How’s ~.001m^2 work for you?

Is this based on the golf ball statement or sourced from an actual analysis you can cite? And even assuming that number was right, which range of figures qualifies as LO and which as VLO?

See the classification as VLO. 🙂 even the congress says its VLO so that kind of settles the argument in another thread whether its LO or VLO.

Well, an American size “S” piece of clothing would be a German size “M” and an Italian size “L”.

I prefer numbers and SI units to fuzzily defined category labels. 🙂

Why does it matter than Britain can’t buy F-22s? If certain individuals are to be believed they’re already buying a better aircraft. 😉

sferrin,

I think the “better” aircraft in this context might apply the same way Israeli electronics on the F-35 would be “better”: Better in its systemic position and fitting, for a variety of reasons not immediately related to raw performance.

One on one, I’d bet my money on the F-22. But looking at defense budgets, required width of operations, and expected adversarial forces, the Eurofighter might be “better” for its user countries. No matter how good a single plane is, you are always going to need a specific number of them to cover a theater. And if the plane is too expensive to accommodate the necessary numbers in your given budget, it’s just not an option.

Other than that, I found the article by Mr. Kopp unconvincing. One single source given during all his wild claims, with a sole foot note. He doesn’t cite cost sources, performance data sources, or even political sources for his characterization of future Russian geopolicy. Also, the notoriously difficult and fluctuating effectiveness of electronic warfare and support structure is completely put aside in favor of just kinetic performance and radar range versus detectability.

Given the way Kopp treats the F-22, I wouldn’t let him near one in a dark room and with a tub of lube in his hand.

Using your analogy, AESA is like wearing protective glases. One can throw sand, it won’t stop you from see him.

That depends on just how hard somebody throws sand at your glasses or how much he can dump on you at once. 🙂

-the AMRAAM isn’t aerodynically limited to M4. M4 is a vanilla number.

What is it limited to then?

-while this discussion isn’t specifically about the AMRAAM, it’ll help in understanding how launch speed can play a big role on missile kinematics(i.e. the missile will have a higher top speed if launched at a higher speed and altitude).
-it also points out how air density/drag at 60k feet is half that of 40k feet, which also contributes to the extended ranges.

http://www.f-16.net/f-16_forum_viewtopic-t-10195.html

I’ll look into that link later. Off to an Oscars-viewing party.

There’d still be a considerable kinematic advantage even against a M.9/50k feet launch(or a M.9/60k feet launch for that matter).

How do you come to ‘considerable’? What is your numerical definition of ‘considerable’? ‘Considerable’ is PR-speak again. I should know. I have used it often enough myself for this purpose. It’s in the same vein as ‘significant’. Or ‘appreciable’. Or ‘satisfying’ and ‘gratifying’. White noise used to obfuscate the metrics at its base.

And, I have repeated it throughout the thread a few times now: I already know height and speed make a difference. What I want to know is how big that difference is in numbers.

Point taken. But even under these circumstances no one would fire an AMRAAM on the very border of its flight envelope in order to utilize kinematic advantage. A behavior like that was observed in Ethiopian-Eritrean was and resulted in catastrophic efficiency of R-27R missiles. 😉 F-22 would most likely approach to within 40km range and then execute a shot with much larger kill probability.

I’m not sure about that. I would expect most pilots to fire as early as possible, either sending the opponent on the defensive or landing a hit if the opponent continues ploughing ahead and does his own to keep hit-probability high. If that fails, a high-Pk second shot would still be available.

If this was standard procedure, it’d also explain wildly varying Pk claims regarding the AMRAAM. While Pk technically might be 0.99 for a target properly in range, tactical application could drop that number down low, without it being the missile’s fault, if the targets actually do choose the defensive option.

And usually they should not run out of missiles either, looking at historic rates of how many missiles are statistically fired once it comes to an engagement, and how many can be and are carried on fighters.

Basically how much thrust the motor can provide for how long and is expressed in lb seconds. It can be used to quantify the total impulse available or the engine/fuel efficiency. For example 265 ISP (meaning 1 lb of fuel can produce 265 lbs of thrust for one second or 1 lb of thrust for 265 seconds or some other combination that adds up to 265) is pretty decent for a solid motor such as those on the Shuttle. 311 is pretty good for RP1/LOX and LOX/LH2 getting 450+. Where it’s relevant to this discussion is that a rocket motor has to fight atmospheric pressure (backpressure). Which is why you’ll see sea-level values as well as those in a vacuum. The SSME in the Shuttle is something like 379 at sea level and 429 in a vacuum. Different engines might have different ISPs with the same fuel as well because of their design efficiency. An RL10 with a big nozzle extension might hit 479 ISP with a LOX/LH2 combination. This is also why torpedos that use internal combustion engines tend to slow down at deep depths because the motors have to work harder to expell the exhaust products. An AIM-120 at 60,000ft will have to fight against less back pressure so in addition to benefitting from less drag it also gets more power out of the same motor.

Ah, good to know. Thank you for the explanation. Got any ballpark figures at hand for the AMRAAM? Any estimates for sea level, 40k and 60k?

Satorian, I will try to find time to post something more sufficient tomorrow. But the intial boost phase of the relavtively short burn time on a missile like AMRAAM will be affected by alot more drag if launched from an aircraft down at 40kft as opposed to one approaching 60kft. The aerodynamic drag could be up to 3+ times larger from the fact that the air density is +- 3 times greater at 40kft. This would limit the 40kft the missiles eventual top speed and altitude by a significant margin in comparison to that of the 60kft missile; since aerodynamic drag in these launch conditions for the duration of the burn time does not come close to the force needed for the missile to reach terminal velocity – therefore launch conditions can signifcantly alter range (hence why we see multi-staged rockets for heavy payload space flights). And as you point out the extra impluse adds a qualitative range advantage.

Speed converts into Altitude alot quicker for an aircraft that starts an engagement at Mach 1.7+ vs one at Mach 0.9. If this engagement starts at 100 km away, where an F-22(without stealth “VLO”) is at Mach 1.7-1.8 40000ft and the other (F-16C) is at Mach 0.9 at 36000ft heading for the Raptor. The F-22 punches in afterburner and climbs while maintaining Mach. The F-16 takes 2 minutes to reach Mach 1.75 (ignoring thats only possible with 2 IR missiles) from Mach 0.9 with no altitdue gain. Yet since we assume they both have standard AMRAAMs (with an arbitary range of 50 KM head on yet the F-22s missile is extended in range by 20-25 km by virtue of greater KE+PE) the rate of closure then means the F-22 launches the missile after 30-35 seconds 75 – 70 km away – meaning the F-16 has only accelerated to +- Mach 1.12 – 1.2. After this the F-22 cranks and disengages, maintaining a high supersonic speed – while the F-16 has yet to even achieve a firing solution that would have occured at a seperation distance of 50-55km.

I understand the combat significance as far as the qualitative difference is concerned. I still do wonder about the numbers though, especially as far as range is concerned and the constants of an already given speed determining range are considered. One thing I have difficulties coming to terms with is the missile speed. The AMRAAM for example: Does it top out at its maximum velocity (let’s assume M4) because it runs out of fuel–and could theoretically reach higher speeds–or because its aero drag at that speed can’t be overcome by its thrust? And how long does the AMRAAM need to get up to speed? How long is the burn phase? And what would be the timing differential in acceleration to top speed between the launch platform going M0.9 or M1.6?

I find it somewhat frustrating not to have proper numbers to work with. Because without some substance to the quantitative evaluation, it all leaves gaps too large for my taste.

Here is an interview with Paul Metz, F-22 Chief Test Pilot:

He says that a missile launch at M 1.5 vs M 0.9 increases the range of 50% at any given target, but also needs an altitude advantage.
IIRC that altitude advantage was 10.000 ft, but i’m not gonna scan the entire internet to prove it.
I think it’s a 30% advantage at same altitude.
http://www.codeonemagazine.com/archives/2000/articles/oct_00/f-22/f22_1.html

The article does not state the assumed height difference in numbers. 60k/M1.6 versus 0k/M0.9 (with an added long gliding path) could be a very different game from 60k/M1.6 versus 50k/M0.9. In terms of PR-speak, this leeway is very convenient, and therefore makes me wary.
If you are not going to source your other numerical assumptions, that’s OK (it’s not your day job afterall), but I’m going to remain undecided on that particular statement and its conclusiveness.

Are there any simulation packages where these numbers could be crunched? Any Matlab libraries? Any ADAMS packages?

Consider the altitude difference. It isn’t just that it’s higher so it has more potential energy to work with, the air is also thinner up there (less drag) and pressure is less (more ISP from the motor).

Sadly I have to expose my ignorance here: What does ISP mean? 😮

As for air density, how does that affect ramjet designs for example?

The thing that interests me most about quantifying kinetic advantages is how increases in the missile’s inherent kinematic dynamics, by means of propulsion and flight characteristics, relate to launch platform kinematic capabilities. And, of course, wondering which offers the best bang for the buck.