[REPORTED] serious headwind/tailwind bug

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.

Sorry to say, but it is a common misconseption to think that his thoughts are a common misconseption. If the changes in aircrafts' heading during high wind weathers are "quick", wind MAKES a big difference, and is definitely a dangerous thing.

I suggest you to go flying (in real life I mean), and see and feel what I am stating here. Good tip: start your tests at higher altitudes!

Thanks for your initial posting regarding the bug, didn't notice this one since mostly I don't use strong winds in my missions. :thumbup:

Edit: I noticed that one of my postings was deleted, which contained some information regarding the F-18 discussion herein, so I will try again.

The bug posted by bbrz doesn't relate to Viggen and F-18, I just tried it out and it worked as expected (=fine).

Sorry to say, but it is a common misconseption to think that his thoughts are a common misconseption. If the changes in aircrafts' heading during high wind weathers are "quick", wind MAKES a big difference, and is definitely a dangerous thing.

I suggest you to go flying (in real life I mean), and see and feel what I am stating here. Good tip: start your tests at higher altitudes!

Bbrz is an experienced IRL pilot. And unfortunately you’re incorrect, Steady state wind has NO effect on the way an aircraft flies once it’s left the ground - apart from it’s obvious changes in ground track and ground speed.. There is no such thing as the “downwind turn stall”. All the aircraft cares about is how fast it’s moving through the air, It doesn’t care if the air it’s moving through is stationary or moving at 100mph, as long as it’s constant. And that has nothing to do with it’s ground speed, it does not care how the earth is moving below it.

Aircraft are NOT bound to the inertial reference frame of the earth, it’s understandable to think they are, because as pilots we care greatly about not hitting the earth or navigating to a certain parts of it. We also spend a lot of time watching aircraft from the inertial reference frame of earth. But once an aircraft is airborne it only cares about the inertial reference frame of the air that it’s flying through, that air could be doing any speed, and as long as it’s constant and smooth it makes No Difference to the way the aircraft flies, it does not alter its stall speed, it’s turning ability or it’s maximum climb rate. And the aircraft certainly cannot gain or lose airspeed out of nowhere by turning in steady state wind. Now as I’ve said, wind will greatly alter its ground track and ground speed. But that’s all.

You can fly an aircraft into a 100mph headwind at 100mph airspeed (ground speed of 0mph) and make a rapid 180 degree turn with no issues. You will not suddenly fall out of the sky.

I suggest you to go flying (in real life I mean), and see and feel what I am stating here.

That's a bad idea since it would only prove that you are exactly one of the victims of this common misconception.

I really don't understand why you are trying to suggest something you don't know anything about and you are apparently not even trying to understand.

This 'classic' (steady) wind problem has been discussed numerous times in DCS and countless other forums.

I think it's many mixing all weather experienced by aircraft into the one thing.

Like wind or high wind. Instead use the correct words. Wind shear, turbulence etc.

https://www.nationalgeographic.com/travel/features/what-is-turbulence-explained/

https://news.delta.com/3-ways-deltas-groundbreaking-turbulence-app-changing-way-we-fly

I really don't understand why you are trying to suggest something you don't know anything about and you are apparently not even trying to understand.

Thats a good statement :thumbup:

The point to think about was the word "quick" ...

Imagine: you fly with wind blowing on your nose, quickly turn the aircrafts' heading by 180° within - let's assume - 1 second (e.g. by using thrust vectoring). What is your speed "against" wind now, and where does the nose point to? What is your lift after the turn? What will happen?

bbrz: Hey pilot, NEVER I intended to suggest you something, you really don't have to believe me. But using imagination helps to get it.

As long as changes happen "slowly" (e.g. heading and pitch), which relates to most aircraft flying "fast" in relation to "low" wind speeds, or flying "before stall", everything is fine. This is the reason why most of us don't take notice of this effect. But if you fly a slow mover, with strong winds ... I again state my rule: be aware when doing "quick" changes!

That's all, and should answer your question about "don't know what you are trying to suggest something".

The "suggestion" - if so - is more about using imagination for a situation happening in RL seldomly and unlikely.

The energy in your postings is massive, but thats OK for me.

Again, thanks for posting this bug in DCS!

edit: sorry, I forgot to write: problem increases with increasing inertia in relation to aerodynamic forces ...

... you fly with wind blowing on your nose, quickly turn the aircrafts' heading by 180° within - let's assume - 1 second (e.g. by using thrust vectoring). What is your speed "against" wind now, and where does the nose point to?

...But if you fly a slow mover, with strong winds ... I again state my rule: be aware when doing "quick" changes!

Again, it doesn't matter. A goldfish in its goldfish bowl, which sits on the table in a Shinkansen, can change his direction in far less than a second and he will not be affected at all, despite the fact that he's moving along at 170kts.

 

As long as changes happen "slowly" (e.g. heading and pitch), which relates to most aircraft flying "fast" in relation to "low" wind speeds, or flying "before stall", everything is fine. This is the reason why most of us don't take notice of this effect. But if you fly a slow mover, with strong winds ... I again state my rule: be aware when doing "quick" changes!

Please stop with the word wind, the aircraft creates it's own "airspeed" and fly's around in that air "It's in it, there is no relation to wind, it's in that wind" Wind only affects an aircraft, or is felt by an aircraft in relationship to the ground. Once in the air, it's just air speed over the wings. There is no relation, only to navigation, only the airport wind sock has this relationship because it's fix to the ground. The aircraft can be affected by wind sheer and or turbulent air. This can be very bad when slow, landing etc.

Thats a good statement :thumbup:

 

The point to think about was the word "quick" ...

Imagine: you fly with wind blowing on your nose, quickly turn the aircrafts' heading by 180° within - let's assume - 1 second (e.g. by using thrust vectoring). What is your speed "against" wind now, and where does the nose point to? What is your lift after the turn? What will happen?

 

bbrz: Hey pilot, NEVER I intended to suggest you something, you really don't have to believe me. But using imagination helps to get it.

 

As long as changes happen "slowly" (e.g. heading and pitch), which relates to most aircraft flying "fast" in relation to "low" wind speeds, or flying "before stall", everything is fine. This is the reason why most of us don't take notice of this effect. But if you fly a slow mover, with strong winds ... I again state my rule: be aware when doing "quick" changes!

 

That's all, and should answer your question about "don't know what you are trying to suggest something".

The "suggestion" - if so - is more about using imagination for a situation happening in RL seldomly and unlikely.

 

The energy in your postings is massive, but thats OK for me.

Again, thanks for posting this bug in DCS!

 

edit: sorry, I forgot to write: problem increases with increasing inertia in relation to aerodynamic forces ...

My job is to test and fly the imaginative or "a situation happening in RL seldomly and unlikely", as you put it, all day long IRL. And I will just say this, the results you state here in your "rule" are just that, imaginative and unreal. The only difference in strong steady winds and low speed are when you care about your location/attitude in relation to the ground. This is when wind does become a problem and certain limitations are put on max allowable crosswind component, take-off performance, landings, fuel consumption, ETA, etc, etc... Otherwise neither you or the aircraft cares about any direction or speed of steady wind. So IRL flight test data confirms what bbrz is saying and does not support your suggestion or theoretical results. Again, bbrz is talking about any flight condition WITHOUT reference to the ground <- this is important.

Again, bbrz is talking about any flight condition WITHOUT reference to the ground <- this is important.

Thanks pbishop for your input! I think you are following my thoughts a bit more than bbrz, but thats fine!

Yes, it seems I didn't consider this aspect too much for separating my statement from the bug-story, which in turn - especially in regards to the mentioned bug he noticed - would have been an important one.

Moving away from the bug-story again a bit:

I asked 4 pilots, including ones that fly sailplanes, motorplanes, jets, ... no matter which aircraft, all are saying the same, including me after 20 years of flying.

The bigger problem - unfortunately - is to find an english phraseology to make my thoughts "solid" and understandable, and not confusing too much. :P

Ask pilots: Nose into wind, or nose away from wind?

All pilots (still alive) would say: Nose into wind. Why? If you turn away too quick, your ground speed (and thus kinetic energy) must re-build in order to have the airspeed which you need a few second later after your turn away from wind. Easy to perform in a motorplane, hard to perform in a sailplane. If this is a phraseology you understand better, I would be happy, if not ... my world would not crash immediately :smilewink:

If the difference in energy is high: you are in trouble. If the difference in energy is low: you are fine and would most probably not notice the effect.

More complex things come up when "post stall" flying is the topic. If you pitch a vectorized vehicle like one of the new MiGs about 180° while the aircraft is still flying more or less "straight ahead" due to its inertia, the trailing edge would then be hit by airflow, ... so what is your lift then? How long would it take to accelerate it to have enough airflow again when wind is blowing strongly now from behind (but steady!)?

Its was ment more in this direction ... so ...

I asked 4 pilots, including ones that fly sailplanes, motorplanes, jets, ... no matter which aircraft, all are saying the same, including me after 20 years of flying.

Sorry to say, but if you are a real pilot since 20 years and you (still) believe that wind affects the aerodynamics/performance your lack of knowledge is shocking.

You are really lucky that you didn't run into serious problems until now!

Sorry to say, but if you are a real pilot since 20 years and you (still) believe that wind affects the aerodynamics/performance your lack of knowledge is shocking. You are really lucky that you didn't run into serious problems until now!

Yes, I am :) I was born on a Sunday. :thumbup:

But furtunately, thats not 100% true.

Anyway you can try out: fly a circle pattern (best would be a sailplane) without pushing or pulling stick, in wind conditions, and non-wind conditions. Once the nose turns into wind, without pulling or pushing the stick (!) the nose would come up. If the nose turns away from wind, without moving the stick, the nose would come down. It is not necessary that you believe me, but thats the observation nearly all pilots I know have made.

Before stating my knowledge is shoking (I don't think so), I invite you (not suggest you ... !) to try this out whenever you find a chance to do so! It makes sense to start with 20° of bank, and increase as long as the aircraft can handle it (60° is a good value, and most sailplanes are allowed to do so).

If you live in Europe, you might wann visit me, and we go for a ride. What would you say?

If you live in Europe, you might wann visit me, and we go for a ride. What would you say?

I do live in Europe, but flying with you sounds like a rather dangerous idea.

FYI, I was flying gliders for many years in the Alps and for a few years I even owned 1/3 of glider.

Strangely, I never observed anything like you and 'nearly' all pilots you know did.

Btw, if your theory is correct, why don't all pilots you know confirm your observation?

That fishbowl on the Shinkansen analogy was a nice one, I'll make sure to use that when explaining this one day.

And TOViper, what these other guys are saying is correct. If you're in a steady state wind, your maneuvers will be the same as in still air.

Brgds, another RL pilot.

That fishbowl on the Shinkansen analogy was a nice one, I'll make sure to use that when explaining this one day.

An old ex WWII pilot instructor explained it to me that way (although not with the Shinkansen) when I made my glider pilots license many many decades ago.

IMO still the best and easiest explanation, but obviously it doesn't always work ;)

An old ex WWII pilot instructor explained it to me that way (although not with the Shinkansen) when I made my glider pilots license many many decades ago.

IMO still the best and easiest explanation, but obviously it doesn't always work ;)

Yea it explains the concept very well.

People always think of wind the way we feel it on the ground, like something "flowing" in a stream.

It always creates the "aha" moment, when you understand that it's just one big airmass moving, and you only feel it because you are stuck to the ground.

Another way of thinking about it, is to remove the ground all together.

You're flying at 10,000 feet, above a total overcast layer, so you can't see the ground anymore. The clouds are in the same airmass as you, and you don't have a groundspeed readout.

In this scenario, you could not feel any difference in wind speed, be it 0 or 1000 kts (as long as it's nice an laminar). You and the clouds would be in the same airmass.

If the opposite was true, I think ATC would be apprehensive about vectoring me next time I was in 150kt winds at 40,000' :p

TOViper, been flying for about 20 years here too, sorry to say but you are simply wrong. I'm shocked to hear you believe that and I honestly hope you lied about flying IRL, or else pick-up the PPL ground training level 1 and read it again.

I've had a student once that wanted to stall the aircraft after turning downwind because he was caught off-guard by the higher groundspeed, as well as somebody who had a tendency (this is much more common) to overspeed the aircraft when on a windy final, all becuase they get "impressed" by the ground references moving too fast / too slow compared to what they got used to when flying in no wind.

I understand you might get the feelign that your airspeed changes, but that's just your eyes and ground references messign with your senses. Look at your instruments, there's only 1 thing that matters: AIR SPEED. I have yet to see any aircraft where the stall speed and VNE are given in GS ;)

I do live in Europe, but flying with you sounds like a rather dangerous idea. Btw, if your theory is correct, why don't all pilots you know confirm your observation?

If you have glider license, why not going flying?

What if I would hand over controls to you? Would you then feel better? :)

Pilots which I can talk to confirm these observations independently, and other "pilots" (which I cannot talk to) in the forum cannot confirm them.

Difficult story ... so what should we do in that case? Is that a comms problem? Have they all forgotten something, done something they didn't notice/remember?

There are "truths" around, and I rely (not only) on observations and think about what is more safe: turn away or turn into wind. There is only one answer which leads to the more safe solution: into wind, of course thinking about all other aspects like landing, take-off, all things you mentioned before.

BTW: wind in english language is obviously the one that is related to weather. "Wind" in my language is often used to describe airflow too, which makes the whole story much more difficult for you poor readers :)

I understood all you stated guys, really I did, and it is impressive to read all your postings, and I understand what I want to tell, but did you understand what I wanted to tell you ... ?

Sender <> Receiver problem, induced by Sender? :helpsmilie: Damn, I think I f..... THIS one up.

Back to "post stall" ... BUT STOP, this is a bit OT I think.

Why? If you turn away too quick, your ground speed (and thus kinetic energy) must re-build in order to have the airspeed which you need a few second later after your turn away from wind.

No. Just no. That is not how it works. Your kinetic energy is relative to the air the aircraft is flying through NOT the ground.

If you are flying along at 100mph airspeed into a 100mph wind your ground speed would be 0mph, but the aircrafts energy state would be 100mph. If you pull to the vertical from that 0mph ground speed situation you will be going upwards vertically at 100mph. If you do the same manoeuvre while starting off flying downwind, airspeed still 100mph, with a ground speed of 200mph you will still only go vertically upwards at 100mph, not 200mph.

The only time an aircrafts energy state is relevant to the ground is when it’s interacting with the ground, so takeoff or landing.

Thanks pbishop for your input! I think you are following my thoughts a bit more than bbrz, but thats fine!

 

More complex things come up when "post stall" flying is the topic. If you pitch a vectorized vehicle like one of the new MiGs about 180° while the aircraft is still flying more or less "straight ahead" due to its inertia, the trailing edge would then be hit by airflow, ... so what is your lift then? How long would it take to accelerate it to have enough airflow again when wind is blowing strongly now from behind (but steady!)?

 

Its was ment more in this direction ... so ...

Either you are talking about something completely different or you don't know what you are talking about at all. Either way.... good luck!

Cheers

pbishop, I think you are on the right corner with me, and also deano87 I think.

What might not came out clearly I think was the word "quick" changes.

When doing "quick" changes, this normally means to use energy in order to initiate and hold a turn, loop, whatever. During this time the aircraft will loose energy, in fact dissipating kinetic or potential energy into heat. The energy level (if not "filled" up again e.g. by using increased power if an engine is installed) will decrease. So either less altitude or less airspeed is the result (THIS is what I stated as dangerous).

I still cannot bring evidence right now about the story about increasing and decreasing speed in a constant bank turn within a glider at high wind conditions, which - after seeing all your arguments and postings and my knowledge - makes me crazy. There must be perception issues, or the weather was not that "constant" as seen, or something else I don't know. I have to talk once more to (meanwhile five guys which supported my own experiences with their own ones), and clearly ask about which parameters have been held constant and which changed.

This relates to the "post-stall" story as well. If the MiG is doing a Cobra, much of its kinetic energy is dissipated within 3 seconds. So if it would go for a 180° turn using all its flight controls including thrust vectoring, the aircraft will need power or height to get back to its initial airspeed.

I have to read my postings again tomorrow, and see if I disregarded any of your information, or if you just missed parts of my thoughts due to my bad English or I simply left out something.

I have to sort this out a bit, but I FULLY understand if you guys pull the eject handle on this ... :D

Thank you anyway for taking the time!

pbishop, I think you are on the right corner with me, and also deano87 I think.

 

What might not came out clearly I think was the word "quick" changes.

When doing "quick" changes, this normally means to use energy in order to initiate and hold a turn, loop, whatever. During this time the aircraft will loose energy, in fact dissipating kinetic or potential energy into heat. The energy level (if not "filled" up again e.g. by using increased power if an engine is installed) will decrease. So either less altitude or less airspeed is the result (THIS is what I stated as dangerous).

 

I still cannot bring evidence right now about the story about increasing and decreasing speed in a constant bank turn within a glider at high wind conditions, which - after seeing all your arguments and postings and my knowledge - makes me crazy. There must be perception issues, or the weather was not that "constant" as seen, or something else I don't know. I have to talk once more to (meanwhile five guys which supported my own experiences with their own ones), and clearly ask about which parameters have been held constant and which changed.

 

This relates to the "post-stall" story as well. If the MiG is doing a Cobra, much of its kinetic energy is dissipated within 3 seconds. So if it would go for a 180° turn using all its flight controls including thrust vectoring, the aircraft will need power or height to get back to its initial airspeed.

 

I have to read my postings again tomorrow, and see if I disregarded any of your information, or if you just missed parts of my thoughts due to my bad English or I simply left out something.

I have to sort this out a bit, but I FULLY understand if you guys pull the eject handle on this ... :D

 

Thank you anyway for taking the time!

Regarding your quick turns with thrust vectoring etc. Yes of course the aircraft decreases in airspeed and requires more energy. But that is not effected by steady state wind in any way. If the a Sukhoi does a Cobra in perfectly still wind, or a 30knot wind or a 200knot wind, the aircrafts energy state at the end of all of those different scenarios will be the same. It should end up with the same Airspeed, in all 3 cases the ground speed will be different, but the energy state of the aircraft, IE it’s ability to turn, or climb will be the same in all 3 cases. Doing a quick turn downwind is no more dangerous then doing it in perfectly calm wind. Providing that we are talking about steady state wind conditions.. obviously the higher the wind speed (usually) the high the possible gust change, which of course can result in sudden wind shear. But this is Not what we are talking about here.

In cases of the 5 pilots talking about pitching up when turning into wind... I don’t know what to tell you, but they are wrong, there is no physical way this can happen under steady state wind conditions. Where does that energy come from? It’s not like the aircraft wasn’t being blown downwind at the same speed when it was flying crosswind 90 degrees earlier in the turn... as long as the wind speed hasn’t changed then there is no energy addition or loss to the system = No increase or decrease in airspeed = pitch up or dive when turning into or down wind.