Originally Posted by
FlexibleResponse
An interesting analogy for those of us who have dropped bombs (and it would include other loads such as water bombers and helo external loads)…
Imagine a Lancaster bomber of a nominal weight of 45,000 lbs carrying a Tallboy bomb of 12,000 lbs for an AUW of 57,000 lbs .
The bomber is flying and trimmed in straight and level in (unaccelerated) flight at 18,000 feet and at an airspeed of 150 KIAS.
To do so, the power is set at say, 85% power and the wing AOA is generating lift force of 57,000 lbs to equal the total weight in level flight.
The crew then release the bomb over their target without changing any of the control positions or power setting. (Let’s ignore any trim changes due to changes in CG or airflow effects).
On releasing the bomb, the aircraft now weighs only 45,000 lbs…but crew maintains the power, speed and pitch attitude which are still set for a lift force of 57,000 lbs.
Will the aircraft:
A. Continue to fly straight and level at 150 KIAS;
B. Immediately descend with the bomb release;
C. Immediately climb as the lift force of 57,000 lbs far exceeds the new a/c weight of 45,000 lbs (increase in g); or
D. Enter a victory roll?
Now try the same bomb release in accelerated flight pulling up or recovering from a dive with increasing AOA and ask the same question re g force change.
Originally Posted by
Uplinker
The Lancaster bomber will climb after bomb release, but the forces in the wing structure will be less than they were when they were carrying the bomb.
With the bomb on board the wings are 'pushing up' with a force of 57,000lbs. After the bomb is released, the wings are still pushing up with a force of 57,000lbs, but the weight they are carrying is now 12,000lbs less, so the forces in the wing structure must be less - even though the aircraft climbs, and even though the aircrew will feel positive g.
i.e. The wings do not suddenly push up more at the point of bomb release - they are 'pushing up' the same as they were.
Agree with that.
If the pilots keep AOA constant the lift produced will remain at 57K so the aircraft will start pitching up and climbing. The pilots will feel positive G, but the wing load will remain steady (eventually the increasing pitch will lead to a decrease in speed).
If the pilots kept the altitude constant the lower pitch would lead to an increase in speed. The pilots will feel no G load, but the wings attachments will initially experience a reduction in load. (eventually the speed would stabilize at a higher point)
If the pilots keep the pitch constant it would be somewhere in-between the previous two scenarios.