G Forces & Descent Rates

[Aidan Monaghan]

- At what descent rate (FPS) are negative G forces encountered?

- What formula calculates G forces of an aircraft transitioning from a descent angle X and descent rate Y, to level flight?

(EG: Descent Angle: 10 Deg. to 0 Deg.; Descent Rate: 10K FPS to 0 FPS)

Appreciated.

[MechEngr]

G excursions are from transitions between rates, not from the rates themselves. If you are descending at 10k fps there are far worse problems, like incandescent heating from compression effects.

10k FPM = 166 FPS. If the change is uniformly over 166/32.2 seconds (5.2 seconds), that will add a 1 G to the existing 1G. To keep to adding only 0.1 G is a 52 second pullout.

[Aidan Monaghan]

Appreciated.

[Luc Lion]

Even if you descend vertically, as long as you descend at a constant vertical speed, you experience a positive 1G.
If you want to experience negative G, you need to add a downwards vertical acceleration that exceeds the gravity acceleration, so that the sum of the two is negative.