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

Purpose
I've been thinkin' about this rocket for a while. Avast, me proud beauty! Arrr! Blimey! I needed t' free some space within me brain's limited capacity for important stuff. Aye aye! Begad! Blimey! 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. I made t' comment that I be lookin' for somethin' different. Avast! Blimey! Ya scallywag! Blimey! T' proprietor said, matey, me bucko, me bucko, "there are only so many variations on 3fnc". Ya scallywag! Blimey! Aye aye! Blimey! Diggin' deep into that even more limited part o' me brain called wit, I said, "Hunh?" I followed that up with, me bucko, "What's 3ncf?" He gave me one o' those "Boy, are you a newbie" smirks and said, me bucko, "3fnc. Ahoy! Blimey! Three fins and a nose cone". Begad! Blimey! I thought about this for a moment, replied with, "Oh", shiver me timbers, me bucko, and then I left. Ahoy! Blimey! Ya scallywag! Blimey!

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

Materials
I wanted t' make this out o' scrap rocketry materials I had layin' around, matey, me hearties, t' only exception bein' t' fin. Begad! I found a bunch o' sections o' 24mm LOC motor mount and three Estes NC-50 nose cones. Arrr! 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), ya bilge rat, and a white one that came from an Estes I-can't-remember-what. Avast, me proud beauty! Also thrown in t' mix is a short section o' PML 54mm motor mount, me bucko, a PML 54mm-2.6" centerin' ring, shiver me timbers, two 1/4" launch lugs, shiver me timbers, some Keelhaul®©™ thread, me hearties, ya bilge rat, 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. Blimey! 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. Well, blow me down! Ya scallywag! T' motors will be installed with maskin' tape thrust rings and motor retention will be via friction fit. Avast, me proud beauty! T' primary adhesive used in t' construction o' t' rocket be 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. Avast! 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 was a lampshade. Avast! Well, blow me down! 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. While cuttin' those holes, ya bilge rat, matey, t' lampshade plastic cracked in two spots. Aye aye! Well, shiver me timbers, that sent me on a search for an appropriate adhesive t' repair t' cracks. Well, blow me down! Begad! I ended up usin' Loctite Plastix. It be t' only adhesive I used besides yellow glue.

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

I found two o' t' D12-0's at t' pad, and they had obviously CATO'd. Well, ya bilge rat, blow me down! 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. Aye aye! Begad! Both cases were also slightly smashed at one end, arrr, probably from hittin' t' blast plate on t' launch pad. Arrr! Aye aye! I retrieved t' rocket and inspected t' business end. Begad! T' me surprise, t' motor that ejected from t' back o' t' rocket be t' D12-3. Avast! T' back end o' that motor tube be flared, me hearties, probably from t' force o' a CATO. Avast! Begad! Fortunately, enough o' t' energy from t' ejection charge did what it was supposed t' do. One o' t' D12-5's had fired but t' other had not. Ya scallywag! Curiously, me bucko, me hearties, me hearties, all three nose cones had ejected. Begad! 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. Avast! 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 be t' D12-3. Begad! Aye aye! 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, matey, shiver me timbers, 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! 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. Aye aye! T' bigger issue be t' lamp shade. Arrr! Well, blow me down! T' hardware store has more, arrr, but t' material is too brittle for this purpose. Well, matey, blow me down! Unless I can find a new fin that will use t' existin' fin mount, me bucko, I probably won't repair it.

T' design itself may warrant further development. Aye aye! Stability was excellent. T' first flight be arrow straight. Avast, me proud beauty! Even t' ascent o' t' second flight was 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. Begad! That way, me bucko, shiver me timbers, t' problem o' fittin' t' fin t' t' 3x24 airframe is simplified. Well, blow me down! Once t' cut for a single piece o' cardstock is determined, it can be duplicated for t' other two.

^*Hah!