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.
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
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.
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:
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.
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.
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.
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
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
We already covered this, it is far more sensible to use missiles with a reduced radar cross section on a stealth fighter. The use of the conventional fin doesn’t necessarily indicate an improvement in missile design. In fact, it indicates a reduction in maneuverability and accuracy for the missile as well.
The Su-57 is a 5th generation fighter aircraft by all marks.
We already know grid fins to be superior for high supersonic drag. A more powerful missile would benefit more from grid fins than from conventional, this is a step back in performance for the R-77M to enhance its niche use in the Su-57.
This isn’t the place to argue this. The numbers you’re quoting are for the PAK FA prototype patent which was leaked, the actual RCS is likely far lower and the production aircraft saw major redesigns after the Indians left the project. What we see in low rate production currently has a myriad of obvious visual changes to the design that greatly enhance radar cross section performance.
The Su-57 by all means, is a 5th generation stealth fighter. Let’s move the discussion to DMs or elsewhere if you have anything further on it… Let’s keep the discussion about the R-77.
The R-77M using a lower RCS fin design is a by-product of Russia’s shift towards stealth fighters. Nothing more.
No, just R-77-1 does not fit into the Su-57 weapon bay, folding fins they would complicate the mechanism and reduce reliability. And have much more RCS what classic fins…
