Operational Performance Comparison: Viper, Beagle and Stubby

[wrightwing]

Garrya,
Also, thank you. Thank you thank you thank you. I set the conditions for a MiG-31 evading immediately at 30km from the missile (I still think the missile RCS is beneath the clutter floor, but that is another topic for which I am not a subject matter expert). I realized the exact same thing was happening. So I looked into my aimpoint calculator. The aimpoint was only ever 0.1s ahead of the target, meaning it was effectively always in Pure Pursuit! I fixed it to be based on current flight time and now the MiG-31 gets hit regardless because the missile is aiming appropriately far enough ahead of the MiG.

I am so glad when people challenge my assertions and make me second guess and re-validate my formulas.

Thank you Spurt, can you please explain what do you mean with "base on current fly time"?. When you said with lead guidance logic, all AMRAAM hit Mig-31 regardless, does that also include AIM-120D launched at maximum range from a plane traveling at 1.0M at 36,000ft?
Do you think F-15 or F-16 block 60 fighting Mig-31 from BVR will end in mutual kill?, let say we ignore jamming. I wonder how much earlier R-37 from Mig-31 can reach target before it get hit in the face with AMRAAM

The F-15/16 at 36,000ft are going to be a lot more agile, than a Mig-31 at 60,000ft. Additionally, the Mig's missiles will suffer far more aerodynamic penalties (i.e. less range) against lower altitude targets, than AIM-120s flying through thin air. In a few years when the AIM-260 comes on line, the Mig will fare even worse.

[southerncross]

About mutual kill, the R-37 fired against the "low and slow" AMRAAM shooter will definitely reach it's target before the AMRAAM reaches. If I assume the AMRAAM shooter is unaware until ~5-6nm when the RWR goes off the lower altitude allows for the plane to make faster heading changes meaning it can make a 90 degree turn in ~9 seconds and then make a gentle sustained turn back into the missile and the R-37 will not be able to track, having lost too much speed and thus turn rate.

Is it a very long shot? The R-37 needs to be already slow when RWR activates, at 6M it would fly those 5-6 nm in something like 6 s.

[sprstdlyscottsmn]

due to having to fly through denser air the R-37 is down to 2.5M in a 10 degree dive. at 6nm the expected time to impact is 10.7 seconds as the target is initially heading toward the missile at 1.0M. Once the target rapidly changes heading it opens up the flight time to impact rapidly.

[charlielima223]

I was not implying there was an additional reduction factor to apply, but that a flat 2D TVC nozzle like that on the F-22 has its intrinsic downsides and that they most probably played a role in the decision to use the current round ones.

IIRC the thrust loss was in the order of 3-4% (600 kgf for a 15 tf engine), I could try to find the source if you are interested.

From what I gather shape and design of the F-22s engine nozzles was primarily to keep the F-22s radar return signature at a minimum. The engine nozzle adheres to edge serration and alignment design. Remember that the F-22 engine was design before the LOAN design we see on the F-35 and others trying to emulate it.

Sukhoi messed around with a flat nozzle design

Similar to the F-15 STOL/MTD


From what i've read in places the flat design decreased IR plume but increased overall weight with a slight drop in thrust.

[sprstdlyscottsmn]

Similar to the F-15 STOL/MTD

Which were eventually replaced with axis-symmetrical 3-D TVC nozzles for the F-15 ACTIVE.

[southerncross]

Sukhoi messed around with a flat nozzle design
From what i've read in places the flat design decreased IR plume but increased overall weight with a slight drop in thrust.

That is my understanding too.

due to having to fly through denser air the R-37 is down to 2.5M in a 10 degree dive. at 6nm the expected time to impact is 10.7 seconds as the target is initially heading toward the missile at 1.0M. Once the target rapidly changes heading it opens up the flight time to impact rapidly

Wow, if this applies to any AAM (being defeated with a detection range of just 6 nm), it looks like they are pretty much useless Is this limitation specific to R-37, being a missile specially intended against big targets?
The target plane now turns ca. 10x faster than the estimated turn rate of the MiG at 20 km, what is the altitude and plane if I may ask it?

[garrya]

The target plane now turns ca. 10x faster than the estimated turn rate of the MiG at 20 km, what is the altitude and plane if I may ask it?

I think F-16 at 35k feet

[sprstdlyscottsmn]

Garrya is correct.

All missiles slow down more in dense air, but yes the R-37 being built to kill AWACS and the like simply lacks the ability to hit a medium altitude fighter from a launch range of 145nm. Only the Meteor stands a chance at that range.

[garrya]

Sorry, I was looking at when the MiG began evading a missile launched from 1.4M at 49,000ft only when I said that. That said, checking a 30km detection of the AIM-120 launched from 36,000ft and 1.0M from a range of 145nm and having zero delay in MiG reaction time shows that the MiG would still be hit. It's close though.

That is very surprising. I could never expect that.
If Mig-31 at high altitude can be shot down that easy by a low and slow fighter, what keep SR-71 invulnerable to Mig-25 and similar interceptor?. The gap in speed between them seem closer?

About mutual kill, the R-37 fired against the "low and slow" AMRAAM shooter will definitely reach it's target before the AMRAAM reaches. If I assume the AMRAAM shooter is unaware until ~5-6nm when the RWR goes off the lower altitude allows for the plane to make faster heading changes meaning it can make a 90 degree turn in ~9 seconds and then make a gentle sustained turn back into the missile and the R-37 will not be able to track, having lost too much speed and thus turn rate.

Assuming they are both high and fast, how far AMRAAM from Mig-31 when R-37 reach F-16?
The best counter against Mig-31 seem to be launch AMRAAM then dive down to lower altitude as fast as possible

Garrya is correct.

All missiles slow down more in dense air, but yes the R-37 being built to kill AWACS and the like simply lacks the ability to hit a medium altitude fighter from a launch range of 145nm. Only the Meteor stands a chance at that range.

Is that due to larger wing surface?. IMHO, R-77 and R-37 have nearly the same wing area

84DD1834-3598-496F-B19C-7CD1FC8B2706.jpeg (86.34 KiB) Viewed 23887 times

[sprstdlyscottsmn]

In line answers in bold

Sorry, I was looking at when the MiG began evading a missile launched from 1.4M at 49,000ft only when I said that. That said, checking a 30km detection of the AIM-120 launched from 36,000ft and 1.0M from a range of 145nm and having zero delay in MiG reaction time shows that the MiG would still be hit. It's close though.

That is very surprising. I could never expect that.
If Mig-31 at high altitude can be shot down that easy by a low and slow fighter, what keep SR-71 invulnerable to Mig-25 and similar interceptor?. The gap in speed between them seem closer?

because the SR-71 flew WAY higher and faster and the MiG-25 never had a missile in the same league as AMRAAM. Look up information about the R-40 and it's closing velocity limits. Electronics were too slow for a head on shot and the missile was too slow for any other shot.

About mutual kill, the R-37 fired against the "low and slow" AMRAAM shooter will definitely reach it's target before the AMRAAM reaches. If I assume the AMRAAM shooter is unaware until ~5-6nm when the RWR goes off the lower altitude allows for the plane to make faster heading changes meaning it can make a 90 degree turn in ~9 seconds and then make a gentle sustained turn back into the missile and the R-37 will not be able to track, having lost too much speed and thus turn rate.

Assuming they are both high and fast, how far AMRAAM from Mig-31 when R-37 reach F-16?

I don't have my sim with me so I can't check right now

The best counter against Mig-31 seem to be launch AMRAAM then dive down to lower altitude as fast as possible

yeah, more or less. That is a defensive BVR tactic against any aircraft, but just a MiG-31

Garrya is correct.

All missiles slow down more in dense air, but yes the R-37 being built to kill AWACS and the like simply lacks the ability to hit a medium altitude fighter from a launch range of 145nm. Only the Meteor stands a chance at that range.

Is that due to larger wing surface?. IMHO, R-77 and R-37 have nearly the same wing area

84DD1834-3598-496F-B19C-7CD1FC8B2706.jpeg

perspective is lying to you. the body diameter of the R-37 is 90% greater. The frontal area of the body is 3.6x that of the R-77.

[garrya]

because the SR-71 flew WAY higher and faster

In our example: the shooter at 36k ft, Mach 1 while Mig-31 staying at 75k ft, Mach 2.5
The gap in altitude and speed is 39k ft (11.88 km) and 1.5 Mach.

When we compare SR-71 and Mig-25, SR-71 max out at Mach 3.2-3.3 at an altitude of 26.2 km (86k ft). Mig-25 red line at Mach 2.83, max altitude is 23 km (75k ft).
The gap in altitude and speed is 11k ft (3.3 km) and 0.47 Mach

IMHO, the gap between Mig-25 and SR-71 is only 1/3 as big.
SR-71 envelope

Mig-25 envelope

Mig-25.PNG (357.73 KiB) Viewed 23793 times

and the MiG-25 never had a missile in the same league as AMRAAM. Look up information about the R-40 and it's closing velocity limits. Electronics were too slow for a head-on shot and the missile was too slow for any other shot.

I found the references, you are right but I am surprised that R-40 can't overtake SR-71, it is a big fast missile launched from a fast aircraft. I would expect it has an easier time overtake SR-71 than AMRAAM overtake Mig-31.

Assuming they are both high and fast, how far AMRAAM from Mig-31 when R-37 reach F-16?
I don't have my sim with me so I can't check right now

Please help me check when you get home

[ricnunes]

That is very surprising. I could never expect that.
If Mig-31 at high altitude can be shot down that easy by a low and slow fighter, what keep SR-71 invulnerable to Mig-25 and similar interceptor?. The gap in speed between them seem closer?

My 2 cents on the subject/question above:
- I agree with sprstdlyscottsmn that the culprit (or one of the culprits) here on the Mig-25 part is or may be the R-40 (AA-6 Acrid) missile.
To start with, the R-40 maximum range was quite short for modern standards. The Radar guided version (the version that allowed longer engagement ranges), the R-40R had a maximum range of 50km (which is a little less than 27 nautical miles).

Next and like sprstdlyscottsmn said, the missile's electronics (as well as those on the Mig-25 itself) were "limited".

Than the missile (R-40) was designed to engage targets flying at a maximum speed of 3500 km/h while the SR-71 could fly at speeds up to 3540 km/h which is even a bit higher than the higher/maximum engagement threshold when it comes to target speed.

The data above comes from here:
https://web.archive.org/web/20100819134 ... v/r40.html

The translation to English is below:
https://translate.google.pt/translate?h ... 2Fr40.html


Now I believe that with the Mig-31 armed with R-33 (AA-9 Amos) things would/could be different. For instance the R-33 range is more than 100km which means that it's more than the double compared to the R-40.
The Mig-31 has also a much better and more powerful radar compared to the Mig-25 and the R-33 electronics should obviously be much more advanced than those of the R-40.
But if we notice, during this time/era the SR-71 (when the Mig-31 was in service in the 1980's) the SR-71 never directly flew over enemy territory and its mission profile dictated flying alongside the border (often the West/East German border) and using standoff sensors such as SLAR (side-looking airborne radar) in order to gather intel.

[southerncross]

@Spurts: thanks for the info

[sprstdlyscottsmn]

[

Assuming they are both high and fast, how far AMRAAM from Mig-31 when R-37 reach F-16?
I don't have my sim with me so I can't check right now

Please help me check when you get home

First, ricrunes is dead on in his assessment above. It's not about the speed difference between the two planes, it is about the absolute speed of the SR-71 and the inability of the R-40 to engage it. As he pointed out, once the MiG-31 came online SR-71s were effectively stopped.

Now, on to the question of who can reach who first and by how much. Let's start with the assumptions.

Detection:
Zaslon-M locks a 7m^2 target in a jamming free environment at 105nm.
SABR locks a 35m^2 target in a jamming free environment at 87.3nm,
If we are being honest, no one here is taking the 150nm shot, that is only going to be Eagle vs Foxhound. Here, Foxhound gets first shot.

Launch points:
We are going to ignore time to accelerate to launch point or fuel burned by the launching aircraft as this is a missile timing discussion. The MiG-31 will be at 2.5M @ 75,000ft. F-16 will be at 1.4M at 40,000ft.

Evasive maneuvers:
We will allow the Zalson-M to detect the AMRAAM from 18.6nm and the SABR to detect the R-37 from 14.9nm. (less powerful radar but much larger missile.) MiG will execute a 1.3 dps turn (up from the MiG-25s 0.85dps turn to account for the vortex chines) while decelerating at 0.5G. F-16 will execute a 6dps turn while decelerating at 0.6G. Both will attmpt to execute a 60 degree turn away and then a sustained turn back at half the original turn rate to keep radar lock.

I will have to come back to this to re-run the scenario, I am out of time.

[gta4]

The impact on thrust of flat nozzles:

Check AIAA report AIAA75-1317 and 76-626.

flat nozzles drastically reduces drag of the aft body.

If we compare the difference (thrust - drag), the flat nozzle is superior from Mach 0.8-2.0, compared to cylinder nozzle.

Remember, it is the difference (thrust - drag) that determines aircraft performance, not thrust alone.

@spurs: leave me an e-mail address and I will give you more comparison on thrust and drag, for different TVC nozzles.