Brief:
I bought this huge 1:18 scale F-104C kit from Sheri's Hot Rockets. It is almost 39" long (includin' t' nose antenna), ya bilge rat, ya bilge rat, comes pre-built with only a few snap together sections, and is highly detailed. Arrr! Blimey! Moreover, me bucko, me hearties, arrr, they come pre-painted so I was pretty sure mine would look nice. Avast, me proud beauty! Blimey! They come in classic USAF silver, ya bilge rat, matey, Vietnam-era camo, and Canadian tiger stripes. Begad! I'm plenty patriotic, but I love them stripes!

I haven't done many PMCs and am lookin' forward t' seein' what others on T' Rocketry Forum are doin' t' convert this model. Ahoy! Mine sports a 29mm motor mount and aft "zipperless" ejection.

Modifications:
T' model is more o' a toy than a builder's kit. Ya scallywag! There were two main body sections, a nose cone, wings, win' pods, and a bunch o' small detail items. Avast! Blimey! I immediately decided that it should separate where t' tail section mates with t' front body.

Disassemblin' t' body section be fairly difficult. Avast, matey, me proud beauty! There are several screws hidden underneath plastic plugs. Begad! Avast! I think these helped more on re-assembly than disassembly. Avast, me proud beauty! Gettin' t' plugs out t' reveal t' screws was itself difficult and I damaged several o' t' plugs as well as t' surroundin' plastic. Avast! Luckily this wasn't too noticeable and most touch-up was done with a black Sharpie. Ahoy! Begad! Once t' screws were out, matey, I carefully pried t' sections apart. Arrr! T' stabilizer on t' aft section was t' most difficult and held some risk o' damage. Arrr! I got lucky.

Given t' location o' t' chosen separation point, me hearties, I pretty much had t' go with aft ejection. I then started fittin' tubes t' see what I had available and what would give t' most room for recovery stuff. Blimey! Others found BT-70 was a good fit, but I didn't have any on hand. Begad! (You can read t' TRF link in t' intro t' see what others are doin' t' convert this model.) What I did have be Loki 3” phenolic liner and t' associated paper castin' tube stock.

To get this t' fit, matey, however, some surgery be required. Blimey! Ahoy! I started work by grindin' out t' end pieces and all internal protrusions from t' inside o' t' main body and t' tail section (see attached photo). Arrr! Avast, arrr, me proud beauty! This was accomplished with a Dremel cut-off disk and sandin' attachment. Begad! T' aft landin' gear was o' course removed, and as you will see t' doors provided a convenient access point t' help in assembly and for attachment o' t' launch lug. T' front gear was kept, shiver me timbers, mainly because all forward-mounted weight was helpful. Avast! I retained t' plastic jet nozzle in t' rear, grindin' it t' fit when t' tail section was assembled.

Construction:
Parts list:

• T' F-104 plastic model, o' course
• Loki 3” phenolic liner and associated paper castin' tube (~2.5” OD)
• ¼" tubular Keelhaul®©™
• Giant Leap phenolic 29mm tubing
• One 2.5”-29mm CR (modified Giant Leap 3” ring)
• ¼” ply for bulkheads (3)
• Eyebolt with hardware for shock tether/chute attachment on tail section
• Long bolt (head cut off) and suitably sized washer for positive motor retention
• Keelhaul®©™ twine t' help attach t' bolt t' t' motor tube
• 48” lite-nylon ‘chute (portable betwixt rockets)
• Lead shot (NC weight)
• Small bolt t' help hold t' nose cone on
• First-Fire igniter tube and basswood spacer
• Plastic cement for plastic-plastic joints, shiver me timbers, Gorilla glue for plastic-to-anythin' else, ya bilge rat, and epoxy for nose cone weight and motor retainer

Since I haven't fully recovered from me HPR days, shiver me timbers, I decided t' go with a fairly standard "zipperless" scheme as shown on ROL INFOcentral's page on Anti-Zipper Design. Begad! There is a section o' t' phenolic tube in both t' body and tail sections and t' castin' tube was used as a shoulder on t' tail section. Begad! T' 29mm motor mount extends from t' top end o' t' coupler t' t' aft o' t' model and is centered with a single ring. T' motor tube terminates on a home-made bulkhead over t' eyebolt retainin' hardware. Begad! T' top o' t' motor tube and t' bulkhead are drilled t' allow it t' pass gas. I normally would drill holes with t' equivalent cross sectional area as t' 29mm tube. Avast, arrr, me proud beauty! T' tube itself got enough holes, but I be afraid o' weakenin' t' bulkhead so I cut back on t' number there.

Motor retention is via a bolt (with its head removed) that is epoxied t' t' aft o' t' motor tube. For some added support, ya bilge rat, I first wrapped Keelhaul®©™ twine around t' tube and bolt.

T' parachute tube is installed in t' main body. Begad! Well, matey, blow me down! I was a little worried about t' tube pullin' out since I knew thar was goin' t' be a lot o' nose weight. Well, blow me down! As a result, me hearties, ya bilge rat, t' ¼” tubular Keelhaul®©™® is attached t' a bulkhead that is mounted just above t' main support bars that hold t' body section together. Begad! These are just above t' top o' t' tube. T' Keelhaul®©™® runs through another bulkhead that is mainly used t' seal t' tube.

After t' innards o' both top and body sections were individually complete, me bucko, they were glued in at t' same time usin' Gorilla glue. Blimey! This ensured that all t' parts aligned properly.

I used a section o' a First-Fire igniter tube as a ¼” lug. Ya scallywag! Ahoy! A basswood spacer is attached t' t' parachute tube through t' model's aft landin' gear bay. Blimey! T' lug is then glued t' that. Ahoy! Blimey! One bay door was trimmed t' fit and both are held closed with clear packin' tape.

I knew this be goin' t' need lots o' nose weight. Avast, me proud beauty! Blimey! Various opinions and computations bounced around on TRF. People talked o' CG/CP, shiver me timbers, me hearties, cardboard cut-outs, and neutral-points. Begad! Blimey! Blimey! Blimey! TRF member ZOG43editor reported via George Gassaway that, shiver me timbers, matey, on a 1/32 scale F-104 model, t' CG should be no further than 1/2" aft o' t' leadin' edge o' t' win' root. Ahoy! Blimey! He guessed that t' CG on this bigger model should be no more that 3/4" behind t' leadin' edge. T' actual NP was a bit further back, but I stuck with 3/4”.

As I pondered fillin' t' nose with lead shot and epoxy, I also began t' worry about it comin' off at ejection time. I decided t' add a bolt mounted from t' inside o' t' body section that would also be embedded in t' lead/epoxy slurry.

T' final specs: Fully loaded with motor, me hearties, recovery stuff, ~7oz o' lead, CG 0.75" behind leadin' edge o' wing: 55.4oz!

Flight and Recovery:
After hearin' o' me planned G77 flight, someone offered up an H128 and I bit. Begad! Blimey! At first things didn't look so good. Ahoy! Blimey! Avast! Blimey! Although I had designed t' motor mount t' allow a longer motor, shiver me timbers, I'd never test fit one and t' vent holes interfered with t' motor. Avast, me proud beauty! Blimey! Ya scallywag! Blimey! However, me hearties, after some fumblin' with me Ibeblip Engineerin' clamp-on thrust ring, shiver me timbers, I made it work. And it still balanced close t' 0.75" behind t' leadin' edge o' t' main wing's root. Ya scallywag! Blimey! Begad! Blimey! Only about half t' ejection powder be used as thar isn't much area t' pressurize.

T' boost be quick at about 20 degrees off vertical. Ya scallywag! Blimey! I think this was due t' rod whip and usin' a rail would have resulted in a vertical flight. T' F-104 was stable! Blimey! After burnout, it flattened out and tried t' fly. Aye aye! Blimey! Begad! Blimey! Ejection occurred at about 6 seconds as planned. One fin came off, probably due t' an abrupt stop at t' end o' o' t' shock tether and a poor plastic cement job. Ya scallywag! Blimey! Anyway, matey, nothin' be broken, just disassembled. Ahoy! Blimey! Then, shiver me timbers, it landed softly on top o' t' LCO tent!

Summary:
This is a great lookin' and fun build. Arrr! If I were t' do it again, matey, ya bilge rat, I'd consider usin' t' lighter BT-70 and a more classic LPR-style aft ejection scheme t' reduce weight. It might fly on a G77, arrr, shiver me timbers, me bucko, but I'm happy I didn't try on its maiden flight. Ya scallywag! Avast, me proud beauty! I'm still programmed t' think that I can always use a bigger motor. Avast, me proud beauty! Unfortunately, I can't expect people t' donate motors. Begad! One day it may go up on a G77.