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From: "Al Gietzen" <ALVentures@cox.net>
To: "'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] Cooling Inlet Areas/Bernie's RV9
Date: Mon, 4 Apr 2005 09:22:59 -0700
Message-ID: <000001c53932$915f0a00$6400a8c0@BigAl>
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Doug;
=20
I agree with your 'rule-of-thumb' numbers. My analysis came up with =
coolant
inlet area in sq. in. of 1/3 the HP (.33) for climb out on a 90F day. =
It
assumes a 120kt climb speed for my Velocity. I used 45% of that =
additional
for the oil cooler. Assumes scoop efficiencies of 85% or better.
=20
Al
=20
-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Shearbond@aol.com
Sent: Monday, April 04, 2005 6:49 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Cooling Inlet Areas/Bernie's RV9
=20
From my work on Compact Heat Exchangers especially as related to my =
friend's
13B powered RV-3, Bernie has plenty of heat exchanger "frontal area" and
"volume". =20
=20
That said, there are two further considerations in the "gotta have" =
category
to be able to confidently taxi out and T/O WOT for as long as one wants =
in
Military Air (+40 deg F over std.) conditions.
=20
First....if cooling air can't get out, it can't get in. That is: =
adequate
air exit area is absolute. The exit area must be sufficient for both
coolant and oil cooling exit air. For 200 HP that is about 2.1(oil +
coolant + now heated air) x .30 x HP or 2.1 x .30 x 200 =3D 126 sq. in. =
total
for 200 HP. =20
=20
Yes, that is larger than an air cooled engine would require but =
investigate
the temperature differentials between a 350 deg F air cooled cylinder =
and a
200 deg F hot coolant and one will quickly realize that there must be =
more
lbs. of air flow for a coolant cooled engine.
=20
Second, even if cooling can get out, if it can't get in, it can't be =
there
to cool the heat exchangers. Rule of thumb: 0.3 sq. in. of cowling =
inlet
air opening per HP. 200 HP x .3 =3D 60 sq. in. Note: This assumes a
reasonably shaped inlet cowl which has been discussed online often. =
IMHO:
Berni's plane inlet shape and inlet cowl is fine, but I question his =
inlet
opening area.
=20
Note: the exhaust area requirement is greater than the inlet =
combination of
oil and coolant due to the now considerable hotter air temperature. =
Rule of
thumb: Coolant air inlet opening for 200 HP coolant cooled engine ~60 =
sq.
in., oil inlet opening ~30 sq. in. equals a total opening of 90 sq. in. =
A
good place to start with exhaust opening is 1.4 times the inlets or 126 =
sq.
in. Close the exit area down with cowl flaps to as little as 80% of the
inlet combination at cruise conditions!
=20
Don't mean to start another stream of threads on an old subject, but we
sweated over this one for 3 months and 3 systems and one might save a =
lot of
time by comparing ones system to these simple "works great" rules of =
thumb
which are the result of LOTS of technical and experimental work.
=20
Doug Dempsey
N6415Q and RV7 in process
Colorado, USA
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<div class=3DSection1>
<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DVerdana =
id=3D"role_document"><span
style=3D'font-size:11.0pt;font-family:Verdana;color:blue'>Doug;</span></f=
ont></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'>I agree with your =
‘rule-of-thumb’
numbers. My analysis came up with coolant inlet area in sq. in. of =
1/3 the
HP (.33) for climb out on a 90F day. It assumes a 120kt climb =
speed for
my Velocity. I used 45% of that additional for the oil =
cooler.
Assumes scoop efficiencies of 85% or better.</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</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 style=3D'margin-left:.5in'><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma'>-----Original =
Message-----<br>
<b><span style=3D'font-weight:bold'>From:</span></b> Rotary motors in =
aircraft
[mailto:flyrotary@lancaironline.net] <b><span =
style=3D'font-weight:bold'>On
Behalf Of </span></b>Shearbond@aol.com<br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Monday, April 04, =
2005 6:49
AM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> Rotary motors in =
aircraft<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> [FlyRotary] =
Cooling Inlet
Areas/Bernie's RV9</span></font></p>
<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>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'>From my
work on Compact Heat Exchangers especially as related to my friend's 13B
powered RV-3, Bernie has plenty of heat exchanger "frontal =
area"
and "volume". </span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'> </span></f=
ont></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'>That
said, there are two further considerations in the "gotta have" =
category
to be able to confidently taxi out and T/O WOT for as long as one wants =
in
Military Air (+40 deg F over std.) conditions.</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'> </span></f=
ont></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'>First....if
cooling air can't get out, it can't get in. That is: adequate air =
exit
area is absolute. The exit area must be sufficient for both =
coolant and
oil cooling exit air. For 200 HP that is about 2.1(oil + coolant
+ now heated air) x .30 x HP or 2.1 x .30 x 200 =3D 126 =
sq. in.
total for 200 HP. </span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'> </span></f=
ont></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'>Yes,
that is larger than an air cooled engine would require but investigate =
the
temperature differentials between a 350 deg F air cooled cylinder and a =
200 deg
F hot coolant and one will quickly realize that there must be more lbs. =
of air
flow for a coolant cooled engine.</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'> </span></f=
ont></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'>Second,
even if cooling can get out, if it can't get in, it can't be there =
to cool
the heat exchangers. Rule of thumb: 0.3 sq. in. of cowling inlet =
air
opening per HP. 200 HP x .3 =3D 60 sq. in. Note: This =
assumes a
reasonably shaped inlet cowl which has been discussed online =
often. IMHO:
Berni's plane inlet shape and inlet cowl is fine, but I =
question his
inlet opening <u>area</u>.</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'> </span></f=
ont></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'>Note:
the exhaust area requirement is greater than the inlet combination =
of oil
and coolant due to the now considerable hotter air temperature. =
Rule of
thumb: Coolant air inlet opening for 200 HP coolant cooled engine =
~60 sq.
in., oil inlet opening ~30 sq. in. equals a total opening of 90 sq. =
in. A
good place to start with exhaust opening is 1.4 times the inlets or 126 =
sq.
in. Close the exit area down with cowl flaps to as little as 80% =
of the
inlet combination at cruise conditions!</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'> </span></f=
ont></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'>Don't
mean to start another stream of threads on an old subject, but we =
sweated over
this one for 3 months and 3 systems and one might save a lot of time by
comparing ones system to these simple "works great" rules of =
thumb
which are the result of LOTS of technical and experimental =
work.</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'> </span></f=
ont></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'>Doug
Dempsey</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'>N6415Q
and RV7 in process</span></font></p>
</div>
<div>
<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
color=3Dblack
face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial;color:black'>Colorado,
USA</span></font></p>
</div>
</div>
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