<VV> Whatever happened to the prototype modern fan (plastic?)

[hugo at aruncoaches.co.uk]

Engine speed probably 2,200. But the fan is MUCH bigger and heavier, so 
the scale speed and inertia/momentum is probably similar I would guess. 
But of course they have thermal clutches fitted to cushion the load. 
Maybe that's the answer? Take a load off the belt.

On 2018-02-02 18:28, BBRT wrote:
> Hugo,
>
> Low rpm of big trucks.. some 1800 thru 2500.. Some go up in low 
> 3000's. Race
> versions higher. Potential rpm of performance Corvair engine is what,
> 6000-6500? For racing, up to 7500 rpm. Figure lower fan rpm if 
> pulleys
> changed, currently fan pulley is smaller than balancer pulley 
> diameter.. I
> want it to be light and if plastic, fine with me.. But apparently it 
> is a
> problem...
> Chuck S
> Fredericksburg, VA
>
> -----Original Message-----
> From: VirtualVairs [mailto:virtualvairs-bounces at corvair.org] On 
> Behalf Of
> Hugo Miller via VirtualVairs
> Sent: Friday, February 2, 2018 9:17 PM
> To: virtualvairs at corvair.org
> Subject: Re: <VV> Whatever happened to the prototype modern fan 
> (plastic?)
>
> Well, commercial heavy trucks have plastic radiator fans, and they 
> seem
> to work without falling to bits ;)
>
>
> On 2018-02-02 17:08, kevin nash via VirtualVairs wrote:
>> Yes it is feasible to make this fan from plastic to keep the weight
>> down... it is seriously difficult though to
>>
>> make the thing stiff enough from plastic and or glass reinforced
>> plastic and keep the weight down. Even fairly thick sections made
>> from
>> G10 (fiberglass reinforced epoxy) don't seem nearly as stiff as the
>> skinny
>>
>> .08-.06" thick blades on the magnesium fan. The original Delrin fan
>> turned out a bit heavier than the mag fan did, and one of the few
>> delrin fans that I've heard of that was actually used had cracks in
>> it
>> after 12000
>>
>> miles, indicating that it wasn't even close to being stiff enough 
>> for
>> long term use, and would have needed to be thicker and heavier than
>> it
>> was . The more I've looked into it, the less attractive plastic
>> anything starts looking for a fan like mine- nobody will want
>> something like this if they have a nasty habit of grenading after a
>> few years of sun, heat cycling, moisture and rpms take their toll...
>> even if they didn't weigh anything! Besides that, this fan is going
>> to
>> need to be geared down for most cars, and that is a much better way
>> to
>> deal with fan weight.
>>
>> Kevin Nash
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
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