Major wind/performance bug in 1.5.8

[bbrz]

-

Edited April 8, 2018 by bbrz

[msalama]

So what's the average / very rough RL difference then, if we disregard fineties such as altitude and temperature? Since you do need more power in a headwind for a given groundspeed, do you not?

[Ironhand]

There's apparently a pretty basic major bug in the DCS wind/performance modelling.

 

A plane in DCS needs noticable more power when flying with a headwind than with a tailwind which isn't correct.

 

E.g. the F-15 flying at 250kias at 2000ft requires 75% RPM in a 50kts tailwind, but 80% in a 50 kts headwind.

 

Btw, the F2 status line can be toggled between IAS and TS. IAS is correct, but TS is actually GS.

The only error that I see is that the Info bar mislabels the GS as TAS. In the Su-27 cockpit, the instuments indicating IAS, TAS, and Mach read correctly. E.g.: Flying at 2000 meters at an IAS of 743 on the info bar with a 50 m/s (180 km/hr) headwind yields the following values in the cockpit: IAS: 743, TAS: 820, Mach: 0.69 all of which are correct. The info bar, OTOH, indicates TAS: 642 which is actually your ground speed.

[msalama]

This is about constant IAS/TAS.

 

But indeed. For some reason, I thought we were talking about the ground speed. Sorry, my bad.

[Ironhand]

Again, that's not the problem. You will notice that if you are flying (constant IAS/TAS/M) with a headwind component you need considerable more thrust than when flying with a tailwind component.

 

That's simply impossible and a rather serious bug IMO which I've never seen in any other sim.

If I fly at the same IAS (using my brand shiney new T1.6000) with either a 50 m/sec tailwind or headwind or no wind at all, the Su-27's throttle settlings are within 1% of each other. So the Flanker seems fine.

 

No wind:

 

 

 

50 m/s Headwind:

 

 

 

50 m/s Tailwind:

 

[Precog]

:huh:

There's apparently a pretty basic major bug in the DCS wind/performance modelling.

 

A plane in DCS needs noticable more power when flying with a headwind than with a tailwind which isn't correct.

 

E.g. the F-15 flying at 250kias at 2000ft requires 75% RPM in a 50kts tailwind, but 80% in a 50 kts headwind.

 

Btw, the F2 status line can be toggled between IAS and TS. IAS is correct, but TS is actually GS.

 

Wind has no affect on IAS. It should be the same value no matter what the wind is doing.

[Paganus]

What about drag? Is it a consideration?

[Ironhand]

That's a diffcult bug to track. Tried to replicate it on another F-15 flight, no wind bug.

 

I've discovered this problem the first time with the F-5 and it seems that this bug appears on every flight as a 'player'. The AI F-5 doesn't have this problem.

 

Out of 5 flights I could reproduce this error with the F-15 only once, immediately after flying the F-5.

 

Didn't the Viggen have a similar problem?

 

btw congrats for your T16000M :)

 

 

 

That's what I'm saying...or trying to say...

Intersting. Hopefully you can find some time to nail it down a bit more. Also, nice find on the F2 Info bar. Had never noticed the TAS/GS differences you've pointed out.

 

:) Definitely like the new stick and throttle. Noticed right off how much more range there is on the throttle compared to the X-52. Much easier to fine-tune speeds due simply to that. And a nice firm feel to everything.

[NeilWillis]

Is there a reason you have asked this same question separately for a different airframe? Hoping to get better results by multiple threads?

[Yo-Yo]

I can say more: this speed is not even a GS, it is world velocity vector length... As the F2 string was being developied generally for ISA speed tests, the difference did not played a great role, and as this speed was much easier to drag through the project it was used.

The problem is known (frankly speaking I found it accidentally not more than a month ago :) ) and will be fixed, I hope.

[Ironhand]

I can say more: this speed is not even a GS, it is world velocity vector length...

Ahhh... That's why the "GS" value was always off by a few km/hr in my quick experiments. It's not a GS value at all.