Contrails

[1DC]

I hope this isn't too obvious to everyone else but I'm so curious about it I've joined the forum to get an answer. I live near HUY and about an hour ago a 4 engined aircraft passed over, very high and emitting strong contrails. The contrails on one side of the aircraft stayed as a continuous line but on the other (port side, i think) broke up into very clear, equidistant, circles, at a point about half a mile behind the aircraft. Why would this be??

regards...

[BOAC]

1DC - the only thing I can think of at the moment is that for some reason the engines (port and starboard) were running at different exhaust temperatures, either from different thrust settings or from different engine installations. Different engine mixes are not uncommon, but different thrust settings would be unusual!

Over to the experts?

[1DC]

BOAC, many thanks for your response. I'm amazed how many people read these threads!!

regards,..