ORIGINAL: Silver Flyer
I coiuld have gone out more with the engine but then the cowling would not have fit.
Adding dead weight is never desirable, but it is always better than flying a model that is balanced off the “magic point”. A few additional ounces will make the model flight a little faster, while an improper balanced model will never reach its peak performance. Using bigger batteries is a way to make the extra weight useful.
ORIGINAL: Silver Flyer
I have built a few models and have always put a swivel in the bottom of the fuse exactly where recommended and hung it from a ceiling hook, upside down, thus being able to balance in all directions before the plane was finished and covered. Always worked out well and never had to re balance. This is an ARF and only has ultrakote on the bottom so that couldn't be done this time.
May be you could try the ingenuous CG machine described in this link:
Vanessa CG machine:
http://home.mindspring.com/~the-plum...%20Machine.htm
If interested, you could read more about CG and balancing and trimming a model here:
Animation describing the theory behind the CG location:
http://www.geistware.com/rcmodeling/...rorgravity.htm
http://www.hebertcompetitiondesigns....ngulation.html
http://findarticles.com/p/articles/m...g=content;col1
http://www.flyrc.com/articles/03-16-...airplane.shtml
http://fatlion.com/sailplanes/divetesting.html
http://www.charlesriverrc.org/articl...GMarkDrela.htm
http://www.hebertcompetitiondesigns....ngulation.html
http://www.seniorpattern.com/pdf/BalancingAct.pdf
http://www.geistware.com/rcmodeling/...calc/index.htm
A model that is at balance at any CG machine, is supported at its CG.
A model that is flying, is supported by the air at the NP (neutral point) or CP (center of pressure).
For stable flight, there should be a distance between the CG and the NP, and the NP (point of support during flight) must be behind the CG (unique point around which the model rotates).
This distance is called stability margin.
Big stability margin: High pitch and yaw stability – low maneuverability (Like an arrow).
Small stability margin: Low pitch and yaw stability – high maneuverability.
If the CG is forced to relocate just behind the NP, the model becomes as instable as an arrow flying with the feathers at front.
Hence, there is a safe margin for CG located way ahead (a nose heavy model will fly poorly), but the margin is smaller and dangerous for CG located to far back (a tail heavy model will fly once).
Hence, the “magic point” or best location of the CG, as measured in a CG machine, is a matter of pilot’s preference and skills.
The designer will experiment with the model and will establish a range of CG location that is suitable for most of the pilots and most of the models built exactly as his drawings specify.
This should be taken as a first approach to proper balance.
The only way to find the “magic point” for YOUR model and for YOUR preferred compromise stability–maneuverability, is by experimenting and trimming.