Aerodynamics: plane weight vs wing & tail lifts

[Stoney]

Moment is actually a physics term I believe, but it basically refers to the force imparted on an object from a certain direction (vector) that results from the force times the arm.  The arm being the distance between where the force is applied and where it is imparted.

A simple example if I got my terminology incorrect above is a box wrench.  Your hand turns the wrench (force).  The distance between your hand and the bolt you're turning is the arm, and the moment would be the resulting force you impart on the bolt. 

(Physics majors be gentle... )

[Motherland]

Thanks stoney

[Casca]

Moment is actually a physics term I believe, but it basically refers to the force imparted on an object from a certain direction (vector) that results from the force times the arm.  The arm being the distance between where the force is applied and where it is imparted.

A simple example if I got my terminology incorrect above is a box wrench.  Your hand turns the wrench (force).  The distance between your hand and the bolt you're turning is the arm, and the moment would be the resulting force you impart on the bolt. 

(Physics majors be gentle... )

That is exactly right but a little over complicated.  Moment is just another word for torque.

[AKHog]

Physics related question... I've seen it a couple times now... what is moment?

Fixed.

Look up moment arm. Basically, its a component in the equation to calculate the force of a lever.

[AKHog]

Opps I didn't see the second page before I replied.

[Cthulhu]

That is exactly right but a little over complicated.  Moment is just another word for torque.

Actually in typical engineering usage, moment & torque are used in different contexts. We'd never refer to how much moment an engine produces, or how much the peak torque would be in the middle of a bridge span. Moments (at a point) are considered to be produced by force(s) some distance (the moment "arm") from that point. So a moment is generally associated with bending, hence the term bending moment. Torque is usually associated with a pure twisting "force" (although in purist's terms, the word "force" is incorrect). A good example of torque would be that transmitted by a drive shaft.

Oh, and ignore the guy from Carolina. I think he just makes stuff up.

[Casca]

I understand perfectly what you are saying but for what he is trying to do the plain meaning of each is interchangeable and expressed in the same units.

[Cthulhu]

I understand perfectly what you are saying but for what he is trying to do the plain meaning of each is interchangeable and expressed in the same units.

I wasn't my goal to correct you, but to simply standardize the terminology for future communication. It should also help the OP to better understand any technical references he comes across in his search for info.

[Old Sport]

Don't know if the following NACA report will help, but it does provide calculations and some direct data about tail surface forces.

Flight measurements of aerodynamic loads on the horizontal tail surface of a fighter-type airplane

John B. Garvin
naca-tn-1483
Nov 1947

A comprehensive investigation was conducted to determine the loads applied to the horizontal tail surface of a fighter-type airplane in maneuvering flight. Differential -pressure-distribution methods were employed to obtain the values of load. Loads were measured at equivalent airspeeds ranging from 125 to 380 miles per hour and at accelerations up to 6g.

http://aerade.cranfield.ac.uk/ara/dl.php?filename=1947/naca-tn-1483.pdf

Enjoy!

Note:
Actually this particular report was mentioned several years ago here in a long discussion about how planes should react after their horizontal stabs and elevators are shot away i.e. nose up or nose down.
 
 

[Ex-jazz]

  Old sport

The page 9 give an answer. I assume the main wing airfoil moment is also effecting at 'Xt' I.E. Neutral Point.