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Mrs Mav

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Hoop, it was less of a publicity stunt than it seemed / I had feared. I also heard RB interviewed on the radio the evening before. The gist seems to be that he accepts that he has been turned down on the chance to operate them, but believes that they should be returned to the place where they were built (can't remember the name of the airfield) and a couple of them kept flying for special occasions, rather than BAs proposal of giving them to museums where they will lose flying status.

 

Rachael, there was a headline on straight after the Concorde programme (well done C5 - show a prog about how ace concorde is, then immediately report an emergency landing!) about an 'engine problem' forcing an JFK-LHR flight to land (safely) at Cardiff, if this is the same thing? Looks like BA say it was a fuel shortage - it has returned safely to LHR now.

See here and here

 

Steve, it was a BA one. All the french ones have been broken up *thumbdown* ☹️

If those pesky frogs hadn't left a heouge chunk of metal on the runway... which would have downed _any_ plane that hit it. There's an element of "unlucky" there ☹️

 

I thought the concorde doc was pretty good *thumbup* but then I don't dislike Mr Branson.

I wanna go... *thumbup* shame I never will *thumbdown*

 

mOOOm

 

www.megabird.co.uk

 

Edited by - moomin on 19 Sep 2003 14:54:24

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Sounds like compressor surge which would have resulted in a very load bang and maybe a flame out of the engine in question. I guess if you are flying at twice the speed of sound and monkeying around with the air intakes to slow the velocity of induction gasses, things will go bang from time to time ... they should have used a ramjet hybrid or like the SR71 did 😬

 

S713UMY

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Pat, compressor surge is a kind of engine stall ..... if too much gas is going out the back end and not enough gas is going in the front end then there will be a point when gas tries to flow through the engine in the wrong direction.... or the vacuum caused puts the light out *eek* ...

 

Traditional gas turbine surge (that is compensated for with valves) happens at start up when too much gas is heading into the front and not enough gas is coming out of the back .... Constipation if you will *tongue*

 

S713UMY

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😬 you asked for this:

 

Compressor surge is the utmost compressor stall phase. Due to a massive blading stall (high angle of attack) effective flow area reduces to a point where the compressor (or some of its stages) is unable to “push” air from a lower to a higher pressure level. At that point air begins to flow naturally from higher to lower pressure (flow reverses).

 

That is a “relief” to blades and they become efficient again (compressor is still rotating due to inertia although turbine is not providing power). Thus compressor recovers pushing air “upstream”, turbine starts to provide power (if there is no flame out), but stall may soon reach again the flow turn point. So the whole thing repeats and that is the surge.

 

Banging sound is due to alternating aerodynamic load exerted on blades. They are really clanging in their slots. Sometimes smoke may appear at intake if reverse flow lasts a little bit longer. Bear in mind that all these changes are a matter of fraction of a second.

 

Have forgotten to mention that during stall phase Turbine Entering Temperature (TET) is rising, not only because of airflow reduction but also due to fuel flow increase. Fuel system built-in-logic is to keep power turbine rpm constant. Since airflow is reduced in stalling phase PT rpm tends to drop. Sensing PT rpm reduction without a throttle movement fuel system interprets it as a load increase and reacts by metering more fuel to the combustion chamber.

 

That complicates the whole thing even more since the fuel system tends to increase amount of fuel in the surge phase too (if throttle lever is not retracted). All of that results in so rich mixture (airflow reduced drastically, fuel flow to large for it) that it can’t burn any more (believe it or not fuel extinguishes the flame or in other words extinguishes itself)

 

 

😬

 

S713UMY

1.8K Viper Blue and Black

 

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