Design > Engineering board
How many g's?
Matt Colan:
How many G's does someone put on a plane during a pattern? I was just watching a Red Bull Air Race and they go up to 12, but I figure a lot more (hey the plane's flying at 55mph, making a 10ft radius corner).
Anybody got an idea H^^
Alan Hahn:
Since this is the engineering forum, we need the formula for acceleration for circular motion,
a=v2/r,
v being the velocity in m/s (54 mph ~24m/s), and r=radius of circle in meters. A 10 foot radius corner is about 3 meters, so in this case the acceleration is 192 m/s2.
Since "g"=9.8 m/s2 (~10 m/s2), this means you are pulling about 19 g's in a 10 foot radius corner at 54 mph.
I will note that you can increase this by 1 g to 20 g's from level since at the first pull out you also have to fight gravity.
Paul Smith:
I agree with your 20 G estimate for model airplanes.
But based on avaiton physiology taught in the USAF and personal expience in the T-38, I doubt the 12 G's for a man-carrying airplane. 7 or 8 is more like it. Even with a G suit, 8 G's is a lot of G. Maybe a Red Bull can spike up to 12 instantly before the airspeed bleeds off, but it can't be pulling 12 more than a fraction of a second, if that.
Mark Scarborough:
Hving just finished watching two episodes of the Red Bull Air races on my DVR tonight, they dont pull that G load very often, and I think it is sustained for a second or at most two. Typically when I see that , its on the pullout vertical , sort of an immelman or a half loop with a roll back to upright.
They do pull 11 much more frequently however, and last year one of the pilots was DQ'ed because he pulled 13.2 Gs for an extended period.
Alan Hahn:
I thought the +12g rating on full scale aerobatic aircraft (like a Pitt's Special) was more to inspire confidence that the wings wouldn't fall off n1 than a rating that flying actually attained!
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