Another Rudder Question (NACA)

[John Stevens]

I'm starting to understand a bit about NACA. How do I decide which to go with? 0012?

TIA,


John Stevens

[water addict]

0012 is a great all around section. If you're still planning to do it on your Precision 18, it's a good bet.

[Ron Cook]

The 0012 is always a good way to go. When you make it do so very acurately or it will hummmmmmm! If you can take the time to make it with the aft hollow and a very fine aft edge I know you will be very happy with it. The 0012 foil is a nice all around foil. I have used it on monohulls and multihulls with good results.

Ron Cook

[Paul B]

Originally Posted by Ron Cook

The 0012 is always a good way to go. When you make it do so very acurately or it will hummmmmmm! If you can take the time to make it with the aft hollow and a very fine aft edge I know you will be very happy with it. The 0012 foil is a nice all around foil. I have used it on monohulls and multihulls with good results.

Ron Cook

Hollow in the 0012? Are you sure that's what you mean?

[John Stevens]

How do I make the aft hollow? And... on the aspect ratio- is higher better? Also, I'm planning on putting a wing on the bottom to make it shorter for shallow water. How do I figure the size of the wing?


TIA,


John Stevens

[Andy P]

The NACA 00 series has no hollows!
It has convex all the way to the trailing edge.

I would agree that this series is an excellent all purpose section, - at 10 to 12 % seems best compromise for strength, drag and resistance to stalling and ventilation.

[Paul B]

Originally Posted by Andy P

The NACA 00 series has no hollows!
It has convex all the way to the trailing edge.

Ding, ding, ding..We have a winner!

[dougfrolich]

I think what was ment above, is that the 0012 section is very often, typically modified with a hollow toward the exit, as on say a 63 series.

[Andy P]

Then it's not an 00 section is it?

The 63 series can also make good rudders for faster boats.
The 63 section variant I use also has no hollows, but is very nearly flat near the trailing edge.

It can ventilate more easily than 00x. This is rare, but if it happens, the flow reattaches very quickly if the blade is realigned with the flow for a moment.
The 00x section seems to suck air for a long time before you can steer again.

[dougfrolich]

I agree with you totally!!
All I was saying is that it is common for builders to start with the 0012 section, for what ever reason, and modify it abit to make it better. Somtimes stuffing a rudder post of a given size, down the rudder, is the reason for choosing the 0012 section--it's kinda fat were the post needs to go. But I agree with your comments.

[Ron Cook]

It has been years since I designed a rudder for a sailboat. Memories the second thing to go, don't remenber the first.....

I stand corrected the oo series has no hollow. I went back through my records, because of the humming at higher speeds we went to the 63 series with the hollow. The 0012 foil is still a very nice foil.

The performance difference between a foil well made to one that is exceptionally constructed to very close tolerances is pronounced and well worth the extra effort.

Thanks For the correction,

Ron Cook

[John Stevens]

How do I hollow out the end and what does it look like?

Also, I'm making a wing on the bottom. How should that be shaped?

TIA,

John Stevens

[Andy P]

Originally Posted by John Stevens

How do I hollow out the end and what does it look like?

Also, I'm making a wing on the bottom. How should that be shaped?

TIA,

John Stevens

If you mean how to fit a pivot stock into the blade - then you can either make in two halves, rout out the shape of the stock in the core in each side, and glue it back together.

Or starting from a rectangular blank, rout out the shape of the stock on one side so the stock fits in the middle, glue it in and fill the hole. Then proceed with the shaping.

00 series again is good. 63 perhaps not so good as this will be working at larger angles ( outside the low drag bucket ) more often than a blade used for steering - due to pitching ( and on a small boat nosedving )

[Skippy]

What 63-series section is the best comparison or replacement for 0012? I found 63-012a, but it doesn't look concave to me. Which one are you talking about?

Edit: Okay, 63(1)-012 looks like it.

[Ron Cook]

The 63012a does not have the hollow. You need the 63012. If someone would tell me how to post drawings I'll post the 63012.

The 0012 has a sightly larger stall angle then the 63012. I think the 63 is a better high speed section. The nose of the 0012 is a bit blunt for high speed.

Ron Cook