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Upcoming flight model adjustments


Diesel_Thunder

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Maybe it's more that the heart does not need to pump so hard, because the brain is located in a lower location in a reclined seat. Combined with the lifted legs it is very plausible that it helps against GLOCs. Also I would think the engineers did enough research to confirm the advantages of the reclined seat.

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12 minutes ago, feipan said:

Also I would think the engineers did enough research to confirm the advantages of the reclined seat.

Read the F-16 Program Manager's words from four posts back. :thumbup:

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The new flight model won't change the peak STR much, however the energy bleed rate is much more realistic and making the jet very energy efficient.

That's what I keep repeating: if the FM has wrong drag profile and you try to compensate for it with a wrong thrust profile, you may end up with an accurate peak STR but inaccurate energy bleed rate and acceleration. People has verified it with tacview. In hard pull the energy bleed rate (negative ps) is almost twice as much as the flight manual shows. The FM update is a valid fix.

I still remember how USAF measures a jet's agility: pull hard to turn 180, and accelerate back to the initial speed. Use the total time as agility metric. 

https://ntrs.nasa.gov/api/citations/19960041232/downloads/19960041232.pdf

In reality, F-16's agility metric is way better than any 4th gen fighters because it turns fast and loses little speed, however that may not be the case in current DCS.

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2 hours ago, TheBigTatanka said:

To be fair, when we (our virtual squadron) flies BFM, we turn off G effects. No need to have distractions when you are trying to teach aspect angles, range cues, and turn circles.

Sent from my Pixel 3 XL using Tapatalk
 

Really sustaining the correct G isn't part of BFM?

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No longer will i need the 2gb folder on my desktop of F-16 viper test sheets to rant on endlessly to my friends about the vipers supposedly underperforming in dcs haha.

Video looks pretty good, what it looks like, and what i hope, is it will reach rated STRs at MIL power as well, now that the drag values have been changed. finally giving the impression that we are flying a big mouth viper.

 

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A brief explanation why the energy efficiency is so important in 2C fight even though the peak STR is not changed much:

This is a schematic of conventional 2C fight turning cycle. The trajectory can be divided into 3 phases:

1) hard pull, depletes energy, and turn radius decreases.

2) light pull, energy increases, turn radius widened.

3) straight line acceleration.

The FM tweak lessens energy cost in phase 1), and increases the energy gain in phase 2) and 3), making the energy balanced, or even increased in each 2C turning cycle. Check the first dogfight in GS's video (F-16 vs F/A-18), the speed at the end of the first 2C turning cycle is almost 530 knots and he has to reduce throttle to avoid over-speeding. 

In the past the drag profile was wrong and it was compensated by thrust, the peak STR is close to true value but the energy depletion in hard pull is doubled or even tripled in some cases, and struggles to regain energy in light pull, leaving the F-16 far from a balanced energy usage.

schematic_2C_fight.png


Edited by karasawa
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On 3/9/2022 at 5:19 PM, Diesel_Thunder said:

Surprised this hadn't been posted yet. :blink:

 

Can't wait to fly this in the next patch!

 

Remark: At 3:14 where the F-16 beats the <profanity> out of the F-18, the F-16 didn't even use the afterburner.

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Looks like the salt is already flowing before the Viper finally gets its FM update.  DCS is a sim.  We don't care about balance.

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On 3/10/2022 at 3:38 PM, Glide said:

Sure, but I can hear the smile on his face as he's flying it. 

Yeah, me too.

And GS for sure is competent in judging flight models - and I don't mean "true to reality", but "feels right compared to other virtual aircraft".

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"Muß ich denn jedes Mal, wenn ich sauge oder saugblase den Schlauchstecker in die Schlauchnut schieben?"

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vor 8 Stunden schrieb Hiob:

Yeah, me too.

And GS for sure is competent in judging flight models - and I don't mean "true to reality", but "feels right compared to other virtual aircraft".

Each one of these two circle fights would have killed him in a fight involving heaters.

What I saw after the video is a consiberably lower AOA compared to what we have now at the same speed, same weight in the general area below 250kts and that's where it is most noticable. And where the current Viper falls short. It'll rock for sure, and more closely match publically available data.

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On 3/10/2022 at 4:14 AM, Snappy said:

Didn’t ED always claim the sustained turn rates were already spot on, matching the data they used to model it?

Now given the first side by side comparison in the video it seems they further boosted STR significantly.

Certainly hope they re not catering to the complaining crowds, it seems to become a recurring scheme lately.

 

 

Read this yourself. This is from ED. The F-16 is still under-performing at many altitudes. Is the error small by your standard?

image.png

It is under-performing. There is still 4%-5% error and that sometimes means whether the F-16 comes out victory or victim.


Edited by karasawa
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...why do I have the sneaking suspicion that it was a perfect clever move by ED letting GS relase a teaser video and see what the upcoming discussions about the new FM are gonna be....

I really dont know if you can call it complaining about the F16s FM when the outcome of dogfights in the F16 differ drastically from the expectations you'd have from the real world. Sure we are no pilots without real world experience. But this is a simulator based on real world data and not star wars squadrons with fictive aircraft with much room to argue about what to expect from a specific aircraft.


Edited by darkman222
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I am no programmer. But I think the real struggle is to add something without breaking another thing. Thats what this early access thing is all about. On the one hand , cool for us customers that we can be a part of the process and maybe point issues out to ED before the final release. On the other hand the end user is suddenly involved in a process only a few years ago no customer ever had any insight before. To communicate this by ED to the customers is a struggle itself.

It makes kind of sense that the "lock" tone comes just when almost all of the radar modes are finally modelled. I imagine it as a railroad track that was already there but the switch to it was only missing. And that goes for all the development involved in every DLC.


Edited by darkman222
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I checked the comprison video and used a stop watch to measure some numbers. The energy retension is almost 3 times as good. It takes 7 seconds to bleed from 490 to 470 for the old viper, and takes 18.9 seconds to bleed from 488 to 470 in the new viper, and the turning G is higher by 0.1. The energy bleed rate in this case is noticeably better. 

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On 3/15/2022 at 6:16 AM, karasawa said:

It is under-performing. There is still 4%-5% error and that sometimes means whether the F-16 comes out victory or victim.

This is a relatively small error, TBH. Ultimately, remember that our F-16 isn't running on real physics nor a simple lookup table, but a flight model. This means a set of mathematical functions which are defined by equations. It can't be just any equations, either, they must be possible to solve in real time. This imposes constraints on the model accuracy to actual aircraft tests, it cannot account for every kink in the airframe nor every small vortex the airframe induces. Thus, the curves will diverge somewhere. 

Also, IRL, this data can vary based on very minute things, anyway, you'd be hard pressed to get 5% error bars in a real world testing environment. Most of the time, with a real machine, they'll be larger. If 5% of performance is a difference between victory and defeat for you, your gameplan is wrong and you're essentially playing a lottery, hoping that the engine doesn't decide to run a little slow that day.

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2 hours ago, Dragon1-1 said:

Also, IRL, this data can vary based on very minute things, anyway, you'd be hard pressed to get 5% error bars in a real world testing environment. Most of the time, with a real machine, they'll be larger. If 5% of performance is a difference between victory and defeat for you, your gameplan is wrong and you're essentially playing a lottery, hoping that the engine doesn't decide to run a little slow that day.

I agree, the "by the numbers" rates are close enough for me. The level of error isn't really comparable when compared to errors we might infer from this next update:

2 hours ago, karasawa said:

The energy retension is almost 3 times as good. It takes 7 seconds to bleed from 490 to 470 for the old viper, and takes 18.9 seconds to bleed from 488 to 470 in the new viper, and the turning G is higher by 0.1. The energy bleed rate in this case is noticeably better. 

Holding on to more speed when turning is going to be much more discernable than a few % changes in STR.

We should probably as a community reconsider how to judge ED's Professional Flight Model.

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I just wanted to address HOW to judge the new FM because the predominant way is to find a chart of sustained turn rates for the Viper and then compare them to the game. imo that isn't really reflecting the major changes being made (or the ones that have already been made).

Also, the way you fly the Viper in a dogfight is going to benefit from these less table-friendly data-oriented changes we are noticing. So the players dogfighting in the Viper don't want the hard numbers chart people to drown out constructive criticisms just because the STR isn't a 1:1 match to data 100% of the time.

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4 minutes ago, Theodore42 said:

I just wanted to address HOW to judge the new FM because the predominant way is to find a chart of sustained turn rates for the Viper and then compare them to the game. imo that isn't really reflecting the major changes being made (or the ones that have already been made).

Also, the way you fly the Viper in a dogfight is going to benefit from these less table-friendly data-oriented changes we are noticing. So the players dogfighting in the Viper don't want the hard numbers chart people to drown out constructive criticisms just because the STR isn't a 1:1 match to data 100% of the time.

I already thought about it. Will post later.

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53 minutes ago, Theodore42 said:

I just wanted to address HOW to judge the new FM because the predominant way is to find a chart of sustained turn rates for the Viper and then compare them to the game. imo that isn't really reflecting the major changes being made (or the ones that have already been made).

Also, the way you fly the Viper in a dogfight is going to benefit from these less table-friendly data-oriented changes we are noticing. So the players dogfighting in the Viper don't want the hard numbers chart people to drown out constructive criticisms just because the STR isn't a 1:1 match to data 100% of the time.

I'vs got a perfect answer for you.

The best metric should be measuring the specific energy loss rate in a turn, since actual dogfight involves such turns.

Here is an explanation:

PS = specific excess power which means how fast the jet gains/loses energy in maneuvers.

 

Q: Why is it insufficient to measure STR (sustained turn rate) alone to verify the energy maneuverability?

A: There is an illusion that STR alone stands for energy maneuverability. If the game adopts a wrong drag profile, and tries to compensate the higher induced drag with modified zero lift drag or engine thrust, we may see an accurate peak STR, but the energy bleed rate at higher turn rate will still be higher than the flight manual. That is determined by equations of flight dynamics.

That's sometimes misleading. Some people claim the peak STR has small error, while some other people cry for high energy loss and they struggle to recover energy. They are not contradictory. We need to check the PS loss.

 

Q: How to get the ps since Tacview does not show that?

A: PS = (thrust-drag)*speed/gravity = longitudinal acceleration * speed / g = longitudinal G * speed.

Just check the “longitudinal G” in Tacview, read it, and multiply it by the true air sped (TAS), you get the ps value.

 

Example: (these numbers are for sample only) make a level turn at true air speed of 300 knots (154.3m/s), the lateral G force is 7G, and the longitudinal G force is -1.5G, we have:

Ps = -1.5 * 154.3 = -231.45m/s = -795feet/s

Level turn rate = square root (7^2-1) * g / speed = 6.92 * 9.8 / 154.3 = 0.4395rad = 25.18deg/sec

Read the flight manual for “300knots, 25.18deg/sec” and check if the ps is -795feet/s

(We may double check if the Gs are in body frame, but that won’t affect much the result)

 

Q: Why using true air speed instead of mach number?

A: The speed of sound in flight manual and that in DCS are slightly different. Using mach number causes some error. The speed of sound in flight manual is about 333.5m/s. This can be proven by picking a point in the E-M chart and do the maths.

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