Inquiry Props

[Chris Thomas]

In similar regards to Grims post for wanting help in tracking the geometry of some performing racing hulls. I have often wondered why there hasn't been a chart or graph of the props we use and where the different manufacturers items would compare in a diameter to pitch ratio. In a diagram or listing. I would like to actually have something that had a comparison in equal terminology . For instance of ie."where a Prather 215 (or ABC) would be in relation to an Octura 1440 or is it closer to a X440". This has been on my mind for a long while. I have even started to catalogue the info for some Octura wheels. My biggest wonderment for some years now is also. Why don't mfgs. list the blade area somewhere? I believe this could be just as important as pitch vs. diameter ?? Most of us change "series" of props to acheive, basically blade area and shape. Giving different performance. I think it would be easy to follow or pick a new prop that was just at the "next step" of the current prop that would run-out half way through the back straightaway. Any ideas?? Or if some one has done this I would like to see the information. Thanks Chris

 

[shoboat]

Chris,

I have detailed a lot of propellers, but how would you figure blade area ratio

of a propeller? I have plenty that someone could detail. I think the charts that

I have made would be very helpful items too many that want to take the next step.

I just don't have the time right now to publish all of my charts.

Great Idea Though,

Mark Sholund

 

[Chris Thomas]

The best way I could describe this Mark is like back cutting a prop. This affects two different properties of the prop. 1) it removes blade surface - removing resistance to turn (less water back pressure). 2) it removes (changes) cup from the trailing edge. again lessening the forces or "free-ing it up". tip spins at same speed - no negative affect to top end, and less blade frees up the prop at lower speeds - gain gain.

 

[VansRacing]

The best way I could describe this Mark is like back cutting a prop. This affects two different properties of the prop. 1) it removes blade surface - removing resistance to turn (less water back pressure). 2) it removes (changes) cup from the trailing edge. again lessening the forces or "free-ing it up". tip spins at same speed - no negative affect to top end, and less blade frees up the prop at lower speeds - gain gain.

Chris,

I have found that after you max out your setup, the prop is the final tweek to pulling your setup together and is different for each model (even models from the same manufacture). Your chart may bring you to a over-all performance / dimentional window for a certain prop but the final step to bringing out the "WOW" in your setup will be knowing how to and where to put that final few thousanths of a inch change in your prop.

I started learning a lot about props once I started investing in prop working tools such as a Prop Pitch Gage made by "Woods".

Grim Racer hooked me up with them and I have purchased and made many other prop measuring tools and prop working tools since then. The Chart idea will help you but my advice would be to use only your own known data.

I keep charts for every prop I make or modify.

I have seen some really nasty looking props kick everyones BUTT! Tommy Lee could take a prop that looked like he had beat it out with a Boy Scout Hatchet and lap the field with it.

For what it's worth....My2Cents

-Carl VH

 

[Chris Thomas]

You are definately correct about the prop being the transition... But, I am not looking for custom stuff. I am aiming for quantifying the stock props from all the prop makers. Like, which props are the same (duplicates) and which prop increases from where the last prop left off. How big is the jump between wheels and does another mfg. fill in the gaps?

I just thought that someone might have catalogued model boat props before and didn't want to duplicate work. Especially if the effort has already been done!