Simon's 18" Balsa cat

[Simon.O.]

I am now building two cats at once and the build logs will be similar for the first few posts and then naturally there will be variations in the build that needs a separate thread thus we have two new balsa cat threads.

This is a scaled down version of my bigger Cat and should work out well, There are no plans at all and both of these two new ones are being built by eye with a few rough scetches on a pad on the wall.

I will announce the power setup as soon as I have chosen one !!

As it is common practice to measure a Cat from the rear of the last step this counts as a 18" There is a good rear overhang and the the strut will be aft of that too.

Some pics for now.

[Simon.O.]

Power setup is now chosen.

Motor

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6262

ESC

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=10015

Packs

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=10290

Prop
X432 Octura

This will be a 2P stup as the packs are small.

The foaming "Gorilla-Glue" That I am using is a bit messy but very strong.
I am confident that this and the 13" hull will clean up well even before I paint them.

A couple of pics from today. The Hardwood for the strut mount is there and I am now ready to foam fill the sponsons prior to decking.

[ED66677]

Another nice pair of built Simon!!!
have you ever thought to build a cat hull, and especially the sponsons in a simpler way... instead of building the entire structure out of wood and fill with foam, do it the other way round, shape foam (hot wire cutting and sanding) and then form wood all around? you would need less wood! this is just a thought from the time I was building giant RC plane, that's how I was making wings!

[crabstick]

cool boat Simon, is it going to be a 3 point like the baby freya or are you adding ridepads later?

[Simon.O.]

ED I had considered building a wood over foam (WOF) as it was suggested by Paul here (NativePaul).
It would cost me as much to drive somewhere to get the good blue foam as it would to do it this way.
Weight is not an issue now that I run BL+Lipo in the wooden hulls, in fact most of the hulls I run have lead ballast !!

This hull as with the smaller 13" have a few build ideas that are proven. The spray foam is a new thing for me and I'll see how that pans out.

I have not lost a hull yet, I have rooted a few and one is now a museum piece but I have always recovered a hull

A 26" twin is on the paper now !!

[blackcat26]

Looks good bro! I like the inner-workings, much simpler than some that I have seen and still looks good and sturdy.

[Simon.O.]

I was off to cut a doorway in a solid cast concrete wall yesterday so decided to foam fill the 2 cat hulls before I left. I came home and near wet myself laughing at the mess.

Well a bit of cutting and sanding today got me this.
I have most of the decking on and will start on the hardware soon.

This one looks a bit tall in the hull to be a real beauty but it is what I have.
I cut a piece of card to show a possible canopy shape too.

A few pics for you all.

[CornelP]

With this shape it will be a case of "Wait till the fat lady sings!!!"... beautiful as always.




cl # 2 = ONLY

[crabstick]

Rofl, looks like they got Elephantitis in the first pic

[blackcat26]

I see pic number 2 has some boating fluid sitting there on the right.....Right on brother!

[ED66677]

yeah that's where the foam comes from!

[Simon.O.]

I see pic number 2 has some boating fluid sitting there on the right.....Right on brother!

That is a very special fluid that I dip my pencil in when I draw up one of these hulls.
It needs to be emptied and then refilled after each dip
Luckily I also have a fairly extensive refill supply as I make it right here.

BTW That foam is some sticky stuff before it cures.

[blackcat26]

I have used 2 part polyurethane foam with good results also. That stuff is so bad after it cures. Actually adds rigidity along with it's waterproof ability.

[Simon.O.]

The bottom getting close to ready
This will be a very similar shape bottom to the cat that died a few weeks ago due to excessive speed and lack of strength. (that one was built for brushed cans)

There are no steps at the moment and I hope that I can get away without them, I can always cut/sand them in later.

The decking is 90% there and now that I have the power system I can setup the inside and the rear.

The power system is:
450 size Heli motor 3850kv with a possible power output of 450+Watts
Esc is 70-80A with Bec
Packs are 1800mAh 40-50C which are good for 72-90A, in a 2P setup I will have a lot of headroom here.

This setup will allow me to feed in a bigger motor if I have to. We'll see !!

I think I will shorten a lot of wires yet before the connectors go on.
I will run 4mm gold bullets all round here as I have run 4mm in higher amp setups with happiness.

Pics from today

[Simon.O.]

A bit more progress, curing the balsa sealer in the cold weather takes time and I have other things to do as well.
Hatch is now made.
Motor is mounted.
Stuff tube and servo mount are now in.
The transom hardware for this hull is taken from the old 25" cat that died but is now on a shelf.


To do:
Sand and seal more and then varnish.
Finish the steering linkage. This is made from parts taken from another shelf filler, the old hydro.

I think two more weeks and this will hit the pond !!