Hello all, This is my first post here. I was doing first laps with RR and rapidly I've noticed that vehicles lose a lot of speed when lifting the gas pedal. In some cars are more notorious than others and finally Ive decided to compare back to back with Assetto Corsa. I've compared with same car and same circuit, no wind, etc. Result is always same: RR cars lose speed faster than they do in AC. Video: I've also tested pressing the clutch, eleminiating the engine brake factor. Obviusly loses less speed but more than in AC. I've also tested with a similiar car in iracing and behaviour is similar to AC. I think this topic is quite important since it can affect a lot the natural behaviour of the car. I've noticed that RR is very difficult to recover a oversteer situation in a RWD cars. Maybe this could be one factor and correcting it the driveability could increase a lot! Iracing is also difficult to recover an oversteer situation but this is more a tire model problem and I think is not the case of RR. I read you. Cheers.
I agree both ac and iracing have it completely wrong , id just stick to comparing r3e to itself , much easier and avoids any confusion Andi
I don't know what other titles are doing, but we simulate the frictional losses of wheel bearings, drive shafts, differential gears and even the unloaded gearbox shafts rotating. That's just the mechanical stuff. There's also a lot of time and effort put in to ensuring aerodynamic drag behaviour is correct as well as tyre friction behaviour which is also affected by load, pressure, temperature and wear just to name a few factors. To press the clutch and barely slow down in a fairly draggy car with sticky tyres isn't a correct behaviour.
Hi Alex, Thanks for your answer. I have no doubt that you put a lot of effort calculating all the losses involved in a running car but it is a really difficult thing and I'm sure that in all cars there will be some assumptions that sometimes will be more accurate than others. I test real cars and I have some experience in this topic. For example: a quite stock car like the Porsche Cayman GT4 breaking at 0,1G in a 100-90kph coasting at R3E and it is a little bit too much. (I've tried it same straight up and down to get the average). In a real mid-size SUV this value is around 0,05G and I get similar numbers in AC, for example. Wasn't really my intention to bother or criticise R3E for fun. I just wanted to give my opinion in order to collaborate. Regards.
I agree, I have always thought the off throttle friction/engine brake felt a little too strong for many cars in R3E. It feels a bit too unnatural and strong for my preference or what I would perceive as realistic rolling friction simulation. Though, it does seem like it is a lot better than it used to be several years ago, imo. I just wanted to give my small .02 cents after reading the OP bc I have had the same opinion for a long time.
It's almost as if you think anecdotal observations are more important than actual data used by the devs to model this behaviour.....
Well, in all fairness, as almost every dev team claims to model their game based on actual data and still they differ tremendously, those "anecdotal observations" (I prefer - reality check) is all that we have left, right?
If we compare the GT4 Cayman 718 to a Volkswagen Golf, the Cayman will have something in the range of 15-25% more aerodynamic drag. As aerodynamic drag causes forces which grow exponentially that 15-25% difference has a growing effect as speeds increase. At 250kph the Cayman is subject to around 2050N of aerodynamic drag. The Golf at the same speed is fighting to overcome about 1600N of aero drag. The biggest contributor besides aero drag is tyre rolling friction. It's important to consider that a road car tyre has to balance several jobs - safety, noise, fuel efficiency. A racing tyre has one main task - to grip. That typically means that a racing slick has much higher rolling resistance than a road tyre. I have no numbers to compare the two because I don't have much road car tyre data. I however can safely say that a big share of a racing car's rolling resistance comes from the tyre/ground interface.
Hi Alex, Yes, you're totally right i what you say about aero drag and slick tires. I have no access to test a race car to feel that, but at 100kph the aero drag shouldn't too relevant between a road car and a racecar (thinking of a touring car like TCR). I really wonder if a slick tire could add 0,03 G of deceleration just in coasting. I had access a little data of a Leon TCR MK3 and in a coasting sceario at 180kph has around 0,2G of deceleration. No idea if there was slope or wind or other factors, but if it was quite flat and drag is exponential to speed, we could think that at 100kph we should have less than the half of 0,2G. Anyway, a pleasure discussing with you. Regards.
I have no numbers myself regarding this, but try sticking your hand out of the window of a car driving at 100 km/h and see if the angle at which you hold your hand makes any difference. Spoiler: it does! And racecars do not only have wings, they usually also have wider bodykits that add to the drag. Regarding the tyres, I have a bit of experience from my old days of karting. Even the little racing slicks of karts get ridiculously sticky when at racing temperatures. When you came from a hot racing session and stopped your kart at a spot on the tarmac and came back there to pick it up a minute later, you would have to literally rip the kart off the tarmac as the rubber actually sticks to it. And I'm totally not kidding here. You really had to rip it off. The same goes for the rubber left on the track. After a racing day, especially when it was quite hot, you could go to the raceline, mostly in corners, and find a layer of rubber there, several millimeters in thickness, and the moment you step on it, your shoes will stick to it. This rubber is all over the track - in corners more than on the straights of course, but still. So you're driving with sticky soft rubber over tarmac covered in more sticky soft rubber. Long story shot, racing slicks at good operating temperature are ridiculously sticky and thus have a WAY higher rolling resistance than normal street tyres. There is really no comparison between these two. Again, I have no numbers to calculate how much the difference really is, but I can tell you it's far from being irrelevant. So much for anecdotal observations...
Is it really a reality check tho, if you compare a road legal SUV on standard road tyres with a purpose-built racing car featuring aero parts that maximise downforce (and thus drag) and racing slick tyres? Just doesn't seem like a very scientific approach to me. Also, in case some aren't aware, there's this engine setting
Just revisiting this topic as I again came across the coast down data I mentioned earlier on in this book: When discussing GT3 aero testing, it provides a graph of a coast-down test of a GT3 car. Starting at 250kph the clutch is depressed and the time it takes to reach 150kph is recorded. It takes approximately 10 seconds. Repeated the same test with several of our GT3 cars in game, and the result was approximately 10 seconds for each one tested. I rest my case.
I find it inherently and unvoluntarily funny if someone critizeses the correctness of a simulation, not based on reality, but based on another simulation.
There's an entire cottage industry on YouTube of thinking "AC/ACC = reality" and then attacking other sims based on their imagined weaknesses.