Turn Fin Operation

[LohringMiller]

Take a look at this video for a better idea of how a turn fin works than the single picture in my article.

Lohring Miller

PS Thanks Tyler

 

[Terry Keeley]

Great article, thanks!

Tyler's boat is hydro foiling on the fin for most of the run, wonder if he has it aligned with the "perceived" water line? The way it's running it looks like it would be angled down at the rear but maybe our fins lift more than we think?

I know this was discussed already but what's your take on the breaks in the water coming off this fin shot by Ian Inverarity?

 

[RaceMechaniX]

Terry,

My turn fin is actually angled down relative the water line. We figured the leading edge is too shallow and this is what's leading to all the lift. We will try a more vertical leading edge with the rest of the geometry unchanged.

Tyler

 

[Mike Hughes]

No matter what you do, anything that you stick into the water will hydrofoil. Its what you do with it that counts. The more you rake the turn fin the less lift will be created. The leading edge taper will create lift. The curled or bent tuck fin will create lift if it pushed forward. The opposite is true if pulled back. With a sport type boat you have more weight on the sponson to counter act this lift. You can run a more veritcal style and bite into the turns better. Which is needed because boats are typically heavier. Just a few thing learned after building 1K plus fins over the years.

Mike

 

[Terry Keeley]

Terry,

My turn fin is actually angled down relative the water line. We figured the leading edge is too shallow and this is what's leading to all the lift. We will try a more vertical leading edge with the rest of the geometry unchanged.

Tyler

You mean the TE is angled down relative to the eater line?

 

[stan simpson iv]

Does your fin have a radius,or does it have two bends(breaks) on it?? My Jae's, if the TE is down in the back it will have the same effect. The right sponson will not touch the water. A fine line in adjustment will make or break the handling of the JAE. JMO

 

[stan simpson iv]

Great article, thanks!

Tyler's boat is hydro foiling on the fin for most of the run, wonder if he has it aligned with the "perceived" water line? The way it's running it looks like it would be angled down at the rear but maybe our fins lift more than we think?

I know this was discussed already but what's your take on the breaks in the water coming off this fin shot by Ian Inverarity?

I guess the fin is flexing pretty fast causing that look.

 

[Andy Brown]

Great article, thanks!

Tyler's boat is hydro foiling on the fin for most of the run, wonder if he has it aligned with the "perceived" water line? The way it's running it looks like it would be angled down at the rear but maybe our fins lift more than we think?

I know this was discussed already but what's your take on the breaks in the water coming off this fin shot by Ian Inverarity?

I guess the fin is flexing pretty fast causing that look.

" I guess the fin is flexing pretty fast causing that look."

I think that is correct Stan. We discussed that possibility in the other thread with Ian's turn fin shots a while back.

Looks like about 20,000 to 30,000 cycles per minute.

I wonder if it matches prop blade beats? Would 2 and 3 blade props change the frequency?

Or is it the natural harmonics of the fin which is controlled by material, size, shape?

R/C boats never get boring!.....guess that is why I have been playing with them for 45 years now.

 

[Alan Elzer]

Take a look at

What kind of camera was used.. nice video
Sent from my SM-N920V using Tapatalk

 

[warlokboats]

Is there a angle of the curve that you should not go past?

 

[RaceMechaniX]

Terry,

My turn fin is actually angled down relative the water line. We figured the leading edge is too shallow and this is what's leading to all the lift. We will try a more vertical leading edge with the rest of the geometry unchanged.

Tyler

You mean the TE is angled down relative to the eater line?

Opposite. The front edge is down relative to the rear. It should be reducing lift. Should be. I did not try it neutral or trailing edge down.

This was shot with a GoPro Seesion 5 at 4K/30 FPS.

 

[RaceMechaniX]

Does your fin have a radius,or does it have two bends(breaks) on it?? My Jae's, if the TE is down in the back it will have the same effect. The right sponson will not touch the water. A fine line in adjustment will make or break the handling of the JAE. JMO

Stan it is a 2 bend design.

 

[Terry Keeley]

Terry,

My turn fin is actually angled down relative the water line. We figured the leading edge is too shallow and this is what's leading to all the lift. We will try a more vertical leading edge with the rest of the geometry unchanged.

Tyler

You mean the TE is angled down relative to the eater line?

Opposite. The front edge is down relative to the rear. It should be reducing lift. Should be. I did not try it neutral or trailing edge down.

This was shot with a GoPro Seesion 5 at 4K/30 FPS.

Figured you had it that way, crazy how much it lifted. Any chance you have a photo of the fin? How was it sharpened?

4K in a mini camera, crazy!

 

[LohringMiller]

Terry, have you tried using the Solidworks fluid flow program to study rudders and turn fins? I wonder if it can handle surface effects and ventilation.

Lohring Miller

 

[Terry Keeley]

Terry, have you tried using the Solidworks fluid flow program to study rudders and turn fins? I wonder if it can handle surface effects and ventilation.

Lohring Miller

I haven't but it might be interesting to try. Ah, so many projects, so little time.

 

[raptor347]

You need to look at the series of videos. That is essentially the heat race turn fin I built for the boat in 2014. When running at close to heat racing speeds, the fin doesn't lift nearly as much. With every prop change (increase in speed) it rides higher up on the very swept LE. Less sweep angle will reduce the lift at higher speed we see at TT's

All that said, the corner performance is fantastic through the speed range.

 

[shoboat]

Brian,

I agree the videos were great seeing what is really going on

with the propellers and turn fins. Your boat and fin design are

AWESOME. i liked the rod to the tub like the Japanese have

had for years on their boats. We learn something new everyday.

Seeing Is Believing,

Mark Sholund

 

[raptor347]

Tyler added the rod when he started pushing the speeds up.

I'm working on the next evolution of that boat biased to TT's.

 

[Alan Elzer]

Terry,

My turn fin is actually angled down relative the water line. We figured the leading edge is too shallow and this is what's leading to all the lift. We will try a more vertical leading edge with the rest of the geometry unchanged.

Tyler

You mean the TE is angled down relative to the eater line?

Opposite. The front edge is down relative to the rear. It should be reducing lift. Should be. I did not try it neutral or trailing edge down.
This was shot with a GoPro Seesion 5 at 4K/30 FPS.

Thnx
Sent from my SM-N920V using Tapatalk

 

[Michael Costanzo]

Brian,

I agree the videos were great seeing what is really going on

with the propellers and turn fins. Your boat and fin design are

AWESOME. i liked the rod to the tub like the Japanese have

had for years on their boats. We learn something new everyday.

Seeing Is Believing,

Mark Sholund

mark, have been using the rod on the fin to the tub for over 20 years.works very well,mike.