This is certainly true for ion engines because they burn for such a long time, but chemical rockets burn so quickly that the change in gravitational acceleration during a burn is very small. Their burns can usually be modeled as instantaneous impulses with little error.
It is a significant factor during initial launch, because about 1 g of acceleration is lost just keeping the rocket from falling back to Earth. A rocket that produces just 1 g will hover without climbing and burn all its propellant without going anywhere. The higher the acceleration, the lower these losses during the initial climb and acceleration to orbital velocity.
Once you're in orbit, this isn't so...typical maneuvers don't use any thrust to directly counter gravity, and the Oberth effect actually makes it preferable to make maneuvers that change the specific energy of the orbit deeper in the gravity well.
Try to keep to topic, i.e.
So, who wants to win 1 million Euro? As I am offering the €1M award, you have to listen to me and ... be polite. Do not post nonsens posts that I am uneducated, blah, blah. Only uneducated idiots do that, so please avoid it.
One hurdle seems to be how to slow down, brake, the space ship on arrival Moon to get into orbit around Moon as described in previous posts. The space ship is pretty heavy, 43 000 kg, and has just one big rocket engine that can apply a 97 400 N force on it by clicking a switch. The fuel consumption seems to be 30 kg/s. You are in 3-D. To apply the strong force, 97 400 N, it must be applied in the right direction all the time and the direction changes all the time as you turn into orbit. In this case you also go backwards as you are braking - slowing down - and you are pressed into your seat while braking ... looking aft. It is quite complicated and I wonder how the NASA pilots did it.
Apollo 11 apparently managed to slow down from 2400 to 1500 m/s speed by braking at full blast for 6 minutes wasting 10 000 kg fuel in 1969 with the pilots looking in the wrong direction and to win 1 million Euro you have to repeat it.
Navigation at sea is also complicated -
http://heiwaco.tripod.com/news8.htm . Do not ever blame the Master if anything gets wrong.
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