Estes Fat Boy 29mm rebuild.

[Back_at_it]

A couple of weeks back I picked up a nice used Estes Fat Boy from another member with the sole intention of rebuilding it to fly on 29mm motors.

The rocket was in nice shape overall and a good candidate for the project. Due to the altitude I'm planning to use streamer recovery so I'll be beefing up parts along the way to survive the flight and the landing.

Here the rocket I started with. It was a nicely built but well used Fat Boy.



First step came disassembly. With a little sanding of the paint and scoring the glue with a hobby knife, hot water was applied to the glue joints and the rocket pretty much just pulled apart.




Here are the parts we're going to use to rebuild.

- Stock nose cone. The bottom has been removed as I'm going to need all of the room I can get inside the body tube for recovery gear.
- Bulk head for the nose cone with a couple of piece of scrap use use as backers.
- Rear Centering ring made from card stock.
- Upper ring made of 1/8" plywood with a piece of scrap for a backer for the chock cord attachment point.
- Stock BT80 body tube.
- BT80 Coupler cut 1 inch shorter than the body tube to allow room for the nose cone shoulder.
- Original Balsa fins and the some file folder material cut to shape to paper the fins.
- 29mm motor retainer.
- 29mm motor tube.



Assembly began with inserting the coupler into the tube. I used epoxy for this as the fin slots were already cut and I wanted the ability to move the couple to align the slots with the tube. Epoxy was spread inside the tube and on the outside of the coupler.








With the main body curing I began work on the motor mount. The areas where the rings, motor retainer and fins will attached have all been sanded to allow the epoxy to penetrate the materials.



The motor block was inserted into the motor tube then the upper ring was attached. After letting that cure, I added a piece of 500# Kevlar for the attachment point for the recovery system.



After letting everything cure for a day I inserted the motor mount into the body tube and set that aside to dry for a day.




I'm working on papering the fins today so we'll get those attached in the next update.

 

[Back_at_it]

With this being a used rocket the body tube had a few blemishes that I felt would be easier to deal with before the fins were installed. I did a little more sanding to get some of the old paint off before taping off the areas where the fins will attach then shot on a couple of coats of high build primer. Afterwards there was a little filler work do to make things smooth.



Next up was papering the fins. I once again used file folders to paper the fins. As you can see from this pic, the fins are less than perfect with the tips taking the brunt of the damage. The folder materials was attached using T-88 epoxy.



Once all three were papered and cured they were rough sanded with 320 grit before applying a coat of wood filler. The wood filler was sanded smooth.



Fins were attached using more T-88 epoxy.






3/16" launch lug was attached.




Next update will be internal and external fillets and the rear centering ring.

 

[Back_at_it]

Internal fillets have been applied using T-88 epoxy and left to harden for a few hours.



Next up was the external fillets. More T-88 Epoxy



Finally it was time for the rear ring. Since this ring doesn't really do anything I simply glued it in place with TBII wood glue.

 

[Hobie1dog]

that ought to be one tough rocket

 

[cwbullet]

Great build thread. This is one of my favorite kits. Balsa will take the 29mm motors.

 

[86mustang408w]

Nice! Do they use the same nosecone as the SBB?

 

[Back_at_it]

Nice! Do they use the same nosecone as the SBB?

Yes. Exact same nose cone

 

[86mustang408w]

Yes. Exact same nose cone

Ok, I was curious. My SBB recently had a bad time and I rebuilt the nosecone with a coupler, I didn't realize they use them too. Thank you.

 

[Back_at_it]

Time to wrap this one up.

While wandering the isles at Hobby Lobby I stopped by the paint section and picked up two cans of Krylon Glitter Blast paint. one can of blue and another they call starry night (Black). The main body was painted with the blue color. You absolutely must shake this stuff for a few minutes to get it to come out correctly. This is after three coats.

The paint has a texture to it. I wouldn't call it rough but it's not smooth either. This will defiantly be getting a coat of clear to smooth things out and keep the glitter from coming off when handling.

The nose cone was painted with the Starry Night color.



Next it was time for the motor retainer. The motor tube was sanded to remove any glue that might have gotten on there during assembly. The rear ring was painted black for ascetics. The inside of the motor retainer was sanded with a 40 grit roll to give it some texture for the epoxy to adhered to. The retainer was attached using T-88 epoxy.



While the retainer cured, I worked on the bulkhead. I know this rocket will need nose weight so I'm not concerned with adding weight up top. I sandwiched two pieces of plywood together using epoxy to create a bulkhead. A screw eye was attached and set aside to cure.



After letting everything cure. I loaded up the rocket with all the recovery gear and the largest motor I intended to use and took some measurements for CG. Plugging everything into open rocket I determined that I needed 1.5oz of nose weight. The inside of the nose cone was then roughed up with a sanding roll, cleaned and left to dry. 1.5oz if BB's and epoxy was added to the tip of the cone.



Not pictured. I used some expanding foam to fill the remaining void in the nose cone to keep the nose weight from moving. The bulkhead was then attached using more T-88 epoxy and left to cure.



Up next was attaching the shock cord. The cord is 8ft of tubular Kevlar. This was attached to the Kevlar leader and tied off the screw eye in the nose cone.



Rocket was finally assembled.




After spraying on a couple of coats of Duplicolor clear, I weighted the finished rocket. With all recovery gear but no motor, we're at 8.8oz. The center of gravity of at the 7.0" mark which is a little more than 1/4" further forward than my proven 24mm version of this this kit so this should fly well.



When I first started kicking around this idea, I wanted to fly this on the Estes D12 and E12 motors for small parks. I'd hoped to keep it light enough to fly on the F15 but that motor has such power performance off the pad that it was hard to keep this weight light enough. I was ultimately targeting the Aerotech F32 and F67 motors for the higher flights and I think I accomplished that goal. This will still be safe on calm days on the D12 and E12 but will fly nicely on pretty much any Aerotech 24 or 29 mm I can think of.




Thanks a wrap!!

 

[Back_at_it]

We getting a little bit of sun today so I thought I'd grab some pics outside. The glitter in this is amazing.

 

[COSTransplant]

Really turned out great -- nice job! I have one sitting on my desk here that I got the same way that I am going to "rebuild" as well.

 

[cwbullet]

I do like the paint job.

 

[86mustang408w]

I like the Rocket, and Foxbody....

 

[Back_at_it]

Got three flights on it this weekend. Flew prefect on a D12-3 and an E12-4. Then I went big and tried the F67. Results we're great as it took off at about a 45 degree angle but it did go up about 600 ft. Plenty high enough that nothing was in danger and the ejection had plenty of time to fire. Recovered safely but it was a darn long walk.

I have a few of those nose cones laying around including a few that are pretty beat up. I'm going to add some additional nose weight and try again at our next launch. I will make this work


View attachment Launch_10-22-23_FatBoy29_F67-6.MOV

 

[RobertH3]

I have the parts and am going to build one. I absolutely love my Quark upscale to 2.6/29mm.
It's my veteran/ace at 26 flights. Smaller 2.6" or 3" mid-power models are resilient if lightweight.
This should be better for smaller 29's, especially slow burners like F20W and F25W

Cheers / Robert