Brief:
AT Cheetah stretched by 34" includin' 9" payload section. Begad! Ya scallywag! Motor tube extended t' handle 11" motors and screw-on positive motor retention.

Modifications:
This is a fairly straight forward extension o' t' AT Cheetah, with extra care taken t' strengthen t' motor section t' handle single use motors up t' 11" long, me hearties, particularly me favorite: t' Ellis Mountain H50. Begad! Aye aye! I used JB Weld epoxy for any components exposed t' motor heat, and Devcon 5 minute epoxy everywhere else.

A 34" length o' 1.88" tube (BMS # T-188-34) be cut off at 9" t' provide body extension and payload section. Avast, me proud beauty! Both 1.88" couplers are marked around their midpoint. Begad! One is glued t' t' mark into t' provided Cheetah body tube, arrr, arrr, matey, and t' 25" extension glued onto that. Begad! Aye aye! Fold t' AT elastic shock cord double into a loop and tie a knot in t' ends. Well, blow me down! Run one end o' t' loop through t' payload section screw eye, and run t' other end o' t' long loop through t' part stuck through t' eye and pull it tight. Well, blow me down! Ya scallywag! T' screw eye is fitted through t' bulkhead and glued t' t' other 1.88" coupler (eye/shock cord t' t' inside o' coupler). Blimey! This coupler is then glued bulkhead first into t' 9" tube up t' t' mark.

Slide onto AT provided 12" motor tube (in order) one centerin' ring, both Fin-Lock assemblies, arrr, second centerin' ring. Well, blow me down! T' AT motor hook is nay used. Well, blow me down! Place "C" clip into PVC bushin' cap and screw onto threaded fitting. Blimey! Begad! Place this onto end o' AT motor tube, shiver me timbers, arrr, pushed up until t' clip stops at t' motor tube, me bucko, and mark t' tube at t' cut end o' t' fitting. Avast, me proud beauty! Avast! Remove t' PVC parts, spread glue on t' marked end o' t' tube up t' t' mark, and push t' fittin' back on over t' glue until it stops. Begad! Well, blow me down! If t' fittin' is loose on t' tube, shiver me timbers, place strips o' tape on t' tube t' make t' fit tighter but do nay entirely cover t' end o' t' tube--there must be bare motor tube exposed t' bond t' t' epoxy. Aye aye! Do nay place glue on t' inside o' t' PVC fitting. It will get pushed into t' cap and glue t' retainer together. Begad! Well, arrr, blow me down! Take care no glue gets on t' removable parts or t' threads. Avast, me proud beauty! Push t' aft centerin' rin' down against t' PVC fitting, usin' t' glue pushed out by fittin' on t' threaded section t' form a fillet. Arrr! Set aside t' dry.

Construct t' upper motor tube section usin' t' 8" piece o' 29mm motor tube, me hearties, t' AT baffle and coolin' mesh, accordin' t' t' kit instructions. Attach t' recovery section screw eye t' t' baffle and tie t' tubular nylon t' it.

Test fit t' 2" long 29mm coupler into t' lower motor section. Begad! Blimey! Place it so that thar be 11" t' 11 1/8" o' space betwixt t' coupler and t' retainer "C" clip. Well, blow me down! Blimey! Mark t' coupler and remove it. Avast! Blimey! Well, ya bilge rat, blow me down! Blimey! Cover t' aft half o' t' coupler up t' t' mark with epoxy and slide it into t' lower motor tube only up t' t' mark. Ya scallywag! Blimey! Smooth t' glue that got pushed up by t' tube onto t' upper half o' t' coupler. Begad! Blimey! Slide t' upper motor tube down onto t' coupler until t' two motor sections meet. Make sure you do nay push t' coupler down into t' lower motor section. This can be done by holdin' t' lower section tightly with a pair o' pliers on t' top 1" (over t' coupler) while twistin' t' upper section onto t' coupler. Cut t' BT-55 coupler down t' side. Spread t' excess glue from joinin' t' tubes down 1" onto t' aft motor section and up several inches onto t' forward motor section. Well, blow me down! Blimey! Add more glue if necessary. Arrr! Blimey! Ahoy! Blimey! Pry open t' BT-55 coupler and place it over t' motor tube, arrr, ya bilge rat, 1" onto t' aft motor section and t' remainder on t' upper section. Begad! Blimey! This will strengthen t' motor section joint as well as t' upper part o' t' tube which will be subjected t' hot ejection gasses. Begad! Blimey! Hold t' coupler tight over t' motor tube with tape or rubber bands while it dries. Avast! Blimey! You can remove t' bushin' cap and "C" clip t' make sure no glue seeps into it.

Once t' motor tube assembly is dry, test fit it into t' aft end o' t' body. Arrr! Blimey! Begad! Blimey! Adjust t' Fin-Locks t' their proper placement inline with each other and directly under t' ends o' t' fin slots. Ya scallywag! Blimey! Once in place, ya bilge rat, me hearties, me hearties, remove t' motor section and test fit t' fins into t' Fin-Locks. Once you're sure they fit, matey, matey, replace t' motor tube into t' body and test fit t' fins through t' slots.

Once you're certain all t' placement is right, remove t' fins carefully and extract t' motor tube. Place a drop o' CyA at t' Fin-Lock ring/motor tube joint so they don't shift. Avast! Place a generous fillet o' epoxy on both side o' both Fin-Lock rings and t' motor tube. Ahoy! Do NOT get this in t' Fin-Lock channels. Wipe some o' t' epoxy up over t' rings t' form "bridges" o' epoxy from t' motor tube, over t' rings betwixt t' fin channels, arrr, matey, down t' t' tube on t' other side o' t' ring. Blimey! Slide t' upper centerin' rin' down t' t' forward Fin-Lock and add a fillet t' t' forward side o' t' forward centerin' ring.

When t' motor section is completely dry, arrr, place epoxy inside t' body tube where t' forward centerin' rin' will sit, takin' care t' keep t' tubular nylon from gettin' epoxy on it. Push t' motor section into t' body all but 1". Begad! Avast, me proud beauty! Wipe epoxy on t' forward side o' t' aft centerin' ring, ya bilge rat, sufficient t' drip off once placed inside and bond t' t' body. Begad! Slide t' motor section t' rest o' t' way into t' body, alignin' t' Fin-Locks directly under t' slots. Blimey! Ya scallywag! Wipe epoxy t' entire length o' t' bottom edge o' t' fin tab. Ya scallywag! Ya scallywag! This will bond into t' Fin-Lock channels, t' t' motor tube, and will squeeze out a little while insertin' which can be smoothed over t' fin/body joint as a fillet. Ya scallywag! Ya scallywag! Fit t' fins and set aside t' dry.

Tie a small loop in t' upper end o' t' tubular nylon. Blimey! Stick a few inches o' t' elastic loop through t' nylon loop. Blimey! Push t' payload section through t' protrudin' elastic loop and pull tight until t' elastic tightens a double loop on t' nylon. Ya scallywag! Fit t' nose cone on t' payload section and t' payload section onto t' body, me hearties, shiver me timbers, usin' maskin' tape as necessary for a good fit. Well, blow me down! If removed, replace t' cap on t' motor retainer. Avast, me proud beauty! Add t' lugs, shiver me timbers, or use buttons if you prefer. Blimey! You are now ready for finishing.

Construction:
You need t' followin' items:

• 1 AT Cheetah kit
• 1 34" length 1.88" diameter body tube
• 2 1.88" tube couplers
• 1 1.88" bulkhead
• 8" o' 29mm motor tube
• 1 BT-55 coupler
• 2" 29mm coupler stock
• 1/8" wood screw thread screw eye
• 8' o' 9/16" tubular nylon shock cord
• 1/2" t' 3/4" o' male threaded PVC cut from 1 1/4" pipe fittin' such as pipe nipple
• 1 1.25" PVC bushin' cap
• 1 1" C-clip

AeroTech recommends only CA glue and that works for most o' t' build. Aye aye! Fittin' t' motor section into t' body requires a bit more flexibility and epoxy gives that. Blimey! Aye aye! Also, repeated exposure o' both CyA and regular epoxy t' motor heat can weaken it. Ya scallywag! Thus, I recommend JB Weld for any application where heat will affect t' part.

Finishing:

Finishin' is up t' t' individual but I favor appliance epoxy paint. It's an incredibly tough, thick, shiver me timbers, gives a smooth finish, and requires (in fact suggests) no primer t' be used. Arrr! Blimey! It takes a color coat well, me hearties, arrr, however, anythin' added t' an appliance epoxy paint (includin' a second coat o' t' same paint) must be added within 30 minutes or else t' surface will wrinkle. Begad! Blimey! As shown in t' picture, matey, I had a bit o' fun with t' included "Cheetah" decal.

Flight:
T' motor retainer is simple t' use: unscrew it, me bucko, place t' motor into t' tube, me bucko, and screw it on. Avast, me proud beauty! Blimey! I tend t' lose t' "C" clips, matey, so I buy extras regularly, matey, me bucko, and I tack them t' t' inside o' t' bushin' cap with a drop o' CyA.

This motor section will fit any 29mm motor up t' 11" length. Aye aye! For anythin' shorter you'll need a spacer. I bought a full length piece o' 29mm coupler stock and cut pieces off t' t' proper lengths for t' common motors sizes. Well, blow me down! Ya scallywag! I keep t' rest around t' cut as necessary for other motors. Aye aye! Avast, me hearties, me proud beauty! 29mm coupler stock will also serve as an adequate 29/24mm adapter. Avast, me proud beauty! I cut two 11" sections and glued thrust rings/engine blocks inside them at 3.75" (F21) and 4.8" (F32/F72) lengths. Begad! It requires several wraps o' tape t' get a good gas tight seal, ya bilge rat, but tabs on t' "C" clip are large enough t' retain a 24mm motor with a diameter-only adapter.

Maiden flight be on an Aerotech G110-10. Perfectly straight boost, me bucko, with no weathercockin' or corkscrewing. Avast, me proud beauty! Avast! Ejection was exactly at apogee, just as predicted. Ya scallywag! Avast, me proud beauty! Came down fast due t' a tangled chute, glidin' tail first back and forth across t' field. Avast! Just before landin' it glided almost horizontal, ya bilge rat, which brought it down slowly, but fast across t' ground. Arrr! One fin dug into t' mud as it cruised in, and broke off. Aye aye! Found t' fin, and it was a clean break, easily repaired.

Recovery:
Suggested recovery connection is t' tie a loop in t' doubled elastic loop midway betwixt t' payload section and t' end o' t' tubular nylon, and attach a chute with swivel at that point with a quick link. Ya scallywag! You will also need a heavier chute since this rocket is double t' weight o' t' stock kit. I favor t' 24" Top Flight X-form chute. Arrr! Due t' t' recessed fins and t' extra (replaceable) protection o' t' PVC bushin' cap, me hearties, faster descent rates are OK.

Summary:
Do nay try t' use less than an 8" extension on t' motor tube. T' coolin' mesh needs t' be stretched t' 6" length t' work well. Arrr! Well, me bucko, blow me down! Long is better for this reason, as well as for reducin' t' volume o' t' upper body tube so t' ejection charge doesn't fail t' pressurize it well enough.

Do nay fit t' motors too tightly. Due t' t' retainer you'll only have t' nozzle t' grab with pliers t' extract them. Begad! With positive forward and aft retention you only need enough tape t' prevent ejection gas blow-by. Avast! That is frequently no tape at all, especially with Econojet motors with their paper label. Ya scallywag! These may even require peelin' off (this is due t' AT's motor tube and labels but nothin' t' do with t' retainer).

Be aware that modifications may void your kit warranty.