The problem is that moving the weight out to the front edge 20 1/8" you have issues with the cowl vibration and coming loose. As mentioned, unless you have a really heavy duty cowl, or special mounting, that is not the best place to mount the weight. So that leaves you back at less than mid cowl - motor mount area.
If we could just make the props out of lead or heavy steel and the motor could handle it then our problems would be easy to fix...................
K
Originally Posted by
radiisteve
High Guys Just seeing this post on balancing and have a couple ideas to share. I've been balancing Medical Linear Accelerators and Airplanes for 25/45 years and with some simple math we can perhaps add "less weight for the same effect."
Your message said ( I did a rough balance and I need another 6 lbs weight in the nose to balance her out.),
· So if you have the engine, muffler, prop and a nut?? HH Nut?? and it takes 6 lbs to balance at mid cowl (setting weight on it),
· Then going out to the inner cowl diameter (estimated 20 1/8" from CG scaling the plans pdf as compared to approx 16 3/8" to mid cowl) you'd only need 4.88lbs to balance.
· The Moment Arm Formula is simply weight X distance = Moment Arm force (or effect if you will = MAE).
· If you add a "Really Big Prop Nut" from Harry Higley (roughly 8oz. compared to the STD Big 4oz prop nut), you can reduce the front cowl weight to approx 4.27 Lbs and save more weight overall.
· W x D = MAE (weight x Distance = Moment Arm Effect called MAE)
· Having a MAE number calculated, you can always divide that MAE by a different desired placement (measure distance from CG), and simply divide the previous calculated MAE by the desired location distance to get a corrected weight required for the same balancing effect.
· End effect, 6lbs @ 16 3/8” (mid cowl) = 98.25MAE.
· So when we review the front edge cowl placement (20 1/8” from CG), and divide 98.25MAE by 20 1/8” we get a revised weight of 4.88lb required to balance.
· Add the effect of the “Really Big Harry Higley Prop Nut”, and you reduce the weight needed to approximately 4 1/4 lbs required to balance the plane. That’s almost two pounds less (1.75 lbs. or 29.17%).
Good luck with your Corsair!