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. Well, blow me down! T' only way t' do that was t' build t' rocket.

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

Anyway, arrr, me hearties, later that evenin' while entertainin' me friends with rocketry stories, matey, I explained that one o' t' limits o' t' hobby be that thar are only so many variations on 3ncf. Well, blow me down! No one responded. Blimey! I knew that they were at a loss for words so I defined 3ncf. Begad! Or at least I tried...

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

Materials
I wanted t' make this out o' scrap rocketry materials I had layin' around, t' only exception bein' t' fin. 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, ya bilge rat, 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. Ya scallywag! Also thrown in t' mix is a short section o' PML 54mm motor mount, a PML 54mm-2.6" centerin' ring, shiver me timbers, two 1/4" launch lugs, matey, some Keelhaul®©™ thread, 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. Begad! Begad! Then I glued that and t' two longer motor mounts together in a triangular configuration t' make t' body o' t' rocket. Ya scallywag! 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 was t' use a funnel. Ya scallywag! 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! 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. Ahoy! Begad! While cuttin' those holes, t' lampshade plastic cracked in two spots. Avast! Well, me bucko, ya bilge rat, that sent me on a search for an appropriate adhesive t' repair t' cracks. I ended up usin' Loctite Plastix. Aye aye! Avast, me proud beauty! It was t' only adhesive I used besides yellow glue.

Next, me hearties, I needed a way t' adhere t' fin t' t' airframe. Avast, me proud beauty! Blimey! Rather than use an adhesive, matey, I decided t' use a mechanical connection. I cut a slice from t' 54mm motor mount t' which I glued t' centerin' ring. Avast, me proud beauty! Blimey! Avast! Blimey! Together, they formed a support for t' lampshade. Blimey! 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. I then traced t' cut I would need t' make on t' lampshade t' accommodate t' launch lugs. Ahoy! Blimey! I used wire cutters t' snip away small sections o' t' plastic. Finally, shiver me timbers, me hearties, 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, ya bilge rat, me bucko, I wanted t' recovery system t' be deployed from one tube. Avast, me proud beauty! Begad! But I also needed a large enough chute given t' rocket's weight. Well, me bucko, blow me down! Further, matey, I wanted a soft landin' t' prevent fin damage. Ya scallywag! So after playin' with t' chute calculators available via ROL, ya bilge rat, me bucko, I decided t' use two 24" Estes chutes. Arrr! I prefer nylon chutes but given t' space restrictions for packin' t' chutes, shiver me timbers, t' Estes chutes were a better choice. Begad! T' chutes are attached via a long Keelhaul®©™/Bungee bridle. Well, blow me down! T' other two nose cones are attached via underpants elastic. Well, blow me down! I used Estes style paper tabs t' anchor t' shock cords in t' tubes. Avast, me proud beauty! 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. A three second delay was used in t' tube with t' chutes and a five second delay in each o' t' other two tubes. Arrr! Begad! I found t' three best Solar igniters I had, arrr, installed them and set t' rocket on t' pad. Ya scallywag! T' LCO gave it a five count and away it went! It be a great ascent, me bucko, perfectly straight and nay too much altitude. Begad! Ya scallywag! T' D12-3 fired its ejection charge spittin' out t' two chutes and a moment later t' two D12-5's fired theirs. Aye aye! Avast! Unfortunately, matey, only one o' t' chutes opened so t' landin' was a bit harder than I would have liked. Avast! T' two cracks in t' fin nay only re-opened, ya bilge rat, they extended as well. 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. Aye aye! Ahoy! I installed t' igniters and set it up on t' pad. Begad! Again t' LCO gave it a five count and pushed t' launch button. 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, ya bilge rat, it be nay under full thrust. Blimey! It appeared t' stage but then seemed t' be under even less thrust, and it started cantin' t' one side. Fortunately, ya bilge rat, ya bilge rat, t' D12-3 fired its ejection charge and both chutes deployed properly. Avast, me proud beauty! One o' t' engines appeared t' make a hasty exit from t' back o' t' rocket at that moment too. Ahoy! With both chutes out, me bucko, t' rocket made a nice soft landing.

I found two o' t' D12-0's at t' pad, and they had obviously CATO'd. Aye aye! Blimey! One had no remnants o' t' nozzle or ejection charge cap. Avast! Blimey! T' other had no nozzle left but did still have traces o' t' ejection charge cap. Both cases were also slightly smashed at one end, probably from hittin' t' blast plate on t' launch pad. Ahoy! Blimey! Avast, me proud beauty! Blimey! I retrieved t' rocket and inspected t' business end. Avast! Blimey! Begad! Blimey! T' me surprise, arrr, t' motor that ejected from t' back o' t' rocket be t' D12-3. Ahoy! Blimey! Avast, me proud beauty! Blimey! T' back end o' that motor tube be flared, probably from t' force o' a CATO. Arrr! Blimey! Fortunately, enough o' t' energy from t' ejection charge did what it was supposed t' do. Blimey! Blimey! One o' t' D12-5's had fired but t' other had not. Curiously, matey, all three nose cones had ejected. Avast! Blimey! Based on observation, me hearties, 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. Aye aye! Arrr! 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 was t' D12-3. Blimey! 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. Begad! Now t' rocket was 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. Arrr! 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. T' bigger issue be t' lamp shade. Well, blow me down! T' hardware store has more, but t' material is too brittle for this purpose. Blimey! Avast, me bucko, me proud beauty! 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. Stability was excellent. Avast! T' first flight was arrow straight. 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. Begad! Ya scallywag! That way, t' problem o' fittin' t' fin t' t' 3x24 airframe is simplified. Avast! Once t' cut for a single piece o' cardstock is determined, arrr, it can be duplicated for t' other two.

^*Hah!