4.12m sneaky P-38 fm changes
 

I just noticed p-38's compressibility issue above 650km/h is gone.
Plus there are some discrepancies between trim settings.
Is this work as designed or someone made a mistake?

Not really, compressibility issues bellow 0.63 Mach are gone.

What discrepancies? I don't remember any changes in P38 trim settings in 4.12.

Compressibility works as designed and for trim I can't say when I don't know what trim changes you are talking about.

I did some test flights,it seems now you don't need to worry about compressibility ever if you fly below 7500m,really you could dive straight to the ground and never experience serious compressibility.
Starting from 10000m though,it does exhibit compressibility at around 8km,but even then when you get close to 4.5km,you can again control your plane.
Either
1.the compressibility effect is under-modelled,actually by using http://www.globalaircraft.org/converter.htm and compare against in game speed using open cockpit TAS gauge,i think it only get into uncontrollable dive above 0.8 mach.
2.or speed of sound is overestimated,yeah high precision mach number vs altitude/temperature is the thing that get classfied,and i'm totally a layman on this,but it can't be that far apart does it?
3.i just made a mistake in my assumption related to mach number because i'm a layman,but i tested in hot map(Coral Sea) and cold map(moscow),and it's all the same,below 4.5km you are immune,and not that pronounced above that.
4.or that the non-pronounced compressibility effect is modelled without considering every sim player can fly with joystick like they have hydraulic assists,and this game have not so accurate modelling of trims(actually much like a seperate low drag control surface,especially at low speeds,this solve the problem of uneven feels of moving main surface in opposite direction,exhibited if you simply model trim as main surface offset,but it can be exploited in certain situations where main surface should be too draggy to be usable.)

For trims,it looks like now trim is off by -3% compared to previous setting.
For 110% throttle Sea Level level flight with 50% fuel on Coral Sea Online map,
previously you need -23% trim,now you only need -20%,
For climbing at best climb rate speed,it was +15% trim previously,now it is +12% trim.
They have same max speed at sea level in 4.11 and 4.12.
It is a change for the better,now you don't get annoying pitch up when aiming using default trim,but i think this warrant a entry in change logs.

That's basically how things should be. Compressibility was a problem at high altitudes only. Considering that Mach drag calculation is improved in 4.12 it is not surprising that there is less problems with compressibility at low altitudes simply because plane don't dive as fast as before.

1. Model is fine on fundamental level, refinements are always possible.
2. Mach number is OK, nothing wrong with it, precision is actually increased in 4.12.
3. Don't know but it doesn't really matters.
4. Refinements are always possible.


AFAIK there were no changes in trim parameters, any possible difference in handling is result of something else.

I mean dive from 7500m straight down all the way,and you at no time loss controllability,it does pitch down in relative terms but you still have good response on elevator main surface,and at no time is default trim pitching down in absolute term.
I can recover with 15% pitch up on elevator main surface from 940km/h TAS at 3000m(open-cockpit TAS gauge),way past mach 0.68,if it is truly modelled correctly,then it surely stretch my imagination a bit...
https://en.wikipedia.org/wiki/File:C...ibility010.png

Start dive from 10000m,when at 6km with 360mph IAS,i do get very apparent compressibility,but dive from 7500m,when at 3km with 420mph IAS,i can still control it no problem.
IAS read from in-cockpit gauge,speedbar reading is higher.

Do you read my posts?
BTW what is this sudden obsession with P38? It was wrong for years and now when it is more accurate you felt the need to "join" the forum and question its FM. Not that it is wrong to question the FM but the timing is interesting.

Because i was in the process of testing trim and control settings for maximum maneuverability,after i become more conscious about certain factors after warthunder experience,pretty much power gaming really.
Then i just accidentally stumble upon p38 fm changes because a certain map on sov only have p51 and p38 on red side.
Then because i actually have something to discuss so i registered,and because sometime ago i bought il2 1946 on GOG.com,previously i did play pirated copy for a while because back then real shop selling real game mostly disappeared,and even if there is one,none have ages old games in stock.

Background aside,i did read your response fully,my conclusion is that mach number below 5km is a bit off,although algorithm might be improved,so it's a good start but right now the problem is one of tactical,simply that p38 won't experience any compressibility in real game sessions.

Mach is fine, there is not much that can go wrong with it. I tested P38 after your first post and it can be affected by compressibility a bit more. In one of the next patches(4.13 most likely) its FM will be changed a little.

As for tactic, you can't expect compressibility at low altitudes, plane just can't fly fast enough to get into compressibility. If you are used to FM prior to 4.12 than just forget it, it was flawed on fundamental level and worked just the opposite of how things work in reality.

OK,reenact within current model match following info pretty closely.
http://forums.ubi.com/showthread.php...ibility-Forums
So i guess it is mostly a hydraulic elevator for everyone problem..
You just don't need trims to recover.
Whether to implement further hinderance is a decision for developer.