w.i.p FUEL CONSUMPTION IN ME FLIGHT PLANNING

[Hulkbust44]

Until we get the -210 we won't know for sure, but those numbers sound just fine, the -402 should be more efficient.

[captain_dalan]

2 hours ago, Hulkbust44 said:

Until we get the -210 we won't know for sure, but those numbers sound just fine, the -402 should be more efficient.

Of course, the 400 should burn 6.3% more fuel for every pound of thrust in full AB then the 402. The 402 however produces more thrust. About 11% more (10.6 to be more precise). And that's just static thrust, without taking the effects of the ram air as we accelerate. 
So if we take SFC and static thrust only we get:
16000lbs * 1.85lbs/(lbs*h) = 29600lbs/h for the 400 and
17700lbs * 1.74lbs/(lbs*h) = 30798lbs/h for the 402
That means, even without the extra airflow and extra thrust produced, at full AB the 402 should burn about 4% more then the 400.
The data in the manual states the 400 at mach one, full AB burns 1320lbs/min for both engines. The 402 should burn at least 4% more at full AB (and as we are going even faster, probably a bit extra on top of that), or 1373lbs/min for both engines. But what we get in DCS is 1155.7lbs/min or 84.15% of the expected value. That's a 15% difference at least. And probably more.

[Fortinero]

I was about to do the same post but now, in 2023, in short, was there any change in these years?

Basically, doing tests nowadays, taking into account that the F/A-18C Lote20 that is modeled in DCS uses the F404-GE-402, about which there is a lot of public information circulating around, so I am not going to put much data, only a a rough calculation I did with all that info, just say that this engine in burner, it consumes 10% less than the F110-GE-129 and weighs 70% less too, even so, in the game, the Hornet with two engines in burners burns 12% less than the Viper with one engine.

My common sense tells me that the Hornet should burn almost twice as much as the Viper...

[DukeAngus]

as the story goes, send them the unclassified and for public release  documents with the numbers. cuz numbers of wiki dont cut it.

 

without knowing the numbers, growing up i always heard the f/a18 called a whisper jet and trashed talked about its Eco-saver engines.

Edited February 5, 2023 by DukeAngus

[captain_dalan]

13 hours ago, DukeAngus said:

as the story goes, send them the unclassified and for public release  documents with the numbers. cuz numbers of wiki dont cut it.

 

without knowing the numbers, growing up i always heard the f/a18 called a whisper jet and trashed talked about its Eco-saver engines.

 

I did just that above...

[MarkyMark]

On 5/1/2020 at 9:45 AM, Airhunter said:

I recently did some comparisons between various aircraft in DCS as some people have stated that the efficiency of the JF-17 and the Hornet are quite high. To my surprise I found a very head-scratching engine economy and performance on the Hornet. All tests were at 30000ft, ISA-like conditions, full internal fuel and the default DCS loadout (pylons when applicable). The Hornet was the outlier across the board and did not even closely match the publically available and stated values I have found. It has by far the longest full AB time of all jets I have tested in DCS, much better economy and a much lower TSFC than most other comparable jets in DCS. Below are my test results.

 

 

 

 

 

Especially in the chart above you can see the F110-GE-400/402's TSFC of 1,23 in FULL! afterburner. Publically available sources state a value of 1,74, which is mostly in line with comparable engines of similar thrust rating and size.

 

 

Below is another picture showing a fuel flow of 22200 lbs/h in full AB at Mach 1.63 and 30000ft. I think GE would've won a nobel prize by now if they managed to develop such an efficient engine.

 

 

Now, other aircraft such as the F-14B, and F-16C match the stated values very well, the 16C's fuel flow matches the real, publically available FF charts mostly within a margin of +/- 5%. I wasn't able to find any publically available fuel flow charts for our F/A-18C and I do know the document designation of where to find those values, however this very document seems to be classified. Now my question to ED - since your aircraft are built on publically available data, what source or data did you guys use to model this? Could you please reference a source that would back the current performance of the Hornet's engines? If not, would you please consider adjusting these values based on public TSFC values for dry and wet thrust? Currently the Hornet is way more efficient than the Tomcat or any other comparable jet- nothing of the "short legs" the US NAVY was talking about all these past years.

No wonder the F16s I fly with are always carrying lots of luggage, didn’t know the internal fuel was 3000lbs less than the hornet. 

[maxsin72]

I have also seen that F18 overperforms really a lot at sea level with 0°C (many servers are in winter configuration during this months), 0 wind, QNH 759-29.92: it's mach 1.32 (read on the HUD, tacview see mach 1.28) capable in levelled flight full AB, simply impossible in real life with that wings.

Please see tacview file attached

Tacview-20230219-001406-DCS-mobettametas_Dogfight_Arena_v1.71.2.zip.acmi

Edited February 18, 2023 by maxsin72

[Hazardpro]

On 2/1/2023 at 5:18 PM, Fortinero said:

I was about to do the same post but now, in 2023, in short, was there any change in these years?

Basically, doing tests nowadays, taking into account that the F/A-18C Lote20 that is modeled in DCS uses the F404-GE-402, about which there is a lot of public information circulating around, so I am not going to put much data, only a a rough calculation I did with all that info, just say that this engine in burner, it consumes 10% less than the F110-GE-129 and weighs 70% less too, even so, in the game, the Hornet with two engines in burners burns 12% less than the Viper with one engine.

My common sense tells me that the Hornet should burn almost twice as much as the Viper...

The F404 has ~10% better TSFC than the F110 at full burner so 12% less consumption makes sense. Not sure where you are getting the 2x from...

[Fortinero]

1 hour ago, Hazardpro said:

The F404 has ~10% better TSFC than the F110 at full burner so 12% less consumption makes sense. Not sure where you are getting the 2x from...

Cuz the Hornet has two engines...

[Hazardpro]

37 minutes ago, Fortinero said:

Cuz the Hornet has two engines...

They are not the same sized engines. The F404 is much smaller than the F110.

[Fortinero]

20 hours ago, Hazardpro said:

They are not the same sized engines. The F404 is much smaller than the F110.

Dude, the F110-GE-129 weights 770kg more than the F404, and both F404 with burners still consumes 12% less than a single F110... the user captain_dalan exposed great info about this behavior already.

[Hazardpro]

2 hours ago, Fortinero said:

Dude, the F110-GE-129 weights 770kg more than the F404, and both F404 with burners still consumes 12% less than a single F110... the user captain_dalan exposed great info about this behavior already.

Yes, comparing the TSFC and rated thrust for these engines the F404 in DCS is performing maybe 10-20% better than expected over the F110. It's been done 2 or 3 times in this thread already. Not 200% like you were saying, that's just ridiculous. We compare engine fuel consumption by thrust, not weight.

 

The publicly available numbers I've seen have the F404 (at full burner) with ~10% better TSFC than the F110 and produce ~20% more thrust (2x engines), so you would expect maybe 10% greater consumption for the F-18, not 200%. 

Edited February 21, 2023 by Hazardpro

[Fortinero]

1 hour ago, Hazardpro said:

Yes, comparing the TSFC and rated thrust for these engines the F404 in DCS is performing maybe 10-20% better than expected over the F110. It's been done 2 or 3 times in this thread already. Not 200% like you were saying, that's just ridiculous. We compare engine fuel consumption by thrust, not weight.

 

The publicly available numbers I've seen have the F404 (at full burner) with ~10% better TSFC than the F110 and produce ~20% more thrust (2x engines), so you would expect maybe 10% greater consumption for the F-18, not 200%. 

 

Where I said that the Hornet have "200% greater fuel consumption"? 

 

I will write it again: in DCS, the F-18, burns less fuel in afterburner, than the F-16.

 

Yes, the F404 is more efficient engine, is smaller (770kg less than F110, I answered what you referenced about size), but not 50% more efficient, so, why two of them, in afterburner, burns less fuel per minute (almost 12%) than one single F110 in afterburner in DCS?

[Hazardpro]

8 hours ago, Fortinero said:

Where I said that the Hornet have "200% greater fuel consumption"? 

 

I will write it again: in DCS, the F-18, burns less fuel in afterburner, than the F-16.

 

Yes, the F404 is more efficient engine, is smaller (770kg less than F110, I answered what you referenced about size), but not 50% more efficient, so, why two of them, in afterburner, burns less fuel per minute (almost 12%) than one single F110 in afterburner in DCS?

I literally walked through the math in my post, they should have about the same fuel burn, maybe 10% more for the Hornet. The fact the Hornet has 2 engines has nothing to do with it.

[Fortinero]

10 hours ago, Hazardpro said:

I literally walked through the math in my post, they should have about the same fuel burn, maybe 10% more for the Hornet. The fact the Hornet has 2 engines has nothing to do with it.

All good, but right now is not even "10% more", is at least a 12% less, so, seems wrong having in mind all what everyone posted about this topic, one could think than the Hornet in DCS should be burning around a 22% more fuel in afterburner than the how it does now.

 

The current state, you can fast check it in game, take a Viper and a Hornet with same fuel, lets say 3000lbs each and burn at the same altitude for on minute and watch what's left in each one main tanks, just for having an aproximation.

[Hazardpro]

8 hours ago, Fortinero said:

All good, but right now is not even "10% more", is at least a 12% less, so, seems wrong having in mind all what everyone posted about this topic, one could think than the Hornet in DCS should be burning around a 22% more fuel in afterburner than the how it does now.

 

The current state, you can fast check it in game, take a Viper and a Hornet with same fuel, lets say 3000lbs each and burn at the same altitude for on minute and watch what's left in each one main tanks, just for having an aproximation.

Yes I agree the performance in DCS does seem to be a bit off. Though also keep in mind if we're comparing the published performance numbers of both engines they are going to be most likely figures for static testing at calibrated STP sea level. So if you are testing those ratios in game you should be sitting on the ground with the wheels chocked or you are introducing more variables.

[captain_dalan]

On 2/23/2023 at 1:43 AM, Hazardpro said:

Yes I agree the performance in DCS does seem to be a bit off. Though also keep in mind if we're comparing the published performance numbers of both engines they are going to be most likely figures for static testing at calibrated STP sea level. So if you are testing those ratios in game you should be sitting on the ground with the wheels chocked or you are introducing more variables.

Note that installed thrust most of the time differs from specified thrust for various reason (inlet geometry, bleed air, engine tuning), but still.... i liked this idea, so i gave it a go tonight. Here's the video, but if people are bored of watching 9 and half minutes of contributing to the greenhouse gas emissions (which i can't blame them for), the end result is there is about 9 and a half percent difference between SFC stated in open sources and burning static in DCS ( 937.9lbs/minute VS 1026.6lbs/minute). As usual, the values in DCS are lower. But i would take this finding with less assuredness .... (is that even a word) then values extracted from flight manuals.  Also, the full numbers and calcs are in the description.
 

 

[timothyboss]

On 5/23/2021 at 2:54 PM, nazradu said:

That's at least something to start with! THX. Now I need to figure out a factor for the influence of loadout. I guess in the end I will only get close to the perfect solution, as things can change rapidly with circumstances, but getting close as possible is fine for me.

Take a look at my sheet.  It can be located from my site.  Take a copy.  Take the data.  The data sheets are hidden, just unhide.  All weights/drags/ factors are included.  Take what you need.  

https://sites.google.com/view/fa-18c-flight-planner/home

I have interpolated the values in the 'MACH AND FUEL DATA' sheet.  This is raw data from many flights in the hornet at different weights, drag indexes, altitude, temperatures (did not effect) and winds(very little effect). The values did required some factoring as the fuel page did not accurately display the LB/NM with accuracy.  Also note when fuel planning that in-game temperature changes in mission editor changes the weight of the fuel of the aircraft in reverse from real world meaning: The F18 has a fixed volume fuel capacity.  Colder fuel is more dense than warm fuel.  Colder temps should have a higher weight displayed in jet but does not.  Its backwards in DCS, for now, so keep that in mind when fuel planning.  Hopefully ED will acknowledge it. 

Edited March 12, 2023 by timothyboss

[timothyboss]

I took many flights to record and understand the fuel burn rate in the Hornet for mission planning and I noticed 2 things. 

FIRST:

The Hornet 'FPAS Page' LB/NM is not accurate with actual fuel burned: 

To validate: Make a standard mission in editor with 15C air temp AGL 15 air start for ease. low drag loadout (centerline only) and 50% fuel capacity.

Get airborne, straight and level flying FPAS recommended. Record fuel at start of flight, fly FPAS for 50NM record fuel at end of flight.  Also take note of the LB/NM,  you will need this.

Calculation 1:: Total fuel at start of 50nm flight minus remaining = total fuel burned. 

Calculation 2: 50NM * LB/NM (FPAS Page)= total fuel burned.  

Calculation 1 will not be the same as calculation 2.  The actual burn rate is on average 2-4 lbs/NM more than what is displayed on FPAS.

SECOND:

Fuel weight changes based on temperature, but backwards:

To Validate: Make a mission with a Hornet on ground, centerline, max fuel to remove variables keep volume constant. (Density of fuel at -12.4C = 6.94 / 0C = 6.74 / 40C = 6.09)

Set mission editor temperature to 15C and result is weight of fuel in hornet is 13,047lbs in DCS.  This is close to 6.74 * 1919 gal = 12,934 lbs.

Set mission editor temperature to max (40C) and result is weight of fuel in Hornet is higher than 13,047 lbs.  But Real World is 6.09 * 1919 = 11,686 lbs.  Why is the hornet more when it should be less.

Set mission editor temperature to min (-12.4C) and result is weight of fuel in Hornet is lower than 13,047 lbs.  But Real World is 6.94 * 1919 = 13,317 lbs.  Why is the Hornet Less when it should be more.

The Hornets fuel poundage is changing with respect to volume changes when it should change with respect to density changes.  The volume is constant!  The only variable is temperature which we can control.

Hopefully one day ED will acknowledge.....

[timothyboss]

On 1/16/2023 at 6:42 AM, CHUCK2069 said:

Hello

 

Would it be Possible to have an estimation of the Fuel Burn during the navigation branches from wpt X to wpt Y 

It would be more realistic to Know exactly how much fuel will be needed

 

Thanks

Milan

Check out something I have created for this exact issue. (link below) There is nothing out there for good fuel planning so I made something over the last couple years.  Make a copy of your own and use it for fuel planning.  It is always a work in progress to continuously improve from users input, but I recently overhauled the fuel consumption by taking an ungodly amount of flights at different weights, drag indexes and altitudes.  I did notice that the LB/NM on the FPAS page is not accurate (about 2-4 lb/nm low on average) and that the fuels weight changes with temperature (which is nice) but is backwards.  On a cold day the fuel should weigh more, not less.  see for yourself sometime.

https://sites.google.com/view/fa-18c-flight-planner/home

[ZaHaDum]

Recently I was also interested in how much fuel airplanes consume. Used the same testing method as you did @captain_dalan Conditions - 1000 ft MSL, t=20 С, no payload and pylons.
Results:
- MiG-29 burns = 1920 lbs/min
- Mirage 2000С burns = 1000 lbs/min
- F-15 burns = 2260 lbs/min
- F/A-18 burns - 1150 lbs/min
- Su-27 burns = 2400 lbs/min
- F-16 burns = 1432 lbs/min

Edited May 11, 2023 by ZaHaDum

[ZaHaDum]

One more experiment - comparison of thrust to weight ratio. All aircrafts have fuel for 5min MaxAB, no payload and no pylons. Engine thrust is taken from official site for each one. Fuel consumption used according to previous message.
Results:
1,43 — F-15
1,22 — Mig-29
1,14 — F/A-18
1,09 — Su-27
1,07 — F-16

[IanC58]

54 minutes ago, ZaHaDum said:

One more experiment - comparison of thrust to weight ratio. All aircrafts have fuel for 5min MaxAB, no payload and no pylons. Engine thrust is taken from official site for each one. Fuel consumption used according to previous message.
Results:
1,43 — F-15
1,22 — Mig-29
1,14 — F/A-18
1,09 — Su-27
1,07 — F-16

I fail to see how this is useful for mission planning, no payload, no pylons, 1000ft, max ab?

Edited May 11, 2023 by IanC58
more info

[ZaHaDum]

On 5/11/2023 at 9:11 PM, IanC58 said:

I fail to see how this is useful for mission planning, no payload, no pylons, 1000ft, max ab?

 

there was no goal to achive some extra use in mission. Only for fun and curiosity

[IanC58]

2 hours ago, ZaHaDum said:

there was no goal to achive some extra use in mission. Only for fun and curiosity

I must have not understood the forum post title then