Super thin titanium rudder blades.

[Terry Keeley]

lol! You guys are funny.

I remember when "Uncle" Bill Mcgraw used to bring all his messed up Speedmaster rudders to Toledo each year and sell them cheap. Guys would snap them up and fill holes etc. with JB weld. Now I know his pain!

Yup Dave, it's the overall "profile" I'm trying to reduce. It's not only drag that's the problem, it's also lift which is super important to reduce on the SAW boat. Also thought about a tube welded/glued to the back.. My toolmaker buddy suggested other ways to make the hole that involved farming it out, in the end they were all too expensive so I figured I'd bring it in house.

Good thing I'm not trying to make a living from them.

 

[dave roach]

Terry

The long drill that you are using will bow in the middle when pressure is used and cause it to start to drill off center.I would start with a short drill and start going up in lenght .

 

[Terry Keeley]

Terry

The long drill that you are using will bow in the middle when pressure is used and cause it to start to drill off center.I would start with a short drill and start going up in lenght .

Thanks, yup.

Was starting with a stub, then taper and finally the last 2" with the long one.

Just had a good look at my fixture and the drill bushing was off center about 0.004! Got it down to a few tenths now and going with a solid carbide stub drill to start. Hope the effort pays off...

 

[longballlumber]

cool stuff! thanks for sharing.

 

[shoboat]

Terry,

"It's not only drag that's the problem, it's also lift which is super important to reduce on the SAW boat".

Like Glenn just did with his 12-SAW Hydro the higher rake angle will kill the lift even with a 2.3 pitch ratio.

19 to 29 degrees will do the job.

We are working on a carbon rudder design for one our new 12-SAW boats. Hope to see you in Flint this

year for some fast passes on some smooth water.

Thanks For The Videos,

Mark Sholund

 

[Jack ODonnell]

Just don't drink the water !

 

[dwilfong]

How much water do you real need?????

Putting a very small tube down the back will make for a very thin blade.

No need for the extra thickness for a hole to be drilled.

The wedge angle can be very low with this in mind.

 

[Terry Keeley]

Terry,

"It's not only drag that's the problem, it's also lift which is super important to reduce on the SAW boat".

Like Glenn just did with his 12-SAW Hydro the higher rake angle will kill the lift even with a 2.3 pitch ratio.

19 to 29 degrees will do the job.

We are working on a carbon rudder design for one our new 12-SAW boats. Hope to see you in Flint this

year for some fast passes on some smooth water.

Thanks For The Videos,

Mark Sholund

Those "game changers" sure are sumpin'!

Just don't drink the water !

No kidding!

How much water do you real need?????

Putting a very small tube down the back will make for a very thin blade.

No need for the extra thickness for a hole to be drilled.

The wedge angle can be very low with this in mind.

Not much, I've been saying that for years. Why I'm gonna try a 3/64" hole next, did that in 7075 for my little 20 mono, rudder is only .100" thick!

 

[Terry Keeley]

After a bunch of testing I got a process down that ended up drilling the hole straight to a couple thou!

Testing is over!!!

 

[Ronald Van Wagnen]

Pretty thick test sample. Watch the sidewalls as you drill your real pieces. The support will be almost nill and the drill will wander and bow with no sidewall support.

I always like looking at your stuff Terry.

Keep up the good work mate.

 

[lohring]

We did some rudder testing for SAW a long time ago. I was surprised at how much some small rudder changes made in the speed. Going from a conventional aluminum rudder to a hardened knife blade was worth 6 mph around 100 mph. Cutting 1/8" off that rudder added 2 mph at 108 mph. We stopped worrying about cooling for the short SAW runs. The water pick up extended a short distance down the transom and was out of the water at speed. The boat spent a lot of time with the pick up submerged while turning after the pass so overheating wasn't a problem.

The first picture below is the first steel rudder from 2004. That boat went 105 mph. Note that the water pick up extended a little below the skeg at that time. Later pick ups were shorter and later rudders had even less area. See the second picture. Water is 800 times as dense as air so the drag of any object in the water is 800 times as much as in air.

Lohring Miller

 

[Terry Keeley]

Pretty thick test sample. Watch the sidewalls as you drill your real pieces. The support will be almost nill and the drill will wander and bow with no sidewall support.

I always like looking at your stuff Terry.

Keep up the good work mate.

Thanks brother Ron! This sample is the same as the rudders I'll be doing (1/4"), drilling the hole is the first operation...

 

[Terry Keeley]

We did some rudder testing for SAW a long time ago. I was surprised at how much some small rudder changes made in the speed. Going from a conventional aluminum rudder to a hardened knife blade was worth 6 mph around 100 mph. Cutting 1/8" off that rudder added 2 mph at 108 mph. We stopped worrying about cooling for the short SAW runs. The water pick up extended a short distance down the transom and was out of the water at speed. The boat spent a lot of time with the pick up submerged while turning after the pass so overheating wasn't a problem.

The first picture below is the first steel rudder from 2004. That boat went 105 mph. Note that the water pick up extended a little below the skeg at that time. Later pick ups were shorter and later rudders had even less area. See the second picture. Water is 800 times as dense as air so the drag of any object in the water is 800 times as much as in air.

Lohring Miller

P1010021.JPG

P1010014.JPG

You certainly know why I'm going to all this effort.

 

[lohring]

I think EDM would be the only way to make a hole in a .060" thick steel rudder blade. The hole wouldn't be big enough for significant cooling flow. If you need continuous cooling, I would look at other pick ups. We found that on heat racing gas monos a thin rudder with a prop blast pick up was faster than a stock aluminum rudder with the drilled pick up.

Lohring Miller

 

[RaceMechaniX]

I can see Terry fabricating an EDM machine in his shop just for drilling rudder rudder blades. The same ball screw drive as his lathe w/NC control, a coolant pump and a DC power supply.

What do you say Terry..........

 

[Terry Keeley]

Lol! You guys are too much.

My good toolmaker buddy tried to convince me to do these a couple of other ways, one was wire EDM from the back then having the slot/bottom welded shut. Or go in from both ends and plug the bottom somehow. Sinker EDM would take way too long ($$$) and getting a straight hole wasn't guaranteed.

I'm lucky, I have the time, and I am persistent (stubborn?).

 

[RaceMechaniX]

Sinker EDM would be the best solution. They drill very straight holes and you just let it run overnight.

Of course we could just go straight to laser drilling!

 

[lohring]

If you get tired of fooling with rudders there's always other applications for EDM. The late Wayne Trivin had fun machining tiny transfers with it.

Lohring Miller

 

[BobHorowitz]

Guys,

Just wanted to stick my two cents in. You can now get carbide drills down to about 3/64" with coolant holes going the whole length of the drill. Using them you get the coolant down to the tip of the drill. Very effective. I'll find a link and post it. They're a little spendy , but well worth it.

Bob

 

[Terry Keeley]

Guys,

Just wanted to stick my two cents in. You can now get carbide drills down to about 3/64" with coolant holes going the whole length of the drill. Using them you get the coolant down to the tip of the drill. Very effective. I'll find a link and post it. They're a little spendy , but well worth it.

Bob

That I'd like to see!

When I was sourcing drills the best I could come up with was cobalt, could find anything in carbide longer that about 1 1/2" long for the 1/16" size. Thought I'd havta go to gun drilling, there's some nice setups for lathes: