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[REPORTED] serious headwind/tailwind bug


bbrz

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Isn’t this a MASSIVE flaw that should be promptly addressed by ED? How is it possible that they didn’t do anything about, didn’t even see this thread probably!

 

ED's attitude certainly seems to indicate that they consider the F-5E complete and bug-free, when the reality is that it is anything but. We're still missing the range indicators on the radar scope. Some RWR functions remain inaccurate. Nose wants to drop more on landing than actual T-38 pilots say it would or videos of the real jet indicate. The first 2 are thankfully fixed by mods, but the 3rd along with this definitely cannot be until ED finally takes more than a cursory look at this module.

 

It's all fairly annoying when the F-5 is one of your favorite aircraft to fly in the sim. Maybe if ED gets around to that cockpit update/capability upgrade to which Wags alluded in that one interview they'll include some bug squashing. Until then, I guess I'll just always set the environment to no-wind, standard day.

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The sad thing is that with all the new things ED is planning for 2020, I'm afraid that correcting bugs on old modules will now take even longer.

 

Unfortunately re-installing DCS doesn't seem very likely for me in the foreseeable future :( :(

i7-7700K 4.2GHz, 16GB, GTX 1070 

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Yeah but this is not just any bug, it's a massive simulation error.

Now I understand why I get huge RPM fluctuations when crossing the altitude at which wind speed changes (you know, when in ME you can set 3 wind-speed and directions at 3 different levels).

I mean, this is nuts!

Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s

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Has anybody actually a PMed a mod so they see this report?

 

Also BK. Post a track of you getting RPM changes as you go through a different wind layer.


Edited by Deano87

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My Fathers Aviation Memoirs: 50 Years of Flying Fun - From Hunter to Spitfire and back again.

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Thinking out loud. Flying into a head will increase the speed of wind thus amount of lift under your wings but could potentially decrease your relative airspeed. The opposite is also true no? Strong tail wind along with fast relative movement of the plane decreases the amount of wind going under the wing decreasing lift??

Kind if like flying a kite. When you pull it upwind or hold the string, it stays put and climbs. However if the string breaks, the kite “flys” downwind but looses altitude and hits the ground.

Not suggesting I have your answer, just trying to think thru it....

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Thinking out loud. Flying into a head will increase the speed of wind thus amount of lift under your wings..

No. That's a common misconception. (Steady) wind has absolutely zero effect on an airplane in flight except for ground speed and track over ground.

 

Concerning kites; I kite is connected to a fixed point on the ground, so it's not even remotely comparable to an aircraft in any case.

 

Furthermore lift is usually created above, not under the wings.

i7-7700K 4.2GHz, 16GB, GTX 1070 

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Thinking out loud. Flying into a head will increase the speed of wind thus amount of lift under your wings but could potentially decrease your relative airspeed. The opposite is also true no? Strong tail wind along with fast relative movement of the plane decreases the amount of wind going under the wing decreasing lift??

Kind if like flying a kite. When you pull it upwind or hold the string, it stays put and climbs. However if the string breaks, the kite “flys” downwind but looses altitude and hits the ground.

Not suggesting I have your answer, just trying to think thru it....

 

That would be true if the airplane was pulled on a string by a man with his feet on the ground with equal ground speeds with and against the wind. If there is 10 knots of wind and the airplane flies back and forth at 100 knots ground speed each way then yeah, it's going to be 90 knots of airflow one way and 110 knots of airflow the other.

 

But that's not how unaccelerated vehicles propelling themselves through a fluid medium act. For a given power setting flying back and forth it's the airspeed that's constant and the ground speed which varies.

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Has anybody actually a PMed a mod so they see this report?

 

Also BK. Post a track of you getting RPM changes as you go through a different wind layer.

 

Hey Deano, I would but I saw this effect on the AO server, a track of that would be pretty useless.

Maybe I can re-create it in a single mission.

 

 

EDIT: couldn't re-create the RPM fluctuations in SP, however I tested with headwind/tailwind and there is indeed a difference in both top speed and fuel flow.

 

at 11.000 ft with a 97kts tailwind: top speed 518 kts, fuel flow 3300lbs per engine

at 11.000 ft with a 97kts headwind: top speed 510 kts, fuel flow 2800lbs per engine.

F-5 wind-engine-bug.trk


Edited by bkthunder

Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s

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EDIT: couldn't re-create the RPM fluctuations...

As mentioned a few times already, the rpm difference isn't noticeable at high speed where the engine is apparently operating at or close to max rpm.

 

Suggest to run the test again at 250kias.


Edited by bbrz

i7-7700K 4.2GHz, 16GB, GTX 1070 

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As mentioned a few times already, the rpm difference isn't noticeable at high speed where the engine is apparently operating at or close to max rpm.

 

Suggest to run the test again at 250kias.

 

I don't see the RPM changes, however, I did a further test (track attached) and the difference is absolutely enormous!

 

Set up was: wind 97 kts

Engine RPM: I maintained 80%

Altitude: 11.500 (inside the wind layer I set up)

 

head-wind: the airplane cannot sustain flight with engines at 80%, the speed drops below 150 and keeps dropping.

 

Tail-wind: I can reach 400kts with engines at 80%.

 

Man, ED really needs to take a look at this! :doh:

 

 

EDIT: just tested, the F-16 has the same issue. will post in the relevant section.

F-5 wind-engine-bug2.trk


Edited by bkthunder

Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s

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Hello,

 

 

Roughly reproduced this bug.

 

 

SP mission with F-5 and A-10A (since it has thrust issues too).

 

 

Wind @75kts from 000 at all alts except at surface (33kts).

 

 

Spawned at 11.5K'. Unable to maintain speed or altitude into the wind at 000 HDG at 82%Ng.

 

 

 

Turned to 180 HDG, advanced thrust to get back to ~11.5k and stable, then reduced power again. Able to comfortably maintain 250kts IAS and 11.5k'.

 

 

 

Turned back to 000HDG with no changes to inputs, unable to maintain altitude or speed at 82%Ng.

 

 

 

Including track with A-10A flown on same profile for reference.

- Note 1: A-10A does not appear to have the same bug.

 

- Note 2: I noticed I could not get more than 83% N1 even at max throttle input, which is odd. Engines being anemic is one thing, but I know the TF-34 gets most of its thrust from the fan so I'll see if I can find some charts for N1/N2 speeds.

F5ThrustCheck.trk

A10ThrustCheck.trk

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Good work PetRock. Just a question, was this latest open beta patch?

Proud owner of:

PointCTRL VR : Finger Trackers for VR -- Real Simulator : FSSB R3L Force Sensing Stick. -- Deltasim : Force Sensor WH Slew Upgrade -- Mach3Ti Ring : Real Flown Mach 3 SR-71 Titanium, made into an amazing ring.

 

My Fathers Aviation Memoirs: 50 Years of Flying Fun - From Hunter to Spitfire and back again.

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@Nineline any idea what kind of priority this is given and when can we expect a fix?

I know this is kind of taboo to ask, but this is really a fundamental flaw.

 

Thanks

Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s

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  • ED Team
@Nineline any idea what kind of priority this is given and when can we expect a fix?

I know this is kind of taboo to ask, but this is really a fundamental flaw.

 

Thanks

 

I can't say when, but I know its actively being worked on. It is a big bug, so I think it will be addressed as fast as possible.

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  • 3 months later...
I can't say when, but I know its actively being worked on. It is a big bug, so I think it will be addressed as fast as possible.

 

Any news?

This and the engine bug are serious stuff, why aren't they fixing them?

Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s

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Just bumping this. Please ED prioritise serious known bugs like this

 

Bumping it isn't going to make ED work on the F-5's bugs any faster, or at all for that matter. Lot of people finding out the hard way what happens when their module isn't the new baby anymore. Expect nothing and be pleasantly surprised at the changelog when they finally get around to it.

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