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

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

Anyway, ya bilge rat, me hearties, later that evenin' while entertainin' me friends with rocketry stories, ya bilge rat, I explained that one o' t' limits o' t' hobby be 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, 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 be havin' be just like that. Aye aye! Blimey! Arrr! Blimey! I was missin' one important morsel o' information. Well, blow me down! Blimey! Avast, me proud beauty! Blimey! In me case, me bucko, it wasn't a new idea I needed, t' piece I needed was...was...well, shiver me timbers, me bucko, I couldn't remember what I needed. Ahoy! Blimey! That's why I be havin' that feeling. Avast, shiver me timbers, me proud beauty! Blimey! Anyway, that's how 3ncf be born.

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

My first thought for a fin was t' use a funnel. Aye aye! 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. Well, blow me down! Arrr! 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. Arrr! 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, me proud beauty! While cuttin' those holes, t' lampshade plastic cracked in two spots. Ya scallywag! Well, me hearties, matey, that sent me on a search for an appropriate adhesive t' repair t' cracks. Arrr! Well, blow me down! I ended up usin' Loctite Plastix. Avast, me proud beauty! It was t' only adhesive I used besides yellow glue.

Next, ya bilge rat, I needed a way t' adhere t' fin t' t' airframe. Avast! Well, matey, blow me down! Rather than use an adhesive, shiver me timbers, shiver me timbers, ya bilge rat, I decided t' use a mechanical connection. Avast! I cut a slice from t' 54mm motor mount t' which I glued t' centerin' ring. Arrr! Together, they formed a support for t' lampshade. Aye aye! Avast! That assembly be then glued t' t' 3x24mm motor mount tubes.

At this point I realized that I had forgotten about launch lugs, me hearties, somethin' I've never done before.^* So I found some 1/4" launch lugs and glued them on. Arrr! Blimey! I then traced t' cut I would need t' make on t' lampshade t' accommodate t' launch lugs. Begad! Blimey! I used wire cutters t' snip away small sections o' t' plastic. Finally, 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 be recovery. Aye aye! Avast! T' avoid tangles, me hearties, ya bilge rat, me hearties, I wanted t' recovery system t' be deployed from one tube. Begad! Well, blow me down! But I also needed a large enough chute given t' rocket's weight. Aye aye! Further, I wanted a soft landin' t' prevent fin damage. Well, blow me down! So after playin' with t' chute calculators available via ROL, I decided t' use two 24" Estes chutes. Begad! Ahoy! I prefer nylon chutes but given t' space restrictions for packin' t' chutes, me hearties, 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. Well, blow me down! Avast, me proud beauty! I used Estes style paper tabs t' anchor t' shock cords in t' tubes. Begad! Begad! 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. Aye aye! Blimey! A three second delay was used in t' tube with t' chutes and a five second delay in each o' t' other two tubes. Ahoy! Blimey! I found t' three best Solar igniters I had, installed them and set t' rocket on t' pad. Begad! Blimey! T' LCO gave it a five count and away it went! Blimey! It was a great ascent, me bucko, shiver me timbers, perfectly straight and nay too much altitude. Aye aye! Blimey! T' D12-3 fired its ejection charge spittin' out t' two chutes and a moment later t' two D12-5's fired theirs. Ahoy! Blimey! Unfortunately, only one o' t' chutes opened so t' landin' was a bit harder than I would have liked. Ahoy! Blimey! Avast! Blimey! T' two cracks in t' fin nay only re-opened, they extended as well. Well, blow me down! Blimey! But I figured I'd fly it a second time anyway.

For t' second flight, ya bilge rat, I CHAD staged three D12-0's t' a D12-3 and two D12-5's. Ya scallywag! Avast! Blimey! I installed t' igniters and set it up on t' pad. Again t' LCO gave it a five count and pushed t' launch button. Begad! Well, me bucko, blow me down! Blimey! This flight proved t' be far more excitin' than t' first. Avast, me proud beauty! Blimey! T' rocket hadn't cleared t' rod when I heard a loud bang. T' rocket kept ascendin' but clearly, it was nay under full thrust. Ya scallywag! Blimey! It appeared t' stage but then seemed t' be under even less thrust, and it started cantin' t' one side. Begad! Fortunately, me hearties, 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, and they had obviously CATO'd. Ahoy! Blimey! One had no remnants o' t' nozzle or ejection charge cap. Begad! Blimey! 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, shiver me timbers, probably from hittin' t' blast plate on t' launch pad. Begad! Blimey! I retrieved t' rocket and inspected t' business end. Ahoy! Blimey! T' me surprise, matey, t' motor that ejected from t' back o' t' rocket be t' D12-3. Avast! Blimey! T' back end o' that motor tube was flared, probably from t' force o' a CATO. Avast, me proud beauty! Blimey! Begad! Blimey! Fortunately, ya bilge rat, enough o' t' energy from t' ejection charge did what it be supposed t' do. Ahoy! Blimey! One o' t' D12-5's had fired but t' other had not. Begad! Blimey! Curiously, me bucko, all three nose cones had ejected. Begad! Blimey! Avast, me proud beauty! Blimey! Based on observation, shiver me timbers, 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. 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, matey, I believe it be t' D12-3. Arrr! 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. Now t' rocket be flyin' on only one motor.
5. T' D12-3 fired its ejection charge, me hearties, 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. Well, blow me down! Blimey! 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. Arrr! T' bigger issue be t' lamp shade. Begad! Begad! T' hardware store has more, shiver me timbers, but t' material is too brittle for this purpose. Begad! 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! Stability was excellent. Arrr! Ahoy! T' first flight was arrow straight. Avast! Even t' ascent o' t' second flight was 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. Ya scallywag! That way, arrr, t' problem o' fittin' t' fin t' t' 3x24 airframe is simplified. Begad! Once t' cut for a single piece o' cardstock is determined, it can be duplicated for t' other two.

^*Hah!