What Hossfly is describing is an increditably quick and easy method to balance the vast majority of our model airplanes. Its so simple, its so quick and it works so good that its totally ignored in this computer fed society of helpless people. You don,t need a computer, you don,t need the plans, you don,t need to call some supplier and you don,t need count on some heresay about where to balance some model. What you do need to do is decide for yourself where you want to balance the airplane and thats the easy part.

Its called midspan averaging. Is it super accurate: No its not and it certainly does not have to be.

OK first for the midspan averaging part (piece of cake) Pick a point that is half way out between the wingtip and the fuselage. At this point measure the distance (a school ruler does just fine here) from the front edge of the wing and rear edge of the wing. Thats it, that is the Average chord (regardless of the wings leading and/or trailing edge tapers). The engineer types like to call this the Mean Aerodynamic Chord, MAC.


Now for the part were we the pilot/builder have to make a decision, what a concept And for that we don,t need a computer all we need is just a few old fashioned guide lines that never change whether or not its a gas/glow/electric or diesel airplane.

A few old fashioned guide lines expressed as a percentage back from the leading edge of that average chord we figured out above:

The vast majority of our trainers, sport airplanes and warbirds fly best at: 25% Mac and this is a perfect and safe starting place.

For fellows wanting to do the prop hanging stuff then 30 to 34% is appropriate but keep in mind its not for beginners and frequently lots of expo is used. Also the airplanes don,t fly very well in higher speed flight.

For leading edge tapered flying wings around 20% is a safe figure.

For a straght chord flying wing around 12 to 15% is the ticket to cool flights.

For controlline airplanes around 15% is a good starting place.


OK now we have made a decision and lets call it 25%, We just take that average chord we figured out with the tape measure or ruler and divide by four, That gives us the 25% place back from the leading edge half way out there between the fuse and wingtip. The last step is to just project that point inward to the fuselage (you can almost do that just by eyeballing along spar lines etc.) and this is the actual spot you want the airplane to balance level (not nose down for mother and country) when supported there on each side of the fuselage.

Took me forever to write this and it takes only a two or three minutes to actually do anywhere without this crutch called the computer.

Now following "A few old fashioned guidelines" will keep you out of trouble and will be agine "A good starting point" to experiment on your own and thats what this hobby/sport/passion is all about.

MJ Yes your airplane is being flown with the CG too far aft for you. The reflexing of the ailerons up or down does have effects that can improve various segments of flight but usually at a cost of some other end of the flight envelope.

Hoss sorry for repeating your post in kind more or less but just hoping to help get the point across.

John