Seasonal cruise performance changes

[Bryan Cotton]

Hey guys,
During phase 1, mostly in winter, I came up with a figure of 3000 RPM, 100 kts, and 4GPH. Then we had our top cowl pin incident. The borrowed prop was completely different. When we got our prop back from Lonnie, we needed more like 3150 RPM to maintain 100kts. I figured something had changed in the prop.

So now fast forward to the present. It's cold out! The ground temps have been under 40F on our last few flights. That 3150 RPM now gives us 110+ kts and 3000 is more like 100 again.

In my years of flying I've never really noticed a change in IAS at low altitudes. But now I think I'm seeing it. Anyone else notice this effect?

Also all my temperatures are cool and takeoff/climb performance is much better!

[MichaelFarley56]

Environmental factors make a big difference on my Waiex as well. In addition to engine temperature changes (cylinder head temp and oil temp mainly), outside air temperature can affect my cruise speeds to 5+ mph or more between summer and winter seasons.

Now that your engine is broken in Bryan, be ready to cover your oil cooler with foil tape (or similar) to get oil temps up to "normal" levels.

[mike.smith]

I love flying in the winter! With me and 10 gallons of fuel, I often climb out at 1,200 fpm or better. Much better performance all around. A hot day in the summer could be 400 fpm with the same load.