Avio Posted September 23, 2023 Posted September 23, 2023 I noticed each time I full brake the jet to a complete stop, the last couple of seconds would always see the jet veering its nose heading about 5 degrees either to the left or right before coming to a complete stop, even though there was no rudder input whatsoever. Anyone else noticed this? Could it be a bug?
razo+r Posted September 23, 2023 Posted September 23, 2023 Perhaps you managed to lock up your wheels and thus are skidding in a direction?
jaylw314 Posted September 23, 2023 Posted September 23, 2023 Antiskid is less effective below 30 knots, so keeping heavy braking could result in wheel skid
Avio Posted September 25, 2023 Author Posted September 25, 2023 It was just a normal slowing down before coming to a complete stop, so skidding should not be in play. The nose veering to one side happens when stopping on runways. Did not seem to happen when outside of runway. Maybe it is the unevenness of runway that causes it.
razo+r Posted September 25, 2023 Posted September 25, 2023 1 hour ago, Avio said: It was just a normal slowing down before coming to a complete stop, so skidding should not be in play. The nose veering to one side happens when stopping on runways. Did not seem to happen when outside of runway. Maybe it is the unevenness of runway that causes it. Got a short track?
Avio Posted September 25, 2023 Author Posted September 25, 2023 4 hours ago, razo+r said: Got a short track? Two tracks here -- One is a full Rwy strike mission, where after landing back at Ovda the full-stop brake veering was rather bad, going off by several degrees. The other shorter track was just moving around the base. That one exhibits only very slight veering off. It seems whenever a longer mission is run, the veering off would show up more. F15E Ovda Short.trk F15E Ovda.trk
Avio Posted September 27, 2023 Author Posted September 27, 2023 Anyone else noticed this brake stopping problem? Does not show up much in beginning, but becomes very pronounced after a longer mission. Looking rather positively to be a bug.
razo+r Posted September 27, 2023 Posted September 27, 2023 Unfortunately, I cannot take a look at your tracks because it's on the Sinai map that I don't have. So instead I've tried with a hot start on the runway with accelerating and then coming to a stop. I have not encountered any skidding there. I'll report back once I'm doing a longer sortie.
Avio Posted September 28, 2023 Author Posted September 28, 2023 11 hours ago, razo+r said: Unfortunately, I cannot take a look at your tracks because it's on the Sinai map that I don't have. So instead I've tried with a hot start on the runway with accelerating and then coming to a stop. I have not encountered any skidding there. I'll report back once I'm doing a longer sortie. No it is not skidding, more like the jet comes to a stop with the nose having to veer a few degrees to the left or right, instead of straight ahead as it should. And it becomes very obvious only after a mission has been flown for a certain duration. Hot starting and rolling about a little hardly shows up that problem, if any. Most usual bug, if that is one.
WizzRD Posted September 28, 2023 Posted September 28, 2023 5 hours ago, Avio said: No it is not skidding, more like the jet comes to a stop with the nose having to veer a few degrees to the left or right, instead of straight ahead as it should. That´s really something I have in any other jet but not in the F-15. For me it´s the most centric, easy to brake plane I own. My missions are in the 1.5 - 2 hrs region (and mostly MP) if that´s of any importance.
rem27 Posted September 28, 2023 Posted September 28, 2023 6 hours ago, WizzRD said: That´s really something I have in any other jet but not in the F-15. For me it´s the most centric, easy to brake plane I own. My missions are in the 1.5 - 2 hrs region (and mostly MP) if that´s of any importance. +1 Intel® Core i7-7700K @4,20GHz - 64 Go RAM - GeForce GTX 1070 Ti - Windows Pro 64 bit - Stream Deck - HOTAS Warthog
Avio Posted September 29, 2023 Author Posted September 29, 2023 19 hours ago, WizzRD said: That´s really something I have in any other jet but not in the F-15. For me it´s the most centric, easy to brake plane I own. My missions are in the 1.5 - 2 hrs region (and mostly MP) if that´s of any importance. Totally agree it is about the sweetest handling module in the air or on the ground …. Until that last second stopping weirdness, as seen in the longer track i posted earlier. Not a deal-breaker for sure, but would be nice if that is fixed.
draconus Posted September 29, 2023 Posted September 29, 2023 2 hours ago, Avio said: Until that last second stopping weirdness You'd be better off with a short video. Was the jet even balanced in loadout? Any crosswind? Brakes full or partially applied? Win10 i7-10700KF 32GB RTX4070S Quest 3 T16000M VPC CDT-VMAX TFRP FC3 F-14A/B F-15E CA SC NTTR PG Syria
Avio Posted September 29, 2023 Author Posted September 29, 2023 1 hour ago, draconus said: You'd be better off with a short video. Was the jet even balanced in loadout? Any crosswind? Brakes full or partially applied? Balanced, zero wind, full brakes. Not sure is it a Sinai problem. Will see if it still happens at other maps, if i fly them.
Avio Posted September 29, 2023 Author Posted September 29, 2023 15 hours ago, draconus said: You'd be better off with a short video. Was the jet even balanced in loadout? Any crosswind? Brakes full or partially applied? Got a short track here -- this one hotstart on runway at Beirut. Brake stop problem right from the start. Couldn't be my pedals issue, because as shown, the initial brake slowing was perfectly smooth and straight. It was only the final moment when the plane came to a stop that the nose just had to swivel to one side, sometimes by quite some degrees left or right, seemingly randomly. Yet at other times, braking was smooth and straight with no problem. Really usual. Hope this could be looked into. F15E Syria.trk 1
razo+r Posted September 29, 2023 Posted September 29, 2023 Looks indeed like yet another aircraft with weird anti skid/friction. 1
Rainmaker Posted September 30, 2023 Posted September 30, 2023 Zero things perceptively wrong in your track. You are in a skid. The resolution to that is not standing on the brakes at low speed. 1
razo+r Posted September 30, 2023 Posted September 30, 2023 2 hours ago, Rainmaker said: Zero things perceptively wrong in your track. You are in a skid. The resolution to that is not standing on the brakes at low speed. His wheels are not locked up. 1
Rainmaker Posted September 30, 2023 Posted September 30, 2023 22 minutes ago, razo+r said: His wheels are not locked up. That's not what a skid is. A skid is wheel speed vs overall velocity. The two are not necessarily the same thing. You are looking for the wrong things to make that determination.
razo+r Posted September 30, 2023 Posted September 30, 2023 21 minutes ago, Rainmaker said: That's not what a skid is. A skid is wheel speed vs overall velocity. The two are not necessarily the same thing. You are looking for the wrong things to make that determination. Care to explain a bit more? I was under the impression that in order to slow down a tire has to be a bit slower than the object. But if it starts to lock up you skid. And thus there should be a visible indication during skidding. 1
Rainmaker Posted September 30, 2023 Posted September 30, 2023 (edited) 5 minutes ago, razo+r said: Care to explain a bit more? I was under the impression that in order to slow down a tire has to be a bit slower than the object. But if it starts to lock up you skid. And thus there should be a visible indication during skidding. Its the same as I just noted above. A tire does not have to be 'locked up' in order to skid. A skid is the tire being slow enough to cause a loss of friction. IE the wheel just moving too slow. It does not have to lock up to do that. No different than the opposite and stepping on the gas in a car and breaking traction the opposite way. Edited September 30, 2023 by Rainmaker
jaylw314 Posted September 30, 2023 Posted September 30, 2023 Watched @Avio's track. How are we determining the tires are not skidding? Given the way you can do airplane drifting in DCS, I'm guessing you can't really base that on seeing the tires lock up or slow down. I mean, it's not Assetto Corsa Is there a way to identify wheelskid in the interface, like the external info bar? I couldn't find one. OTOH, why stand on the brakes to a full stop? antiskid is supposedly less effective as I mentioned before. Aside from asking for skidding and flat spots, it's EXTREMELY uncomfortable and probably bad for the equipment. Yeah, I know it doesn't matter in DCS, but brake like you have passengers, and let up on the brakes before you come to a complete stop. Otherwise I suspect your virtual WSO will start throwing things at you 2
Avio Posted October 1, 2023 Author Posted October 1, 2023 My understanding - a skid occurs when static friction is exceeded and kinetic friction takes over, so from wheels surfaces being static relative to ground when rolling properly to when wheels surfaces starting to slide (skid) over ground (kinetic friction region) when in a jam brake for example. The subject problem here happens even when plane already slowed to very slow speed prior to braking, that the friction should be well within the static region, and should not skid. In any case, how should we explain those occasions at start of fresh missions when even at higher speed, full standing on brakes brought the jet to a nice, straight stop with no veering of nose at all? Something just doesn’t quite square here. 1
Rainmaker Posted October 1, 2023 Posted October 1, 2023 3 hours ago, Avio said: My understanding - a skid occurs when static friction is exceeded and kinetic friction takes over, so from wheels surfaces being static relative to ground when rolling properly to when wheels surfaces starting to slide (skid) over ground (kinetic friction region) when in a jam brake for example. The subject problem here happens even when plane already slowed to very slow speed prior to braking, that the friction should be well within the static region, and should not skid. In any case, how should we explain those occasions at start of fresh missions when even at higher speed, full standing on brakes brought the jet to a nice, straight stop with no veering of nose at all? Something just doesn’t quite square here. Different fuel weight, CG location, etc. its all dynamic. And you have a 40K airplane and two tires, if you think you are just going to stop in those cases well then…. Anti skid is inoperative below about 15 knots. Doesn't exist. 1
jaylw314 Posted October 1, 2023 Posted October 1, 2023 (edited) 4 hours ago, Avio said: My understanding - a skid occurs when static friction is exceeded and kinetic friction takes over, so from wheels surfaces being static relative to ground when rolling properly to when wheels surfaces starting to slide (skid) over ground (kinetic friction region) when in a jam brake for example. The subject problem here happens even when plane already slowed to very slow speed prior to braking, that the friction should be well within the static region, and should not skid. That doesn't square up with the physics I know of. You can skid at any speed, the maximum brake force doesn't decrease with speed. Just go to any parking lot in the US, wait a few minutes and somebody will slam on the brakes and skid, even if it's really brief due to ABS. Edited October 1, 2023 by jaylw314
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