Really? So with the same drag as the AIM-7F and a lighter missile, it has less than 20km of range on the deck, as the graph shows?
I was primarily concerned with the maximum launch ranges of the graph, but you’re right. The bottom end seems to be far from accurate. There’s simply no feasible way the missile has such low range at that altitude. If you have better information for me to plug in and test please share so we can further our discussion.
I mean there is a very obvious answer- the missile has bad transonic drag and it spends much more time transonic in thick air at low altitude.
The missile acceleration would allow it to exceed mach ~2s post-launch even from 0 launch speed. The thrust to weight is far more than sufficient to overcome wave drag as well, so I think this is more of an error on the part of Karpenko.
It’s possible either the source is wrong, in which case, don’t use it, or your understanding of how the grid fins effect drag isn’t 100% accurate.
Karpenko doesn’t list any launch parameters and such for his source. He only indicated that the missile has a maximum range of 100km . When I was first passed the source it was inferred that it was a primary source. Now we know better, it is not well cited. Regardless, other better (and primary) sources gave me sufficient information to model and test the missile outside the parameters wherein wave drag would have some bearing on the performance of the missile. In these conditions, we can easily show the missile is capable of exceeding 80km range. In fact, if the missile was launched at higher speeds at a higher altitude target it would be more than capable of exceeding the 100km range estimated by Karpenko.
Drag can be a huge factor at low altitude, making missile acceleration much slower, and the transonic impact of grid fins extends well above Mach 1, starting around Mach 0.8, peaking at about Mach 1.15 and then falling off slowly. R-27ER from what I know doesn’t exceed Mach 3 from a low-altitude launch, and I doubt R-77 significantly exceeds Mach 2.
So the instant a source starts to indicate something you don’t like, you turn against it. Wow, such integrity. Shall I also point out that the brochure DracoMindC used to get estimates of impulse gives the launch range of R-77 as 60/20km(presumably head/tail aspect).
In general the biggest advantage of grid fins from my research is not drag at any speed, but rather the reduction in control moment forces allowing for less powerful servos. Which would align with the R-77 having a smaller aft control section.
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I’m not tossing sources I don’t agree with. If that’s what you think, please show me a better one. ROSOBORONEXPORT claims 80km range but the public data suggests the missile has more. Indeed, the in-game testing shows it is more than 80km.
It’s possible you are overestimating the battery life then.
Or underestimating the wave drag, or underestimating the base drag or a mix of all 3.
Incidentally, I was going to try to help estimate gaijins modelling of base drag by checking the Aspide 1 drag (3.5 sec burn) vs the AIM-7F drag (15.5 sec burn) but it seems gaijin has modelled them to be the same, which likely means the Aspide is heavily overperforming
Isn’t it the other way around? AIM-7F is “underperforming” but Gaijin compensated for it by giving it extra thrust.
The Aspide is configured the same (in terms of drag value) as AIM-7E-2 and both have short burn times. The AIM-7E-2 is modeled after performance charts. So it is the AIM-7F that’s out of place.
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I haven’t found a source on it, we know the R-77-1 is 120s based on the video. I’m only looking at kinematic ranges here for the most part. If there is a battery life limitation later it would be an interesting wrench to throw in the mix.
Even if you are only concerned with kinematic range, it is intellectually dishonest to not realize how much the grid fins effect drag.
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The grid fins are a well known and well studied subject, I’ve already explained how the grid fins are more aerodynamic at high supersonic speeds. In fact, the average time to target in my tests suggests the missile spends the entire flight above mach 2 which would indicate it has a drag coefficient lower than that of the AIM-7F’s in-game. I tested it with the higher drag coefficient as to be conservative, and it still performs better than expected with the public data used.
So no, there is no dishonesty. I’m asking for you guys to critique my testing and sources. No one has done this yet, instead they accuse me of being intellectually dishonest without properly reading into what they are discussing.
Very possible actually, didnt think about that
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You are. You were oh-so-happy to support the chart when it agreed with your conclusion, but now that I pointed out that the performance on the deck indicates serious drag issues, you are tossing around reasons to discredit it. It is obvious, obvious intellectual dishonesty.
Here, have an obvious critique: the missile’s average velocity will be very different from the amount of time it spends at any particular velocity. Let’s say the missile accelerates to a speed at burnout of Mach 4 at 15km, about 1200 m/s from its starting velocity of 339 m/s in 4.5 seconds. It travels a total of 49 km, about 45.5 after burnout. Treating the drag as a function of v^2 times a constant, we can say the missile impacts traveling about 340 m/s, or mach 1.15, and deccelerates through Mach 1.5 at 50 seconds after burnout, and Mach 2 at around 30 seconds. So the missile actually spends a great deal of time at speeds where the drag impact of grid fins is signficant.
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I saw sources that suggested ranges greater than 80km, it does not make sense for the missile which on paper should clearly outperform the AIM-7F (with 98km kinematic range). This source claims 100km, and was originally shown to me and referred to as a primary source. Once it was shown it was not a primary source I discarded it as a primary source. This is not intellectual dishonesty at all.
Later on, when I had found sufficient (more proper) sources to model the missile and test it in the game I did so with extremely conservative values. I gave it the higher drag coefficient of the AIM-7F, and I did not increase thrust in consideration of the reduced drag during motor burn time. Despite these drawbacks, the missile performs better than expected based on other public sources… and in fact better than Karpenko had thought as well. I imagine with the lower drag and higher thrust it will perform significantly better still. You’ll need to calculate the drag model of the missile before making presumptions on how fast it loses speed. I’d welcome the analysis.
You already knew all of this though, I’ve said as much and now you’re being intellectually dishonest. Please take this discussion more seriously, I’m not going to feed trolling any further.
He’s continuously played with sources, tried to pass of questionable sources as fact, modified his analysis of the missile, etc… all to suit the “the R-77 is equivalent to the AIM-120-C5 and can exceed 100km easily” idea he’s been set on.
Its why I’ve blocked him so I dont waste more time arguing with him. There is a very VERY clear bias towards proving the R-77 is vastly superior to what its official numbers say.
He’s even accused Rosoboronexport and KTRV of reverse propaganda, which was an… interesting… argument.
The fact of the matter is, grid fins primary advantage in drag are at speeds air to air missiles simply dont spend much time on, and having the missile kneecap itself hard in terms of drag and controlability at transonic speeds also seems questionnable as a design decision for air to air missiles. Grid fins offer hinge moment advantages which requires smaller servos for deflection at high supersonic speeds, and packing advantages which was likely the initial reason for their design as the missile was allegedly initially designed for jets which would carry weapons internally, but dont seem to offer much real advantages over planar fins otherwise.
Grid fins have been under reasearch for decades and have been used rather extensively for ballistic missiles and re-entry vehicles, both applications spending a large portion of their time at high supersonic speeds, and one of which (the reentry vehicle) likely enjoying the massive drag during transonic speeds for reentry, but have only been found (afaik) on the R-77(-1) with ALL other air to air missiles, of varying speeds and ranges adopting standard planar fins instead.
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I’m using your own data, go ahead and give me an arbitrary drag coefficient to test and justify it, we’ll see how the missile performs in that scenario.
In fact, give me multiple scenarios to test with this data and I’ll test it.
Better yet, you can test it yourself and if you’d like to know how or participate instead of trolling feel free to DM me so we can get it set up for you.