20 Hydro Prop Question

[Tom David]

On 20 hydros, are CNC aluminum 7075 props up to the challenge of heet racing coupled with

high performance nitro engines?

Also Magnalium 7075 alloy.

When I say "up to the challenge" I am asking if they will break.

Tom David

 

[shoboat]

Tom,

I would stick to the newest ABC Propellers if you want

better handling and performance. I have not seen too

many good CNC propellers that did not cost an arm

and a leg recently. I think most just do not use the right

material to start with? Tooling is expensive, and good

material will wear down the tooling. Pretty hard to beat

a few of Jim's latest designs on a 21 and 45 Hydro.

I can share with you we have had some really good results

testing the new GT-21 with the 1900 series of ABC Propellers.

Great lap times and very consistent handling in the mid 70's

for heat racing set ups.

Good Luck Testing The New Boat,

Mark Sholund

 

[Chris Wood]

the first question to be asked is what motor and pipe combo.. because that plays a pivotal role in what prop selection you can run

 

[dwilfong]

Depends on the transitions that are made when you machine them. A stress riser is the weak point. Not the material.

 

[Tom David]

At the present time I am defiantly planning on running H-5 & H-7 on my JAE 21 and tune my engine and pipe from there.

Wasn't planing on running any 7075 CNC props because I don't think they will hold up.

The reason I posted this subject was the listing of a CNC 1450 aluminum prop on ZippKits web site.

That raised my curiosity if anyone else was using 7075 alunimum CNC props for heet racing.

Just thought I would start a discussion about this subject.

 

[Tom David]

Tom,

I would stick to the newest ABC Propellers if you want

better handling and performance. I have not seen too

many good CNC propellers that did not cost an arm

and a leg recently. I think most just do not use the right

material to start with? Tooling is expensive, and good

material will wear down the tooling. Pretty hard to beat

a few of Jim's latest designs on a 21 and 45 Hydro.

I can share with you we have had some really good results

testing the new GT-21 with the 1900 series of ABC Propellers.

Great lap times and very consistent handling in the mid 70's

for heat racing set ups.

Good Luck Testing The New Boat,

Mark Sholund

Thanks for your input Mark.
Down the road, I am going to test other ABC props that have showed promise on the JAE.

I like your post because you do share your thoughts on what has been working for you.

One thing I have learned in this hoddy, there are so many variables on what works for each individual set up.

And each individual set up is what it's all about.

Tom David

I would like to add one more thought about testing.

I personally like to measure my boat's performance by lap times and not a radar gun.

 

[Tom David]

Depends on the transitions that are made when you machine them. A stress riser is the weak point. Not the material.

David, very valid point made by your post.

I do feel that metallurgy is still part of the equation though.

Tom David

 

[dwilfong]

I have run a few CNC props and almost all of them cleaned off the blades but one. This one I ran hard for 4 years racing it and testing on my .45 mono.

What stopped me from using it was a buoy strike. It did not break just took a chunk out of the leading edge.

It was made of the same material as all the other ones from the same maker. But it had good transitions on the cuts made at the hub juction.

Gust figured I would share my experience with it.

 

[Tom David]

I have run a few CNC props and almost all of them cleaned off the blades but one. This one I ran hard for 4 years racing it and testing on my .45 mono.

What stopped me from using it was a buoy strike. It did not break just took a chunk out of the leading edge.

It was made of the same material as all the other ones from the same maker. But it had good transitions on the cuts made at the hub juction.

Gust figured I would share my experience with it.

David, thank you for posting your experiences with CNC props.

This is exactly what I was hopping to discuss on this thread.

I am curious, can you share what alloy your props where made of ?

Tom

 

[dwilfong]

You will have to ask Andy Brown I am not 100% sure what he used.

There is a old tread with lots of info on it.

Even Andy was surprised this prop lasted like it did.

Here are a few picks of this prop.