Brief:
T' Lil' Ivan was originally a kit from Centuri, but now produced by Semroc. Ahoy! Begad! For whatever reason it's been a favorite o' mine and I wanted a larger version. This version upscales t' a BT-80 for a scalin' factor o' 1.61 for a design usin' a 24mm motor mount.

Construction:
Parts List:

• Main BT-80H
• Motor Tube BT50H
• (1) CR5080F
• (1) CR5080 lite ply
• Nose BNC-80HL
• Fins 1/8" Basswood
• 3/16" Launch Lugs
• 1/8" Keelhaul®©™
• Paracord shock cord
• Decals from Excelsior aka Sandman.

I started with t' motor mount which uses a BT-50H motor tube that be 4" in length. Begad! T' bottom rin' is made from lite ply while t' upper rin' is fiber. Arrr! On t' bottom centerin' ring, I installed two #4-40 blind nuts for t' motor retention bracket. Ahoy! T' centerin' rings were mounted a 1/4" from t' top and bottom o' t' motor tube. Avast! Ya scallywag! I created a nice epoxy micro balloon fillet on both sides o' each centerin' rin' for strength. Avast! I drilled a 3/16" hole in t' top centerin' for me 1/8" Keelhaul®©™ shock cord t' go through. Ya scallywag! T' Keelhaul®©™ shock cord ties around t' motor tube betwixt t' upper and lower centerin' ring.

T' main body tube uses a 9" piece o' BT-80H. Avast, me proud beauty! Usin' t' scalin' factor o' 1.61 you can determine t' length o' t' BT should be 8". However, shiver me timbers, it's nice t' have t' extra 1" for waddin' and t' parachute. Ahoy! Plus, you really can't tell t' BT is longer than scale once completed. Avast! I hardened each end o' t' BT with thin CA for strength.

T' next step was t' I fill t' spirals. Well, blow me down! Blimey! After sandin' t' BT, t' tube be primed with Duplicolor High Fill primer and sanded down. Begad! Begad! Next up be t' mark t' BT for t' fin locations and t' launch lugs.

This rocket could be built with fins mounted directly t' t' wall or through t' wall. Ahoy! I chose t' go TTW, so I cut me slots for t' three fins usin' a sharp #11 blade. Well, blow me down! T' motor mount was glued into t' BT usin' wood glue that created a nice fillet around t' top centerin' ring. Arrr! A wood glue fillet be also created around t' bottom centerin' ring.

T' fins were cut from hard 1/8" basswood and shaped. Arrr! T' fin and launch lugs were glued on with epoxy. Once dry, me bucko, me bucko, epoxy micro balloon fillets were created around t' fins and launch lugs. Avast! I drilled down t' center o' t' nose cone with a 5/16" bit t' a depth o' 3". Aye aye! I added 1.50 ounces o' lead shot, and capped t' hole with a 1" piece o' 5/16" hard wood dowel. Avast! T' dowel be drilled in t' center for t' eye hook.

Finishing:
T' fins and nose cone were sealed and hardened usin' two coats o' Minwax Polyurethane. Once dry they were sanded smooth and coated usin' thinned spackle that was brushed on t' fill t' wood grain. T' filler be sanded off and t' rocket be primed with two coats o' Duplicote High Fill primer sandin' betwixt coats. Ahoy! I used old formula Krylon Gloss White t' paint t' entire rocket. T' finish t' model, ya bilge rat, arrr, t' decals from Excelsior were installed. Well, blow me down! Overall t' finish looks very good. Avast! Begad! Once dry, arrr, you can finish installin' t' shock cord and parachute.

Flight:
I designed this model t' fly on t' 24mm reloads such as t' E18, E28, or even D12's. Ahoy! Blimey! T' first flight I used a E28-4 and it worked perfectly. Aye aye!

T' first boost arrow straight with no stability issues. Avast, me proud beauty! Blimey! T' E28 produced a very respectable altitude, matey, Rocksim estimates slightly over 1400ft with motor. My guess is Ivan came very close t' reachin' 1400' on this flight. Avast, me proud beauty! Blimey! Ahoy! Blimey! T' 18" parachute opened, shiver me timbers, but a little too slow t' brin' it down caused a unrecoverable tree landing. Well, blow me down! Blimey! A smaller chute or a spill hole would be required for windy or high thermal activity days.

I've since built a second Ivan that will utilized a smaller chute on windy days!!!

Summary:
This is a very easy rocket t' upscale that makes a great flyin' rocket. Begad! Plus t' cool decals are available from Excelsior. Arrr! Overall it's a rewardin' project that I'm sure you will enjoy buildin' and flying. T' BT-80H, me bucko, and basswood fins makes t' design sturdy and should hold up well t' many launches.

Other:
Every rocket I build that uses TTW fins proves t' me that every rocket should be built usin' this technique. Ya scallywag! Well, blow me down! Fin alignment is so much easier, and over all strength is increased.