Fuel Density - in which file is it documented

MerlinC

Tryed to find the fuel volumetric density [kg/Liter] rFactor uses for calculate fuel of from liters to weight and vice-versa.

Could not find any entry in HDV and Engine file? Does anybody know which file contains this parameter ?

Thanks in advance
 
I am afraid there is no parameter to set this on Rfactor.

I was interested in fuel weight for Rfactor, because fuel load doesn't seem to penalise lap times in realistic amount. This defficiency is known and checked, at least, on most of Formula 1 Rfactor mods.

For example, let's take Formula 1, 2013 season. Real lap time difference between Q3 and first laps of race (full fuel load) is aprox. 10-12%. This is around 6-8 seconds slower on race, depending on track.
However, Rfactor difference between Q3 and race is smaller. If you use the same fuel load as reality, you only have about 6-7%, or 4-5 seconds max difference.

I though the problem was that Rfactor fuel was too light. But i took telemetry measures of static tire loads with empty tank and also full tank. If i did it right, the vertical weight over tyres were absolutely correct on empty tank.
Then, after taking measures on different tank loads, i could estimate fuel weight and density, which would be around 0.72-0.77%. That would be correct for F1 fuels.

So, i think this is the value of density. However you can do yourself the measure with motec and share your result.


The reason for not enough lap times penalization is unknown for me, perhaps it is related with tire load sensivity and/or car inertias simulation....
 
I think tyre load sensitivity would be the most likely cause.
 
David Wright said:
I think tyre load sensitivity would be the most likely cause.
Click to expand...

Absolutely correct.

Most of the mods i have seen use very low tire load sensitivity and also some kind of speed correction, so it doesn't surprise me that lap times doesn't increase as much as in real world with a full tank.

Anyway, if the weight of fuel is more or less 0.72 kg/liter it is absolutely correct.
 
I did some testing with negative results for load sensivity changes on 'fuel load penalization' subject.

I made unloaded and loaded laps with these tyre values
LoadSensLat=(-4e-6, 0.36, 23400) // initial tyre load sensivity >>> this gives fuel load sensivity: 60% of real
LoadSensLong=(-4e-6, 0.43, 23400)

and then the same with these:
LoadSensLat=(-22e-6, 0.12, 14350) // much higher tyre load sensivity
LoadSensLong=(-22e-6, 0.15, 14350)

I guess last values i used were already too extreme, because i had to compensate big loss of grip with very high drylatlong values to get the same lap times on empty tank.
As i expected I also noticed wing setting changes hasn't almost any effect on grip or car balance, suffering big oversteer on high speeds, but more rear wing and less front wing didn't help.

However, even with such high load sensivity, lap time difference between loaded (210liters) and empty fuel tank were almost the same than before (3-3.5secs on Interlagos).

So, I would say tyre load sensivity is not the (only) problem.
 
Last edited:
Raintyre said:
I did some testing with negative results for load sensivity changes on 'fuel load penalization' subject.

I made unloaded and loaded laps with these tyre values
LoadSensLat=(-4e-6, 0.36, 23400) // initial tyre load sensivity >>> this gives fuel load sensivity: 60% of real
LoadSensLong=(-4e-6, 0.43, 23400)

and then the same with these:
LoadSensLat=(-22e-6, 0.12, 14350) // much higher tyre load sensivity
LoadSensLong=(-22e-6, 0.15, 14350)

I guess last values i used were already too extreme, because i had to compensate big loss of grip with very high drylatlong values to get the same lap times on empty tank.
As i expected I also noticed wing setting changes hasn't almost any effect on grip or car balance, suffering big oversteer on high speeds, but more rear wing and less front wing didn't help.

However, even with such high load sensivity, lap time difference between loaded (210liters) and empty fuel tank were almost the same than before (3-3.5secs on Interlagos).

So, I would say tyre load sensivity is not the (only) problem.
Click to expand...

In my opinion your approach is not right.

You should modele the tires to have exactly the same initial (so with 0 N of vertical load) grip coefficient and then only change how it decreases with load. To do so, you have to probably change all the tire coefficients, but you shouldn't do that by feeling. You should refer to the equations that the code use.

Moreover, as far as we know, it could well be that with full tank or with empty tank you were not at real limit of the car-tire. Finally, also car setup plays a role: it could well be that your lateral load transfer distribution works better with much fuel than with a low amount, then reducing the weight effect on final performance. This happens with a lot of road cars, for example.
 
>>>>You should modele the tires to have exactly the same initial (so with 0 N of vertical load) grip coefficient and then only change how it decreases with load. To do so, you have to probably change all the tire coefficients, but you shouldn't do that by feeling. You should refer to the equations that the code use.

Can you describe why? I'm not sure.. I don't think is neccesary to do that. I only wanted to check how high load sensivity we need to get realistic penalty to extra weight. But increase in load sensivity becomes unrealistic very soon. Any extra load over tyres becomes a disadvantage, reducing much grip and making wings unuseful, for example.
I did tests with many LS values, not only 2, also the intermediate and more extreme, but i've chosen the upper limit that still was driveable.


>>>>it could well be that with full tank or with empty tank you were not at real limit of the car-tire.
>>>>also car setup plays a role: it could well be that your lateral load transfer distribution works better with much fuel than with a low amount

You are right, but our test drivers are good finding the limit on every condition!
Setup also can cause differences, right, but we need to save a very big difference. 11% of penalization means 9 seconds on Barcelona, while in simulation we have only around 5. It seems to me that higher load sensivity can't enlarge to 4 extra seconds per lap unless we accept to include also very serious unrealistic effects.
 
Raintyre said:
11% of penalization means 9 seconds on Barcelona, while in simulation we have only around 5. It seems to me that higher load sensivity can't enlarge to 4 extra seconds per lap unless we accept to include also very serious unrealistic effects.
Click to expand...

Where are you getting your data? According to this site

http://www.f1fanatic.co.uk/f1-infor...t-de-catalunya-barcelona-circuit-information/

the penalty for one lap's worth of fuel is 0.075s. For a 66 lap race that's 5 seconds penalty for a full tank.
 
http://www.formula1.com/results/season/2013/897/7298/

Best Q3 times: 1:20.7 - 1:21
For comparison against race times perhaps we should add 1 second for qualy "pushing" driving style and 7 tens for DRS >>> in the worst case we have a 1:23

http://www.youtube.com/watch?v=Qp7MOFACyns
First laps times: 1:31

There are 8-9 seconds of difference. Car settings should be almost the same, unless there are relevant changes on the car permitted on parc ferme, i don't know them... This enormous lap difference is observed in all tracks
 
Raintyre said:
http://www.formula1.com/results/season/2013/897/7298/

Best Q3 times: 1:20.7 - 1:21
For comparison against race times perhaps we should add 1 second for qualy "pushing" driving style and 7 tens for DRS >>> in the worst case we have a 1:23

http://www.youtube.com/watch?v=Qp7MOFACyns
First laps times: 1:31

There are 8-9 seconds of difference. Car settings should be almost the same, unless there are relevant changes on the car permitted on parc ferme, i don't know them... This enormous lap difference is observed in all tracks
Click to expand...

I will reply in more details about tire load sensitivity later on today.

Anyway, i really don't think you should consider the first lap time for such a comparison.

I don't think that before 2 or 3 laps, drivers will ever be even close to the proper tire temperatures, pressures etc. Moreover, there are normally a lot of fights during the first lap and, finally, normally driver don't take too much risks the first lap, so it could well be they are not at the limit yet.
 
The race lap times are very artificial with current F1 because they have to save the tyres. The difference in lap time between race and qualifying is not just down to fuel load.

Check out race pace with full tanks and race pace on empty tanks.
 
Last edited:
>>>Check out race pace with full tanks and race pace on empty tanks.

Yes, it is strange, it seems they are saving tyres, engine, everything... I don't find explanation for such slow race times on empty tanks. If they push for one lap, can they really go 3 seconds faster?? (fastest lap on Barcelona is 1:26)
I think we are missing something... I will ask Pedro :3D
 
You must log in or register to reply here.

Back
Top