flyrotary@lancaironline.net Mailing List Archive

Finn : I am still building my engine and FFW set-up ,

but this is the fundamentals on coolant flo ,that i got on cooling a 2 Rotary 13 B ,

think that many of these principles is the same on other models too like the Renesis

The coolant - 50% ethylene glycol and 50% water.

The flo must be 35 - 40 gallons per minute through the system at more or less 6000 rpm.

The averaged pump on these flowrates need more or less 3 Hp

The pump can “cavitate” and loose efficiency if there is too much friction in the system , and the flo rate is to slow.

This cooling is based on a heat exhancher (radiator) of 600 cube inch.

I think that the basics is to start with bigger cooling hoses. 40 mm

Try to keep them as straight as possible and avoid bends to the minnimum.

Then the airflo and distribution and heat exhange is a topic on its own.

Included are data and work by Fred Moreno (revised oct 21 1999)

What is interesting in Fred’s work is that a 10 gph increase in coolant flow reduced cooling drag by 15 %

https://drive.google.com/file/d/1JVh3KTa0LyiKQLKmaR4pRpDnLuuA_y17/view?usp=drivesdk

Sent from my iPhone

Le Roux Breytenbach

On 27 Feb 2022, at 18:20, eanderson@carolina.rr.com <flyrotary@lancaironline.net> wrote:

Well Looking at the chart you referernced it looks like the mixture for 50/50 the CP could range from 0.79 at -30F to 0.88 at 100F. IF 100 % glyco then at -10F we have a CP of 0.53 and at 100 0f 0.66. So looks like I picked a worst/best case condition. But, using your example I get a cp of 0.8807. Not a 30% difference but more than 5%

In any case, I would suggest if you find data you feel more confident in, do not hesitate to subsitute it.

Ed
pecific Heat of Ethylene Glycol based Water Solutions
Specific Heat - c_p - of ethylene glycol based water solutions at various temperatures are indicated below
Specific Heat - c_p (Btu/lb ^oF)
Ethylene Glycol Solution
(% by weight) Temperature (°C)
-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100
0 1.0038 1.0018 1.0004 0.99943 0.99902 0.99913 0.99978 1.0009 1.0026 1.0049 1.0076
10 0.97236 0.97422 0.97619 0.97827 0.98047 0.98279 0.98521 0.98776 0.99041 0.99318 0.99607
20 0.93576 0.93976 0.94375 0.94775 0.95175 0.95574 0.95974 0.96373 0.96773 0.97173 0.97572
30 0.89373 0.89889 0.90405 0.90920 0.91436 0.91951 0.92467 0.92982 0.93498 0.94013 0.94529 0.95044
40 0.84605 0.85232 0.85858 0.86484 0.87111 0.87737 0.88364 0.88990 0.89616 0.90243 0.90869 0.91496 0.92122
50 0.79288 0.80021 0.80753 0.81485 0.82217 0.82949 0.83682 0.84414 0.85146 0.85878 0.86610 0.87343 0.88075 0.88807
60 0.72603 0.73436 0.74269 0.75102 0.75935 0.76768 0.77601 0.78434 0.79267 0.80100 0.80933 0.81766 0.82599 0.83431 0.84264 0.85097
70 0.67064 0.67992 0.68921 0.69850 0.70778 0.71707 0.72636 0.73564 0.74493 0.75422 0.76350 0.77279 0.78207 0.79136 0.80065 0.80993
80 0.61208 0.62227 0.63246 0.64265 0.65285 0.66304 0.67323 0.68343 0.69362 0.70381 0.71401 0.72420 0.73439 0.74458 0.75478 0.76497
90 0.58347 0.59452 0.60557 0.61662 0.62767 0.63872 0.64977 0.66082 0.67186 0.68291 0.69396 0.70501 0.71606
100 0.53282 0.54467 0.55652 0.56838 0.58023 0.59209 0.60394 0.61579 0.62765 0.63950 0.65136 0.66321

I'm not sure how

------ Original Message ------

From: "Finn Lassen finn.lassen@verizon.net" <flyrotary@lancaironline.net>

To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

Sent: 2/26/2022 9:29:22 PM

Subject: [FlyRotary] Re: Ed's spreadsheet

From your 24 Aug 2012 post about cooling section in the spreadsheet:

"Cooling mass flow is dependent on:

1. A 0.7 cp compared to pure water of 1.0 Cp - this compensates for the typical anitfreeze dilution of the specific heat of water. "

Roughly weighing a 1 Gal 50/50 antifreeze jug I get maybe 7.9 pounds after subtracting 0.3 pound for the jug). Pure water about 8.3 pounds. That's about 5%.
I realize it changes somewhat with temperature but nowhere near 30% ?

https://www.engineeringtoolbox.com/ethylene-glycol-d_146.html

Difference between water and 50/50 at 100C: 1000/1030 or 3%. Not 30%.

Difference in specific heat (whatever that is): 1.0079 / 0.88807 = 13% (for 50/50 at 100C).

What am I missing?

Finn

On 2/26/2022 10:48 AM, eanderson@carolina.rr.com wrote:

I agree, must have got it from someplace credible - like Bill Shertz.

CP was 1.0 for pure H20 and somewhat less with antifreeze mixed in.

I had a primary pully from MazdaTrix that reduced water pump speed - since engine was turning faster than normal in automobile, did not want to have any cavitation. So my water pump did turn a bit slower than stock.

Not necessarily - note that water flow drops off if pump speed increases into the "caviation range"

------ Original Message ------

From: "Finn Lassen finn.lassen@verizon.net" <flyrotary@lancaironline.net>

To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

Sent: 2/25/2022 10:39:43 AM

Subject: [FlyRotary] Re: Ed's spreadsheet

Thanks Ed.

But 185.85 seems pretty detailed for a SWAG.
Any chance you got it from Bill Shertz's tests (which I unfortunately can't find the posts about)?

What determines "Cp Coolant"?
Heat transfer efficiency from engine to water and water to rad?

From measuring the rims of the e-shaft pulley (122mm) and water pump pulley (112mm) it looks like the Renesis water pump runs a bit slower (factor 1.09 compared to your 1.18).

Should water flow be directly proportional to water pump RPM?

Finn

On 2/25/2022 10:07 AM, eanderson@carolina.rr.com wrote:

Sorry, Finn.

Too much water under the bridge, pretty sure I did not make it up out of thin air. I suspect I visited some pump websites to arrive at a SWAG.

Ed

------ Original Message ------

From: "Finn Lassen finn.lassen@verizon.net" <flyrotary@lancaironline.net>

To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

Sent: 2/24/2022 2:25:56 PM

Subject: [FlyRotary] Ed's spreadsheet

Hi Ed,

From where did you get the 13B coolant flow numbers (Pump Factor)?

I want to be certain that I have adequate coolant flow.

Finn

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