Skunkworks Mach5 30" Cat Build

[FE_Chris]

Hey guys. I am building this Skunkworks cat to race in the SSLSO class with our club this year. I have not gotten very far. I installed the hardware tonight so I really am just getting started. I got my order from Steven today so I almost have everything I need

I do have a question. The two pics of the strut (1st pic and last pic) I took are differant, if you look I have the strut moved UP all the way in one pic, and moved all the way DOWN in the other. I wanted to know if you people thaught that I had enough ajustment in there. It's mounted up now so I hope so!

Also, anyone know the CG in the boat?

I need to get a tube bender....then I can get this build moving along....

This is gonna be the setup

SW's 30" Cat Hull
Mach 5 Inline hardware .150 cable
ProBoat BJ26 Brushless Motor
Hydra 120 ESC
4s1p PQ lipo

Im hoping for 40 MPH and WOT turning. :-)

[obrien]

Sorry this is a bit off topic, but what does LSO mean?

[domwilson]

I have one. It has a Feigao 9XL, Hex 120 and aeromarine hardware and a x637 prop. Here are some pics. It's faster than my SV27 with a X642 on lipos.

[FE_Chris]

Limited Spec offshore. We call is SS or Super Sport cause instead of brushed 700's we are using SV27/PB brushless motors.

Thanks for the pics....Damn your strut looks high! I guess the good thing is, if I set mine a little to low, I can always trim a little off to move it upward.

How do you like the handling of the SW's Cat?

[obrien]

what hulls are allowed in that class?

[domwilson]

It turns real good like its on rails. Planes really nicely. I like it. The strut is up high because these have a tendency to porpoise. I'm going to install a 8XL, hydra 120 and a X640 in the next week. Probably won't get to run it or my other boats for the next few weeks, but it is definitely my favorite boat.

[Fluid]

I need to get a tube bender....then I can get this build moving along....

What do you need a tubing bender for? Certainly not for the stuffing tube! You can bend K&S brass tubing very well with your hands, just go slow and have the piece longer than you need, cut it to length later. I just got finished bending a new stuffing tube for my 10S catamaran - its 5/16" diameter brass and if I can bend that by hand (it was easy!), then you can bend smaller tubing just fine. I can bend 1/8" tubing into a 3" diameter circle by hand with no crimping or collapse.

DO NOT ANNEAL THE K&S TUBING! I do not know where this old wives' tale came from but it is BS. It bends just fine as it comes off the rack. If you do anneal it - it will be too soft and the cable or wire will not be well supported. And don't bother filling the tubing with sand or sugar or anything - it bends fine without collapsing. Just go slow and make gradual bends.


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[domwilson]

Fluid is right. You should be able to bend K&S by hand as long as the bends aren't too great. If you are worried about it collapsing, put the telflon and the flex in it before attempting to bend.

[Diegoboy]

Fluid is right. You should be able to bend K&S by hand as long as the bends aren't too great. If you are worried about it collapsing, put the telflon and the flex in it before attempting to bend.

Fluid is always right, but inserting the liner and shaft will prevent collapse, but don't think it'll guarantee a usable tube. I tried that, it didn't collapse, but the kink was enough that pulling the cable out was tight! Needless to say, I couldn't use that tube and had to try again.

[SJFE]

I have a bender & Iv'e ruined 2 feet of tubing so far. When I get more this afternoon ima do it by hand.

[FE_Chris]

Thanks guys you are right about the tube being easy to bend! Cause I think I am ready to glue and glass this bad boy in I want you to check the pics, I think it looks good but I wanna make sure.

I have the teflon tube running into the strut. The brass tube is right up next to it, I am going to move it away 1 mm and shrink wrap it up.

Also, as far as epoxying the stuffing tube in......I was thinking I would use some small pieces of fibre glass cloth AND epoxy. Thats a big hole to fill it looks like epoxy will just run right out!

Im gonna wait for some replys before I procede.

Also, I was gonna glue the tube....THEN glue the motor mount with motor and flex cable/collet installed that way EVERYTHING is lined up all nice and perfect. Well, actually, I would like to set the mount like this with some epoxy, then remove the motor so I have room to work and start glassing it on real good with the cloth and whatnot.

How's that sound?

[FE_Chris]

Thanks dom. I guess i'll start with the strut all the way up when I go to test and lower it as I see fit. Looks like you have your batterys quite far back in the boat too.....COG needs them that far back?

Looks good man!

It turns real good like its on rails. Planes really nicely. I like it. The strut is up high because these have a tendency to porpoise. I'm going to install a 8XL, hydra 120 and a X640 in the next week. Probably won't get to run it or my other boats for the next few weeks, but it is definitely my favorite boat.

[domwilson]

I had them further forward and it ran too low in the water. With Lipos, it seemed to run better there. Chris at Fine Design recommended thats where I should start. He was right. As far as the stuffing tube. Maybe some electrical tape on the underside might work to prevent the epoxy from "bleeding" thru. Maybe someone has a better idea?

[Fluid]

I have the teflon tube running into the strut. The brass tube is right up next to it, I am going to move it away 1 mm and shrink wrap it up.

I don't use the teflon, haven't for about ten years. But it is fine to do so, just remember you still have to use a good lube.

Also, as far as epoxying the stuffing tube in......I was thinking I would use some small pieces of fibre glass cloth AND epoxy. Thats a big hole to fill it looks like epoxy will just run right out!

I always put pieces of tape on the underside of the hull to keep the epoxy from running out. A few pieces of cloth are a good idea too, or use something like MarineTex or JB Weld.

Also, I was gonna glue the tube....THEN glue the motor mount with motor and flex cable/collet installed that way EVERYTHING is lined up all nice and perfect.

I usually mount the motor first, then move the stuffing tube around so that there is a perfect alignment between the drive cable and the motor....but I have done it both ways. Use whichever you feel most comfortable with, but just make sure the alignment is perfect. Sometimes I take an hour or more moving the motor or tube around, cutting the hole bigger if needed, until everything is just right. It makes a difference in the final performance of the boat and the life of the driveline.

Fluid is always right...

Not hardly - but I have made enough mistakes and seen enough mistakes over the years to know what usually does not work best. :blushing: If the K&S tubing kinks, then you are trying to bend it too sharply. Use both hands and your thumbs to make the bends. I have bent enough tubung over the years - many many dozens - to know that the method works well without anything inside the tube when you bend it.



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[FE_Chris]

Thanks fluid! I went ahead and grew a set, and epoxyed this bad boy in. I used a few pieces of cloth as shown on top, and I did so on the bottom too, just not as much. The epoxy is quite thick, and although it does run through the hole it's not a huge issue now with the cloth.

I have everything lined up pretty good. I am more comfortable doing things this way for sure.

Thanks guys. More to come....Im gonna have to finish the epoxy on the bottom later, than after that dries I am gonna do the mount. seeya!