ORIGINAL: MTK
ORIGINAL: BillS
I hope to end up with incidence designed for the Kougar, Zero, Zero, Zero.
How I have been adjusting the incidence.
I use a short level and a Robert Incidence Meter and a bunch of shims under the wheels. First I disconnect the aileron linkage and clamp both to centered. I set the airplane wheels on the shims and level the horizontal stabilizer with the shims until both sides of the stabilizer are level and the same. I then tape the shims together as a set for each wheel. Then I check the incidence on each wing and make notes. I remove the wing from the airplane and shim the saddle with a short 1/2 " shim at the appropriate location. I put the wing back on and check the incidence on both sides again. The process is repeated until the incidence is very close. When close I slide soft balsa with glue in the gaps between saddle to wing. The soft balsa is sanded and the saddle gap is checked periodically.
I also have a set of micrometers and vernier calipers. Usually I feel funny measuring wood with a micrometer. Also it is easy to calculate angles from measurements which I usually do with props.
vicman is correct I fly mostly upright but believe that 4 degrees of prop down looked stupid. It also triggered obsessive compulsive tendencies.
Bill
Hi BillS,
4 degrees downthrust is likely okay for certain models such as high wing, high lift undercambered foil. Keeps that type of model from zooming.
In the case of the Kougar tho, it is a symetrically foiled sport model intended for a wider flight envelope. Itwould be better if set-up with zero on stab and engine and just a triffle +incidence on wing. Everything will improve. Locating the CG at 25%-30% of the MAC would beanother adjustment I'd make.....
One thing I'd suggest regarding using shims under the soft wheels, you might consider not doing it that way. Reason is that any additional weight (adding the I Meter) will squish the soft foam and throw your measurements off. It would be better if you shimmed the fuse directly. The I meter will produce adequate results as long as you are certain the needle doesn't stick and model doesn't move when youinstall the meter.
If you have a large enough, known flat surface to work with, and IF (big IF) you are not satisfied with the results from an I meter, let me suggest using a non contact meter
<span style="color: #ff6600">such as a Height Gauge</span>. It requires that you locate the airfoil centers precisely and marking with a fine point pencil or marker. A Height Gauge requires a flat reference surface to work precisely. Properly used, it can produce and reproduce any fractional angular adjustment one needs. I developed this technique eons agoto set up my precision birds.
Regarding angles, here's a simple way to remember how much slope results in 1 degree.....just remember the digits 1 and 4.A 1/4" difference in 14" of span is equal to 1 degree. In other words, for a 14" prop, the right tip as measured from the fin post should be 1/4" shorter than the left, for 1 degree of right thrust. Few things we do come out exactly at 14" of course, but as a rule of thumbit should help you gauge accordingly
But again, in your application, the I meter is probably adequate