Ref Chapter 5 Ans: sum of 4 forces is always zero, provided that it is a steady flight!   Steady flight? -i.e unaccelerated status! Based on Newton’s 3rd law (every action or force there is an equal, but opposite, reactionor force.) However, amount (magnitude) of 4 forces not exactly same! Weight cancel out by Lift … Continue reading 4 forces in steady flight?