Can't attain rated max speeds on aircraft

[KnifeEdge]

I downloaded like 3 different P-51Ds and Hs and I havn't been able to reach the rated max speeds with any of them.

The D that I'm using came from

Warwick Carter
E-mail:  au_mav@hotmail.com
Garry J. Smith
E-Mail:  garry@gjsmith.net
Web:     http://www.gjsmith.net

I know the 51D can reach 437mph at altitude and somewhere around 400 at sealevel both in level flight, but in FSX i've only been able to hit 300-350 mph in level flight at any altitude. This plane doesn't have an autopilot so it may be my bad piloting skills and my constant corrections slowing me down. I am using full throttle and 100% prop with auto mix fuel mixture, and changing any of these settings seems to either make no difference or slow me down.

With the H I had a little better luck as the one I downloaded did have an auto pilot and it got a little closer to its rated speed but still not much in excess of 400mph at any given altitude.

Strangely if I go to the map or flight review page in game the speed given there is consistently slower than the reading from the dash of the airplane, this doesn't seem to happen with any of the default planes from FSX so I was wondering if tihs was a coding error.

If anyone has been able to hit the 437mph at 26700ft with the P51D I'm using or has any tips for what I should do please do tell, I've been searching through forums and googling the hell outta this topic with no avail. Thanks in advance everyone.

[Fr. Bill]

I wish I had a dime for everytime someone asks about "slow speeds..."

As you gain altitude, the reported speed on the airspeed gauge will decrease...

You are confusing Indicated Airspeed (IAS) with actual True Airspeed (TAS).

TAS is the actual, real speed of the aircraft through the air...

GS (Ground Speed is the speed of the aircraft across the terrain, plus/minus any wind component.

Additionally, don't confuse the reporting units. Some airspeed indicators report miles-per-hour, others report knots-per-hour...

[KnifeEdge]

the thing is FSX lets you change IAS and TAS, and IAS should be the lowest figure of the two, likewise MPH is the measure which would give you the lowest numerical figure for any given velocity, knots or kph would give higher numbers

and GS would also be faster than air speed for the same reason (less dense air at altitude)

so the figure of 300-350 is low by any measure

[Fr. Bill]

and GS would also be faster than air speed for the same reason (less dense air at altitude)

Say what? Ground Speed has absolutely nothing to do with air density or altitude...

[Mobius]

It sounds like this post and some of the ones after it would be helpful:  http://www.simviation.com/cgi-bin/yabb2/YaBB.pl?num=1195085337/45#49