flyrotary@lancaironline.net Mailing List Archive

Thanks Ed.

I guess it would be interesting to see what kind of cooling I get with pure water. I thought Cp was determined by other factors.

Due to the fact that I probably have near 1/2" restrictions (5/8" OD tube, 90 deg bends that flattens the tube somewhat and some weld blobs inside) in the lines to each rad I probably don't have to worry about cavitation.

I built new "flow sensors" using 7/8" OD, 0.8" ID cu tubing with 1/16" OD static and pitot lines. (The one for the left rad has a 3/4" OD insert/extension for the return hose, hopefully far enough from the pitot/static openings to result in 0.8" ID.
3" long tubes; pitot and static openings about 1.25" from output end.

Had a very hard time getting good calibration data. 17 secs to fill a 5 gal bucket. Readings ranging from 8 to 15 "H2O over the six runs in the attached spreadsheet. Maybe bad way to calibrate having the output hose directly down to the bottom of the bucket. Thinking about this garden hose flow sensor to be inserted in one rad return line:
https://www.ebay.com/itm/254837917737?_trkparms=amclksrc%3DITM%26aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3D971e60c290e14d2bb7c58668ab680152%26pid%3D100675%26rk%3D2%26rkt%3D15%26sd%3D124020811161%26itm%3D254837917737%26pmt%3D1%26noa%3D1%26pg%3D2380057&_trksid=p2380057.c100675.m4236&_trkparms=pageci%3Acfa4c425-9737-11ec-a39f-82df1cb73e50%7Cparentrq%3A37715bf717f0a44d43c87084fffe3902%7Ciid%3A1

Probably won't hold up to hot coolant and high RPM pressure but may work to get a base reference?

Still need to do more runs to get air out of the system, but so far looks good. Reading 12"H2O at 2700 RPM (previously determined to be 10+ gal/min), 39 to 44"H2O at 4700 RPM (could be 24 gal/min or 48 gal/min for two rads).

I would really like someone to check my formulas in the WaterFlow.xls spreadsheet. It's based on this formula:
h_w _{(in H2O)} = 0.186 (v_fpm / 60)² where v_fpm = velocity (ft/min).
Vfpm = 60 * Sqrt(Hw / 0.186)
231 cu inch / gallon.
Changing value in cell A2 (tube ID) changes area through which fluid is flowing.

Got it on the model. But certainly the spreadsheet is a very good starting point.

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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