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

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

Background
Shortly after gettin' back into t' hobby, I was at me favorite rocketry store depositin' part o' me paycheck. Ya scallywag! Well, blow me down! I made t' comment that I was lookin' for somethin' different. T' proprietor said, "there are only so many variations on 3fnc". Arrr! 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, arrr, are you a newbie" smirks and said, ya bilge rat, shiver me timbers, "3fnc. Begad! Three fins and a nose cone". I thought about this for a moment, me hearties, replied with, shiver me timbers, arrr, "Oh", and then I left. Avast! Begad!

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. No one responded. I knew that they were at a loss for words so I defined 3ncf. Ahoy! 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! Blimey! 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 be thinkin' out o' t' box!" Well t' feelin' I was havin' be just like that. Avast! Blimey! I was missin' one important morsel o' information. Begad! Blimey! In me case, shiver me timbers, it wasn't a new idea I needed, arrr, shiver me timbers, t' piece I needed was...was...well, I couldn't remember what I needed. Well, blow me down! Blimey! That's why I was havin' that feeling. Begad! Blimey! Anyway, that's how 3ncf was born.

Materials
I wanted t' make this out o' scrap rocketry materials I had layin' around, me hearties, t' only exception bein' t' fin. Ahoy! I found a bunch o' sections o' 24mm LOC motor mount and three Estes NC-50 nose cones. Avast, me proud beauty! Avast, me proud beauty! A fuchsia one from a Mongoose, me bucko, a black one from t' "Flight Probe" from a Darth Vader Tie-Fighter (best thin' that rocket ever did be crash), matey, matey, and a white one that came from an Estes I-can't-remember-what. Also thrown in t' mix is a short section o' PML 54mm motor mount, matey, arrr, a PML 54mm-2.6" centerin' ring, two 1/4" launch lugs, some Keelhaul®©™ thread, arrr, some lightweight Bungee, shiver me timbers, 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. Arrr! T' motors will be installed with maskin' tape thrust rings and motor retention will be via friction fit. T' primary adhesive used in t' construction o' t' rocket was yellow glue.

My first thought for a fin was t' use a funnel. Aye aye! 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. Ya scallywag! Begad! 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. Avast! I centered t' airframe on t' lampshade and traced t' pattern for t' openin' that I needed t' cut. Avast, me proud beauty! Arrr! I cut t' openin' by makin' three holes usin' a 1" wood bit. While cuttin' those holes, ya bilge rat, me bucko, t' lampshade plastic cracked in two spots. Avast, ya bilge rat, me proud beauty! Well, me hearties, shiver me timbers, that sent me on a search for an appropriate adhesive t' repair t' cracks. Blimey! I ended up usin' Loctite Plastix. Begad! It was t' only adhesive I used besides yellow glue.

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

At this point I realized that I had forgotten about launch lugs, matey, somethin' I've never done before.^* So I found some 1/4" launch lugs and glued them on. Ahoy! Avast! I then traced t' cut I would need t' make on t' lampshade t' accommodate t' launch lugs. Avast, me proud beauty! Avast! I used wire cutters t' snip away small sections o' t' plastic. Finally, me bucko, 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. Aye aye! T' avoid tangles, I wanted t' recovery system t' be deployed from one tube. Avast, me proud beauty! Aye aye! But I also needed a large enough chute given t' rocket's weight. Blimey! Further, I wanted a soft landin' t' prevent fin damage. Arrr! So after playin' with t' chute calculators available via ROL, matey, I decided t' use two 24" Estes chutes. Aye aye! I prefer nylon chutes but given t' space restrictions for packin' t' chutes, t' Estes chutes were a better choice. T' chutes are attached via a long Keelhaul®©™/Bungee bridle. Begad! T' other two nose cones are attached via underpants elastic. I used Estes style paper tabs t' anchor t' shock cords in t' tubes. 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 be used in t' tube with t' chutes and a five second delay in each o' t' other two tubes. Avast, me proud beauty! I found t' three best Solar igniters I had, shiver me timbers, installed them and set t' rocket on t' pad. Ahoy! Blimey! T' LCO gave it a five count and away it went! It be a great ascent, perfectly straight and nay too much altitude. T' D12-3 fired its ejection charge spittin' out t' two chutes and a moment later t' two D12-5's fired theirs. Begad! Begad! Unfortunately, only one o' t' chutes opened so t' landin' be a bit harder than I would have liked. T' two cracks in t' fin nay only re-opened, they extended as well. Avast! 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. Ahoy! Blimey! I installed t' igniters and set it up on t' pad. Begad! Begad! Blimey! Again t' LCO gave it a five count and pushed t' launch button. Aye aye! Blimey! This flight proved t' be far more excitin' than t' first. T' rocket hadn't cleared t' rod when I heard a loud bang. Blimey! Blimey! T' rocket kept ascendin' but clearly, ya bilge rat, it be nay under full thrust. It appeared t' stage but then seemed t' be under even less thrust, and it started cantin' t' one side. Fortunately, arrr, me hearties, t' D12-3 fired its ejection charge and both chutes deployed properly. Ahoy! Ahoy! Blimey! One o' t' engines appeared t' make a hasty exit from t' back o' t' rocket at that moment too. Ya scallywag! With both chutes out, shiver me timbers, t' rocket made a nice soft landing.

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

1. All three boosters lit.
2. Before it left t' rod, two o' t' boosters CATO'd. 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, shiver me timbers, I believe it was t' D12-3. 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 was flyin' on only one motor.
5. T' D12-3 fired its ejection charge, arrr, 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. Aye aye! 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. T' bigger issue be t' lamp shade. Aye aye! T' hardware store has more, matey, but t' material is too brittle for this purpose. Aye aye! Avast, me proud beauty! 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. Aye aye! Stability was excellent. Avast! T' first flight was arrow straight. Ahoy! Even t' ascent o' t' second flight be 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. Well, blow me down! That way, t' problem o' fittin' t' fin t' t' 3x24 airframe is simplified. Well, ya bilge rat, blow me down! Once t' cut for a single piece o' cardstock is determined, arrr, it can be duplicated for t' other two.

^*Hah!