no evidence The wobbly flight model

[Pilum]

While not directly coupled to the F-18, I just happened to have dusted off this module to do some drogue refueling training which can be fun sometimes.

However, the wobbly flight model bugs me. Sure, it’s not just the F-18. It’s something that DCS has across the board as most FM’s in DCS, be they a Bf-109, Spitfire or F-18 has this property.

TBH, I find this an irritating aspect of the current “state-of- the art” flight sims (it’s not just DCS), since it seems to be the norm, and you can find it in others like Il-2 Sturmovik as well.

Maybe initially it was a reaction to the so-called “on-rails” FM’s that many of the very earliest sims suffered from, and led to the rise of the wobbly FM’s that I remember were initially greeted with such enthusiasm by some customers who seemed think that the more difficult it was to fly, the more realistic it must be.

However, if you take a look at the attached videos (you can find many like them), you will see that the “on-rails” FM is actually more realistic. There is virtually none of the wobbliness we have in-game, and there is a more direct response and ending to the stick input both in terms of a direct response and a direct termination of movement which makes it much easier to avoid the PIO’s that are inherent in current flight sims.

So my question is this: Is this just an adaptation to what the customers wants, as in wobbly means more realistic and sells better, or is it an actual limitation in the simulation engine, as in the way it’s implemented leads to the wobbliness and there is nothing they can do about it?

Again, the F-18 is not the only culprit, but since this seems to be one of the more active DCS forums maybe some of the forum members here have an answer this question?

Is the in-game flight model wobbliness there by choice, or is it a result of a game engine limitation?

Note in the first video how the canopy moves in relation to the clouds on the horizon as he gets close to the basket: The pilot is continuously doing minute corrections with no wobbliness and no PIO indications at all. He is literally “chasing the basket” which is a big no-no in-game because you’ll end up in PIO’s.

F-18 drogue refueling in turbulence

F-18 doing minute corrections to hook-up and stay in the groove

Crisp and wobbly free Yak-3 rolling and flying

Edited December 2, 2024 by Pilum

[BIGNEWY]

Hi, 

please include a track replay example of what you are seeing, short tracks are best. 

If you have any evidence that something is wrong please also include that. 

Regarding air refuelling, it is certainly challenging in DCS, and we are planning better basket physics which will help with contact. 

thank you 

[Phantom711]

I don‘t think there‘s anything „wobbly“ about the flight physics in DCS.

There are also a lot of variables that your post doesn‘t take into account. Namely the stick the player is using, curve settings and the player’s skill level. 
Also the posted videos don’t really prove your point. A real pilot is simply better at not getting into PIOs than most players (at a beginner level). The trick is simply to already plan a counteraction to your own input and then execute it timely. TBH my AAR in DCS doesn‘t look much worse than what is shown in those RL videos.

[BIGNEWY]

Just now, Phantom711 said:

TBH my AAR in DCS doesn‘t look much worse than what is shown in those RL videos

you havn't seen my attempts  

[Phantom711]

vor 8 Minuten schrieb BIGNEWY:

you havn't seen my attempts

Leaves room for speculation: Yours could look much worse or absolutely stellar….

[Pilum]

1 hour ago, BIGNEWY said:

Hi, 

please include a track replay example of what you are seeing, short tracks are best. 

If you have any evidence that something is wrong please also include that. 

Regarding air refuelling, it is certainly challenging in DCS, and we are planning better basket physics which will help with contact. 

thank you 

What? Are you REALLY questioning this? You mean you ACTUALLY cannot see the difference between the videos I posted and how it works in game?

Just do an in-game tanker setup with the F-18, approach the basket and then try to chase it like they did in the two IRL drogue videos I posted and see what happens: You get massive PIO's.

This is why every DCS tanker instruction video I have seen stresses the fact that you NEVER chase the drogue BECAUSE you get PIO's. This is why they're all adamant you have to approach it super careful basically in a straight line. Any late adjustments like we see in the IRL tanker videos I posted are doomed to fail.

So to reiterate my point: You CANNOT make the same type of small adjustments late when up close to the basket in-game.

Again, my question is more if it (the wobbly FM) is by design or a limitation in the simulation engine.

Edited December 2, 2024 by Pilum

[BIGNEWY]

Please include a track replay example. 

thank you 

[Phantom711]

vor 2 Minuten schrieb Pilum:

Just do an in-game tanker setup with the F-18, approach the basket and then try to chase it like they did in the two IRL drogue videos I posted and see what happens: You get massive PIO's.

How can you tell from the video, that they were „chasing the basket“? You don‘t see the stick inputs. Again, a home PC sim can not be 100% like the real jet due to limitations I already mentioned. Simply the fact, that most „joysticks“ have a shorter lever than the RL Hornet stick makes minute inputs harder to achieve. You can adjust the curves to mitigate that though.

What stick are you using?

[Phantom711]

Maybe you also misunderstand the phrase, when people advise „not to chase the basket“. It simply means, that you should not have your eyes glued to the basket but rather see the whole picture and just take quick glances at it. Of course you still can/have to make corrections in order to get your probe aligned with the basket.

[Nealius]

The only wobbliness I've noticed in the Hornet is the nose having some weird adverse yaw tendencies and lateral oscilations when making hard maneuvers, that other jets like the Viper and even Tomcat don't. 

[Pilum]

Guys, I’m a retired aeronautical engineer with Masters in Aerodynamics and I’m also a pilot. But no, not a qualified F-18 pilot, if you want to disqualify me on that point. But I’ve flown everything from gliders to Pitts S-2’s etc. so I would say I’m not totally in the dark about flight mechanics, how aircraft behave, and PIO’s etc.

TBH, I can’t tell if those who have responded so far in this thread really can’t see the difference, or are just being obtuse after spending hundreds of hours mastering the in-game FM’s and maybe for that reason want to believe that the current FM’s are as real as it gets.

Look: I’m not saying it cannot be done: I do it myself in-game. I have a Hall-sensor Thrustmaster stick with an extension and have done it both with linear or S-curve settings. This is not the problem. What I'm saying is the problem, is that due to the wobbly FM's that’s seems to be inherent in the DCS modules, this means that you have to use the careful line-up and basically fly straight in method.

And BIGNEWY: Here you go, here are some track videos:

And like this one says: Never chase the basket as in trying to do last moment adjustment: https://youtu.be/tVJH_o3KmOk?t=229

https://youtu.be/FP74D4gCK_U?t=151

https://youtu.be/PX7nsYA_K-o?t=233

 

Now watch those videos and compare that to the two F-18 tanker videos I posted in the OP.

Do the aircraft's in-game and IRL behavior look the same to you? Really?

IRL, the pilot is inputting small, precise, last second adjustments with no tendencies to PIO whatsoever.

Edited December 2, 2024 by Pilum

[MARLAN_]

Seems fine to me.

 

 

[Pilum]

34 minutes ago, MARLAN_ said:

Seems fine to me.

 

 

First point: Notice that whoever is flying is in a perfect position. The basked is literally released right onto the probe. This DCS pilot is perfectly aligned both sideways and in height. All that is required is to move forward a few meters. Now why is that? Can we suspect that whoever did this video has done it before? The answer to this rhetorical question is of course yes.

And when it comes to airplanes, you can master flying basically anything. All it takes is practice. And this is something gamers love and I can understand all that: It's nice to finally master something that requires a lot of practice. But the question here is realism. Is it realistic? And the answer is no. Because a plane like this would never be accepted into service. It would probably land at 6-7 on the Cooper-Harper scale. Probably a 7 because you would not be able to chase a basket that is affected by turbulence without getting into PIO's.

This bring us to the second point: Notice that the basket in DCS is always perfectly stabilized? If you are perfectly aligned you can drive straight in. In fact, that's the way one of the DCS training videos I posted above showed: The recommendation was never to try to adjust, but to line up perfect straight behind and then go back and forth until hookup. 

Problem is that that is not how it works IRL: IRL the basket moves and you need to feed in small inputs, and you actually chase the basket.

So I post this yet again: Notice the small precise movements the aircraft makes with no tendency to PIO? In fact, it looks a bit like he is flying an "on-rails" FM. Imagine that.....

F-18 drogue refueling in turbulence

Edited December 2, 2024 by Pilum

[MARLAN_]

2 minutes ago, Pilum said:

First point: Notice that whoever is flying is in a perfect position. The basked is literally released right onto the probe. This DCS pilot is perfectly aligned both sideways and in height. All that is required is to move forward a few meters. Now why is that? Can we suspect that whoever did this video has done it before? The answer to this rhetorical question is of course yes.

And when it comes to airplanes, you can master flying basically anything. All it takes is practice. And this is something gamers love and I can understand all that: It's nice to finally master something that requires a lot of practice. But the question here is realism. Is it realistic? And the answer is no. Because a plane like this would never be accepted into service. It would probably land at 6-7 on the Cooper-Harper scale. probably a 7 because you would not be able to chase a basket that is affected by turbulence without getting into PIO's.

This bring us to the second point: Notice that the basket in DCS is always perfectly stabilized? If you are perfectly aligned you can drive straight in. In fact, that's the way one of the DCS training videos I posted above showed: The recommendation was never to try to adjust, but to line up perfect straight behind and then go back and forth until hookup. 

Problem is that that is not how it works IRL: IRL the basket moves and you need to feed in small inputs, and you actually chase the basket.

So I post this yet again: Notice the small precise movements the aircraft makes with no tendency to PIO? In fact, it looks a bit like he is flying an "on-rails" FM. Imagine that.....

F-18 drogue refueling in turbulence

What are you even talking about...

I didn't magically appear perfectly behind the basket, I moved there. My flight is stable because I am in control of the aircraft.

"Notice the small precise movements the aircraft makes with no tendency to PIO" ... You mean exactly what I just demonstrated?

---

Obviously the basket needs physics added (and needs to be deployed prior to pre-contact...) and wake turbulence and wind simulation needs improvement but none of these have anything to do with the F-18.

[Pilum]

7 minutes ago, MARLAN_ said:

What are you even talking about...

I didn't magically appear perfectly behind the basket, I moved there. My flight is stable because I am in control of the aircraft.

"Notice the small precise movements the aircraft makes with no tendency to PIO" ... You mean exactly what I just demonstrated?

---

Obviously the basket needs physics added (and needs to be deployed prior to pre-contact...) and wake turbulence and wind simulation needs improvement but none of these have anything to do with the F-18.

Yes, you flew into the exact right position for catching the basket and you were in perfect control of your aircraft. Which is a result of enough training on the in-game FM.

However, as I said, you can with practice learn to fly basically anything, and your video is a perfect example of that. However, that does not mean an aircraft has acceptable, or in this case realistic behavior.

So no, what you demonstrated was instead exactly my point: To hook up, in DCS you basically need to fly super smooth and straight in. Notice that both your airplane and the drogue are almost perfectly stabilized in-game. Now compare that to the way the pilot in the video I posted is battling to hook up and the rapid changes just before he catches the basket?

Sorry, but if you can't grasp the difference in aircraft behavior between these two videos then I can't help you.

[Razor18]

2 minutes ago, Pilum said:

Yes, you flew into the exact right position for catching the basket and you were in perfect control of your aircraft. Which is a result of enough training on the in-game FM.

However, as I said, you can with practice learn to fly basically anything, and your video is a perfect example of that. However, that does not mean an aircraft has acceptable, or in this case realistic behavior.

So no, what you demonstrated was instead exactly my point: To hook up, in DCS you basically need to fly super smooth and straight in. Notice that both your airplane and the drogue are almost perfectly stabilized in-game. Now compare that to the way the pilot in the video I posted is battling to hook up and the rapid changes just before he catches the basket?

Sorry, but if you can't grasp the difference in aircraft behavior between these two videos then I can't help you.

Yeah, at some point in time, F-18 FM (maybe others too) got a bit more sensitive. But it only means more practice, or if you don't have the patience to adjust to the new flight model, I would recommend to put in a Curvature of 20 for both the pitch and the roll axis. This brings back just about the old sensitivity you got probably used to. Also, PIO usually comes from looking at the basket in close, and not looking on the big picture (including looking at the FPM to keep level flight) to keep you from chasing the basket vertically.

[SharpeXB]

Honestly in the real life footage it looks harder than DCS (I’m sure it is)

I only have PC flying experience but to me the Hornet is just a very easy sim plane to fly. Not like a warbird or helicopter “wobbly” is not what comes to mind.

This isn’t real life, it’s a game. Imagine driving your car on a computer screen with a plastic Xbox controller and no force feedback. You can’t get any physical feedback like you can from a real car or airplane, the only sensory input you get is your vision. I mentioned in that video I find it like learning to ride a bicycle using only your eyes. 
In fact being a real pilot is probably almost distracting or detrimental if that makes any sense. I think most real pilots comment on the fact that they simply can’t feel the aircraft like they would IRL. It’s like asking me if the BMW in a racing sim feels like the real one I’m driving. That question really has no answer.

[Phantom711]

So…I (we) just had a quick chat with 2 RL pilots. One of them Super Hornet, the other Legacy and Super Hornet.

Now both of them haven‘t touched DCS in a while, but from what they know, the FM of the Hornet might not be perfect, but it’s fine.

Interestingly, they also mentioned that certain types of „missions“ or parts thereof are not even practiced in the real life military simulator because it lacks too much of that „pants in seat“ feeling (feedback) that one would have in the real jet and that you need for that kind of nuanced flight. AAR is one of those things.

[MARLAN_]

4 minutes ago, Pilum said:

Yes, you flew into the exact right position for catching the basket and you were in perfect control of your aircraft. Which is a result of enough training on the in-game FM.

However, as I said, you can with practice learn to fly basically anything, and your video is a perfect example of that. However, that does not mean an aircraft has acceptable, or in this case realistic behavior.

So no, what you demonstrated was instead exactly my point: To hook up, in DCS you basically need to fly super smooth and straight in. Notice that both your airplane and the drogue are almost perfectly stabilized in-game. Now compare that to the way the pilot in the video I posted is battling to hook up and the rapid changes just before he catches the basket?

Sorry, but if you can't grasp the difference in aircraft behavior between these two videos then I can't help you.

The pilot in the video is flying perfectly once he's hooked up. He only "battles" initially because the basket is moving in the wind/turbulence. Again, nothing to do with the F-18, those are core game issues.

And as mentioned, the sim FM isn't going to be *perfect* to real life but it is very close. It's one of the things ED has done very well.

[SharpeXB]

5 minutes ago, Razor18 said:

Yeah, at some point in time, F-18 FM (maybe others too) got a bit more sensitive. But it only means more practice, or if you don't have the patience to adjust to the new flight model

What’s funny is when I tried the new FM I found it so easy I thought something was broken. Seriously, I went into the settings to see if some easy mode had been enabled. I was being shot at by SAMs and texting on my phone while AARing and just could do it in my sleep

Really I had just taken an AH-64 hiatus having never played helicopters. Wow what a wake up. After that doing AAR is easy! (might be a worthwhile tip there)

[HILOK]

5 hours ago, Pilum said:

While not directly coupled to the F-18, I just happened to have dusted off this module to do some drogue refueling training which can be fun sometimes.

However, the wobbly flight model bugs me. Sure, it’s not just the F-18. It’s something that DCS has across the board as most FM’s in DCS, be they a Bf-109, Spitfire or F-18 has this property.

TBH, I find this an irritating aspect of the current “state-of- the art” flight sims (it’s not just DCS), since it seems to be the norm, and you can find it in others like Il-2 Sturmovik as well.

Maybe initially it was a reaction to the so-called “on-rails” FM’s that many of the very earliest sims suffered from, and led to the rise of the wobbly FM’s that I remember were initially greeted with such enthusiasm by some customers who seemed think that the more difficult it was to fly, the more realistic it must be.

However, if you take a look at the attached videos (you can find many like them), you will see that the “on-rails” FM is actually more realistic. There is virtually none of the wobbliness we have in-game, and there is a more direct response and ending to the stick input both in terms of a direct response and a direct termination of movement which makes it much easier to avoid the PIO’s that are inherent in current flight sims.

So my question is this: Is this just an adaptation to what the customers wants, as in wobbly means more realistic and sells better, or is it an actual limitation in the simulation engine, as in the way it’s implemented leads to the wobbliness and there is nothing they can do about it?

Again, the F-18 is not the only culprit, but since this seems to be one of the more active DCS forums maybe some of the forum members here have an answer this question?

Is the in-game flight model wobbliness there by choice, or is it a result of a game engine limitation?

thanks for the initiative. exactly my observations!

my assumption is that atmospheric effects aren't simulated, therefore a FM matching real a/c dynamics would indeed appear to be on rails. that's why they have to make it a tad inherently unstable. this is also noticeable in approved professional flight training sims up to FFS-grade (the moving ones). they're usually much more finicky on the pitch axis than the real plane.
one thing i find all DCS airplanes have in common is yaw dampening seems a bit weak, or wobbly.

the OP as i take it only mentioned AAR as an example, but is talking about the DCS FM in general, so maybe more constructive not to focus on the refueling aspect of FMs.

[Pilum]

3 minutes ago, Razor18 said:

Yeah, at some point in time, F-18 FM (maybe others too) got a bit more sensitive. But it only means more practice, or if you don't have the patience to adjust to the new flight model, I would recommend to put in a Curvature of 20 for both the pitch and the roll axis. This brings back just about the old sensitivity you got probably used to. Also, PIO usually comes from looking at the basket in close, and not looking on the big picture (including looking at the FPM to keep level flight) to keep you from chasing the basket vertically.

Look, I'm not saying it can't be done. I actually do it myself from time to time. I think the F-18 is a great module and I like doing the carrier T/O and landings as well.

However, my point is that the in-game DCS FM is wobbly in that its easy to get into PIO's, and that this is not realistic, and that the IRL videos I posted shows that. That is all.

Just to reiterate: Take a look at how the Growler pilot catches the basket by small precise movements in the turbulence: Use the canopy rim and the horizon as a reference to see just how precise and controlled these movements are IRL. I would love to see an in-game video tanker video with an F-18 replicating that. However, since we don't have turbulence yet exactly that scenario is of course impossible to reproduce. However, I've yet to see an in-game video where a pilot is off in height and angle and rapidly gets lined up again and catches the basket in the same crisp way as it is done IRL.

[Vakarian]

You seem to be forgetting that in the sim you don't have cues you would get from the real aircraft so you can only react to the visual cues (and be proactive as you should know to expect). That's a reason why it's so much easier to get into the PIO in the sim than it is IRL. You said that you are a IRL pilot so you should be aware of that. On the other hand, as the others have demonstrated here it can be mitigated through a lot of practice. In other words, it's really nothing else than (gaming) skill issue. From all your human sensors, you are reduced to only one when flying in the sim, ofc it's going to be harder.

[Phantom711]

@Vakarian

Yes…but this is a DCS forum where even my answer referencing 2 RL F/A-18 pilots is not enough evidence…

[Pilum]

7 minutes ago, HILOK said:

thanks for the initiative. exactly my observations!

my assumption is that atmospheric effects aren't simulated, therefore a FM matching real a/c dynamics would indeed appear to be on rails. that's why they have to make it a tad inherently unstable. this is also noticeable in approved professional flight training sims up to FFS-grade (the moving ones). they're usually much more finicky on the pitch axis than the real plane.
one thing i find all DCS airplanes have in common is yaw dampening seems a bit weak, or wobbly.

the OP as i take it only mentioned AAR as an example, but is talking about the DCS FM in general, so maybe more constructive not to focus on the refueling aspect of FMs.

Yes, but what's happening here now never seems to fail: I've seen this also in WW1 & WW2 sim forums: People spend hundreds, if not thousands of hours mastering these in-game FM's and I can understand that with so much invested, you don't want to hear that what you are flying is unrealistic.

In WW2 sims, you see people with full flaps, gear out, in hard slow-speed maneuvering pulling stunts defying flight mechanics because the in-game FM allows them to do that and they have mastered the art, which sadly is not mastering the IRL art, but is in this case becoming aces of the FM's the developers give them, nothing else.

I started this off with a genuine question, because state-of-the-art FM's in many cases exhibit this wobbly behavior. You can see it in WW1 & WWs sims as well. And what I wanted to see was if someone here could shed a light on this in DCS and why we have the wobble we have. But now I fear this will devolve into an avalanche of simmers lining up to tell us just how realistic this sim really is, which is not very helpful at all in answering the original question......