hi guys,
Was out over St Louis the other day in the 777, looking out of doors 4 admiring the gorgeous sunset against our contrail when a collegue made an interesting statement,
"its weird to see the contrails so close but shows you how fast we're going."
Now that got me thinking, is the speed of the exhaust gasses a true reflection of our cruising speed?
Now one of newtons law's states that for each action there's an equal and opposite reaction which suggests that yes, the exhaust gasses travel at the same speed it is pushing us along at.
However i then thought thrust has to overcome drag which can vary due to aircraft attitude so more thrust would be required to maintain a certain speed and so exhaust gas speed would faster.
I'm now confused!
Any ideas?
kempus
