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With Travel Halted, What Happens To The Planes?

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Brumby:

--- Quote from: WattsThat on August 10, 2020, 10:29:01 pm ---I am not surprised that both pilots mentioned had glider ratings. With that experience, one learns from your first flight that without power, you get one and only one chance for a successful landing.

--- End quote ---

You don't need to be any sort of pilot to understand that.

jogri:

--- Quote from: sleemanj on August 10, 2020, 09:26:41 pm ---120km glide over the open ocean to the Azores (and they still had to lose excess altitude!).  A good example of how airliners are more like massive self launching sailplanes than we give them credit for.

--- End quote ---

Modern jets like the A320 or the 737 have glide ratios of 15-20 (sailplanes are in the range of 50-70:1), that means they can travel 15-20 miles for every mile they drop in altitude. If you start at normal flight levels of 10-12km you can glide up to 200km (or even more if you can use thermal updrafts). The main problem is that you have to get creative when it comes to slowing down as you probably can't use reverse thrust (and maybe even flaps if you are especially unlucky), if you don't have a rather long runway you might overshoot.

Btw, if we exclude intentional stalls (that won't be gliding) you can't realistically achieve a worse glide ratio than 4-5:1. NASA used heavily modified Gulfstream jets as a training vehicle for Space Shuttle pilots, and they had to extend the gears and flaps and use full reverse thrust to get a plane that was as bad at gliding as the Shuttle (it just doesn't have big enough wings to be a decent glider).

langwadt:

--- Quote from: jogri on August 11, 2020, 11:30:34 am ---
--- Quote from: sleemanj on August 10, 2020, 09:26:41 pm ---120km glide over the open ocean to the Azores (and they still had to lose excess altitude!).  A good example of how airliners are more like massive self launching sailplanes than we give them credit for.

--- End quote ---

Modern jets like the A320 or the 737 have glide ratios of 15-20 (sailplanes are in the range of 50-70:1), that means they can travel 15-20 miles for every mile they drop in altitude. If you start at normal flight levels of 10-12km you can glide up to 200km (or even more if you can use thermal updrafts). The main problem is that you have to get creative when it comes to slowing down as you probably can't use reverse thrust (and maybe even flaps if you are especially unlucky), if you don't have a rather long runway you might overshoot.

Btw, if we exclude intentional stalls (that won't be gliding) you can't realistically achieve a worse glide ratio than 4-5:1. NASA used heavily modified Gulfstream jets as a training vehicle for Space Shuttle pilots, and they had to extend the gears and flaps and use full reverse thrust to get a plane that was as bad at gliding as the Shuttle (it just doesn't have big enough wings to be a decent glider).

--- End quote ---

afaik thrust reversers are never a requirement for safe landing, it just saves on brakes and might help a bit if it is very wet
the A380 doesn't even thrust reversers on all it's engines

I think I've read some where that the glide ratio on a wingsuit is ~2 .5:1

ConKbot:

--- Quote from: langwadt on August 11, 2020, 12:49:12 pm ---
I think I've read some where that the glide ratio on a wingsuit is ~2 .5:1

--- End quote ---

Wouldn't be that surprising. Mike Patey filmed a stunt where a wingsuit flyer held the wingtip of his plane, requiring heaps of reverse thrust (negative angle on the variable pitch prop), so he could be in a step enough dive and not speed away from the skydiver.

https://youtu.be/Jdccr7qm5NA

So at least a couple hundred HP in reverse to begin to match their glide ratio.

jogri:

--- Quote from: langwadt on August 11, 2020, 12:49:12 pm ---afaik thrust reversers are never a requirement for safe landing, it just saves on brakes and might help a bit if it is very wet
the A380 doesn't even thrust reversers on all it's engines

I think I've read some where that the glide ratio on a wingsuit is ~2 .5:1

--- End quote ---

Yes, technically thrust reverser are optional on a dry runway and you can land without them, but you shouldn't do it... This is what it looks like when you try to stop a 747 with worn out brakes without thrust reversers:



The A380 doesn't have thrust reversers on its outer engines because those aren't over the asphalt of a normal airstrip and you would blow up a lot of debris from the ground/grass that then gets sucked into the engines.

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