707-420 Engine Gauges Question

[GCarty]

What did the percentage-calibrated top-row engine gauges on the 707-420 measure? (The ones where the EPR gauges would be on other 707 marques). I could only find one image on airliners.net and the resolution's too low to read the gauges.

http://cdn-www.airliners.net/photos/pho ... 334564.jpg

This will hopefully make for updates for the next set of HJG panels for greater realism

[jonesey2k]

Available thrust like on the 1-11?

[TSR2]

Hi GCarty, and welcome.

I've edited your post as airliners.net does not allow direct linking to the images as it breaches copywright, so I've changed it to a clickable link. ;-)

[GCarty]

Available thrust like on the 1-11?

Is that outlet v. inlet pressure difference?

[GCarty]

I noticed in the photo that the gauges were reading about 30% even though the engines are clearly off (the N1 and N2 RPM gauges are indicating zero). I wonder if these gauges are EPR multiplied by a scaling factor (to make correct take-off power equal to 100%). Any more info?

[DanKH]

What about the suggested exhaust-temperature, as I mentioned over at HJG? Is that totally out of the question?

Btw. would that be of any interest at all? And if, why?

[clavel9]

It doesn't appear to be a thrust index gauge so if it's not an EPR gauge my best guess would be absolute exhaust gas pressure (P7).

[GCarty]

OK, P7 it is! I checked that airliners.net photo again, and the gauges indicated 29.9 with the engines shut down (which sounds very much like atmospheric pressure, in inches of mercury).