Mailing List flyrotary@lancaironline.net Message #12702
From: Al Gietzen <ALVentures@cox.net>
Subject: RE: [FlyRotary] Re: EWP Info
Date: Mon, 8 Nov 2004 11:58:38 -0800
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message

Bob won't let me banish anyone, so maybe a good beheading instead  :-)

 

O-o-o-o; ouch!

 

I’m not saying you can’t run to higher power – in fact, I’m sure you can.  The key word is “safely”, and maybe one should add “long-term”.  Unless you are measuring some internal temps, how do you know when you start getting boiling around the plugs, or high thermal stresses in other areas?

 

That's an interesting point.  Of course I can't prove there isn't boiling at a local hot spot with the stock system.   Do you know if this was Mazda's criteria for setting a flow rate from the pump? In other words, do we need some particular flow rate to avoid localized boiling?  

 

I have no way of knowing.  Without further information, I’m going to assume that even though we are only talking about 1.5%, or less, of the engines output, the Mazda engineers aren’t going to design in a bunch more flow than needed.  But of course there are different flow requirements for the same rpm at different powers, so I guess I’d also assume that, for this aspect of cooling at least, things would be OK for something close to WOT at a given rpm.

 

As I’ve suggested before, I don’t see saving power consumption as a reason for considering an EWP, especially considering the losses in converting mech energy to electrical and back again.  But for redundancy and/or configuration reasons, OK.  Just be sure that with the EWP you have sufficient flow rate to avoid cooling system problems (internal and external), and be prepared to provide significant current to get it.  It just ain’t no free lunch.  The rated flows and current draws from the makers are just too good to be true, so they likely are not.  The laws of physics still apply.  The only way you are going to get 55 gpm with 10 amps (or whatever it was) is to help it along with no pressure at the outlet, and probably some positive pressure at the inlet.

 

Al (I swear I will not say another word about EWPs; that beheading thing is just too scary)

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