Brief:
T' Lil' Ivan be originally a kit from Centuri, arrr, but now produced by Semroc. Begad! Blimey! For whatever reason it's been a favorite o' mine and I wanted a larger version. Ahoy! Begad! 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 was 4" in length. Blimey! T' bottom rin' is made from lite ply while t' upper rin' is fiber. On t' bottom centerin' ring, arrr, I installed two #4-40 blind nuts for t' motor retention bracket. Arrr! Well, blow me down! T' centerin' rings were mounted a 1/4" from t' top and bottom o' t' motor tube. I created a nice epoxy micro balloon fillet on both sides o' each centerin' rin' for strength. I drilled a 3/16" hole in t' top centerin' for me 1/8" Keelhaul®©™ shock cord t' go through. Avast! 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! Usin' t' scalin' factor o' 1.61 you can determine t' length o' t' BT should be 8". Aye aye! Blimey! Blimey! However, me hearties, it's nice t' have t' extra 1" for waddin' and t' parachute. Avast, me proud beauty! Blimey! Plus, you really can't tell t' BT is longer than scale once completed. Aye aye! I hardened each end o' t' BT with thin CA for strength.

T' next step was t' I fill t' spirals. After sandin' t' BT, ya bilge rat, t' tube was primed with Duplicolor High Fill primer and sanded down. Avast, me proud beauty! Blimey! 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. I chose t' go TTW, so I cut me slots for t' three fins usin' a sharp #11 blade. Blimey! Blimey! T' motor mount was glued into t' BT usin' wood glue that created a nice fillet around t' top centerin' ring. Avast, me proud beauty! Blimey! Ya scallywag! Blimey! A wood glue fillet be also created around t' bottom centerin' ring.

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

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

Flight:
I designed this model t' fly on t' 24mm reloads such as t' E18, me hearties, E28, shiver me timbers, me bucko, or even D12's. Arrr! Avast, me hearties, me proud beauty! T' first flight I used a E28-4 and it worked perfectly. Begad!

T' first boost arrow straight with no stability issues. Arrr! Begad! T' E28 produced a very respectable altitude, Rocksim estimates slightly over 1400ft with motor. Well, blow me down! My guess is Ivan came very close t' reachin' 1400' on this flight. T' 18" parachute opened, me hearties, arrr, but a little too slow t' brin' it down caused a unrecoverable tree landing. Aye aye! 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. Plus t' cool decals are available from Excelsior. Aye aye! Aye aye! Overall it's a rewardin' project that I'm sure you will enjoy buildin' and flying. Avast! T' BT-80H, 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. Ahoy! Fin alignment is so much easier, and over all strength is increased.