My two cents on F-16 Turn Rate and the EM Diagrams - ED Forums
 


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Old 08-01-2020, 07:58 AM   #1
TheBigTatanka
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Default My two cents on F-16 Turn Rate and the EM Diagrams

Just an FYI to those currently testing the sustained and instant turn-rate of the viper, the drag index values in the HAF performance supplement for best performance are using a drag-index of 0 and a 22k pound jet (about 20% fuel). If you aren't testing like that, you won't get similar performance at all. Even just having missiles on the tip rails gives you a drag-index of 7, and it goes up really really quickly when you start hanging any pylons on there. The DCS viper does indeed seem to come pretty close to published data when using the right numbers to test turn performance.

Reading EM diagrams isn't very intuitive either, it's not as straight forward as it seems. For those who think you should be able to "fight at 9Gs" -- that is a very fleeting moment. If you look at the published 9G line on the dog-house, you'll see that the Ps values are significantly negative and very far from the Ps=0 lines.

That being said, I'm not a viper pilot, but I am a USAF pilot and I have a relatively decent grasp of this stuff. Are there problems with the DCS viper flight model? Yes, particularly when it comes to thrust (under-powered), and this is observed by high time viper instructors who, obviously, really know their vipers -- so let's hope that the viper flight model in DCS is still WIP and they are continuing to take input from their SMEs.

There's also been a lot of talk about the viper vs hornet flight models. Should the Hornet be able to out-perform the Viper in a rate fight? Obviously not -- but the Hornet also gets a vote, and doesn't have to fight that fight. It does seem like the hornet is over-powered, or more likely the viper is under-powered currently, but maybe that will change. I'd be curious to see how people are dying to hornets in DCS -- I bet a lot of times it isn't because they are out-performed, but because they are falling victim to a BFM game plan.

I don't want this thread to fall apart into something that gets closed by admins, but I thought it was important to talk about people's expectations in the viper vs what the charts say we can do (and the importance of knowing how to read those charts).

Lastly, can someone turn up the position lights on the tanker?

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Old 08-01-2020, 01:44 PM   #2
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I agree that the Hornet is overpowered in rate fights. Also Viper pilots in DCS cannot max perform the jet because of the unrealistic G-effects in DCS right now.
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Old 08-01-2020, 06:48 PM   #3
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"unrealistic g effects" is a bit relative. If I pulled 5 GS smoothly right now IRL, I'd probably pass out. To get a true sense of the flight model, fly with G effects turned off in sim. I'm sure it's something being looked at globally.

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Old 08-01-2020, 07:23 PM   #4
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Quote:
Originally Posted by TheBigTatanka View Post
Just an FYI to those currently testing the sustained and instant turn-rate of the viper, the drag index values in the HAF performance supplement for best performance are using a drag-index of 0 and a 22k pound jet (about 20% fuel). If you aren't testing like that, you won't get similar performance at all. Even just having missiles on the tip rails gives you a drag-index of 7, and it goes up really really quickly when you start hanging any pylons on there. The DCS viper does indeed seem to come pretty close to published data when using the right numbers to test turn performance.
You do realize there are performance graphs for 50% fuel and DI = 50 (i.e. 4x AIM120's + 2x AIM-9's + 2x fuel tank pylons + 1 centerline pylon) right ?

Hence most testing is done following the normal A2A load out above at 26,000 lbs.
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Old 08-01-2020, 07:38 PM   #5
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Hummingbird,

I do calculate drag index values and use the chart for what I'm doing; but I suspect most testers do not. The data that DCS has put out is using that best case scenario, lightest, cleanest jet... and I think people expect to see that kind of performance all the time.

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Old 08-01-2020, 07:59 PM   #6
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The more I've tested the the Gex warmup, the more my mind is changed that the g tolerences are ok. The F-16 does need to change a bit in the sense that It needs to allow for a more sustained 9g pull without blacking out within 3 seconds. However as pointed out above your 9g threshold is small and with an actual combat load or observed Bingo fuel state, is not likely to actually appear.

To the point of the OP, just a quick rough guesstimate revrals, 22% fuel is like ~1600 lbs of gas. So not really the fuel state you want to be in when starting a bout of BFM/ACM when you're still miles from home or a tanker. In reality you would.have Bingo'd out well before that. So.i.think you're right, a level headed approach as to managing expectations vs reality is always healthy.
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Old 08-02-2020, 12:40 AM   #7
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Quote:
Originally Posted by TheBigTatanka View Post
There's also been a lot of talk about the viper vs hornet flight models. Should the Hornet be able to out-perform the Viper in a rate fight? Obviously not -- but the Hornet also gets a vote, and doesn't have to fight that fight. It does seem like the hornet is over-powered, or more likely the viper is under-powered currently, but maybe that will change. I'd be curious to see how people are dying to hornets in DCS -- I bet a lot of times it isn't because they are out-performed, but because they are falling victim to a BFM game plan.
We had a training with 4 groups (each 1 hornet, 1 viper) this week for about an hour of good dogfighting.
hornets had pylons on, vipers were clean. both planes had full internal fuel. fight ended at 2000lbs for vipers (at which point the hornets were at about 4500 lbs or so) the skill level was completely mixed, and even when the hornets went for HUD BFM and 2 circles, there was not a single time that the viper had anything on it.

From the feeling would have also said that the engine is too weak at the moment (though I must say that I have most experience with block52 models). But hey, I'll try to collect the diagrams and see .. if you have anything you can share, I'd be happy about something to test against.
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Old 08-02-2020, 09:27 AM   #8
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Hey deadpool, I agree the F16 currently feels a bit under powered. I do think that most people, myself included, can tend to over look our BFM errors and chalk things up to some known inaccuracy in the simulation. I bet we could go through the TV of your sortie and see where and how you could have changed your fight in order to drive toward a victory.

I'd say some of the most common BFM errors are

1. Incorrect Airspeed at TCE.
2. Failure to identify winning or losing cues.
3. Failure to identify attack cues.
4. Failure to properly repo.
5. Incorrect execution of turn reversal.

I'd say these are my top 5. These are just a few. But they are ones I observe a lot. These have nothing to do with a specific jet, they affect all jets equally. Do any of these, more than another guy and you're going to see some poor results.

F-16 specific, My top 3 would be:

1. Failure to maintain TCE Airspeed.
2. Failure to achieve/exceed limiter pull.
3. Opening the turn circle due to high thrust.
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Old 08-02-2020, 03:26 PM   #9
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Hey 000rick000,

I am absolutely willing to admit that I am not a BFM expert. I was only one F-16 that day, and we had some with experience with a lot of BFM in that other sim.
I have a cockpit video recording of my fights and a tacview and am up to learn something.
I'll send you a PM about maybe having a look at them together.

The matter of fact is that the hornet pilots were at the same skill level, some never having shown any BFM interest in before. And yet the overall picture was not as deciding as I had thought.
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Old 08-02-2020, 06:19 PM   #10
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I think the hornet lends itself to success in BFM for people who don't have much BFM training. The ability to point the nose at low speed is huge; and it is easy to do. In a viper, you are more maneuverable, but you have to fly the jet by the numbers to the control zone, and not pull the bandit to the HUD until you have attack cues, including a speed advantage (rule of 3s).

I've been doing a lot of viper v viper fighting in DCS lately, I'd love to set up perch and butterfly sets against a hornet pilot to see what can be learned.



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