density ht, pressure ht and landing charts.

On Dec 27, 12:11*pm, terry wrote:
On Dec 28, 4:26*am, "Robert M. Gary" wrote:



On Dec 26, 7:37*pm, terry wrote:

Air density is criticial to aircraft performance, which is why it
surprises me that both Piper and Cessna Landing performance charts
show the climbout weight limit as a function of pressure height and
not density height. *As I understand it ( at least from Australian
Regs) the aircraft needs to have a minimum climb gradient of 3.2% in
the event of a go around being required. *Surely the achievable climb
out gradient must be density ht dependant. *I dont think I have a
problem with the the understanding of what pressure and density hts
are and how to determine them, but I cant reconcile my understanding
of what they are with the performance chart. *.Am I missing something
here?

The Cessna and Piper POH's I have include both pressure altitude and
then a correction for temp. Its probably easier that way (at least
before computers) since the student doens't need to computer density
altitude. You just follow the chart with the pressure altitude and
then move over to the temp on the cahrt.

Thanks Robert, I dont actually have the POH , only a copy of the
landing and take off charts which are copied directly from the flight
manual ( from the flight school, it is not my aircraft) . As I say my
text book has the same chart, It is has 4 graphs , The bottom left
square has as you say both *pressure altitude on the y axis, which you
take across horizontally to intersect the temperature to go up to the
required runway distance ( makes sense) *BUT you are then ( according
to my textbook example) supposed to take the pressure altitude line
horizontally across to the climb wt limit graph on the bottom right.
which is therefore not temp corrected. Does that make sense? ( a
picture would be useful here)- Hide quoted text -

You are suppose to move up/down as a result of both the temp and the
weight. I don't have a copy of the chart in front of me or I could
give a better description. However, I will admit that these charts can
be very confusing.

-Robert