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Old January 8th 05, 12:19 AM
Chuck
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Thoughts: The big triangular hole under the Cherokee 140 cowling for
the cooling air exhaust is a tremendous source of drag. I would guess that
the fiberglass cowling on my airplane is the source of most of the speed
change between the 140 and the 180 airplanes. 20 extra HP just shouldn't
change the speed that much. The 20 extra HP also shouldn't make that much
difference in climb performance; I suspect that the much wider chord
prop on the 180 makes a big difference at low speeds. The 180 prop pitch
is also a climb prop pitch, and it can't be changed - it will easily make
redline RPM at any altitude I've flown at. Both 140 aircraft have cruise
props though I don't know the details.

I'd be happy to arrange a demonstration if anyone's in the area.


No demonstration, but I'd sure like to talk about those numbers.

I purchased an older 180 ('63) about six months ago. She's great for
her primary purpose -- traning. She can climb at ~1000 even in our
San Antonio summers. Four people, temps in the low 90s this past late
summer and she's still going up at 900FPM. So, I agree with that.

I haven't had the opportunity to look up the exact type, but I
strongly suspect a climb prop (not original -- changed in '92).
That's based on performance. It climbs great compared to a 140 and a
140/160mod I've flown. But my speed is horrible compared to those
numbers you quoted.

At ~70% power, I'm lucky to get it to 110knots. The only way she ever
gets into the yellow is decending with power still on!!!

You mentioned the cowl with the big trangular hole in bottom -- well,
that's what I've got. And to make it worse, there is a lip that stick
downwards around the front of the opening -- creating even more drag.

I also saw someone else mention a replacement cowl that improved
airflow, dual exhaust (instead of muffler in front of the firewall),
and less drag. Is that what you have on your 180???



Chuck
N7398W