Tell me about ride pads and angle of attack

[hughb]

Hi guys,

I've got a Mean Machine that I've blueprinted the ride pads. To even everything out I had to take off a fair amount of material, and would like to build the ride pads back up with 1.5mm G10 plate. This will also ensure there will be sharp 90 degree angles on the edges.

Now to the angle of attack of the ride pads. What would be the optimal angle. Most cats seem to have just a minimal amount?

[Jesse J]

Do you mean on each step or the front half?
Any pics and annotation will help.

[hughb]

I was mainly meaning AoA on the ride pads.

I have glued in small strips of G10 on the rear of each ride pad, and with a light sand on a stone benchtop, now have the boat sitting flat and level. Below you will see the bottom of the hull with the small black strips:

20210315_121534_resized.jpg

I've cut up some G10 plate that I'm planning to use as the ride pad surface. Here is some pics of 2 of the plates resting on the middle and rear pad. The plates have masking tape on them currently as I still have to cut them narrower. Also is a pic of the AoA this will make on the pads. The gap I was planning to glue in some balsa and sand down to match the strips already glued in, before gluing the ride pads on (and blending them in with marine epoxy filler):

20210315_121619_resized.jpg


20210315_121701_resized.jpg

For the front ride pads, I've cut some plate much longer to cover their whole length. This is in the below photo, though obviously I haven't yet cut them to the triangular shape.

20210315_121808_resized.jpg

[hughb]

Alternatively for the front ride pad, should I use a shorter pad, similar to the middle and rear pads, as shown below:

Attachment 172188

It's probably much ado about nothing, but I'd like to make the pads as accurate and true as possible.

Also for attaching the ride pads, I was thinking of drilling several small holes into the existing pads beforehand. This way when I glue the new pads on the epoxy will flow into these holes providing an extra "key" to hold them on securely. Do this sound like a good idea?

[hughb]

I've glued on the new ride pads. First photo shows the electrical tape to protect the surrounding surface from the epoxy, and the holes drilled.

20210316_122018_resized.jpg

This one shows all ride pads fitted.

20210316_130326_resized.jpg

And this final one shows the AoA of each of the steps.

20210316_125941_resized.jpg

It appears the rear steps have slightly more AoA compared to the middle and front. I was reading an old thread about Darrin's Cheetah build and it mentions that some Cheetahs have increased AoA on the rear steps that can act as a trim tab and keep the bow down. I'll keep it as is for now, just need to fair everything in with epoxy paste.

[Mike W]

Nice work! ~2.5 - 3 degrees is common on a cat.

[Fluid]

It is nice, but unfortunately the OP hasn’t been back to the forum in over six months. He won’t see your appreciative post.



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[Mike W]

It is nice, but unfortunately the OP hasn?t been back to the forum in over six months. He won?t see your appreciative post.

Ha! Perhaps not. Sometimes I forget while searching for info that I am not reading current threads. 😁

Not the first time won?t be the last Jay!