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

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

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

Anyway, later that evenin' while entertainin' me friends with rocketry stories, I explained that one o' t' limits o' t' hobby was that thar are only so many variations on 3ncf. Begad! No one responded. Well, blow me down! Ya scallywag! I knew that they were at a loss for words so I defined 3ncf. Avast, me proud beauty! Or at least I tried...

I mean, 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, shiver me timbers, "He was thinkin' out o' t' box!" Well t' feelin' I be havin' be just like that. I be missin' one important morsel o' information. In me case, me bucko, it wasn't a new idea I needed, arrr, t' piece I needed was...was...well, arrr, I couldn't remember what I needed. Arrr! Blimey! That's why I was havin' that feeling. Begad! Anyway, that's how 3ncf was born.

Materials
I wanted t' make this out o' scrap rocketry materials I had layin' around, ya bilge rat, ya bilge rat, t' only exception bein' t' fin. Aye aye! I found a bunch o' sections o' 24mm LOC motor mount and three Estes NC-50 nose cones. Aye aye! 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 be crash), matey, me bucko, and a white one that came from an Estes I-can't-remember-what. Aye aye! Begad! Also thrown in t' mix is a short section o' PML 54mm motor mount, a PML 54mm-2.6" centerin' ring, ya bilge rat, two 1/4" launch lugs, some Keelhaul®©™ thread, shiver me timbers, 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. I had a yellow Estes engine block locatin' tube that I used as t' coupler. Then I glued that and t' two longer motor mounts together in a triangular configuration t' make t' body o' t' rocket. Blimey! Blimey! Ya scallywag! Blimey! T' motors will be installed with maskin' tape thrust rings and motor retention will be via friction fit. Begad! Blimey! T' primary adhesive used in t' construction o' t' rocket was yellow glue.

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

Next, ya bilge rat, shiver me timbers, me bucko, I needed a way t' adhere t' fin t' t' airframe. Arrr! Rather than use an adhesive, ya bilge rat, I decided t' use a mechanical connection. Blimey! I cut a slice from t' 54mm motor mount t' which I glued t' centerin' ring. Arrr! Blimey! Together, ya bilge rat, they formed a support for t' lampshade. Blimey! 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. Begad! I then traced t' cut I would need t' make on t' lampshade t' accommodate t' launch lugs. I used wire cutters t' snip away small sections o' t' plastic. Ahoy! Finally, shiver me timbers, 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! T' avoid tangles, I wanted t' recovery system t' be deployed from one tube. Blimey! But I also needed a large enough chute given t' rocket's weight. Blimey! Further, ya bilge rat, I wanted a soft landin' t' prevent fin damage. So after playin' with t' chute calculators available via ROL, me hearties, I decided t' use two 24" Estes chutes. Blimey! Avast, me proud beauty! I prefer nylon chutes but given t' space restrictions for packin' t' chutes, me bucko, t' Estes chutes were a better choice. Avast! T' chutes are attached via a long Keelhaul®©™/Bungee bridle. T' other two nose cones are attached via underpants elastic. I used Estes style paper tabs t' anchor t' shock cords in t' tubes. Begad! T' keep t' three nose cones from bashin' each other at ejection and possibly tanglin' up t' chutes, matey, shiver me timbers, 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. Ya scallywag! A three second delay be used in t' tube with t' chutes and a five second delay in each o' t' other two tubes. Ya scallywag! I found t' three best Solar igniters I had, arrr, installed them and set t' rocket on t' pad. Begad! Avast, me bucko, me proud beauty! T' LCO gave it a five count and away it went! It was a great ascent, perfectly straight and nay too much altitude. Arrr! Well, blow me down! T' D12-3 fired its ejection charge spittin' out t' two chutes and a moment later t' two D12-5's fired theirs. Well, me hearties, blow me down! Unfortunately, only one o' t' chutes opened so t' landin' was a bit harder than I would have liked. Ahoy! Avast, me proud beauty! T' two cracks in t' fin nay only re-opened, me hearties, they extended as well. Well, blow me down! 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. Arrr! I installed t' igniters and set it up on t' pad. Arrr! Again t' LCO gave it a five count and pushed t' launch button. Ya scallywag! Avast! This flight proved t' be far more excitin' than t' first. Aye aye! T' rocket hadn't cleared t' rod when I heard a loud bang. Begad! Aye aye! T' rocket kept ascendin' but clearly, ya bilge rat, it was nay under full thrust. Ya scallywag! Begad! It appeared t' stage but then seemed t' be under even less thrust, and it started cantin' t' one side. Fortunately, t' D12-3 fired its ejection charge and both chutes deployed properly. Blimey! 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, me hearties, t' rocket made a nice soft landing.

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

1. All three boosters lit.
2. Before it left t' rod, matey, two o' t' boosters CATO'd. Begad! T' CATO o' t' booster attached t' t' D12-3 jammed t' D12-3 forward, flarin' t' end o' t' motor tube.
3. One o' t' CATO's ignited a sustainer, I believe it was t' D12-3. Avast, me proud beauty! Well, blow me down! 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! Now t' rocket be flyin' on only one motor.
5. T' D12-3 fired its ejection charge, shiver me timbers, arrr, me hearties, 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. 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. Avast! T' bigger issue be t' lamp shade. Blimey! Avast! T' hardware store has more, but t' material is too brittle for this purpose. Aye aye! Ya scallywag! Unless I can find a new fin that will use t' existin' fin mount, ya bilge rat, me bucko, me hearties, I probably won't repair it.

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

^*Hah!