20 hydro props

[hugh hargett]

Andy,

I am saying that most propeller designs that we use for our Hydros

run on the last 30% of the tip of the blade.

There is no outer 70% of the radius.

Greg,

The middle picture looks pretty close to the last 30% in the water.

Thanks,

Mark Sholund

"The middle picture looks pretty close to the last 30% in the water."

:lol: :lol:

What about the 1st pic where the blade is running full depth?? I guess the boat is runnig at a bad attitude there Huh?

Take enough photos of a bouncing boat and you can find just the prop depth you want.

you both have great eyes obviously but tell me how does one start to set it up this (.7) or not (.7) on the table top? lol

I can tell you this if i have to come home to look at photos to set up my boat then go back out to the lake I can see now this will take forever.

Andy and Mark when you guys talk props everyone is a sponge waiting, the only problem is some of the sarcasm may get sucked up too. Most are lost with this .7 radi stuff. Ive been lost since I asked David what he meant by it on the cg thread. I see Im not the only one confused. If you two get into a tech battle here about props it will be over most of our heads and we will be even more lost. Please keep this in mind GURUS.

My eyes and ears are wide open

I just want to learn from two top people in the game

Hugh

 

[aaron alberico]

Are we talking LE pitch?

Ian,

As you know that is your limit x your rpm's

So you better of turning a Full blade 50mm 1450 or cut down 45mm 1650 at the same r's?

 

[aaron alberico]

Fastest 21 riggers I have ever seen run small dia!!!!!!!!!

 

[Mike Larson]

Inherently, thats an X vs Y question, because you could actually have the same performance exactly with both.... sure would take alot of narrowing it down to find the pair though.... ie: at what point does a cupped up 1445 meet up with a reduced bag '50 nominally of course, just to gain a little factory pitch to restart with.... yeah I'm searchin for it.... motor/pipe/setup is particular to each boat.... right along with the prop.... and... my best speeds were attained with the small diameter big pitch camp in the past.... write: 46mm 4.0, 4.2...... and, i puked at races, and testing.... ALOT. With the ski style hulls available, ease of pulling more anything has shown to be true... pipe, to boat, to prop.... whittle whittle file grind.... thanks for sharing as the learning is where its at... Mike

 

[Andy Brown]

Andy,

I am saying that most propeller designs that we use for our Hydros

run on the last 30% of the tip of the blade.

There is no outer 70% of the radius.

Greg,

The middle picture looks pretty close to the last 30% in the water.

Thanks,

Mark Sholund

"The middle picture looks pretty close to the last 30% in the water."

:lol: :lol:

What about the 1st pic where the blade is running full depth?? I guess the boat is runnig at a bad attitude there Huh?

Take enough photos of a bouncing boat and you can find just the prop depth you want.

you both have great eyes obviously but tell me how does one start to set it up this (.7) or not (.7) on the table top? lol

I can tell you this if i have to come home to look at photos to set up my boat then go back out to the lake I can see now this will take forever.

Andy and Mark when you guys talk props everyone is a sponge waiting, the only problem is some of the sarcasm may get sucked up too. Most are lost with this .7 radi stuff. Ive been lost since I asked David what he meant by it on the cg thread. I see Im not the only one confused. If you two get into a tech battle here about props it will be over most of our heads and we will be even more lost. Please keep this in mind GURUS.

My eyes and ears are wide openView attachment 36012

I just want to learn from two top people in the game

Hugh

My BEST advice to everyone. Forget the "prop gurus"! Go to the pond and adjust YOUR strut, until YOUR porp, runs great, on YOUR boat! B)

Then YOU will also be a PROP GURU when it comes to YOUR props on YOUR boat!

 

[RodneyPierce]

I do have another question to toss into this .7 radii stuff. How should people accomplish that on a JAE, with a non adjustable strut?

 

[dwilfong]

I do have another question to toss into this .7 radii stuff. How should people accomplish that on a JAE, with a non adjustable strut?

That is why that boat was built that way to take out the variables. Start messing with the strut and you will go on a long trip down tuner lane.

For most including my self that is a long and winding road.

 

[Ian Inverarity]

I do have another question to toss into this .7 radii stuff. How should people accomplish that on a JAE, with a non adjustable strut?

Umm, make it adjustable? :lol:

Sorry Rodney. h34r:

 

[hugh hargett]

Andy,

I am saying that most propeller designs that we use for our Hydros

run on the last 30% of the tip of the blade.

There is no outer 70% of the radius.

Greg,

The middle picture looks pretty close to the last 30% in the water.

Thanks,

Mark Sholund

"The middle picture looks pretty close to the last 30% in the water."

:lol: :lol:

What about the 1st pic where the blade is running full depth?? I guess the boat is runnig at a bad attitude there Huh?

Take enough photos of a bouncing boat and you can find just the prop depth you want.

you both have great eyes obviously but tell me how does one start to set it up this (.7) or not (.7) on the table top? lol

I can tell you this if i have to come home to look at photos to set up my boat then go back out to the lake I can see now this will take forever.

Andy and Mark when you guys talk props everyone is a sponge waiting, the only problem is some of the sarcasm may get sucked up too. Most are lost with this .7 radi stuff. Ive been lost since I asked David what he meant by it on the cg thread. I see Im not the only one confused. If you two get into a tech battle here about props it will be over most of our heads and we will be even more lost. Please keep this in mind GURUS.

My eyes and ears are wide openView attachment 36012

I just want to learn from two top people in the game

Hugh

My BEST advice to everyone. Forget the "prop gurus"! Go to the pond and adjust YOUR strut, until YOUR porp, runs great, on YOUR boat! B)

Then YOU will also be a PROP GURU when it comes to YOUR props on YOUR boat!

I know thats right Andy .

this threads getting ambiguous now starting to mill over the same old stuff ( adjustability on a jae) weve been over it enough - The team will say build it as planned everyone else has their own ideas. Not talking bad on Rodney and the guys, Im just saying I was more interested in what could have been learned about props.

I got the pm thanks

you may not like the term Guru but to me you are one bad man when it comes to rc boats, props, and motors

Hugh

 

[RodneyPierce]

I do have another question to toss into this .7 radii stuff. How should people accomplish that on a JAE, with a non adjustable strut?

Umm, make it adjustable? :lol:

Sorry Rodney. h34r:

Touche'

But you defeated the question!!!

 

[Tim Kish]

Andy,

I am saying that most propeller designs that we use for our Hydros

run on the last 30% of the tip of the blade.

There is no outer 70% of the radius.

Greg,

The middle picture looks pretty close to the last 30% in the water.

Thanks,

Mark Sholund

"The middle picture looks pretty close to the last 30% in the water."

:lol: :lol:

What about the 1st pic where the blade is running full depth?? I guess the boat is runnig at a bad attitude there Huh?

Take enough photos of a bouncing boat and you can find just the prop depth you want.

you both have great eyes obviously but tell me how does one start to set it up this (.7) or not (.7) on the table top? lol

I can tell you this if i have to come home to look at photos to set up my boat then go back out to the lake I can see now this will take forever.

Andy and Mark when you guys talk props everyone is a sponge waiting, the only problem is some of the sarcasm may get sucked up too. Most are lost with this .7 radi stuff. Ive been lost since I asked David what he meant by it on the cg thread. I see Im not the only one confused. If you two get into a tech battle here about props it will be over most of our heads and we will be even more lost. Please keep this in mind GURUS.

My eyes and ears are wide openView attachment 36012

I just want to learn from two top people in the game

Hugh

My BEST advice to everyone. Forget the "prop gurus"! Go to the pond and adjust YOUR strut, until YOUR porp, runs great, on YOUR boat! B)

Then YOU will also be a PROP GURU when it comes to YOUR props on YOUR boat!

One of the best quotes I have read in a long time .

Tim K

 

[moparbarn]

So what do you think is going to run faster?

Big dia less pitch or small dia more pitch????

andy, should get out this weekend to test the prop you did for me. maybe i'll have some input on this question, although it may only apply to my boat/engine/pipe combo.........

 

[John Beardslee]

That is what makes boat racing so much fun! So many variables, plus a racing surface that changes continuously! When I started doing props - Stock Outboard & Alky Outboard the guru's at the time were the propulsion engineers at Mercury, OMC & Michigan Wheel, they taught me that in basic terms:

Use the prop diameter to control the rpm range, use the pitch to control the speed & use the blade area to control the weight you are pushing. Weight was difined as hull drag, aero drag & actual mass of the hull. Then the blade shape design gets the water on the blade, uses it and gets it off as fast as possible. At high speed & rpm water is viewed as a calloidal substance like jello. When I started running toy boats 1968, I carried these same basics over to the models. I tried real hard to run stock Octura Props at the time (2.0-2.8 series)but none matched my set up at all. Sooooo I started cutting and twisting and my first was a miniture of one of my better full size outboard props. The hull was a copy of one of my full size neelers (prayerboats as John Bridge always called them) it was a Hugh Enthrop design. Full floating sponsons with adjustable airtraps, what a ride! That thing hung the sponsons 6 inches off the water (100+mph) or is wasn't running. Sorry to get so long winded! Still love the challange of all it.

John

 

[Mike Larson]

Thanks John!... and the knowledge grows..... now.... to the Bat Bench!... mike

 

[moparbarn]

i have to agree with john, most of what i know about setup & props comes from my days in full scale boats. virtually all of it transfers directly to our "little" boats. if you're searching for info, don't be afraid to go to full scale boats sites B) .

 

[John Beardslee]

i have to agree with john, most of what i know about setup & props comes from my days in full scale boats. virtually all of it transfers directly to our "little" boats. if you're searching for info, don't be afraid to go to full scale boats sites B) .

Most of my eperience was with outboards where the weight of the engine was right over the prop and we cupped and added blades to carry that weight. Now days with flex shafts,adjustable struts and sponsons you have the adjustablity with out all the weight on the prop which in some respects makes it more difficult because there is inherit lift in every surface drive setup but not as much weight to off set it. Infinite adjustability can drive you crazy - log your work, make one change at a time, the rewards will be there for those who learn their own equipment better than others know theirs. As much as some would want to make you think this is an exact science - It is not!

John

 

[shoboat]

Mike,

Send me your H-7 and I will fix it for you.

Read post #15 again as I have just posted an update and some

Good information on where to adjust your present propellers for

Better Performance.

Happy Easter Fellas,

Mark

 

[moparbarn]

So what do you think is going to run faster?

Big dia less pitch or small dia more pitch????

andy, should get out this weekend to test the prop you did for me. maybe i'll have some input on this question, although it may only apply to my boat/engine/pipe combo.........

beautiful weekend, upper 60's, sunny & DAMN WIND blowing 20 -30 mph all day long, both days :angry: ! no testing props in that weather........

 

[shoboat]

Robin,

Hopefully you will be able to get out this weekend for some testing. We just tested

a 1452 on a friends JAE-21 yesterday and it ran quite well. The 2014 is next with

an adjustable strut setting.

Have Fun Testing,

Mark Sholund

 

[moparbarn]

not this weekend, mark. i have 3 boats to finish for my first district race next weekend. 1 being an ob jae h34r: .....open water next friday i will try andy's 1460 he did for me. if he's right, i should pick up a few mph without losing much drivability. an 80+mph heat racing 20 boat would be awesome, if i can keep up with it :lol: !