Great Circle routes

zoidberg said:
'Different ships, different longsplices.'


I seem to recall, if fraying memory still serves, that what we were chasing was best Specific Fuel Consumption or SFC. More miles per gallon....
It was also noticeably colder way up there, which the engines liked, with more 'Bernoullis per square yard' which the wings liked. Also, no rain or snow - most of the time.
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One hates to interrupt but from my seat we were chasing Specific Air Range = TAS/(SFC*Drag).
Optimal AOA at 1.32Vmd and best SFC hence trade speed for height to keep the engines in the optimum band.

"Eng out"
 
All this high altitude and oxygen, great circles and so on that professional aviators have to jump through hoops with. What gripped my sphincter was having to do my ATPL performance exam based on a VC10 at 30000’. A complete waste of time when there’s an H at the end of your licence. Fuel endurance has to be less than or equal to bladder endurance in the rotary field.
 
boomerangben said:
I think the general idea is that icing is mainly an issue below about 20000’ so the object is to get above that as quickly as possible. Moreover aircraft have de ice and anti ice kit as flying a lollipop is no fun.
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I could tell you a tale that would have you squirming in your seat about sitting behind a JP in a Can T4 who ran us into the top third of a humungeous CuNimb over the Orange Free State at FL350, which gave immediate total canopy ice whiteout, near-immediate both burners flameout, then being hit sequentially by Thor's Hammer up the jaxxie then down again, repeated - which broke every gyro instrument in the aircraft.

Boy hero had been warned, due to the howling/squealing on the radio-compass kit, and requested to climb up a bit to have a look. I knew about CuNimbs and airframe icing. He knew better.....

The lifting and control surfaces picked up tons of crinkly ice in so many seconds. The ASIs read nonsense. There was a 'departure from controlled flight' and then some. The pressure altimeters unsteadily wound down through thirty, then twenty-five, then twenty, then fifteen.... we were supposed to offer up a prayer to Martin-Baker at 14 and leave.... my straps were tight, visor down, gloves on, and taking up the First Pressure at ten when we were spat out the side into (brighter) sunlight.

Boy hero rolled wings level and had another couple of attempts, got one working, and levelled out - sort of. We limped home. The airframe was Cat 4 Unserviceable.

Fellah-me-lad left and immediately took up a post with South African Airways, operating 747s out of Jo'burg. Through the ITCZ. At night....


*One of the best-thumbed books on my bookshelves is 'Fate Is The Hunter'. Everyone but everyone who flies need wary airmanship.
 
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zoidberg said:
I could tell you a tale that would have you squirming in your seat about sitting behind a JP in a Can T4 who ran us into the top third of a humungeous CuNimb over the Orange Free State at FL350, which gave immediate total canopy ice whiteout, near-immediate both burners flameout, then being hit sequentially by Thor's Hammer up the jaxxie then down again, repeated - which broke every gyro instrument in the aircraft.

Boy hero had been warned, due to the howling/squealing on the radio-compass kit, and requested to climb up a bit to have a look. I knew about CuNimbs and airframe icing. He knew better.....

The lifting and control surfaces picked up tons of crinkly ice in so many seconds. The ASIs read nonsense. There was a 'departure from controlled flight' and then some. The pressure altimeters unsteadily wound down through thirty, then twenty-five, then twenty, then fifteen.... we were supposed to offer up a prayer to Martin-Baker at 14 and leave.... my straps were tight, visor down, gloves on, and taking up the First Pressure at ten when we were spat out the side into (brighter) sunlight.

Boy hero rolled wings level and had another couple of attempts, got one working, and levelled out - sort of. We limped home. The airframe was Cat 4 Unserviceable.

Fellah-me-lad left and immediately took up a post with South African Airways, operating 747s out of Jo'burg. Through the ITCZ. At night....


*One of the best-thumbed books on my bookshelves is 'Fate Is The Hunter'. Everyone but everyone who flies need wary airmanship.
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What on earth is he talking about? :unsure: :rolleyes: 🤣
 
zoidberg said:
I could tell you a tale that would have you squirming in your seat about sitting behind a JP in a Can T4 who ran us into the top third of a humungeous CuNimb over the Orange Free State at FL350, which gave immediate total canopy ice whiteout, near-immediate both burners flameout, then being hit sequentially by Thor's Hammer up the jaxxie then down again, repeated - which broke every gyro instrument in the aircraft.

Boy hero had been warned, due to the howling/squealing on the radio-compass kit, and requested to climb up a bit to have a look. I knew about CuNimbs and airframe icing. He knew better.....

The lifting and control surfaces picked up tons of crinkly ice in so many seconds. The ASIs read nonsense. There was a 'departure from controlled flight' and then some. The pressure altimeters unsteadily wound down through thirty, then twenty-five, then twenty, then fifteen.... we were supposed to offer up a prayer to Martin-Baker at 14 and leave.... my straps were tight, visor down, gloves on, and taking up the First Pressure at ten when we were spat out the side into (brighter) sunlight.

Boy hero rolled wings level and had another couple of attempts, got one working, and levelled out - sort of. We limped home. The airframe was Cat 4 Unserviceable.

Fellah-me-lad left and immediately took up a post with South African Airways, operating 747s out of Jo'burg. Through the ITCZ. At night....


*One of the best-thumbed books on my bookshelves is 'Fate Is The Hunter'. Everyone but everyone who flies need wary airmanship.
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Do bomb aimers ever say 'back a bit'??
 
Minerva said:
There are folk out there that genuinely think bill gates put 5g microchips into a vaccine so that he could track their whereabouts!

Never underestimate the levels of stupidity in some parts of the general public.
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Ah, but that is really, really true!! I have had a stiff neck ever since my first Covid jab 'cos it lodged there!!
And Elvis lives in my village too but he did change his name before he moved here.
 
On a pertinent note. Back in '82 I flew home from Oz via Japan. On the second leg, the plane flew from Japan to Anchorage, and whilst I don't know the exact route, we flew over the tundra then over polar icecap and down the coast of Greenland and down over Scotland. I was lucky enough to have a window seat; it was spectacular.
 
wonkywinch said:
The CAA rules on oxygen say "You and other members of the crew must use oxygen continuously whenever the cabin altitude exceeds 10,000 ft for more than 30 minutes or any time above 13,000 ft."

This means you can fly (in an unpressurused plane) at 13,000 for 30 mins then come back down to 10,000. As altitude is your friend in a single engine plane over the sea, whenever I flew from southern UK to La Rochelle or the Channel Islands, I used to climb up to 13,000 then within 30 mins come back down again. A typical trip to La Rochelle, this would work out just right allowing for the climb and descent. Trying to do even simple mental arithmetic gets noticeably much harder at that altitude.
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One of my skydiving friends, very bright, was on a big formation jump. After a slow, formatted climb and on the run in, 13 000 ft, he couldn't stand up. So he took out his knife and slashed the seat belt!
 
Chiara’s slave said:
I believe gravitational gradient would tear you apart. They are after all just one step short of a black hole.
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Exactly, though of course it would depend on how far you were from it. After all, the Sun may end up as a white Dwarf or Neutron star, so their mass is about the same, and the gravitation field of a body depends ONLY on its mass, not its density. Orbiting one at the distance of the Earth from the Sun wouldn't involve massive tides. But to be close enough to see a disc might well do so. At our distance, the likely cause of death would be irradiation by massive flares caused by material falling to the star's surface.

"Dragon's Egg" by Drake is a nice SF story about a neutron star, including a sort of plausible way to avoid the tidal issue! And, of course, Asimov wrote about the tidal issue in a short story; I forget the title.
 
AntarcticPilot said:
Exactly, though of course it would depend on how far you were from it. After all, the Sun may end up as a white Dwarf or Neutron star, so their mass is about the same, and the gravitation field of a body depends ONLY on its mass, not its density. Orbiting one at the distance of the Earth from the Sun wouldn't involve massive tides. But to be close enough to see a disc might well do so. At our distance, the likely cause of death would be irradiation by massive flares caused by material falling to the star's surface.

"Dragon's Egg" by Drake is a nice SF story about a neutron star, including a sort of plausible way to avoid the tidal issue! And, of course, Asimov wrote about the tidal issue in a short story; I forget the title.
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One of my very few successes in getting an answer from the first clue in Only Connect was when the first card read “falling into a black hole”, to which I guessed ‘spaghetti’. I may be exaggerating; this might have been my only success.
 
AntarcticPilot said:
Exactly, though of course it would depend on how far you were from it. After all, the Sun may end up as a white Dwarf or Neutron star, so their mass is about the same, and the gravitation field of a body depends ONLY on its mass, not its density. Orbiting one at the distance of the Earth from the Sun wouldn't involve massive tides. But to be close enough to see a disc might well do so. At our distance, the likely cause of death would be irradiation by massive flares caused by material falling to the star's surface.

"Dragon's Egg" by Drake is a nice SF story about a neutron star, including a sort of plausible way to avoid the tidal issue! And, of course, Asimov wrote about the tidal issue in a short story; I forget the title.
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White dwarf, not neutron star, the sun has insufficient mass to collapse that far. But yeah, any neutron star you can see as a disc, and you’re already dead, only a matter of what’s killed you first.!
 
boomerangben said:
I think the general idea is that icing is mainly an issue below about 20000’ so the object is to get above that as quickly as possible. Moreover aircraft have de ice and anti ice kit as flying a lollipop is no fun.
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Icing is temperature rather than altitude related although the two are linked by the adiabatic lapse rate. In commercial flying icing is considered (and we switch on the anti ice) at +10C and below in visible moisture (vis less than a mile on the ground).

Below -40C icing no longer an issue except consideration to supercooled rain, ie water below 0C still in liquid form, which is what got Air France 447.

Rough rule of thumb, take surface temp, knock off 10 degrees, divide by 2 so even in 30C, icing conditions may be experienced (in cloud) above 10,000 feet. The freezing level (0C) is c 5,000 above that.
International Standard Atmosphere - Wikipedia
 
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