@Bye
Thrust and momentum are completely different quantities, with different units/dimensions.Sorry Dave but you're wrong here.
Dave is right and you are wrong I'm afraid.
Thrust (like any force) is a
rate of change of momentum not momentum. Different units and different dimensions.
We have 2 aircraft
plane A weighs 300 Tonnes and plane B weighs 200 Tonnes.
Both are identical and have the same wing with the same Lift drag ratio of 17 similar to a 747.
Both aircraft are cruising straight and level at 400 Km/h.
Plane A at 300 tonnes lift has a drag of 300 / 17 which equals 17.65 units of drag.
Plane B at 200 tonnes lift has a drag of 200 / 17 which equals 11.76 units of drag.
Wrong again. The 300 tonne aircraft will have a lift coefficient 1.5 times greater than the 200 tonne if they are flying at the same speed. They cannot have the same drag coefficient or the same lift/drag ratio so the rest of the argument falls by the wayside - even without perpetuating the thrust = momentum error.
And just for the record, the 'heavy' aircraft in the picture I posted earlier was 1.3 times the weight of the 'light' one