Building Lasers

[RC Steve Sterling]

How do you find the center of the leading and trailing edges to those
accuracies??

I've been using the height gauge method on my pretty flat table, but I know
I can't register the center of the edges (especially leading) very
accurately.

  -----Original Message-----
  From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On
Behalf Of Rcmaster199 at aol.com
  Sent: Sunday, October 24, 2004 12:32 PM
  To: discussion at nsrca.org
  Subject: Re: Building Lasers


  Ken, pattern models need that kind of accuracy, and more, there's no doubt
about that. Bob has probably found that the lazer's accuracy of 0.1 degrees
is adequate for flying. If wings were off compared to one another by 1/32"
(0.1 deg), I believe that you would be able to see a difference in roll. But
if overall incidence (bothe panels compared to stab) was off by 1/32", you
would probably trim and keep on flying.

  The Robart incidence meter is okay as a broad reference device, but high
accuracy is not obtainable by this meter. It isn't made precisely enough for
our purposes; the variation in the plastic components is the killer. The
concept is not a bad one however; the blocks would need to be machined
precisely from block aluminum.

  Also, consider that any scribe mark you could place anywhere on a model as
the refernce mark to measure from, is at least about 10 thou thick. So the
best you could do in reality is to measure accuracy to within 10 thou or so,
based on your scribe marks' thickness, no matter the meter you use.

  For this reason, I prefer a simple height gauge with a carbide scribe
pointer. The scriber edge is approximately 1/2 thou thick so I can dissect
the 10 thou thick reference marks I placed on my wings, stabs or fuselage.
Then I am completely at the mercy of my  building surface. I use plate glass
for set-up and check it often for trueness when I am building. Believe it or
not even plate glass with take a set, so I rotate the surface periodically

  regards

  MattK



  Honestly Bob,

    I don't believe even the most precise fliers could tell if their wing
was off that little bit, or that most incedence meters can read it that
close.
    Unless you are doing your building off a surface plate, your chances of
getting your fuse's thrust line "perfectly" level, so as to make your
incedence's "that" close, are very slim indeed.  They will only be as close
as the accuracy of your incedence meter.
    I would like to have the manufacturer and part number of the incedence
meter that is that good, I just don't think my Robart is that close.

    Ken
      ----- Original Message -----
      From: Bob Pastorello
      To: discussion at nsrca.org
      Sent: Sunday, October 24, 2004 8:35 AM
      Subject: Re: Building Lasers


      .1 degree is also just a shade over 1/32" difference EACH at the
leading and trailing edges.  Understand that we need those kind of
accuracies for best, but I believe most folks do NOT resolve incidence to
1/32"....but I understand the need to state precisely.

      Bob Pastorello
      rcaerobob at cox.net
      www.rcaerobats.net


        ----- Original Message -----
        From: Karl G. Mueller
        To: discussion at nsrca.org
        Sent: Saturday, October 23, 2004 10:06 PM
        Subject: Re: Building Lasers


        Bob,

        A tolerance of .1degrees is not very close to set the incidence.
        Over a wing root of 20" it works out to be .035 inch. This is the
max.
        positive incidence I use on the wing when setting up a pattern plane
        with the stab being set to zero.  A  .1 degree tolerance could give
me
        a setting between 0 and .070 positive when setting up a wing with
        a 20" root.

        Karl G. Mueller
        kgamueller at rogers.com


          ----- Original Message -----
          From: Bob Pastorello
          To: discussion at nsrca.org
          Sent: Saturday, October 23, 2004 9:23 PM
          Subject: Re: Building Lasers


          The purpose of the ones I have is not to check incidence, but to
verify alignment "square", and "parallel"...currently, a lot of folks use
different methods, some height gauges, some fixtures.  When building a
plane, I have always struggled with getting the stab square to the fin, and
then the wing parallel to the stab...and these differences sure do make a
difference in how a bird trims out.

          Incidence is checked with our electronic digital levels, at .1
degree accuracy :-)

          Bob Pastorello
          rcaerobob at cox.net
          www.rcaerobats.net
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