Tbf, militaries dont need to have all the hard numbers, or really any of them, publicly stated. They tend to send bids in with the relevant info and the countries will trial the systems then pick which they want.
If anything, its weird military companies put out relevant info on the system, even if its faked to some degree. Its likely more for a stock performance and/or public perception thing.
Its inconvenient for us to try to find info on something with good opsec, but its likely better for the manufacturer and countries using the system.
As for why countries like ukraine are publishing some numbers through news orgs as seen with the below sheet, thats likely due to the fact that a lot of the aid they get is dependent on public perception in the west, so they likely converse with the manufacturer about what they are allowed to publish info-wise to boost popularity/perception of the system with western audience without it being directly from the manufacturer.
Spoiler
Primary sources will be thrown in the trash after being shipped to the russian MOD anyways. Lets not pretend gaijin cares about modelling this missile accurately, they simply dont want to believe anything beyond the idea that it sucks. Its why theyre so quick to nerf it using bad sources, but refuse to buff it regardless of what info is provided.
They quite literally actively ignored the word “laser” in primary info on the seeker, multiple times, and then closed the bug report.
It can’t, I’m pretty sure some of the boys in the server tried it out, it currently stalls out at around 12 km or so. 10 km seems to be about right from their calculation.
Oh btw, anyone enjoying the fact that when modelling the Pantsir S1, gaijin clearly went with the assumption that the 18km range stated for the 95Ya6 was its effective range, but that when modelling literally everything else, the stated range is “only for targets flying straight at you at very high speeds”?
It seems that if the missile is to only climb, it can reach 20km. But against any maneuvering (or rather fast moving) target, it will be much much lower. That 10km calculation is in itself a tad nonsensical, it assumes that the missile can not coast anymore beyond 15s, whilst flying at max speed for the entire boost duration? A lot of altitude can be gained still after the 15s burntime, coasting off it’s maximum speed (that ~M2.0) in low density air.
Spoiler
I don’t think it’s performing differntly from the missile on the dev at least. When I use this thing in a normal launch, it hits similar performance to seen on the dev (just shy of M2.0 at 15s, dropping to subsonic at 12-13km).
Also for funsies, I guess, I multiplied the SLM’s booster figures by 1.5. This gives the engine a total impulse of like 220+ kN, which lines up with the one Janes source mentioned here and more in line with one estimate made here.
With that, M3.05 can be reached and 30km travel distance is reached in 64.6s, which seems quite a lot more in-line with with reality perhaps. Not the best energy still though at those ranges still tho.
A hybrid-propellant rocket engine could: Solid fuel, liquid or gaseous oxidizer.
So it wouldn’t be wrong to say they lowered the SLMs thrust to 66% of its intended level. Then we can also assume that they increased the drag by the same margin they took from the thrust. Seems all to be way too in line to be a coincedence. They effectivly reduced all parameters (or increased in the case of drag) of the missile by one third (like the G-Overload from 60 to 40).
I’ve seen sources saying that the SLM has a dual pulse motor which can relight after coasting for a while, but it’s not even worth mentioning when the current gap between the IRL and gaijin model is like the gap between 9X and a 9B
If I lower the drag now, the effects of the thrust increase will likely make it overperform (maybe). I can play around with it a bit more and see to what single % increase (or decrease for drag) I can settle for both thrust and drag and see if it’s suspicioulsy convenient. I doubt it though, but I also like to know where the current rocket engine numbers even come from.
Also is the current weight of the SLM correct? It seems it has about 60kg of fuel right now. Idk if it’s realistic to get 200+ kN s of impulse out of that.
I don’t know where but I could have sworn to read >250 kN for the SLMs missile motor somewhere.
As I stated somwhere above, the normal rules for the rocket motor don’t seem to apply here as they don’t use a standard aluminium propellant but something that contains lithium to a certain degree (deep red flame instead of orange/yellowish).
I am not necessarily doubting the amount of impulse, but more with the current fuel mass it’s an outlier if given that 250 kN s. Right now the engine thrust seems to be tuned to be in line with most other engine performances, which is likely not correct either.
AIM-9L has 57240 N s of impulse with 27 kg of fuel, which is 2120 N s/kg
IRIS-T has 67690 N s of impulse with 38.8 kg of fuel, which gives a fairly low 1744 N s/kg
Most engines from quickly checking fall between this 1500-2500 N s/kg range
Current in-game SLM has 148050 N s of impulse with 63 kg of fuel, which gives 2350 N s/kg, which seems in line with other engines. If it was 250 kN s with 63 kg of fuel, you’d get 3968 N s/kg. Is pretty high, but honestly I am not well versed enough in rocket propellant to know if this is normal or even a valid way to compare rocket engines, by say their fuel efficiency.
*I know this measure is pretty closely related to Isp, but I think that one takes into account the entire engine
That seems awfully low? The SLM is more than 60 kg heavier than the standard IRIS-T (155 kg vs 88 kg) so it having only 25 kg more fuel is kinda… strange? Especially as the rocket motor is the only thing that is bigger (longer, larger diameter) for the SLM while everything else (guidance, warhead) has the same size as the standard IRIS-T.
Strange. Guessing from the size (two third with much larger diameter and therefore volume and half a meter more length) it should weight much more than only 22 kg more than the standard IRIS-T. Even if the propellant would be exceptionally light with 2-3 g/cm³.
Actually, now that I look at it, I think it’s just Isp what I am noting down. Just without dividing by the gravitational acceleration (say roughly 10), not completely sure if I can just take just the fuel and not the total engine weight though.
I know at least that an Isp of 150-250 is fairly realistic, 400 would be really high on the other hand, if it does use solid fuel.
The best source we have for weight does state weight between 140-150kg, and that source is a polish defense book that featured some production details, the first SLM missiles were only 152mm so those might have weighed 110kg but the ones currently in production and we have in WT are 180mm so heavier as well.
Jecka is currently ordering that book, i hope gaijin will consider it even if it’s a polish source.
And it has Mach 3 speed as well, but again we’ll have to see if it’s a good enough source for gaijin.
Edit: the website where he found it and the books mentioned in the sources
