flyrotary@lancaironline.net Mailing List Archive

On Fri, Mar 23, 2018 at 7:35 AM, Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:

Hi people

I know how much I have appreciated data over the years so for those interested here is some more.
Having looked at last weeks test data and the temps looking like they were close to stabilised after reaching around 212F I thought I would risk it and see what the temps did get to.
The temp senders are calibrated accurately up to boiling point (within <1F at 212F) but I’m not sure how accurate they are up at 225F.
The graph below is 43minutes of repeatedly (12 times) taxing and then running down our ~1000yard strip at between ~20-37knots
The OAT was 74-77F during this test.
Renesis 4 port RD1C EC3 EM3 Elect Adj Prop
Water cooler is 540in3 (custom dual pass) with inlet of 20in2
Oil Cooler is 193in3 (mazda rx7 turbo) with inlet of 7.5in2

I’m wondering what a 30row oil cooler like Tracy uses might do to both the oil and water temps.
We will press on and hopefully flight test it as soon as we have it licensed.

Cheers

Steve Izett

Hi Steve,

Steve Boese has posted some of his pressure differential data on a Mazda cooler. He was seeing a really large oil pressure drop across the cooler, indicating highly restricted flow through it. Less flow=less cooling. Have you measured oil pressures on the inlet and outlet?

As Tracy has mentioned in the past, short bursts of power won't really tell you much relative to sustained high power. Too many variables: inconsistent heat input, and inconsistent air flow for cooling (varying speeds). Since you have a controllable prop, have you tried tying the plane down & doing a sustained run at, say, 75% power? Surely the plane would get off the ground using 75% power, so if you can cool with static (only the prop) airflow into your heat exchangers, flying speeds will only help with cooling mass flow through the coolers.

Are you the one using a Maximite to gather your data? If so, would you be willing to share your code? I can handle most things electronic, but I'm not any kind of coder at all. :-)

Charlie

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