3 ms·

That's the same if a jet engine losses power

p_l 4y ago
Nope. Look at the tiny wings, and at what speed it still depended on vertical thrust. It's going to have horrible glide ratio, which means unpowered landings might be, well, not a thing, which leaves you only with emergency full-plane parachute as an option. Pretty much all jet engine planes can do unpowered landings in glide, though admittedly some have pretty high speeds involved - but then they operate by default only on airports that have facilities for such speeds.
- oliveshell 4y ago
  See this famous example, where a jet airliner ran out of fuel in flight and glided to a successful landing: https://en.wikipedia.org/wiki/Gimli_Glider https://en.wikipedia.org/wiki/Gimli_Glider
  - kayodelycaon 4y ago
    Also Air Transat Flight 236. https://en.m.wikipedia.org/wiki/Air_Transat_Flight_236 https://en.m.wikipedia.org/wiki/Air_Transat_Flight_236
sokoloff 4y ago
If a [civilian] jet aircraft loses an engine, it's still a strong favorite to end that flight upright, intact, and on a runway. There are a couple dozen jet engine failures per year; the overwhelming majority end up in a safe conclusion. https://www.cbsnews.com/news/jet-engine-failures-rare-usually-not-fatal/ https://www.cbsnews.com/news/jet-engine-failures-rare-usuall...
CoastalCoder 4y ago
The movie Sully [0] opened my eyes to the amazing glide ratio of a commercial passenger plane like the A320. (I'm assuming that the movie was pretty accurate in that regard.) [0] https://en.wikipedia.org/wiki/Sully_(film) https://en.wikipedia.org/wiki/Sully_(film)
- nradov 4y ago
  Yes, the movie was accurate in that regard.
t0mas88 4y ago
Passenger jets have very good glide ratios. A 747 gliding with no power (all four engines somehow broken) from 10,000ft will get even further than a small Cessna 172 doing the same. This is counter intuitive to even most pilots, but it's how efficient the wing design on a passenger jet is. Their lift to drag ratio is better than small planes.
- fullstackchris 4y ago
  Is this achievable by the size of the craft itself? Or the fact that these bigger planes have 1000s of engineers behind them optimizing every possible factor to squeak out the best possible lift to drag ratio?
  - t0mas88 4y ago
    It's the overal effort that goes into the design, combined with a different design goal. Airliners are specifically optimised for low drag because it saves fuel. A Cessna 172 is a design from the 1960s that wasn't much optimised after that, and the design goal was stability and benign flying not the lowest possible drag. Later similarly sized small aircraft like the DA40 and SR20 are better at low drag because they're computer designed and fuel cost became more of a thing in modern times. For airliners the retractable gear saves tons of drag, but they also have things like winglets, and lots of smaller things like optimisation on the wing-root (airliners have smooth transitions here, trainers are sort of just square) that all reduce drag. An airliner is also much less friendly to handle in a stall condition, while a trainer almost recovers on it's own. And similar for yaw stability, if you get the rudder a bit wrong in a trainer nothing much happens, while an airliner will typically start to oscillate. Both of these are solved on the airliner by electronics, a stick shaker or pusher to avoid the stall and a yaw damper to enhance stability. The Cessna 172 doesn't have any electronics involved in flying, only for navigation and those are optional.

p_l 4y ago

Nope. Look at the tiny wings, and at what speed it still depended on vertical thrust. It's going to have horrible glide ratio, which means unpowered landings might be, well, not a thing, which leaves you only with emergency full-plane parachute as an option. Pretty much all jet engine planes can do unpowered landings in glide, though admittedly some have pretty high speeds involved - but then they operate by default only on airports that have facilities for such speeds.

oliveshell 4y ago
See this famous example, where a jet airliner ran out of fuel in flight and glided to a successful landing: https://en.wikipedia.org/wiki/Gimli_Glider https://en.wikipedia.org/wiki/Gimli_Glider
- kayodelycaon 4y ago
  Also Air Transat Flight 236. https://en.m.wikipedia.org/wiki/Air_Transat_Flight_236 https://en.m.wikipedia.org/wiki/Air_Transat_Flight_236

sokoloff 4y ago

If a [civilian] jet aircraft loses an engine, it's still a strong favorite to end that flight upright, intact, and on a runway. There are a couple dozen jet engine failures per year; the overwhelming majority end up in a safe conclusion. https://www.cbsnews.com/news/jet-engine-failures-rare-usually-not-fatal/ https://www.cbsnews.com/news/jet-engine-failures-rare-usuall...

CoastalCoder 4y ago

The movie Sully [0] opened my eyes to the amazing glide ratio of a commercial passenger plane like the A320. (I'm assuming that the movie was pretty accurate in that regard.) [0] https://en.wikipedia.org/wiki/Sully_(film) https://en.wikipedia.org/wiki/Sully_(film)

nradov 4y ago
Yes, the movie was accurate in that regard.

t0mas88 4y ago

Passenger jets have very good glide ratios. A 747 gliding with no power (all four engines somehow broken) from 10,000ft will get even further than a small Cessna 172 doing the same. This is counter intuitive to even most pilots, but it's how efficient the wing design on a passenger jet is. Their lift to drag ratio is better than small planes.

fullstackchris 4y ago
Is this achievable by the size of the craft itself? Or the fact that these bigger planes have 1000s of engineers behind them optimizing every possible factor to squeak out the best possible lift to drag ratio?
- t0mas88 4y ago
  It's the overal effort that goes into the design, combined with a different design goal. Airliners are specifically optimised for low drag because it saves fuel. A Cessna 172 is a design from the 1960s that wasn't much optimised after that, and the design goal was stability and benign flying not the lowest possible drag. Later similarly sized small aircraft like the DA40 and SR20 are better at low drag because they're computer designed and fuel cost became more of a thing in modern times. For airliners the retractable gear saves tons of drag, but they also have things like winglets, and lots of smaller things like optimisation on the wing-root (airliners have smooth transitions here, trainers are sort of just square) that all reduce drag. An airliner is also much less friendly to handle in a stall condition, while a trainer almost recovers on it's own. And similar for yaw stability, if you get the rudder a bit wrong in a trainer nothing much happens, while an airliner will typically start to oscillate. Both of these are solved on the airliner by electronics, a stick shaker or pusher to avoid the stall and a yaw damper to enhance stability. The Cessna 172 doesn't have any electronics involved in flying, only for navigation and those are optional.