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38 votes
Accepted

What aircraft is this compass from?

The US Army Air Force and Navy compass type D-12 encompasses several models manufactured by Bendix/Pioneer: 1801, 1826 (yours), 1832 and 1833. The D-12: Is a direct reading compass, not a fluxgate. ...
mins's user avatar
  • 75k
24 votes
Accepted

What does the small needle + scale on this turboprop's N1 gauges indicate?

It duplicates the percent graduations in the large dial but at a finer resolution, with one percent increments. It's just to make the individual percent graduations easier to discern at a glance ...
John K's user avatar
  • 132k
23 votes
Accepted

How accurate must fuel gauges be for VFR flight?

The indicator must be calibrated to read zero when that tank is actually empty of all usable fuel (in level flight). Bouncing is fine as long as they do not bounce when the tank is actually empty. ...
acpilot's user avatar
  • 6,016
16 votes
Accepted

Why not have Pitot Heat always on?

I can generally only speak for commercial aviation. The reasoning is probably the same or similar for General Aviation, but seeing as that is such a wide and varied field, with a tremendous number of ...
Frank's user avatar
  • 2,403
16 votes
Accepted

What kind of gauge is this?

This is likely a suction gauge. Specifically, this gauge must read between certain values to assure the pilot that flight instruments operated by an engine-driven suction pump are operating correctly. ...
Thomas Perry's user avatar
  • 1,392
15 votes

What does the small needle + scale on this turboprop's N1 gauges indicate?

If the engine is at 95% RPM, the large needle will point halfway between the "90" and the "100" indication on the outer scale, and the needle on the small dial will point to the &...
Ralph J's user avatar
  • 51.8k
11 votes

How accurate must fuel gauges be for VFR flight?

The only legal requirement of fuel gauges on normal and transport category airplanes is that they read empty when the fuel tanks are empty (how convenient!). In general, for normal category aircraft, ...
Romeo_4808N's user avatar
  • 74.1k
10 votes
Accepted

Where does the altimeter measure from?

There are a few types of altimeters but they all generally do the same thing and can be calibrated to anything if need be. Where they measure from and what they consider 0 are really 2 different ...
Dave's user avatar
  • 101k
7 votes
Accepted

WWII fuel gauge: single needle and dual range

That looks like an animated cockpit, and if i was a betting man Id say that someone googled "german airplane gauges" and didn't know what they are looking at. The labeling on the spectrum is ...
Dave's user avatar
  • 101k
6 votes
Accepted

Why is this Cessna flap position indicator marked so irregularly?

Because it was the analog world and no other (easy) solutions exist. Providing an exhaustive answer will require too much space here, but I'll give the idea with the help of some figures. So, this is ...
ocirocir's user avatar
  • 1,972
6 votes

Why not have Pitot Heat always on?

Depends on the airframe and where it is operating. For light aircraft operating a low altitudes (<10,000 ft) pitot heat use is going to be dependent upon whether the pilot anticipates encountering ...
Romeo_4808N's user avatar
  • 74.1k
6 votes

Where does the altimeter measure from?

The altitude callout is usually given using the radio altimeter. The radio altimeter (Tx/Rx) is usually located in the forward fuselage and calibrated to tell the altitude of the main landing gear ...
aeroalias's user avatar
  • 100k
5 votes
Accepted

What are these engine gauges in the Comet 4 for?

They were used on takeoff to monitor engine performance. Takeoff power should result in the needles moving to the vertical marker and all engines should be registering the same reading. The ...
Juan Jimenez's user avatar
5 votes
Accepted

What aircraft is this clock from?

Here's an excerpt from page 13 of the manufacturer's 1966 catalog for a very similar clock, model 651-12-24. It might have been installed in many aircraft. Logos on page 14 include American Air ...
Camille Goudeseune's user avatar
5 votes
Accepted

Why does the X-3 have two oil pressure gauges per engine?

After some research, Ralph's comment is almost certainly the answer here: during the restoration they installed incorrect (though period-accurate) oil pressure gauges, rather than fuel pressure gauges....
egid's user avatar
  • 23.3k
4 votes

Early "digital" rotating digit wheel type gauges

It depended on the indicator and what it was trying to measure. The encoding altimeters on some earlier Boeing jets had a similar style readout that had the two rightmost digits linked and displayed ...
Dave's user avatar
  • 101k
3 votes

Why not have Pitot Heat always on?

All good responses. Actual temps of heated probes can be as high as 1200F per our in house tests. Air data sensors (TAT, ICE, AOA, etc.) all require protective covers at some point for a variety of ...
Sam Jarvis Jr.'s user avatar
3 votes

What kind of gauge is this?

This is a Vacuum Pressure gauge that would have been used to indicate the system vacuum pressure in an airplane.
Dave's user avatar
  • 101k
2 votes

Are steam gauges more reliable than glass panels?

Most aircraft using electronic displays have double (and sometimes triple) redundant power supplies to keep the electronics alive in cases of power failure. The mechanical gauge panels of the not so ...
Geoff's user avatar
  • 1,443
2 votes

Why not have Pitot Heat always on?

If you heat the pitot tube while in flight, it will keep a reasonable temperature. If you heat it when you are on the ground at a normal temperature and without any forced convection, it will reach a ...
Gianni Alessandro's user avatar
1 vote

Are steam gauges more reliable than glass panels?

Most integrated flight displays – the so-called glass cockpit – contain multiple redundancies both on the forms of computer power, and electrical power sources to keep them operating in the event of ...
Romeo_4808N's user avatar
  • 74.1k

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