Source? From what I know the R-77 should be shorter-ranged than AIM-120 in most conditions barring maybe a high supersonic launch. The grid fins are draggier in the transonic region and the missiles both have very similar propellant fractions.
The tactical advantage of being able to defend without trashing the missile and firing without STT lock is so large that I’d consider AIM-120 better than R-27ER by a considerable margin.
What you know is likely derived from AIM-120Bs modeling of having a nearly 4s boost and 4s sustain time in DCS when in real life it’s closer to 1.4s boost and 5-6s sustainer. Grid fins are draggier in the transonic region but maximum range is determined by the high altitude supersonic launch parameters.
The tactical advantage of stealth (RWR) launches is nullified by being visible from any point in the map due to contrails, and the missile likewise doing the same. Reduced smoke and smokeless motor missiles still create contrails due to high velocity and altitude as well as heating from the motor burning. When the R-27ER is launched and the launching aircraft also notches… leaves the AMRAAM with nearly half the engagement range or less and plenty of time for the R-27 launching aircraft to defend the AMRAAM after the R-27ER has had the time to reach the target. The AMRAAM slinger would be forced to stop their TWS updates and notch the R-27ER to defeat it.
Which is fine, because the amraam would go active on its own and find the target, quite easily given we don’t have anything remotely considered low observable.
Source for the motor btw?
Source [15], it’s a study on the AMRAAM with permissions for publication and it has thrust profiles. Says a combustion time of 6-8 seconds and based on the profile it’s 1.4-2s burn time and 5-6s sustainer. References TO-34-16C with permissions.
Discusses AIM-120B.
By my calculations (insert nerd pushing up glasses)
The AIM-120 and R-27ER (When fired from max range of AIM-120) would yield approximately 20s of time to target left for AIM-120 when the R-27ER hits the F-16, and that is if neither cranks and continues at high speed directly head-on with each other. This leaves far more than plenty of time for the R-27ER launching aircraft to evade the AIM-120 before it even finds its’ own lock and goes active.
In a more reasonable lower altitude and lower speed scenario, say 5000m and mach 1… if both targets crank while guiding they will find similar results… of course at that altitude the AMRAAM enjoys the advantages of less prior warning due to the reduced smoke motor and TWS mid-course.
I personally find this an acceptable balance, far more so than AIM-7F vs R-27ER.
I’m not talking DCS, I’m talking the known masses of both missiles which should give them similar total acceleration. Which your own research makes more to the advangage of the AIM-120 btw compared to DCS. And max range in high altitude supersonic is not the most relevant to practical gameplay, even with bigger maps you will be in missile range before being able to exit the transonic regime at high altitude.
Smoke trails aren’t as clear-cut as a RWR spike, they can be visually missed, obscured by cloud, or unclear if you are the target. Like if you focus on long range and high altitude engagement, this is also where it is most likely that a smoke trail is not seen or not acted on.
Also multi-target engagement is a huge advantage for being able to quickly reduce enemy numbers and win the match.
AIM-120A/B is ~326 pounds (147.8 kg) (sources above)
R-77 is approx. ~385 pounds (175 kg) (Aviation Week & Piotr Butowski)
That’s a 18% increase in overall mass over the AIM-120A/B.
R-77 is 200mm wide, AIM-120B is 178mm
That’s 12% wider than the AIM-120.
R-77 is 3.6m, AIM-120 is 3.65m.
Both have approx. 22kg warhead weight.
Both accelerate approximately 4 mach over launch speed.
The R-77’s control actuator section is only about as long as the AIM-120C-5’s “SCAS” (shortened control actuator section). An advantage to the R-77 initially.
From what we can assess, more of the missiles mass is propellant, and there is more missile to go around. It is negligibly bigger (diameter) than the AIM-120 and reaches similar speeds. More boost for longer is likely going to result in better performance overall and is what I base my assessment on. If you find error in this, we can discuss the specifics.
Regarding multi-target, the AIM-54 and F-14 lacks this currently. No reason to believe it’s coming (yet) and most early Fox-3 slingers have just 2x missiles, so I don’t think that will come soon. If it does, certainly advantageous but you still need them within reach of the radar to do TWS updates and defensive targets hurt this capability greatly.
R-77’s rocket motor is not proportionately larger than AMRAAM’s. If you look at images of R-77, the motor is no longer than AMRAAM’s
225/550 = 0.41 * 141 inches = 58 inches
131/364 = 0.36 * 141 inches = 51 inches
The difference is down to some slight foreshortening that is happening in the actual image. For comparison AIM-120A’s motor is 57 inches, the +5 motor is 62 inches. So the actual increase in motor volume is only the ~25% from the increase in missile radius. The only source I’ve seen on the motor propellant mass is 57kg from CAT-UXO - Aa 12 adder r 77 missile which would approximately align with a 25% increase in missile propellant mass. End result, the R-77 does not have a significant advantage in propellant fraction.
F-14 has it from what I can tell, it’s less than reliable as the TWS can swap targets sometimes. Do you not use the cursor for radar control? Also name an AIM-120 carrier than can only take 2x missiles. All the US ones can take 6 minimum. Compatibility with both the conformal ejector launcher and sidewinder rail means that many more missiles can be carried.
I did not say the R-77s rocket motor is proportionately larger than the AMRAAM’s. I said the SCAS on the AIM-120C-5 reduces the control actuator section to a size similar to that on the R-77. This was to imply the AIM-120C-5 was able to lengthen the motor propellant casing and match the R-77’s propellant mass but in a slimmer (albeit slightly longer) frame.
The actual motor of the R-77 is approximately 58.5 inches long in the section you’re measuring based on this image (I believe from an actual manual). Found on this website.
When I measured it appears the motor is 41.3% of the overall length of the missile at the seams.
(3.6 x 0.413 = 1.4868m) or 58.53 inches.
The AIM-120A motor cutaway given by Hughes.
Both missiles have approximately 41% of their length dedicated to the motor. The math works out to a similar figure if we compare it to the R-77 based on the casing, but the internal design of the missiles differs so the comparison isn’t perfect. As mentioned, the diameter of the missile is 12.4% larger on the R-77. Propellant types and ISP also differ.
What you’re not accounting for is that the battery section on the back of the rocket motor (and the control actuators that surround the nozzle) house over top of the remainder of the rocket motor iirc. This further extends the length greater than that of the AIM-120A/B motor. Unlike the AIM-120A/B, the batteries and such were housed at the rear closer to the lattice fins which are a relatively small section in comparison to the AMRAAM as mentioned and shown.
So yes, while the physical motor section of the missile appears to be a similar length (albeit on a missile that is wider)… the overall propellant housed inside is thought to be more. The publicly known burn time is approximately 4.5-6s as opposed to the 6-8s of the AIM-120B which suggests a higher initial acceleration as well. The R-77 will most definitely benefit more from a launch at higher speeds and altitudes than the AMRAAM, and performance at lower altitudes will differ.
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The F-14 does not have multi-launch capability wherein he can actively guide via TWS towards 6 separate selected targets. He has to individually move the PIP to each target and fire, he cannot select 6 and then fire in sequence. As soon as he selects a separate target to launch a missile he will stop providing guidance for the last missile fired I think. The J-8F will only receive 2x PL-12, the Yak-141 may only receive 2x R-77 and other fighters will receive less of their Fox-3 missiles as well early on.
Your image for AMRAAM gives propellant casing of 58.9 inches though(which is longer than I thought)? And your R-77 cutaway would give a propellant length of 62.5 inches. At the end of it the R-77 is considerably heavier than AMRAAM so to match it it must have a bigger motor which it seems to have and maybe a 5-10% greater fraction. But this is not a very big difference. And R-77 in addition to grid fins is also simply bigger and therefore draggier, it’s larger mass does not make up for this.
Initial acceleration profile impact on range will depend heavily on the efficiency of both missile’s loft profiles which is virtually unknowable. AMRAAM eventually adopted a single thrust profile, but that might have become optimal as a result of changes in behavior.
AFAICT the F-14 does have guidance capability on non-primary targets. The issue is that if the track is lost the missile will not reconnect if it is later regained, so it is important to avoid locking targets with sigificant separation and sometimes the ingame radar behavior will screw you. I don’t know why you’re talking J-8 or Yak-141 WRT AMRAAM, AMRAAM specifically is almost always carried in greater numbers. Part of that is that it is a smaller, lighter missile than R-77 or PL-12/SD-10.
If the target you fired at last is still visible on TWS as a dot when you switched to the next target, it keeps the TWS track, but as soon the it disappears, you lose it. That is why a lot of players are angry at Gaijin for not fixing the TWS track hop bug, that entirely disables this, because it is so frequent.
This one is a separate bug, giving guidance for multiple targets is not added for air yet , but two spaas have it , TOR M1 and pansir S1
The AIM-120 motor is actually around 59.01 inches. The propellant casing is 667 pixels long, divide that by the length of the missile (1624 pixels) we get the number 0.4107. We multiply 3.65 x 0.4107 and get the total meters length of 1.4991, we can convert this to inches by multiplying by 39.3701.
The AIM-120 propellant section is approximately 59.01 inches, however the portion that leads to the control actuator section tapers off, leaving us with less overall propellant as that entire space is not filled. We can expect it is closer to 58 inches total propellant or even a little less.
For the R-77, the motor is approximately 58.27 inches as shown here.
Motor length of 967 pixels / 2352 pixels = (0.411139 x 3.6) = 1.480102 x 39.3701 (convert to inches) = 58.27 inches.
So the AIM-120’s true inner motor section tapers towards the end for a total of approximately 58 inches, the R-77 has unknown internal design but highly likely that it extends further towards its’ own control actuator section (smaller size).
I don’t know where you got 62.5 inches from the R-77 image. The R-77 is 12.36% larger than the AMRAAM in diameter with a similar length motor (which again, I never said was proportionally larger than the AMRAAM, only that it carried more propellant which is readily evident). The grid fins are not necessarily draggier, requiring far less AoA for small maneuvers and corrections.
We can assume Gaijin will implement an arbitrary loft profile which leaves some things up in the air regarding range and performance. We know the AIM-120C-5 added more propellant and switched to an all-boost motor of approximately 8s burn time, this is similar to the profile used by the R-77 of an all-boost motor with 4.5-6s burn time. The R-77 is expected to have higher acceleration, likely to get it beyond the troublesome transonic region mentioned for grid fins. Overall, I think the R-77 is going to have better time to target, maneuvering after losing energy due to the grid fins, and also more range at optimal firing conditions at higher altitudes… which are reachable thanks to the MiG-29 and Su-27s massive ability to climb and get speed quickly… comparable only really to the F-15 on the American side.
The AMRAAMs adoption of the single thrust profile may have had more to do with assisting the missile in high-angle off-boresight endeavors… which allowed it to do such maneuvers without totally wasting the boost phase on a maneuver. This allows it to “chase” targets that it may have been fired at from off-bore angles at closer ranges. (My theory).
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The F-14 stuff was covered by others but again I’ll reiterate the AIM-54 still being updated on targets that you don’t actively have soft-selected on TWS is a bug, among other issues it is not indicative of how multi-target launches should be done.
The point of discussing other nations Fox-3s is not so easily dismissed and you know very well why I brought them up. If the J-8F is coming with just 2x Fox-3 and if the Yak-141 is getting 2x R-77, it would be generally acceptable if those weapons performed better than the weapons of which other aircraft can equip 4-6x of (like R-27ER and AIM-7F). I know the community doesn’t like it, but this is Gaijins thought process on the matter so it seems.
You guys are also completely ignoring the increase in drag of the R-77, which is likely in the ballpark of 10-20% greater than the AMRAAM without accounting for the grid fins due to the increased diameter of the missile. It gets even worse for the R-77 if you do account for control surfaces.
The longer burn time of the AMRAAM also means it has even less drag as we know that projectiles have SIGNIFICANTLY more drag when the cavity behind the projectile is not being filled by a gas.
For example, base bleed shells (which ill point out do not actually have ANY thrust) have 20-35% greater range than standard shells of the exact same dimensions.
The R-77 is a significantly draggier missile in every way over the AMRAAM.
The R-77 is not much larger than the AMRAAM in terms of size, the caliber goes up to 200mm from 178mm…
The AMRAAM has less than a 2s booster with approximately 5-6s sustainer with significantly less thrust. The R-77 has a 4.5-6s booster only, which is similar to what they do later with the AMRAAM.
Grid fins have significantly higher drag at transonic speeds due to shock waves forming within the lattice of the fins. The drag is known as “wave drag” (for others reading who want to look this up further). At speeds above mach, the grid fins have lower drag and provide greater maneuverability than conventional tail sections like seen on the AMRAAM. At subsonic speeds they have equal drag and greater effective control than conventional fins due to their much higher angle of attack before a stall occurs. They can maneuver better at slower speeds when attempting to hit targets near the end of their flight envelope.
And at subsonic speeds, per aerospaceweb
Another important aerodynamic characteristic of grid fins concerns drag, although it can be an advantage or a disadvantage depending on the speed of the airflow. In general, the thin shape of the lattice walls creates very little disturbance in the flow of air passing through, so drag is often no higher than a conventional fin. At low subsonic speeds, for example, grid fins perform comparably to a planar fin. Both the drag and control effectiveness of the lattice fin are about the same as a conventional fin in this speed regime.
The comment “The R-77 is a significantly draggier missile in every way over the AMRAAM” is simply not true, it can maintain high speeds for longer due to reduced drag from the grid fins at high supersonic speeds. The way of maximizing it’s kinematic range is to simply launch it above mach 1.3 where it will not suffer the transsonic wave drag from the grid fins.
In short:
A 4.5-6s boost will help the missile go faster than the AIM-120 and the grid fins will help it keep that speed for longer if launched above mach 1.3. Further, the AIM-120 will not be able to maneuver as well as an R-77 when attempting to reach a target at maximum ranges because the grid fins allowing almost double the maximum AoA can help to maneuver the missile better towards the end of its’ kinematic range.
Something we should also note, the R-77 is larger and has more room for batteries. It’s been said that it has 8-9 batteries in the base after the rocket motor and before the control actuator section. The control actuator requires less power to move the servos than on the AIM-120 because the grid fins require far less torque. The maximum guidance time could be far longer than the AIM-120 allowing it to coast into targets. This is also assisted by the fin design on the mid-body of the R-77.
Considering the statee missile dimensions (200mm diameter, 3.6m long R-77 vs 178mm diameter, 3.65m long AMRAAM) the math puts the R-77 frontal area at 0.031m^2 vs 0.025m^2 which is almost 20% larger. The overall surface areas of the missiles are closer, with the R-77 at roughly (assuming a cylinder and ommiting the rear surface) 2.289m^2 vs 2.065m^2 which is just about 10% more surface area (ommiting fins for both).
Considering the rest of the drag equation to be roughly equivalent, and therefore canceling itself out, the R-77 are roughly 10-20% draggier than the AMRAAM, and as stated before, thats ommiting control surfaces and ignoring the effect of base drag that the AMRAAM gains an advantage in due to the longer sustainer.
You YOURSELF state they reach similar speeds after launch from their boost phase. Considering all known factors, its pretty simple to figure out the any advantage in propellant the R-77 may have is negligeable simply due to the drastricly increased drag.
Can you make a similar in-depth research into both AIM-7F and R-27ER? Ignore Warthunders implementation of the missiles or their performance charts. Could you take a look at their airframe and mass sections? I’d be interested in hearing your conclusions.
The R-77 has approximately 63.03 inches long area wherein propellant is stored if we do not go off the seams, and rather off the possible area filled with propellant casing.
Using the formula for cylinders to calculate total area used for propellant yields approx. 88.998m2
After revising my look at the AIM-120A propellant it seems the area where propellant is stored has around 56 inches of motor. The total area used for propellant comes out to around 74.703m2.
The R-77 could yield somewhere between 10 to 19% more propellant, reaches a similar or higher speed than the AIM-120A despite a larger caliber (albeit with reduced drag from the control surfaces).
You were not accounting for the radome shape much in the same way I do not account for the fact that the propellant casings are not perfect cylinders, but
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Essentially,
The R-77
The AIM-120
My conclusion:
The R-77 may have slightly better straight line performances, but to my knowledge did not (at least initially) have any kind of lofting profile. The all-boost motor lends itself to reaching significantly higher speeds from launch at lower altitudes in comparison to something like the AMRAAM, provided it can be launched at or near mach 1.3.
At high altitude where drag matters very little, the R-77 will likely outperform the AIM-120 due to the better acceleration, better speed retention at high supersonic, and having obviously more space for more batteries.
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As a comparison, the AIM-54A (according to this sheet) has 1224.86 m/s deltaV. The AIM-7F has 955.54. This means the AIM-54A has 28.2% more deltaV than the AIM-7F. The AIM-54A has a caliber of 380mm, whereas the AIM-7F is 200mm. This is a 90% increase in caliber. In my testing (see chart below) the AIM-54A can travel a distance of 54.97km before it can no longer chase an 1100 m/s target at 10,000m. That is the furthest it can go and remain within lethal warhead radius and successfully kill the target. Likewise, the AIM-7F can only go 37.26km in the same scenario. This is a 47.5% increase in overall distance traveled and 48.4% increase in separation distance from target where the missile was able to successfully hit it with just 28.2% more deltaV and 90% larger caliber.
Another comparison that can be made is the R-27ER and the AIM-7F. The R-27ER has 1195.38 m/s DeltaV, the AIM-7F remains at 955.54. This is a 25.1% increase in DeltaV but only a 14.7% increase in overall distance traveled (albeit limited by guidance duration). The missile had a lot of velocity leftover to hit this target, but failed to at further ranges because it self destructed. This shows how important it is to accelerate quickly and maintain a higher speed, which the R-77 can likely do.
