Ex52tech From United States of America, joined Dec 2006, 559 posts, RR: 1 Reply 1, posted (3 years 4 months 3 weeks 23 hours ago) and read 4249 times:
You can tell at a glance if something is a miss, especially with the engine instruments, they do save space, and to a lesser degree they even seem to be something of a fad that the industry went through.
"Saddest thing I ever witnessed....an airplane being scrapped"
Quoting Ex52tech (Reply 1): You can tell at a glance if something is a miss, especially with the engine instruments, they do save space,
Fully agree, you can see in a split second if someting is wrong with an engine parameter.
Because it saves space you can have more info in the FWD eye reference position, important during critical flight fases (starting,T/O and landing).
The only drawback was the low MTBF (4 dials in one instrument), so we always carried a few spares (expensive) in the TBO (technical board outfit), located in the belly (hold 4).
Ex52tech From United States of America, joined Dec 2006, 559 posts, RR: 1 Reply 7, posted (3 years 4 months 3 weeks 5 hours ago) and read 4022 times:
As far as who was first to use tapes, I know that the F-105 and the XB-70, just to name two, used tapes at least for ASI, and MACH readouts, but not for engine instrumentation.
Getting back to tapes for engine instrumentation, the tapes were easier to read engine operations such as tandem bleed closure on the JT9-7A,-7F,-7J than the later used EIDS flat screen readouts. EIDS was somewhat laggy and not as precise as the old "steam" tapes.
The only drawback, personally, with the tapes over the round gages with digital readouts was when performing a high power engine run-up. They could be difficult to read with any precision while bouncing around at high power with the brakes set. With EIDS we could take a snap shot and recall it when back at idle.
"Saddest thing I ever witnessed....an airplane being scrapped"
TF39 From United States of America, joined Jul 2006, 110 posts, RR: 0 Reply 8, posted (3 years 4 months 2 weeks 6 days 19 hours ago) and read 3916 times:
Quoting Ex52tech (Reply 7): As far as who was first to use tapes, I know that the F-105 and the XB-70, just to name two, used tapes at least for ASI, and MACH readouts, but not for engine instrumentation.
I'm wondering then if the C-141 was the first (or among the very first) to use the vertical tapes for engine instrumentation since it's first flight was in 1963? I couldn't find any pictures showing round gages in any of my books so I'm assuming it had them from the start.
Ex52tech From United States of America, joined Dec 2006, 559 posts, RR: 1 Reply 9, posted (3 years 4 months 2 weeks 6 days 16 hours ago) and read 3873 times:
Quoting TF39 (Reply 8): I'm wondering then if the C-141 was the first (or among the very first) to use the vertical tapes for engine instrumentation since it's first flight was in 1963? I couldn't find any pictures showing round gages in any of my books so I'm assuming it had them from the start.
That could very well be. I can't think of anything older that I have seen tapes for engine instruments.
"Saddest thing I ever witnessed....an airplane being scrapped"
PGNCS From United States of America, joined Apr 2007, 2516 posts, RR: 45 Reply 10, posted (3 years 4 months 2 weeks 5 days 22 hours ago) and read 3769 times:
Quoting Jetlagged (Reply 6): Round dials are much easier to read and give better rate indications.
I agree from a user's point of view. The tapes are in all ways inferior to round dials for engine indications. I have flown the L-1011 with tapes and round dials, and vastly prefer the round dials; a quick look at a column of instruments in a problem engine is much more intuitively revealing than looking through several rows of tightly-packed tapes. I have also flown the tape engine instruments on the 744, and found them to be my least favorite part of the glass in the aircraft.
I am a huge advocate of the PFD/ND format EFIS with tapes for primary flight instruments, however.
Quoting Ex52tech (Reply 7): As far as who was first to use tapes, I know that the F-105 and the XB-70, just to name two, used tapes at least for ASI, and MACH readouts, but not for engine instrumentation.
Interesting point, Ex52tech. B-model F-105's had round dials, but with F-105D and subsequent, the integrated flight instrument package with tapes was installed; there well may be something with earlier use of tapes in an application, but this is the first one I am personally familiar with. Of course the 105 had round dials for engine instruments...with only one engine it's not difficult to diagnose which one is having the problem!
Jetlagged From United Kingdom, joined Jan 2005, 2452 posts, RR: 17 Reply 11, posted (3 years 4 months 2 weeks 5 days 10 hours ago) and read 3697 times:
Quoting PGNCS (Reply 10): I am a huge advocate of the PFD/ND format EFIS with tapes for primary flight instruments, however.
Agree 100%. On a PFD the tapes usually have trend arrows added to help assess rate and are not tightly packed.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
Francoflier From France, joined Oct 2001, 3195 posts, RR: 10 Reply 12, posted (3 years 4 months 2 weeks 5 days 8 hours ago) and read 3676 times:
Quoting PGNCS (Reply 10): I have also flown the tape engine instruments on the 744, and found them to be my least favorite part of the glass in the aircraft.
I agree with that. Tape gauges, whether analog or digital, just don't give you the precise 'at a glance' indication of the value they're indicating. Trend monitoring is also a bit more difficult as there is no scale on the side of the gauge. They make it hard to accurately set your engines manually.
That being said, on modern aircrafts with FADEC, those indications aren't really important.
Looks like I picked the wrong week to quit posting...
747classic From Netherlands, joined Aug 2009, 1785 posts, RR: 11 Reply 13, posted (3 years 4 months 2 weeks 5 days 7 hours ago) and read 3661 times:
I have flown with pleasure for almost 30 years with the analoque vertical tape instruments on the 747's.
The thrust is roughly set with the N1 (GE) or EPR (P&W, RR) tapes, a little below the bugsetting (target N1 or EPR), calculated by the thrustsetting computer. Above the thust setting vertical tape parameter is always a numberical read out, to fine tune the thrust of the engines manually, if no FFRATS installed.
For very accurate monitoring of a limit exceeding or trending of the engines we always used the AIDS (aircraft integrated data system) as installed from our first 747 and made a print out.
Especially on a three or four engined aircraft you can IMO see the faulty engine or not normal engine parameter(s) much earlier (in a glance) than with the round dials.
On most digital engine displays you can choose between round or vertical annunciation (pin option).
Jetlagged From United Kingdom, joined Jan 2005, 2452 posts, RR: 17 Reply 14, posted (3 years 4 months 2 weeks 5 days 1 hour ago) and read 3593 times:
Quoting 747classic (Reply 13): Above the thust setting vertical tape parameter is always a numberical read out, to fine tune the thrust of the engines manually, if no FFRATS installed.
Even with FFRATS, you need to fine adjust the power setting as there is only one auto-throttle motor for all four engines (it sets the highest reading EPR/N1).
Quoting 747classic (Reply 13): The thrust is roughly set with the N1 (GE) or EPR (P&W, RR) tapes, a little below the bugsetting (target N1 or EPR), calculated by the thrustsetting computer.
With round dials you have a digital readout for each primary parameter (and a linear pointer scale). Tape scales are non-linear, which doesn't help quick reading.
Quoting 747classic (Reply 13): Especially on a three or four engined aircraft you can IMO see the faulty engine or not normal engine parameter(s) much earlier (in a glance) than with the round dials.
Just as quick and easy to scan all pointers parallel as all tapes lined up. Still, to each their own preference.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
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