E-M

There is no fighter out there that can sustain a 9g turn indefinitely. I fly F-16s, and we can sustain a high g turn better than just about any aircraft in the world, including the F-15. In a clean configuration going into a max g turn at 500 knots in full afterburner, we can only sustain 9g's for a few seconds, then the g's rapidly begin to bleed off as your airspeed decreases. Like someone mentioned above, your instantaneous g will be much higher than your sustained g. Some fighters, have very good instantaneous turn rates, but crappy sustained rates (delta wing aircraft are like that). Others are terrible in both rates (Mig 23 and 25 for example). The F-16 is good in both regimes which is why it generally has an advantage over most fighters in a turning fight.

It is important to note that no US pilot is allowed to do BFM at or below 5000' in training. 5K' AGL is the floor for training BFM in USAF and is the same or higher for the other services. So BFM engagements usually start at 18-25K' depending on the elevation below the airspace. So when you hear a USAF pilot talking about what the jet can sustain in BFM they are talking about the 15 and 20K EM diagrams like the one above. Clearly many on the forum do not know how to read one so a little primer before I go on.

The lines going from lower left to upper right are turn radius in feet. The lines curving down from top left to lower right are G (load factor). The dark and dashed lines that go up from lower left, peak in the middle, and then descend down the right side are the aircraft performance envelope. The left most dark line is the lift-limit line describing the maximum aerodynamic performance of the jet. The upper right descending line is the G-limit line (notice just over 9 Gs). The lines in between are called P-Sub-S lines (Ps) and describe the energy sustained or lost for the given airspeed and G with solid lines indicating Positive Ps (gaining energy) and the dashed lines indicating Negative Ps (losing energy). The bottom scale is obvious as Mach and CAS. The left scale is turn rate in degrees per second. This is a F100-PW220 diagram. I don't recall the differences but I know the Big Lip Blk 30 has better Ps than this (sorry Gums it's better than the A-model). Suspect Blk 50 is too. The F-18A-D is not as good. Don't know about SH. This is for level turn. Climbing or descending turns change the situation.

So looking at the diagram you can see where the quoted USAF pilot is coming from in that at all speeds at 15K in a level turn the F-16A PW220 is in a negative Ps situation and will lose energy. It will slow down at 9G till it gets to about 420 KCAS at which time the aerodynamic limits (AOA limiter in this case) take over from the G limiter and the G drops off down to about 8 G at 350 KCAS and if he keeps pulling max aft stick it will continue to slide down the aero line to about 150 KCAS where it hits Ps zero. If starting at 450 KCAS the jet will be doing an instantaneous rate of about 18 increasing to almost 20 at 420 CAS, holding that till about 350 CAS then dropping off rapidly to just over 10 at 150 CAS. An impressive average turn rate but not the way you would actually turn unless you were defensive against a really capable adversary and, even then, not the best way to respond. Defensively you would max perform the jet till you knew a missile was no longer on the way. This was usually a max performance break turn but not in AB so you slowed down a lot. But 18-20 degrees per second and chaff/flares quickly decided the matter...either you were dead or the adversary comes off to maneuver for a follow up shot or guns. Ease off the G a little, plug in AB, and stuff it in his face. Not 9G, but right to that great plateau only the Viper has between 350-450 CAS at about 6-7 G where the Ps is zero, turn rate is about 14, and radius is 3-4K feet. You can feel it because it is light buffet as the LEFs are just barely programming. Hold that till he cashes in all his chips to get the gun shot and then use all that excess energy to jump right back up to about 18-20 degrees per second, make him overshoot, and reverse to kill.

If offensive, accelerate to the turn circle, go right to 9G to get an impressive circle entry from 500 CAS down to about 350 CAS in AB averaging 18-20 degrees, then same thing. Ease off to the light buffet (6-7 G at 350-450) to herd him around the sky and when he cashes in, you have more, modulate the throttle, vary between lead and lag to get to his control zone, and gun his brains out.

None of this takes into account the vertical component that you use to your advantage to maintain or expend energy as you need to to accomplish your offensive or defensive objective. (kill or survive)

Neutral engagements are mostly like the offensive set up as you expend energy to gain a positional advantage but go to preserve mode in between to maximize performance versus energy loss. The dumb pilot pulls on the pole till he is at 150 CAS and out of options. Flying a Viper or a Hornet.

If you overlay this EM diagram with other jets like the Hornet you will see their impressive nose rates as G/aero spikes to high turn rates but even higher negative Ps. So they have one good turn and then they are slow ducks. The smart pilot flying these jets knows the same strategy I described above and only uses that for specific advantage gain and then goes to energy conservative modes. But the F-16 has what we call a Plateau not a spike. See how the Ps lines level off in the 300-500 CAS range? No other jet has such a large region of high performing yet preservative capability. They have spikes. That is how an F-16 wins and a poorly flown F-16 loses. Yes, sustained 9G at 5K is possible, but not at 15K. Deal is, your adversary is up there with you feeling the same loss of performance and usually more loss than the Viper.

I have heard much about nose pointing with new HOBs missiles. I caution the FNGs that simulated missiles in training BFM using shot criteria is a lot different than real missiles in real situations. Cashing in all your energy to get the quick kill when the missile might not produce expected results is dangerous. If WSEP results are showing that kind of Pk then go for it, but fighter pilots who live to be old fighter pilots usually will not put all their eggs in the Pk basket of one missile. Early on fighting the Hornet in the late 80s they often called kills with AIM-7 and AIM-9M at very high AOA and lots of look up as they would be below the Viper, out of speed, but able to get a vertical auto-lock with their radar and shoot. Later WSEP proved these shots were very low Pk as the missile pitches into the relative wind and exceeds gymbal limits for the missile. Obviously AIM-9X and newer missile with TV will be better but till we have lots of shots in those regimes I wouldn't bet my life on it. Never flew against the MiG-29 but always wanted to see all the WSEP type shots to prove the missile could really do what the HMS and tone seemed to imply. To my knowledge no such massive shot testing ever occurred on those missiles. So SLEM all you want but till I see the data I'm not expecting most of those shots to be effective.

Like Gums, the old guy opines. Take it or leave it. JB