If I were to take a profile plane and turn the wing around so the leading edge points to the tail then put the elevator on the other side of the stab and fly the plane bakwards. Would I want balance point to be the same place on the airfoil or more nose heavy?

Then down elevator would make the nose go up? It would work opposite right?

MM

The CG is going to be different. In the traditional layout, the tail is providing downforce at neutral for level flight. In a canard that is reversed--it is lifting. So the CG is going to move forward. And since the canard is creating upward lift in level flight, it has to make more lift to pitch the plane up, so the canard TE has to go down.

Quote from: Motorman on September 27, 2026, 07:36:22 PMIf I were to take a profile plane and turn the wing around so the leading edge points to the tail then put the elevator on the other side of the stab and fly the plane bakwards. Would I want balance point to be the same place on the airfoil or more nose heavy?

Then down elevator would make the nose go up? It would work opposite right?

 WAY further forward, like maybe a few inches ahead of the LE of the wing. Yes, down elevator would make it go "up".

    Brett

To make an aircraft stable and controllable the CG needs to be a bit in front of the aircraft Mean Aerodynamic Center. If you are a math guy then it a fairly simple summing of the area moments. Otherwise you can find some online calculators to do it for you. I found one here: 

https://www.rcplanes.online/cg_canard.htm

A wing's center of lift is at mean aerodynamic chord. For a perfectly straight Wing that's 25% back from the leading edge. So when you turn the wing around and put it in the same place, you significantly shorten the distance between the wing and the stab MAC.

That's one thing.

Then, there's the whole thing about neutral point which has been touched on.

I suggest that you grab some scrap balsa or some sheet foam or something, and make a little chuck glider.  Play with your planform, and your center of gravity.  When you get a glider that is nice and stable, remove the dihedral, scale it up to your intended size, and you should at least have something that will survive the first flight.

The "neutral point" , center of lift are colloquialism synonyms for the aircraft MAC. The conventional static margin of the aircraft is the distance in percentage in front of the MAC. The typical rule of thumb numbers are from 5% to 15% in front of the aMAC. This relationship holds true for most configurations. The process is to determine the location of the MAC by summing the area moments of all of the surfaces, then placing the CG as required. I've done this for many different configurations including canards,flying wings and joined wing aircraft. The latter were some very interesting airplanes and were well before their time when were tinkering with them.

I used the word "neutral" to denote level, unaccelerated and stable flight. The state in which all forces and moments are in balance. That is the starting point. I'm sorry I wasn't clearer, and no, I did not mean MAC.

Quote from: Dave Hull on September 29, 2026, 10:49:43 PMI used the word "neutral" to denote level, unaccelerated and stable flight. The state in which all forces and moments are in balance. That is the starting point. I'm sorry I wasn't clearer, and no, I did not mean MAC.

It's a non issue. Generally that's known as trim condition. The reality is the terms are used interchangeably. Stable is the property where the vehicle tend to return to it's trim condition. I'm just a total geekchild.

    Go to Outerzone and search out some canard designs, and see what some of those use for a balance point as a guide. James A. Wilson was a guy who lived here in the St. Louis area who had several designs published in the magazines over the years, including two 1/2A canard designs, The Corrigan, a 1/2A stunt model, and the Curtiss XP-55 experimental fighter. Jim was an interesting but quiet guy who loved diesels and when flying at Buder Park would go out, no matter what the conditions, and put up long flights just really wringing out the model he was flying with endless figure eights, loops and such down wind. I should have gotten some of my diesels out and learned how to run them from him. Jim Thomerson was another who was very good with diesels and lived near by and I should have taken advantage of his help also!! Wilson's XP-55 looks interesting and wood certainly get some second looks at the flying field!
  Type at you later,
   Dan McEntee

I think that my canard (in my avatar) is not the type under discussion here but for what it is worth; on the same design my balance point is 1" forward from where it was without the canard.  It wasn't stated if the canard was powered from the front or rear.  That matters since the airflow over the wing will be at a different speed.  That affects the strength of the CL and as a result the desired CG.

Ken

Advertise Here