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Mon, 10 Jul 2006 15:03:41 -0400
From: "Al Gietzen" <ALVentures@cox.net>
To: "'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] Temperature control
Date: Mon, 10 Jul 2006 12:03:45 -0700
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=20
The issue:
On the ground, cooling stabilizes at 180-190F deg and oil is usually 10
degrees below the cooling with an OAT of 65-70F deg.
When running with higher OAT (75-85F deg) after about 0.5 hours of =
moderate
taxi runs (up to 4300RPM) the cooling temps reach 212Fdeg with the oil =
about
200F deg.
=20
The question:
Can something be done to get lower operating temperatures without
redesigning the system?
Would switching to pure water help and if so by how much?
Would removing the thermostat help and if so by how much?
How much change should I expect if I were to do both?
You guys down south should have a good idea of how best to enhance =
cooling.
What are your suggestions?
Thanks,
Jim Maher(Dyke Delta)
Jim;
=20
Going to pure water will decrease the delta T from rad in to rad out.
Removing the thermostat will increase the flow rate which will also =
decrease
the delta T across the rad. The net effect is increased average heat
rejection temperature at a given power level, and therefore, increased =
heat
rejection. However, without knowing your current flow rate and temp =
drop
through the rad, there is no way to tell how much improvement you'd get. =
=20
=20
But from what you describe, I'd say don't do anything at this point. =
Wait
til your plane flies and see how it cools on climbout and cruise. Your
ground cooling seems adequate to get you airborne. If you have a long =
wait
on the ground; turn your engine off, until you have to move again.
=20
If you want to know the effect of pure water or thermostat removal on =
your
system, you'll have to make the change and see the results.
=20
FWIW,
=20
Al (Scheduled for first flight this weekend; forecast temps upper 90's.
Yikes!)
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face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'> </span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>The issue:</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>On the ground, cooling stabilizes at 180-190F =
deg and
oil is usually 10 degrees below the cooling with an OAT of 65-70F =
deg.</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>When running with higher OAT (75-85F deg) =
after about
0.5 hours of moderate taxi runs (up to 4300RPM) the cooling temps reach =
212Fdeg
with the oil about 200F deg.</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'> </span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>The question:</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>Can something be done to get lower operating
temperatures without redesigning the system?</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>Would switching to pure water help and if so =
by how
much?</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>Would removing the thermostat help and if so =
by how
much?</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>How much change should I expect if I were to =
do both?</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>You guys down south should have a good idea =
of how
best to enhance cooling.</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>What are your suggestions?</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>Thanks,</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>Jim Maher(Dyke Delta)</span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DVerdana><span =
style=3D'font-size:
11.0pt;font-family:Verdana;color:blue'>Jim;</span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DVerdana><span =
style=3D'font-size:
11.0pt;font-family:Verdana;color:blue'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DVerdana><span =
style=3D'font-size:
11.0pt;font-family:Verdana;color:blue'>Going to pure water will decrease =
the
delta T from rad in to rad out. Removing the thermostat will =
increase the
flow rate which will also decrease the delta T across the rad. The =
net
effect is increased average heat rejection temperature at a given power =
level,
and therefore, increased heat rejection. However, without knowing =
your current
flow rate and temp drop through the rad, there is no way to tell how =
much
improvement you’d get. </span></font></p>
</div>
<div>
<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DVerdana><span =
style=3D'font-size:
11.0pt;font-family:Verdana;color:blue'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DVerdana><span =
style=3D'font-size:
11.0pt;font-family:Verdana;color:blue'>But from what you describe, =
I’d
say don’t do anything at this point. Wait til your plane =
flies and
see how it cools on climbout and cruise. Your ground cooling seems
adequate to get you airborne. If you have a long wait on the =
ground; turn
your engine off, until you have to move again.</span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DVerdana><span =
style=3D'font-size:
11.0pt;font-family:Verdana;color:blue'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DVerdana><span =
style=3D'font-size:
11.0pt;font-family:Verdana;color:blue'>If you want to know the effect of =
pure
water or thermostat removal on your system, you’ll have to make =
the
change and see the results.</span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DVerdana><span =
style=3D'font-size:
11.0pt;font-family:Verdana;color:blue'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DVerdana><span =
style=3D'font-size:
11.0pt;font-family:Verdana;color:blue'>FWIW,</span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DVerdana><span =
style=3D'font-size:
11.0pt;font-family:Verdana;color:blue'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DVerdana><span =
style=3D'font-size:
11.0pt;font-family:Verdana;color:blue'>Al (Scheduled for first flight =
this
weekend; forecast temps upper 90’s. =
Yikes!)</span></font></p>
</div>
</div>
</body>
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