DCS F-16 fidelity / your opinions?

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Unread post08 Oct 2019, 12:48

Some of you might be aware that we've had recently the so called early release of the most anticipated module of the Digital Combat Simulator since the beggining of time.
I wonder what is your opinion on the fidelity between the said simulator and the real deal. 2 cool videos and one very interesting comment that get my attention..

1. Eagle Dynamics release trailer
https://youtu.be/Bp6O-l00VwE
2. Matsimus (Grim Reapers) review https://youtu.be/FIvBN6e6mTQ

Im especially curious your thoughts on that: :P

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Unread post08 Oct 2019, 14:05

The DCS F-16 is broken. Almost nothing works and the FCLS is non existent. They just patched in an F/A-18 FBW.
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Unread post08 Oct 2019, 14:18

By non existent you mean that there is no custom-built algorithm that emulates the flight model & control laws used in a real Viper or that the FLCS pannel in the cockpit is not funcktional/accessible yet?
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Unread post08 Oct 2019, 16:16

I seriously wouldn't take DCS as real life (doesn't match the actual jets sim) even real life pilots have agreed on that. That being said, yeah, it seems it needs work.

Also, to further prove their invalidity (regardless of ED having actual pilots help with their mods/and these guys will IN NO WAY violate their Security Clearance over a computer game) on a YT dogfight: I observed a F-14B Tomcat at 260KIAS, 8,193ft, 8.1G, which is WAY above its Lift Limit on its real life EM diagram (even if you did extend its Max Lift line out to approx 9G). And in this game, it's still accelerating.... completely comical.
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Unread post08 Oct 2019, 16:46

f-16adf wrote:I seriously wouldn't take DCS as real life (doesn't match the actual jets sim) even real life pilots have agreed on that. That being said, yeah, it seems it needs work.

Also, to further prove their invalidity (regardless of ED having actual pilots help with their mods/and these guys will IN NO WAY violate their Security Clearance over a computer game) on a YT dogfight: I observed a F-14B Tomcat at 260KIAS, 8,193ft, 8.1G, which is WAY above its Lift Limit on its real life EM diagram (even if you did extend its Max Lift line out to approx 9G). And in this game, it's still accelerating.... completely comical.

I have the F-14B and I have never hit anything close to 8G at 260KIAS and I have never accelerated at times when I have hit 8G, so I don;t know what you saw.
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Unread post08 Oct 2019, 17:01

It's on one of CW Lemoine's vids.

There is a difference between adhering to a real life flight manual and "extrapolating" out to something that is not even there. Not to mention, rather ignoring energy bleed rates (Ps) at times.


Even "Growling Sidewinder" has a vid with the Tomcat turning at (if I remember correctly) at 500KIAS, 9.4G, then it not only maintains level flight but keeps accelerating in the turn (gaining energy) to 500KIAS plus, and at 10.4G. I can't remember the altitude but at those speeds and G ratings, in real life, it should be decelerating something like -2100Ps in a level turn.
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Unread post08 Oct 2019, 17:23

The FM gets tweaks nearly every update to fix things like that. Again, I am always losing speed and fast when I go to high G. I can't speak to what the FM was when those videos were made, but when I flew this weekend it bled speed in a hurry.
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Unread post08 Oct 2019, 17:42

The DCS F-16 is "Early Access" and that means very incomplete - in terms of software you will also hear the words "Alpha" and "Beta" thrown about to refer to very incomplete software.

Years ago software was released near to complete as possible - still had bugs (all software does) but this company now works to an Early Access model - seems to be the only way you can fund such a niche product.

I have been very interested in this release and saw a lot of the videos and tbh although it was labelled "Early Access" the videos made it look pretty well fleshed out. However upon trying it it seems like an empty shell and I understand from others it is nowhere near other Early Access releases.

Basically my advice is don't bother with it for 2 to 3 years then check the state then - because there is no point doing anything now.

I think the way they marketed this will have caused them some harm - you have to remember that most of the people buying this have no idea about software development and to add to that - don't give a flying fig about it either so there are probably quite a few disappointed people.
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Unread post08 Oct 2019, 18:49

At that speed zone, at least in the "A" model, that is known as its "hole". I've heard of that term used before and even Naval Aviator "Paco" Chierici has attested to that (AI Q&A). "B" model might still suffer from its effects, but slightly. I don't know and would have to ask. But... highly doubt at such low speed he would be at 8G. Over 8G at that speed, is way above the lift limit line (on all charts). And for a jet that weighs well over 50,000lbs, I'd imagine stall characteristics to have significant altitude and G loss. I've done power on and power off stalls in a -172 (and I'm certainly not implying that it is a high perf military jet), but what happens if you keep it there at the horn or even a little beyond? You lose altitude and you will not be doing much of anything for the next few seconds. (Put the nose down and recover) Still an altitude loss with no G's on it. And those were straight and level.

I've been in real life F-16 sims back in the early/mid 1990's. No offense to sim guys (use to play Falcon 4), a VR sim is simply not- nor will it ever be- the same sim at a fighter squadron base ops. And the Navy/MC/AF pilots who helped or advised them on these flight modules, as I said earlier, will never give a 100% pure deliberation of what they flew. They still have to abide by their SC.
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Unread post09 Oct 2019, 02:15

So I just did a bit of test flying to check some of your concerns. In a clean F-14B weighing 51,000lb (low fuel) I did onserve seemingly too high of a sustained turn above 0.9M under 5,000ft. I was able to sustain (aerodynamiclly speaking) a 9G turn. I pulled back power a bit to slow down and tried another high G turn. I stopped having 8G available around .75M and was down to 6.9G at .5M. I max AoA pull (stall) resulted in near immediate cessation of turn and uncommanded rolling actions.

Looking at the Manual, I was too light and too clean as the lightest cleanest F-14 is 4 sparrows and 4 sidewinders at 55,620lb. That planes Ps at 6.5G and 0.85M is +120. Ps 0 drops below 6.5G between 0.95 and 1.0M. As thrust equals drag, that same amount of lift (and thus same amount of drag) would be 7.1G assuming I had the same configuration. I was even cleaner. Given wave drag impacts on the shoulder mounted weapons, this MIGHT raise the Ps=0 G to 8. Maybe. I was seeing 9-9.5. High speed induced drag isn't high enough.

On the back end, The manual gives 6.5G down to 0.5M. The lift issues mentioned before apply, meaning the same lift should give the lighter plane 7.1G at that speed. Overall lift being too high is not proven or ruled out in the current iteration.

In my reduced speed pull, I slowed from 0.8M to 0.7M in 6 seconds at 20 AoA. Between 20 and 25 AoA it took 11 more seconds to slow to 0.6M. Pulling from 25 to 35 AoA I slowed to 0.5M in 5 seconds. 35-40 AoA (AoA increasing with same back-pressure BTW) slowed me to 0.39M in 3 seconds. Slowing from 0.5 to 0.4 in 3 seconds is -3.44G. this is an average Ps of -1,700. The FM shows ~-1000 but the weight would impact the deceleration as well because at the same AoA and speed we have the same Lift and Drag. the weight corrected Ps we should see on the chart is -1,580. Given my high AoA and somewhat reduced observed vs calculated expected G I may well have been over AoA for ClMax meaning induced drag is skyrocketing. High AoA induced drag seems pretty good.
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Unread post09 Oct 2019, 14:25

Spurts,

If you look at that old Grumman Chart from the mid-1970's. It gives the F-14B (with the Pratt 401-P400 motors) a 8G sustainable line from basically 3000ft and under. (I am unable to post it, I am on my way to Mackinac Bridge area- and away from my PC.) So if you estimate for SL it could be around 8.5G max, and guessing around .8IMN for speed. Down low (SL), I'd imagine the GE powered F-14B doing the near same. However, sustaining 9-10G in that game is a bit of a stretch to say the least. If you reference Figure 9.2 Specific Excess Power Diagram XI-9-6 (i.e. for Maximum Afterburner Gross Weight 55,620lbs, 50% fuel, 6.5G, +8AAMs/gun). If you run the Ps=0 line to SL altitude it intersects at .62 Mach number. Trace that on to its chart and to the left of that it should bow slightly downwards then further up (similar as to the other Ps lines), guessing to Max STR of 18.1 or 18.2DPS. Tear off the 8 missiles and a liberal guess should now be for a MAX STR of approx 19.1-19.3 DPS for SL. To the right of that 6.5G line the curve should bow outwards a bit past 7.5G and finally arching downward to approx 8-8.5G. On YT, people have tested that mod to 20-21DPS STR, again a bit of a stretch.

My issue is the 8.1G/260KIAS/8000ft. If you want to be a little liberal here, reference the 5Kft chart. At 260KIAS its lift limit is nowhere near 8.1G, in reality it is ~5.1G and at about -950Ps (even subtracting missile load-out). I have seen a couple of Hornet HUD vids and even the Rafale HUD vid---they are not anywhere near a similar high G at such low speed. Again, a Tomcat doing 8.1G at 260KIAS is an embellishment of the truth.

Even though the Tomcat did have a 6.5G service limit, operationally it could be flown (on occasion/certainly not on a daily basis) higher. In the new book about the F-14. Larry Muczynski said that on the pull up (it wasn't a turn) to avoid the Su-22 debris, he in fact hit 10.2G, and at 500KIAS. That was a hard pull into the vertical. The DCS mod has the Tomcat hitting 9.4-104G in a turn. Once again, an exaggeration of the truth.

One must also remember this is a question of money, they knew the F-14B mod was going to be one of their best selling (I have read this a number of times in the comment sections). So naturally, they would make it as impressive as possible. Take note what CW Lemoine says in that video: "he (the Mirage 2000) just doesn't have that power that the Tomcat, especially in this game has."

Also, since no complete FM are out for the Hornet or Mirage 2000, how do we know their VR performances area a 100% match for the real life jets. We don't-- the Navy and French pilots who advised still are not going to divulge the true capabilities of their jets. They cannot give out classified material.
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Unread post09 Oct 2019, 15:06

f-16adf wrote:My issue is the 8.1G/260KIAS/8000ft. If you want to be a little liberal here, reference the 5Kft chart. At 260KIAS its lift limit is nowhere near 8.1G, in reality it is ~5.1G and at about -950Ps (even subtracting missile load-out). I have seen a couple of Hornet HUD vids and even the Rafale HUD vid---they are not anywhere near a similar high G at such low speed. Again, a Tomcat doing 8.1G at 260KIAS is an embellishment of the truth.

That is why I tested what I did. As I said, they have been many patches to the Tomcat FM in DCS because, so they claim, they want it to be accurate, not awesome. When I tested on the latest software I DID verify that there is a problem above .9M of sustaining Gs that are WAY to high, but I was unable to turn 8G at 260 KIAS. I was down to 6.9G at 310 KIAS.

With something that is constantly being corrected it is disingenuous to look at a single snapshot, point to an error, and say "the developers don't care about accuracy". One of the issues they had mentioned was their FM testing environment had a lot of holes. They developed a new testing environment to allow them to look at specific cases in order to try and fill in the holes. As of RIGHT NOW, the hole is in sonic turning drag it seems.

Maybe I will load up some missiles and correct my weight to re-run the test, but I suspect there is still a problem with not enough induced drag above 0.9M.
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Unread post10 Oct 2019, 03:20

Spurts,

https://www.youtube.com/watch?v=gqUdcYvbzf8
I looked it up again. (I have only watched the first 14min of it)
At 11:33 mark the F-14B is at 637KIAS, 10275ft, and G keeps increasing to a whopping 15.6; at 11:44 jet is now at 496KIAS, 18,473ft and 13.6G; at 11:46 now at 436KIAS, 18993ft, and 14.9G.

And watch starting from basically 12:21 to 12:32 mark.
-at 12:22 jet is at 279KIAS, 9243ft, 6.6G
12:22 jet down to 247KIAS, 9292ft, 7.8G
12:26 jet up to 260KIAS, 8193ft, 8.1G
12:28 jet is at 292KIAS, 7101ft, 8.9G
12:31 jet is at 291KIAS, 6805ft, 8.2G
12:32 jet is at 286KIAS, 6960ft, 9.3G

At 13:43 F-14B starts a descending turn at 313KIAS, 3,263ft, and 9.9G (turning average G between 8-10), and by 13:54 the jet is at 319KIAS, 1565ft, and 12.1G.




How are all of these numbers possible? Wouldn't the F-14B possibly break apart with the former and stall with the latter?



This is the chart I was referencing earlier (mid 1970's F-14B with Pratt 401"s); Don't know if you have it or not:

F-14A early F-14B Mig-21 comparison.png
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Unread post10 Oct 2019, 05:27

I did not have that chart, only the FMs. Thank you for sharing.

Thank you for sharing the video. That was very enlightening.

Notes:
1 - We still don't know what SW rev they were using. As I said, FM tweaks abound.
2 - We don't know what game made they used. DCS has Game and Sim Flight Models.
3 - We don't know what Temp they set things too. I have seen videos of people "flight testing" in DCS and setting the temp to -15C in order to get amazing performance (increased air density)
4 - The F-14B had Landing Flaps out, not Flaps Auto, so all Flight Manual lift limits go out the window. I accidentally did that once in the Sim and broke the flaps, they would not retract.
5 - We don't know the weight.
6 - All high G excursions were brief and erratic. The pilot also had a LOT of uncommanded roll issues. Nothing here was steady state or sustained.

The F-14 development team has their hands full with the structural damage model, because there are reports of F-14s making it to 12G with no damage, and because Grumman tested it to be rated for 9.5G, so the 6.5G limit given to it by the Navy is artificial. So it's not cut and dry about when the wings rip off. You know what does happen though? If you go past 12 G the INS shatters and you lose your navigation equipment. They have internal systems failures modeled that you are unaware of and won't see watching that video. I will say they had G effects turned down or off because I have blacked out in the Sim for much less than that.

Your observations about KIAS and G are correct, and in this video are obviously true, but don't be an "armchair expert" when I have pointed out 5 items in the video that add too many unknown variables. By you own admission you don't play this simulator and your only experience is Falcon 4.0 and a real F-16 Sim. 1997 Falcon 4.0 was not that great. BMS 4.33 was much better at how the F-16 should behave. The F-14 is not the F-16. It has no built in limits other than physics.

Is DCS perfect? No.
Is the F-14 module developed by the DCS developers? No
Is the F-16 module developed by the DCS developers? Yes
Are all the modules of equal fidelity? Not even close.
Is the Model for the F-14 of higher fidelity than the model for the F-16? By light years.
Is the Model for the F-14 "finished"? No
Is the Model for the F-14 the most realistic representation outside the actual aircraft? Given the computers of the 70s and 80s... possibly.
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Unread post11 Oct 2019, 18:31

Good assessment - however your Christmas Card from Eagle Dynamics may be delayed in the post :D
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