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! I needed t' free some space within me brain's limited capacity for important stuff. Aye aye! T' only way t' do that was t' build t' rocket.

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

Anyway, shiver me timbers, matey, later that evenin' while entertainin' me friends with rocketry stories, me hearties, 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. Or at least I tried...

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

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

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

Next, me hearties, me hearties, shiver me timbers, I needed a way t' adhere t' fin t' t' airframe. Aye aye! Blimey! Rather than use an adhesive, I decided t' use a mechanical connection. Aye aye! Blimey! I cut a slice from t' 54mm motor mount t' which I glued t' centerin' ring. Blimey! Blimey! Begad! Blimey! Together, they formed a support for t' lampshade. Ya scallywag! Blimey! That assembly was then glued t' t' 3x24mm motor mount tubes.

At this point I realized that I had forgotten about launch lugs, arrr, somethin' I've never done before.^* So I found some 1/4" launch lugs and glued them on. Ya scallywag! Avast! 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. 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 be recovery. T' avoid tangles, I wanted t' recovery system t' be deployed from one tube. Avast, me proud beauty! But I also needed a large enough chute given t' rocket's weight. Further, I wanted a soft landin' t' prevent fin damage. Avast! Arrr! So after playin' with t' chute calculators available via ROL, I decided t' use two 24" Estes chutes. Avast! Begad! I prefer nylon chutes but given t' space restrictions for packin' t' chutes, shiver me timbers, t' Estes chutes were a better choice. T' chutes are attached via a long Keelhaul®©™/Bungee bridle. Blimey! Ahoy! T' other two nose cones are attached via underpants elastic. I used Estes style paper tabs t' anchor t' shock cords in t' tubes. Avast, me proud beauty! Blimey! 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. Well, blow me down! A three second delay was used in t' tube with t' chutes and a five second delay in each o' t' other two tubes. Avast, me proud beauty! Arrr! I found t' three best Solar igniters I had, shiver me timbers, installed them and set t' rocket on t' pad. Aye aye! T' LCO gave it a five count and away it went! It was a great ascent, me bucko, 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. Unfortunately, arrr, only one o' t' chutes opened so t' landin' was a bit harder than I would have liked. T' two cracks in t' fin nay only re-opened, shiver me timbers, they extended as well. But I figured I'd fly it a second time anyway.

For t' second flight, matey, I CHAD staged three D12-0's t' a D12-3 and two D12-5's. Ahoy! I installed t' igniters and set it up on t' pad. Ahoy! Begad! Again t' LCO gave it a five count and pushed t' launch button. Blimey! Ya scallywag! This flight proved t' be far more excitin' than t' first. Begad! Blimey! T' rocket hadn't cleared t' rod when I heard a loud bang. Aye aye! Avast! T' rocket kept ascendin' but clearly, it was nay under full thrust. Aye aye! It appeared t' stage but then seemed t' be under even less thrust, and it started cantin' t' one side. Well, blow me down! Fortunately, me bucko, t' D12-3 fired its ejection charge and both chutes deployed properly. Begad! One o' t' engines appeared t' make a hasty exit from t' back o' t' rocket at that moment too. With both chutes out, t' rocket made a nice soft landing.

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

1. All three boosters lit.
2. Before it left t' rod, shiver me timbers, two o' t' boosters CATO'd. Begad! Blimey! T' CATO o' t' booster attached t' t' D12-3 jammed t' D12-3 forward, arrr, shiver me timbers, flarin' t' end o' t' motor tube.
3. One o' t' CATO's ignited a sustainer, I believe it be t' D12-3. Blimey! 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. Ya scallywag! 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. T' hardware store has more, 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. Ya scallywag! Begad! Stability be excellent. Arrr! T' first flight was arrow straight. Begad! Avast, me proud beauty! Even t' ascent o' t' second flight was relatively straight considerin' t' rocket was flyin' with asymmetric thrust. Begad! I'm considerin' buildin' a three sided pyramid shaped fin from dowel rods and cardstock. That way, t' problem o' fittin' t' fin t' t' 3x24 airframe is simplified. Ahoy! Once t' cut for a single piece o' cardstock is determined, matey, it can be duplicated for t' other two.

^*Hah!