The turbos are coming! >:)

[gears]

Originally Posted by hoover

The upcoming Formula Two mod has been added to rF2 Rank, so those of you on the internal beta team can proceed to upload your laptimes.

Originally Posted by Tim Wheatley

Hoover adds it once he knows our car names used, really doesn't predict release, except this time he might be.

Devs are not having much fun with turbos, pain to do, but that will probably be the major feature added with the F2 that you guys have been waiting for from ISI for 10+ years.

http://isiforums.net/f/showthread.ph...-the-beans-%29

And from Twitter:

Something I noticed: Quickest way to drive a software engineer insane? Ask them to model Turbos.

https://twitter.com/rFactor2/status/226321117277728768

[pez2k]

Excellent, the one place where gMotor has always been behind is finally being improved. It's shaking off the last vestiges of being an F1-specific engine. This should really open things up for modders too.

[DoubleT]

I've always loved turbos. They really suit my driving style. Can't wait for this release. Lets hope they're properly simulated...without the 'silly' power-on means un-controllable spin characteristic most game developers put out. Turbos are fun to drive fast. They just require more controlled throttle per lap.

[davehenrie]

A long time ago, but not very far away, I had been told that RBR had the best Turbo effects. So I bought RBR just to try that out. I've NEVER opened the box. Been so wrapped up in another project that I just never had the time to fully explore it. I do hope ISI gets something other than just 'ramming speed' power.
dh

[WildBill]

OK---offtopic probably BUT the difference between turbos and superchargers-----turbos spoolup starting at a certain rpm----obviously it's been difficult to model properly------how would the torque and horsepower be modeled for a supercharger? It's either belt-driven or gear-driven and has nothing to do with exhaust pressure. The reason I'm asking is I'm trying to model a small supercharged engine. It would ALSO be contingent on engine rpm and there must be a blow-off vave otherwise you would fry your engine. hmmmm-----any thoughts? Torque and horsepower characteristics?

[davehenrie]

Probably a-lot of torque down low in the rpm band, and then, to simulate the pop-off valve, you reach a certain rpm and the torque curve collapses. Shifting prior to that point would be a must.
let us know if you suceed.
dh

[skiffle]

There seem to be a number of titles under development that are promising to bring in turbocharged cars - Assetto Corsa, for example, are currently working on a Lotus 98T ( http://www.bsimracing.com/2012/07/as.../#.UA_wWqPdddc ), not to mention the BMW E30 M3 (also turbocharged).

It'll be interesting to see how each side approaches the issue of modelling the action of a turbocharger, or, indeed, multiple turbochargers - will they be able to deal with things like sequential turbocharging, as was the case with Renault's F1 turbo engines and a number of modern road car engines?

[Niels_at_home]

I really hope they keep it (somewhat) simple!

[brrupsz]

Originally Posted by skiffle

Assetto Corsa, for example, are currently working on a Lotus 98T ( http://www.bsimracing.com/2012/07/as.../#.UA_wWqPdddc ), not to mention the BMW E30 M3 (also turbocharged).

E30 M3 had S14 NA engine. No turbo.

[skiffle]

Originally Posted by brrupsz

E30 M3 had S14 NA engine. No turbo.

I indeed stand corrected - I was mistakenly thinking of what turned out to be a homologation special that shared the same engine.

Either way, the main question I was asking was more along the lines of wondering how ISI intend to implement this feature, and how sophisticated will it be.
With their plans for making the environment behave in a more dynamic way, will that in turn have a greater impact on engine performance? For example, if the air temperature rises rapidly during a session, that should in theory have a detrimental impact on performance.

Or, as Niels hopes, will ISI opt for a simpler model that may only include some of those external influences?

[gears]

Originally Posted by skiffle

Either way, the main question I was asking was more along the lines of wondering how ISI intend to implement this feature, and how sophisticated will it be.
With their plans for making the environment behave in a more dynamic way, will that in turn have a greater impact on engine performance? For example, if the air temperature rises rapidly during a session, that should in theory have a detrimental impact on performance.

I don't know if this is specifically what you're talking about, but some modders have been tinkering with engine and tire files and they've found that weather will indeed affect the performance in terms of tire pressure, tire wear, horsepower and what fuel mix is needed. Humidity and altitude in particular will have affect on horsepower and tire pressure/wear.

[skiffle]

Originally Posted by gears

I don't know if this is specifically what you're talking about, but some modders have been tinkering with engine and tire files and they've found that weather will indeed affect the performance in terms of tire pressure, tire wear, horsepower and what fuel mix is needed. Humidity and altitude in particular will have affect on horsepower and tire pressure/wear.

That was along the lines of what I was wondering about - I kind of expected that some of those factors would be taken into account with the new tyre model, but wasn't sure if that would have an impact on the engines too.
From what you are saying, though, I take it that those factors are currently not operational in rF2's current beta state, right?

[gears]

Originally Posted by skiffle

From what you are saying, though, I take it that those factors are currently not operational in rF2's current beta state, right?

No, not yet.

[Vince Klortho]

I hope they parameterize the lag times at least with the turbos. Older cars with standard turbos had significant lag until the power really kicked in. Modern turbos are often "compound" turbos with a little one feeding a larger one because this greatly minimizes the lag. The point is not all turbocharged engines behave the same. With some of the Group 5 cars drivers had to learn how to "goose" the throttle in a corner to get the turbo spun up so they wouldn't be left in lagville when they exited the corner. It will be interesting to see how well different turbocharger behavior is simulated.

[skiffle]

Originally Posted by gears

No, not yet.

Sorry for responding to your comment so late, but thanks for expanding on that point.

The point about the effects of altitude does interest me because altitude effects are wider ranging than just engine power. There was a quite interesting article that Renault Sport put out a little while ago that talked about the impact of altitude at the Brazilian GP, given that circuit is around 800m above sea level.

The most obvious aspect was that the increased altitude cut the power by around 8%, but it also had a knock on effect on engine cooling (the reduction in air density means that there is a slight reduction in the efficiency of the cooling systems). Interestingly, though, the reduction in air density had a positive impact on engine life, at least for a normally aspirated car - the lower peak pressure within the combustion chamber lowers the stress on the mechanical parts.

The other aspect, which is somewhat forgotten, is that the reduction in air density has a noticeable impact on the aerodynamics of the car too. The reduction in air density reduces downforce and drag too - I wonder whether the rF2 physics engine could take that into account too, since that in turn would have a noticeable impact on the handling of the cars?

[Lunsmann]

That is an interesting point, I sure hope ISI do manage to nail the atmospheric conditions. Image the effect that would have on lap times at Kyalami considering it is at 2000m above sea level.

[davehenrie]

Originally Posted by skiffle

The other aspect, which is somewhat forgotten, is that the reduction in air density has a noticeable impact on the aerodynamics of the car too. The reduction in air density reduces downforce and drag too - I wonder whether the rF2 physics engine could take that into account too, since that in turn would have a noticeable impact on the handling of the cars?

Once upon a time, D3 was going to make an A1GP mod/game. I came up with an idea to simulate Mexico City's 1 mile altitude. I created an entire set of options via the rFactor upgrades that installed a detuned engine and less effective wings ONLY at Mexico City. I've been away from the rF scene for so long now, It would take me a year of experimenting, just to figure out how I did it back then.

[Chronus]

Originally Posted by skiffle

The other aspect, which is somewhat forgotten, is that the reduction in air density has a noticeable impact on the aerodynamics of the car too. The reduction in air density reduces downforce and drag too - I wonder whether the rF2 physics engine could take that into account too, since that in turn would have a noticeable impact on the handling of the cars?

To put that into perspective...

At 200 kph, 15ºC, altitude=0 m, a rear wing with the following parameters:

Camber = -2.0 % chord ,
Chord = 0.701 m ,
Span = 1.366 m ,
Surface Area = 0.958 sq m ,
Angle of attack = -5.0 degrees ,
Air Density = 1.224kg/cu m
Pressure = 101.261kPa,
Temperature = 15C,
Airspeed = 200 km/hr ,

results in the following:

Lift = -1336 Newtons
Drag = 236 Newtons

The very same wing at altitude=1500 m,

Lift = -1154 Newtons
Drag = 204 Newtons

Increasing the altitude to 3000 m,

Altitude = 3000 m ,
Air Density = 0.908kg/cu m
Theoretical Pressure = 70.106kPa,
Average Expected Temperature = -4C,
Lift = -992 Newtons
Drag = 176 Newtons

For a 3000 m race, the rear wing gets 40kgf less of negative lift (which can be offset by slightly wider rear wings), whereas its drag is reduced by less than 9kgf. This for a rear wing, obviously, though the same effects can be expected for splitters and diffusers.

So, we ought to step back, look at it carefully and understand that the effects of racing at high altitude are dramatic for the ENGINE ONLY (and probably tires).

[MickeyMouse]

I'm curious, where did you get those numbers?

If I just look at the standard lift equation:
L=Cl*p*v^2/2*A

If we assume the same temperature, humidity, sea level, wing, wing setting (AOA) and ground speed, the equation simplifies to just p.

~1.2 / ~0.88 = ~27% downforce reduction. I imagine the reason it isn't discussed much is that you can just crank on more wing and it's back to normal, but the engine isn't as adjustable.

[skiffle]

Originally Posted by MickeyMouse

I'm curious, where did you get those numbers?

If I just look at the standard lift equation:
L=Cl*p*v^2/2*A

If we assume the same temperature, humidity, sea level, wing, wing setting (AOA) and ground speed, the equation simplifies to just p.

~1.2 / ~0.88 = ~27% downforce reduction. I imagine the reason it isn't discussed much is that you can just crank on more wing and it's back to normal, but the engine isn't as adjustable.

That is along the lines that I was trying to make - the relative percentage drop in downforce is quite considerable, so I wouldn't dismiss it as being undramatic.

Yes, it is the case that you can compensate for it by adjusting your wings (although simply making them wider is often not feasible given that most racing series intentionally limit the width of a rear wing to indirectly control downforce production), but it is the case that racing teams would have to plan around that issue when working on their set ups (it was something that was an issue during the Mexican GP's held at the Autódromo Hermanos Rodríguez in the 1980's and 1990's, which is about 2,300m above sea level).

[Chronus]

Originally Posted by skiffle

That is along the lines that I was trying to make - the relative percentage drop in downforce is quite considerable, so I wouldn't dismiss it as being undramatic.

For 2300 m,

Lift = -1086 Newtons
Drag = 196 Newtons

Now, you factor in vertical load based on these numbers and you'll get the maximum lateral and longitudinal forces. Check it and see for yourself.

The performance of NA cars suffers greatly with increasing altitude. Turbo charged cars experience some loss, but not as great (unless the intercooler can't keep up or is not working as it should - which at higher altitudes is less likely to happen as air temp should decrease with increasing altitude).

To put this into context, at 5200 feet (roughly 1585 meters), the loss can be as high as 17%. Increasing altitude to 2030 m, the loss surpasses 21%.

A 333 hp NA car experiences around a loss of 67 hp - that car would turn into a 266 hp car.

I read somewhere a TC car, depending on the type of turbo, its positive displacement, etc, can expect a net pressure loss around 12% at 6000 ft.

In terms of performance, a racing driver will probably be able to offset the loss of downforce; he/she won't be able to compensate the loss of 30 to 67 hp.

[Monsoon]

Don't mean to troll but after reading this I think I just gained a IQ point. Anyway, the future for rF2 looks great and I hope to try it out soon, still fiddling too much with the old GTR2 atm tho.

I wonder if the game devs will simulate altitude, they could work out a standard formula for given altitudes and have the game automatically apply them to the physics when racing a given track. Each track could contain a height above sea level parameter (HASL?? lol) where the track creater/modder can punch in the height of the track. Just for example.