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This "Sketch Book"
collection of handy tips appeared in the September 1949 issue of Air Trails
magazine. The monthly series ran for many years, as you can see from the big
list of other Sketch Book (aka Sketchbook) features at the bottom the the page.
One of the more technical tips has to do with locating the center of lateral
area (CLA) of a model. The author does not mention that it is important to make
sure the model profile cut from cardboard can rotate freely on the pin (or nail)
so that gravity will have it settle in the correct position. Otherwise, the
location of the weighted string relative to the model profile will not be
accurate. With the tip for remotely locating the engine needle valve, the
magazine editor seems to be a bit dubious about the scheme, and asks, "How about
it, experts - think it'll work?" Since then a number of glow fuel engines have
been made with essentially that scheme, so it must be feasible, although maybe
the venturi and fual/air intake system for the engine might have to be
specifically designed to accommodate it.
Sketch Book
Have you developed something new in construction, control, or flying that might
interest other modelers? Send a rough sketch - we'll redraw it and pay $2 for each
one accepted.
 • Boeing engineer Archie Chapel, Wichita,
Kan., has tips for strong gas model wing structure similar to full-scale aircraft
practice. "I" beam weighs 60% of solid spar.
• Precise longitudinal adjustment of hand-launched glider by means of wedge
positioned in angularly-cut fuselage boom is novel trick by Charles Francis, Hamburg,
N. Y.
 • For special installations, Larry Lundy,
Lockport, N. Y., proposes a remotely-located needle valve. He suggests use of Bantam
parts. How about it, experts - think it'll work?
 • Neat control line handle with quick
adjustment of sensitivity is idea of Ernest Iversen, Chicago, Ill. Steel retaining
wire held in position by spring tension of angled ends.
 • Bob Leisses, Beaver Dam, Wis., has
been using this sliding canopy on his realistic gassie. Hatch slides bock along
wire guides, giving access to battery inside the cockpit.
 • Few modelers can use 200-ft towline
to full advantage because of erratic flight in tow. Gregg Conlon, San Francisco,
Calif., adds 2nd tow hook, kite tail for stability.
  • You can't use the C.L.A. (center
of lateral area) as a design factor until you learn to locate this elusive point.
Lawrence Miller, Norfolk, Va., uses this simple method: cut scale profile of model
out of cardboard, including projected dihedral; punch hole near each end. Suspend
by pin through each hole, mark the perpendicular by string and weight. Intersection
of two perpendiculars is C.L.A. point. A third point, in wing, can be used for cheek.
Posted March 26, 2022
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