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If you want 2 circle in a F-16, stay above 10000 feet.


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12 minutes ago, Mirage2425 said:

I'm definitely not doing that.  I'm only pulling to the green donut. The stick isn't full back.  Trying to just maintain 13 degrees of AOA.

 

Are you trying to do this with a constant stick position or something? I'm not sure how you wouldn't be able to hold a specific AOA.  Are you climbing?

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I'm trying to keep the FPM on the horizon.  I was holding the same stick position.  If I let off the stick wouldn't that increase rate?  I need to try it again.  It's been a while and I've been focusing on A2G.  That is my recollection though.


Edited by Mirage2425
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18 hours ago, Dragon1-1 said:

I'm using the HFFM charts, since they're the most complete, if you want an apples to apples comparison of different blocks, pretty much the only option.

@Dragon1-1 Where can i find those pls?

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On 4/12/2021 at 5:45 AM, Dragon1-1 said:

I'm actually speaking from the other sim experience (and my physics education) and some EM charts, I don't have enough DCS stick time to know how it is in here. 🙂 They have SMEs there, too. I do know that Block 30 in question was a real hot-rod, being much lighter (thus less AoA for the same lift to weight ratio) and less draggy than the Block 50. I would actually prefer to have that in DCS, as opposed to the Block 50. 

 

Either way, the charts I have are for DI=38 and GW of 28670lbs, and the PS=0 curve doesn't quite reach the 9G line. That's at full burner at 5000ft. Obviously, if you're in full burner the GW won't stay at that level for very long, and if your DI isn't 38 (say, you're not hauling a centerline jamming pod), the situation probably looks different. Unfortunately, I don't have charts for any other configuration. 

 

Of course, the real DCSism is that you can't actually hold 9G for any length of time without blacking out. It completely fails to model the Viper's unique seat position, which helps reduce the impact of Gs acting on the pilot by a fair margin. 

 

Block 30 is less draggy? Aren't Block 30 and 50 the same aerodynamically? 

 

And I don't think Block 30 is "much lighter". Like Mover said, it's just 1000 lbs lighter. Block 50 also has about 1400 lbs more thrust than Block 30. Or should I say "much more" thrust?

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3 hours ago, oldtimesake said:

From General Dynamics:

 

block50 is about 1200lbs heavier than block30 in Basic Flight Configuration

 

weight-growth-2.jpg

 

Thx for the info. From my calculation, Block 50's TW ratio with increased 1400 lbs of thrust and 1200 lbs of weight is actually slighter better than Block 30's? Why do ppl claim Block 30 has better TW ration than Block 50?

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8 hours ago, SCPanda said:

Thx for the info. From my calculation, Block 50's TW ratio with increased 1400 lbs of thrust and 1200 lbs of weight is actually slighter better than Block 30's? Why do ppl claim Block 30 has better TW ration than Block 50?

 

Installed thrust and static thrust are not the same thing. 

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It is not that easy, because thrust curves differ from engine to engine. There is no fixed number, and T/W ratio is from a specific point (the maximum thrust output). The amount of thrust can differ between various engines on the same altitude and speed, the 129 has a slightly higher bypass ratio than the F100-229 and it is a different engine as the 100 used in the blk30.
It is not a single number, and also a higher weight will give slightly different induced drag that has more effect on lower speeds (AOA) and other effects (for example to the 50 lowering the nose on 100kts on landing and the 30 at 80 knots).

Aerodynamics aren't simple, and you can't say "this is better", "the 30 turns better than the 50". A 50 will outperform the 30 on higher mach numbers or altitudes, while the 30 might have an edge in a turning fight. Because the GE 129 is way better at altitude and speed, while the blk30 is lighter. But: The 30 has no IFF interogator or HMCS, both of those have more impact on the fight as the increased weight. So they decided to bring more stuff into the plane and increase thrust.
If you ask about which plane turns better or is faster, then you have to state the exact conditions and the answer will only be true for a certain "point in space" for a certain loadout, a certain speed, pressure altitude, AOA (G), even temperature.

There isn't that much of a difference, because the 50 partly compensates the weight with thrust, and the lighter weight of the 30 doesn't mean that much with less thrust.
 

But...

- We have a specific variant, the 50 with GE 129

- So we trust in ED to match real life data, which will most likely result in a similar end speed, better lift at higher AOA's (so less induced drag) and a slightly slower acceleration in level flight because probably induced drag is too high and parasite drag too low

So I'd say we wait for 2.7 and see if that brings any FM fixes. I hope so, and if it does, it will greatly affect my decision on the apache but that is another thing.

 

Keep in mind that except from clean practice conditions, no dogfight ever is balanced. Usually, the one who decides to enter it dictates his wishes to that fight to give him an edge which ideally should outweight any disadvantages.
I have rarely lost a dogfight I willingly entered, but have rarely won a fight I didn't chose. I messed up a fight on buddyspike recently when my AIM-120's failed and ended up in a gunfight with a hornet which I almost failed. Almost. And I sacrificed so much, misjudged to situation, went for kill just to get me almost killed out of a plain advantage. I had to rely on guns, and that bothers me, because I wanted to have that kill, went careless and almost paid for it.
Don't rely too much on charts, and minor differences between similar airframes. It is carelessness, pure SA and pure energy management and situation judgement that gets you killed. There is no general road to success, no one-thing-to-rule-them-all. This is especially true for 1 vs 2 or 2 vs 1 or 2 vs 1 or similar situations. The better team wins.


Edited by TobiasA
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Guess what, ED used to do things right. DCS F-16 on release was a potent dogfighter (for a while) which turns surprisingly well. The sustained G curve was slightly lower than flight manual below Mach 0.5 but the error was less than 4%. Grim Reaper used to make videos like this and it had pretty good win rate against F14/15/18/Su. 

These were the good old days and all of a sudden a patch halved viper's life curve slope.

 

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Possible. It is still possible to revert to an older DCS version and test it. But as far as I can remember back when when the F16 came out the even more restriktive G modelling and the missing radar gun sight was standing in the way for proper dogfights. So maybe just no one really was doing guns dogfights back in 2019 and thats why nobody realized that a possible error was induced.

They also did  a video about confirming the turn rate few weeks later after that video you posted.

 


Edited by darkman222
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Posted (edited)
43 minutes ago, darkman222 said:

Possible. It is still possible to revert to an older DCS version and test it. But as far as I can remember back when when the F16 came out the even more restriktive G modelling and the missing radar gun sight was standing in the way for proper dogfights. So maybe just no one really was doing guns dogfights back in 2019 and thats why nobody realized that a possible error was induced.

They also did  a video about confirming the turn rate few weeks later after that video you posted.

 

They just confirmed the peak turn rate. In fact the turn rate below Mach 0.5 is always below flight manual.


Edited by oldtimesake
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2 hours ago, darkman222 said:

Possible. It is still possible to revert to an older DCS version and test it. But as far as I can remember back when when the F16 came out the even more restriktive G modelling and the missing radar gun sight was standing in the way for proper dogfights. So maybe just no one really was doing guns dogfights back in 2019 and thats why nobody realized that a possible error was induced.

They also did  a video about confirming the turn rate few weeks later after that video you posted.

 

 

 

The best part of this is that we now have an EM diagram for a clean F-16 with the F110-GE-129 engine that we know the Blk 50 uses, with a drag index of 0 and GW of 22,000 lbs at sea level. I'm going to conduct my own tests in standard conditions and at that weight.

 

 

EDIT: Update

 

Yeah, it actually checks out. I took the pylons off the F-16 ("Remove Pylon", not just "Remove Payload") and set the weather to 15° C.  I don't know how to set other parameters like pressure and humidity, but this is good enough I think. I had to set G forces to NONE for this test to get GLOC out of the picture. I removed all ammo and set fuel to 33% so I had a few lbs to use to get up to speed before hitting 22,000 lbs.

 

image.png

 

 

I then pushed the throttle to max afterburner and attempted to fly best sustained turn rate at Ps =0. I'm a sloppy pilot, but I flew a few circles trying my best to keep speed at around 433 knots and between 300 to 500 ft altitude. I'm sure there are better virtual pilots out there who could hold more steady than I did, but I waited until my TacView was pretty stable and took this screenshot right there. I had burned enough fuel that I was down to ~21,500 lbs by the time this screenshot was taken. If you look at the GW Effect table on the EM diagram, every 500 lbs is another .5 deg/sec, so I'm fairly close to what the chart says.

 


image.png

 

 

The turn rate drops a bit if you load tip AIM-120s and a pair of CATM-9, along with a centerline drop tank that I dropped before performing the test (leaving the pylon there to add drag). 20.6 to 21.2 sustained is about where I averaged, and was closer to 21,200 lbs at the time of this screenshot. Note that because of the weight of the missiles, I adjusted my internal fuel to 18% so that I would wind up at around 22,600 lbs GW after dropping the centerline tank, giving me enough fuel to get the turn set up before taking this screenshot.

 

image.png

 

 

Well, here's a screenshot of the EM diagram from the Grim Reaper video. Hope this info helps somebody!

 

image.png


Edited by Xavven
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2 hours ago, Xavven said:

 

The best part of this is that we now have an EM diagram for a clean F-16 with the F110-GE-129 engine that we know the Blk 50 uses, with a drag index of 0 and GW of 22,000 lbs at sea level. I'm going to conduct my own tests in standard conditions and at that weight.

Please test Ps < 0.

 

DCSF16vsRealLife.thumb.png.b853d05d2442b01b372a23d13a1e65f1.png


Edited by Ватрушка

5900X / G.Skill 32GB @3600MHz cl16 / PowerColor Red Devil RX 6800 XT / SSD / LG 27GL850 144Hz / Thrustmaster Hotas Warthog

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17 minutes ago, Ватрушка said:

Please test Ps < 0.

 

 

 

 

Sure! What point in particular do you want? Here's my test for corner speed.

 

I started at about 2100' and ~360 KIAS and dropped about 400-500 feet per second in altitude to check quickest turn in a clean F-16 (pylons removed) at nearly 22,000 lbs on a 15° C day. Result was in 25.5 deg./sec at its peak, but look at this... as the turn continues and I lose altitude, even though I maintain G and speed, my turn rate goes down substantially over two seconds later in the turn, down to 23.3 deg./sec.. What's with that? Am I flying it wrong? According to the chart, dropping 0.5 G would lose about 1 deg./sec. of turn rate. But I only drop 0.1 G at nearly the same speed and I lost more than 2 deg./sec.

 

image.png

image.png

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Posted (edited)

You should also show the corresponding AOA, otherwise the lift curve slope error could not be visualized (which increases the speed bleed).

 

You can lock fuel to a specific weight so there's no need to make compensation.

 

By ps < 0, we mean that you should test if the viper really bleeds speed at the corresponding ps number, which requires timing. It seems that you are just measuring the peak ITR. We need this because the lower lift curve slope will result in higher speed bleed, which can not be visualized by your test above.

 

Here are my suggestions:

 

load 6 amraams (DI=50) and 55%-60% fuel to make the total weight = 26000 lbs, lock it. and disable blackout.

 

Try measure its sustained turn rate at Mach = 0.4, Mach = 0.5, Mach = 0.7, Mach = 0.8.

 

Show its corresponding AOA.

 

I am sure you will find the turn rate below Mach = 0.5 is lower than flight manual, and the viper needs huge amount of AOA compared to the 15 deg/9G on flight manual.

 

 


Edited by oldtimesake
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Posted (edited)

Here is what I got:

 

6 AMRAAM, WT = 26000 lbs, Mach = 0.4, DCS F-16 sustains 15deg/sec, while a real F-16 sustains 16deg/sec.

 

A clean DCS F-16 needs 23.3deg AOA to reach 8.5G at Mach 0.75, while a real F-16 (loaded with 6 ARMAAMS, wt = 26000lbs) requires 15 deg AOA to reach 9G at Mach 0.67.

 

Confirmed from other players:

 

Capture.PNG

 

 


Edited by oldtimesake
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2 minutes ago, oldtimesake said:

You should also show the corresponding AOA, otherwise the lift curve slope error could not be visualized.

 

You can lock fuel to a specific weight so there's no need to make compensation.

 

By ps < 0, we mean that you should test if the viper really bleeds speed at the corresponding ps number, which requires timing. It seems that you are just measuring the peak ITR. We need this because the lower lift curve slope will result in higher speed bleed, which can not be visualized by your test above.

 

 

 

 

 

Ah, thank you. My AoA was 17.3 in the first screenshot and 18.1 in the second screenshot (I went back to tacview and tried to get close to the same frames and added the AoA label).

 

So wow, yeah, getting the exact Ps number is going to be hard! The best I can do is give you the timestamps for the first screenshot and the second, then do the math against the altitude readings, but the error here could be huge because tacview is not giving me milliseconds.

 

Screenshot 1: T=1:28, Altitude=1961

Screenshot 2: T=1:30, Altitude=1058

 

Altitude loss = 903 feet / 2 seconds = 452 FPS

 

So the other thing I can do is measure across the whole turn to get a bigger average.

Start of turn: T= 1:27, Altitude = 2077, IAS = 372, AoA = 16.8, G = 7.5

End of turn: T = 1:31, Altitude = 800, IAS = 361, AoA = 18.8, G = 7.5

 

2077 - 800 = 1277 / 4 = 319 FPS and a loss of 11 knots (sorry, I really didn't fly it perfectly)

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Please notice: the weight conversion table on the flight manual is simplified and linearized. For more accurate calculation, one should apply the law that the normal load factor is inverse proportional to the weight.

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2 minutes ago, oldtimesake said:

Here is what I got:

 

6 AMRAAM, WT = 26000 lbs, Mach = 0.4, DCS F-16 sustains 15deg/sec, while a real F-16 sustains 16deg/sec.

 

A clean DCS F-16 needs 23.3deg AOA to reach 8.5G at Mach 0.75, while a real F-16 (loaded with 6 ARMAAMS, wt = 26000lbs) requires 15 deg AOA to reach 9G at Mach 0.67.

 

 

 

 

Yeah, so far I've been just measuring against the EM chart that Wags gave the Grim Reapers.

 

If we start talking about the real F-16, then if the numbers you provided are true, DCS has very poorly represented the AoA needed for a given G. How disappointing!

 

Plus, if Mover says an F-16 at 400-450 KCAS below 5000' accelerates even when pulling 9G and it has 2 AIM-120 and CATM-9 on it, I believe it. In DCS, it's clear from my testing that I can make the completely clean jet with 30% fuel remaining bleed speed by just pulling 8.5 G in a level turn on standard day conditions. I have to be going over 450 knots before the DCS F-16 starts accelerating under full stick deflection -- at that point I have to either back off the throttle or gain altitude to stop the runaway acceleration.

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15 minutes ago, Xavven said:

 

Ah, thank you. My AoA was 17.3 in the first screenshot and 18.1 in the second screenshot (I went back to tacview and tried to get close to the same frames and added the AoA label).

 

So wow, yeah, getting the exact Ps number is going to be hard! The best I can do is give you the timestamps for the first screenshot and the second, then do the math against the altitude readings, but the error here could be huge because tacview is not giving me milliseconds.

 

Screenshot 1: T=1:28, Altitude=1961

Screenshot 2: T=1:30, Altitude=1058

 

Altitude loss = 903 feet / 2 seconds = 452 FPS

 

So the other thing I can do is measure across the whole turn to get a bigger average.

Start of turn: T= 1:27, Altitude = 2077, IAS = 372, AoA = 16.8, G = 7.5

End of turn: T = 1:31, Altitude = 800, IAS = 361, AoA = 18.8, G = 7.5

 

2077 - 800 = 1277 / 4 = 319 FPS and a loss of 11 knots (sorry, I really didn't fly it perfectly)

Using your numbers:

 

Start of turn: T= 1:27, Altitude = 2077, IAS = 372, AoA = 16.8, G = 7.5

End of turn: T = 1:31, Altitude = 800, IAS = 361, AoA = 18.8, G = 7.5

 

2077 - 800 = 1277 / 4 = 319 FPS

 

You are holding around 21.8-22deg/sec at about Mach 0.56 and according to the flight manual your ps loss should be around 100-200 feet/sec. The DCS F-16 is suffers twice as much.

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3 minutes ago, oldtimesake said:

Using your numbers:

 

Start of turn: T= 1:27, Altitude = 2077, IAS = 372, AoA = 16.8, G = 7.5

End of turn: T = 1:31, Altitude = 800, IAS = 361, AoA = 18.8, G = 7.5

 

2077 - 800 = 1277 / 4 = 319 FPS

 

You are holding around 21.8-22deg/sec at about Mach 0.56 and according to the flight manual your ps loss should be around 100-200 feet/sec. The DCS F-16 is suffers twice as much.

 

I wonder if Tacview is giving incorrect turn rate information, then? It thinks I held between 21.5 and 25.5 deg./sec. through the 4 second turn with it being in the 24 deg.sec. range for the vast majority of that time. My G peaked at 7.9 and was 7.7 for the majority of it. There are some formulas to calculate turn rate for a given speed and G though -- is that what you're using?

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Posted (edited)
21 minutes ago, Xavven said:

 

I wonder if Tacview is giving incorrect turn rate information, then? It thinks I held between 21.5 and 25.5 deg./sec. through the 4 second turn with it being in the 24 deg.sec. range for the vast majority of that time. My G peaked at 7.9 and was 7.7 for the majority of it. There are some formulas to calculate turn rate for a given speed and G though -- is that what you're using?

The turn rate can be calculated from speed and G load. If the turn rate reading is incorrect you can calculate it your self. I know the tacview turn rate has some issue but I never use them directly.

 

turn rate = centripetal acceleration (in SI) / speed (in SI)

 


Edited by oldtimesake
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image.png

 

Doh! The forum ate my reply... let me retype it. If I take my speed of mach 0.56 and average G of 7.7, it puts me at the green dot above. I had calculated -319 FPS over the 4 second turn, so that appears to be in the right ballpark for what the chart predicts my energy loss was, not accounting for the 11 knots of speed loss (I don't know how to convert that into FPS, sorry!).

 

I did have about 0.5 deg./sec. faster turn rate than the chart predicts, but that could be because of my fuel state putting me below 22,000 lbs.

 

I also wasn't max performing the aircraft for all 4 seconds, but I did momentarily hit 7.9 G, 25.5 deg./sec. turn rate, and what I think is -450 FPS, but that last number could have some error because I'm not getting milliseconds measured in Tacview, so it could be off by as much as 50% if I tac on even a half a second on either side of the measurement.

 

I'm not trying to argue that the DCS F-16 is modeled correctly, just that from the very limited, isolated test I did, it doesn't seem way off from the chart. But I'm also flying without tip AIM-120s, and I believe the F-16 Drag Index = 0 is actually supposed to include them. This test was as optimistic as possible, overly so probably. And I don't dispute that our DCS F-16 is way off from the real life F-16. This EM chart is probably not correct anyway -- as Mover said that info is classified. I wonder where this comes from actually.


Edited by Xavven
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Posted (edited)
29 minutes ago, Xavven said:

image.png

 

Doh! The forum ate my reply... let me retype it. If I take my speed of mach 0.56 and average G of 7.7, it puts me at the green dot above. I had calculated -319 FPS over the 4 second turn, so that appears to be in the right ballpark for what the chart predicts my energy loss was, not accounting for the 11 knots of speed loss (I don't know how to convert that into FPS, sorry!).

 

I did have about 0.5 deg./sec. faster turn rate than the chart predicts, but that could be because of my fuel state putting me below 22,000 lbs.

 

I also wasn't max performing the aircraft for all 4 seconds, but I did momentarily hit 7.9 G, 25.5 deg./sec. turn rate, and what I think is -450 FPS, but that last number could have some error because I'm not getting milliseconds measured in Tacview, so it could be off by as much as 50% if I tac on even a half a second on either side of the measurement.

 

I'm not trying to argue that the DCS F-16 is modeled correctly, just that from the very limited, isolated test I did, it doesn't seem way off from the chart. But I'm also flying without tip AIM-120s, and I believe the F-16 Drag Index = 0 is actually supposed to include them. This test was as optimistic as possible, overly so probably. And I don't dispute that our DCS F-16 is way off from the real life F-16. This EM chart is probably not correct anyway -- as Mover said that info is classified. I wonder where this comes from actually.

 

 

That is incorrect. 372 knots is around mach 0.56 but not accurately mach 0.56. You are in a sensitive region where small change in turn rate results in much higher change in  ps. 

372knots is 191.4m/s, 7.5G normal load factor results in 7.43G centripedal acceleration, which is 72.84 m / s^2. Turn rate = 72.84/191.4 = 0.3805rad = 21.8deg/sec. From the manual chart at 21.8deg/sec the ps should not significantly exceed 100 ft/sec.

 

Bear in mind I didn't even counted the fact that true air speed is slightly higher than IAS which will down grade the turn rate (and the ps bleed rate) even more.


Edited by oldtimesake
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