8/12/2023 0 Comments Aim 120 max aoa![]() Let me know if you have an actual wing loading number, we can only keep speculating otherwise. less than 31 g's at mach 1.3 and much less than what happens in the game. This in turn would mean that the expected max G at a specified Mach of an AMRAAM should also be lower than that of such AIM-9, i.e. To believe that this graph is somehow valid for both, we'd need at least their wing loadings, which for most Sidewinder variants it should be lower than that of an AMRAAM. Then there's the fact that your graph is not about an AMRAAM but refers to an unspecified AIM-9. Now, since this value is around 15% less than what happens in the game, we can say that the model is in fact overestimating a bit. ![]() The "variant" stands at roughly 25 (the line is closer to 30 but the graph is logarithmic) which is therefore corrected to 31. Rho at 3000 ft is 1.11 kg/m3 while at 10000 it becomes 0.9 therefore we can assume that your graph times ~1.23 should yield a somewhat correct value. Let's do a simple correction about the air density and your graph should still be useful. Then there's the original case: mach 1.3 at 3000 ft. The true value at 1100 kph and 10 kft according to your graph is between 10 and 12 G's which is definitely a more reasonable number. Ok, first thing first: a missile doesn't reach 40 g's at 1100 kph as you stated before, that wasn't logical at all. Reaching up to 35G at that speed is probably not unreasonable we have gloading charts available for an AIM-9 with an AIM-120 style nose cone and much smaller fins and it was fully capable of reaching its structural G-limit of 40G at speeds as low as 1100kph. After all, if this were possible, the next supersonic transport would look exactly like an AIM-120. Pulling 35 g's while still in the transonic regime is a bit silly as a number, I am sure that if there are any aeronautical engineers in your team they would agree with this straight away. Instead of being just pedantic, I'd like to ask you to give me, or the community in general, the opportunity to look into the details of your calculations, as there may be someone capable of quickly identifying the culprit (I'd be looking at the mesh, most problems are there) and hopefully leading to a more trustworthy model. The error may be subtle but is certainly a possibility, especially since CFD is not an exact tool and requires careful analysis to be trusted (I know this for a fact, having worked on CFD's myself). Now, I appreciate the hard work that you put in to come close to a high fidelity missile, but there has to be some kind of error in your CFD. And I say lower than because the maximum lift coefficient at the fast edge of the transonic regime is quite substantially lower than the incompressible value. This also means that the lowest speed at which the missile can sustain flight would be lower than 69 m/s (249 km/h or 155 mph). In fact, this value would imply (considering an empty weight of the missile of 75 kg) that the value of S*Cl is 0.25. At the moment the AIM-120 is capable of pulling 35.1 G's at 1558 km/h TAS (as the picture below shows), which is a value that makes me raise my eyebrows a little bit. My concerns are mainly about the maximum lift coefficient of the missile. Even though this has been an issue for quite some time (since the last flight model update of the AMRAAM) I have now decided to ask about some clarifications over the behaviour of the AIM-120.
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