Thursday, March 13, 2008 - 21:42:55 ET

Calculating G-Forces in a Turn

A while back I posed the question "Does an airplane in 45° bank experience more G forces than a slower one?"

The quick answer: No. The G forces (or load factor) on the aircraft does not change based on the speed you are flying.

The equation to calculate load factor (n) is as follows:

Where Theta is the angle of bank.

Since the angle of bank determines the load factor and not speed, a faster aircraft at 45° will experience the same load factor of a slower aircraft at the same angle of bank.

The only thing that is different is the radius of the turn. A faster moving aircraft will have a larger turn radius at the same angle of bank than a slower aircraft.

In all instances we're talking about true air speed (TAS).

So lets use two aircraft. A Cessna 172, and a Piper Seminole. Both are excecuting a 45° bank turn. The 172 at 90KTAS and the Seminole at 130KTAS:

Cessna:

Seminole:

This is important information to know, especially if you are flying in canyons or other places with limited area to maneuver. If you need to turn 180° in the smallest amount of distance, its best to slow down before executing the turn (see comments).

Don't forget! Your stall speed increases as the angle of bank increases.

I was never good at math, so please correct me if iIm wrong. The formula states "velocity" and not speed. So I'm unsure if I can use KTAS or if I need to convert that into feet per second.

Oh and where did I get 11.29? See the bottom of this page.

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