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Chat Area => General Discussion Area => Topic started by: MR MISTER on 22 December 2013, 22:05:53

Title: Get ready for a wet and windy one
Post by: MR MISTER on 22 December 2013, 22:05:53
Was that...


A) Me listening to the weather forecast?

B) Me warning the wife about what's to come later?
Title: Re: Get ready for a wet and windy one
Post by: 05omegav6 on 22 December 2013, 22:12:18
Have you had you evening bowl of Branflakes with warm milk then ::)
Title: Re: Get ready for a wet and windy one
Post by: MR MISTER on 22 December 2013, 22:12:46
Have you had you evening bowl of Branflakes with warm milk then ::)
Horlicks.
Title: Re: Get ready for a wet and windy one
Post by: 05omegav6 on 22 December 2013, 22:31:57
Have you had you evening bowl of Branflakes with warm milk then ::)
Horlicks.
Same to you :o
Title: Re: Get ready for a wet and windy one
Post by: Nickbat on 22 December 2013, 22:37:06
Was that...


A) Me listening to the weather forecast?

B) Me warning the wife about what's to come later?

Incredibly strong jet stream. I saw a tip about this on a weather forum.

A Boeing 747 normally has a max cruising speed up to Mach 0.88 (583kts). I just noticed a 747-800 (Polar Air) flying east at 636kt (731mph)!!!  :o :o :o

http://www.flightradar24.com/PAC956 (http://www.flightradar24.com/PAC956)

 
Title: Re: Get ready for a wet and windy one
Post by: tunnie on 22 December 2013, 22:38:58
Never knew TB drove 747's  ;D  ::)  ::) ::)
Title: Re: Get ready for a wet and windy one
Post by: Nickbat on 22 December 2013, 22:48:38
Strongest jet stream this forecaster has seen:

http://www.bbc.co.uk/weather/features/25485532 (http://www.bbc.co.uk/weather/features/25485532)  :o
Title: Re: Get ready for a wet and windy one
Post by: Rods2 on 22 December 2013, 22:49:10
It all those Christmas sprouts washed down with good strong stout, that will cause it.  ;) :P :o :o
Title: Re: Get ready for a wet and windy one
Post by: Rods2 on 22 December 2013, 22:50:37
Strongest jet stream this forecaster has seen:

http://www.bbc.co.uk/weather/features/25485532 (http://www.bbc.co.uk/weather/features/25485532)  :o

Not so good if you are flying in the opposite direction.  :o :o :o :o
Title: Re: Get ready for a wet and windy one
Post by: Nickbat on 22 December 2013, 22:59:44
Was that...


A) Me listening to the weather forecast?

B) Me warning the wife about what's to come later?

Incredibly strong jet stream. I saw a tip about this on a weather forum.

A Boeing 747 normally has a max cruising speed up to Mach 0.88 (583kts). I just noticed a 747-800 (Polar Air) flying east at 636kt (731mph)!!!  :o :o :o

http://www.flightradar24.com/PAC956 (http://www.flightradar24.com/PAC956)

 

I suppose that raises an interesting engineering question. I presume that an aircraft can exceed its max speed if it pushed by a tail wind since the air resistance is so much lower that it does not stress the airframe. Thus, in theory at least, a 747 could break the sound barrier if it has a strong enough tail wind?  ???
Title: Re: Get ready for a wet and windy one
Post by: Entwood on 22 December 2013, 23:01:22
Jet stream is "relatively" narrow, especially the strongest, core element ... so by going 100 miles north or south it makes a big difference to winds ...

NAT tracks - North Atlantic tracks - are computor generated  to optimise costs/time for all crossings.

jetstream predictions ..

http://www.netweather.tv/index.cgi?action=jetstream;sess=
Title: Re: Get ready for a wet and windy one
Post by: Nickbat on 22 December 2013, 23:03:32
Was that...


A) Me listening to the weather forecast?

B) Me warning the wife about what's to come later?

Incredibly strong jet stream. I saw a tip about this on a weather forum.

A Boeing 747 normally has a max cruising speed up to Mach 0.88 (583kts). I just noticed a 747-800 (Polar Air) flying east at 636kt (731mph)!!!  :o :o :o

http://www.flightradar24.com/PAC956 (http://www.flightradar24.com/PAC956)

 

That flight is now showing 660kts (759mph!!) :o
Title: Re: Get ready for a wet and windy one
Post by: 05omegav6 on 22 December 2013, 23:04:22
If you think Monday/Tuesday is going to be rough...

Check out Friday early morning here...

 http://magicseaweed.com/North-Atlantic-Surf-Chart/2/  (http://magicseaweed.com/North-Atlantic-Surf-Chart/2/)

As it comes round again :o
Title: Re: Get ready for a wet and windy one
Post by: Entwood on 22 December 2013, 23:06:43
Was that...


A) Me listening to the weather forecast?

B) Me warning the wife about what's to come later?

Incredibly strong jet stream. I saw a tip about this on a weather forum.

A Boeing 747 normally has a max cruising speed up to Mach 0.88 (583kts). I just noticed a 747-800 (Polar Air) flying east at 636kt (731mph)!!!  :o :o :o

http://www.flightradar24.com/PAC956 (http://www.flightradar24.com/PAC956)

 

I suppose that raises an interesting engineering question. I presume that an aircraft can exceed its max speed if it pushed by a tail wind since the air resistance is so much lower that it does not stress the airframe. Thus, in theory at least, a 747 could break the sound barrier if it has a strong enough tail wind?  ???

nope .. as the speed of sound is also affected by the speed of air movement .. exceeding the speed of sound means exceeding the RELATIVE speed of sound in your locale .. or the "air speed" .. the mach ratio remains the same regardless of windspeed,   so mach .65 in still air is 430 knots ground speed .. in 100 knot headwind its 330 knots ground speed, in a 100 knot tailwind its 530 knots ground speed ... the "airspeed" or mach no remains constant ...at 430 knots / .65
Title: Re: Get ready for a wet and windy one
Post by: 05omegav6 on 22 December 2013, 23:08:38
Was that...


A) Me listening to the weather forecast?

B) Me warning the wife about what's to come later?

Incredibly strong jet stream. I saw a tip about this on a weather forum.

A Boeing 747 normally has a max cruising speed up to Mach 0.88 (583kts). I just noticed a 747-800 (Polar Air) flying east at 636kt (731mph)!!!  :o :o :o

http://www.flightradar24.com/PAC956 (http://www.flightradar24.com/PAC956)

 

I suppose that raises an interesting engineering question. I presume that an aircraft can exceed its max speed if it pushed by a tail wind since the air resistance is so much lower that it does not stress the airframe. Thus, in theory at least, a 747 could break the sound barrier if it has a strong enough tail wind?  ???
Speed over ground is very different to airspeed, if a 747 went super sonic it would probably have bits fall off.
Also they're the wrong shape for it... a Boeing 727 is/was the fastest subsonic commercial aircraft...
Title: Re: Get ready for a wet and windy one
Post by: Nickbat on 22 December 2013, 23:08:53
Was that...


A) Me listening to the weather forecast?

B) Me warning the wife about what's to come later?

Incredibly strong jet stream. I saw a tip about this on a weather forum.

A Boeing 747 normally has a max cruising speed up to Mach 0.88 (583kts). I just noticed a 747-800 (Polar Air) flying east at 636kt (731mph)!!!  :o :o :o

http://www.flightradar24.com/PAC956 (http://www.flightradar24.com/PAC956)

 

I suppose that raises an interesting engineering question. I presume that an aircraft can exceed its max speed if it pushed by a tail wind since the air resistance is so much lower that it does not stress the airframe. Thus, in theory at least, a 747 could break the sound barrier if it has a strong enough tail wind?  ???

nope .. as the speed of sound is also affected by the speed of air movement .. exceeding the speed of sound means exceeding the RELATIVE speed of sound in your locale .. or the "air speed" .. the mach ratio remains the same regardless of windspeed,   so mach .65 in still air is 430 knots ground speed .. in 100 knot headwind its 330 knots ground speed, in a 100 knot tailwind its 530 knots ground speed ... the "airspeed" or mach no remains constant ...at 430 knots / .65

Thanks for the explanation. :y
Title: Re: Get ready for a wet and windy one
Post by: Rods2 on 23 December 2013, 00:30:19
Was that...


A) Me listening to the weather forecast?

B) Me warning the wife about what's to come later?

Incredibly strong jet stream. I saw a tip about this on a weather forum.

A Boeing 747 normally has a max cruising speed up to Mach 0.88 (583kts). I just noticed a 747-800 (Polar Air) flying east at 636kt (731mph)!!!  :o :o :o

http://www.flightradar24.com/PAC956 (http://www.flightradar24.com/PAC956)

 

I suppose that raises an interesting engineering question. I presume that an aircraft can exceed its max speed if it pushed by a tail wind since the air resistance is so much lower that it does not stress the airframe. Thus, in theory at least, a 747 could break the sound barrier if it has a strong enough tail wind?  ???

nope .. as the speed of sound is also affected by the speed of air movement .. exceeding the speed of sound means exceeding the RELATIVE speed of sound in your locale .. or the "air speed" .. the mach ratio remains the same regardless of windspeed,   so mach .65 in still air is 430 knots ground speed .. in 100 knot headwind its 330 knots ground speed, in a 100 knot tailwind its 530 knots ground speed ... the "airspeed" or mach no remains constant ...at 430 knots / .65

Thanks for the explanation. :y

Mach speed also varies with air temperature, pressure and humidity, with temperature variation making the biggest difference. This means that the speed of Mach one varies. The reason it is used is that the airflow effects over an object will be the same for any particular Mach number. At 30,000 feet it is about 0.89 of that at sea level.

Ground speed and indicated air speed are very different where indicated airspeed is a relative airflow speed measured with a pitot tube. Ground speed is not only dependent on wind speed but also aircraft attitude as it will decrease when you are climbing or diving.