Modification Fat Boy - 24mm Modification

Modification - Fat Boy - 24mm

Contributed by Colin Westgarth-Taylor

Manufacturer: Modification

(MODS) Estes Fat Boy with 24mm MMT

Brief:
An Estes Fat Boy modified with a 24mm MMT for D and E motors. Well, blow me down! Begad! External dimensions are stock. These modifications change one o' Estes best packaged kits into a true performer.

Modifications:
Construction sequence be pretty normal for a MPR capable rocket: forward CR epoxied t' t' MMT, matey, shock cord mount epoxied t' t' MMT (two 1/32" holes were drilled in t' front CR t' tie t' Keelhaul®©™ cord to), me bucko, epoxy MMT assembly into t' body tube at t' front rin' only. Avast! T' aft rin' is just thar t' locate t' motor tube and can be removed by means o' clear tape. Avast, me proud beauty! Ahoy! Fins saw a coat o' thinned white glue and Elmer's Fill 'n' Finish prior t' bein' installed. Begad! T' root side o' t' fins were sanded down very slightly t' allow for a proper fit with t' larger motor tube. Well, blow me down! After epoxyin' t' fins t' t' motor tube, t' aft rin' is removed and internal filletin' is done (rear CR had small groove cut on t' inside rin' with 3/16" drill bit t' allow movement o' t' "E" engine hook), me bucko, then t' aft rin' is epoxied on and external fin fillets are done. Arrr! All assembly used 5-minute epoxy.

Construction:
After openin' t' package, shiver me timbers, I examined t' parts and decided on makin' some upgrades. Ahoy! T' stock 18mm motor tube was swapped out for a 24mm motor tube 4" in length, matey, t' paper centerin' rings were swapped out for 1/8" ply centerin' rings, t' stock engine hook be swapped out for an "E" length engine hook. Aye aye! A 24mm thrust rin' be added t' be sure t' motor stays in place while under thrust. A brass 3/16" launch lug was added for (MODS) Estes Fat Boy with 24mm MMTincreased durability. Begad! Keelhaul®©™ cord (120lb) was added t' t' kit t' make a strong anchor point for t' shock cord (~18"). Begad! A Keelhaul®©™ sheathed elastic cord was added t' make a durable shock cord (~48"). Well, blow me down! And finally t' stock Estes plastic chute was swapped out for an 18" ripstop nylon chute with a swivel. Everythin' else needed t' complete t' build came directly from t' Estes Fat Boy kit (i.e., me bucko, nose cone, arrr, body tube, arrr, fins, decals).

T' Fat Boy does come well packaged and all parts were accounted for (although most were nay used). Blimey! No parts were broken although it should be noted that t' nose cone in this kit required a "considerable" amount o' sandin' for it t' slide into t' body tube properly. Aye aye! T' materials supplied are pretty much Estes standard: paper tubes, balsa fins, and plastic nose cone. Begad! T' instructions and illustrations were very easy t' follow so much so that this kit would be well suited t' a first timer. Begad! Arrr! Blimey! It should also be noted that t' help guarantee perfect fin alignment, an Estes fin alignment guide be used durin' construction.

(MODS) Estes Fat Boy with 24mm MMT

Finishing:
After primin' with a Krylon white primer it was decided t' use Krylon True Blue Gloss for t' body tube and Krylon Sun Yellow Gloss for both t' fins and nose cone. Stock decals were applied and a few coats o' Tremclad clear coat were laid down. Begad! Finally t' bottom side o' t' aft CR was covered with a small piece o' 322 silver foil tape for nothin' more than cosmetics. Avast, me proud beauty! Avast! (C'mon it's a chrome aft end!)!

Flight and Recovery:
Prior t' flyin' this modified Fat Boy approximately 1 1/8 oz. o' nose cone weight was added in t' form o' #8 shot. Avast! It was held in at t' tip o' t' nose cone with 30 minute epoxy. Avast, me proud beauty! An Estes D12-3 motor was selected for t' first flight. Ahoy! Avast! This engine had simmed it t' a safe altitude o' 460 feet. Arrr! T' rocket was prepped with an "E" engine space block t' allow t' "D" engine t' fit properly. Blimey! A mixture o' Estes waddin' and cellulose be used. Begad! Aye aye! T' engine is retained with t' metal engine hook. Avast! T' flight be very impressive but more impressive was t' fact that t' Fat Boy flew perfectly straight with no twistin' or (MODS) Estes Fat Boy with 24mm MMTarching. Perhaps that be due t' t' fin alignment guide? Deployment happened right at apogee and allowed t' 18" chute t' safely brin' t' Fat Boy down for an easy recovery approximately 30 feet from t' launch pad. T' next launch be on an Estes E9-4 and proved t' be even more impressive. Aye aye! I placed t' loaded rocket on t' scale just prior t' launch and it read 7.5 oz. Arrr! Well, blow me down! T' rocket tracked perfectly through t' air this time as well as it raced upwards t' somewhere around 1000 feet. Ejection was at apogee and recovery was successful with just a short walk (~100 ft.). After inspection o' t' rocket everythin' be in tact and t' project was labeled a success!

Summary:
This is a super little kit from Estes and a prime candidate for you t' add your own unique modifications to. Avast, me proud beauty! Ya scallywag! I was inspired t' modify this kit after seein' others fly t' stock 18mm version on Bs and Cs with less than stellar results. T' main PROs o' this kit has t' be its ease o' construction and t' endless possibilities for modifications. Blimey! T' only CONs I can think o' are t' usual Estes "moans and groans": t' stock shock cord is far too flimsy and short and that t' stock plastic chute which will nay last long.

Other Reviews
  • Modification Fat Boy - 24mm By Morgan Hendry

    This project begun when I read several posts from rec.model.rockets on placing a 24mm motor mount in a Fat Boy, normally a 18mm kit. I first looked at the instructions and made a list of what I needed to do. Replace the 18mm motor tube with a 24mm one Make bigger motor mount with modified centering rings (higher strength) and an engine block Remove some of the "through the wall tab" ...

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