# Re: So easy a caveman can get this

On Nov 19, 7:58 am, "Koolchi...@xxxxxxxxxxxxxxx"
<john.kulczy...@xxxxxxxxxxxx> wrote:
On Nov 18, 10:53 pm, Mark <blueriver...@xxxxxxxxx> wrote:

Ok, I went ahead and combined the 2
into a new problem, which, for this group
is impossible to not know the answer, and
you know why?

---

Given a mean sea level designated as A,
if a distance of 1,173 ft is required for a
plane to take off when the temperature is
73 degrees F, and 1,356 ft when the temp.
is 86 degrees F, then what distance is required
when the temp. is 79.5 degrees, and given
a different elevation (B) in which a distance of
1,173 ft. is required for takeoff when the temp.
is 70 degrees F, and 1,356 ft.when the temp.
is 80 degrees, then at 75 degrees, what is
the difference in takeoff distance between
the two elevations?

---
Mark

Is the relative humidity the same in both cases? Relative humidity is
rarely the same for two locations even if they are at simmilar
elevations. so even if the jest of your problem is to explain the idea
of "sameness" for a and b, in reality they are different due to other
factors.

My point here is to never fly "air Mark".- Hide quoted text -

- Show quoted text -

Relative humidity is not the correct nomenclature
when communicating the conditions to be considered
for aviation. The proper way to distinguish these flight
variables would be expressed as "density altitude".
Humidity is not considered by pilots. In my problem
I expressed both variables in terms of "altitude",
which is the only way it can be considered, and
it is spot on exact.

Density altitude is perhaps the single most
important factor affecting airplane performance.
It has a direct bearing on the power output of
the engine, efficiency of the propeller, and the
lift generated by the wings.

You see John, as air temperature increases, the
density of the air decreases. Or, as altitude
increases, the density of the air decreases.
As humidity increases, the density of the air
decreases.

That's why I said ALTITUDE, because...

the density of air is described in aviation
as referring to a cooresponding ALTITUDE,
therefore the term used to describe air
density is density ALTITUDE.

To avoid confusion, remember that a decrease
in air density means a high density altitude,
and an increase in air density means a low
density altitude.

Density altitude is determined by first
finding pressure altitude, and then correcting
this altitude for nonstandard temperature
variations.

So my point is, your ignorance of how
humidity is factored into my math problem,
"Air Mark", will more than likely get you
killed.

Also, there is no such word as "simmilar".

Best wishes,
Mark

.

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