Working ABC props.

[Ian Inverarity]

Jay,

I am currently running a H-50 with an A-90 powered Hummingbird and getting about 80mph, would a modified H31 be a good prop for me to try? I have a H31 and a pitch guage....

Ian.

 

[Jay_Stone]

Ian,

My traveling partner here has a Roadrunner 90 Ultralight. CMB 1.0 that is tweaked on just a bit --- he can pull a H-50 no problem, and get speeds around 71 mph.... With the H-31 he runs a consistant 73mph. The boat also handles much better with the H-31.

Everyone told him to run a 1667 on the boat. He has also run a 67x114 and likes the H-31 the best.

We are at 3500 feet altitude. We will be heading to Sea Level Next month and we plan to try a few different props on the boat such as a V967/3. I will let you know what happens.

For heat racing on a Roadrunner Style Hull (Which a hummingbird is a direct descendant of), the H-31 is hard to beat. Dont be afraid to cup it up.

 

[David Singleton]

Tim / all

What material do you use to make the anvil of a duplicator ???

Dave

 

[Chris Wood]

JUST THOUGHT I WOULD CHIME IN AND PUT MY TWO CENTS IN ON THIS ONE..

I RUN A CRAPSHOOTER 90 WITH A GREEN HEAD CMB 80 CURRENTLY RUNNING 87MPH... RUN A BEST OF 89.5 SO FAR...

I HAVE RUN THE H-50 H-32- AND SO ON..

I PERSONALLY LIKE THE PROP FROM OCTURA CALL A H667

VERY FAST PROP..

ALSO IF YOU ARE BOUND FOR A ABC TRY A 67 X 114 VERY GOOD PROP.. NEEDS MORE CUP LIKE ABOUT 5.2-5.4 STARTS UNDER 5.0 CUP

 

[TimD]

Tim / all

What material do you use to make the anvil of a duplicator ???

Dave

Dave,

I'm going to give this stuff a try

http://www.selleys.com.au/selleys/live/me....te.home&FFFF208

Cut and paste it into the browser.

I made a duplicator of a stock H49 last night and I'm going to give it a try on the weekend.

Tim.

 

[EatMyShortsRacing]

Chris,

I have a pair of H667s which are destined for my twin 90 when it arrives..

hope they work on that...

EMS Racing (Craig Chenco)

 

[Ian Inverarity]

Chris,

I am running an A-90 which would not rev as hard as your 80, so I dont think the H667 would load up the motor enough to get any good speed. i have heard that the H667's are good for 80's tho, and I know a fellow boater who runs twin 80's and sometimes uses them. Any recommedations for 90's?

Craig,

Buy bigger props for those A's. Start with H50's..... You are getting the right pipes I hope.... ;D

Ian.

 

[EatMyShortsRacing]

Ian...

H50s you think??? what about the H31s??? Thats going to be my main problem... matched pairs of props...

And what about pitching up the H667s???

Yes I will try the Bolly pipes... pity they dont look any better than they do...

EMS Racing

 

[Ian Inverarity]

Craig,

Of all the props I tested on the weekend the H-50 was 10 k faster than the best of the rest.... launched easily and handled great 8) I think I will pull my pipe in to see if I can get even more speed on the same prop.

Pitched up H667's? Might work, I may try to get hold of one to play with.... ;D

I didn't try my H31. Just checked it out on the pitch guage this morning, it looks like a 1470 with a texas cut and cupped tips. Most of the prop is under 4 inches of pitch. But it does have a lot of diameter. Since it sounds like thay may work, I have a couple of 1475's to play with too.... ;D

The dull brown isn't that attractive is it? His old pipes used to be made with a lot less resin that was a little green so they were black with a greenish tinge, but would leak too much.... But they dont get that hot compared to metal pipes. Maybe you could paint them (do it before you use them tho). You could get the same green you use on the sponsons! Probably not such a good idea....

Ian.

 

[Slideblues]

H-31 with mods:

 

[Slideblues]

H-31 stock:

Pics from RC Fastprops and Paul G.

 

[TimD]

Gene,

What was done to the "worked" one other than polishing it?

I'm told the H31 doesn't have much pitch at all - did it get "persuaded".

Tim.

 

[Slideblues]

H-31 specs stock,

Dia. 2.680"

Pitch 4.00"

Cup 5.0

Hang on and I'll go get the mod specs,

Gene ;D

Nothing said about pitch, but it was cupped out to 6.2

 

[Ian Inverarity]

Gene,

Pitch measurement is a complicated business, would you know than angle that was measured to get 6.2" ie I generally measure my props in sections of 5 degree angles, which often gives quite different reading to what pitch or cup people state.

Ian.

 

[Slideblues]

Blades looked slimmed down a bunch to me, check out the thickness comming off the hub of mod vs. stock

Gene ;D

 

[Ian Inverarity]

Gene,

That's because the H-31 was based on the fairly chunky 1470! But considering the problems I am having bending props, chunky is just fine! 8)

Ian.

 

[TimD]

Gene,

But considering the problems I am having bending props, chunky is just fine! 8)

Ian.

Ian,

Stainless H50's ;D

Tim.

 

[Slideblues]

;D I agree on the pitch measurement, unless everyone uses the same gauge, and methods, the variables are always there.

Gene ;D

 

[Ian Inverarity]

Gene

Exactly, for example I can measure over 7" of cup on a stock H50 but they only rate them as 5.7" cup. People are telling me cup a 1667 to 7", but what does that mean???? ???

Tim,

Dale rang me yesterday! Sweet!!! 8)

Ian

 

[Slideblues]

First from Paul G.

Average blade pitch,

And this from Chris Hicks on measuring cup,

Take three readings 10 degrees apart, cup numbers are always higher than the pitch or average pitch that you are looking for.

And from Denzils using a dial indicator model with a sharp tip for better accuracy,

The tip of the prop is doin 75% of the work at speed on a surface drive.

Take a stock H-31 and run it with a tach and GPS, thats the baseline, then pitch the tips up to 6" (5" stock) and run it. RPM's will drop and speed will increase.

And here is my spin on the subject,

Answers you get depend on who you ask and the gauge that they use.

Another difference is if the prop is constant pitch, like the Octura 1400 series,

or progressive pitch like the Prathers or X series Octura's.

Seems like I remember that Jim Schaefer told me that the H series had progressive pitch.

Constant: the pitch is the same across the entire blade face.

Progressive: the pitch is lower at the leading edge and increases towards the trailing edge.

I think I am gettin a headache,

Gene ;D