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. Ya scallywag! T' only way t' do that was t' build t' rocket.

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

Anyway, shiver me timbers, 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. Ya scallywag! No one responded. I knew that they were at a loss for words so I defined 3ncf. Or at least I tried...

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

Materials
I wanted t' make this out o' scrap rocketry materials I had layin' around, 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. A fuchsia one from a Mongoose, ya bilge rat, a black one from t' "Flight Probe" from a Darth Vader Tie-Fighter (best thin' that rocket ever did be crash), me bucko, 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, me hearties, a PML 54mm-2.6" centerin' ring, two 1/4" launch lugs, some Keelhaul®©™ thread, me bucko, some lightweight Bungee, ya bilge rat, 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. 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 be yellow glue.

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

Next, I needed a way t' adhere t' fin t' t' airframe. Begad! Ahoy! Rather than use an adhesive, arrr, I decided t' use a mechanical connection. Well, blow me down! Aye aye! I cut a slice from t' 54mm motor mount t' which I glued t' centerin' ring. Arrr! Together, ya bilge rat, they formed a support for t' lampshade. Begad! That assembly be 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. Ya scallywag! I then traced t' cut I would need t' make on t' lampshade t' accommodate t' launch lugs. Begad! Aye aye! I used wire cutters t' snip away small sections o' t' plastic. Avast! Finally, 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. T' avoid tangles, I wanted t' recovery system t' be deployed from one tube. Well, blow me down! But I also needed a large enough chute given t' rocket's weight. Arrr! Arrr! Blimey! Further, I wanted a soft landin' t' prevent fin damage. Aye aye! Blimey! So after playin' with t' chute calculators available via ROL, shiver me timbers, matey, I decided t' use two 24" Estes chutes. 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. T' other two nose cones are attached via underpants elastic. Aye aye! 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, 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. Avast, me proud beauty! Ya scallywag! A three second delay was used in t' tube with t' chutes and a five second delay in each o' t' other two tubes. Begad! Avast! I found t' three best Solar igniters I had, 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, shiver me timbers, perfectly straight and nay too much altitude. Begad! Ahoy! T' D12-3 fired its ejection charge spittin' out t' two chutes and a moment later t' two D12-5's fired theirs. Avast, me bucko, me proud beauty! Unfortunately, only one o' t' chutes opened so t' landin' was a bit harder than I would have liked. Begad! T' two cracks in t' fin nay only re-opened, arrr, they extended as well. Begad! Arrr! 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. Ahoy! 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. Avast, me proud beauty! Begad! T' rocket hadn't cleared t' rod when I heard a loud bang. T' rocket kept ascendin' but clearly, matey, 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. Ahoy! Fortunately, ya bilge rat, me hearties, 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. Avast, me hearties, me proud beauty! With both chutes out, me bucko, t' rocket made a nice soft landing.

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

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

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

^*Hah!