Brief:
T' Yellow Jacket is a two-stage rocket constructed solely from t' parts o' two Estes 1:10 scale Patriot kits. Avast! Ya scallywag! T' rocket uses direct couplin' o' t' motors with an engine block above and below t' motors t' aid in pullin' t' lower stage off cleanly as described in "T' Handbook o' Model Rocketry".

Construction:
T' two kits contain:

• 4 White (BT60) body tubes, 6-5/8" Long
• 2 Yellow (BT60) body tubes, matey, 3-¼" long (Only one needed)
• 2 Nose cones (only one used)
• 2 Blue engine mount Tubes
• 4 Red couplers, 1-½" long (Three used)
• 2 Green engine blocks
• 2 Centerin' rin' cards
• 2 Parachutes (one used)
• 2 Shock cords
• 2 Launch lugs (one used)
• 2 Sheets o' die-cut fins
• 4 Decal sheets
• 2 Mylar retainer rings (not used)
• 2 Engine hooks (not used)

Build instructions, includin' finishing:

1. Cut t' two blue motor tubes t' 2-9/16" long.
   
2. Glue t' green motor blocks flush with t' ends o' t' blue tubes. Begad!
   Mark each tube 3/8" from t' open end.
3. Glue t' solid centerin' rings 1/16" from t' blocked end o' each tube.
4. Glue t' notched rin' at t' 3/8" mark at t' other end. Aye aye!
   
5. Usin' a stick, me bucko, apply a bead o' glue 2-¾" inside one o' t' white body tubes. Avast, me proud beauty!
   
6. Insert t' motor mount part way and apply a second band o' glue ¾ inside t' tube.
   
7. Slide t' motor mount into place, makin' sure t' aft centerin' rin' is ¾" from t' aft o' t' body tube. Avast! Aye aye!
   
8. Once t' assembly is completely dry, me bucko, insert a coupler until it is flush with t' motor mount. Aye aye! Ahoy! Make sure it slides freely. Begad! Avast! Mark t' coupler.
   
9. Apply glue t' t' inside o' one o' t' yellow body tubes. Blimey!
   
10. Slide t' yellow body tube onto t' coupler, ya bilge rat, and smartly remove it. Begad! Blimey! Try nay t' let t' coupler shift. Avast! Blimey! Well, arrr, blow me down! Blimey!
    
    T' mark you made in step 8 should nay be showing. Begad! Well, blow me down!
    
11. T' coupler should have pushed up a bead o' glue inside t' yellow tube. Ya scallywag!
    
    Quickly, insert t' other motor mount's open end with t' notched centerin' rin' part way into t' body tube. Ya scallywag! Apply a bead o' glue with a stick in front o' t' lower rin'
    
    and slide t' motor mount all t' way into t' tube until it is in contact with t' coupler. Ya scallywag! Blimey! Ahoy! Blimey!
    
12. T' blocked end o' t' motor mount should be facin' t' bottom o' t' rocket, opposite t' coupler.
    
    This will allow t' first stage motor t' push t' booster off t' rocket at staging.
13. Fillet all t' motor mount centerin' rings.
14. Gather t' white body tube with t' motor mount, two red couplers and two more white tubes. Ahoy!
    
    Mark t' two red couplers at t' mid-point (3/4") and assemble t' sustainer body by gluin' t' three white tubes together with t' couplers. Begad! Blimey! T' two stage bodies will now look like photo 17.
    
15. Couple t' stages and usin' t' markin' guide from t' instruction sheet, ya bilge rat, mark t' body tubes. Begad!
    
    Extend t' fin marks across both tubes, and t' launch lug line t' entire length o' t' sustainer. Begad! Ahoy! Blimey! Make a mark 1/8" from t' stage joint on both stages. Begad! This is where you will glue t' fins, creatin' a ¼" gap betwixt fins.
16. Sand and seal t' fins from both kits.
    
    I use three coats o' wood glue thinned 50% and sand with progressively lighter sandpaper with each coat, but use whatever method you prefer. I rounded all but t' root edges, matey, but a tapered shape would certainly nay hurt.
17. Glue t' fins t' t' rocket. Blimey! Blimey!
    
    I glued both stages at t' same time in order t' get them t' line up. Begad! I also rotated t' booster t' make sure they lined up in each direction.
18. Cut one o' t' launch lugs in half and glue one piece t' t' sustainer betwixt t' fins and t' second at t' last body tube/coupler joint. Arrr! Site through t' lugs t' make sure they line up.
19. When t' fins and lugs are dry. Avast! Apply fillets t' all joints. Aye aye! I constructed a simple cardboard cradle t' hold t' rocket as I did this. Ya scallywag!
    
20. Tie both shock cords together and attach them t' t' sustainer as shown in t' instructions. Aye aye! Begad! T' nosecone and parachute also assemble t' same as t' instructions. Blimey! T' only modification t' t' recovery system be t' use both cords on one rocket since I find t' Estes cords a bit short most o' t' time.
21. For finishing, arrr, I applied two coats o' Tamiya grey primer, me bucko, matey, matey, sandin' with 400 grit betwixt coats. Aye aye!
    
    I then finished with two coats o' Tamiya Bright Yellow.
    
22. I used two o' t' kit decals t' make t' roll pattern and t' ovals betwixt t' fins. Ya scallywag! I then cut t' stripes off o' one roll pattern for t' rectangular blocks on t' booster
    
    and usin' t' scrap wood from t' fin die-cut sheet cut t' other stripes into t' angled blocks on t' sustainer.
    
23. Photo 26 shows t' completed rocket. I really like this kit and have build several incarnations o' it. Blimey! Ya scallywag! Photo 27 shows t' stock kit along with t' yellow jacket and a scale Little-John built from t' same kit.
    

Flight:
Usin' Winroc I found t' center o' pressure for t' sustainer is 18.35" from t' tip o' t' nose, matey, matey, shiver me timbers, and for both stages is 21.5". Begad! Ya scallywag! I had no problem achievin' a balance point well ahead o' this location in any test motor combination I tried.

For t' first flight I chose t' test t' sustainer with a B6-4. Ya scallywag! Avast, me proud beauty! I applied maskin' tape t' t' motor until it was a snug fit, me bucko, and as an added precaution, ya bilge rat, matey, matey, I taped it t' t' motor mount.

T' flight was perfect. Arrr! Begad! T' ejection be at apogee and be a reasonable height for a rocket o' this size.

Encouraged by that flight, I prepped for t' first two-stage flight. Begad! Aye aye! I taped an Estes C6-0 motor t' a Quest A6-4 with cellophane tape. Ahoy! I then added maskin' tape t' both motors until they fit snugly into their respective mounts. Well, blow me down! With t' A6-4 in t' sustainer, me hearties, I added a rin' o' maskin' tape around t' motor and t' motor mount. Ya scallywag! With that in place, ya bilge rat, I slipped t' booster into place until t' engine block be up against t' nozzle. I then inserted t' igniter and plug and put it on t' pad.

T' rocket lit on t' first try and climbed out with authority. Well, blow me down! Well, blow me down!

There be a slight pendulum rockin' back and forth in t' climb, with a lazy corkscrew, but it was a very windy day, so some buffetin' was nay a surprise. Arrr! Blimey! Aye aye! Blimey! Stagin' was smooth, and t' sustainer climbed out very straight. Aye aye! Blimey! T' me relief, arrr, t' booster tumbled rapidly end over end which did a good job o' slowin' its fall. Begad! Blimey! Ya scallywag! Blimey! (I had been concerned that t' reverse-fins would make it fall ballistic, matey, ya bilge rat, but it worked perfectly.) Ejection be at apogee and t' chute deployed without incident. Begad! Blimey! Overall, shiver me timbers, it was a great flight.

For t' third flight I wanted t' try t' maximum load in t' rocket. Blimey! I taped a C6-0 t' a C6-7 with cellophane tape, but could nay find me maskin' tape. Ahoy! Instead I taped t' assembly t' t' sustainer with electrical tape. Ahoy! Everythin' else went together as planned.

Takeoff was normal, and t' same pendulum rockin' was experienced in t' climb out, matey, but when stagin' occurred, all hell broke loose. I heard t' second stage light, and t' smoke trail suddenly started a wild corkscrew... Ahoy! Blimey!

T' me surprise, from t' cloud o' smoke emerged t' second stage, ya bilge rat, me hearties, matey, floatin' gently on its chute. Ahoy! Avast! T' motor continued t' fly wildly on its own, and then I heard t' "pop" o' t' ejection (So it was nay in upside-down as some have speculated).

I be able t' recover t' first and second stages, ya bilge rat, and t' me surprise t' booster's motor was intact, me hearties, shiver me timbers,

but t' sustainer's motor mount was gone leavin' only t' upper centerin' rin' attached by a flap o' paper on one side. Avast, me proud beauty!

T' second surprise be that all t' waddin' was intact

so thar had been no ejection, ya bilge rat, arrr, me hearties, or motor blow-through.

I do nay know exactly what went wrong, but I speculate that t' two motors failed t' separate completely, arrr, perhaps gettin' hung up by t' electrical tape, me hearties, and instead blew out t' side. Ya scallywag! T' pressure build up, in t' inner-stage area, forced t' lower stage off, me hearties, shiver me timbers, pullin' t' upper motor out o' t' rocket, and takin' t' motor-mount with it.

T' resultin' gyrations were enough t' dislodge t' nosecone, shiver me timbers, which pulled t' chute out when it separated, savin' t' rocket.

Summary:
T' rocket is still in good shape, and I want t' install a new motor mount in t' sustainer usin' plywood centerin' rings. Aye aye! But with that mod, it will no longer fit t' contest. Ya scallywag! I think it is still a viable design, but you might consider some way t' strengthen t' upper motor-mount if you choose t' build it.