On Dec 28, 2:03*am, Bertie the Bunyip
wrote:
On Dec 27, 3:37 am, 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?
Terry

The temp correction.. WAT will give you the info you need.

Well I can do the temp correction and calculate density ht ,then I
would have to forget all about about going across the graph
horizontally like it says to and just treat the climb wt limit graph
as totally separate to the others, and me thinks I will do that from
now on, but then it aint pressure altitude that I am plotting, so I
will also have to cross out the word pressure and replace with
density. I really think the author of the graphs ( and the text
book ) should be doing that, rather than a little old PPL from
downunder with barely 200 hrs of mostly puddle jumping to his name.

Also, the correct term is altitude, not height. height is how high you
are above the ground, which is kind of meaningless in calculating your
performance.

Yes , I was a bit sloppy with terms there, point taken ( I was
definately referring to altitude)
Thanks