Pushing 100 RoadRunner Twin 90s VACs

[Terry Keeley]

Hey Marty:

I follow the tech paper for "high strength alloys", Octura uses 20C (C82500).

Sooo, I take the raw prop, heat to 1450F for 1/2 hr. or so then water quench. I then do all my balancing etc and "age" at 625-650F for 3 hrs. followed by a slow cool. Props keep their edge and have a nice "ring" to them after that!

Tried the ss bag but couldn't get it open or poke holes in it fast enough, was a little hard to handle to at 1450*.

Doing the raw prop first gives a nice final finish as all the scale etc is cleaned off while balancing.

Yup, you can get too thin, made a pass a few years ago and boat was making a weird "brrrrrr" sound, though I blew a coupler, brought it in and was missing a blade!

This is the only one in 20 years or so though and it was probably a little radical...

 

[Chris Wood]

if you don't heat treat and get a prop ready to go.. test it and you like it.

can you go back and heat treat it after you tested it.. and will it change any during heat treat?

chris

 

[Terry Keeley]

if you don't heat treat and get a prop ready to go.. test it and you like it.

can you go back and heat treat it after you tested it.. and will it change any during heat treat?

chris

Hey, your're fast enough without any of our help!

Seriously, you can heat and quench, re-work, bend whatever and re-harden as often as you want.

I used to carry a small toaster oven with me to record trials "just in case".

 

[Chris Wood]

lol i don't know about the FAST ENOUGH part terry,

thanks for the info though.. i have been wanting to heat treat just never have done it

chris

 

[BigChuck]

JW & Jose.................My testing will start right after the holiday. I will have the house back in order and the Garage will be mine AGAIN!!!! :lol: :lol:

Starp it to the BIKE!!!! I can't even get to it to go for a blow. FURNITURE to the Ceiling!!!! But like I said I will start testing in about two weeks.

Oh an yes, I too have a few "Special" Props!!!

 

[Buckshot]

I can see it now.......Chuck dragging knee with a twin on his back....... :lol: :lol: :lol: :lol: :lol:

 

[BigChuck]

BUCK.................YOU ARE FUNNY!!! :lol: :lol: :lol: :lol:

BUT I have been working on the Knee DRAGGING!!! And LOVING IT!!! B) B) B)

 

[shoboat]

Boaters,

I am in the propeller shop all day today and no calls yet.

I guess everyone has found their answers here on I/W.

Thanks For Reading,

Mark Sholund

231.590.3023

 

[Luca Gray]

Mark.

i thought you are way to busy working on propellers,

to talk to people, lol

cheers Luca

 

[shoboat]

Luca,

Talking to propeller customers and airline customers is my job.

I always take time for things that are important in life.

I am pretty busy in the propeller shop, but I always like to talk

to my customers.

It is the best way to learn about their set ups.

Thanks,

Mark Sholund

 

[Joe Warren]

Luca,

Talking to propeller customers and airline customers is my job.

I always take time for things that are important in life.

I am pretty busy in the propeller shop, but I always like to talk

to my customers.

It is the best way to learn about their set ups.

Thanks,

Mark Sholund

P.S. We been out running Boats...........

 

[Jeff Lutz]

Joe,

Thanks for the tip on the low thrust cone! B)

I was making a comment that another boater Had stated that we cannot go any faster than Leading Edge Pitch X RPM....... I go faster with T.E. cup.

Are you saying here you go faster than the leading edge pitch by cupping the T.E? How much faster? How did you work out you were going faster than the leading edge pitch? I must admit that in testing with a rpm logger and a Stalker radar I havent been able to do this with props I have been cupping.

Ian.

Ian:

I agree with you on that....

Joe said he gets rid of the tongue (leading edge pitch) as much as he can and that changes the effective leading edge pitch. That is correct. If you want to see this REALLY in play, run an X Series Prop and measure the speed. The remove some leading tongue and check again. You will see that the speed is way up. Remove more and the speed goes up more. REASON: on an X Series Prop they are essentially a prop that has increasing pitch from the first part in the water to the trailing edge. When the water shoots off the trailing edge the next thing in the water is the super low pitch part of the other blade. That acts like a governor and removing that area removes that effect to a large degree.

Joe says that he removes the leading part of the blade on a 1400 or 1600 series prop to do the same thing. Those props are called true pitch props because the pitch is the same across the entire prop. BUT, after adding pitch and cup to the rearward part of the blade it is no longer a true pitch prop. It is more like the X Series Prop and will benefit from removal of the tongue part of the prop.

I would suggest that it makes sense to use the definitions that the prop guys are using so that we all talk the same language. Right or wrong....

Hope this helps.....

This is Exactly Correct.... & V cutting your T.E. Hydro & Mono props out of the center of the hub makes the prop think it has more Rake another feature we would like to see in some newier designed props. I see Marty`s props have material removed all the way across the Trailing Edge. This effectively makes Rake too.... Has anyone seen the Sholund VX 467 props? It has all of these features. That paticular VX467 prop will rum more RPM & speed than ever before...... Only thing faster is a VX470!! :blink: :huh: B) I have recently received some 1662 5.5 5.7 cup from Mark that have a tiny barr cut.... Plus the center of the slight barr cut has a slight V cut. or a (swirl turbo) cut... I found the V cut helps the boat launch bigger props & turn great Rpm. But dont kill Lift as much & drop the back of the boat like a a Barr cut.. This is just my experience....... B)

Joe, No matter how you cut and shape your prop your not changing the rake AT ALL.

 

[Ian Inverarity]

I was thinking the same thing Jeff.

http://www.rundquist.com/how_rakes.htm

Ian.

 

[Joe Warren]

You think jeff?

 

[shoboat]

Boaters,

For those of you that don't know, the RAKE ANGLE is determined by how

the blades are attached to the hub. And the CUP is the angle of the blade

face at the trailing edge before the water exits the trailing edge. The best way

to think of cup, is it is like a ski jump at the end of the hill before the skiers

launch off into the air. It is measured in degrees and converted to inches.

The only way to change rake angle is to cut off the blades and remount them

at a different angle. If you cut the trailing edge of a propeller it just changes

the way the water comes off the trailing edge, that is all. Rake changes are

done when the propeller is designed from the start. We could use more rake

in our propellers, I think 17 degrees will be about the optimum rake angle.

Thanks For Reading,

Mark Sholund

 

[Joe Warren]

Jeff, When you cup the tip`s of the prop you have changed the RAKE! You can add Progressive / Rake without bending the entire Blade on the prop !! I tweak my props for heat racing. I`am not a S A W Dude....... I normally bend on a spec heat racing props with the attempt to Turn as much RPM as Possible & Push the boat forward harder.... As you know you must have the Engine, Pipe, & Boat performing @ its max. Before you begin to tweak out the prop. Some know when they have reached the Limits of the boat. Todays modern engine have more Power & will turn BIG RPM with some Big cupped props. Now its time to figure out the combo`s Best Engine, Best pipe, Best pipe length, Then onto the Prop. Its a New Game in F Hydro Heat racing classes. I dont know if we can run 100 mph heat trim? But we can **** sure heat race in the mid 90`s. A 15lb Twin running 90 mph will get you attention. Now add another 7-8 boats out there @ the same time.

 

[Jeff Lutz]

Jeff, When you cup the tip`s of the prop you have changed the RAKE! You can add Progressive / Rake without bending the entire Blade on the prop !! I tweak my props for heat racing. I`am not a S A W Dude....... I normally bend on a spec heat racing props with the attempt to Turn as much RPM as Possible & Push the boat forward harder.... As you know you must have the Engine, Pipe, & Boat performing @ its max. Before you begin to tweak out the prop. Some know when they have reached the Limits of the boat. Todays modern engine have more Power & will turn BIG RPM with some Big cupped props. Now its time to figure out the combo`s Best Engine, Best pipe, Best pipe length, Then onto the Prop. Its a New Game in F Hydro Heat racing classes. I dont know if we can run 100 mph heat trim? But we can **** sure heat race in the mid 90`s. A 15lb Twin running 90 mph will get you attention. Now add another 7-8 boats out there @ the same time.

Joe, Progressive rake in the real world, is known as " Parabolic Rake". As Mark just mentioned above,true rake is designed from the beginning, and would have to be done at the hub. Just bending the tip would not fall into the "Parabolic Rake" category to me, or lets say mercury racing.Thats all I wanted to point out. See ya, Jeff

 

[John Finch]

Jeff, When you cup the tip`s of the prop you have changed the RAKE! You can add Progressive / Rake without bending the entire Blade on the prop !! I tweak my props for heat racing. I`am not a S A W Dude....... I normally bend on a spec heat racing props with the attempt to Turn as much RPM as Possible & Push the boat forward harder.... As you know you must have the Engine, Pipe, & Boat performing @ its max. Before you begin to tweak out the prop. Some know when they have reached the Limits of the boat. Todays modern engine have more Power & will turn BIG RPM with some Big cupped props. Now its time to figure out the combo`s Best Engine, Best pipe, Best pipe length, Then onto the Prop. Its a New Game in F Hydro Heat racing classes. I dont know if we can run 100 mph heat trim? But we can **** sure heat race in the mid 90`s. A 15lb Twin running 90 mph will get you attention. Now add another 7-8 boats out there @ the same time.

Joe, Progressive rake in the real world, is known as " Parabolic Rake". As Mark just mentioned above,true rake is designed from the beginning, and would have to be done at the hub. Just bending the tip would not fall into the "Parabolic Rake" category to me, or lets say mercury racing.Thats all I wanted to point out. See ya, Jeff

A lot of boaters refere to adding rake by only changing the trailing edge angle. Back when we made our props on the hughey dial a prop we would tilt the whole blade backwards to add rake when we soldered the blade to the hub. I think this is what Jeff is refering to as opposed to just cutting the trailing edge from tip to hub with more material taken off as you go closer to the hub. I did experiment with the x series props and took off the leading edges as well as stretched them out with less bend and gained about 2 mph as I remember it on my mono hulls many years back. I did it on my h22 props when I did record trial SAW events on my 60 size mono too. You only go a little bit or you start slapping the water. I look at it like gearing a car. The x-series props accellerate quick like a low gear in a car, but they peter out at top end.

 

[Joe Warren]

Jeff, When you cup the tip`s of the prop you have changed the RAKE! You can add Progressive / Rake without bending the entire Blade on the prop !! I tweak my props for heat racing. I`am not a S A W Dude....... I normally bend on a spec heat racing props with the attempt to Turn as much RPM as Possible & Push the boat forward harder.... As you know you must have the Engine, Pipe, & Boat performing @ its max. Before you begin to tweak out the prop. Some know when they have reached the Limits of the boat. Todays modern engine have more Power & will turn BIG RPM with some Big cupped props. Now its time to figure out the combo`s Best Engine, Best pipe, Best pipe length, Then onto the Prop. Its a New Game in F Hydro Heat racing classes. I dont know if we can run 100 mph heat trim? But we can **** sure heat race in the mid 90`s. A 15lb Twin running 90 mph will get you attention. Now add another 7-8 boats out there @ the same time.

Joe, Progressive rake in the real world, is known as " Parabolic Rake". As Mark just mentioned above,true rake is designed from the beginning, and would have to be done at the hub. Just bending the tip would not fall into the "Parabolic Rake" category to me, or lets say mercury racing.Thats all I wanted to point out. See ya, Jeff

Well, I would like to see some new props with More (True Rake) & More COB Pitch . Before...... they were not needed... But, Todays Engines will allow it Without a Great loss of RPM. Untill then, We will contuine to bend the $#!^ out what we have.......

 

[BobFerguson]

Jeff, When you cup the tip`s of the prop you have changed the RAKE! You can add Progressive / Rake without bending the entire Blade on the prop !! I tweak my props for heat racing. I`am not a S A W Dude....... I normally bend on a spec heat racing props with the attempt to Turn as much RPM as Possible & Push the boat forward harder.... As you know you must have the Engine, Pipe, & Boat performing @ its max. Before you begin to tweak out the prop. Some know when they have reached the Limits of the boat. Todays modern engine have more Power & will turn BIG RPM with some Big cupped props. Now its time to figure out the combo`s Best Engine, Best pipe, Best pipe length, Then onto the Prop. Its a New Game in F Hydro Heat racing classes. I dont know if we can run 100 mph heat trim? But we can **** sure heat race in the mid 90`s. A 15lb Twin running 90 mph will get you attention. Now add another 7-8 boats out there @ the same time.

Joe, Progressive rake in the real world, is known as " Parabolic Rake". As Mark just mentioned above,true rake is designed from the beginning, and would have to be done at the hub. Just bending the tip would not fall into the "Parabolic Rake" category to me, or lets say mercury racing.Thats all I wanted to point out. See ya, Jeff

Well, I would like to see some new props with More (True Rake) & More COB Pitch . Before...... they were not needed... But, Todays Engines will allow it Without a Great loss of RPM. Untill then, We will contuine to bend the $#!^ out what we have.......

Here is My thoughts light weight x great = JAGUAR 3 and all else is drowned out by the jags water spray..................Dang im going to here it Now...............................................