<VV> My new experimental fan

[Mike Kost]

Would a solid ring mounted on legs bolted to the engine cover bolts that 
would have a minimal clearance to the fan with a soft gasket to the 
shroud sealing the inlet from the outlet help with efficiency?

Mike Kost

On 11/12/2017 12:50 PM, kevin nash via VirtualVairs wrote:
> Hugo- yes, it is heavier, and it certainly would have been nice for it to be closer to the stock magnesium fan weight, however, compared to the earlier steel fans, this prototype is still a very light fan- those things weighed something like 4.5 lbs (!). All of the stock fans have extremely poor efficiency, resulting in both
>
> less than ideal output and way too much horsepower usage.... all of them use between 8 and 9 horsepower at 4000 rpm, when they ought to be using less than half of that. It is simply impossible for the stock fans
>
> to get to what is considered a normal, expected efficiency of around 60% because of the open shroud
>
> design- air is flung out in all directions simultaneously, and continuously, basically causing all of the blades
>
> to use an excessive amount of horsepower and be unusually sensitive to flow blockages, vs the more normal blower/scroll arrangement where only a tiny fraction of the blades are open to the exit at any given
>
> moment. One of the seriously attractive features of a backwards curving fan is that they experience a very
>
> small, efficiency drop when run open... but this claim HAS to be tested, and tested again... If I don't see
>
> a big enough efficiency gain, then the little bit too heavy weight of this particular prototype will be the least
>
> of my problems.
>
>      Assuming that the efficiency is more like what is expected for a fan like this (60%+), and the output
>
> is what I expect, and the performance can be verified by other competent testers, then I can worry more
>
> about the method of manufacture and material and get the weight down to more like what it should.
>
> If it was made from Magnesium, it would weigh roughly 11 ounces, and printed from composite it would
>
> be around 7-8 ounces, but will require significant re-design for stiffness. I don't want to do that until the
>
> design is thoroughly proven.
>
>      Kevin Nash
>
>
> ________________________________
> From: Hugo Miller <Hugo at aruncoaches.co.uk>
> Sent: Sunday, November 12, 2017 9:04 AM
> To: kevin nash
> Subject: Re: <VV> My new experimental fan
>
> It’s the weight – or rather the rotating mass – that would concern me most.
>
> From: kevin nash
> Sent: Saturday, November 11, 2017 8:58 PM
> To: Hugo Miller ; virtualvairs at corvair.org
> Subject: Re: <VV> My new experimental fan
>
>
> Thanks Hugo!
>
> This particular fan weighs nearly exactly 2lbs. If the shop that machined it had been able to cut it right exactly to my CAD model, it would have weighed 1.4 lbs, compared to the stock Magnesium fan weight of 1.2lbs. While it would have been nice for the fan to have been lighter, I'm certainly not complaining about the weight... this is a prototype, and fan weight is not a concern for me as this time. The output and efficiency are though and this fan is perfect for testing those attributes.
>
> For what it is worth, if this fan had been made exactly to the model, but made from magnesium, it would
>
> weigh around 11 ounces !
>
> Kevin Nash
>
>
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