October
24, 2007
Awaiting arrival of original factory drawings to get started, GLee UL version
was good for scaling figures but, not much else for this application. Plan is
to accurately input the originals into Rhino in order to "build" her
in cyberspace and get a 3d picture.
Have to look at Skybolt, Pitts, Hatz and, others to see what to do about wing
structures. Want to do all Al. skeleton for the wings If I can but, wood not
yet fully ruled out. Must remember to dig out my references next trip to
Appaloosa. Aerodrome forum was productive for additional reference material.
Received Vickers mini datafile, Lewis still pending.
October 26, 2007
Have noted that the Skybolt, Pitts, Hatz and particularly the 1 1/2
Strutter in the
November
3, 2007
Continued wait on delivery of factory drawings and reference library. Review of
factory originals for Pup and 1 1/2 Strutter in the meantime. Coming to
conclusion that these aircraft are all variations of same design. Could
extrapolate Baby from the others but, want to see float design /
struts on original.
Wing structure material choice issue not yet resolved. Favor wood for ease of
construction / authenticity issues but, Al. not ruled out for dimensional /
environmental issues. Suspect key may revolve around environmental issues.
Confident answer will reveal itself in time.
Note to self: Review Gougeon Brothers text regarding expected
dimensional changes for a given humidity in terms of % of change.
Addendum:
Have made today initial stab at target gross weight of 1,270 lbs. Basing this in comparison to original specifications in Datafile for the 130hp Clerget Baby, with a full military load weighing in at 1,742 lbs and the following calculations / assumptions.
Calculated stall speed of 130 hp Clerget Baby @ gross weight = 35 mph.
Desired stall speed of replica baby = 30 mph
Further
assumptions....
174.2 lbs = 10% (arbitrary) weight reduction from original gross for use of modern materials.
267
lbs = Reduction of
"Military Load."
November 6 , 2007
Have noted reference Nov 3rd entry, faulty reasoning on two accounts.
- Cannot assume weight reduction utilizing modern materials.
- Extrapolation of gross wt via desired Vsl likely not viable.
Basis for this new revelation on observation of two long established full scale
WWI replicas utilizing 4130 tube fuselages and wooden wing structures. One a
Nieuport 17 and the other a Fokker Dr.1. In both cases, significant gains in
empty weight over the original specifications have been realized in the
following percentages....
Model
Original empty weight
Replica empty weight Percent
gain
(Redfern) Nieuport 17 827 lbs
1,004
lbs
17 %
(Sand's) Fokker
Dr.1 895
lbs
1,150
lbs
22 %
Noted further is how above gains for the replicas are without "military
load."
Based on this empirical evidence I must adopt the original gross wt for the 130
hp Clerget Baby and calculate all structures for 1740 lbs.
November 9, 2007
After consulting design texts and concurrent with observations of Nov 6,
now fully versed in and keenly aware of the "design weight spiral."
Question now is not whether weight gain will be realized but, by how much? The
two existing published examples are suggestive of an average 20% but, are
too small of a sampling for accuracy. However, the following weight
savings over the 130hp Clerget original are more certain......
130hp Clerget dry weight 110
hp Rotec Radial
Weight Savings
381
lbs
224
lbs
157 lbs
Reduction of military
load
267 lbs
= 424 lbs
The necessity of CAD model comparison (with assigned densities of materials)
between original airframe structure and proposed 4130 design changes is
paramount to the decision regarding wing structures. The Svoboda Sopwith 1 1/2
Strutter and the Storo Bristol F2b are suggestive of success but, are private
designs without published results.
November 17, 2007
Arrival yesterday of long anticipated original Sopwith drawings. Have noted
that these include a mixture of the Schneider trophy winner as well as the later
versions.
Of particular interest are the float details which reveal obvious design
deficiencies as compared to modern standards. Wing structures and fuselage are
typical aside from an interesting departure from equidistant rib
spacing.
An interesting dilemma regarding the weight spiral is revealed in that the
original propeller diameter is a massive disk of 104". The Rotec R2800 has
a recommended prop diameter of 76" and the R3600 is 84". Along
with the 4130 tubing airframe and probable higher lift airfoil sections, the
ramifications are obvious. Will be in better position to deal with these issues
once the aircraft is built as per original specs in 3d. Due to personal
time constraints, I anticipate as much as a year to do this.
It is with the floats then that I will start my CAD work. Inputing the details
of the 1915 drawings will reveal areas for improvement in consultation with
texts and more modern float design plan-sets.
December 8, 2007
Preliminary
CAD work on main float confirms prior suspicions regarding
required internal structural design improvements. Original canvas
bulkheads are an obvious start along with rib structure. Modern
compartmentalization is assured. Of issue now is whether or not to maintain
external authenticity in favor of a new stepped bottom profile and propeller
spray considerations.
December 22, 2007
Continuing questions regarding floats and water operations in general. Slow
progress on CAD work. Original design used confusing and (no doubt) mass
production adverse, internal load transfer structures. Have joined Seaplane
Pilots Association (SPA) in effort to increase education. Ordered design text
referenced by Peter Bowers, (Seaplane Design, by William Nelson, McGraw Hill
Book Co., 1934 edition).
