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The ballasted gliders resist deceleration better than
the unballasted ones. Golf balls are another example. If we shoot a golf ball straight up and a ping pong ball straight up at the same velocity, the golf ball will go much higher because it resists deceleration better (has more momentum). Given two objects of equal drag, the heavier one will go higher, if we ignore the idea of the 'wing' and the need to translate horizontal to vertical momentum. If we include the concept of the wing, at some weight difference between the gliders and at some selected initial airspeed, the additional angle-of-attack required by the ballasted glider pull-up causes enough additional drag to negate the benefit of momentum and the unballasted glider climbs higher. The two easy special cases to consider a 1) unballasted glider with weight = 0 and 2) initial airspeed = ballasted glider's stall speed. If 1 and 2 are true, both gliders attain the same height gain of 0. If 1 only is true, the ballasted glider climbs higher. If 2 only is true, the unballasted glider climbs higher. For other values of weights, initial airspeeds, and drag/lift, 'it depends...' The easy math shown here demonstrates that all three cases ,, and = are possible. |
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