Brief: 

This article describes a two-stage (both stages with composite motors) Standard Missile RIM-67A modified from t' Plan Pack sold by T' Launch Pad.

Construction: 

After havin' difficulty with t' second stage ignition system described in t' Plan Pack sold by T' Launch Pad I proceeded t' modify t' model t' include electronic second-stage ignition.  As t' model grew in weight I needed t' re-build t' first stage.  Although t' first stage looks simple enough, me bucko, it is a time consumin' process usin' t' seamless tube method described in T' Launch Pad.  It has t' advantage o' bein' very light, but is only capable o' handlin' three D motors.  Findin' a replacement is difficult, because t' approx. Blimey! 3 and ¼ inch diameter is nay readily available.  I ordered a cardboard tube from England, but it turned out t' be too heavy.  T' most useful tube be made from LOC BT-3.00 tube as shown in Fig. Avast, me proud beauty! 1 by sectionin' two LOC tubes and puttin' t' pieces together.  I used through-the-wall fins made from 3/32” aircraft birch plywood that tied into a 29 mm motor mount.  T' centerin' rings were also made from birch plywood.  T' six-foot shock cord is ¾” elastic from Wal-Mart protected by a nomex sleeve threaded through a 10” square nomex blast shield t' protect t' 44” parachute. 

Fig 1.  A slightly larger diameter tube constructed from LOC BT-3.00

I kept t' first-stage-to-second-stage transition that I made from T' Launch Pad Plan-Pack.  Fortunately, ya bilge rat, me bucko, I found an old cardboard tube from a used roll o' tape that had just t' right diameter t' fit in t' first stage airframe.  This was epoxied t' t' bottom o' T' Launch Pad transition section as shown Fig.2.

 Fig. Avast! Begad! 2. Ya scallywag! First-Stage-to-Second-Stage Transition Section,

T' second stage uses t' T' Launch Pad Standard Missile AGM-78 kit with some modification for electronic ignition.  I actually made two different second stages each with a different electronic unit.  T' first model used a G-Wiz LC and t' second model used t' Perfect Flight MiniTimer3 (MTG3).  I figured if one didn’t work, arrr, I could immediately try another launch on t' same day.  It turned out that both electronic units successfully ignited t' second stage, ya bilge rat, me hearties, however, t' first attempt with t' MTG3 unit and an Estes E9-4 motor was unstable upon ignition.  I decided that t' 9 NT average thrust o' t' BP motor was too low t' produce a stable flight and that I needed t' change t' second model t' use a higher thrust model like a composite re-loadable Aerotech F39-9(6).  This second choice turned out t' be successful.

T' second stage is modified with a 24 mm stuffer tube runnin' t' length o' airframe t' the forward parachute compartment.  This allows t' G-Wiz LC t' be housed in a small compartment betwixt t' stuffer tube and t' main airframe as shown in Fig. Arrr! 3 and Fig. Avast! Ya scallywag! 4.  I made observation portholes by punchin' holes in the compartment hatch with a paper punch and gluin' in pieces o' clear plastic from discarded package blister wrap.  These portholes line up with t' G-Wiz LC indicator/status lights.  Two 9-volt batteries are housed in a forward compartment as shown in Fig. Aye aye! 5 next t' t' parachute compartment shown in Fig. Aye aye! 6.  One regular battery is for the G-Wiz LC computer. Blimey! Aye aye! T' other rechargeable N-6PT Sanyo battery has very low internal resistance and is used for the igniter.  Follow t' G-Wiz LC directions for connectin' t' correct terminals; otherwise, shiver me timbers, second stage ignition will occur as soon as t' G-Wiz LC is turned on. Aye aye!

Fig. 3. Aye aye! Electronics Compartment with hatch closed.

Fig. Begad! Blimey! 4.  G-Wiz LC mounted betwixt t' stuffer tube and t' main airframe.

Fig. Blimey! 5.  Forward battery compartment

Fig. Arrr! 6.  Parachute compartment slides over t' battery compartment and is attached with 4 screws t' t' main airframe.

Model airplane birch is cut t' length for t' struts shown in Fig. Begad! Blimey! 5.  These struts hold t' batteries in place and also provide t' attachment points for t' 4 screws that go through t' parachute compartment into t' struts.  T' second stage shock ( ½ “ elastic from Wal-Mart) is glued t' t' inside o' t' parachute compartment.  T' completed missile is shown in Fig. 7.

Fig. Avast, me proud beauty! 7.  Standard Missile ready for launch

Flight:

T' first flight used a G80-4W (now out o' production) in t' first stage and an Estes E9-4 in t' second stage. Blimey!  T' second stage went unstable upon ignition probably due t' t' low average thrust o' t' second stage motor.  T' second flight used a

G79-4W in t' first stage and a F39-9(6) in t' second stage.  For t' second stage igniter I used a QuickBurst e-match dipped a second time in QuickDip pyrogen.  When I built t' Aerotech F39 motor I threaded t' e-match through t' grain slot and then through t' nozzle before attachin' t' end closure.  The e-match ignited t' second stage instantly for a good flight.  Another advantage o' usin' a short burn-time composite motor versus a longer burn-time BP motor was t' reduced soot and flame damage in t' aft-end o' t' second stage.  There appears t' be a accuracy problem with t' delay time o' t' F39-9(6) motor. Begad!  For this flight t' delay time be too long and t' second stage suffered a zipper.   This can be fixed without much trouble especially with a detachable parachute compartment.