Tyres still burst for unknown reasons - BUG

[Dr_Arrow]

Although I feel that I am fairly proficient in correctly taking off with Mig-21BIS using procedures from the RL and game manual, I still get burst tyres from time to time, even though I have not violated any takeoff parameters. As you can see in the picture, an empty Mig-21BIS bursting tyres at 320 km/h with correct takeoff attitude (11 degrees of AoA according to UUA). In this case the front wheel was lifted at a around 295 km/h (little bit later than it should). However there is no reason for a tyre burst at 320 km/h with an empty plane. This is happening using the latest OB, no MODS. I just cannot figure when do the tyres burst to reliably avoid the condition. I think it might be some kind of suspension bug. Track attached.

 

 

Another example, when the tyres burst at 302 km/h at correct takeoff attitude with attached track:

 

Mig-21_tire_burst.trk

Mig-21_tire_burst2.trk

Edited July 13, 2020 by Dr_Arrow
Added information

[Frederf]

I found that "gentle" unsticking could cause tire failure even when below the rated tire speed limits. Non-afterburning takeoffs are especially prone to this because the unsticking is less positive.

 

My guess is one of two things are happening: damage to the tires is a function of speed and time so prolonged rolling at high speed (but still below the tire limit) will eventually destroy them. Normal takeoffs don't spend enough time in this speed regime to deplete the health bar of the tire before a liftoff occurs.

 

Second idea: gradual liftoffs do some kind of rapid contact-noncontact with the surface cycle. So your one liftoff is actually several, dozens, maybe hundreds happening very quickly And somehow the health bar of the tires depletes with every transition blowing up on what appears to be a single takeoff.

 

These are just ideas but testable. The first one would happen by taxiing very fast but without attempting to lift off while the second would require a liftoff attitude. Both would require raising the nose tire at least a little to avoid blowing that if you wanted to test at the speeds above that tire's limit.

 

I'm also curious if the "tire health bar" is persistent and is it noticeable after several consecutive takeoffs and touchdowns.

[Dr_Arrow]

Thanks Frederf, that might be it, there is maybe some contact-no contact with the surface cycle.

 

For devs: Tyres health it is probably not a good approach in their modeling. Even more when you manage an excellent smooth take-off and you get rewarded by burst tyres :( Something like a function of burst probability/ground speed would in my opinion bring much more realistic tyre burst results, or if they are working with tyre health just tie it to ground - speed and not take-off/landing cycles. I hope it finally gets looked at, because it is something I remember to happen as long as I have Mig-21BIS (bought in pre-purchase campaign).

Edited July 15, 2020 by Dr_Arrow

[ShaunX]

I found that "gentle" unsticking could cause tire failure even when below the rated tire speed limits. Non-afterburning takeoffs are especially prone to this because the unsticking is less positive.

 

My guess is one of two things are happening: damage to the tires is a function of speed and time so prolonged rolling at high speed (but still below the tire limit) will eventually destroy them. Normal takeoffs don't spend enough time in this speed regime to deplete the health bar of the tire before a liftoff occurs.

 

Second idea: gradual liftoffs do some kind of rapid contact-noncontact with the surface cycle. So your one liftoff is actually several, dozens, maybe hundreds happening very quickly And somehow the health bar of the tires depletes with every transition blowing up on what appears to be a single takeoff.

 

These are just ideas but testable. The first one would happen by taxiing very fast but without attempting to lift off while the second would require a liftoff attitude. Both would require raising the nose tire at least a little to avoid blowing that if you wanted to test at the speeds above that tire's limit.

 

I'm also curious if the "tire health bar" is persistent and is it noticeable after several consecutive takeoffs and touchdowns.

I had been experiencing front wheel tyre blowout on almost every single takeoff in a fully loaded F-15C. Assumed it was just my incompetence and so tried again and again varying acceleration, T/O Trim etc with no success. Then I realised that it was always occuring while accelerating over the central area of the runway which had the expanse of black rubber deposit. I altered my takeoff path to the side of the runway, avoiding the rubber and I have not had a blowout since. Perhaps your rapid contact-nocontact theory is taking place while accelerating over the rubber ?