Operational Performance Comparison: Viper, Beagle and Stubby

[SpudmanWP]

from simulations I can tell you that isn't possible. Not the 50% increase from C-7 to D that is reported.

The GPS INS of the D allows for a much more aggressive lofting profile and will use gravity on the way down to maintain maneuvering energy. Don't forget that drag is reduced the higher it gets. I am not saying that the "50% boost" is true or even official, just that the INS changes were credited with allowing for an increase in range.

Also, the max rage depends on the launch platform (ie speed and altitude) so would be quite different when looking at say a 40k foot F-16 going 600kts and an F-22 at 60k feet going mach 2.

[sprstdlyscottsmn]

from simulations I can tell you that isn't possible. Not the 50% increase from C-7 to D that is reported.

The GPS INS of the D allows for a much more aggressive lofting profile and will use gravity on the way down to maintain maneuvering energy. Don't forget that drag is reduced the higher it gets. I am not saying that the "50% boost" is true or even official, just that the INS changes were credited with allowing for an increase in range.

Also, the max rage depends on the launch platform (ie speed and altitude) so would be quite different when looking at say a 40k foot F-16 going 600kts and an F-22 at 60k feet going mach 2.

I know, check the post I just made before you posted this one.

[knowan]

Because the meteor is airbreathing it does not carry oxidizer. For that reason it has been stated that the ISP of the Meteor motor was three times higher than traditional rockets. Since it is also a larger missile than the AIM-120 I estimated it to have a larger motor. Since it doesn't need that great of speed I figured that the long burn time would come at the cost of reduced max thrust.

Relevant image:


On a related note, this is why scramjet AAMs won't be useful compared to ramjet missiles like the Meteor; unless they are intended to be cruising over Mach 6, a ramjet gives better range.

[eloise]

yes.

Okay, for the sake of discussion I will fire up my latest stable version of my missile guidance and performance simulator. For this discussion all shots will be head on at 36,000ft with shooter and target moving 0.9M.

I will start with the standard AIM-120C-5 Motor as I know it (135lb fuel, 265ISP) and give it an 8 second burn (gives 4,470lb thrust) and a 0 degree loft. (link to the atk site is a dead link, but with it having been referenced I will accept that it was true) I will check what launch ranges result in the missile still moving Mach 1+ at impact.
0 deg loft
a 41nm shot gives a final speed of 1.01M, peak speed of 4.85M, and a final distance of 28.4nm.
5 deg loft
a 44nm shot gives a final speed of 1.02M, peak speed of 4.87M, and a final distance of 31.5nm.
10 deg loft
a 53nm shot gives a final speed of 1.03M, peak speed of 4.85M, and a final distance of 38.2nm.

15 deg loft
a 71nm shot gives a final speed of 1.00M, peak speed of 4.84M, and a final distance of 51.0nm.

20 deg loft
a 95nm shot gives a final speed of 1.01M, peak speed of 4.81M, and a final distance of 68.7nm.

The AIM-120D setup I was using was 150lb propellant, 3s boost (at 2.6:1 ratio) and 14 sec sustain with a 19deg loft. Using the above firing scenario gives a 124nm shot gives a final speed of 1.02M, peak speed of 4.92M, and a final distance of 92.5nm.

I was "calibrating" it with a 33,000ft shot from 1.02 to a 33,000ft 0.83M target (effectively the MINIZAP setup) which yielded a 111nm shot for a 1.0M finish (I was looking for a 1.2M finish in calibration)

I have some questions:
1- Why does 95nm shot has the final distance of 68.7 nm? is it the final distance when the missiles still maintain altitude above 33,000 ft?
2- Is the new burn time for AIM-120D change anything about Meteor estimation?
3- According to your estimation, Meteor with 3 degrees loft and 10:1 adjustable ratio throttle, Meteor can fly 250nm compared to 68.7 nm with 20 degrees loft. Does that mean an F-35 launched Meteor from 33,000ft and Mach 1, its missiles will fly further than AIM-12D launched by F-22 from 60,000 ft and Mach 1.7? Is the advantage of ramjet engine that significant?

Back to the drawing board. Thank you eloise for challenging my assertions and assumptions. Not only can max range drastically increase, but the range at which the missile still has high speed increases as well.

I learn a lot from your analyzing as well.

[eloise]

For the sake of discussion
Photo of AIM-120B and Meteor's booster and fuel

Capture.PNG (265.53 KiB) Viewed 27911 times

Meteor's booster is 69% the length of AIM-120B's propellant
Meteor's ramjet propellant stage (not including control valve,fuel injector, MSIU, IB-igniter) is 40% the length of AIM-120B's propellant
Because the IPS of ramjet engine is 3 times better than traditional rocket motors
=> Meteor ramjet propellant stage worth 40*3 = 120% the length of AIM-120B propellant
In total, 120+69 = 189%.
Is it correct to think Meteor is similar to AIM-120B with 189% fuel?

[spazsinbad]

Is this graphic what you wanted to achieve?

[eloise]

Is this graphic what you wanted to achieve?

Yes indeed,thank you

[sprstdlyscottsmn]

I have some questions:
1- Why does 95nm shot has the final distance of 68.7 nm? is it the final distance when the missiles still maintain altitude above 33,000 ft?
2- Is the new burn time for AIM-120D change anything about Meteor estimation?
3- According to your estimation, Meteor with 3 degrees loft and 10:1 adjustable ratio throttle, Meteor can fly 250nm compared to 68.7 nm with 20 degrees loft. Does that mean an F-35 launched Meteor from 33,000ft and Mach 1, its missiles will fly further than AIM-12D launched by F-22 from 60,000 ft and Mach 1.7? Is the advantage of ramjet engine that significant?

1 - 95 nm is the launch range, 68.7nm is the flight range for hitting the target at M1.0+. The target flew the rest by flying into the missiles.

2 - This will change everything about the Meteor estimation (thanks for the graphic, that will help)

3 - Hard to say what the new meteor numbers are going to be. The new AIM-120D numbers (using the same 36,000ft target head on at 0.9M) fired from 1.7M and 60,000ft.... have to be wrong? 210nm launch range, final speed 1.10M, Peak speed 5.75M, average speed 3.5M, peak alt 114,000ft, total flight distance 167.7nm. It takes nearly 300s to acomplish this, so perhapse onboard battery duration will be the limiting factor? Not sure what to make of this just yet.

Changed the target to a MiG-31 (75,000ft 2.5M) and the 210nm launch now covers 133nm in 190s with a final speed of 3.25M and a final closure rate of 5.7M. The fact that the AMRAAM can barely turn is effectively irrelevant at that closure. By the time the MiG driver realizes he is under attack he won't have time to change his course before being speared. And I'm seeing a tail shot on a fleeing MiG-31 from 50 nm will still overtake and hit the MiG with 1.3M closure.

[eloise]

1 - 95 nm is the launch range, 68.7nm is the flight range for hitting the target at M1.0+. The target flew the rest by flying into the missiles.
2 - This will change everything about the Meteor estimation (thanks for the graphic, that will help)
3 - Hard to say what the new meteor numbers are going to be. The new AIM-120D numbers (using the same 36,000ft target head on at 0.9M) fired from 1.7M and 60,000ft.... have to be wrong? 210nm launch range, final speed 1.10M, Peak speed 5.75M, average speed 3.5M, peak alt 114,000ft, total flight distance 167.7nm. It takes nearly 300s to acomplish this, so perhapse onboard battery duration will be the limiting factor? Not sure what to make of this just yet.
Changed the target to a MiG-31 (75,000ft 2.5M) and the 210nm launch now covers 133nm in 190s with a final speed of 3.25M and a final closure rate of 5.7M. The fact that the AMRAAM can barely turn is effectively irrelevant at that closure. By the time the MiG driver realizes he is under attack he won't have time to change his course before being speared. And I'm seeing a tail shot on a fleeing MiG-31 from 50 nm will still overtake and hit the MiG with 1.3M closure.

1-i see, thank you
2-I assume it will reduce Meteor range significantly compared to original estimation? by the way, where did you got the throttle ratio for Meteor? i saw the same figure on Wikipedia but i can't figure out where the number came from.
I want to note that the photo of AIM-120 cutaway is for B version which has 5 inches shorter motor than C-5 and D version.
3-No offense against you but i think there is some mistake somewhere. I can't imagine AIM-120 with NEZ greater than 50 nm against Mach 2.5 target. If it has that kind of capability just by being launched from MAch 1.7 -60,000 ft, then R-40 shouldn't have any issue with SR-71, hell there is no point for big missiles on Mig-31 either

[zero-one]

Question.
Does staying at mach 3 to 4 always benefit the missile's probability to hit the target?
I ask because at those speeds the 35G max turn of the missile translates to around the 18 degree ball park.
Is this enough to hit targets with great supersonic maneuverability (i.e. Typhoon, F-22). Your target can travel half as fast as you can. Its like hitting a bullet with a faster bullet.

If the answer is no and that missiles will need to slow down below mach 3 to increase their turn rate or if their speed eventually deceases to below Mach 3 simply due to excessive maneuvering, then wouldn't that make the Meteor's ramjet engine dead weight since Ramjets don't work below those speeds.

[sprstdlyscottsmn]

So, the targets turn rate means nothing to the missile's turn rate. In any event, even Tiffy and Raptor are NOT doing 18dps turns at 1.7M at 60,000ft.

What matters from the missiles point of view is the number of degrees off the nose that it needs to turn to maintain an impact trajectory. If a plane does a 90 dps turn but slows down to 200kt in the process then the change in position off the nose of the missile will change very slowly.

And as far as high speeds go, high closure rates reduce reaction times.

And as to the AIM-120D range from an F-22? Being shot from that high and that fast means that by the time the motor burns out the missile is in such thin air that there is very little to slow it down. I modeled standard atmosphere up to 130,000ft. AMRAAM is a very low drag missile due to the small clipped fins. I imagine only AIM-9X and ASRAAM have lower drag. R-40 had huge fins which means lots of drag. The problem for many earlier missile too was that they did not have processors that could handle the closure rates of a head on shot against an SR-71, and chasing a 2.5M target is very different than a 3.2+M target

[swiss]

Thanks eloise and Spurts. Very interesting.

@Spurts. So the high speed and altitude don't save the Mig-31 from modern BVR missiles. Even if the shooter is on an altitude of 50 or 40'000 feet?

[marsavian]

It didn't save Mig-25 from Iranian F-14 who found Mach 1.5 and 40kft good enough to down them with Phoenix.

[sprstdlyscottsmn]

The lower and slower the shooter, with any given missile, the worse the ability to engage a high target. A fast target head on is running into the shot, and thus helping the shooter, no matter the altitude. The only reason for the 50nm tail shot being successful was because an F-22 can launch from so high and so fast that the missile has tremendous range available from coasting in thin air. A shot from 40,000ft and M2.0 would not be successful.

Phoenix is another animal with a 30s burn time. Those launch parameters result in a missile toping out at mach 5 and going over 100,000ft of altitude as well, just like this AIM-120D shot from a Raptor would.

[swiss]

The lower and slower the shooter, with any given missile, the worse the ability to engage a high target. A fast target head on is running into the shot, and thus helping the shooter, no matter the altitude. The only reason for the 50nm tail shot being successful was because an F-22 can launch from so high and so fast that the missile has tremendous range available from coasting in thin air. A shot from 40,000ft and M2.0 would not be successful.

Phoenix is another animal with a 30s burn time. Those launch parameters result in a missile toping out at mach 5 and going over 100,000ft of altitude as well, just like this AIM-120D shot from a Raptor would.

Thanks. So if you want shoot down a Mig-31 with a F-35/Ef/Rafale to it head on.