Joint Strike Fighter Plan B

[DanTheMan]

If you wanna talk weapons then an ex-RAF bombhead is the way to go. Now where can we find one of those.....


One of the best stories I ever heard was about spy planes just after the cold war. There is a famous photo of this hanging up at most squadrons in the UK:

Just after Red Flag the yanks sent over one of their sneaky beaky spy planes and took a photo directly over Parliament. They sent the picture over to basically say that our defences were inept and that we were at risk. Followed by them laughing. This was their super spy plane that had been torn a new one by a Raptor crew the previous Red Flag so they were trying to make a point. But we sent them a photo back of their plane taking the photo of Parliament. Seems we had a Canberra a few miles above their plane and had been circling above it for hours.

True or not it makes no difference when you're trying to wind the yanks up in the dessert.

[hyperD]

As a non-pilot, why is the pressure relevant? Altimeter mechanism? In which case, is that why flight levels are not reported less than 3000 - atmospheric variation makes the unreliability more dangerous?

Don't think I could explain better than Wiki:

Altitude has most easily been measured using a pressure altimeter, which is essentially a calibrated barometer — it measures air pressure, which decreases with increasing altitude.

To display altitude above sea level, a pilot must recalibrate the altimeter according to the local air pressure from time to time, to take into account natural variation of pressure over time and in different regions. If this isn't done, different aircraft may be flying at different heights even though their altimeters show the same altitude. More critically, different aircraft may be flying at the same height even though their altimeters show different heights.

Clearly this is a safety issue.

Flight levels solve this problem by defining altitudes based on a standard pressure of 1013.2 mbar. All aircraft operating on flight levels calibrate to this same standard setting regardless of the actual sea level pressure.

Flight levels are then assigned a number, which is this nominal altitude ("pressure altitude") in feet, divided by 100. Therefore an apparent altitude of 32,000 feet is referred to as flight level 320. Note that an aircraft flying at flight level 320 will usually be at some other actual height above mean sea level than 32,000 feet, but since all other aircraft set their altimeters to a standard pressure, no collision risk arises.

To avoid collisions between two planes, their real altitudes are not important, but only the difference between them. This difference solely depends on the air pressure at both planes, and does not require knowledge of the local air pressure on the ground.


There you go...

When setting QNH (local altimeter pressure) for lower altitudes, there an old pilots expression that says: "From High to Low, beware below" i.e. if you are flying from a high pressure to a low pressure area (normally straight into a wx front or lowered ceiling situation) and you don't reset the altimeter, you will be flying lower than you should and could get into a situation of controlled flight into terrain.

[hyperD]

Apologies, for the mis-quote must read pprune more carefully. To be clear IIRC it was a flypast at 80 feet, climbing from 60.

In the same vein does anyone know of the field attacked by Buccaneers on exercise which required the Buccanneers to make their final approach inverted to avoid negative-G over a hill on the way into the field.

And as for the JSF thread and some mockery of USAF coding try http://www.pprune.org/forums/showthread.php?t=255422

No problems! Good thread btw.

[DaveB]

you will be flying lower than you should and could get into a situation of controlled flight into terrain.

Otherwise known as crashing....

[wendigo100]

Thanks Hyper.