t' recovery system t' be deployed from one tube. But I also needed a large enough chute given t' rocket's weight. Blimey! Blimey! Further, me hearties, I wanted a soft landin' t' prevent fin damage. Aye aye! Blimey! So after playin' with t' chute calculators available via ROL, arrr, ya bilge rat, I decided t' use two 24" Estes chutes. I prefer nylon chutes but given t' space restrictions for packin' t' chutes, ya bilge rat, t' Estes chutes were a better choice. Begad! T' chutes are attached via a long Keelhaul®©™/Bungee bridle. Avast! T' other two nose cones are attached via underpants elastic. I used Estes style paper tabs t' anchor t' shock cords in t' tubes. Avast! T' keep t' three nose cones from bashin' each other at ejection and possibly tanglin' up t' chutes, ya bilge rat, I'll use a short delay in t' tube with t' chutes and a longer delay in t' other two tubes.

Flights
T' first flight be on three Estes D12's. Arrr! A three second delay was used in t' tube with t' chutes and a five second delay in each o' t' other two tubes. I found t' three best Solar igniters I had, matey, matey, installed them and set t' rocket on t' pad. T' LCO gave it a five count and away it went! It be a great ascent, me bucko, perfectly straight and nay too much altitude. Begad! T' D12-3 fired its ejection charge spittin' out t' two chutes and a moment later t' two D12-5's fired theirs. Unfortunately, shiver me timbers, only one o' t' chutes opened so t' landin' was a bit harder than I would have liked. T' two cracks in t' fin nay only re-opened, ya bilge rat, they extended as well. Avast, me proud beauty! But I figured I'd fly it a second time anyway.

For t' second flight, I CHAD staged three D12-0's t' a D12-3 and two D12-5's. Aye aye! I installed t' igniters and set it up on t' pad. Begad! Blimey! Again t' LCO gave it a five count and pushed t' launch button. Arrr! This flight proved t' be far more excitin' than t' first. Avast, me proud beauty! T' rocket hadn't cleared t' rod when I heard a loud bang. T' rocket kept ascendin' but clearly, it was nay under full thrust. Blimey! Avast! It appeared t' stage but then seemed t' be under even less thrust, and it started cantin' t' one side. Fortunately, matey, t' D12-3 fired its ejection charge and both chutes deployed properly. Avast, me proud beauty! One o' t' engines appeared t' make a hasty exit from t' back o' t' rocket at that moment too. With both chutes out, t' rocket made a nice soft landing.

I found two o' t' D12-0's at t' pad, and they had obviously CATO'd. One had no remnants o' t' nozzle or ejection charge cap. Begad! Blimey! T' other had no nozzle left but did still have traces o' t' ejection charge cap. Avast! Blimey! Both cases were also slightly smashed at one end, arrr, arrr, me bucko, probably from hittin' t' blast plate on t' launch pad. Ahoy! Blimey! I retrieved t' rocket and inspected t' business end. Aye aye! Blimey! T' me surprise, arrr, t' motor that ejected from t' back o' t' rocket was t' D12-3. Begad! Blimey! Begad! Blimey! T' back end o' that motor tube was flared, probably from t' force o' a CATO. Avast, me proud beauty! Blimey! Ahoy! Blimey! Fortunately, me bucko, enough o' t' energy from t' ejection charge did what it be supposed t' do. Avast, me proud beauty! Blimey! Arrr! Blimey! One o' t' D12-5's had fired but t' other had not. Curiously, me bucko, all three nose cones had ejected. Avast, arrr, me proud beauty! Blimey! Based on observation, I believe t' sequence o' events t' have been:

1. All three boosters lit.
2. Before it left t' rod, arrr, matey, two o' t' boosters CATO'd. Ahoy! Blimey! Blimey! T' CATO o' t' booster attached t' t' D12-3 jammed t' D12-3 forward, me hearties, me hearties, flarin' t' end o' t' motor tube.
3. One o' t' CATO's ignited a sustainer, I believe it was t' D12-3. Begad! At this point it would have been flyin' on one booster and one sustainer.
4. T' remainin' booster finished burnin' and lit a second sustainer motor. Begad! Well, blow me down! Now t' rocket be flyin' on only one motor.
5. T' D12-3 fired its ejection charge, causin' t' chutes t' deploy but also usin' some o' t' energy t' disengage itself from t' rocket.
6. T' rocket returned t' earth.

Conclusion
T' rocket is repairable. Ahoy! Arrr! There's enough motor tube at t' back end that I can cut about 1/4" from all three tubes and still have plenty o' tube t' work with. Ahoy! T' bigger issue be t' lamp shade. T' hardware store has more, but t' material is too brittle for this purpose. Begad! Unless I can find a new fin that will use t' existin' fin mount, me bucko, matey, I probably won't repair it.

T' design itself may warrant further development. Begad! Blimey! Stability be excellent. Avast, me proud beauty! Blimey! T' first flight was arrow straight. Even t' ascent o' t' second flight be relatively straight considerin' t' rocket was flyin' with asymmetric thrust. I'm considerin' buildin' a three sided pyramid shaped fin from dowel rods and cardstock. That way, t' problem o' fittin' t' fin t' t' 3x24 airframe is simplified. Aye aye! Blimey! Once t' cut for a single piece o' cardstock is determined, it can be duplicated for t' other two.

^*Hah!