Jump to content

BlackPixxel

Members
  • Posts

    861
  • Joined

  • Last visited

Everything posted by BlackPixxel

  1. I don't think anyone said that HPRF/MPRF ambiguity cannot be solved for most conditions. For a target only the range bins that correspond to its doppler frequency need to be checked, and there will only be a few peaks. So solving the ambiguity will be simple. But when the target is in the notch, the range bins that corrensponds to its doppler will also be full of ground return. So you cannot just search for single peaks and compare their positions over multiple PRFs unless the target really stands out due to favourable geometry of the setup.
  2. Pretty certain for the 77-1 in that video. The target is to the right (target 3 in 3d space, the one with the diagonal cross), so the missile goes to the right and UP for the loft. Without loft that indicated launch range of up to 90 km on the HUD would be impossible against a typical target.
  3. From changelog: Weapons. AMRAAM's were too easy to notch when performing a notching maneuver inside of pitbull range - solved. Improved range gate modeling for missiles with active radar sensors. Does this also affect the R-77 (also an active radar sensor missile)? Does the "range gate modeling" include the ambiguous range + doppler meassurements, which will still make it hard to track notching targets in ground clutter and not allow the target to be magically seperated from the ground by range? How can the missile itself be notched outside of pitbull range? How tight is the velocity gate now? I also think that many complaints about Aim-120 being to easy to notch come from the fact that most jets in DCS have perfect RWR without any angular error. So defeating a missile is just a matter of putting the RWR missile icon on the 3/9 line, works every time due to ultra precise RWR.
  4. The Shkval slew has this very annoying bug when using analog axis: When during the slew the direction of travel is changed by more than 90°, one of the directions of travel will be set to zero. Here is an example: I hold the analog stick to the right and the Shkval moves right. I move the analog stick in the bottom right corner and the Shkval moves diagonally downwards and to the right. Now I move the stick so that it is only downwards, and the Shkval stops moving. I keep holding the stick all the way down and additionally deflect it left and right, and the Skval only moves left and right. It does NOT move downward and left/right as it should in that particular case. Note that I do NOT center my stick, for the bug to appear it is important that the analog stick is moved along its maximum deflection. This bug is very annoying, especially when trying to track moving targets, as the Shkval will suddenly stop moving even though you are deflecting the analog stick. Attached is also a Trackfile where I just move the analog stick around, and the Shkval does not correctly follow the movement because of the bug that this post is about. I hope that my inputs can be read from that trackfile. Shkval_slew.trk Thank you!
  5. Those new R-27ER models that came with yesterdays patch are a very nice surprise! I really like the added detail. But I am not sure about the texture. They are rather dark and dirty. It looks like it got recovered from a burning weapons depot. R-73 are also quite dark. In real world images the missiles are usually rather clean and in a very bright white.
  6. You have to compare speed at certain times, or time for certain speeds. Not just overlaying the graphs.
  7. Here are the tracks for F-15C and SU-27 f15_high.trk f15_low.trk high_temp.trk low_temp.trk
  8. I have made a comparison of the acceleration at 8.4 °C vs 40 °c in a level flight at 12 km altitude some days ago. 8.4 °C: 40 °C: As you can see, the acceleration is just stretched a bit in time as it gets warmer. But the top speed stays the same. Meanwhile the Su-27 shows massive differences: 8.4 °C: 40 °C: Su-27 at warm temperatures accelerates alot slower and reaches a much slower top speed (look how the warm curve begins to show the approach of a max value with a bend, while the cold curve is growing linear at the same time.) One of them is wrong (or both are wrong). ED needs to take a look at those FM's again.
  9. Only against the AI super chaff (which somehow is much more effective than player chaff in DCS). I have yet to see an Aim-120 or Aim-54 go for chaff in probably the last year of multiplayer flying, but I recently saw an Aim-120 go for chaff against AI. I could not believe my eyes!
  10. Instead of spending your time on fairy tales you should look at actual data, such as the CFD done by Heatbur or the NASA simulations. The DCS missile is now much closer to them than before. https://ntrs.nasa.gov/api/citations/20060004771/downloads/20060004771.pdf Does't look like Mk47 is reaching anywhere near Mach 5 from a Mach 1.2 launch at 45k ft, does it? For Mach 5.0, you have to launch it from Mach 2.0 at very high altitudes: https://www.nasa.gov/centers/dryden/history/pastprojects/Phoenix/phoenixmissile.html Mk60 would of course reach Mach 5.0 under slightly less extreme launch parameters. Aim-54 is still a decent weapon in DCS, I got killed by a 95 km shot launched from 7600 m at Mach 0.65 yesterday. But don't expect it to be the super missile at lower altitudes that you saw in DCS before.
  11. The motor is not that huge in relation to the missile. Yes, the missile has a litte higher fuel per missile weight ratio than other missiles, but it also has to fight so much more drag down low.
  12. I think you are the only one who knows the missile maths, so we cannot contribute to that, only read You mean at higher altitude the rocket motors have more impulse than at lower altitudes? I wonder if that is simulated in DCS.
  13. The constant thrust in the two stages is just a simplification. So instead of having a complex curve, divide it into two sections and take the average values of those sections. According to this table, the impulse per weight of the R-27ER should be 94. So if you say that in DCS it carries to much fuel, does the its fuel mass have to be reduced while increasing the average ISP to keep that value at 94?
  14. Boost: 2.5 s with 5600 kg and 22.86 kg/s Sustain: 5.5 s with 3500 kg and 14.8 kg/s Ratio of boost to sustain thrust is a bit less than I would expect. The other simulated chart in the R-27 SAM proposal also suggests a higher boost/sustain ratio:
  15. Here is the motor configuration of the R-33 in DCS, it is close to what you read from the graphs: Boost: 4 s, 37280 N, 15.4 kg/s Sustain: 16 s, 13950 N, 5.9 kg/s So it has 156 kg of rocket fuel. In DCS the missile weighs 520 kg. What do you mean with fuel doesn't burn that way? That the fuel burn is constant in each stage (simplification of the game) or something else? Regarding the R-27E motor: Yes, the end result will not change, but it is just about getting a realistic value for the missile that is in line with the official data, and not taking some third party data and saying that the real manual is wrong. What does affect the R-27E in DCS is that because of using the third party data, the boost/sustain ratio got weakened alot, so now the missile lost its initial acceleration, meaning that at closer ranges it now takes longer for it to hit. Meanwhile the manual gives a much stronger value for the boost, and also the PDF about the proposal of using the R-27 as a surface to air missile shows a much larger boost/sustain ratio than we have right now in DCS.
  16. Here is the same with the R-33ED in DCS, launched at 10 km from 500 m/s: After 60 s it has travelled about 45 km and is down to a speed of 434 m/s. The top speed it reaches is 1065 m/s. Quite a bit weaker than your estimation.
  17. That is nice to read! I was afraid that we would really have to wait for the new API before anything would change. Thank you!
  18. You have the correct drag and motor data listed in the PDF. Use them and you are done. If the missile is then not able to hit the target in that very rare maximum range edge case, that should not even matter for DCS (ECM, targets are rarely flying like a target drone), then it should be the F-14 pilots who should be waiting for the fix. But at least in all other, much more frequent combat scenarios, the missile will perform as it should. What he have right now is a missile that overperforms dramatically in all those other situations. Just take a look at this. Aim-54A Mk47 launch at Mach 1.2, 45000ft without loft. In DCS we get Mach 5 instead of Mach 3.4. That is a massive difference, not to mention how much longer the DCS missile will keep up its velocity. The result is way to much range, especially against cold targets. It gets absolutely crazy when you compare it to the DCS R-33, a very similar missile with the same size and shape, just a bit more weight. You would expect the Aim-54 to perform better, but not by this much (level straight line shot at 1 km and Mach 1.1): When will the new API come? It could be many more years. Since the release of the module we have been told to wait for the new missile API. You are again saying that we should just wait for the fix, when HB could just insert the correct values already. We have waited long enough, and suffered long enough. It is time for the F-14 pilots to show some patience. After all, they too should seek a realistic and not drastically overperforming missile, or am I wrong?
  19. @Chizh Any comment on the R-33 drag? It seems to be to much: Or is the drag of the Aim-54 that wrong Right now R-33 gets outranged by R-27ER and even by R-40. It might have less impulse per weight, but shouldn't the much slower burn result in a more efficient flight due to lower friction? Otherwise R-27ER should also outrange Aim-54. Edit: After comparing R-33 to the Aim-54 simulated charts, it seems to be indeed that it is the Aim-54 that is completely off. R-33 is at least somewhat in line in terms of top speed (reaches higher topspeed due to shorter burntime). Still not sure if the drag is totally right.
  20. That is unfortunate to read, I expected it to be an accidental error that made it into the game. That "workaround" is not acceptable. It gives the missile totally absurd ranges. Especially down low and in tailchase scenarios the ranges we see are out of this world. I hope that this issue will be adressed in the near time. The physical values should not be bent until it works in a certain scenario, resulting in a ridiculously overperforming missile everywhere else. I really expected the Aim-54 t be somewhat authentic, being a HB missile with custom CFD and all. But now I am a bit dissapointed.
  21. Drag issues with the "big missiles" Recently the R-33 got adjusted. But after observing the behaviour of this missile in DCS it becomes obvious that something is not right here. The range of the R-33 got decreased alot. In every situation I checked it now has much less range than the R-27ER. Even the R-40R has more effective range than the R-33. As the motor thrust values seem reasonable (both burntime and total impulse are in line with some sources) it is most likely an issue with the drag of this missile. So I compared it to a very similar missile in DCS - the Aim-54 Mk47. Both have the same diameter and overall similar dimensions. The Aim-54 is slightly lighter and has slightly more fuel. So a certain advantage of the Aim-54 is to be expected. But the difference between the Aim-54 Mk47 and the R-33 in DCS is insane! The following graph shows the speed and distance travelled over time. Both missiles are launched from 1100 km/h in 1 km altitude. Both fly level without loft (Trackfile for this test is attached to this post). Both distance travelled and maximum speed show massive differences. The R-33 barely reaches Mach 1.6 while the Aim-54 happily pushes to Mach 2.9. And when the motor stops burning, the R-33 loses airspeed much quicker than the Aim-54. Looking at this result I would say that the R-33 has way to much drag, and indeed it has very different values compared to the Aim-54 in the .lua configuration. So at this point it seems as if the R-33 drag is wrong and needs to be put on a level somewhat similar to the Aim-54. But is the Aim-54 drag accurate? In this document we see some graphs for simulated launches of the Aim-54: https://ntrs.nasa.gov/api/citations/20060004771/downloads/20060004771.pdf One of the graphs shows launches from 45000k feet at Mach 1.2. For the horizontal, non-lofted shot the missile reaches a top speed of about Mach 3.4. Replicating the same scenario in DCS, the Aim-54 reaches a speed beyond Mach 5. That is a massive difference. Mach 5 should not be achievable from such a casual launch, which this site also confirms: https://www.nasa.gov/centers/dryden/history/pastprojects/Phoenix/phoenixmissile.html "These missions, conducted over restricted military test ranges, involved launching a missile from a NASA F-15 aircraft flying at speeds up to Mach 2.0, with the missile then accelerating to speeds up to Mach 5.0, depending on its trajectory before fuel is exhausted." So Mach 5 is more or less the highest speed that will be observed when launching it from a F-15 at Mach 2 in a special trajectory. Meanwhile in DCS it can be achieved from a Mach 1.2 horizontal launch with no loft at all. So to sum it up, it seems that the drag of both R-33 and Aim-54 seems off. R-33 drag is to much and Aim-54 drag is to little. The correct value is somewhere in between these two extremes. Edit: Aim-54A Mk47 also seems to have to much fuel in DCS? According to HB own document (http://media.heatblur.se/AIM-54.pdf) it should be 163.3 kg with 252 ISP. In DCS it has 170,6 kg with 257.8 ISP. The missile also performs better in DCS than HB states in their own document. Aim-54A Mk60 also has to much ISP (261,6 vs 250). Aim-54C Mk47 has correct ISP and fuel mass. 54_33_low.trk
  22. The motor of the updated R-33 is fine. It runs for 20 s in DCS, the document that I could find gives a runtime between 15 and 24 s. The total impulse of the motor is also spot on and gives 73 kg*s/kg, the same value for the real one can be found in another table. But somehow the missile still appears to perform poorly in DCS, maybe the drag is still to much.
  23. The red line goes all the way down to 0 m/s.
  24. Maybe the initial angle of 30° was not estimated accurate enough. So I put the chart into blender to get the area below the velocity line. It is 28842 cm² in my case. Divided by the length of the 60 s time (363 cm) I get the average velocity of somewhere around 420 m/s. 60s * 420 m/s is 25200 m of altitude. But in the chart we reach about 9800 m. sin(pi/180*23°)*25200 m = 9850 m So the angle of the shot is about 23° upwards. I tried recreating that in DCS by firing the ER after a stall from a cobra at the right time directly above the water surface. Here is the resulting chart: The DCS missile reaches a higher top speed, as it has a shorter burntime. It also self-destructs after 50 s in this test. Up until 17.5 s the DCS missile has a slight speed + altitude advantage. But after that the R-27ER from the other chart is leading. After 50 s of flight time the missile from the real chart has about 1 km of lead in altitude, so it has travelled more than 10% further. So from this observations it appears that the DCS missile has to much drag and the wrong thrust profile. The motor might be a bit to strong to compensate for that at least to some degree, but we also don't know about the launch condition of the real chart (upwards + turn to 23°, or directly from 23°?)
  25. In DCS it was changed to 2.5 s boost with 5.5 s sustain, so just 8 seconds of total burntime. A value that is lower than the one from the MiG-29 manual (8.6 s - 11 s).
×
×
  • Create New...