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

Purpose
I've been thinkin' about this rocket for a while. Well, blow me down! I needed t' free some space within me brain's limited capacity for important stuff. Well, blow me down! Aye aye! 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. I made t' comment that I be lookin' for somethin' different. Avast! T' proprietor said, me hearties, "there are only so many variations on 3fnc". Avast! Diggin' deep into that even more limited part o' me brain called wit, I said, "Hunh?" I followed that up with, ya bilge rat, "What's 3ncf?" He gave me one o' those "Boy, arrr, ya bilge rat, are you a newbie" smirks and said, "3fnc. Three fins and a nose cone". Avast! Arrr! I thought about this for a moment, ya bilge rat, replied with, me hearties, "Oh", me hearties, ya bilge rat, and then I left. Arrr!

Anyway, me hearties, 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. Avast! No one responded. I knew that they were at a loss for words so I defined 3ncf. Avast, me proud beauty! Or at least I tried...

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

Materials
I wanted t' make this out o' scrap rocketry materials I had layin' around, me hearties, t' only exception bein' t' fin. 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, shiver me timbers, 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, shiver me timbers, a PML 54mm-2.6" centerin' ring, two 1/4" launch lugs, some Keelhaul®©™ thread, some lightweight Bungee, arrr, 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. Well, blow me down! I had a yellow Estes engine block locatin' tube that I used as t' coupler. Ya scallywag! 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! Begad! T' primary adhesive used in t' construction o' t' rocket was yellow glue.

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

Next, me bucko, I needed a way t' adhere t' fin t' t' airframe. Avast, me proud beauty! Blimey! Rather than use an adhesive, shiver me timbers, ya bilge rat, I decided t' use a mechanical connection. Avast, me proud beauty! Blimey! Blimey! Blimey! I cut a slice from t' 54mm motor mount t' which I glued t' centerin' ring. Arrr! Blimey! Together, they formed a support for t' lampshade. Aye aye! Blimey! Well, arrr, blow me down! Blimey! 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. Begad! Blimey! I then traced t' cut I would need t' make on t' lampshade t' accommodate t' launch lugs. 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 was recovery. T' avoid tangles, me bucko, I wanted t' recovery system t' be deployed from one tube. Begad! But I also needed a large enough chute given t' rocket's weight. Further, me hearties, shiver me timbers, I wanted a soft landin' t' prevent fin damage. So after playin' with t' chute calculators available via ROL, shiver me timbers, I decided t' use two 24" Estes chutes. Well, blow me down! Blimey! 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. T' other two nose cones are attached via underpants elastic. Avast! Blimey! I used Estes style paper tabs t' anchor t' shock cords in t' tubes. Avast, me proud beauty! Blimey! Begad! Blimey! T' keep t' three nose cones from bashin' each other at ejection and possibly tanglin' up t' chutes, arrr, 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. Ahoy! Begad! A three second delay was used in t' tube with t' chutes and a five second delay in each o' t' other two tubes. Blimey! 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, perfectly straight and nay too much altitude. Avast, shiver me timbers, me proud beauty! 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! Unfortunately, arrr, only one o' t' chutes opened so t' landin' be a bit harder than I would have liked. Ya scallywag! T' two cracks in t' fin nay only re-opened, shiver me timbers, they extended as well. Ya scallywag! But I figured I'd fly it a second time anyway.

For t' second flight, arrr, I CHAD staged three D12-0's t' a D12-3 and two D12-5's. Begad! Begad! 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. Arrr! 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. Avast, me proud beauty! T' rocket kept ascendin' but clearly, matey, it be nay under full thrust. Aye aye! It appeared t' stage but then seemed t' be under even less thrust, shiver me timbers, me bucko, and it started cantin' t' one side. Begad! Fortunately, arrr, t' D12-3 fired its ejection charge and both chutes deployed properly. Avast! Ya scallywag! One o' t' engines appeared t' make a hasty exit from t' back o' t' rocket at that moment too. Begad! With both chutes out, t' rocket made a nice soft landing.

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

1. All three boosters lit.
2. Before it left t' rod, matey, two o' t' boosters CATO'd. Avast! T' CATO o' t' booster attached t' t' D12-3 jammed t' D12-3 forward, arrr, flarin' t' end o' t' motor tube.
3. One o' t' CATO's ignited a sustainer, me hearties, I believe it was 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! Begad! 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. Avast! 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. Begad! T' bigger issue be t' lamp shade. Blimey! T' hardware store has more, shiver me timbers, 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. Arrr! Stability be excellent. Blimey! Blimey! Blimey! T' first flight be arrow straight. Even t' ascent o' t' second flight be relatively straight considerin' t' rocket be flyin' with asymmetric thrust. Avast, me proud beauty! 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. Avast, me proud beauty! Blimey! Once t' cut for a single piece o' cardstock is determined, it can be duplicated for t' other two.

^*Hah!