LeSving wrote:
I guess, but with no performance data, I would think there is not enough power left to gain any performance by doing so.
Well, at 10k you still have more than 65% power, which is what a lot of people cruise at anyway.
In the aircraft that I fly (Piper Arrow II – 200hp) 8000ft is the last altitude with a setting shown for 65% power.
After that, the only settings shown are for 55% power. So at 10k, you’re somewhere between 65% and 55% power.
In fairness to LeSving, that’s not a lot of power left over for climbing further.
Well, yes, and a C150 would climb even less – presumably mainly because it has even less excess power.
I don’t know what the NA altitude record is but vaguely recall the Everest summit having been photographed not long after WW1 with an NA engined plane. Obviously one of very lightweight construction. The engine would have been making only about 20% of sea level power.
Peter wrote:
That is utter bullsh*it.
It’s not. At 12k, only half is left. That is not much for a plane that only climb 1000 fpm at sea level.
Yes but one doesn’t need 1000fpm, in most scenarios in GA flying.
It takes me something like 45 mins to reach FL180, which gets me VMC on top in most scenarios in which I am likely to be flying a non-deiced plane. And on a nice day one stops the climb at FL090-100.
dublinpilot wrote:
In the aircraft that I fly (Piper Arrow II – 200hp) 8000ft is the last altitude with a setting shown for 65% power.That’s a bit odd… Both the C172S and the PA28-181 have figures for 75% up to 8000 ft and 65% up to 12000 ft.After that, the only settings shown are for 55% power. So at 10k, you’re somewhere between 65% and 55% power.
That can be the case for a given RPM.
For 75% power at 8,000 ft you would need max RPM, and if the POH does not contain data for this, but only a lower RPM, you don’t have the data. Whether that is an actual limitation, or just a lack of data, depends on the aircraft.
The ceiling is not a limitation, it’s just the altitude at which in ISA condition the ROC is below 100ft/mn, IIRC from CS23.
For 75% power at 8,000 ft you would need max RPM, and if the POH does not contain data for this, but only a lower RPM, you don’t have the data. Whether that is an actual limitation, or just a lack of data, depends on the aircraft
That may very well be the reason for the difference. Performance figures in the manual are only shown for 2100 rpm and 2400rpm (2100 loses 75% power earlier).
The ceiling is not a limitation, it’s just the altitude at which in ISA condition the ROC is below 100ft/mn, IIRC from CS23.
Agreed. This is what is known as the “Service ceiling”. Then the “Absolute ceiling” which is sometimes mentioned is the highest altitude which you can climb in ISA and have no climb rate left.
You may have other reasons why altitude is limited. The DA42 is certified only to 18.000 feet allegedly because of limitation with the turbo. The Columbia 400 has a RoC of 897 fpm at FL250 but in Section 2 of the POH it is limited to FL250 with a FAA-approved O2 installation or FL140 without.
