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No this was common - we discussed this in another thread. The Gauge is showing "indicated air speed," you have to calculate for "true air speed"
From a P-38
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I believe the OP is asking about that one specific gauge, its increments of 50mph and its use in an aircraft, ....., 200, 250, 300, 350, 400, 450, 500. It's not typical for a WWII ASI.
P-38 gauge, ....., 200, 250, 300, 400, 500, 600, 700.
Is this the only pic you have of this? Where did the pic come from?Were any American aircraft in WW2 fitted with airspeed indicators topping out at 500 mph (or maybe knots), scaled in units of 50, and arranged with the needle's "zero" position like this? I can't quite find a match anywhere.
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Since there are two, possibly something to do with the engines, RPM or whatever.Sorry all, I've been tied up doing unexpected "springtime" repairs on the lawn mower and car. The pictured gauge is one of 2 identical ones sitting side by side on the upper panel of the McDonnell XP-67 aircraft. Both of these gauges were replaced at some point with ones that only went up to 300 instead of 500, which seems to rule them out as airspeed indicators for an aircraft that was required to make 400+. Could the pictured gauge, going from 0 in increments of 50 units, be something else? Or can someone say definitely that it's an airspeed gauge? There's no such gauge anywhere on the main panel, though, so it seems like that's what it has to be...but why 2 of them, side by side? I would think the last thing a pilot would want is a disagreement between gauges about how fast he's going. It's a puzzle and it's making my head hurt...
Sorry all, I've been tied up doing unexpected "springtime" repairs on the lawn mower and car. The pictured gauge is one of 2 identical ones sitting side by side on the upper panel of the McDonnell XP-67 aircraft. Both of these gauges were replaced at some point with ones that only went up to 300 instead of 500, which seems to rule them out as airspeed indicators for an aircraft that was required to make 400+. Could the pictured gauge, going from 0 in increments of 50 units, be something else? Or can someone say definitely that it's an airspeed gauge? There's no such gauge anywhere on the main panel, though, so it seems like that's what it has to be...but why 2 of them, side by side? I would think the last thing a pilot would want is a disagreement between gauges about how fast he's going. It's a puzzle and it's making my head hurt...
The RPM gauges are down on the main panel, we have a crisp photo of them. I'm still thinking airspeed but I wish I could find a photo of another one like these, with 0 at the lower left and 500 at the lower right, and increments of 50 all the way around.Since there are two, possibly something to do with the engines, RPM or whatever.
That's what I've been thinking too. Can't help wondering why they thought they'd get 2 different results from LH and RH probes, but they must have had a reason.It seems in this picture there are 2 pitot tubes, on on each wing. Again, maybe for flight testing purposes?
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During the testing process, they would look for irregularities (i.e.: working out the bugs), so extensive and detailed instruments would provide such data.That's what I've been thinking too. Can't help wondering why they thought they'd get 2 different results from LH and RH probes, but they must have had a reason.
Manifold Pressure, left and right? What a poorly laid out instrument panel! Accident looking for a place to happen. Designed for manufacturer's convenience, not aircrew safety. Maybe they just didn't have a two needle MAP gauge handy when they were hooking up this "test" panel. Can't believe they would go into production with a hodge podge panel like that.
No pics in your linkIt was the XP-67, not production. The upper (temporary) instrument panel was for Flight Test. The typical two needle gauges are in the lower panel.
Orange Logic - McDonnell XP-67 Bat Cockpit
If you've ever done multi engine training, you'd probably have an idea. A plane with a single pitot tube static port system usually has significant airspeed errors, since single engine flight, especially down near VMC (where it's most critical) is an almost continuous sideslip. If you have two pitot tubes with correspondingly located static ports, and mounted at slightly converging angles, all feeding a single set of ALT, ASI, and VSI, the errors will tend to cancel or average, giving you a "poor man's Air Data Computer".Can't help wondering why they thought they'd get 2 different results from LH and RH probes, but they must have had a reason.