This first report
intentionally contains the necessary documentation to justify the
the Jim Adams Cloudster plan for the SAM Speed 400 electric event.
After scaling the Baby Playboy plans and
modifying the front end, fortunately Ned Nevels pointed out that it was
against the Speed 400 rules to use the rubber version of the Baby Playboy
plan. So I decided to discontinue the Baby Playboy project for my Speed 400
I spent most of last week searching for
another model suitable for the Speed 400 event.
While going through my collection of
plans, I ran across a set of hand drawn "Cloudster" plans shown below. A
number of years ago, Dick Huang ran me off a copy of the one he had gotten
from Jim Adams, a long time experienced modeler and leader in the SAM
movement. Jim had apparently drew these plans up for the SAM 1/2A Texaco
event because the plans show an R/C version using a Cox .049 for power. Dick
had very carefully calculated the plan's wing area to be 352.16 sq. in. and
wing span as 51.70 inches.
Shown below is the title block on these plans. If the
1938 date is accurate, the Cloudster should be an Antique and it is gas
powered so it meets the SAM Speed 400 electric rules.
These Jim Adams plan was
compared with a set of original Cleveland Cloudster plans whose title block is
The Cleveland Cloudster plan illustrates both wing dihedral and polyhedral
as shown below. Since there is no date in the title block, I do not know for
sure if the Cloudster plan qualifies as an Antique or not, but it certainly
is an Old Timer, which is all I need for the Speed 400 event.
I compared the Cleveland plan with the Jim Adams plan and the two check out
OK, except for the nose section forward of the wing's leading edge. The
Cleveland plan shows an inverted Ohlsson 23 ignition engine for power. The
distance from the wing's leading edge to the rear face of the prop plane
measures 4-1/4" as shown below.
For comparison, the Jim Adams plan below shows an upright Cox .049 engine
for power. The front end has been modified and the firewall has been tilted
for down thrust in the Cox engine. However, the distance from the wing's
leading edge to the rear face of the prop plane is the same as the Cleveland
plan (4-1/4") as shown below. So the Jim Adams plan also has the same nose
moment as the original Cleveland plan. After consulting with Gene Wallock,
Dave Harding, Jack Hiner, and Jim O'Reilly several times, I have concluded
that the Jim Adams plan qualifies for the Speed 400 event.
It was thought that the Speed 400 rules contained an 8 oz/sq.ft. wing
loading requirement. However, during the Cloudster plan discussions, a
surprise discovery was made that there is no wing loading requirement in the
Speed 400 rules. As a result, I settled on a scaled down wing area of 300
sq. in. for the Cloudster. The scale factor applied to the plan is
SQRT(300/352.16) = 0.923. Yesterday I had the plans scale down for a wing
area of 300 sq. in. and I will build the Cloudster incorporating the
polyhedral wing configuration.
So after all of these discussions, calculations, and comparisons, last
evening I finally got started building something! :O< I laid up the
Cloudster's first fuselage side using the scaled down plans as shown below.
The longerons and forward vertical members are 3/16" square, however the aft
fuselage vertical members are reduced to 1/8" X 3/16" to save weigh. Notice
that I am building the fuselage with the down thrust built into the firewall
as per the Jim Adams plan......................Tandy