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707-420 Engine Gauges Question
Posted: 18 Mar 2008, 19:03
by 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

Re: 707-420 Engine Gauges Question
Posted: 18 Mar 2008, 19:22
by jonesey2k
Available thrust like on the 1-11?
Re: 707-420 Engine Gauges Question
Posted: 18 Mar 2008, 19:46
by 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. ;-)
Re: 707-420 Engine Gauges Question
Posted: 18 Mar 2008, 22:26
by GCarty
jonesey2k wrote:Available thrust like on the 1-11?
Is that outlet v. inlet pressure difference?
Re: 707-420 Engine Gauges Question
Posted: 19 Mar 2008, 11:39
by 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?
Re: 707-420 Engine Gauges Question
Posted: 19 Mar 2008, 12:11
by 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?
Re: 707-420 Engine Gauges Question
Posted: 19 Mar 2008, 14:49
by 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).
Re: 707-420 Engine Gauges Question
Posted: 10 May 2008, 10:42
by 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).