Brief:
Scale modelin' o' t' TOW antitank missile is a challengin' rocketry project; I don't see that it has been attempted before. Arrr! It is an "8FNNC" configuration, 8 Fins No Nose Cone, with a blunt end that can't be good for aerodynamics and that has t' be custom crafted. Avast! Ya scallywag! Add t' this a very far forward CP requirin' lots o' nose weight that would be expected t' further degrade the flyin' qualities o' an already draggy rocket. Begad! Nay much fun t' fly something like this usually. Avast, me proud beauty! Avast, me proud beauty! I built this 1/3-scale model only t' verify CP and CG for a full-scale K445-powered TOW 2A project I am starting. I needed t' know just how much nose ballast t' model would require and if it would even be practical to try t' model. Blimey! T' "real" TOW 2A solves this balance problem easily with its 35lb shaped-charge warhead.

Construction:
I'm nay usually into scale modeling, matey, shiver me timbers, but t' TOW-2A antitank missile with its long nose-probe fuse caught me eye as somethin' interestin' t' do with the nose-mounted parachute mortars I had been experimentin' with (see "Aquafina" and "Bad Dad" examples on this website). Ya scallywag! The 1/3-scale balance-test model was built for D12 and E30 24mm power usin' a 2" postal mailin' tube as t' hull. Well, blow me down! Ahoy! Sort o' novel be t' use o' the plastic end caps o' t' tube as ready-built centerin' rings for t' 24mm motor tube that runs t' full length o' t' rocket with t' "nose-fuse" formin' t' parachute mortar. Begad! Well, blow me down! T' forward centerin' rin' also forms t' blunt nose o' t' missile. Ya scallywag! Arrr! T' model is thus a "rocket-in-rocket" design. T' full-scale model will utilize 6" tubin' and a 54mm motor tube/parachute mortar. Aye aye! Ahoy!

T' construction is straight-forward. Begad! Blimey! Five-minute epoxy was used throughout. 8 fins cut from 1/16" basswood and laminated on one side with 1/64" plywood, one 14.25" x 2" section o' mailin' tube, shiver me timbers, t' two plastic end caps from t' mailin' tube with t' 1" diameter reinforcing "dimples" cut out from their centers with an X-Acto knife, arrr, one 18" section o' 24mm motor tubin' (I originally used Estes BT50 tubing, which was a big mistake), me hearties, shiver me timbers, an Estes motor hook, ya bilge rat, and an 18" Top Flite nylon chute. Begad! Avast! Assembly sequence:

1. Fin sets glued onto t' body tube flush with t' base (tail vanes) or 6 1/8" from t' base (wings), and 45 degrees apart. Vanes are each 2" x 7/8", wings are each 2 3/4" x 1 1/8" (diagonal tip is inset 1/4" from leading/trailin' edges). Ya scallywag! T' fin base attachment points were reinforced with 3/4" bits o' popcicle stick scrap.
2. T' 18" long motor tube is fitted with an Estes motor hook on t' aft end in t' usual fashion. Avast, me proud beauty! Motor tube is pierced 6" from t' front end and 30" o' parachute cord is passed through and knotted/epoxied in place; this becomes t' recovery system shock cord.
3. Aft plastic mailin' tube cap is epoxied in place after roughin' with sandpaper and notchin' t' openin' in this "centerin' ring" to accommodate t' motor hook.
4. T' motor tube with epoxy applied t' t' aft end is now inserted from t' front end, ya bilge rat, me hearties, matey, passed through t' aft end cap, followed by t' forward plastic mailin' tube cap is passed BACKWARDS over t' protrudin' front end of the motor tube and epoxied in one operation t' t' motor tube and t' t' end of the mailin' tube, shiver me timbers, me hearties, me bucko, providin' a short, shiver me timbers, flat, fixed "nose cone". Aye aye! This all has t' be done at once because t' front and end caps are t' only points of attachment and centerin' for t' central motor/parachute tube.
5. A 3" long 1/4" launch lug is epoxied in place along side one of the wings, matey, with t' forward end extendin' exactly 1.5" past t' wing leadin' edge; t' forward end o' t' launch lug gives 1-calibre stability, and is t' balance point for t' model loaded with a 45g Aerotech E30 motor. Arrr! This is achieved by addin' 60g o' lead fishin' sinker ballast t' t' 120g rocket airframe (epoxied and duct-taped in un-scale fashion t' t' sides o' the "nose fuse"! There is probably a more elegant and less ugly way to add t' nose ballast, but for now you'll just have t' eat t' scale points.
6. T' 1/3 scale prototype be painted after t' 2nd test flight in Testors flat olive drab for a military (although non-scale) appearance. Begad! Begad! The actual TOW missile is finished in an uncool and quirky patchwork o' bright metals and protective blue, lime, me bucko, and gray primer coatings (since it lives its life in a sealed transporter launch tube and nobody sees what it looks like).

Flight:
Simulation based on a guesstimated Cd o' 1.25 gave a 10G boost o' 340' at 135 mph on a D12-5--about t' same performance expected for an Estes Big Daddy on this motor. Begad! Amazingly, me hearties, me bucko, t' first flight with this motor gave a flight that was visibly much higher and faster than any Big Daddy--not t' draggy pig I had expected at all. Begad! Boost was straight up and perfectly stable. Ahoy! Chute popped out right at apogee and descent was brisk but soft enough that I didn't break off a fin as I thought eventually might happen.

I made an additional flight on t' D12, perfect again, matey, and decided that the balance point was good enough t' apply t' t' full scale version. Ahoy! On t' third test flight with a D12-5, me hearties, matey, matey, t' ejection charge blew t' motor tube apart, sendin' t' forward section with t' chute out t' front and t' aft section with t' spent D12 out t' back, t' twin plastic end caps slowly spiraling down like miniature Frisbees. Avast, me proud beauty! T' empty body tube floated gently down and landed with no damage or fin breakage. Ya scallywag! Cause was a parachute packed too tight and failure o' t' thin-walled BT-50 tubin' at its unsupported midpoint. Begad! I replaced t' BT-50 tubin' with thicker-walled 24mm motor tubing, me hearties, which I should have used in t' first place, and epoxied everythin' back together. Well, arrr, blow me down! T' problem has nay recurred. Well, blow me down! I never did fly it on an E30...it just flies too darn well on the D12-5 t' need one. I am now usin' an estimated Cd o' 0.85 t' plan flights and that seems about right.

Summary:
All things considered, ya bilge rat, arrr, t' 1/3-scale TOW-2A is an easily built and great flying scale missile. Arrr! It would be a good candidate for a club contest or t' NARTREK Silver requirement, me bucko, since thar's lots o' scale documentation on t' Web. Except for t' parachute, it takes a couple o' hours and about $5 t' scratch build -- how many 1/3-scale rockets can claim this, and fly well on a D12?

PROs: I have been just amazed at how well t' TOW 2A performs, matey, despite the blunt nose, t' weight and all those fins. In retrospect, me hearties, maybe this isn't so surprising, arrr, matey, since it was designed by "real" rocket scientists t' do just that. I am usin' t' dimensions and balance points t' design the full-scale high-power model. Arrr! It is fun t' fly, sturdy, and gets a lot of "Whatsat? Wherdjagethat?" comments at t' field. Ya scallywag! Avast! It goes together quickly and is dirt-cheap t' scratch build. Avast, arrr, me proud beauty! T' open-ended parachute mortar works great. Avast! Begad! It should really cook on an E30-7 or F24-7 (Sims say 1000' at 275 mph).

CONS: As a scale model, me bucko, ya bilge rat, it still has a way t' go--the huge fishin' sinker weights need a better home (I'm workin' on it), and t' aft fins should probably be attached through-the-wall t' t' motor tube because I finally did break a couple off. Avast! Blimey! T' biggest scale limitation will be tough t' fix--the twin motor exhausts on t' actual TOW missile exit amidships, just aft o' t' wings. This would be really tough t' do in a model, me bucko, so t' TOW will remain a difficult scale rocketry project if it's scale points you're after. Avast, me proud beauty! Blimey! Arrr! Blimey!