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I found this clip online that shows the speed tape on the Lockheed U-2 going what I perceive is the opposite direction to the 'normal' convention. On most aircraft, the higher values are above and so the tape scrolls downwards, but in this case it is mirrored.

Observe indicator on left for the first few seconds in the following clip:

Here's a photo as well from a french forum, actual source unknown:

pic

Why do this? On every aircraft I can think of it is the opposite.

Is it the fact that you pitch down, speed increases? Then you got the speed/altitude indicators moving in different directions, so I don't see how that would make it any more clear, especially when it appears it's the only aircraft doing this.

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  • $\begingroup$ Dunno about that... but I found it amusing that a plane the like the U2 appears to have a piece of yarn on the nose for coordinating turns. $\endgroup$ – abelenky Aug 7 '15 at 21:34
  • $\begingroup$ I would say it's intuitive because the tape moves upward if the speed increases. But then the ALT tape breaks that rule, so that can't be it. $\endgroup$ – JulianHzg Aug 8 '15 at 12:47
  • $\begingroup$ Just noticed the backup EADI's speedtape follows the same rule. $\endgroup$ – Marco Sanfilippo Aug 19 '15 at 12:58
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In essence, you are correct.
It was a conscious decision to do it that way: - when the nose pitches up, you're "pitching" toward the slower airspeed on the tape... - and you're pitching toward the higher altitude on the altitude tape.

My question: why do most aircraft have the higher speed near the top of the tape? Is it "just because the altitude tape does it that way"? Or is there a better reason.

Having flown the U-2 with the glass cockpit for over 10 years, it is intuitive and is "normal" for me to see that.

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  • 2
    $\begingroup$ Hello Jon, welcome to Aviation.SE! Follow up questions should be asked as a separate question, preferably with a reference to the original question, so they can attract their own answers. $\endgroup$ – DeltaLima Jan 14 '16 at 22:38
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This answer is a bit of a guess.

I think this design choice helps the pilot in manually flying in the coffin corner. By ensuring that the direction of movement of the horizon, altitude and speed tape all require the same stick input, less mental workload is needed to fly the aircraft.

If the nose of the aircraft is lowered:

  1. The artificial horizon will move up
  2. The altitude will decrease, hence the altitude tape moves up
  3. The speed will increase, hence the speed tape moves up

Any visual clue from the display that involves an upward optical flow can be corrected by pulling the stick. This consistent behaviour reduces the mental workload.

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  • $\begingroup$ Or maybe it was intentionally confusing so they'd pay attention :D $\endgroup$ – ymb1 Sep 9 '16 at 19:29

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