12" scratch built cat

[Jesse J]

Ok, I'll see about working with Bill on getting some drawn up...

[Dr. Jet]

Ok, I'll see about working with Bill on getting some drawn up...

I've started some drawings for a 16" version for laser-cutting. There's actually a LOT of work that goes into the drawing; making certain everything lines up, fine-tuning some things that weren't laser-perfect in the original files, making allowances for the cutting kerf, and so on.

Gotta finish the Atlas first though......

This strut/rudder should just barely fit: https://www.ebay.com/itm/Rudder-with...19.m1438.l2649

[Dr. Jet]

Hmmmm..... Twin motors will fit in the 16" version.....

[Jesse J]

Whew.. I not so keen on lil bitty motors in sponsons I can't git to...
In my 34" version, ees ok. But in this lil guy... me not so shore.

[Dr. Jet]

Whew.. I not so keen on lil bitty motors in sponsons I can't git to...
In my 34" version, ees ok. But in this lil guy... me not so shore.

It's not as bad as it seems. See my thread on the BBY Micro Scat Cat Twin. The BBY MSC is a HOOT and it hauls a$$!! Yeah, it's a b.....itch to get to the motor mounting screws, but I have a plan to make it easier to mount the motors in the laser-cut kit........

[Dr. Jet]

I keep tinkering on the drawings and I keep seeing things that don't fit right... Whew!! I think Jesse had an issue where the sides transition to the transom. I think I have that solved, but every time I changed one thing, it affected three other things things.

As for power, this one WILL NOT be a twin. I plan to use a long-can 3800 Kv helicopter outrunner in it. Easy access to all parts on this one.

[Jesse J]

I keep tinkering on the drawings and I keep seeing things that don't fit right... Whew!! I think Jesse had an issue where the sides transition to the transom. I think I have that solved, but every time I changed one thing, it affected three other things things.

As for power, this one WILL NOT be a twin. I plan to use a long-can 3800 Kv helicopter outrunner in it. Easy access to all parts on this one.

Dang Bill! I drafted these plans up with the intention of printing, cutting out the parts, paper gluing them to the wood and cutting at the band saw... you are taking the precision to a whole new level.

[Dr. Jet]

Dang Bill! ... you are taking the precision to a whole new level.

I guess that's the engineer in me. I used to design roads and bridges (among other things). A hundredth of a foot off in one area could mean hundreds of thousands of dollars in another.

I'm still debating on whether or not to laser cut the sides. It will make building the steps a whole lot easier, but the compound curves are beyond a bitch to work out. I think I have the math and geometry worked out and I've done some paper cut-outs to confirm my assumptions. My plan is to use 1/32 ply for the skins and the sides will wrap around to the transom. It would look something like the attached sketch, but I may have the angles of dangle WAY off.

[Dr. Jet]

Problem solved! After watching the video of the 12" cat run, it seems that the steps in the hull that I copied from the larger version really aren't that necessary in the mini-sized one, so I simply eliminated them. In so doing, I'm going to leave it up to the builder to #1: Supply the skin material (1/32 ply), and #2: Cut all pieces to fit.

[Dr. Jet]

Well, I think I have the plans done enough to cut a prototype. I made all the linework as polylines so I could offset them the required 0.002" to account for the cutting kerf. As you can see from the attached screenshots, there's a lot of tab and slot construction. This makes it easy to line everything up and keep everything square.

This will have to wait until I'm done with the Atlas and the Casper, but the hard part is done now.

[Jesse J]

Did you get the small 12" plans? There is no step in that one.
Looks like you are making progress and adding a motor mount, nice touch.

[Dr. Jet]

Did you get the small 12" plans? There is no step in that one.
Looks like you are making progress and adding a motor mount, nice touch.

I think you just sent the 24" plans. That's OK, it's real easy to cut the steps off. Now, I have to find an uber-cool way to make the strakes.

[Jesse J]

For every one of these, I have added the strakes after skinning the bottom, and used trailing edge balsa... probably not in the Uber-cool category.
Another way, likely still not in the UC club, make a vertical former that locks into the bulkheads at the outside of the strake, then add a flat strip between that and the inner former to make a ride pad?

[Dr. Jet]

I have a table saw and I'm thinking I could use some hardwood and by making multiple passes with the blade vertical and angled, cut some strips that resemble really small aileron stock. The hardwood should result in really sharp edges. Next time I go to Home Depot, I'll check out what material they stock.

[NativePaul]

Plastruct L section come in many sizes and works well for stakes.