Re: [CAD_CAM_EDM_DRO] Re: Model Boat Propeller

turbulatordude wrote:

>--- In CAD_CAM_EDM_DRO@yahoogroups.com, NEVILLE WEBSTER
><nevillewebster@...> wrote:
>
>
>>hi Dave,
>>
>> maybe you could get the basic dimensions from an off the shelf
>>
>>
>propellor and adapt it to suit your size requirements - of course this
>may not be the most efficient in the water but it would be your own
>design and manufacture.
>
>
>>
>> I would be glad to help with the 3d modelling - STL file for milling
>>
>> Neville
>>
>>
>>
>>
>
>If it's not too much trouble, I'd be interested in a smaller version
>of a propeller. I want to make a small brass fan (propeller) to use
>on the ceiling fan cord. one pull chain would be a fan, the other a
>lightbulb. that way, one would know instantly what was being pulled.
>
>As for propellers, I know that airfoils are listed in some registry.
>I have seen kit planes with the airfoils listed as some 'NASC' design.
> forgot the actual letters. do propellors have some similar registry ?
>
>
>

It is NACA, the forerunner of NASA. National Advisory Committee for
Aeronautics.
Back in the 40's they ran tens of thousands of airfoils through a wind
tunned and
published charts of the results, alsmot like the FBI's fingerprint
classification
system. You put in the thickness to chord ratio and some other
measurements,
and it comes out to a multi-digit code. You go to the NACA file and
pull out the
sheet with the closest code number, and it has all the performance
measurements
on that airfoil. That exhaustive data is still in use today.

There might be a similar scheme for hydrofoils, or maybe just a scaling
calculation to
convert from air to water.

Jon