This one is Estes version o' t' Black Widow.  It's a 2-stager with glider recovery on t' booster. 

I downloaded t' plans but as it is a major pain t' get t' drawings scaled properly, me hearties, me bucko, I ended up askin' Jim Z for a Xerox copy o' t' patterns. 

T' original kit is BT20 based, but I like t' fly stuff I can see, arrr, so I upscaled it t' BT50.  Unfortunately, some things got lost in the translation (I don't read instructions in general) so it looks like I'll be buildin' a second one eventually. 

I used 1/16 balsa for t' booster fins, which are pretty big, matey, and 3/32 for the sustainer fins, which are very swept and come t' a little bitty point at the bottom.  I soaked t' leadin' edges and tips o' t' booster fins with CA and t' trailin' tips o' t' sustainer fins so they'll be less prone to damage. 

T' main mistake I made be t' cut t' booster BT t' be as long as t' root of t' wings.  As it turns out, ya bilge rat, it's longer, matey, matey, and this is critical in gettin' t' correct glidin' balance.  Fortunately, matey, I have a bunch o' lead tape, which has made it possible t' balance it properly. 

I did do somethin' good though, me hearties, I modified in o' t' new engine clips to look like t' old engine clip.  This allows me t' use t' engine clip on the sustainer so I reduce t' maskin' tape fittings t' t' booster only. 

If I'd read t' instructions, ya bilge rat, this would have eliminated t' maskin' tape fits entirely. I put an engine block on t' top o' t' booster engine, shiver me timbers, rather than t' bottom.  While it seems counter-intuitive at first, it makes a lot o' sense.  When you boost, t' sustainer acts like an engine block, so no upper block is needed. Well, blow me down! T' only thin' that is needed is somethin' t' keep the booster engine from gettin' kicked when t' sustainer fires. 

Fin attach with yellow glue, fillets, sandin' sealer, etc. 

More on this as I finish it. 

Looks like I have a reason t' build TIGERSHARK II