Combat and navigation fuel consumption

[JEFX]

Hi everybody!

 

I have been fiddling around with fuel management recently and I want to share my experiments. This is going to be a long post, excuse me. I really did those experiments quite scientifically and they should reflect the way things are IN THIS GAME and not in real life...

 

It would be great to hear reactions from the DEVS, just to make shure I got things right.

 

It would be great also to hear reactions from real life pilots, just to compare and to fine tune the procedures...

 

 

JEFX

 

 

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SU-33 FUEL MANAGEMENT

(NAVIGATION AND COMBAT)

 

 

Fuel consumption and management under the various flight and combat modes is rather under-documented in Lockon. I made a lot of experiments and here are my observations and conclusions. This is not real world data but rather data derived from what the devs of our simulation have programmed in the game (version 1.12a).

 

In the following text, distances are in km, altitude in meters, speed either in IAS (indicated air speed, as seen on the HUD, which varies with altitude) and TAS (true air speed, or ground speed, essential for navigation purposes and wind in m/s. Wind effect, which should be taken into account, is described at the end.

 

All experiments where done with an SU-33 with around 4000 kg of fuel (42% of max fuel load) since a full aircraft is much less manoeuverable in combat.

 

It is also worth taking into account that given our relatively small theatre, flying around carrying 9000 kg of fuel is irrelevant for a normal mission. As an example derived from what I will expose lower, that much fuel would be enough for a fully loaded AA combat flanker (10 missiles and ECM pods) to perform the following : an afterburner take-off, a full military power (100% RPM) climb to cruise altitude of 9000m , travel a distance of 200 km to CAP (combat air patrol) station area, patrol at 900 km/h (TAS) for one hour, (therefore covering 900 km of territory), cruise 200 km back to base, descend to the IAF and make a long approach, land, and that still gives you a good 5 minutes of full combat after-burner fuel…

 

That is a too long mission…(especially given the fact that the modelled area of land in our map from the westernmost tip of Crimea to the last mountain in the south-east Caucasus is only diagonally about 900 km wide…).

 

Since this will not be the typical Lockon mission, I thought that giving ourselves a well calculated limited amount of fuel is not only in accordance with real life flying but is also fun and challenging. (One of those rare things we can program to make our life more real in the lockon world).

 

I have studied 4 different altitude profiles : 100 m (sea level, or NOE, nap of the earth), 2000 m (ground attack, terrain hiding possible altitude), 6000 m and 9000 m (cruising altitudes). Together, they give a good portrait of the fuel consumption variables.

 

I have experimented with 2 easy airspeeds : 600 km/h and 900 km/h (TAS). At 600 km/h TAS, (a relatively slow speed for a fighter), your AC travels 10 km in one minute and at 900 TAS, (a very normal speed for the flanker), your AC travels 15 km in one minute, handy for mental navigation. At higher altitude than 10000m, it is almost impossible to maintain a higher speed without going into afterburner. This is why I thought that 900 km/h of ground speed (TAS) at 9000m altitude was a good cruising compromise to still save fuel, (since, theoretically, the higher you go, the less fuel it takes).

 

I have results for three configurations : clean (only 40% Fuel, no weapons), full AA load (2xR-73, 2xR-27R, 6xR-27ER, ECM pods, 40% Fuel) and a very heavy full AG load (6xFAB-500 bombs, 2xR-73 and 2xR27R, ECM pods, 40% fuel).

 

Here are the results of my observations (Fuel consumption is in kg of fuel/100 km of ground travel).

 

 

CRUISING FUEL CONSUMPTION

 

CONDITIONS FUEL CONSUMPTION (kg/100km)

 

ALT TAS (IAS) CLEAN FULL AA FULL AG

 

9000m 900 km/h (550) 220 430 480

9000m 600 km/h (360) 270 430 500

6000m 900 km/h (650) 290 530 620

6000m 600 km/h (430) 270 460 520

2000m 900 km/h (810) 430 800 930

2000m 600 km/h (540) 360 560 660

100m 900 km/h (890) 480 960 1130

100m 600 km/h (590) 420 660 750

 

 

To calculate fuel consumption for a given distance at a given altitude, divide the distance to travel (in km) by 100 and multiply that number by the basic fuel consumption for that altitude given here. Then compensate for wind.

 

 

TAKE-OFF AND CLIMB FUEL CONSUMPTION

(full AA load and 40% Fuel SU-33, no wind)

 

NORMAL TAKEOFF PROFILE

 

T-off with afterburner

Climb 7° nose up

cut afterburner when 900 (TAS) is reached (approx 1000m)

continue climb with 100% military thrust until 9000m

keeping a constant % of mach

stabilize at 9000m and 900 TAS (550 km/h IAS),

it takes approximately 1500 kg of fuel, 7 minutes and you travel 100 km.

 

If you takeoff and climb without any afterburner, you will eventually reach 9000m travelling a much greater distance, you will end up at a much slower speed but you will have burned only 1000 kg of fuel.

 

If the travel distance is relatively short, you may not have to climb so high.

T-off with afterburner

Climb 7° nose up

cut afterburner when 900 km/h (TAS) is reached

continue climb with enough thrust to reach 6000m at 900 km/h TAS, (650 km/h IAS)

It will take you 1100 kg of fuel, 4 minutes and yoy will have travelled 50 km

 

 

COMBAT EMERGENCY TAKEOFF PROFILE

 

T-off with afterburner, Climb with sustained afterburner, 20° nose up

To reach 6000m, you will use 1100 kg of fuel, in 2 minutes, travelling 17 km

To reach 9000m, you will use 1400 kg of fuel, in 2 min. 30 sec., travelling 26 km.

 

 

CAP (combat air patrol) FUEL CONSUMPTION

 

In order to stay a certain pre-defined time on station in a patrol, you can calculate thus :

Flying CAP at 6000m, 900 km/h TAS, (650 km/h IAS), you will burn 80 kg of fuel for each minute of CAP.

Flying CAP at 9000m, 900 km/h TAS, (550 km/h IAS), you will burn 65 kg of fuel for each minute of CAP.

 

 

COMBAT (AFTERBURNER) FUEL CONSUMPTION

 

In a fight, you will use afterburner to keep yourself in a good firing position or to defend yourself. (Always remember that the SU-33’s corner velocity, the one achieving the best turn rates without loosing too much energy, is 590 km/h IAS, it is a good idea in a fight to stay around and stlightly above that speed to be ready to react quickly).

 

With a full AA missile load and 40% fuel each minute of full afterburner will cost you

at high altitude (9000m) : 460 kg

at medium atlitude (6000m) : 640 kg

at low altitude (100m) : 1125 kg

 

In AA combat missions, one should always have some spare fuel for unexpected opposition.

 

 

DESCENT AND LANDING FUEL CONSUMPTION

 

Descent is done gradually from a given cruising altitude and airspeed, with a 3° nose down slope, throttle at idle, with air brakes to help slow down, usually with no more weapons than a couple of AA missiles left (AG weapons should be expanded ir jettisonned), and less than 30% of fuel left. The goal is to arrive close to the IAF (initial approach fix of the airbase, 18 km out) at around 1000m AGL and a little above 300 km/h IAS.

 

To descend from 6000m and 900 km/h TAS to pre-IAF conditions, it will take 3 minutes and 50 seconds, travelling a bit more than 30 km and using almost no gas (100 kg).

 

To descend from 9000m and 900 km/h TAS to pre-IAF conditions, it will take 5 minutes and 25 seconds, travelling a bit more than 45 km and using almost no gas (150 kg).

 

One should always keep some spare fuel for unpredicted wait in orbit, or bolter and try again (carrier landing)

 

 

WIND EFFECT ON FUEL CONSUMPTION

 

In Lockon, winds seem to have the following effect :

direct head wind of 1 meter per second augments fuel consumption by 0.5%.

One could say that the real life wind conditions would normally range from :

 

Calm 3.6 km/h (1 m/s)

gentle 18 km/h (5 m/s)

normal 36 km/h (10 m/s)

windy 54 km/h (15 m/s)

strong 72 km/h (20 m/s)

strorm 90 km/h (25 m/s)

 

One would only have to multiply the number of m/s by 0.5 and that will give the % of fuel consumption one has to substract (for a tail wind) of add (for a head wind).

 

 

TOTAL FUEL CONSUMPTION CALCULATION

 

Add the required amount for Take-off, climb, cruise, fight or attack, cruise back, descend and land, keeping some spare fuel for emergency (10% might be good), and apply the correction for the wind speed in each of these phases.

 

To calculate accurately the desired amount of fuel for the mission, one should first check the winds and calculate the correction for each phase of the flight according to the vector of the wind that is head-on (more fuel consumption) or tail-on (less consumption) to that particular path.

 

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JEFX

[Guest Cali]

You weren't kidding when you said it was a long post.

[Ironhand]

Okay. This is going to take some time to digest. You definitely put a lot of effort into it. Am I right in understanding that these numbers are only for the Su-33?

 

Rich

[Guest Cali]

Okay. This is going to take some time to digest. You definitely put a lot of effort into it. Am I right in understanding that these numbers are only for the Su-33?

 

Rich

 

Yep all test where done with the Su-33.

[Ironhand]

DUH!!! :doh: I somehow overlooked the heading:

SU-33 FUEL MANAGEMENT

(NAVIGATION AND COMBAT)

 

In my defense, I was reading while trying to get some tutorials out...

 

Rich

[Guest Cali]

DUH!!! :doh: I somehow overlooked the heading:

 

In my defense, I was reading while trying to get some tutorials out...

 

Rich

 

your forgivin :)

[AJ.eightFive]

While we're on the subject of fuel consumption... I did some extensive cruise performance testing for my squad in the F-15C last weekend and one thing I found is that the guages in the pit are completely inaccurate in reporting fuel flow. However, at a given power setting, fuel consumption varies linearly with altitude so it shouldn't be too difficult to calibrate the indicator properly and make it useful. Would be nice to see this working sometime in the not too distant future (hint hint BS *cough*) although I expect our beloved Eagle to be neglected once again.

[Yo-Yo]

2 JEFX

You have done a good job!

But you have a chance to make your investigation even deeper. Try to find MAXIMUM fuel effectiveness speed or speed range for the certain altitude, for example 9000 m and SL.

[JEFX]

Thanks Yo-Yo

 

I will give it a try if I have time this week-end.

 

JEFX

[JEFX]

2 YO-YO

 

I just made a quick test and the result is very interesting:

The test was made like my previous ones with:

a fully loaded AA SU-33 with 43% of fuel (approx 4000 kg).

at 9000m.

 

in these conditions fuel consumption varies this way:

 

1000 km/h (TAS) too fast, need to go into AB often to keep the speed

( it almost doubles the consumption)

 

900 km/h ; 430 kg per 100 km

800 km/h : 385

700 km/h : 385

600 km/h : 430

 

therefore, at this config and altitude, the best speed range for fuel consumption is between 800 and 700 km/h

 

 

JEFX