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glenaw

Speed Tape Minimum Speed Indication and Taxi Speed PMDG 737 NGX

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Hello Everyone,

 

I have a question with speed tape indications.

 

I use to fly X-Plane EADT 737 Project.

 

The plane was ok but just didn't quite  go far enough.

 

Here is a difference I notice on speed tape

 

X-Plane, EADT 737 Projcect, speed tape went to zero.

 

PMDG goes to 40, not below!

 

Now taxi speed is, correct me if I'm wrong, under 20 mph

 

How do I tell in the PMDG if I'm going over speed while taxing??

 

I really enjoy the PMDG and the fact that everything is so precise. I think we all enjoy doing a sim as accurate as possible.

 

Any help in this matter would be greatly appreciated.

 

Glen Woodman

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I have not flown the NG, but I flown the Lear 45, CL300, and DA2000.  The speed tapes in these aircraft read only down to 40 knots.  The airspeed indicators are pitot pressure driven and likely not reliable below that speed.

 

Taxi speed is usually determined using the IRU/GPS displayed ground speed readout on the Navigation Display.  Straight-taxi speeds are generally limited to between 20 to 30 knots ground speed. Turns should be conducted between 8-12 knots (depending on the source your reading) to prevent tire side loading.   Taxi speeds above 35 knots can generate excessive tire temperatures, which is not good if you need to abort the takeoff.

 

Best regards,

 

Rich Boll

Wichita KS

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X-Plane, EADT 737 Projcect, speed tape went to zero.

 

This would be an incorrect modeling of the 737, then.

 

 

 


PMDG goes to 40, not below!

 

Correct. Remember that airspeed is, well, the speed through the air. In order to determine speed against static air, the air needs to be rammed into the pitot tube. There isn't much ramming being done below 40, so the airspeed would be inaccurate, and is not displayed.

 

 

 


How do I tell in the PMDG if I'm going over speed while taxing??

 

As mentioned by Joseph, you're looking for groundspeed, which is displayed at the bottom of the speed tape (with "GS" next to the number), or on the ND (the next screen over - also with "GS" next to it).

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Thanks Everyone for the reply's.  I did notice before I came back to the forum the the ground speed indicator reads below the speed tape.  Learning curve for me! Sorry I didn't notice this before writing the inquiry. 

 

Even with knowing that before I came back I did learn a few new things from all the reply's.

 

Thanks for the reply's.

 

Glen Woodman

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Just a note that the GS display below the speed tape is an OPTION. So you may find some NGX panel configurations that have that option turned off.

 

Dave

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