Machalot

The NASA paper says: So the data NASA used is not gospel and they don't stand behind it. On the other hand, in theory it should be accessible by HB to match their model, at which they have already done a pretty good job.

As far a I can tell by poking around the lua files, there is no altitude dependency of the drag coefficient, which is pretty much true to real life (IRL there is a small change in viscous drag, but that can be ignored for our purposes.) The speed of sound varies a bit with altitude which affects Mach number, but that is modeled and is not primarily an altitude effect. The main cause is that air density doubles every 15 kft you descend, which doubles the drag. So at the same airspeed, there should be about ~3x more drag at 20 kft compared to 45 kft, and ~4x at 10 kft. Does that jibe with your experience? Here's a reference for the Standard Atmosphere: https://www.engineeringtoolbox.com/standard-atmosphere-d_604.html Here's a plot showing the effect on dynamic pressure, which is directly proportional to drag.

What does this mean? In this thread there is a graph showing a good match between DCS and the NASA sim results.

Everything from the team is right, otherwise we wouldnt get this! but the question is if the team is right?! I thought we were talking about roll trim. What does 0.1G or 0.05G have to do with roll?

We're talking about a speed limit. It's just easier to exceed the speed limit at high altitude.

Also make sure you set the switches. Don't use GRUPP unless you are completely sure the ships qualify as a group as defined in the manual. Otherwise the missiles will fly right past the ships looking for a group.

Service ceiling is when the max climb rate drops below a threshold (e.g. 100 ft/min for American jets) under certain fuel and loadout assumptions. The only thing we're talking about here is that the Viggen's afterburner flames out above ~13 km. Not directly related to the service ceiling.

Consider making the Viggen self destruct of it flies above 13k. Or actually above 13m

I'm not an expert on this topic, but I haven't heard the term delta pressure in this context before. I have heard gauge pressure to describe this measurement, rather than absolute pressure.

The Viggen uses QFE all the time, including to sight bombs on target.

Can you record a video of it?

I haven't experienced this in a lot of low level flying with all kinds fuel and weapons loads. Any chance you're getting hit by SAMs?

Another consideration is that burn time is defined differently by different sources. It can be defined as the point when the thrust curve drops below say 90% of its peak, or drops below say 10% of average, or when some percentage (e.g. 90%) of nominal impulse has been delivered, or chamber pressure drops below a threshold like 2000 psi, etc. So it's not even necessarily when the thrust goes to "zero" (if such a point can even be reliably measured and is reproducible). With that in mind, some possible burntime values from the -54C curve in your graph could be 3.7, 3.5, or 3.2 sec. For a differenr missile with a 25 sec burntime that could be a span of several seconds.

This is true about the burn time, but I'm skeptical that the propellant mean bulk temperature (PMBT) would change fast enough to really respond to fight conditions. The temperature response time is typically measured in hours. I think for most DCS sorties the PMBT will pretty much be what it was before takeoff, which will be whatever it was where the missile was stored. I could be wrong for smaller missiles.

That's not detailed enough to determine the SRM component masses.

I could believe that. It appears the new Isp of both motors is only 230 s, which seems low based nothing but my own experience. If it were 250 s like it was before, that would make up half the difference. Your excerpt doesn't quote the altitude or ambient pressure for that impulse figure. Do you have an idea what it might be? I don't know the nozzle exit area, but suppose the nozzle exit diameter is half of the outer diameter of the missile, or 14 cm. That is an exit area of 0.015 m^2. If DCS inputs provide impulse at sea level, and your figures are at 40,000 ft or a vacuum, there would be an additional 1200 - 1500 N of thrust, which just about makes up the remainder.

My opinion -- not representing HB or anybody but myself -- I think it's likely the Army document you're referring to is incorrect. I put together a comparison using the HB Aim-54 white paper. Numbers highlighted in red are what I consider suspicious and not likely realistic. The data in the AIM-54A-Mk60 column derives from the document in question. Note that the Mk60 somehow fits 45 kg (27.6%) more propellant into the same volume as the Mk47. In fact it appears to claim the Mk60 propellant mass is greater than the entire Mk47 rocket motor (including propellant, insulation, case, supporting structure, and nozzle). It's not really plausible. I think it's likely the 208 kg of propellant listed in that document erroneously included the entire Mk60 rocket motor, not just the propellant mass, and that the actual masses and performance of the two rocket motors are very close as HB is modeling with this new update.

I haven't noticed that it matters, but seems like a good idea to unlock them. I'm not sure irl that they ever boresight on the ground.

Ha, I wrote the same post, with a very similar graph, and exactly the same points about induced and parasite drag, earlier today but didn't post it because I hadn't had the time to edit and refine it in between work.

Yes, generally you should not be trimming in pitch, only roll as necessary for unbalanced loads.

This is known and already in the bug tracker.

Maybe you could start by explaining what physics equation you used to get from speed (1000 m/s) and mass (10 tons) to a measure of power (100 GW).

This is nonsensical. It has nothing whatsoever to do with the kinetics of a turning aircraft. And the math is wrong.

But you really should create a new topic, by the rules and by etiquette. They are free and a new thread is much more likely to get the attention and help you deserve.

I just ran a single player mission about 9 times, testing codes 921, 922, 923, 921, 922, 923, 921000, 922000, and 923000. Each time, I set up the weapons, launched, and then watched in F6 view overhead to see the flight paths and dispersal patterns, then ejected and respawned. I didn't find anything unusual with the weapon employment. The patterns always matched my inputs. (Although after about 6 respawns my altimeter QFE setting went to 300 something, but it only affected my release queues, not weapon performance). I can provide the track if you want. But do you have a track showing that it doesn't work? Edit: Just reread your comment and I think I missed your point. You're not saying 922000 doesn't work, you're saying STD shouldn't disable it, right? I ran all my cases in VALB. So my test was probably not relevant to your post.