Message-ID: <002801c38041$e8cbb640$1702a8c0@WorkGroup>
From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2587535@logan.com>
Subject: Re: [FlyRotary] Re: DIE Power Calculations
Date: Sun, 21 Sep 2003 09:11:46 -0400
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: 7bit


----- Original Message -----
From: "Ernest Christley" <echristley@nc.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, September 21, 2003 1:14 AM
Subject: [FlyRotary] Re: DIE Power Calculations


> Ed Anderson wrote:
>
> >
> > Of course, that slide does not tell you anything about the inner
workings of
> > the DIE, come to Shady Bend if you get the chance.  The rest will have
to
> > wait a tad bit longer. I did say it was a teaser!
>
> Ed,
>
> I won't be able to get to places like Shady Bend until I get an airplane
> built, so that's my excuse, but you have me thinking about some other
> recent post.
>
> High HP equates to higher fuel burn.  Where you REALLY want that HP is
> in the climb.  Once you're at cruise, the extra HP and associated fuel
> burn really buys you very little additional speed.
>
> Is the DIE effect controllable enough to get some extra oomph on
> takeoff, and then dissappear at cruise settings?
>


Morning Ernest,

    Good question.  No question higher HP requires more fuel. I agree, about
where you want the HP.  My field in not really short (2300 ft), but with
trees and powerlines off the ends, I want altitude quickly!  My recently
built and installed manifold with the plastic plenum does not provide the
power I got on take off with the old manifold - and I miss it.  I understand
why it does not - Now.

   If you have your induction system DIE tuned to (say 5500 rpm), then when
your engine rpm gets at (or relative close to - say within 150-200rpm of
5500) you will get the DIE effect.  However, once the rpm is either lowered
or raised above 5500 by the DIE bandwith - the effect diminishes until it
disappears.

   However, remember that the fuel flow is dependent also on what rpm and
air fuel mixture I choose.  So at Altitude I can elect to run high power
(higher fuel burn) or less power at any rpm. Well, up to a certain point -
it does takes more power to turn the prop faster, so higher RPM will of
neccesity require higher fuel burn than lower rpm.  At  WOT, I have  hit
close to 200 MPH but that takes a burn rate of approx 12 GPH or I can cruise
at 170 MPH TAS for around 7-7.5 GPH.

DIE does not force or require you to burn more fuel even when at the
effect's RPM.

Another way to think of DIE is that it improves the volumetric efficiency of
your induction system by (amongst other things) reducing power lost to such
cause as pumping losses.  So that means when operating at DIE rpm, but NOT
wanting to produce max power you will get better fuel economy because the
engine is not working as hard (not using as much fuel energy)just to suck
air in.

The DIE effect of and by its self does not produce any power, it simply
forces more air/fuel mixture into the combustion chamber which of course is
what produces the power increase.  But, if you reduce the fuel (lean the
mixture) then it will reduce the power produced - regardless.

Hope that answered your question about DIE. Your rpm variation may take you
in and out of the DIE effect.  You may produce more power at the DIE rpm,
but only if you have the fuel flow necessary  or you may elect to fly at the
DIE rpm without producing more power, but getting better fuel economy.  At
least that is what the analysis indicates to me.

Ed Anderson