Xavven

Huh? No, I went to the mach 0.4 line, then found the 4 G line and the 5 G line, counted there are 8 squares between them, and since I was pulling 4.6 G I put my green dot on the 4th/5th line up from where the 4 G line intersects the 0.4 mach line.

Sorry, that was a typo. Here's a screenshot from the mission editor. I was at 22,004 lbs.

Alright, here are my tests... I check the unlimited fuel box this time, set fuel to 29% and gun to 10%, putting me at 20,004 lbs 22,004 lbs (EDIT: Corrected typo) and I'm locked to it. This is from a clean (pylons removed) F-16 and weather set to 15° C. This time I'm on the DCS 2.7 patch level though, which was released today. I held a level turn at about 270 knots indicated on the HUD, but Tacview inflated that to 281 for some reason. Anyway, pulling 4.6 G and keeping altitude and speed level, I took this screenshot once stable. I Checking the chart and ignoring turn rate, just going off of G and speed alone, it puts me close to the Ps = 0 curve (green dot). It checks out. Okay, so what about if I pull 5G and descend to hold speed constant? You can see in the screenshot below that I start by holding a 4.6 G level turn at 266 knots, then pull 5G and the turn tightens. I adjusted my descent rate until I could get 5.0 G and 250-265 knots stable and flew it right into the water. In Tacview, it inflated my speed to 276 despite my lower speed on the HUD in DCS. Here's the screenshot as close as I could get it to 2 seconds before impacting the water. My altitude loss appears to be in the vicinity of -100 FPS. This turn was harder to make completely stable and I varied between 4.7 and 5.0 G initially on the way down but it was pretty stable right before I hit the water. Checking the chart again, I'm at the green dot again. I'm reasonably close to the Ps = -200 line and I'm not seeing more energy loss than that in DCS. I'm not trying to put my thumb on the scale to try to be right or anything. I'm genuinely interested in getting to the right answer. Criticism welcome. If I'm flying it wrong, setting up conditions wrong, etc. I'm happy to be corrected. From what I'm seeing it's not crazy off the chart when just looking at G, speed, and altitude loss (or maintenance). I can't speak to AoA requirements though, and whether this EM chart is true to the real life F-16 blk 50 is another discussion entirely.

Yeah, definitely a good trick for STR. Unfortunately, I would hit the ground trying to test instantaneous turn rate. -400 FPS = crash in a few seconds.

OK, so basically I need to repeat my test but try to get 24.9 deg./sec. of ITR without banking more than 90 degrees, correct? OK, I'll test that.

But in this case I'm banked more than 90 degrees. So I'm not trying to counteract gravity at all -- it should be actually helping my turn. Right? And the turn rate I care about is not just the change in magnetic heading, but the change in my nose position in all coordinates including the vertical.

So I slept on it, and I thought I'd use http://www.csgnetwork.com/aircraftturninfocalc.html to see if it agreed with your math, @oldtimesake. And it does. If I enter 372 knots as the speed and 82.55° as the bank angle to force it to give me 7.7 G, it tells me I should be turning 360° in 16.2 seconds. That's 22.2 deg./sec. It's this part that I'm not understanding: We're taking out 1 G here? Is that to account for the force of gravity? I noticed that the Aircraft Turn Information Calculator agrees with Tacview's turn rate information on a mild turn at low G, for example holding 4 G at 500 knots. Where it doesn't agree is on my max performance turn where my bank angle is greater than 90 degrees. The calculator and Tacview disagree on turn rate by almost 3 deg./sec, but that's because I have to put 82.62° as the bank angle to force 7.7 G at 368 knots. It thinks my turn rate is 22.8 deg./sec. but tacview thinks I'm at 25.5 deg./sec. at that point. But again, my actual bank angle wasn't 82°, it was over 90°. I'm not sure it's correct to take the sqrt of 7.72 - 1 here to get centripetal force.... is it?

Awesome Color me impressed. I'll have to turn that into a Excel sheet so I can do the conversion at will. And Tacview is like 1.5 deg/sec off on its turn rate calculation, then. Alright, using the same chart I was pointing to earlier, picking the point 22.5 deg./sec. and mach 0.56, Ps should be -200. I'm at -319 at best, and that's not counting my 11 knots of speed lost on top of that. So our DCS F-16 is bleeding way too much energy, and this was giving it every advantage possible... below the GW listed on the chart and no 2x AIM-120 that are included in a DI = 0 viper (see table below)

Ah, thank you for the correction. I figured there would be additional fuzz here from the speed of sound converting to IAS and some other stuff in there I really don't understand. So instead of me picking the point based on 7.7 G and 0.56 Mach, I should be converting 7.7 G and 372 IAS to a turn rate, finding that point on the chart, and looking at the Ps. Yes? Can you re-do that calculation for 7.7 G instead of 7.5 G? 7.5 G was my starting and ending load but only because those were point I arbitrarily picked as the start and end of the turn. For the vast majority of the 4 seconds I was between 7.7 and 7.9 G.

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.

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?

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.

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)

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.

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

LOL!!! The F-16 killing itself is somehow appropriate to this thread

So you've both made your positions clear, then. I think I've decided which source I believe is more credible and convincing.

Charts are pretty convincing on the one hand... On the other hand, maybe you should ask Mover how he knows. Not sure if I can hint any harder than this.

Just an observation -- those of us who are not IRL fighter pilots (most of us, in other words) tend to put a little too much faith in DCS' accuracy and realism. We observe how our favorite planes and/or missiles perform in DCS and assume that since Eagle Dynamics spent a lot of time on the flight model, the real thing must behave this exact way too. Then we build tactics and explanations that might work well in DCS and think that must be the optimal tactic in real life, too. I've made that mistake a few times, myself. We're lucky that pilots and SMEs frequent these forums to help correct these misunderstandings. When that happens, I'd recommend typing less and reading more. ;)

I can find two different sea-level F-16 EM diagrams on a google search (heading of GR1F-16CJ-1-1 and T.O. 1F-16C-1-1). Depending on which one you look at, corner speed is either 0.55 mach or 0.50 (so 330-360 IAS), and Ps = 0 peaks at either 0.78 mach or 0.66 (so 440-520 IAS) right at the 9G line. The slope of the Ps = 0 line is about 0.5 deg./sec. for every 0.1 mach increase in speed until the 9G limit is reached, at which point there's an abrupt negative slope. Sadly, I don't have access to a big array of EM diagrams in a manual that lets me choose the weight, altitude, engine, and drag index I want for any situation, but knowing the general range of these numbers for a few different altitudes is good enough IMO, as there are so many other variables factoring into what kind of turn at what speed you should be doing. I could have bad information, of course, but until someone can get me something better, this is where I'm at. And it might be illegal to share anything anyway. I will say, though, that if the fight starts 2-circle from a neutral pass, even 1 deg./sec. of extra turn rate is something I'll take by flying best STR instead or corner speed, even if it means I'm at the G-limit.

Ooo... this sounds nice. Where is this posted? Are we getting performance improvements for the F-16?

Oooorrrrr... or, and hear me out on this one, we could have the boom operator just say "return pre-contact"

Well, I could be wrong, but I think corner speed is max instantaneous turn rate (energy depleting), not sustained. https://www.cnatra.navy.mil/local/docs/pat-pubs/P-1289.pdf Page 35 (4-4) You find corner speed on an EM chart by looking for the highest point. The Ps will be negative and measured in feet per second, indicating that altitude loss would be required to keep turning at that rate, G, and airspeed (energy depleting). You find best sustained turn rate by looking for the highest point on the Ps=0 curve. It is usually at higher airspeed and lower G than corner speed. As for when you should be flying which speeds, how much G to pull, and how much altitude to exchange, that depends on the geometry of the fight, your opponent's energy state, and a bunch of other factors. @Jester2138I think the point of Youda holding a sustained high speed level turn was to demonstrate what the MiG-15 would do so we could analyze its energy, not actually try to beat it. @TobiasAIncidentally, I found another F-16 EM Diagram. Take a look at how vastly different it is (and with an older engine no less) than the one you had posted. 22.5 deg./sec. sustained at Ps=0 and a 26.2 deg/sec ITR! What's going on there? So I looked into it a little more. The weights and drag indexes are different on this chart, and it's probably an earlier F-16C block that was lighter than the block 50 or 52. That led me to this (located at https://www.f-16.net/forum/viewtopic.php?t=14939 ) Honestly, this is the first time I've seen this, so please correct me if I'm wrong. The above table seems to imply that the F-16C itself has a drag index of 0, and that adding external stores increases the index, maybe just for purposes of calculating the EM diagrams. Comparing the chart you had initially posted, which is 6000 lbs heavier and with a drag index of 50, it implies that that F-16 still had 2 drop tanks on plus something else, like a couple of GBU-12's. Dunno, maybe I'm doing this completely wrong. The chart I found on the other hand at 20,000 lbs would imply that F-16 is nearly out of fuel (like 1000 lbs remaining or thereabouts?) and has no external stores. So if I haven't completely misinterpreted everything, my conclusion is that performance at sea level would be somewhere in the middle at the start of the fight if you actually remember to drop your tanks. Sustained turn rate would be better than 18.5 deg/sec but worse than 22.5 deg./sec. Here's the heavier chart again for convenience:

I'm not aware of an overlay that you can bring up currently. I believe IRL military pilots have commented that the lights on the real KC-135 are quite dim and hard to see, so most pilots refuel based on sight picture. That said, in DCS we have the limitations that come with a computer simulation, like limited field of view, limited depth perception, etc. that make sight picture a little harder than normal, so I think it would be a fair compromise to have an optional overlay, IMO.

What's the best performing KIAS for a clean F-16 at 5,000 ft? I'm assuming you mean sustained turn rate?