F-15 Inflight Emergency
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Considering all the inflight incidents involving the F15, I have the distinct impression that their days are truly numbered.
With the F22 & F35 programs being overbudget and relatively behind schedule... what are the options for the USAF?
More F16s or some F18s to their inventory?
With the F22 & F35 programs being overbudget and relatively behind schedule... what are the options for the USAF?
More F16s or some F18s to their inventory?
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Well, the legacy Hornet is out of production, and the Super Hornet is not really ideal for the USAF's air superiority needs (relatively slow top-end, poor specific excess thrust at all speeds, wrong refuelling interface, etc). New-build F-16s are expensive, and the airframe is at the end of its' development life anyways.
But more to the point, the gov is already spending barf-inducing amounts of cash on replacement fighters for the USAF. I don't see anyone ponying up a few billion dollars more to get interim replacements in the mean time.
The F-15A/B/C/D's days really are numbered, but the USAF is still in pretty good shape. There are lots of F-15Es that don't have these issues. These can do the air superiority job better than most of the air-superiority tasked birds anyways. The F-22 program is behind schedule, but IIRC something like 70+ have already been delivered. These are only flying with an IOC (and will need years of 'spiral upgrades' to deliver their advertised capabilities), but realistically if $h!t hits the fan, the USAF is at the point where it can put armed raptors in the air, which will still outgun anything anyone else can bring to the table.
So I expect to see some F-15Es re-roled to air superiority, and some F-16's upgraded to block 60 to replace them in the air-to-mud role.
But the USAF is just going to have to get used to a smaller air superiority force. MUCH smaller. There realistically never were many F-22s in the pipeline, so this has been in the cards for a long time now.
But more to the point, the gov is already spending barf-inducing amounts of cash on replacement fighters for the USAF. I don't see anyone ponying up a few billion dollars more to get interim replacements in the mean time.
The F-15A/B/C/D's days really are numbered, but the USAF is still in pretty good shape. There are lots of F-15Es that don't have these issues. These can do the air superiority job better than most of the air-superiority tasked birds anyways. The F-22 program is behind schedule, but IIRC something like 70+ have already been delivered. These are only flying with an IOC (and will need years of 'spiral upgrades' to deliver their advertised capabilities), but realistically if $h!t hits the fan, the USAF is at the point where it can put armed raptors in the air, which will still outgun anything anyone else can bring to the table.
So I expect to see some F-15Es re-roled to air superiority, and some F-16's upgraded to block 60 to replace them in the air-to-mud role.
But the USAF is just going to have to get used to a smaller air superiority force. MUCH smaller. There realistically never were many F-22s in the pipeline, so this has been in the cards for a long time now.
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Can anyone with more knowledge on flight or emerg procedures tell me what went wrong on landing? His approach speed was fairly high but with one engine that's a given because of the risk of stall, but he still went off the end of the runway. Did he make a mistake or was that just the way the cookie crumbled?
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This incident happened in 1993. I think the aircraft was engulfed in flame and the pilot just had to punch out. I suspect that very few pilots would have tried to bring that bird in considering the spreading fire. Just my take and well out of my lane here. 
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benny88 said:
The airplane will stall at the same speed, regardless of the number of engines working. The issue there is the fire spreading around. He's trying to over oxygenate it so it stops or at least doesn't spread too much. That's the reason he lands at a higher speed (he actually verbalise that in the video)
Max
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SupersonicMax said:
Oh right on, I missed him saying that. I know it'll stall at the same speed but I thought with an engine flameout the approach speed was kept higher in case an abort was called and the a/c had to go around. I never knew about the "over oxygenate" prodcedure, but that makes total sense, thanks Max.
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[\peanut gallery]
A quick look at Whiteman AFB on Google Earth shows that from where the pilot touched down, he burned through about 10,000ft of runway. A quick look at the HUD shows he managed to lose less than 90 kts during 10,000ft of run out. That means he had essentially no braking action whatsoever for most of his run-out. I think these two had just left Whiteman, and so were probably full of gas too.
From my peanut perspective it looks like he hammed on the brakes when he first touched down, because he wanted to get out of that bird NOW. My guess is that he overheated his brakes within the first 500 ft on the ground, because he had no braking power at allafter that. He coasted at over 180 kts for more than 3 km. He may have been able to stop in time with more judicious use of the brakes, but it just may not have been realistic to stop from that speed, given the winds, weight, and runway length. He DID ask for an arrested landing at a 12,000 ft runway, which indicates he knew this was going to be hairy. He may have even been banking on the cable ("Confirm departure end cable at Whiteman" .... "Negative cable at Whiteman"), and when he found out otherwise it was too late. He certainly wasn't going to do a go-around.
Or maybe I'm completely out to lunch. But he was in a crappy situation, did his best to save the bird (even though it was clear his wingman thought he should bail), and when it was clear that it wasn't going to work he managed to safely (presumably) extricate himself from the whole thing. Could have done worse. I think this was just how the cookie crumbled.
[peanut gallery\]
Just my opinion (worth what you paid for it)
A quick look at Whiteman AFB on Google Earth shows that from where the pilot touched down, he burned through about 10,000ft of runway. A quick look at the HUD shows he managed to lose less than 90 kts during 10,000ft of run out. That means he had essentially no braking action whatsoever for most of his run-out. I think these two had just left Whiteman, and so were probably full of gas too.
From my peanut perspective it looks like he hammed on the brakes when he first touched down, because he wanted to get out of that bird NOW. My guess is that he overheated his brakes within the first 500 ft on the ground, because he had no braking power at allafter that. He coasted at over 180 kts for more than 3 km. He may have been able to stop in time with more judicious use of the brakes, but it just may not have been realistic to stop from that speed, given the winds, weight, and runway length. He DID ask for an arrested landing at a 12,000 ft runway, which indicates he knew this was going to be hairy. He may have even been banking on the cable ("Confirm departure end cable at Whiteman" .... "Negative cable at Whiteman"), and when he found out otherwise it was too late. He certainly wasn't going to do a go-around.
Or maybe I'm completely out to lunch. But he was in a crappy situation, did his best to save the bird (even though it was clear his wingman thought he should bail), and when it was clear that it wasn't going to work he managed to safely (presumably) extricate himself from the whole thing. Could have done worse. I think this was just how the cookie crumbled.
[peanut gallery\]
Just my opinion (worth what you paid for it)
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If he did hammer on the brakes that hard, wouldn't the tires have gone first?
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benny88 said:
Going around when you are on fire is generally not a very good decision!
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Aden_Gatling said:
Most jets (probably the F-15 included) have anti-skid brakes. This will stop the tire from locking up, but won't stop the brakes from melting.
Keep in mind that the brakes have to absorb (as heat, via friction) pretty much all of the kinetic energy of an airplane as it slows down. Just to put some round numbers to it, to slow a close-to-MTOW F-15 from 260 kts to 210 kts (as in this case) means the brakes had to absorb somewhere around 11,000,000 J of energy (give or take). In the course of about 8ish seconds. A quick back-of-the-envelope calculation (feel free to do your own) figures that's enough to heat up your 20 kg (WAG) worth of steel and carbon fibre brakes by around 1000 degrees (minus whatever they can radiate in 8 seconds).
I'm not privy to the F-15s brake design, nor am I an accident board, but a guy touched down about 100 kts too fast, and ran right off the end of a 12,000ft runway. If he had a catastrophic hydraulic failures (in a plane with powered flight controls) he probably would've gotten out of there tout sweet. Not to mention that he had enough juice to get his gear down, and maintain flight controls. My guess is there's Flintstones-style heelprints all the way down that runway.
A
aesop081
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FoverF said:
Lets no generalize here. Not all airplanes use breaks for the majority of their "slowing down" once they hit the pavement.
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FoverF said:
Unless everything I've been taught is a lie, the vast majority of speed decay is caused by aerodynamic drag, not brake friction! Given the properties of drag, this relationship would be even higher with excessive touchdown speed. Moreover, the Brake Fluid will boil (causing a loss of braking action, as well as excessive pedal travel) before the pads will "melt." I'm not really an expert on the subject of tire wear, but if I were to force a tire to spin up from 0-250 (vice 0-150, assuming your numbers are correct; I don't know what they are for the F-15) I would be very concerned about losing a tire (or tires) and much less so about the brakes themselves (especially given that he has the arrestor cable).
My guess is that he was just too fast and ran out of runway (albeit fast with good reason).
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CDN Aviator said:
You're right, I was hasty. There's thrust reversers, landing flaps, airbrakes, high approach angles, drag chutes, etc. But in this case, the attitude and speed of approach suggest there was no flaps, airbrake or dragchute.
Aden_Gatling said:
The wing was unloaded (at a few degrees negative alpha) for very little induced drag, and as you can see in the video, without brakes and relying on aerodynamic drag alone this guy blew right through 12,000 ft of runway and barely missed a beat.
Aden_Gatling said:
"Melting brakes" was just a euphemism for a non-specific brake failure due to high temperature. I didn't mean that the pads themselves would have literally melted necessarily (although they might have), just that the brakes didn't work because of heat. At this speed he could have easily blown tires on touchdown, but it doesn't look like he did. And I'm pretty sure the controller says "Negative cable Whiteman", indicating that he doesn't have the arrestor cable .
I was never really convinced about his buddy's idea to come in hot, but I wasn't Johnny on the spot, so I'm not going to second guess the guy. He had a bad combination of high weight, high speed, the distraction of a persistent engine fire, and only one pass. Good on him for trying, and for knowing when to pull the handles.
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FoverF said:
This still doesn't make sense to me: on the ground (actually near the ground) induced drag is near zero: induced drag has very little to do with stopping an aircraft.
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Aden_Gatling said:
Ever watch a large delta land? (Concorde is a good example; BIG delta at high alpha produces big drag, ground effect or not) But you're right in that it probably wouldn't have made a huge difference here. I was just trying to point out that this guy had no airbrake, no flaps, no chute, and no angle of attack, so he didn't really have any major drag factors in his favor.
As I'm sure CDN Aviator was hinting at, this depends entirely on the airframe. An Aurora on a slow approach, with spoilers, flaps, and 4 negative pitch props at full power could probably have stopped at Whiteman without brakes at all. Yet we all saw with our own eyes just how much energy this clean (except the gear) F-15 lost on the ground from aerodynamic drag, and it was pretty close to SFA.
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aesop081
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FoverF said:
Spoilers ??
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FoverF said:
Delta wings are a moot point: they can achieve lower speeds prior to touchdown, but no wing produces induced drag on the ground roll, by definition! Here is a video of a Concorde in which you can see the vortices disappear as the wheels touch: http://www.youtube.com/watch?v=OBtLix4xqdI It is even further from the point here, as the F-15 is not a delta wing in any event.
Most of those are used to increase parasitic drag (which was my point); even on the non-reversing pitch Harvard, the landing roll is significantly affected by the position (feathered vs. unfeathered) of the prop blades.
The pilot stated that due to the fire he was landing fast (which makes sense: see Max's earlier post), and as I am certain that the F-15 has a pretty significant landing roll in optimum conditions, Occam tells me that the pilot panic / brake fail theory is an unnecessary complication to the (known) fact that he was too fast for the amount of runway available to him.
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