On 27 Nov. 2016, at 4:28 pm, Steven W. Boese <flyrotary@lancaironline.net> wrote:

Steve,

Laramie Wyoming airport elevation is 7280 ft MSL.

The coolant delta T of ~8 deg F at the beginning of the data plot is a result of the engine having been running for a few minutes before the start of the data plot.  I choose to process only the data for which the Dynon has valid GPS times.  I didn't turn on the GPS until after the engine had been started.

I assembled a pressure logging system with four differential pressure sensors that record pressures once per second to a SD card.  Just as you suggest, I recorded pressures at each exchanger inlet face and inside the cowl near the cowl exit, all referenced to the airframe static source.  In my case, it didn't seem to matter very much where the pressure probe was located inside the cowl.

For me, it is worth the effort to have the pressures recorded automatically since recording the information manually is a distraction and I certainly can't simply remember the data.  This was of particular concern for the first flight.

The figure is of the pressures recorded for the flight referenced in the previous posts.  The pressure for the airframe pitot was calculated from the Dynon airspeed.  The pressure at the cowl radiator is nearly the same as the pressure near the cowl exit since the inlet to the duct to the cowl radiator was closed.  The airframe pitot does not perfectly overlay the other pressures at the end of the plot since the sampling rates of the Dynon and pressure recording system are not exactly equal.

 

Steve Boese

RV6A, 1986 13B NA, RD1A, EC2

<pressures.jpg>

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From: Rotary motors in aircraft <flyrotary@lancaironline.net> on behalf of Stephen Izett <flyrotary@lancaironline.net>
Sent: Saturday, November 26, 2016 2:17 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: flight conditions for HX data

 

Hi there Steve. 

Do you live at the Everest base camp!

The highest peak in Western Australia is 4000ft and its 800miles to my North East.

I didn’t even know it was there till I looked it up just now.

I guess 99% of our land is flat with just a few hills.

Our greatest attraction is at altitude 0. Our beautiful beaches.

Thanks for the data. Even though your environment is so very different to mine its interesting.

How do you start with a scoop Coolant delta of ~8F. 

Looks like your coolant rad gets delta’s of 13-18F in flight.

I suppose I just won’t know how she will go till she flies.

I’m planning to measure pressures relative to static during that first flight.

I was thinking at each Exchanger face, and a few points around the cowl.

My chief concern will be exit area so looking for any positive pressure rise under the cowl.

Your flying and have married thinking with experience so any wisdom from you would be appreciated.

Steve Izett

On 26 Nov. 2016, at 4:10 pm, Steven W. Boese <flyrotary@lancaironline.net> wrote:

Steve,

Here is the flight data for the conditions under which the heat exchanger data was collected.  Three touch and go circuits were executed before climbing to an altitude of about 10500 ft.  The TAS is unstable due to the winds aloft and the proximity to mountainous terrain.

Steve Boese

RV6A, 1986 13B NA, RD1A, EC2

<flight overview.jpg>