Doesnt the missile stay supersonic %90 of the time anyway? You wont be firing it while going 200KMH
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If you’re flying at M1.2 @ 30k against a co-alt target, yes. If you’re down low after defending and lining up for a snap shot the missile is going to start subsonic and stay subsonic for a pretty long time. All of the stats you can find on those missiles are from test shots at speed and altitude. I am not sure how much WT models it but in DCS for example launching a phoenix at M0.95 and M1.05 results in a pretty noticeable increase in range as the missile doesn’t hit the Mach barrier under its own power. The R77 is a decent (at best) missile under ideal conditions but the drag fins really hamper it in a realistic launch scenario. There probably is a reason the idea for grid fins was abandoned with the 77M
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Significantly reduced drag at high supersonic, equal in subsonic and only briefly does it have significantly higher drag in transonic region. They offer significantly improved stability and AoA over traditional fins but also a much larger radar cross section.
They modeled it with the lower end of thrust values given and the lower end of drag from my already extremely conservative estimates.
If we bug report the incorrect lofting they’ll need to increase thrust or reduce drag to meet the same performance metrics which should fix the missile.
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Significantly reduced radar cross section for these missiles is the primary reason. We have gone over this already.
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For some reason I trust DCS a wee bit more than your numbers, as for the grid fins, they act like bricks at subsonic speeds, nowhere near “equal” to normal fins. I’m not even sure where you got that from
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That’s from most well sourced studies…?
They’ve been posted here several times.
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the DCS R-77 isnt a good example, its on an ancient API from the Neolithic era and is really poorly modelled as a result
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So if you are firing from Mach 1+, and you don’t care about stealth, R-77 fins are better than conventional fins?
I do recall someone posting a paper here from the early days of the new forum showing that the grid fins were lower drag than conventional fins at subsonic and supersonic speeds, but higher drag than conventional fins at transonic speeds (something like Mach 0.8 to Mach 1.1).
Also, once the missile drops down in speed and gets close to the target, it would be in the transonic region where the higher drag would allow it to maneuver better and have a tighter turn radius in the critical moments before making contact.
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İt’s russian so everyone has to bash it, because Russian engineers couldn’t realize basic drag stuff about physics so they added garbage fins, while it was obviously a design choice with a goal in mind with some trade offs
Yes, that is the case.
Additionally, unlike all of these other missiles in DCS… The R-77 hasn’t been updated in like a decade. Newer information has been learned or revealed since about its’ performance.
This is important to note. They increased maneuverability while reducing cost and complexity. They knew it would hamper transonic drag … the benefits out weight the negatives, tho.
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The argument about lattice fins has been had over and over. There is a good reason why the only 2 air to air missiles that use lattice fins are the R-77 and R-77-1.
Here’s an exerpt from a 2006 paper from NATO regarding the use of grid fins for air to air missiles:
Here is the PDF in question: Defense Technical Information Center
TLDR: Lattice fins for air to air missiles look like a good idea at first, but are actually terrible. They are however undisputed kings of drag braking devices and stabilizers for bombs/dispensers.
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It’s a good thing we reference better sourced studies on lattice fins than some simple NATO paper that itself isn’t superbly sourced.
Please read and quit ignoring;
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Grid fins have been an active area of study by NASA and the USAF for decades, there’s piles of research on it and actual operational systems(MOAB and MOP both use them). SpaceX’s F9 got changes to their grid fins specifically to reduce this exact issue. The ways they are used paint a clear picture that it’s about minimizing required hinge moment force and situations where minimizing drag is not as important.
A soviet source from 1985 that for that matter, you don’t actually highlight any specific content or provide a translation for is not an adequate response.
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There is no need to write nonsense, it was not abandoned, and the R-77 M rocket was developed because the 77-1 did not fit into the Su-57 compartment
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There was already adequate discussion on the matter, of which was done not just in this thread but others… All sources posted so far were covered and discussed. I am providing the unbiased conclusion of the sources shown. The grid fins are not air brakes. The R-77 should be superior to the early AMRAAM.
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What’s more likely?
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The r77m has planar fins because they are less draggy and more suitable for the use case (if lattice fins are so good, we’d see them in more designs, but that’s not the case
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The r77m has planar fins solely to allow use with the su57, which is nothing more than a 4.5 gen prototype with what, 20 airframes in service? If space was the only reason, they could’ve used foldable grid fins instead of planar fins, but they didn’t, so point 1 seems more logical
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No need to write the stupidest nonsense. The steering wheels of the R-77-1 are folded, but not as needed. SU-57 5th generation aircraft
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