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Mon Jan 09, 2012 11:57 am

Looking for the mfgs contact information in order to purchase tops and bottoms for fitment of aerospace (uber-efficient) blades. Any leads would be appreciated.
Thank you...

Tue Jan 10, 2012 8:09 am

The last one I bought (a few months ago) was VW of Mexico.
I am sure someone else makes them by now though. I'd love to see more info on your project. Is this something you are planning on making multiples of?

Tue Jan 10, 2012 10:26 am

rkeller wrote: Looking for the mfgs contact information in order to purchase tops and bottoms for fitment of aerospace (uber-efficient) blades. Any leads would be appreciated.
Thank you...
Unless you plan to make thousands of them, just buy a fan and take it apart. The 3 pieces are just held together by twist tabs.

Tue Jan 10, 2012 8:47 pm

Hello-

Tell me more about your fan. Are you making a lighter (carbon fiber) fan, a more efficient fan, or both?

Cheers,

Paul

Wed Jan 11, 2012 5:04 pm

We want to change out the C or cupped blades with a double airfoil blade that looks like an S. It puts Bernoulli to work by passing the incoming air over an airfoil by creating a low pressure area just past the leading edge then as the air continues to travel inward towards an even lower pressure cell created by increased space as the blade distance increases towards the outer edge of the circumference. Then the second hump on the next blade does the same thing again to increase the speed of the exiting air. Air cooled Franklin engines and some helicopter and turbine engines use this. Modeling based on the engineering work at Franklin showed a 6% increase in horsepower while improving the air flow on average 11% (varied with speed and air temp) So the thought was to have the vanes stamped out and tacked into existing fan hubs. I've got some pictures and technical information I would be happy to share. The patent was up on this years ago so I'm investigating the economic viability of producing these. If someone else would like to tackle it I would be happy to share the information. I do like the carbon fiber idea, I just have no knowledge of fabrication in that area. It wold lend itself to a more efficient airfoil than standard stamp and die manufacturing would permit.

Wed Jan 11, 2012 7:23 pm

i was wondering what effect removing every other blade would have.they might possiably need to be about 2 times as long but should release some hp to the wheels & still cool fine.but thats not on paper just in my cluttered up head.I guess I need to make a airflow dyno.

Wed Jan 11, 2012 7:41 pm

They actually tried that. They also tried different angles of attack, blade spacing, different shapes and sizes. Lots of really smart people have been working on this and there is a lot of data to chew on but with the efficiency of fan blades have definatey improved and should offer the air cooled community more horsepower, quieter engines, and better gas mileage. We are not talking huge gains but realistically gains of 5 to 6 percent have been shown in other areas, mostly aerospace.

Wed Jan 11, 2012 7:50 pm

it is great to see someone working on this. i had been wondering about a more efficient fan but had no idea where to even start looking for info let alone how to apply it.

would the 11% airflow improvement mean that you could fit a power pulley and still have the same cooling as a normal fan at full speed?

please keep us in the loop with how this goes. i for one would love one.

Wed Jan 11, 2012 8:34 pm

If you increase the air flow through the fan you must increase the amount of air available in the engine bay. Taking more air from the engine bay and sending it through the fan can create a negative air pressure in the bay robbing air from the carb(s).
I have been using a Porsche gen/alt pulley for years in order to speed up the fan for additional cooling while living here in the extreme heat of the desert summer.
In order to provide an increase in pressure in the engine bay I have a 4" air scoop under the Bus forcing in available air under pressure.
Just my 2c.

Wed Jan 11, 2012 10:17 pm

I seem to recall reading the Jake Raby was working on a new fan.

Casey

Thu Jan 12, 2012 4:49 am

Das Dragon wrote: If you increase the air flow through the fan you must increase the amount of air available in the engine bay. Taking more air from the engine bay and sending it through the fan can create a negative air pressure in the bay robbing air from the carb(s).
I have been using a Porsche gen/alt pulley for years in order to speed up the fan for additional cooling while living here in the extreme heat of the desert summer.
In order to provide an increase in pressure in the engine bay I have a 4" air scoop under the Bus forcing in available air under pressure.
Just my 2c.

Excellent point, it may be better to design a version of the fan for the same CFM but with less of a HP drag on the engine.

Thu Jan 12, 2012 7:01 am

If you are going to go through the trouble of manufacturing the blades and assembling it why not stamp out the side plates yourself too? It couldn't add that much more difficulty into the process.

Thu Jan 12, 2012 7:18 am

maybe make them from Al or Ti to reduce the inertia.

Fri Jan 13, 2012 7:31 am

Aluminum is a very practical solution that would withstand the RPM demand and also lower the inertia reducing the amount of initial HP required to turn it.
Titanium would be cool but I don't think anyone would want to spend the money. It would also require special over-curved dies because it tends to snap back into it's original shape so you have to over bend it in order for it to be the shape you want, unfortunately even then there are differences in each piece.
Here are a couple shots of an early (very early) fan with dual airfoil blades. It was designed before most people could even spell Bernoulli. The engineering notes stated "the drag was greatly reduced when we ran the fan blades backwards, it even produced a positive airflow through the test fixture" that was the start way back in the 1930's.

You can see the basic S shape in this unit that was initially found on the largest V12 Franklin aircooled engines.
If I can't get access to the Brazilian or Mexican factory that stamps out the pieces then I'd have to look at machining dies here. As any machinist knows the expense isn't in making each part. It's in the set-up (tool and die) work, and if there is no market this is all academic...

Fri Jan 13, 2012 10:00 am

There may very well be a market for a high performance fan who's efficiency can be supported with real testing.

For a quality, long-lasting hot-street pump gas 180hp VW engine, it cost about $5k these days to build it yourself. $7k-$9k for someone to build it for you. There is your market, those guys.

If you can really move the same CFM for less parasitic loss for a net increase of 6% power, that is a pretty significant number. What performance engine builder wouldn't spent say, $300-$600 to get 6% power gain in a ACWV hot-street engine? At the $3000 price point, you'd have few if any takers.

It's already been suggested, but for the prototype and test phase of your project, you'd be months ahead by salvaging the end plates from new Brazilian fans, that only cost $30 or so.

Fri Jan 13, 2012 1:22 pm

Hello-

Regarding the market, don't forget the 356 crowd. While they're few in number, they have (relatively) deep pockets.

Cheers,

Paul

Fri Jan 13, 2012 2:34 pm

gimmesomeshelter wrote: Hello-

Regarding the market, don't forget the 356 crowd. While they're few in number, they have (relatively) deep pockets.

Cheers,

Paul

Thanks Paul didn't think of that.
I just looked up pictures of those. From a fluid dynamics standpoint, they leave little to be desired. The lightening holes punched to reduce the weight probably do more to reduce flow by upsetting the laminar flow of air then do the shape of the 16 blades. It looks like there is much more improvement that can be done on those than on the stock VW fan. Like another poster mentioned the CFM should probably not too change much lest it rob air from the carburetors, what we'll focus on instead is reducing the HP needed to obtain the engineered CFM for proper cooling.

Fri Jan 13, 2012 5:55 pm

I would think the holes were a tuneing and anti cavatation type of thing,getting the amount of air when you needed it.at low rpm more air would beable to pull through the holes freeing up some pressure/power, and higher rpm more flow,or possiably the other way around so it has plenty of air at low and some slip at higher rpm.not sure witch it does but thats been my take on that,not to lighten the assy.pluss it helps with alt/gen cooling pulling air through them as well.could also be for the thermo stat flaps,so as to releave pressure when closed.be nice if there were enginerneering books from the early days of this stuff(vw&porch).since it is a cyntrifical fan there may be a few different approches to tuning the blade for optinum performance.(and that is deffenatly not my aera,kinda like my spellen,) or possiably somethen more like a turbine wheel.

Fri Jan 13, 2012 6:26 pm

I always wondered if some sort of inlet spike/volute [probably the wrong term] to direct air in to the fan would improve flow.

Casey

Fri Jan 13, 2012 8:18 pm

earthquake wrote: I always wondered if some sort of inlet spike/volute [probably the wrong term] to direct air in to the fan would improve flow.

Casey
A velocity stack is something like that, it lines up the airflow, reducing votices and helps smooth the airflow entering the device, like a carburetor, so that it can have even pressure with no dead air pockets or high / low pressure zones which would result in non linear mixing of the air & fuel. There is a device like that made for VW cooling fan intakes.
http://www.awesomepowdercoat.com/Venturi_Ring.html