What is 'GPH'?

[gjereza]

In page 2-10 of the User Guide for the 310R Redux there is a paragraph that say that:

"For greatest PERFORMANCE...This should result in a fuel flow in the range of 15-18 GPH."

I'm guessing that this is 'gallons per hour'? But where do we get this information from in the 310R's instrument panel? I don't see it in any of the gauges.

[Raptor]

GPH = Gallons per hour.

Lower left on the Copilot panel you will see a gauge that reads "Fuel Flow LBS/HR" So you will have to make some conversions

1 lb per hour = 0.16 gall per hour

15 GPH = 1.5 lb / minute 1.5 X 60 = 90 lb/hour
18 GPH = 108 lb/hr which equals 75% cruise power on the gauge

[gjereza]

Thank you.

[gjereza]

@Raptor or anyone else, I have follow-up questions about the EDM 700 in the 310R:

Looking at the outer scale of the Fuel Flow Gauge:

1. Roughly what is the value of the GPH when a needle is on the 2.5 PSI mark? On the 21.7 mark?

2. The EDM display will lock on 'Peak EGT'. When does the value in the T column get unlocked? How? Can it lock/unlock multiple times in one flight?

3. For test and learning purposes, can the EDM be made to lock and unlock when the plane is on the ground by adjusting the throttle quadrant levers and with brakes on?

4. In the EDM manual, there is a reference to 'cruise MAP'. I did a search of the 310's User Guide but couldn't find information on it. What is 'cruise MAP'?

[azflyboy]

1:The highest fuel flow the gauge can register is 150lb/hr, which works out to 24 GPH per engine. The 21.7 PSI is the maximum the fuel system could put out, so it's somewhat higher than that. As for the idle PSI, I wasn't able to find an exact figure for that, but since Cessna assumes a burn of 4 gallons/25lbs total for start, taxi and takeoff, it's probably only a couple gallons per hour.

2: If I understood your question right, you can simply hit the "step" button after you found the peak EGT, and that unlocks the "T" column.

3: The EDM 700 functions on the ground, but requires the engines to be running.

4:"Cruise MAP" the cruise manifold pressure. You can find the charts for the cruise power settings on page 6-15/16 in the user guide.

It's worth mentioning that the default simulation of fuel/air mixture changes is fundamentally pretty broken in P3D, which it inherited from FSX. Compared to real aircraft, the mixture setting in P3D changes way too rapidly with altitude, so if setting the mixtures seems incredibly finicky, that's why.

[Raptor]

In addition, IIRC, the peak cylinder will always be #2 (FSX/P3D limitation) so, for all purposes you might look at that one only...

[gjereza]

1:The highest fuel flow the gauge can register is 150lb/hr, which works out to 24 GPH per engine. The 21.7 PSI is the maximum the fuel system could put out, so it's somewhat higher than that. As for the idle PSI, I wasn't able to find an exact figure for that, but since Cessna assumes a burn of 4 gallons/25lbs total for start, taxi and takeoff, it's probably only a couple gallons per hour.
...

1. In other words, to roughly calculate gph, divide pounds per hour (lb/hr) by six to get gallons per hour (gph). I got the figure six from your first sentence above (150/lb/hr divided by 24 GPH). Do I have that right?

2. And lock/unlock can be immediately repeated and done multiple times?

3. Yes, I meant the engine I'm checking is running.

4. On the chart at page 6-15/16, what is BHP?

Thank you.

[gjereza]

In addition, IIRC, the peak cylinder will always be #2 (FSX/P3D limitation) so, for all purposes you might look at that one only...

#2?

I thought it would always be #5 (page 2-10 in the User Guide).

[Raptor]

Well, I did say, If I Recall Correctly

Brake horsepower (BHP) is the amount of work generated by a motor under ideal conditions.

[N4GIX]

I thought it would always be #5 (page 2-10 in the User Guide).

The reason why I picked #5 is simply because that is the one cylinder in the C310R that gets the least amount of cooling airflow, so typically it is the hottest in real life as well.

[gjereza]

@Raptor and @N4GIX, thank you both.

Any comments on item #1 (estimating GPH value) and #2 (locking and checking peak EGT multiple times)?

[Raptor]

I'll say you are correct on #1. I'll let Bill comment on #2, although I though azflyboy had already touched on that

[gjereza]

I'll say you are correct on #1. I'll let Bill comment on #2, although I though azflyboy had already touched on that

With regards to #2, the reason I wanted clarification is because he said selecting the Step button unlocks the peak EGT value in the T column. I am confused with what he said because it cycles the temperature view to the 6 cylinders instead of unlocking the T column.

[gjereza]

Another question. Why does the EDM turn off by itself even though the engine was and still is running in idle at 1000 rpm?



How do I turn it back on without re-loading the scenario?

[N4GIX]

Another question. Why does the EDM turn off by itself even though the engine was and still is running in idle at 1000 rpm?

I've no idea at all. I have never had that happen to me...