Once more - Train physics

[MrMurphy]

Few weeks ago I made series of tests on basic train physics. There has been lots of discussion about something is wrong with physics in RW but I never believed it's so out of realism. My tests were very simple everybody can repeat easily. Because I'm going on with testing day by day I start here with most easy ones. And easiest one is the test about locomotive free running (brakes on zero, driving direction handle in neutral position, controller on 0%). I created special test-track 5 kilometers long - 2 kilometers on flat ground then 1 km. with 5% grade and 2 km. flat ground again. Markers were placed where grade begins and ends to make a mesurements in right places. In my first test I placed German BR-101 electric locomotive close to the marker where the track just starts to go downhill. In scenario editor I made a path for locomotive so it has to run 1 km. downhill and then after additional 2 km.-s on flat ground finishes in the end of track. When scenario starts the only thing You have to do is to switch train/loco brake handle to 0% (no brakes) so locomotive can start to run freely downhill (5% grade). Where 5% grade section ends and flat ground starts mesure locomotives speed. In my test German BR-101 speed in this point was 45.1 km/h. After running freely more 1 km. on flat ground (0% grade) the speed was dropped to 43 km/h. Only 2 km per hour after 1 km. run! Okay I do not want to discuss here about is this speed right or not. Just lets go back to scenario editor and turn loco around so it has to do the same job but in reversed position. No other changes. Start scenario, move train break handle to zero and ... loco never starts to move. What's wrong? In reality loco has to roll back exactly the same way it was running downhill while placed to run forward. Seems like RW is still full of physics bugs like this. The same test was made with many other Ro-Ro (2 + 2 axles) locos available in RW (default and payware). In all cases setting loco to run backwards ended with failure. Now I started the same test with Co-Co locos (3 + 3 axles). Those locos do not roll freely even forward!! Is it really possible due to 2 additional axles friction between wheels and track is so big now that loco doesn't move at all? On 5% grade track downhill?? It's nonsense. Another tests were with loco pairs and different consist elements and I have to say no one of them gave acceptable result. Even no reasons to start to calculate something. This is sad knowing that RW3 is just around the corner and RSC team has said nothing about bugfixes and improvements in train physics. In current state RW is just like a laboratory for 3D modellers and nothing more. Only eye-candy. Physics side is unbelevably poor and inadmissible.
Best materials on train physics available: http://www.docstoc.com/docs/17693530/Ra ... nd-braking
I really recommend - please make the same tests and inform RSC development team about all those bugs You'll find. RW physics must get better.

[kevarc]

How did you calculate the physics? Back in MSTS days, I used Friction Calculator that is at T-S. It really changed the brake force and made a big difference.

I have a topic about the DB physics going, same issue, WAYYYYY to much force.

[MrMurphy]

How did you calculate the physics?

For calculation there are different materials available but in case I described above You don't need any calculations because You can say without that - it's a bug which needs fixing. If locomotive don't roll back on 5% gradient then what more can You say?

[kevarc]

Well, let's see if we can narrow the bug down.

What position was the reverser?

Do it for each direction the engine is headed, forward and reverse.

First do it three times headed forward downhill, each time with the reverser in a different position.

Then do it three times headed in reverse downhill, each time with the reverser in a different position.

Then start on the flat and run it up the hill, shut it down and see what happens. I would again do it headed in each direction and with the reverser in a different position.

[MrMurphy]

Well, let's see if we can narrow the bug down. What position was the reverser?

Seems like You didn't understand my point. I try to repeat - place any locomotive by Your choice on track with constant 5% grade (in England it's 1 to 20). Important: leave reverser in the middle position (neutral), do not accelerate (speed controller should be on zero position) and do not brake (both train and loco brakes have to be on zero position, not activated). Now loco has to roll downhill (at least 2+2 axle locos do) due to gravity and mass. Try this in case loco is facing downhill and in second attempt just turn loco around. There should not be any difference in real life is it going downhill nose or back ahead - it has to go anyway, gravity and mass are the same. But in RW loco rolls down only if faced to downhill. In reversed position nothing happens - locomotive stay in stationary position and this is totally wrong. You can do nothing to fix this. It's a bug in RW and very stupid bug.

[kevarc]

I DO UNDERSTAND - it is you who is misunderstanding what I am saying. All I am saying is try and experiment to see if it happens with other settings. It would make it easier for those with RW to narrow down where the problem may be in the coding.

[MrMurphy]

All I am saying is try and experiment to see if it happens with other settings. It would make it easier for those with RW to narrow down where the problem may be in the coding.

What do You want to achive with those different settings? There's no difference at all is the reverser switched to Forward, Neutral or Backward position. If brakes are not on and engines idling then loco has to roll downhill anyway no matter in what direction is it facing. It is what we call physics. So in my opinion game engines physics calculation module in RW is just faulty. And seems to be very faulty. How to fix it? We can do nothing. Only RSC can fix those problems. Maybe they've done something for RW3 but nobody talks.

[kevarc]

And you know this how> Have you tried it?

[arizonachris]

Guys, if I may. We are all end users. No need at all to get angry at things we have no control over. Eh? We need to sit tight and wait and see what RW3 brings us. Other complaints should be directed to RSC. Let's not spoil a great community here.

PS: in my experience, if my consist is on a grade, be it from the back or front, if I don't use brakes, it will roll. Use brakes. Problem solved.

[MrMurphy]

Guys, if I may. We are all end users. No need at all to get angry at things we have no control over. Eh?

Yeah, agree, lets be friendly. I'm not angry at all. Just wanted to know if anybody else has tested those situations to get confirmation I'm not only RW user havin' those problems.

We need to sit tight and wait and see what RW3 brings us. Other complaints should be directed to RSC.

Yes I have informed RSC about bugs I've found. I'm sure they didn't know such a weird bugs are existing.

PS: in my experience, if my consist is on a grade, be it from the back or front, if I don't use brakes, it will roll.

Question is not in consist. Yes I know consist will roll back (thereby locomotives mass is not taken in count). Test it with locomotive only and You can see the difference. Sounds strange but it's true.

[arizonachris]

Test it with locomotive only and You can see the difference. Sounds strange but it's true.

I usually don't do free roam, but I suppose I could to test this out. I'm still gonna say, without brakes, it's gonna roll whatever direction the grade is.

Kinda busy with the beautiful new Gensisi right now. I'll give it a run later!

[MrMurphy]

I usually don't do free roam

I tested in standard scenarios and not in free roam.

I'm still gonna say, without brakes, it's gonna roll whatever direction the grade is.

I think the result will be surprising for You. I recommend to test with 4 axle and 6-axle locos.

Kinda busy with the beautiful new Gensisi right now.

Agree. Genesis pack is very good. I like it.

[Kali]

Sorry, case not proven.

I took a default 37, and a default HST powercar to the 1:50 outside Bath green park ( so all default items ), and they both roll away down the hill in either direction with all your other conditions met.

[arizonachris]

Murph, no disrespect ment at all, but I don't dwell on counting the rivets. A lot of people here do. I just kinda like to play and drive. I try and not let little issues bug me, and trust me, there are a lot of little issues. Been enjoying this sim for quite a while now. There is not one single game I own that is 100%. That's just the way it is. Try and have some fun, eh?

[Kali]

Well, each to his own; I rather like it when sims behave in a predictable true-to-life manner, it makes me more involved. Content is sometimes less important than polish.

In this case however I think it might be the content at fault; I'll try the german stock sometime, but the UK stuff looks to be working fine for this.