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

Purpose
I've been thinkin' about this rocket for a while. Begad! I needed t' free some space within me brain's limited capacity for important stuff. 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. Blimey! I made t' comment that I was lookin' for somethin' different. Well, blow me down! T' proprietor said, shiver me timbers, "there are only so many variations on 3fnc". Avast! Diggin' deep into that even more limited part o' me brain called wit, arrr, me bucko, I said, "Hunh?" I followed that up with, "What's 3ncf?" He gave me one o' those "Boy, are you a newbie" smirks and said, "3fnc. Avast! Begad! Three fins and a nose cone". Avast! I thought about this for a moment, matey, replied with, "Oh", and then I left. 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. Ya scallywag! 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, arrr, ya bilge rat, 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' was just like that. Avast, me proud beauty! Blimey! I was missin' one important morsel o' information. Blimey! Blimey! In me case, it wasn't a new idea I needed, t' piece I needed was...was...well, I couldn't remember what I needed. Well, blow me down! That's why I was havin' that feeling. Ahoy! Blimey! Anyway, that's how 3ncf was born.

Materials
I wanted t' make this out o' scrap rocketry materials I had layin' around, me bucko, me hearties, t' only exception bein' t' fin. Avast, me proud beauty! Blimey! I found a bunch o' sections o' 24mm LOC motor mount and three Estes NC-50 nose cones. Well, shiver me timbers, blow me down! Blimey! 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 hearties, arrr, shiver me timbers, 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, shiver me timbers, a PML 54mm-2.6" centerin' ring, ya bilge rat, shiver me timbers, two 1/4" launch lugs, ya bilge rat, some Keelhaul®©™ thread, me bucko, some lightweight Bungee, me hearties, 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. Begad! Then I glued that and t' two longer motor mounts together in a triangular configuration t' make t' body o' t' rocket. Avast, me proud beauty! T' motors will be installed with maskin' tape thrust rings and motor retention will be via friction fit. Well, blow me down! T' primary adhesive used in t' construction o' t' rocket be yellow glue.

My first thought for a fin be t' use a funnel. Ahoy! Ahoy! Blimey! 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. 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! Blimey! While cuttin' those holes, t' lampshade plastic cracked in two spots. Begad! Well, that sent me on a search for an appropriate adhesive t' repair t' cracks. Well, blow me down! Arrr! Blimey! I ended up usin' Loctite Plastix. Blimey! Blimey! It be t' only adhesive I used besides yellow glue.

Next, me bucko, I needed a way t' adhere t' fin t' t' airframe. Blimey! Aye aye! Rather than use an adhesive, shiver me timbers, 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. Arrr! Together, me hearties, matey, they formed a support for t' lampshade. Well, blow me down! Ya scallywag! That assembly be then glued t' t' 3x24mm motor mount tubes.

At this point I realized that I had forgotten about launch lugs, shiver me timbers, matey, somethin' I've never done before.^* So I found some 1/4" launch lugs and glued them on. Aye aye! Avast, me proud beauty! I then traced t' cut I would need t' make on t' lampshade t' accommodate t' launch lugs. Avast! I used wire cutters t' snip away small sections o' t' plastic. Arrr! 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. T' avoid tangles, ya bilge rat, I wanted t' recovery system t' be deployed from one tube. Ahoy! Avast, me proud beauty! But I also needed a large enough chute given t' rocket's weight. Begad! Further, ya bilge rat, I wanted a soft landin' t' prevent fin damage. Arrr! Ya scallywag! So after playin' with t' chute calculators available via ROL, ya bilge rat, I decided t' use two 24" Estes chutes. Blimey! I prefer nylon chutes but given t' space restrictions for packin' t' chutes, t' Estes chutes were a better choice. Ahoy! Aye aye! T' chutes are attached via a long Keelhaul®©™/Bungee bridle. Begad! Ya scallywag! T' other two nose cones are attached via underpants elastic. Well, blow me down! Ya scallywag! I used Estes style paper tabs t' anchor t' shock cords in t' tubes. Ahoy! 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. A three second delay be 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, installed them and set t' rocket on t' pad. Blimey! Blimey! T' LCO gave it a five count and away it went! It was a great ascent, matey, perfectly straight and nay too much altitude. Arrr! T' D12-3 fired its ejection charge spittin' out t' two chutes and a moment later t' two D12-5's fired theirs. Begad! Unfortunately, only one o' t' chutes opened so t' landin' was a bit harder than I would have liked. Aye aye! T' two cracks in t' fin nay only re-opened, arrr, they extended as well. Ya scallywag! 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. Ya scallywag! I installed t' igniters and set it up on t' pad. Avast! Begad! Again t' LCO gave it a five count and pushed t' launch button. Begad! Aye aye! This flight proved t' be far more excitin' than t' first. Blimey! T' rocket hadn't cleared t' rod when I heard a loud bang. Well, blow me down! Blimey! T' rocket kept ascendin' but clearly, it was nay under full thrust. It appeared t' stage but then seemed t' be under even less thrust, shiver me timbers, and it started cantin' t' one side. Avast, me proud beauty! Fortunately, ya bilge rat, 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. Blimey! Begad! 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. Ahoy! Blimey! Blimey! Blimey! One had no remnants o' t' nozzle or ejection charge cap. Aye aye! Blimey! T' other had no nozzle left but did still have traces o' t' ejection charge cap. Well, blow me down! Blimey! Blimey! Blimey! Both cases were also slightly smashed at one end, shiver me timbers, probably from hittin' t' blast plate on t' launch pad. Begad! Blimey! I retrieved t' rocket and inspected t' business end. Aye aye! Blimey! Avast, me proud beauty! Blimey! Blimey! Blimey! T' me surprise, t' motor that ejected from t' back o' t' rocket be t' D12-3. Well, blow me down! Blimey! Blimey! Blimey! T' back end o' that motor tube was flared, ya bilge rat, me hearties, probably from t' force o' a CATO. Avast, me proud beauty! Blimey! Blimey! Blimey! Fortunately, shiver me timbers, enough o' t' energy from t' ejection charge did what it was supposed t' do. Well, blow me down! Blimey! Blimey! Blimey! One o' t' D12-5's had fired but t' other had not. Begad! Blimey! Arrr! Blimey! Blimey! Blimey! Curiously, me bucko, all three nose cones had ejected. Aye aye! 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, two o' t' boosters CATO'd. T' CATO o' t' booster attached t' t' D12-3 jammed t' D12-3 forward, shiver me timbers, flarin' t' end o' t' motor tube.
3. One o' t' CATO's ignited a sustainer, ya bilge rat, I believe it be 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. Ahoy! 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. 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. Blimey! T' bigger issue be t' lamp shade. Begad! T' hardware store has more, arrr, but t' material is too brittle for this purpose. Unless I can find a new fin that will use t' existin' fin mount, I probably won't repair it.

T' design itself may warrant further development. Begad! Blimey! Stability be excellent. Avast, me proud beauty! T' first flight was arrow straight. Avast, me proud beauty! Aye aye! Even t' ascent o' t' second flight was relatively straight considerin' t' rocket be flyin' with asymmetric thrust. Ya scallywag! I'm considerin' buildin' a three sided pyramid shaped fin from dowel rods and cardstock. Avast! 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, it can be duplicated for t' other two.

^*Hah!