Wing Inertia - what is it?
 

Model Aviation's latest issue on page 40 and following was an article that used the term "wing Inertia" as the opposite force from lift. I have never heard that term before, so can anyone help me understand that concept?

I haven't read that article but the way you wrote your part of the post in quotes doesn't make sense. The inertia of the wing is not directly related to the lift of the wing. And it's not accurate to say that inertia is the opposite of lift.

Both light and heavy wings will make the same lift if of the same size and same angle of attack. But the heavy wing has more "inertia" that resists changes in rolling. So it takes more control input to force a heavy wing into a given roll rate or to stop the rolling compared to a light wing. And a heavy wing will tend to not be as affected by turbulence than a lighter wing. By the same token though when a heavy wing IS disturbed it will require more rolling force to correct the disturbance.

I will try to post a pic

I would check the author of said article and avoid any of his advice. :)

The author appears to know his subject. The problem is that he has attempted to condense a number of college level aero engineering courses into a short magazine article. I fear the only people who will follow what he's saying are engineers who have already taken all the courses themselves.

I don't get that magazine so have not read the article. But the diagrams showing the wing's lift acting against the wing's inertia is rather odd. For static conditions everyone else labels those arrows as either "aircraft weight" or "aircraft mass" with the idea that gravity works on the mass to produce what we call "weight". So unless the article is talking about the effects of control inputs and how the wing's inertia due to its mass affects the rolling inputs I sort of wonder about the use of that term in what seems to be the context of the diagrams given the static case picture at the top of the stack. Perhaps if we could read the small print, which is totally unreadable in the picture, the use of the term in this situation might make sense.

I read that article also - had to reread it 2-3 times to figure out why he used the word Inertia. I believe he was incorrect. I believe he was talking about the weight of the wing, which makes more sense to me. Inertia is not measured in units of force, so it cannot act against Lift.

So reread the article, and just insert wing weight in place of wing inertia. I agree with OTRCMAN's conclusion, about the author having to condense many details into a simplified explanation. Using the term inertia confused things.

Added: I also presume this to be wing weight and not aircraft weight. Why? Because if one uses his diagram and want to use those numbers to calculate wing bending loads at the wing/fuselage intersection, wing weight would be opposing lift. I would typically leave that entire term (wing weight) out. It's probably a magnitude (or more) less than the lift, and will provide you a more conservative answer.

Thank you! I will re-read it and see if I can comprehend it now.

If I may butt in and confuse things ...

I believe the author is referring to the inertia that develops during vertical acceleration. It is additive to weight (when pushing upward and visa-versa). That is inertia and impacts the design as the author states.

Bedford

Typical cring-worthy MA News article by amateur "engineer". I wish this publication would vet these authors better.

Which is more often referred to as G load acting on the wing's or other object's mass. Again inertia isn't a great term to use for this. Inertia is more often used in association with an object's resistance to change in speed. Which would show up in terms of getting the plane to start into a fast rolling maneuver or to quickly stop the wing when the ailerons are neutralized. Or in the tendency for the nose and tail masses to resist a change in the speed of a pitching maneuver. "Speed" in this last sense being fully capable of being from "0" to some pitching rate or from some pitching rate (say a loop for example) and going back to "0" when returning to straight line flight.

Again I just can't see using the term "inertia" unless dealing with the momentary transitions related to such directional changes, Now if that is what the article is about then fine. But if it is not about this sort of transitional changes then it's a very odd use of the term.

Did not see the dates