What current airliner has the best glide ratio?

[silverfoxcc]

Reading another forum, and it said thec747 had a glide ratio of 17-1. is this average or are there better designs now?

[Panamax]

Boeing 787 = 20:1

[Brother D]

Top level gliders have a staggering 75:1 ratio - that's insane! I wonder how the 787 would do without engines wouldn't be surprised if that was up in the 30 to 40 range.

[ShredderXLE]

For the completely uneducated (and cant watch youtube on phone) are these ratios quoted horizontal distance covered : vertical height lost?

[48k]

ShredderXLE said:

For the completely uneducated (and cant watch youtube on phone) are these ratios quoted horizontal distance covered : vertical height lost?

Yes, with the aircraft in "best glide" configuration, so for example in the case of an airliner it would be gear up, no flap, trimmed for best glide speed whatever that is for the particular aircraft.

[ShredderXLE]

Wow! That seems terrible. I dont know why but I always assumed that most air liners would be much better than that. Through work I spend a bit of time drawing up DDA access ramps at 1:20 so can easily picture what that angle looks like. I'd just assumed it was in the 1:100s. Oops.

[Panamax]

ShredderXLE said:

Wow! That seems terrible. I don't know why but I always assumed that most air liners would be much better than that.

Well, stick a couple of huge, modern, high bypass engines on a glider and see how things work out.

You can't escape weight (mass) vs gravity but everything else is to play for.

Here's a crazy idea. Maybe airliners with engine failure should have explosive bolts to blow those heavy engines off....

[Brother D]

ShredderXLE said:

Wow! That seems terrible. I dont know why but I always assumed that most air liners would be much better than that. Through work I spend a bit of time drawing up DDA access ramps at 1:20 so can easily picture what that angle looks like. I'd just assumed it was in the 1:100s. Oops.

One in 20 is still quite something. That's a shallow pitch angle of less than 3 degrees - Those giant disks the size of a 737 fuselage on each wing must produce an insane amount of drag.

[48k]

ShredderXLE said:

Wow! That seems terrible. I dont know why but I always assumed that most air liners would be much better than that. Through work I spend a bit of time drawing up DDA access ramps at 1:20 so can easily picture what that angle looks like. I'd just assumed it was in the 1:100s. Oops.

Looking at it another way and this is an albeit contrived example in perfect conditions, no wind etc, - with a 17:1 glide ratio, if the aircraft starts gliding at 30,000 feet, then that's 95 miles range / 24 minutes flying time (at 200kts) before it reaches the surface.

[djc206]

I’ve always been given a rough guide of 1000ft every 3nm (~18000ft). I’ve never actually though of it that way though and it’s quite impressive

[Gunso]

The maximum operating altitude of a 787 is 43,000'.

43,000 times the glide ratio of 20:1 is 860,000'.

860,000 divided by 5280 (the number of feet in a statute mile) is about 163 miles.

[s2000db]

Remember this?

https://simpleflying.com/air-transat-flight-236-hi...

[2xChevrons]

48k said:

Looking at it another way and this is an albeit contrived example in perfect conditions, no wind etc, - with a 17:1 glide ratio, if the aircraft starts gliding at 30,000 feet, then that's 95 miles range / 24 minutes flying time (at 200kts) before it reaches the surface.

The famous Gimli Glider was 17 minutes from running out of fuel at 41,000ft to its landing/well controlled crash. It covered 80 miles across the ground.