Content-Type: TEXT/HTML; charset=UTF-8 Content-Transfer-Encoding: quoted-printable How about you fill in a field with the values you have, but all= ow the user to change it. I will measure my Dt and would be able to use t= hat.

No doubt it could stand improvements for sure,= =20 Jeff.

There are four DT's I employ in the cooling=20 equations. Change in air temperature across the radiator, chang= e in=20 air temperature across the oil cooler and change in fluid temperature = of=20 the coolant and oil as they flow through their heat exchanger. &= nbsp;=20 I have heard of Air DT= across=20 the radiator ranging from 50-100F, I am currently using a DT of 70F , but I know that Tra= cy has=20 reported a<= STRONG>=20 DT of 100F. I am also using DT of 70F for the oil cooler and tha= t is=20 probably too high. For both fluid DTs, I am using 16F.

IF anyone has reference material or sources that co= uld=20 help me refine those figures - it would undoubtedly improve the coolin= g=20 section.

As Jeff pointed out for the cooling section there i= s no=20 input for OAT although there is for the power section. My initial tho= ughts=20 would be to pick

some OAT and I'm thinking of 59F (SL stan= dard=20 day temp) as a nominal mid point of&nb= sp;=20 DT. Then if OAT is above that DT, then to simply subtract the differen= ce=20 between OAT and 59F and reduce the air DT across the radiator by that amount. = =20 Conversely if OAT is below 59F then to add that DT to the 70F I am currently=20 using.

By increasing the DT factor more heat is transferred (better co= oling)=20 by reducing the DT fac= tor less=20 heat is transferred (worst cooling)

IF anyone has reference material or sources that co= uld=20 help me refine those figures - it would undoubtedly improve the cooling=20 section.

Edward L. Anderson
Anderson Electronic Enterpris= es=20 LLC
305 Reefton Road
Weddington, NC 28104
http://www.andersonee.com
http://www.eicommander.com

From: Jeff Whaley

Sent: Friday, August 24, 2012 11:49 AM

To: Rotary motors in aircraft <= /DIV>

Subject: [FlyRotary] Re: [flyRotary] Spreadsheet Cooling=20 Section

Ed, you did say he cooling chart is not quite where it= should=20 be =C2=85

Plugging some numbers in there is very interesting; ho= wever,=20 not to be too critical but I think the constants used to calculate HP Vs OA= T Vs=20 Cooling Capacity are a bit fuzzy.

For example, at any RPM, AF, HP, simply increasi= ng the=20 OAT value in the spreadsheet results in improved cooling capacity =C2=85 My= =20 installation=C2=92s capacity to cool was much more influenced by OAT than t= he=20 resulting change in HP due to OAT . I had no cooling problems at 50F = but=20 had big problems at 100F =C2=85 The spreadsheet indicates opposite.

Jeff

From:

Ernest=20 Christley

Subject:

Re:=20 [FlyRotary] Spreadsheet Cooling Section

Date:

Fri,=20 24 Aug 2012 10:41:30 -0400

To:

Rotary=20 motors in aircraft=20

<= BR>
<= /SPAN>

Ed Anderson=20 wrote:

= > But, as state= d=20 before the cooling section is on less solid ground due to
> the fact that= =20 installation variables play such a large role in cooling
> and they are = not=20 taken into consideration. But, you can play with it to
> see the effec= ts=20 of changing several variables on cooling.
>=20
> Ed
>=20

= Just been playi= ng with=20 this, pulling data out of my data logs. I don't have all my num= bers=20 exact yet, but I think this
will be useful = for=20 making a SWAG at determining if the system will stay within safety ma= rgins=20 during various phases of
flight.<= SPAN=20 style=3D"FONT-FAMILY: 'Courier New'; FONT-SIZE: 10pt">

= Would it be to = much to=20 ask those with flying machines if they can go out and determine where= =20 their system starts to warm
up, which would= be a=20 rough indication of where the cooling capacity is exceeded? I= =20 thinking of doing a steep climbout
and slowly drop= ping=20 the nose until the temps start coming down, noting the temp, MAP, air= speed=20 and AFR at that point. I
don't think it = is=20 necessary to tell grown people that built their own airplane that the= y=20 need to be careful about
airspeed while = doing=20 something like this. If we can get a variety of samples,= we=20 can put error bars around the
numbers that th= e=20 spreadsheet gives.=

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