Speed on FSX SE default Bombardier Learjet 45

[Stanley777]

Hi everyone,

 

In the last several days I have been flying the FSX SE default Bombardier Learjet 45 quite a lot, and thus been getting to know its capabilities.

 

According to the information provided with the program, its cruise speed is 464 kn. According to the entry on Wikipedia, 463 kn is this plane's maximum speed, and its cruise speed is 445 kn.

 

But when I push my jet much past, oh let's say, 335 kn, I get an over-speed warning. Thus, I am not able to attain anywhere near the velocity that the real Learjet 45 should get.

 

Does anybody know what is going on?

 

Thank you.

 

Stanley

[mrzippy]

[Reference Speeds]

flaps_up_stall_speed = 112.0 //Knots True (KTAS)

full_flaps_stall_speed = 102.0 //Knots True (KTAS)

cruise_speed = 464.0 //Knots True (KTAS)

max_mach = 0.81

max_indicated_speed = 330 //Red line (KIAS)

 

'nuff said?

[StringBean]

Does anybody know what is going on?

 

I do, I do!!!

 

Cruise speeds will be True Air Speed (TAS) in knots, (KTAS).

 

Your airspeed indicator is Indicated Air Speed (IAS) in knots, (KIAS).

 

Some reading for you- https://en.wikipedia.org/wiki/Airspeed

 

peace,

the Bean

[Stanley777]

Hi everyone,

 

Thank you for your responses. Let me read that Wikipedia article carefully, and then I 'll see if I can get the issue straight.

 

I keep hearing about these different speed concepts, but I have still not absorbed the lesson.

 

But I do want to make certain of this -- the fact that I am getting an over-speed warning when the aircraft is at about 335 kn does not mean that I have a problem. This is supposed to happen, right?

 

Stanley

[mallcott]

Hi everyone,

 

Thank you for your responses. Let me read that Wikipedia article carefully, and then I 'll see if I can get the issue straight.

 

I keep hearing about these different speed concepts, but I have still not absorbed the lesson.

 

But I do want to make certain of this -- the fact that I am getting an over-speed warning when the aircraft is at about 335 kn does not mean that I have a problem. This is supposed to happen, right?

 

Stanley

 

Yes,

 

And the Learning Center in your sim provides answers.

[StringBean]

...the fact that I am getting an over-speed warning when the aircraft is at about 335 kn does not mean that I have a problem. This is supposed to happen, right?

 

Only if you want to rip the wings off of the plane. :pilot:

 

Pull the thrust lever or yoke back, or both.

 

In other words, slow down.

 

peace,

the Bean

[noah]

Stanley, you DO have a problem! You are flying too fast! The wiki article will explain it i'm sure but let me try it in simple terms.

 

There's a couple things to understand:

 

1. As you gain altitude the air gets thinner

 

2. The airspeed indicator displays the airplanes speed through the air. This instrument is calibrated for NORMAL SEA LEVEL air pressure.

 

3. The speed displayed on the GPS displays the planes speed over the GROUND.

 

When sea level pressure air rushes into the airspeed indicator pitot tube, it displays a speed. Imagine if the air were half the pressure - the speed displayed would be half - even though you are going just as fast. As your jet climbs, the airspeed indicator starts to display a much slower speed then you are really going because the air pressure outside is much lower than it was at sea level. Try this experiment: Fly up to 35,000 feet and set your speed for 250kts. Now look at the GPS. You are actually flying 450kts!

 

When people say the cruise speed is 450kts, they are referring to the groundspeed, NOT the speed shown on the airspeed indicator. That speed can only be achieved in the thin air at cruise altitudes (30,000ft+) - There's your answer why airliners fly so high.

 

Now the Learjet has a limit of 330kts on the airspeed indicator. At no point can the speed displayed on the Airspeed indicator go over that, otherwise you will get an overspeed warning. If you were flying at sea level, The Indicator would show 330kts, and the GPS would show 330kts. Up in the cruise altitudes 330kts Indicated would be close to 600kts on the GPS.

 

When going from point A to B in the Learjet, go up to around 35,000 feet (highly variable) and set the speed to around 260-270. When you look down at the GPS you'll be doing your 445kts cruise speed.