An interesting read (as copied from http://www.voyagerairlines.com)
Flight Simulator
Aircraft Performance Evaluation Procedure (FS-APEP)
Years ago, I learned that "freeware" and even packaged software aircraft for MS Flight Simulator can have performance characteristics markedly different from the real aircraft they are modeled after.
I don't look at this as a bad thing. Every new aircraft I install on my PC is an opportunity to flight test a "new" aircraft.
I have developed a method of quickly assessing the capabilities of new Virtual Airline jets, and I thought some FSINN readers might benefit from it.
This is NOT a complete flight test routine. It is a baseline series of measurements so you know what your aircraft is capable of.
CLIMB and CRUISE test:
PREREQUISITES:
Panel with GPS (or test must be conducted at a field with a VOR on site and DME in the aircraft), Elapsed time clock, and fuel flow indicator(s). Knowledge and use of autopilot hold functions will help you a great deal.
Start the test with your aircraft on the runway FULL of fuel.
YOU NEED PENCIL AND PAPER
"CRITICAL NUMBERS"...NOTE your:
MET (Mission Elapsed Time) (should start at ZERO, 0:00)
FUEL QUANTITY (in LBS)
FUEL FLOW (in PPH, pounds per hour)
ALTITUDE (Start the test near sea level)
RATE OF CLIMB (should start at zero, duh)
DISTANCE (from start point, should start at zero) (USE GPS or VOR/DME)
Record your "Critical Numbers" regularly throughout the flight for future reference.
PRESET your AUTOPILOT for:
HEADING: runway heading or whatever you wish.
AIRSPEED: 240 knots IAS
ALTITUDE: 50000 feet (this is just to make sure you don't level out before the test is done)
VERTICAL SPEED: 3000 FPM (initial for most jets), 2000 FPM (for turboprops)
Before takeoff, engage: HDG HOLD, VS HOLD, ALT HOLD, AUTOTHROTTLE and AIRSPEED HOLD.
DO NOT TURN ON AUTOPILOT MASTER YET!
ADVANCE the Throttle to TO thrust. (You don't know your V2 speed (YET) so use a long runway and do your best not to crash.)
At TO/GA thrust stabilize the aircraft in GEAR UP, FLAPS UP climb at approx 3000 (or 2000 FPM), and engage the AUTOPILOT MASTER. It should take over and stabilize the jet on a 3000 FPM climb, at 240 KIAS, on the heading you selected.
PAY ATTENTION to your N1 % RPM! This is a critical portion of the test.
After the autopilot stabilizes at 240 KIAS, 3000 FPM. Notice your N1 RPM.
N1 should be less than 90%
If it is NOT less than 90% reduce your climb rate by 500 FPM.
NOTE (WRITE DOWN) the altitude, distance from start and MET for EACH step of climb rate reduction.
As you continue your climb WATCH your N1.
As it requires 90% or more to maintain a climb rate, decrease it by another 500 FPM.
WRITE down all the critical numbers (see above) at each step.
IMPORTANT: The point at which it takes MORE than 90% N1 to maintain at least 500 FPM climb is a VERY good initial cruise altitude. This may not match up with the text books for your jet, but in my experience it works great in FS.
(RESET your AUTOPILOT - ALT HOLD for this altitude)
Once you establish your initial cruise altitude. Write down the critical numbers again.
Figure up (AND WRITE DOWN):
1: How far you've come (distance from start)
2: How much fuel it took to get up here (Start Fuel Qty minus Current Fuel)
3: How much fuel do you have left (in total pounds)
4: How fast am I consuming fuel (Pounds Per Hour)
5: What is my GROUND SPEED (From GPS or VOR) (for now holding at 240 KIAS)
6: DIVIDE the Fuel Quantity you have now by the current Consumption Rate (This lets you know how many hours you can cruise at the ALT and Airspeed)
7: MULTIPLY that number (of hours) times your GROUND SPEED. (This tells you how far you can cruise in the current conditions)
8: ADD that distance (from #7), to the distance you've already come from the start (from step #1). (This will tell you a very good number for use as your maximum planning range for this aircraft)
FACTS:
This is a conservative range number. Your ultimate range will be greater than this.
---Your fuel consumption will decrease as you burn off weight.
---Altitude "step ups" throughout the flight usually save more fuel. (CLIMB approx 2000 feet for every 25% of total fuel that you burn off.) (use 1000 ft/25% steps for turboprops).
TEST EACH AIRCRAFT (if it is capable) at 260, 280 knots IAS cruise (OR whatever recommended AS or MACH numbers you have based on the real aircraft) and refigure your range numbers. Use whatever cruise speed gets you the best economy / range.
(You don't have to do the climb test over & again. 240 is "almost" always right. Just let the jet re-stabilize at whatever airspeed you choose and figure the range based on you initial cruise point.)
KEEP your climb chart for future reference. It is now an official flight test document.
OTHER USEFUL TESTS:
V2 Test:
At 3000 feet MSL (or less) stabilize the aircraft in level flight, on autopilot with auto-throttle, at 220 knots.
Extend gear and flaps (usually 5 degrees or 1 notch) to configure the aircraft to TAKEOFF setup.
(EXTERNAL VIEW from the side will help greatly for this test.)
Decrease AS hold by 10 knots and let the jet stabilize.
Continue to step down your airspeed until the "nose up" attitude is takeoff attitude.
(USE external view, DO NOT let the TAIL get below the LANDING GEAR)
THIS is a good V2 speed for this aircraft at it's current weight.
I usually do this test at least twice (once at 90% FUEL or more and once at 10% or less)
This will give you your V2 range at min and max weight, you can interpolate other V2's
Approach Speed Test:
Same setup as V2 test above except configure the aircraft for LANDING.
(You may do this test at 1/2 flaps, full flaps, flaps 30, 40, whatever landing configurations you wish. Each result will be different.)
(LET ALL AUTOPILOT induced oscillations clear before you take a reading!)
Approach speed is 10 knots ABOVE the speed at which the tail of the aircraft is ½ way between normal ground "level" and "tail bump" attitude.
Do this test at 90% and 10% fuel and interpolate other speeds.
I hope somebody gets some benefit from this routine. I use it for every new aircraft.
Kevin Chambers,
KC in TCL
FA0033 ( Florida Air)
Formerly GA1961 (Gulf Atlantic Airways)
