Maximum vertical acceleration for a jet plane while landing?

Question

For a typical commercial airline jet (such as a Boeing 747), what is the max vertical acceleration when landing?

Trying to do a Calculus project, can't seem to find this answer anywhere...

Answer 1

Do you mean descent rate? cause a plane is not really accelerating, it should have a more or less constant vertical speed. If you mean the vertical speed than it depends on the aircraft you are flying. The faster you are traveling, the higher the vertical speed. To maintain a normal approach path you have to multiply the speed in knots times 5 and add 50. That should give you approximately the vertical speed in feet per minute that an aircraft is descending on final. The aircraft will not hit the ground at that speed! Before touchdown the pilot will normally pull the nose up to flare the aircraft. This means we will descend more slowly than on final approach. The vertical speed on touchdown varies very much depending on how the flare was executed.

EDIT: Ok I get what you mean now. It varies from right over 1G's to approximately 1.6 G's, which is considered a very hard landing.

Answer 2

Not more then -200FPM for a nice smooth landing

Answer 3

depending on how well the aircraft was landed, it's typically in the range of 1.3 to 1.7g's.

Answer 4

When landing and the sink rate is constant there is no acceleration up or down.  

When the plane touches down, the sink rate goes from, say 200ft/min to 0ft/min in a few seconds, so there is acceleration usually measured in G's.  The smoother the landing, the lower the G's.   Hard landings that exceed the limits of the aircraft require a "Hard landing Inspection".  The more severe the landing, higher G's or higher sink rate require a more in depth inspection.

I've done them on a 747 but I don't remember the limits.  

MD80  http://209.85.173.104/search?q=cache:p5v...  "Hard landing limits: More than +2.0 g or sink rate in excess of 10 ft/s (600 ft/min)"

From what I've seen recorded and described, 2'g is a very hard landing.   Some people would get hurt in a landing that hard as well as the plane and 600ft/min would feel like a dive.

Edit

That chart is to show what is a typical landing and was used to come up with this http://www.boeing.com/commercial/aeromag...  For Boeing aircraft it's from 1.7-2.1 g's

BTW A landing will could never be less than 1G.  1 vertical G is the force of gravity, so a plane sitting on the runway in already at 1G.

Answer 5

Here is a link with some 737 landing measurements.

For the 737 a hard landing is considered to be at 1.1g.  So somewhere below that. Say 1 g?

edit:

someone seems to be confused between g-force and acceleration. Vertical acceleration is 0g at rest. Acceleration being the dv/dt. The question was what is the deceleration rate normalized by gravity, not the g-force one experiences.

I also found a better source on landing gear design. A typical transport has a deceleration rate on landing of 0.7-1.5g. See link below where the load factor N = (Force on the Shock)/mass/gravity = acceleration/gravity = vertical acceleration rate in g's. Add 1 for g-force.  

http://books.google.com/books?id=XMpdOeW...

Answer 6

Sorry, I can't be very specific, but I can give you the sources I used for a similar project.

According to Source 1, the horizontal deceleration for a passenger plane should not exceed 8 feet per second squared (1/4 "g").

Source 2 says that humans can withstand much higher horizontal g-forces than vertical g-forces without having side effects.

Also, the normal acceleration should be less than the limit.

Answer 7

If he's in a landing descent there would be no 'vertical' (upward) acceleration.