Speedmaster 20 mono, good day testing

[Ian Inverarity]

Terry,

As I understand it the LE pitch is pretty much as fast as you can go for a certain RPM, but unless the pitch progression and blade area is well matched to the load of the boat at speed then the speed will be less than the LE pitch. Maybe you need more cup? Andy Brown recently suggested the limiting pitch is actually the LE pitch on the back face of the prop, which will be less than on the face of the prop, and this makes sense to me. Another good reason for thin and sharp LE!

 

[El Zorro]

Dick, Are you taking the on coming 58 mph doppler into account?

Even so, depending on how the X437/3 is worked/finished, 39K is very probable.

I've seen the MAC 21 buggy engine turn 45,000 many times and live.

On-road .21's turn 39,000 to 45,000 routinely.

No need to worry with any doppler effect on RPM readings when we are at the lake testing. If you know what prop did what speed at what RPM and how the boat handled in the water you have 99% of the important information that you need. You take enough notes on engine/pipe/prop/RPM/boat, etc., etc. set-ups and eventually you start to see patterns on what works and what doesn't. I was doing Picco.21's for a friend that raced 1/8 scale pavement cars in the early to mid 1990's that would top 65 MPH at the end of the longest straightaway at 40,000 plus RPM. Won his share of races, too. Did a lot of work to help them get there, but you had to make sure the bottom end of the rod was always going to get enough oil! Seems a little silly to argue over what the engine was turning......................I know what my audio tach said. That little sucker was screaming!

Dick Tyndall

 

[Terry Keeley]

Terry:

Nice post with a lot of "MEAT".

My point in my post initially was just to say that to make a blanket statement about what was going on with Phil's boat was impossible without some measurement device like the Eagle Tree System, etc. EACH BOAT will be different in it's slip percentage, depending on a host of variables.

Kind of like trying to define the pipe temp to design the perfect pipe. IMPOSSIBLE with so many variables to state that we run at a specific EGT. Loads, boat efficiency, etc, etc.

This is what makes this hobby so much fun. MANY things to think about and study. When you start to think that you know something, you find something else that leads you in a different direction.

Makes it humerous when someone says it is so, just because......

I tend to take note when AB says something. Look at the results, they speak for themselves. We have been getting a LOT of information lately from him - keep it coming, it is helping me, and others I am sure, understand some things that we have never researched. Gives me much more to look into....

When I finally graduated from the Hughey Pitch Gauge to the Woods model, it upped my game. I believe that the Eagle Tree stuff will do the same. I plan to start using it right away to answer some questions that I have had for years.

When I saw what the Eagle Tree was doing for a buddy I knew it would be a great tool for my SAW program. At first I thought the rpm readings were off but I tend to believe them now after reading "testimonials" on their forum and some testing with an old optical tach.

I've compared data with Mike Rappold on here, he's been using the system for years now and is logging all kinds of stuff like EGT, head temp etc, maybe he'll chime in.

The Wood's gauge is a nice unit, I like Franco's ART gauge. Used a Hughey gauge too for years.

 

[Terry Keeley]

Terry,

As I understand it the LE pitch is pretty as fast as you can go for a certain RPM, but unless the prop progression and blade area is well matched to the load of the boat at speed then the speed will be less than the LE pitch. Maybe you need more cup? Andy Brown recently suggested the limiting pitch is actually the LE pitch on the back face of the prop, which will be less than on the face of the prop, and this makes sense to me. Another good reason for thin and sharp LE!

I'm reworking the props as we speak! Also looking at ways to get more blade in the water...

 

[Andy Brown]

Terry,

As I understand it the LE pitch is pretty as fast as you can go for a certain RPM, but unless the prop progression and blade area is well matched to the load of the boat at speed then the speed will be less than the LE pitch. Maybe you need more cup? Andy Brown recently suggested the limiting pitch is actually the LE pitch on the back face of the prop, which will be less than on the face of the prop, and this makes sense to me. Another good reason for thin and sharp LE!

I'm reworking the props as we speak! Also looking at ways to get more blade in the water...

Yes Terry, what nitrocrazed said. While you're at it, turn that prop over and measure the face of the L.E. Try to measure just the first 5 degrees. You may be surprised just how low the pitch is. Also, the more narrow a blade is the more difficult it is to keep the front and back pitch close together. We are looking for the smallest possible wedge, but we need a certain blade thickness to maintain the prop structure, so as you can see, a narrow blade will by default create a steep wedge and therefore a large front/back pitch difference.

This is a "biggie" on pointed props like V900's. Near the tip the wedge becomes very steep.

 

[Andy Brown]

Terry,

Is your RPM and GPS synced with a 1 second separation or is the boat speed actually taking that long to catch up to the rpm? If the latter is true, then the graphs definitely mirror the huge prop slippage.

I do suspect the latter is true, because the quick gains in RPM are followed by a long delay in speed increase, while on the other hand the slow rpm increases are followed by a much sooner speed response.

Note the improvement from the first graph to the last. The slower over all rpm increase netted out the highest speed with less peak rpm. (last graph)

 

[Ian Inverarity]

I always thought you would go as fast as the LE pitch if you had a low drag, clean running hull and that progression only robs HP and doesn't make you go any faster. Now I'm not so sure. :unsure:

Terry,

Picking up on this point, as I understand it, pitch progression accelerates water away from the prop, creating thrust. This of course also absorbs HP. If the prop is running at less than the LE pitch it can be pitched more to increase the thrust to match the load of the boat, assuming the engine can stand the extra load. Once the LE pitch speed is reached then adding additional pitch will then rob HP while not making the boat faster.

Ian.

 

[aaron alberico]

I always thought you would go as fast as the LE pitch if you had a low drag, clean running hull and that progression only robs HP and doesn't make you go any faster. Now I'm not so sure. :unsure:

Terry,

Picking up on this point, as I understand it, pitch progression accelerates water away from the prop, creating thrust. This of course also absorbs HP. If the prop is running at less than the LE pitch it can be pitched more to increase the thrust to match the load of the boat, assuming the engine can stand the extra load. Once the LE pitch speed is reached then adding additional pitch will then rob HP while not making the boat faster.

Ian.

Ian

buddy, so very true, as we have tested, as you reach the potential of the LE/pitch the only way to go faster is turn more rpm's

or time to step in propeller LE/pitch

regards Aaron

P.S Terry very nice rpm's from 67's motor

 

[Terry Keeley]

Terry,

Is your RPM and GPS synced with a 1 second separation or is the boat speed actually taking that long to catch up to the rpm? If the latter is true, then the graphs definitely mirror the huge prop slippage.

I do suspect the latter is true, because the quick gains in RPM are followed by a long delay in speed increase, while on the other hand the slow rpm increases are followed by a much sooner speed response.

Note the improvement from the first graph to the last. The slower over all rpm increase netted out the highest speed with less peak rpm. (last graph)

Was wondering about that and figured it was a delay somehow in the GPS, looking at it closer now I think you're probably right.

Will be interesting to see if the graphs tighten up as the efficiency increases, which is my #1 my goal as the motor doesn't seem to want to turn any faster (at least in it's present form!)

For my homework I'll have a closer look at the back side of the blade, check the first 5* and report back tomorrow.

 

[Terry Keeley]

I always thought you would go as fast as the LE pitch if you had a low drag, clean running hull and that progression only robs HP and doesn't make you go any faster. Now I'm not so sure. :unsure:

Terry,

Picking up on this point, as I understand it, pitch progression accelerates water away from the prop, creating thrust. This of course also absorbs HP. If the prop is running at less than the LE pitch it can be pitched more to increase the thrust to match the load of the boat, assuming the engine can stand the extra load. Once the LE pitch speed is reached then adding additional pitch will then rob HP while not making the boat faster.

Ian.

This is what I'm discovering but I had no idea the slip would be so huge (according to my "standard"). :lol:

 

[Terry Keeley]

P.S Terry very nice rpm's from 67's motor

Thanks, it doesn't seem to wanna turn any higher tho. Got it to come on to a 1/2" shorter pipe when the air was better and it didn't turn any faster. :blink:

 

[Ian Inverarity]

Ever measure an Octura 2260? The Octura chart claims 5.192". However, the COB 6.2" and the trailing edge of that prop is 8.65".

Andy,

How do you measure COB? What is the significance of COB in relation to the discussions of pitch progression and so on?

Ian.

 

[Andy Brown]

Ever measure an Octura 2260? The Octura chart claims 5.192". However, the COB 6.2" and the trailing edge of that prop is 8.65".

Andy,

How do you measure COB? What is the significance of COB in relation to the discussions of pitch progression and so on?

Ian.

Ian,

On this 2260, I just measured the center 20% of the blade and took the sweep at about 60% out. The LE on that same prop was only 4.1" That averaged with the TE gives and average total pitch of 6.3" Way above the Octura pitch claim. What a crazy prop! Over 100% progression!

Oh and to further answer your question some props hold the LE pitch across most of the blade and then only have a TE pitch increase. I prefer the gradual progression increase from LE to TE. All of my CNC props are that way as was this 2260 in question. This helps maintain water/blade contact across the full blade from LE to TE.

I think in Terry's case he is loosing contact and the last half of the prop is only seeing air!...maybe even the last 70%.

When I cup a 1400 prop, which is nearly constant pitch, I reach into the blade to the center and start adding progression there, not just the last 20% or so.

Terry, The 2260 could be an interesting prop for you to try. 4.1" @ 28K is 108 mph. Grab one a try it. If it's too much load just keep back cutting until it goes 108. Actually it shouldn't run that fast because of the front side pitch we talked about, but it should get close. You could cut the last half of the blade off and still have 6.0" on the TE.

If that works, grab another 2260 and cut the LE back until you get a LE pitch of 4.5" to 4.7"and also back cut the TE to get it in that 6.0" to 6.5" range. Should get you over 115 mph.

Also, on that 1/2" shorter pipe experiment. "The air was better". Meaning colder I assume? Pumping colder air through the engine cools and slows the combustion. This leads to lower EGT, which in turn leads to slower wave speed in the pipe. So in reality the 1/2 shorter pipe just got you back to "square one".

 

[shoboat]

Terry,

I have two Octura 2260's here new in the bag that I will give to you.

I just need your shipping address please?

Have Fun Testing,

Mark Sholund

 

[Marty Davis]

Ever measure an Octura 2260? The Octura chart claims 5.192". However, the COB 6.2" and the trailing edge of that prop is 8.65".

Andy,

How do you measure COB? What is the significance of COB in relation to the discussions of pitch progression and so on?

Ian.

Ian,

On this 2260, I just measured the center 20% of the blade and took the sweep at about 60% out. The LE on that same prop was only 4.1" That averaged with the TE gives and average total pitch of 6.3" Way above the Octura pitch claim. What a crazy prop! Over 100% progression!

Oh and to further answer your question some props hold the LE pitch across most of the blade and then only have a TE pitch increase. I prefer the gradual progression increase from LE to TE. All of my CNC props are that way as was this 2260 in question. This helps maintain water/blade contact across the full blade from LE to TE.

I think in Terry's case he is loosing contact and the last half of the prop is only seeing air!...maybe even the last 70%.

When I cup a 1400 prop, which is nearly constant pitch, I reach into the blade to the center and start adding progression there, not just the last 20% or so.

Terry, The 2260 could be an interesting prop for you to try. 4.1" @ 28K is 108 mph. Grab one a try it. If it's too much load just keep back cutting until it goes 108. Actually it shouldn't run that fast because of the front side pitch we talked about, but it should get close. You could cut the last half of the blade off and still have 6.0" on the TE.

If that works, grab another 2260 and cut the LE back until you get a LE pitch of 4.5" to 4.7"and also back cut the TE to get it in that 6.0" to 6.5" range. Should get you over 115 mph.

Also, on that 1/2" shorter pipe experiment. "The air was better". Meaning colder I assume? Pumping colder air through the engine cools and slows the combustion. This leads to lower EGT, which in turn leads to slower wave speed in the pipe. So in reality the 1/2 shorter pipe just got you back to "square one".

Andy:

I sure agree with you on the adding of pitch throughout at least 50-60% of the blade depth to make the increase in pitch as gradual as possible. I agree that if you put the pitch increase mostly in the back of the blade it will fill the start of the bend with air. Gradual seems to increase prop efficiency and also deliver the water to the tips with the least amount of air.

Have you ever played with a small press that also has a pressure gauge to press a gradual bend into a prop using a similar pressure on both blades? OR, just the pliers and ball?

 

[Terry Keeley]

Terry, The 2260 could be an interesting prop for you to try. 4.1" @ 28K is 108 mph. Grab one a try it. If it's too much load just keep back cutting until it goes 108. Actually it shouldn't run that fast because of the front side pitch we talked about, but it should get close. You could cut the last half of the blade off and still have 6.0" on the TE.

If that works, grab another 2260 and cut the LE back until you get a LE pitch of 4.5" to 4.7"and also back cut the TE to get it in that 6.0" to 6.5" range. Should get you over 115 mph.

Also, on that 1/2" shorter pipe experiment. "The air was better". Meaning colder I assume? Pumping colder air through the engine cools and slows the combustion. This leads to lower EGT, which in turn leads to slower wave speed in the pipe. So in reality the 1/2 shorter pipe just got you back to "square one".

I'm working on a 2260 as we speak, gonna try it bone stock to start and was thinking of cutting back the LE and TE as you mentioned. Dunno if 100% progression is gonna go faster though... :huh:

Yup, colder and the pressure was higher, 200' PA + 0*C gave about 104%. Never thought about the cold air slowing the wave speed though, would be kinda like injecting water into the pipe, right? I had seen an 800 rpm increase per 1/4" shortening of the pipe and expected that 1/2" to push me over 30K, makes sense why it didn't happen.

At 32F I have to cut the water almost off to get any heat whatsoever in the motor, that's where my 0.010" restrictor comes in.

 

[Terry Keeley]

Terry,

I have two Octura 2260's here new in the bag that I will give to you.

I just need your shipping address please?

Have Fun Testing,

Mark Sholund

Very generous offer Mark but I have one I'm working on now, thanks!

Gonna try something you gave me a couple years ago, so much to test, so little time on the pond...

 

[Terry Keeley]

Got my homework done, the first 5* of the LE of the 2170 I am running is about 5.04" at 75%. Turned the blade over and got a big surprize! The first 10* is 3.89" and 5* is only about 3.60".

Using 3.6" the slip reduces to next to nothing, but I'm not sure I understand how the back side of the blade comes into play when the face is doing the work. :blink:

Here's a pic of Franco's gauge and the 2170 I'm working on:

 

[Andy Brown]

Terry,

If you go just ONE MPH faster than 3.6" X 28,000/1057 you are PUSHING the 3.6" blade face into the water in front of the prop.

3.6" X 28,000/1057 = 95.4 MPH, therefore you are PUSHING that blade surface into the water at 8 mph when you ran 103+ mph. Can you say Plowing water?!?!

3.89" X 28,000/1057 = 103 mph. So there you have it. The first 5* of the LE is Plowing water and the next 5* will plow more water if you exceed 103 mph. That takes Horsepower!

In reality you have already reached that prop's Limit like Aaron said. Take your time with a file and work that prop by hand to increase that pitch.

Looking forward to seeing how much pitch you can get on it and if the boat speed increases accordingly.

 

[Ian Inverarity]

Got my homework done, the first 5* of the LE of the 2170 I am running is about 5.04" at 75%. Turned the blade over and got a big surprize! The first 10* is 3.89" and 5* is only about 3.60".

Using 3.6" the slip reduces to next to nothing, but I'm not sure I understand how the back side of the blade comes into play when the face is doing the work. :blink:

Here's a pic of Franco's gauge and the 2170 I'm working on:

Terry,

Nice tip on the gauge, did you make that?

The back side of the prop of course moves thru the water at the same speed as the working face, so if the boat was going faster than the back face LE pitch then the back face LE would actually impede water flow on the back face.

Ian