Hi gang, here I go again,
I am going to risk the possibility of another personal attack on my
building know-how by asking for help in a problem I have with the KR plans.
In checking the plans, Drawing #2 for the KR2, [this sheet is included ,
as you know ] in plans for the KR2S I checked the angle of incidence by running
a line from the bottom of the two spars and extending it till it intersected
with the extended chord line of the rib. Measuring 48" from the intersection
the distance between the thrust line, and the angle of incidence of the wing
could be determined in inches.
As most of you agree, the plus 3.5 degrees incidence is excessive. had
intended to reduce this regardless of the airfoil I used. However, I wanted to
see how much I would have to shim the lower longeron at Stations G & H.
To my surprise my measurements indicate the angle of incidence, if you
follow the plans exactly, give a 7 degree angle, not 3.5. I arrived at this
conclusion by multiplying the 48" chord by pi. Finding the circumference, I
divided by 360 to get the inch equivilent to a degree. Multiplying this by
3.5 I would get the angular difference between the chord line of the rib and
the thrust line of the fuselage in inches.
Let me digress for a moment, I KNOW that ALL of you are perfectly
familiar with finding the relationship between degrees and inches. I just felt
that letting all of YOU know that I do, too. It might finesse aspersions re.
my I.Q.
I believe, with all the KR's that have been, or are being built, someone
checked this out. The only mention in the manual or the plans is to use the
top longerons as reference. But the attach points on the lower longerons are
parallel at Stations E and H at 20" to the top longerons.
Could it be possible that a "strictly plans built" KR2 or 2S could be
flying with a 7 degree angle of inc.
My question is, as Bill O'Reilly would say, where have I gone wrong Is
my geometry that bad, should I abandon all hope of building a KR2S and as has
been suggested, start learning to be a GOOD pastry chef?
Happy New Year to everyone, Bob Tallini
