Weight, Balance, and Moment CFI Work

A1FlyBoy

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Hey,

As a CFI I'm sure many of you, at different times, seek different ways to freshen up your approach at teaching a particular subject. This keeps material fresh, interesting, and provides new ways of explaining a topic.

I'm curious how many of you explain weight & balance with a PARTICULAR emphasis on WHAT IS MOMENT? to students from Private to Commercial applicants.

At our flight school I've had some commercial applicants who could certainly do a proper weight and balance, but when we got in to really talking about what IS MOMENT, WHY do we care, etc they couldn't really explain it.

What are some of your explainations of Moment..what, why, how, etc?
 

Timebuilder

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When an example of moment is required, I use leverage as an example. The fulcrum is the CG (or new CG, if load is being changed) and the length of the lever is the arm distance.

I have drawn a see-saw on the white board with a very large child on one end, and a small child on the other, and discussed what effect a change in the placement of the fulcrum, or "hinge point" has on the ability of the small child to raise the heavy child.

Once this concept is grasped, make up some weights for the children and some distances from the fulcrum, and viola! -weight multiplied by arm equals moment. In short, moment is an easy way to quantify the effective values of the children in the example, or the weights and their placement in the aircraft.
 

sstearns2

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......

A moment is a force multiplied by a distance. Moment is a word that hasn't entered the language much outside of physics and engineering. I'd equate it to the word torque. Torque and moment have essentially the same meaning, but are used in differnent contexts. Most people are much more familar with the word torque.

Scott
 

FSIGRAD

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A good way to demonstrate an increase in moment is to have your student pick up their flight bag with one hand (a normal student bag filled with the average crap weighs about 30 lbs.)

First have them hold it close to thier chest.... not so bad could stand like that all day...next have them extend their arm straight out in front of them and hold the bag. That takes a lot more work and they can probably do it only for a minute or two.

Why? the moment of the bag just increased (distance from fulcrum) Works the same way in an airplane.
 

avbug

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If you want to show them why they should care, then show them a picture of a smoking hole in the ground made by an airplane that took off with an improper CG or weight. Do they need any more reason than that?
 
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