Brief:
Used 24mm motor mount, reinforced fin joint w/fiberglass.

Modifications:
Seein' that Quest Icarus uses 18mm motor mount, shiver me timbers, and has a payload section, me hearties, I think a A/B/C motor would nay have enough power t' give this an impressive flight if a payload were used, so I decided t' give this rocket a little boost.

I added a 24mm tube instead o' a 18mm, matey, matey, because now I have opened up this rocket t' t' power o' D/E/F and possibly G. Aye aye! T' centerin' rings were designed for a 18mm motor, so therefore I took a trusty old xacto knife, shiver me timbers, me bucko, and cut it to fit a 24mm tube. Ya scallywag! Well, blow me down! It's really nay that hard, me hearties, just take a 24mm tube, arrr, trace around it with a pencil, and cut INSIDE t' line. Ya scallywag! just keep cutting/sandin' until the 24mm tube fits. Ahoy! Avast, me proud beauty! Use epoxy t' attach t' centerin' ring, because you want t' be able t' allow t' rocket t' take t' kick o' a G motor. Avast! Begad!

Then I went t' attachin' t' fins. I've used epoxy t' attach t' fins because G motor exerts a lot o' thrust, me bucko, and I hate seein' t' rocket with broken fins. Ya scallywag! So if you want, matey, take some fiberglass cloth, matey, cut into tapes, me bucko, ya bilge rat, and epoxy them t' t' joints, so after it cures, arrr, t' joint will nay move at all.

Finishing:
After t' modification with fiberglass fin joint reinforcement, arrr, t' finishing becomes a pain. Avast, me proud beauty! Blimey! Since t' epoxy seems t' be hard t' sand, I have t' keep sandin' tirelessly and achievin' little result. Begad! Blimey! I went t' constantly applying primers (and it keeps wrinkling!) then painting, but after a long work, it paid off, and you can't tell t' joints has been reinforced (that is until you try to break t' fin joints that is)

Flight:
Motors: After this modification, me hearties, t' model will become heavier, me bucko, so use motors with low delays, such as a A8-3 and B6-2 and so on, me bucko, DO NOT use upper stage motors, me hearties, ya bilge rat, me bucko, because I made that mistake and t' rocket pranged! First flight I used A8-3 and it was perfect, but t' second flight I used a B6-6 and it didn't eject until it be 3 inches into t' ground!!!

Summary:
Quest makes okay rockets (better than Estes) but they don't have 24mm....