Enhanced Performance

[thedispatcher]

Hi Dutch,

I'd like to see enhanced performance data used in the calculation of fuel burn and ETE - perhaps in a similar fashion to the text file format used by FSBuild. More specifically, I mean opening up the possibility of entering weight/altitude specific performance data for climb, cruise and descent for aircraft at the text file level so that ETE and fuel burn calculations can be more exact based on the given flight level, projected aircraft weight and cruise speed.

Using generic standard figures rarely yields fuel or time values close to actual, so I think this may be a good future enhancement. If you can come up with an entry format for this, I can prepare the performance tables for virtually every commercial aircraft in revenue service (and a few that aren't) for you as I have access to engineering performance data.

Regards,
Andrew

[Dutch Owen]

I'd love to have more accurate tables on which to base the estimates. If you could do the tables I'd be glad to change the calculations. We could start with one A/C until we have it right.

It would have to be an optional file attached to the aircraft characteristics, so that if people don't have the enhanced data it will revert to the generic.

Excellent idea!

Dutch

[thedispatcher]

Hi Dutch,

Good to hear! I have a sample profile created for the 737-800 - where would you like it sent?

[tvieno]

How about this, if FSCap would automatically adjust the airplane config files (Not the aircraft.cfg, but the ones FSCap uses) each time you land. That way it would give a more accurate fuel usage on climbs, cruises, and descents. Thus creating better fuel estimation.

[thedispatcher]

Performance is not that simple by a long shot ! Different flight level selection and gross weight drastically affect the fuel burn you'll encounter on a given flight, rendering one fixed climb/cruise/descent speed and hourly burn rate essentially useless. On a 737 sized aircraft, the fuel consumption can vary anywhere from 500 LBS to 1500 LBS over the course of an hour based on weight and altitude variables alone! That's not including differences induced by non-standard temperature which significantly affect the climb.

[tvieno]

True, but FSC's aircraft config uses just one number in it's estimation. Yeah, it adjusts the fuel usage when you enter in the winds.

What I was more referring to is when I set up the config. I had no idea what my fuel consumption was during climb or descent. I do have an idea where it is at cruise. So I threw in some bogus numbers in the fields. Something like 150% of cruise for climb and 66% for descent. With my suggestion, it would automatically tally how much fuel is consumed for climb, cruise, and descent. And over the long run, the numbers will average out to what is the mean.

[Aviator992]

Thats not the point tho, you should know atleast some sort of figure for what your aircraft is burning or you shouldn't be flying it... There are so many factors affecting fuel consumption, and even a "mean" figure wouldn't be accurate. It may be somewhat close, but not for what real pilots would use...

[thedispatcher]

Aug 22, 2010 22:12:54 GMT -5 tvieno said:

True, but FSC's aircraft config uses just one number in it's estimation.

... Hence the suggestion to expand the programs capacity to use more than one simple variable to derive fuel and time calculations! I don't think you understand that fuel burn and flight time vary considerably with even a 5,000 LBS difference in weight and a 5 degree change in temperature. Flying the same Portland to San Francisco flight back to back, with 5,000 LBS additional weight will shift the burn by 400 LBS, flight time by 3 or 4 minutes, and is enough to push you to an initial/final cruise altitude 2,000 FT lower than if you were 5,000 LBS lighter. Mean values are useless, they are not usable no matter how low your standards for accurate fuel burn/flight time prediction are. So you flew the last 10 flights at FL390/400, and record the "mean" average of that. Now you're stuck in the mid-teens flying Portland to Seattle due to traffic congestion. Even if you were in the mid 20's you'll still land a couple thou low because the overall burn is much higher at the low altitude - talking 3,600-3700 LBS per engine, per hour at 15,000 feet compared to 2,200 LBS per engine per hour at 40,000 feet. And that's looking at it in very primitive light, not even considering the time factor flying lower at a much slower airspeed. As the Aviator said, there are so many factors that affect fuel consumption that the only way to get a remotely close value is to use the correct data. Maybe you don't have any idea what your aircraft burns, or any aircraft should burn, but a number of us do, and have access to the data required to build a complete database for a large number of aircraft. And we're willing to provide that data to Dutch, if the program's capable of accepting that data. That's the whole point.

[tvieno]

Aug 23, 2010 4:00:52 GMT -5 thedispatcher said:

... Hence the suggestion to expand the programs capacity to use more than one simple variable to derive fuel and time calculations! I don't think you understand that fuel burn and flight time vary considerably with even a 5,000 LBS difference in weight and a 5 degree change in temperature. Flying the same Portland to San Francisco flight back to back, with 5,000 LBS additional weight will shift the burn by 400 LBS, flight time by 3 or 4 minutes, and is enough to push you to an initial/final cruise altitude 2,000 FT lower than if you were 5,000 LBS lighter. Mean values are useless, they are not usable no matter how low your standards for accurate fuel burn/flight time prediction are. So you flew the last 10 flights at FL390/400, and record the "mean" average of that. Now you're stuck in the mid-teens flying Portland to Seattle due to traffic congestion. Even if you were in the mid 20's you'll still land a couple thou low because the overall burn is much higher at the low altitude - talking 3,600-3700 LBS per engine, per hour at 15,000 feet compared to 2,200 LBS per engine per hour at 40,000 feet. And that's looking at it in very primitive light, not even considering the time factor flying lower at a much slower airspeed. As the Aviator said, there are so many factors that affect fuel consumption that the only way to get a remotely close value is to use the correct data. Maybe you don't have any idea what your aircraft burns, or any aircraft should burn, but a number of us do, and have access to the data required to build a complete database for a large number of aircraft. And we're willing to provide that data to Dutch, if the program's capable of accepting that data. That's the whole point.

True. I do understand about fuel consumption in relation to weight, speed, and winds; it is a part of my job, just not with aviation. But this is MSFS, things aren't as complicated as they are in real life. If it were, not everyone would be able to start the planes without hitting Ctrl+E. I was merely working with the data configuration at hand. Had Dutch considered various weights, speeds, and winds, he would added extra fields to take that into consideration. But it does show consideration on his part to have at least Climb, Cruise, Descent fields.

The 'enhancement' lies not with you or others who have a better understanding of fuel consumption. It is for the average virtual pilot who does not have a complete understanding of fuel consumption but shows interest in having the proper amount of fuel on hand.

I think you and I are on the same page in regards to having better fuel management, just differing ideas on what that should be. Yours being more extensive and mine being more simple.

Now if there was a way we could import our data into a database or spreadsheet, that would start to define the parameters. Various fields would be, a/c, FL, wgts, fuel climb, cruise, descent, cruise speeds, what else? How to capture that info and store it?

[Dutch Owen]

I'm very interested in this discussion. Keep in mind that we need to support a range of interests here - from the more casual sim pilot to those more dedicated. Simple is always best, but the real world isn't always simple!

Dutch