Performance O-360 at altitude

[ghostflyer]

Well yesterday was pure fun . The weather has been a limiting factor on flying around here due to tropical storms etc. the weather was coastal so I headed inland for some clear weather . It was time for some figures in performance from a Lycoming O-360. The aircraft was just under full tanks and me at 220 lbs. about 10 lbs of junk in the back. So from sea level to 5000ft it took about 4.5 mins. Then from 5000ft to 10,000ft it took about 10 mins due to cylinder head temperature hitting 410 degs. I will limit my CHT only to 400 degs . My rule . However on a climb at 80 + kts the CHT drops to about 360 degs.
when levelling out at 5000ft , the GS was 120 kts and the ASI showed 100kts. The OAT was 0 degs C. Fuel flow was 9.5 us gals/hr. CHT 380 degs, EGT 1370 degs.
Now comes a question that I can't answer AND I doubled checked the following figures twice.
When levelling out at 10,000ft , the GS was 130 kts and the ASI showed 115 kts. "However"the OAT had jumped to 5 deg C This [all figures]was doubled checked and checked again . Fuel flow was 9.5 us gals /hr CHT was 380 deg but very slowly dropping a degree every 3 Minutes . EGT was 1324 deg. But fuel flow could be leaned out further I think to about 8.5 us gals /hr with extended time.
Full throttle height was expected to be 7500 ft but experienced it at 8000ft plus. But there is a little ram effect due to where the air intake is etc. The aircraft can climb at around 1200ft a min normally at this weight . Some times a lot less due to temperature [OAT].
Total flight time 2.6 hours . The propellor used is a sensenich fixed pitch 60ins . This has proven to be a very good all round prop to use.

[blueldr]

What is the diameter of the 60 inch fixed pitch you are using, please?

[ghostflyer]

The prop is 76 in in dia

[blueldr]

Thanks for the above. I was curious because I used a 76" x 60" FP prop on my TCM IO-360 mod for the first year before I switched to an 82" McCauley CS.
I was happy with the simplicity of the FP prop and it worked just fine, especially up in the Idaho back country where the hops were generally short.
However, a long cross country trip to Texas and return and the generous offer of the CS prop from a friend convinced me that I needed to make a change.
The CS was a good fit for long trips but for back country flying the FP was thriftily adequate and considerably lighter. I also had and, tried, a 76" x 50" FP but found the pitch too thin for general use. It gave me lots of RPMs for T.O. and climb,but it turned too fast in a rather sluggish cruise speed to feel comfortable to me..
I'm sure that you will quickly realize that the extra power is EXACTLY what the C-170 has always needed.

[swixtt]

those all seem like good numbers... what was the question?
i see very similar in mine.

[ghostflyer]

One of the questions was why at 5000ft the temperature was 0 degs and at 10,000ft the temperature was 5 degs and my figures at that height didn't seem correct. I felt fuel flow should be a little lower and CHT a lot hotter.

[canav8]

One of the questions was why at 5000ft the temperature was 0 degs and at 10,000ft the temperature was 5 degs and my figures at that height didn't seem correct. I felt fuel flow should be a little lower and CHT a lot hotter.

Flying through a temperature inversion.

[swixtt]

I see it quite a bit around our area. -15c on the ground 3000 and 0c at 7500ft. pretty unlikely at your location

[MoonlightVFR]

Very simple answer to a portion of question.

Colder air is heavier.

Once I experienced 30 degrees at altitude and minus 49 degrees on ground.

Northway, Alaska 1979

Always expect a little higher temp at altitude.

Ask the true Alaska pilots, they know.

[ghostflyer]

well another flight today and this time with my O2 bottle. The other week when I went to 10,500ft my O2 levels in my blood stream was down to about 85% . So I clawed my self to 13,500 ft and the flight characteristics of the aircraft were very soft. ASI showed about 93kts . I had a heap of clear air turbulence at odd times . It wasn't comfortable . CHT was 350 degs . EGT was 1432 degs. Oil pressure was up 67 PSI.[ Normal oil pressure 63 PSI] Oil temperature was 182 degs. Nearly normal as it sits on 180 degs.
Ground speed around a set triangle course showed a constant 132 KTS. OAT was - 10 degs and that heater well only warmed the toes. This is the second time I can think of using the heater. No real reason for using a heater in my part of the world. Fuel flow was down to 28 liters a hour . This surprised me as I was cruising at 130 KTS and sucking only 28 liters a hour. Time to get from 10,000ft to 13500 ft , well it seemed like all day but about half a hour but my climb was interrupted by a plastic drink bottle crackling that I had drunk and crushed at the start of the flight. The noise of it crackling frighten the hell out of me . I was going to see the surface ceiling of my aircraft but it was just too cold for me as I was only wear a T shirt and shorts . The heater is only a toe warmer . Next time I do this I will have a heap of warm clothing on .

[DaveF]

I've had my airplane over 15000' several times, and it was nowhere near the service ceiling. Maybe you need a constant-speed propeller?

[ghostflyer]

At 15,000ft how did you keep warm . What sort of heater do you have ? I was so cold at 13,500 it was effecting my judgement and body movements . As I,said I would gone higher but it was pilot performance that was lacking . I can't remember what the rpm the engine was pulling .

[DaveF]

My airplane has an Avcon with the single big muffler and shroud feeding a normal B-model heater. I don't think that's the difference, though, because it's still not much of a heater. I guess I was wearing warm clothes because I always do when I'm flying over the mountains, but minus 10 C (14F) just isn't that cold. And the sun at 15000 keeps the cabin pretty warm.