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From: "George Lendich" <lendich@optusnet.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2604051@logan.com>
Subject: Re: [FlyRotary] Re: Supercharging
Date: Wed, 19 Dec 2007 07:50:21 +1000
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Ernest,
Sounds interesting to me.
Do you know what air flow you will need - Ed can supply the maths for that. 
For instance you will need 347.2 cfm at 7,500  (+ additional boost) also 
277.6 cfm at 6,000 rpm ( + additional boost). I don't know how much HP the 
blower will rob, but with 600cfm at 6,000 rpm, you will have the extra you 
need there there.
Simple too.
Something to consider would be air temps.
George ( down under)

> The rotary is unique among aircraft engines, in that we have 6000 shaft 
> RPM to work with.  Normally, that is considered a liability, in that it 
> requires an extra gearbox to drop the RPM to a range usable by a 
> propeller;  but, supercharging is a case where I believe we can make some 
> lemonade.
> 6000RPM is about the speed that commercial leaf blowers use.  The blowers 
> just happen to be about the same size as an engine housing.  A 
> conservative blower will easily deliver 600 CFM at 150MPH.  We don't 
> usually want a LOT of boost in an airplane, since that will impact 
> reliability, but how much is a LOT?  The typical supercharger is heavy, 
> requiring some major engineering to produce a reliable mount and drive 
> system.  A turbo carries its own list of issues, not the least of which is 
> blowing the intake air across a hot exhaust component.  A blower, mounted 
> as an integral part of the flywheel and enclosed by the bell housing, 
> would sidestep most of the problems.  It won't deliver a LOT of boost, but 
> neither will it require pop-off valves, waste-gates, intercoolers or a 
> heavy mounting system.  I will consider it a win, if I can get 200Hp at 
> 7000RPM.
>
> Richard Sohn asked me at the Round-up about how would I know if it works. 
> I had to think about that one.  The answer is that I will provide for an 
> alternate air intake (at least temporarily).  I will do a pull test, while 
> running the engine with air being pulled through the blower and through 
> the alternate air intake.  The blower will have to be shuttered in the 
> second test to insure it doesn't rob energy from the system.  That won't 
> give me raw horsepower, but it will give me a solid ratio of power 
> difference between the two.
>
> Any ideas on what I should do, not do, or do differently?  I'm still 
> technically in the planning stages, so I would appreciate any and all 
> input.
>
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