Overspeed Issue

M

Macruairidh

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I have a question. The Bombardier Learjet 45 has a cruising speed of around 500mph. Why is it the I keep getting an overspeed warning every time I set my auto pilot IAS to 350? None of the Jet aircraft in my FS2004 can go faster than 350 without an Overspeed warning except for the f-18 I downloaded and I get an overspeed with that at 450. I hope someone has a solution.
 
Do you have AccuFeel installed?

It may be limiting the overall speed of your aircraft. It limited by A2A P-51 Civilian to 250 MPH, and after I reset the sliders I can now do 400+ as it should.
 
check your groundspeed.... if i recall the AP works on IAS whereas most performance figures are Ground Speed.... was the first thing into my mind...
 
Matt is right, but the IAS is also measured in knts not mph.
There is quite a difference at high speeds.
 
I think I found it. In the aircrafts config file, the Max Indicated Speed is set to 330 so I changed then to the rated make speed of the aircraft and I can cruise at 400+....Thanks again everyone...
 
The cool thing about FS is we can do just about anything we want with it.

If you are happy with your changes enjoy them but they are wrong.

[Reference Speeds]
flaps_up_stall_speed = 112.0 //Knots True (KIAS)
full_flaps_stall_speed = 102.0 //Knots True (KIAS)
cruise_speed = 464.0 //Knots True (KTAS)
max_mach = 0.81
max_indicated_speed = 330 //Red line (KIAS)
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Let me try an explain why.

Note I took the liberty of changing the first two comments to KIAS from KTAS.

Stall speed is relative to the air moving over the wing so those speeds will always be indicated speeds.

Cruise Speed is always represented by True Airspeed. The problem is no one ever tells us at what altitude that applies.

Cruise speed and maximum speed will always happen at some altitude where the air is thinner (thus reducing indicated air speed) and the engines still produce sufficient power.

In this case the structure of the aircraft is limited to 330 KIAS anything over that will result in aircraft damage this is the VNE or never exceed speed. As you go higher the air becomes thinner thus creating a condition where you are flying faster than the air is indicating over the structure. The thinner the air is the less the drag is on the airframe. So at some altitude you will be able to go about 464 kts while the indicated speed is well below 330 kias.

However without getting into the speed of sound discussion also note that you are limited to .81 mach. As you go higher the speed of sound becomes slower and you will approach the max mach number before you ever get close to the max indicated number. If you go high enough max mach may prevent you from going 464 kts.

When you fly a jet with auto throttle (or by hand) you fly by max indicated speed up to 18,000' above 18,000' you fly it by max mach. You will need to use caution when flying against the barber pole from probably 16,000 to 20,000. Its very easy to bump into the max/IAS limits at those altitudes.

So the original numbers were right you were just flying too fast too low (or possibly too fast too high).

Note most jets are fastest in True Airspeed between 20,000' and 30,000'. Rest set your aircraft to the original values and try flying at those altitudes. Keeping in mind the 18,000 rule set your auto throttle for less than 330 below 18,000 and below .81 mach above 18,000. Watch how close you are flying at those maximum numbers. A good wind shift will throw you into overspeed fast.
 
The fastest cruise speed for the Lear 45 is achieved at 43,000 feet altitude. Do not exceed mach 0.81. Ground speed will vary depending upon wind aloft speed and direction, so if you are flying into a headwind, your ground speed will be slower.
 
The 747s that I fly cruise at about 500 knots at altitude, which is aout M.85 typically and maybe around 300 KTS IAS depending on altitude and temperature. Because the air is thinner at altitude the indicated airspeed is much lower than the true airspeed. The limit for airspeed in the CFG file is an indicated airspeed value. The overspeed values are structural in nature, the IAS value is tied to the air flow pressure on the airframe, the Mach value to the effects of approaching the speed of sound and compressing air in front of the structure as well as control issues. Mach is related to the speed of sound, which decreases with decreasing temperature.
pt
 
fliger747 said:
The 747s that I fly cruise at about 500 knots at altitude, which is aout M.85 typically and maybe around 300 KTS IAS depending on altitude and temperature.
Click to expand...

.85?
Isn't that a figure from happier days or are transcon/-at/-pac fliers excempt from all too strict fuel consumption regulations?
 
Bjoern said:
.85?
Isn't that a figure from happier days or are transcon/-at/-pac fliers excempt from all too strict fuel consumption regulations?
Click to expand...

If you fly Ryan Air it certainly is!
Michael O'Leary is one of the most successful business people on this planet! (But still a twat!).
I suppose you saw the documentary about their fuel calculations!?
 
stuartcox said:
If you fly Ryan Air it certainly is!
Michael O'Leary is one of the most successful business people on this planet! (But still a twat!).
I suppose you saw the documentary about their fuel calculations!?
Click to expand...

Nope. I already care way too much about this airline than I should. And not in a positive way.
 
Matt Wynn said:
welcome to the Ryanair Infrequent flyers club then :icon_lol:
Click to expand...

Make that the "Infrequent Flyers" club.

But when I did/do/will do any travelling by air, it won't be on Ryanair. Its competitor with the "E" is just as cheap and flies to real airports to boot.
 
We fly at speeds directed by a cost index, or by a filed Mach number for oceanic crossings. A CI in the 25-35 range will give M.830 or so, A CI of 200 about M.855 and a CI of 600 M.865 or so. The plane will merrily cruise at M.90.... Most Oceanic crossings are filed at M.84. The plane is actually designed for and quite efficient at M.85. That works out to about 505 kts TAS. Varies with temp and altitude. Planes such as the 737 are much slower, the 747 is still the fastest civil transport.

T
 
that sounds very similar to the the sailing terms of Actual Windspeed and Windspeed over the Deck....grants the speeds are much slower....I am not a serious flyer on FS9, Just want to enjoy it once in a while and the Overspeed was on my nerves....I flew my Challenger 604 from the Bahamas to Dover at 450 kts and no overspeed for a change....But I will always take my sailboat over a plane any day. much more enjoyable.
 
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