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jmhelms

Aircraft Maximum Speed Issue

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Using P3D2.2 with W-7 Home Premium...I am having trouble

with a couple of planes where I get get "overspeed" warnings

at speeds below what the stats show to be maximum speed

...I have tried adjusting  the maximum speed in the Aircraft.cfg

file under the "reference speed" section to no avail....so, what to

do?.....alternatately, how to turn off the "overspeed" warning?

.....thanks for any help....John H.

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I guess it would best to ask if you understand the difference between True Airspeed, Indicated airspeed & ground speed? 


Rob Prest

 

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Hi Felx...I probably do not precisely...please explain and

then relate your answer to my question...I'm

"all ears"...

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The maximum speed changes depending on altitude.  You cannot achieve 400 knots in an airliner at 35,000 ft.  You should be using the Mach number at high altitudes and that would normally be in the low to mid .74-.77 mach.  It will show up on the speed tape as about 240-280 kts.

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Hi DiaJohn....thanks for the reply...with all due respect,

I do not understand how your reply relates to my question

...any further clarification appreciated...

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As an aircraft climbs in altitude... the value of IAS drops even if the value of TAS or Mach remains constant for the aircraft.

 

In short... 250kts IAS at sea level is not the same as 250kts IAS at 30,000ft.


Ed Wilson

Mindstar Aviation
My Playland - I69

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Hi John,
 
In the graph, a true air speed (KTAS) of 210Knt gives an indicated speed (KIAS) of 189Knt as measured by the instrument at 7000ft for the current air conditions (density). The air at this altitude has less impact force on the pitot sensor.
 
 
ktaskias.jpg

...so travelling at 210 KIAS will put you at over 230 KTAS


Steve Waite: Engineer at codelegend.com

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Thanks to all for the replies....I'm not sure any address my

above question which is either, how to adjust upward the

maximum spped of the aircraft , which I would think could

be done on the AIRCRAFT.CFG file, or, alternatively, how to

turn off on P3D2.2 the "overspeed" warning.....example of my

problem...I have a craft, kneeboard in reference section, says max

speed is 450 Knt, but the overrspeed warniong comes on at 350Knts

flying at 800 feet......any further thoughts apprecaited...if I am simply

not understaning your above repliesa s they relate to my issue,

then I'm at fault......JMH

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>> I have a craft, kneeboard in reference section, says max

speed is 450 Knt,

 

Is this value KTAS and does this value have an altitude specified?


Steve Waite: Engineer at codelegend.com

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How about you state what the aircraft is?


Ed Wilson

Mindstar Aviation
My Playland - I69

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Beech 350

 

[Reference Speeds]
cruise_speed            = 300.0                 //Knots True (KTAS)
max_indicated_speed     = 263                   //Red line (KIAS)

 

flying willy-nilly at 300knt will give your over-speed error :smile: 
 


Steve Waite: Engineer at codelegend.com

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Aircraft performance is generally stated in true airspeed, not indicated. Your need is to understand the difference between true and indicated, not altering the plane's config file. That's how all of the above replies relate to your issue.


Chris

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Agree with snglecoil,

 

You're probably seeing Indicated AirSpeed (IAS) in your cockpit while the performance charts tell you what to expect in True AirSpeed (TAS)

 

At 400 KIAS (knots IAS) you're really flying quite a bit faster through the air. If the aircraft cruise perf tables say 400 they mean Knots True AirSpeed (KTAS)... Indicated would be more like 260 KIAS at FL310

 

This would explain your overspeed warning.

 

What plane is it?


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Here's what I suspect...

 

Because they're trying to do 450kts at 800', and because the alarm comes on at 350kts at 800'... I'm going to guess the overspeed warning is built into the gauge code for the aircraft and not part of the aircraft.cfg at all.

 

That's my guess... now, is it the F22 or the F35? LOL


Ed Wilson

Mindstar Aviation
My Playland - I69

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