Anyone built a public enemy fatboy?

[Justin]

Hey folks-
I have a Public Enemy Fatboy 4" in 29mm on the way for LDRS. I want to try for level 1 cert. with it. I found little or no real construction info on their site. Discount Rocketry (My favorite rocket shop ever!) is trying to get in touch with them to send me some info on the recovery system and fin construction. ANY advice from the forum would be greatly appreciated.

 

[Initiator001]

Originally posted by Justin
Discount Rocketry (My favorite rocket shop ever!)

Me, too!

 

[rstaff3]

I built a 3" Ultra for my L1 rocket. IIRC the instructions were brief but the rocket was fairly simple so I had no problems. You can see my review on EMRR.

 

[Justin]

Thanks guys.
Dick your review was very helpful, as was EMRR, which I had never been to. I had hoped more people
that had built Public enemy stuff would have posted here, but I think I found what I needed.

My 4" fat boy should be here by wednesday. I'll post pics of what you get and eventually stages
of construction to help out any other pre cert. guys like me.
- Justin

 

[wyldbill]

I had a buddy who built one. Thing has a TON of nose weight and flew rail straight.

 

[Justin]

Thanks Wyldbill-
I should get the kit tomarrow or day after. I'll post pics.
- Justin

 

[eugenefl]

Originally posted by rstaff3
I built a 3" Ultra for my L1 rocket. IIRC the instructions were brief but the rocket was fairly simple so I had no problems. You can see my review on EMRR.

Agreed. I built the 4" Patriot. The instructions are one page and don't include CG/CP info. The build is straightforward - 4 fins glue to the MMT. CR's "lock" the fins in place creating a fin can. Glue a third upper CR and attach shockcord screweye (or U-bolt if upgraded). Insert MMT into preslotted airframe. The Patriot comes with a payload which was my first. Very clean build. The fins are made of a multilayer aircraft grade ply with a bevel already shaped on 'em. VERY nice kit if you ask me. It was the cheapest 4" L1 bird I could find at the time.

<a href="https://www.rocketryforum.com/attachment.php?s=&postid=60651">HERE</a> it is boosting on an H123W for its first and only L1 flight. I finally got a hold of some H's and casings. Time to go H165 REDLINE baby!

All in all I think you'll enjoy the build. Post some build pics if you can.

 

[rstaff3]

My FatBoy came with a CP number and I also simmed it. Being new to HPR and nervous, I added noseweight based on the more pessimistic of the numbers. The only tricky part of the Ultra was foaming the fincan. Now that was a mess, but I was ultimately successful. Of course this added to the massive amount of nose weight I needed. Besides being short and stubby the fins are at the top of the long tail cone. But it also made it tough. On a G125 flight it flew into the chute and same down separated but with only the flutter from the edges of the chute. Only superficial paint scratches.

I still hope its remains will come down from the tree its in and someone will find it.

 

[als57]

Originally posted by Justin
Hey folks-
I have a Public Enemy Fatboy 4" in 29mm on the way for LDRS. I want to try for level 1 cert. with it. I found little or no real construction info on their site. Discount Rocketry (My favorite rocket shop ever!) is trying to get in touch with them to send me some info on the recovery system and fin construction. ANY advice from the forum would be greatly appreciated.

Strangely enough I built a 4" PE Fatboy last year with a 29mm mount. Had Ross special order it as he normally carries only the 38mm version.

Build tip 1: Add about 5oz of nose weight to it. I used lead shot and epoxy.

Build tip 2: Replace the nylon strap glued to the MMT with 5/8" tubular kevlar. Make it slightly longer than the supplied black nylon strap.

Build tip 3: Replace the round bungee cord with 12 to 15 feet of 9/16" tubular nylon.

Flew mine several times on a H128. Delay sims to about 7.5 sec. Nice whistle too.

BTW if you have the 38mm version ; it flys very well on a H148R-10. Same nose weight. I certed a couple guys L1 over the weekend ; one using the 38mm version.


Al
BRS VP
NAR L2
LDRS 23 Hosts

 

[Justin]

Thanks Al-
I did order the 38mm. An adapter in 29mm also for versatility. No one seems to like public enemy's bungee thingy. I think I'm gonna replace it with a kevlar one from giant leap.

Did those kits you saw have their cords attached with eye bolts? I don't think I want to glue it.

-Justin

 

[rstaff3]

I built the stock FB recovery system, and although it may not be the preferred solution, seemed to work fine.

 

[als57]

Originally posted by Justin
Thanks Al-
I did order the 38mm. An adapter in 29mm also for versatility. No one seems to like public enemy's bungee thingy. I think I'm gonna replace it with a kevlar one from giant leap.

Did those kits you saw have their cords attached with eye bolts? I don't think I want to glue it.

-Justin

I'm sure the bungee thing probably works fine ; I just got turned off by elastic things in LOC kits sometime ago.

Pretty sure it did the glue thing. Simular to the PML kits. Was looking at my Extreme Performer MMT and its that way. Was hoping to have it done for LDRS ; but it doesn't look good.

For the 38mm mount make sure you add the nose weight I recomended. A H123-10 or H148-10 should give you a good flight.

If your going to LDRS ; maybe I'll see you there. Unfortunately I have to work.

Al
BRS VP
LDRS 23 Hosts

 

[Justin]

Al-
I'll try to track you down at LDRS. Hopefully you won't be running the whole time and will get to fly some.

Now I have to figure out the hard stuff. Where to get motor casings and what kind to get. I'm thinking aerotech and pro 38 as starts, mainly 'cause they work with slimline retainers.

I guess I'm allowed to buy one H to certify? I want to track down some smaller 38 & 29mm motors too to get some flights in on this bird at LDRS. I have a pile of little stuff to fly too.

I'm still waiting for this kit to arrive. It's been 6 whole days! Gettin antsey.....

 

[als57]

Originally posted by Justin
Al-
I'll try to track you down at LDRS. Hopefully you won't be running the whole time and will get to fly some.

Now I have to figure out the hard stuff. Where to get motor casings and what kind to get. I'm thinking aerotech and pro 38 as starts, mainly 'cause they work with slimline retainers.

I guess I'm allowed to buy one H to certify? I want to track down some smaller 38 & 29mm motors too to get some flights in on this bird at LDRS. I have a pile of little stuff to fly too.

I'm still waiting for this kit to arrive. It's been 6 whole days! Gettin antsey.....

Got to say the Pro38's are really easy to cert with. I used an AT for L1 and a Pro38 for L2. Pro38 casings are cheaper and easier to use. Reloads are more expensive. If you have no experiance with reloads ; then the Pro38 is the way to go. Buy a 2 grain case and DAT.

Mangum and Performance Hobbies will both be there so motors should not be an issue.

Hope to see you there.

Al
BRS VP
LDRS 23 Hosts

 

[Justin]

The 4" fatboy landed. Here's what you get:

-1 pre slotted 4" airframe, already marked for the lug and everything. It also has some sort of shiney covering to make it smooth.

-1 hefty V2ish nosecone with a think molded loop thingy for attachment. It's finish is a little rough, but it looks sturdy as hell.

-4 1/4" inch fins already beveled to a 45 degree angle(really nice)

-1 38mm motor tube

-3 particle board centering rings, one of them slotted to pass through the shock cord.

-1 30" rip stop chute with a welded ring and a quick link (mine came orange)

-1 15' 1/2" nylon shock cord in florescent orange (very bright)

-2 beveled copper launch lugs. 3/8ths I think.

-one vynyl fatboy sticker

-2 pages of written instructions with 1 diagram

A lot of cool stuff for only 54 bucks. I'll post a pic of the pile if I can get Graphic Converter to work. I can't seem to get pictures small enough to post..

-

 

[Justin]

I'm the worst digital photographer in the world. I can't figure this thing out. More on Mac photo trauma later....

I built the Fatboy fins and motor mount. I must say I am really impressed. Simple and solid. Like I mentioned befor, I'm a low power guy, so I had a couple pitfalls in the land of 30 minute epoxy. I really can't wait to fly this thing..

 

[Justin]

Here goes-

 

[Justin]

I wanted to show the kit in pieces, but I couldn't wait to build. Here's a closer-up of the fin section.

Like I said, I'm new to epoxy..It went everywhere. You can see the cool orange shock cord taped there. I guess they don't use the bungee thingy any more.

 

[Justin]

They (public enemy) pre score the tube for you. You just gotta slice the strips out. I reccomend cutting the tops of the slots to match the 45 degree angles of the fins. Maybe evryone already does this, but it's my first biggie.

Someone on the forum or EMRR suggested saving the tube scraps to fill the space behind the fins in the slots after assembly. THANKS. Never would have thought of that.

 

[Justin]

Here's the heavy duty nose cone. I'm gonna chop off the little piece of flash, and dump in the reccomended 5 oz of weight. Probally fishing weight and epoxy. I think the cone is thick enough not to have to have the tip of it in ice water to prevent warping.

 

[Adam Selene]

Originally posted by Justin
Here's the heavy duty nose cone. I'm gonna chop off the little piece of flash, and dump in the reccomended 5 oz of weight. Probally fishing weight and epoxy. I think the cone is thick enough not to have to have the tip of it in ice water to prevent warping.

you might want to add about 8 oz of nose weight, just to make up for all that epoxy you've got on the motor mount. just messin with ya dude, it's been too long since i could abuse you in person that i just had to abuse you in public. don't stress, level one is way easier than nartrek bronze gorilla launching from softball fields! can't wait to see it fly!

btw- the roving rocketeers are looking for 3 more members, just in case anybody out there needs friends to abuse them too!

btw- glad to see that you figured out the graphic converter thing! without any help even

 

[Adam Selene]

i'm such a :kill: , somebody should slap me.

 

[Justin]

With that much epoxy I bet I could just sand out the cardboard and fly with a transparent motor mount!

 

[als57]

Originally posted by Justin
Here's the heavy duty nose cone. I'm gonna chop off the little piece of flash, and dump in the reccomended 5 oz of weight. Probally fishing weight and epoxy. I think the cone is thick enough not to have to have the tip of it in ice water to prevent warping.

You may want to keep the nose cone in a bucket of cold water just in case. Mine got a bit warm when the epoxy cured. Ice really not needed ; just cold water. Don't know if it was enough to melt things ; but why take the chance?


Al
BRS VP
LDRS 23 Hosts

 

[Justin]

Thanks once again Al-
I'll do that. Why take the chance, your right.

I forgot to post this befor. Here's a pic of the diagram that comes with the kit. You can't really see it, but they give simple instructions and CP & CG data.

 

[Karl]

Very nice , keep it up ! Have you decided what colour to paint her yet?
Karl

 

[Justin]

I'm thinking rust-o-leum metallic blue with a bright red nose cone and fins (metallic maybe), and a black stripe down the middle to show off the silver vynyl FatBoy decal...Not sure yet. You guys wil be the first to see. Except for my extremely tolerent girlfriend who hopefully won't dump me for playing with spaceships all the time .

 

[Justin]

I'm almost ready to throw the Fatboy together, when a thought popped into my melon. Do I sanding seal the fins before or after the the epoxy fillets. The sanding sealer I have is made for RC airplanes and is nasty smelly stuff. Paint thinner won't clean it up, I've had to use the the thinner made by Aerogloss. Nail polish remover worked too. So (the point finally), will my sanding sealer eat away the epoxy? Any help would be cool...

 

[Karl]

There is a problem here........If you put the sanding sealer on before you epoxy the fins in , the epoxy might ONLY stick to the sanding sealer and not the wood , making it weaker. But you could epoxy the fins on without putting it on , do the fillet then mask off the fillet and be REALY carefull with a old paintbrush.
You could always test it , mix a small ammount of Epoxy onto a peice of paper/card/wood what ever , let it cure , paint over it with sanding sealer , and see if it weakens it?
-Karl

 

[Justin]

The fins will be plenty strong I think, as the only area affected by the sealer would be the actual slots in the tube. The motormount/fincan is pretty rock solid, and will be mostly held in by internal epoxy and top and bottom fillets on the CR's.

I was thinking from a finishing standpoint. Will the epoxy on the outside become a slimey mess if I seal the fins after assembly?

You're right Karl. A test is in order...