To: All F-15-III Owners.

From: Scott Spanburg, MicroProse

Date: 1-22-93

Subject: Authentic Flight Model

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Our Online Rep Quentin, has asked me to try explain
a few things that have been causing some confusion,
concerning the AUTHENTIC flight mode of F-15-III .

1) AIRSPEED
The displayed airspeed is INDICATED airspeed in KNOTS.
(Nautical miles per hour). 1 knot= 1.15 mph.

This is always LESS than or equal to the TRUE airspeed.
Airspeed measurement is basically a pressure
measurement of the moving airstream. The less dense
air at higher altitudes will create a smaller 
measurable pressure difference, hence a lower airspeed
reading. True airspeed can be calculated as follows:

TRUE = INDICATED * ALTITUDE FACTOR.

The factors can be found in the chart below.They are
related to the square root of the air density to
that at sea level. 

2) MACH NUMBER
Mach 1 is the value of the speed of sound in air.
It varies with altitude and temperature.
At sea level it is around 662 knots. (762 mph).
At 36,000' it decreases to 573 knots, after which
it then stays constant to about 70,000'.
The HUD display takes this into account.

3)WEIGHT and ALTITUDE
WEIGHT:
The basic airframe of an F15 weighs about 40,000 lbs.
Add 20,000 lbs of fuel and 20,000 lbs. of ordnance
and it tips the scale close to 80,000 lbs. This
obviously affects the performance of the aircraft.
ALTITUDE:
The density of the air at 30,000 is only 37% that at
sea level. At 60,000 only 9%.
THRUST:
Engine thrust is degraded at higher altitude (not
enough air to combust).

The best analogy I can think of would be this:
Go visit a very tall building. Run up the stairs as
fast as you can. Count the number of steps before you
collapse. Go back the next day and do it again, this
time carrying your twin brother piggyback and note
the difference.

4)ROCKET PILOTS
It has been noted that that the F15 has a thrust to
weight ratio greater than 1 and should therefore be able
to accelerate straight up. Yes, but remember that gravity
is not the only force at work here. Air resistance will
soon slow the plane to terminal "up" velocity and 
altitude will soon after choke off the thrust. The tennis
court sized wings are there for a reason, use them in
conjunction with the engines to your advantage.

HOW TO FLY HIGH AND FAST:
Raise your gear soon after takeoff. 
100% thrust.(No burner). Jettison any bombs.
Go to AA mode and fire all short and long range
missiles. Keeps wings level.
Fly to 15,000 about 20 degrees nose up.
Fly from 15,000 to 20,000 about 7 degrees nose up.
(Airspeed will probably be around 400-450 knots).
Don't pull any unnecessary G's.
Watch your mach number. Keep it above .9M. If you
lose your mach, it takes a long time to get it back.
Fly to 30,000 about 5 degrees nose up.
Fly to 40,000 about 3 degrees nose high.
Fly to 59,000 about 2 degrees nose up.
THIS WILL TAKE A WHILE !!!. Use accelerated time
if you get bored.( It's also a good idea to head away
from hostile areas before climbing).
At 59,000 level your nose and watch your altimiter.
You should be about mach 1.3-1.5. If you desire to
do mach 2, use afterburner.(WATCH YOUR FUEL,esp.
in accelerated time).
The key to climbing and high speeds in any
configuration is not climbing too nose high.Don't
let your airspeed bleed off.

Indicated to True Airspeed Conversion:

TRUE = FACTOR * INDICATED

ALTITUDE   FACTOR

SEA LEVEL  1.0
 5,000     1.077
10,000     1.164
20,000     1.370
30,000     1.635
40,000     2.016
50,000     2.563
60,000     3.259

Ex. Your HUD indicates your airspeed to be 300 knots
at 30,000 feet altitude. Your true airspeed is
 300 * 1.635= 491 knots.

Regards,
Scott Spanburg
F-15 Team
MPS Labs