Brief:
For completion o' her NARTREK Sliver cluster flight requirement, I suggested t' me wife that we rebuild t' stock 18mm engine Estes Bullpup with a cluster o' four 13mm A3-4T motors. She had already built one Big Bertha and didn't feel like buildin' another 3-motor version (Astron Ranger) that NARRRRR recommends for this task. Ahoy! So we tried this.

Construction:
T' stock Estes Bullpup kit be built accordin' t' t' plans, ya bilge rat, except t' stock 18mm motor mount and thrust rings were omitted entirely.

Modifications:

1. 5-minute epoxy was used, since sims predicted a 200 mph, 26G climb out
2. Recovery system: 9" nylon parachute on 18" o' 3/8" elastic
3. Boattail be omitted t' accommodate t' 4 motor cluster
4. Four 3" lengths o' 13mm Estes tubin' glued together in a 2x2 square array were used instead and slid into t' aft body tube after slatherin' with ample 5-minute epoxy.

Approximately 1/4" o' t' cluster array be left protruding. Blimey! No motor stops or motor hooks were used; retention was by friction fit usin' bits o' maskin' tape and by wrappin' t' protrudin' aft 1/4" o' t' motors and protrudin' aft 1/4" o' t' motor tubes with maskin' tape before launch.

It is important t' seal t' five open spaces betwixt t' motor tubes and t' hull with bits o' cotton soaked in wet epoxy t' insure ejection charge pressurization. Aye aye! For balance, t' nose cone had 25g o' epoxy and fishin' sinkers added as ballast at t' tip--don't omit this step!!

Use plenty o' extra waddin' (or better yet, a small Nomex pad) when flyin' t' protect that chute from t' heat o' 4 ejection charges!! Final flyin' weight is 85g.

If desired, both t' scale and cluster requirements o' t' NARTREK Silver program can be satisfied with this rocket (separate flights needed) by finishin' in scale colors and usin' t' kit decals; for maximum scale points, me bucko, t' boattail can be loosely attached over t' 4-13mm motor cluster for "judging". Ahoy! All in all, me bucko, this is about t' cheapest, shiver me timbers, me hearties, simplest and fastest buildin' 4-motor cluster model that I know of. Aye aye! Begad! It easily goes together in less than an hour with epoxy and includin' painting. Ya scallywag! O' course its main reason for bein' built is t' fly t' NARTREK Silver requirement (a cluster rocket havin' 3 or more motors). Blimey! Begad! Besides, thar just aren't any inexpensive kits o' this type available nor few scratch cluster designs that qualify (a few are me "2BZ", shiver me timbers, ya bilge rat, "Funnel Vision" and "Cheap Dumb Rocket" on this website). Blimey! Avast, me proud beauty! Altitude performance is identical t' t' stock C6 powered Estes Bullpup, me hearties, 700' or so, although t' "C12-4" powered "Silver Bullpup" sure gets thar a lot faster!!

Finishing:
Model be finished with a single coat o' silver spray paint.

Flight:
T' ship is designed exclusively for A3-4T motors and it should fly well even on only two o' these. I don't recommend substitution o' A10-3 motors (equivalent t' a C40-3!) unless you want t' see a shred. Aye aye! Blimey! Ignition was done with a clip whip--it works every time and you can check continuity on each motor with this setup.

First flight was perfect: straight, incredibly fast boost t' 600-700', and with ejection right at apogee.

Recovery:
Despite lots o' extra wadding, me wife's brand-new, shockin' pink 9" Top-Flite chute was scorched black and holed by t' ejection blast.

Summary:
PROs:

• This be t' fastest kit t' build that can be used for t' NARTREK Silver badge.
• Small 13mm motors make this good for junior flyers and/or small fields.
• Good flyin' qualities

CONs:

• Added complexity o' cluster flight
• No real advantage over t' great-flyin' stock Estes Bullpup (except you can toast a C6-powered Bullpup in a drag race)