DarkFire

Yes it is modelled. I just did a very quick & dirty test. I was flying an Su-27 against 4 x F-15C's. We were all at 5,000m altitude way out over the sea to minimise and issues with ground clutter or reflections. Aspect was head-on. The AI 4-ship of F-15's were set to a close finger-4 formation which apparently means 50 metres separation. They were set up not to react to being locked by my radar. I was able to pick up the enemy group as a single target at around 100 - 120 Km. The 4-ship single target resolved in to 4 separate targets at somewhere between 85 -90Km range. It should be noted that this was WAY beyond effective missile launch range. Note that there appears to be a strange anomaly here in that the enemy flight resolved in to discreet targets on my head-down display before they did on my HuD radar target display. So, in your case, if an enemy pilot is paying attention to their HDD, which all Su-27 pilots should be doing but fewer seem to do, they may be able to resolve a flight of 4 in to individual targets at anything up to 100Km, again for a head-on aspect engagement. The MiG-29 has a less powerful radar than the Su-27 so the ranges I found would probably be reduced by anything between 25-40% if the enemy is a MiG-29. I'd say the take home is that for any reasonable separation of a 4-aircraft flight, an enemy Su-27 will be able to resolve individual targets at anything up to 90 Km, assuming head-on aspect & no ECM. This range will be less for if you're part of a fingertips formation, but if you're going in harms way you should probably be combat spread anyway.

You certainly can. The doppler notch is very much modelled. That being said, any MiG-29 or Su-27 pilot who's worth a pinch of salt won't simply barrel in towards a target, particularly after launching, but will launch & crank to help prevent doppler notching. If you're flying against one, watch carefully what the intercept angle really is, and the enemy velocity vector, and change your flight path to suit otherwise you won't notch successfully and will still be visible.

Thanks for the info. 4-7 nm. Yep, that needs to change. 4 nm should be R-73 territory.

This. The answer to this common question that ED have stated is that it's due to the set drag of all missiles in DCS. Apparently if the drag settings are adjusted to give missiles reasonable range at low & medium altitudes the unfortunate result is that they have insanely inflated ranges at high altitude. My counters to that argument would be: 1) The atmospheric modelling clearly needs tweaking in that case. Further evidence for this is the excessive speeds that some aircraft are capable of reaching at present. 2) I don't believe that if drag values were changed to make missile ranges reasonable at low & medium altitudes then we would see everyone launching from 40,000 feet at Mach 2. Sure people would do that but there are too many counters to that tactic to make it viable against anything except another high speed, high altitude, non maneuvering target. Separately I think there are issues with guidance. Maybe not so much with active radar missiles such as the AIM-120 & R-77, but certainly SARH guidance & response to countermeasures really does need to be reviewed, but ED have said that this will be done eventually. To answer the OP, empirically if you watch youtube videos made by AIM-120 experts such as the 104th guys, they're typically launching from about 10-12 nm at low altitude. Without having seen the 51st guys and therefor being able to offer reasonable comment, I can't imagine that the R-77 is a million miles away, in fact it should be reasonably close in terms of performance at those sort of ranges. So I agree with Rage that this is mostly a range / missile drag issue for the R-77.

Respectfully, I'm aware of the theoretical considerations. The attached is from page 114 of the Su-27 flight manual, describing the function of the ACS and roll rate. The ACS does artificially limit roll rate at higher speeds to limit stress on the rear portion of the airframe. At no speed / altitude should it reach 227 degrees / second.

For a standard DCS day M2.52 at 12,500m altitude is roughly 2,700 Km/h true air speed. My fuel was pretty low by that point (under 3,000Kg I believe) indicating that the wing tanks probably were empty.

No, you're entirely correct. IIRC the Su-27 should top out at about M2.35. The situation was worse in the days of DCS 2.2.x when the Su-27 would go all the way up to M2.62, or 2,770 Km/h indicated TAS. That being said, even if our Su-27 was properly modelled to max out at M2.35 it would still exhibit the extreme roll rate, which was really the point of my bug report as the roll rate behaviour was not observed in previous versions of DCS (before 2.5).

I first noticed this while doing a speed test on the AO server, but the attached track and .acmi files confirm its existence in SP. At high mach numbers the Su-27 has an insane roll rate. Test conditions: standard DCS day, no wind, no precipitation. I'm running the latest version of DCS as of 14/05/2018 with no mods installed. See the attached track: I was at 12,500m altitude (as per HUD, not F2 view) and roughly 2.52M. I instigated a full left-stick roll. Seconds later at the 11:53 minute mark I was at 227.3 degrees per second roll rate, at 12,495m altitude though by this point I'd slowed to 2.34M. The extreme roll rate dies down below about 2.2M though it's much higher than it probably ought to be at that sort of speed. The manual says that the Su-27 is supposed to achieve a maximum roll rate of 180 degrees / second at approximately 700 Km/h for a clean configuration, not at 2,490 Km/h! Edited to add: please excuse my poor control, I think my 12 year old joystick is finally wearing out :( Su-27 Roll rate test ACMI.zip Su-27 Roll rate test track.zip

Is this an issue in SP or only MP? To that end it'd be useful to know how the hit detection works in MP, i.e. if it's server side or client side. If client side there could be all sorts of issues with net code interfering with what should otherwise be solid hits. 2nd potential issue: the R-73 only has an 8Kg expanding rod warhead. Traditionally DCS hasn't modelled fragmentation, only r^3 blast effects, so perhaps it's possible for an exploding missile to be far enough away from the target airframe to deliver relatively low blast damage when in reality the expanded rods would actually have ensured a hard kill.

Sounds about right, that's pretty much what I'm seeing. I tried a similar thing with the heaviest load I could find (max FAB-500's, 2x R-73's & ECM, works out at roughly 31,000Kg with max fuel) and with that sort of load even 90% RPM was really marginal.

Yes. This is how all semi-active radar homing (SARH) missiles work, so in terms of DCS, the R-27R /ER, the AIM-7 and Magic 530 (?) on the M-2000.

No worries. Tried 15 degrees C. 87% RPM fails to maintain constant velocity in a 10,000m altitude cruise. I'll test this fully, probably in a couple of weeks when I have a bit more spare time than I do at the moment. For now, all the conclusions I reached in these threads are (obviously) now obsolete. https://forums.eagle.ru/showthread.php?t=147556 https://forums.eagle.ru/showthread.php?t=151731

Thanks, not just me then. This has made things rather awkward. Doing things like achieving an accurate TOT has become somewhat difficult because the changes have left the Su-27 with only 2 effective speeds: ~0.9M (from 90% - 95% RPM you get roughly between 09.M & 0.95M) or AB. I'm glad that engines now take in to account temperature, pressure etc. when calculating generated thrust, but it appears that maybe the Su-27 engines need a little bit of tweaking because I distinctly remember reading that real pilots use 85-87% RPM for a cruise setting, suggesting that for a reasonably wide range of operating conditions this engine RPM range generates sufficient thrust to maintain level speed at cruise altitudes, which at present in DCS, it doesn't.

Caucasus, standard DCS day.

Personally I'd like to see a FC4 module for a number of reasons: 1) Having more aircraft with PFM-level flight models but somewhat simplified system modelling is a great way to introduce more people in to DCS, which is something I'm sure we'd all like to see. More players, more revenue for ED which in turn would allow them to develop more cool toys for us all to play with. 2) This has been discussed ad nauseum, but FC is for now the only way that we'll get anything Russian that's more modern than a MiG-23 era aircraft. Personally I think this is a real shame, but ultimately ED is a Russian company who have to comply with Russian laws on military hardware. My point is, maybe the legal situation would be less complex for FC-level aircraft. 3) FC could offer a way to model more historical aircraft for which insufficient data is available to model them to a DCS module level. So, what would I like to see in FC4? 1) I think there's a good case to be made for the Su-27S to be bumped up to a Su-27SM. This would offer a modest degree of multi-role capability without getting any secret or ultras-modern gear like BARS radar. 2) I'd like to see realism parity across the current range of FC aircraft. By realism parity, I mean things like a moving map for the F-15C (which the real thing has), adjustable pressure altitude for all aircraft. Similarly all FC aircraft should enjoy PFMs. 3) Personally I'd like to see the introduction of tactical strike aircraft. The F-18 will ably fulfil this role so for variety I'd like to see an Su-24SM2 and Panavia Tornado GR1 (a GR4 would be awesome, but probably not going to happen). 4) Surprise / dream option: FC-level EF-2000.

Before I consider reporting this as a bug & do hours of testing to provide data, has anyone else noticed that engine thrust at under 90% RPM has significantly reduced since 2.5 was introduced? It used to be the case that 85% RPM was cruise throttle at pretty much any altitude, but now anything under 90% RPM cannot sustain constant airspeed at pretty much any altitude. This may be entirely realistic, I don't know, but I do remember reading that real Russian pilots use 85% - 87% RPM as a cruise setting.

I vaguely remember reading somewhere that the yellow tint is due to a conductive film applied to avoid RCS increase due to cockpit reflection, but I can't remember where or how long ago I read this, so I could be wrong.

In fairness it could be any one (or more) of a number of things: 1) Simulated aging of the canopy laminate. Laminates manufactured in the 60's - 80's do yellow gradually. 2) Some sort of conductive film designed to avoid increasing the frontal RCS of the aircraft from cockpit reflection. 3) Anti-icing film applied to the canopy.

I think the sprite overlay was useful as a training tool - it acclimatises pilots to visual scanning without relying on the (IMO) much more unrealistic labels. It was very easy to step down the size of the overlay sprites when visual spotting skill increased without having to rely on a big blue or red icon showing the location of a unit. I do agree that for MP servers the option should be under the control of the server rather than being a local setting, but there are already a pile of options that can be set by mission designers, so surely it should be possible? I'd also ask the dev team to bring it (or something functionally similar) back please.

Prediction: the most capable pilots will win. I've seen Su-25 pilots shoot down F-15C pilots who's SA was nonexistent, and I've seen plenty of A-10's shoot down MiG-29 and Su-27 pilots who had no idea what was going on around them. To a very large extent hardware is less important than the skill of the pilots.

A slightly tangential question: does DCS simulate aerodynamic airframe heating?

This. It's probably set up so that it works quite effectively using a stick that's the same length as an actual Su-27 stick, but with the typically short consumer joysticks that most of us use, it's horribly inaccurate and the trimmer buttons are a much better option.

Assuming no drastic mis-match in weight, the most skillful pilot would win. The most skillful pilot always wins.

Ah, just like the good old days :D In all seriousness, I would imagine that we'll get the modern Su-27 style dynamic AOA/G limiter at some point.

Probably working as intended. I think it's a terrain avoidance system as opposed to a full terrain following system. So, when it detects the ground at an unsafe altitude it'll pull up but then will not fly down again after the obstacle has been passed.