5 ms·
1. The plane has to fly sufficiently fast (to avoid stall), and sufficiently slow (to avoid "Mach tug"). As one flies higher (air density sinks), these two spee
by FabHK 8y ago
1. The plane has to fly sufficiently fast (to avoid stall), and sufficiently slow (to avoid "Mach tug"). As one flies higher (air density sinks), these two speeds converge, forming the dangerous "coffin corner". Now, in general, planes don't fly as high as possible, I'd say, so that there is some leeway in terms of chosen airspeed.
2. For given airspeed, the plane flies less time with a tailwind than a headwind.
So, this does save fuel, I'd think.
- foobiekr 8y agoYou have a typo here (it's "Mach tuck").
- FabHK 8y agoOh thanks! I seriously always read it as your nose being pulled/tugged down...
- asteli 8y agoReading your comment, I thought "how bad is a high-altitude stall anyway? it's obviously undesirable, but what makes it dangerous? possibly entering a flat spin?" Doing a little digging, it seems that there's also a significant risk of entering an overspeed condition during recovery, and inducing a structural failure! Makes sense considering that we're talking about speeds near Mach 1 to begin with.
- pdx_flyer 8y agoAir France 447.
- asteli 8y agoThat's... a bit different? AF447 is a classic case of human factors in aviation accidents. The stall would have been completely recoverable if the pilot had nosed down.
- pdx_flyer 8y agoTrue, but it started as a high speed/high altitude stall and ended because of poor pilot choices. It was in and out of the coffin corner before the pilots realized what was happening.
- Steve44 8y ago> "coffin corner" I watched a TV programme a couple of years ago talking about this on the U2 as the speeds were only a few knots apart and also varied with altitude and other factors. The image at https://i.stack.imgur.com/Lu2Xt.jpg https://i.stack.imgur.com/Lu2Xt.jpg shows the airspeed corridor the pilots have to fly through. It's constantly flying on a knife edge.