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Date: Tue, 8 Sep 2009 09:26:04 -0500
Message-ID: <5cf132c0909080726i4e946fdr2c7578e2d47cb867@mail.gmail.com>
Subject: Re: [FlyRotary] Re: At long last, Second Flight
From: Mark Steitle <msteitle@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Tracy,

My thoughts are that the third rotor causes 50% more drag than a 13B.  And
when hot, the compression is the best due to a fresh film of oil on the
surfaces.  Also, there is one extra compression stroke per rev than with a
2-rotor.  So, when hand propping, you're seeing 8.5 compression strokes per
prop rev. compared to only 5.7 on the 2-rotor.

The more plausible explanation is that you're so weak and wobbly-legged
after riding the wild beast that it feels like it is much harder to hand
prop than when cold (when you're fresh).  In reality, you just need to go
lay down until you regain your strength.  ;-)

Mark

On Mon, Sep 7, 2009 at 7:11 PM, Tracy Crook <tracy@rotaryaviation.com>wrote:

> After plugging the connection to the EFIS1 Pitot port I made another flight
> today.  The OAT was about 8 degrees cooler so - surprise  - my oil & coolant
> temps were about 8 degrees cooler too.  That and a working ASI made this
> flight a lot more comfortable.
>
> I did collect a little more data this time but now I really see the value
> of data logging.   Back on the ground I constantly find myself wishing I had
> written down a different sensor reading under a different condition.
>
> The air temps I'm measuring under the cowl are much hotter than I want to
> see, probably due to insufficient CFM of cooling air.  I haven't measured
> the pressure recovery in my diffusers but indications are that they aren't
> going to be what I was hoping for.  Either that or the pressure under the
> cowl is much too high.   Always in need of more data.  Next flight will be
> made with the dynamic pressure port probe in place under the cowl.
>
> I'm still a little concerned about the high turning resistance of my 20B
> engine when hot.  When cool, it feels normal.  This has not changed in 14
> hours of engine run time.   Any of you other 20B users notice anything like
> this.  Is there any significant difference in the way the engine feels when
> pulling the prop through when hot and cold?
>
> Tracy
>

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<div>Tracy, </div>
<div>=A0</div>
<div>My thoughts are that the third rotor causes 50% more drag than a 13B.=
=A0 And when hot, the compression is the best due to a fresh film of oil on=
 the surfaces.=A0 Also, there is one extra compression stroke per rev than =
with a 2-rotor.=A0 So, when hand propping,=A0you&#39;re seeing=A08.5 compre=
ssion strokes per prop rev. compared to only=A05.7 on the 2-rotor.=A0=A0</d=
iv>

<div>=A0</div>
<div>The more plausible explanation is that you&#39;re so weak and wobbly-l=
egged after riding the wild=A0beast that it feels like it is much harder to=
 hand prop than when cold (when you&#39;re fresh).=A0 In reality, you just =
need to go lay down until you regain your strength.=A0 ;-)</div>

<div>=A0</div>
<div>Mark =A0 <br><br></div>
<div class=3D"gmail_quote">On Mon, Sep 7, 2009 at 7:11 PM, Tracy Crook <spa=
n dir=3D"ltr">&lt;<a href=3D"mailto:tracy@rotaryaviation.com">tracy@rotarya=
viation.com</a>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"PADDING-LEFT: 1ex; MARGIN: 0px 0=
px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">After plugging the connection to=
 the EFIS1 Pitot port I made another flight today.=A0 The OAT was about 8 d=
egrees cooler so - surprise=A0 - my oil &amp; coolant temps were about 8 de=
grees cooler too.=A0 That and a working ASI made this flight a lot more com=
fortable.<br>
<br>I did collect a little more data this time but now I really see the val=
ue of data logging. =A0 Back on the ground I constantly find myself wishing=
 I had written down a different sensor reading under a different condition.=
<br>
<br>The air temps I&#39;m measuring under the cowl are much hotter than I w=
ant to see, probably due to insufficient CFM of cooling air.=A0 I haven&#39=
;t measured the pressure recovery in my diffusers but indications are that =
they aren&#39;t going to be what I was hoping for.=A0 Either that or the pr=
essure under the cowl is much too high. =A0 Always in need of more data.=A0=
 Next flight will be made with the dynamic pressure port probe in place und=
er the cowl.<br>
<br>I&#39;m still a little concerned about the high turning resistance of m=
y 20B engine when hot.=A0 When cool, it feels normal.=A0 This has not chang=
ed in 14 hours of engine run time. =A0 Any of you other 20B users notice an=
ything like this.=A0 Is there any significant difference in the way the eng=
ine feels when pulling the prop through when hot and cold?=A0=A0 <br>
<font color=3D"#888888"><br>Tracy<br></font></blockquote></div><br>

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