Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds
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Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds
#2Ground speed
Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds
#3Note to readers, land speed not equal to air speed. As the article discusses it doesn't break the sound barrier.
That said, the news here is that the jet stream is carrying more energy than it has in the past (air mass is moving faster, kinetic energy content is 1/2mv^2). I read a paper a long time ago which talked about the impact of thermal 'tubes' where denser cold air travelling at speed would "punch holes" in high pressure systems leading to more complex weather patterns. Sadly I cannot find it! The question I think about when reading this is the impact on the duration and temperature swings of the winter months in the north east of the continent. In particular, atmosphere so cold as to support hurricane formation over land. Most famously exploited in a fairly mundane movie "the day after tomorrow" but the modelling works if the temperatures meet certain conditions.
I don't know if winter "super storms" are possible due to other moderating influences but if they are, having the jet stream behave in a new way is a prerequisite (feeding very cold air into the system).
Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds
#4Ground speed
Isn’t that the one that truely matters some you want to go from A to B?
Genuinely curious I know nothing about aviation.
Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds
#5Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds
#6This is probably a stupid question, but how is "ground speed" measured?
Is it how quickly the airplane moves past a fixed point at it's altitude, or along the earth's surface? I.e. the plane is effectively moving along the surface of a sphere, but if the plane is 30,000 ft up, then the radius of the plane's sphere is 30,000 ft greater than the radius of the "ground" so traveling at the same angular velocity will require a higher speed the higher you go.
If I'm thinking about this right, across their respective "planes," the airplane will be moving faster than it's shadow. So maybe a better way to ask this is: is ground speed the speed of the plane, or the speed of its shadow?
Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds
#7Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds
#8Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds
#9This is probably a stupid question, but how is "ground speed" measured? Is it how quickly the airplane moves past a fixed point at it's altitude, or along the earth's surface? I.e. the plane is effectively moving along the surface of a sphere, but if the plane is 30,000 ft up, then the radius of the plane's sphere is 30,000 ft greater than the radius of the "ground" so traveling at the same angular velocity will requ…
Hm, I think the difference is marginal because of the large radius of the Earth, at least for planes.
Re: Boeing 787 Reaches 801 MPH as a Jet Stream Packs Record-Breaking Speeds
#10Ground speed
Isn’t that the one that truely matters some you want to go from A to B? Genuinely curious I know nothing about aviation.
I suspect that a 787 traveling at 801 MPH airspeed might suffer some damage to the control surfaces. 787s aren't designed to break the sound barrier.
And I would argue that not damaging the plane matters more than how long it takes to get there.