Types of Model Aeroplanes
With a view to illustrating some of the models described in this book
complete, some drawings are given of the more successful designs which
have come into prominence during the past eight years. Fig. 11 shows
the Ridley Monoplane, which secured several well-merited rewards in
open competition, and is an excellent machine for distance. Birch
should be used for the longerons, preferably of channelled section.
The main plane is of piano wire, covered with proofed silk, and the
elevator is entirely of extremely thin veneer. Bentwood screws are used
fairly short in diameter and of long pitch. The machine is capable
of flying a quarter of a mile. The Fairey type of model aeroplane
typified in Fig. 12 is a most successful type, and has achieved much
in open competition. It has what is known as a floating tail, with no
leading stabilising surface, but a small vertical fin is used. This
is a practice the waiter is not personally in favour of, as through
such a long lever the slightest wind will cause great instability. If
a vane or fin must be used, it should be placed as far to the rear of
the machine as possible, preferably just behind, or in front of the
propellers for pusher machines, and the extreme end of the tail for the
tractor type.
The swept-back wing tips should have a negative angle of about
two degrees, and the tail should be quite flat in relation to the
horizontal.
[Illustration: Fig. 13.—Clarke Type Monoplane]
[Illustration: Fig. 12.—The Fairey Monoplane]
[Illustration: Fig. 11.—The Ridley Monoplane]
It has been stated that this machine is a highly successful one; it
is also exceedingly intricate in adjustment, and requires very calm
weather indeed to secure successful flights. It has also been flown
with great success by Mr. Houlberg, who at one time held the official
duration record of 89 secs with his machine. The long unrelieved
length of spar projecting forward of the main surface detracts much
from its appearance in the air. A machine of this type should not
weigh more than 8 oz., and is capable of a flight of at least a minute
in duration. The simple 1-1-P¹ type drawn in Fig. 13 was formerly
popularised by Mr. T. W. K. Clarke, of Kingston, who used all-wooden
surfaces, a solid spar and bentwood screw built up in two halves. This
method of screw manufacture is unique, since it enables the two blades
to be prepared from jigs to a greater degree of accuracy than when it
is bent from one piece. Moreover, the lapping of the two halves at the
boss imparts strength to the boss where it is most needed. Fig. 14 is
a type of tractor monoplane very successful for duration, capable of
doing a minute at an altitude of forty feet. The rudder of tractor
machines must always be placed _above_ the thrust line and also above
the centre of gravity, so that should a side gust strike the machine,
the latter does not rock laterally in the air, as a couple is set up
between the underhung load and the rudder.
The winner of the Wakefield Gold Challenge Cup is shown in Fig. 15. It
was designed by Mr. E. W Twining, one of the early experimenters, for
duration, and in the winning flight scored a duration of sixty-five
seconds. It is a very pretty and stable flyer, and will rise from the
ground after a run of about five feet.
[Illustration: Fig. 14.—Tractor Monoplane]
[Illustration: Fig. 15.—Twining Monoplane]
[Illustration: Fig. 16.—Bragg-Smith Biplane]
Fig. 16 is of the Bragg-Smith biplane, which first came into prominence
at Wembley in 1909. The original machine was a huge machine some four
feet in span, possessing a propeller of large diameter, large blades,
and large pitch—quite the antithesis to ordinary practice. Latterly,
however, Mr. Smith has developed his machines into twin-screw, and no
doubt is entertained that even better results are obtained with this
arrangement.
[Illustration: Fig. 18.—Tandem Monoplane]
[Illustration: Fig. 17.—Tractor Hydro-Biplane]
[Illustration: Fig. 21.—Fuselage Biplane]
[Illustration: Fig. 22.—Blériot Type Tractor Monoplane]
[Illustration: Fig. 20.—Tractor Biplane]
[Illustration: Fig. 19.—Twining Hand-launched Biplane]
It should be pointed out, in passing, that this machine is the subject
of a patent for stability, it being claimed that greater lateral
stability is obtainable from the curved lower mainplane. A sketch is
also given in Fig. 17 of a tractor hydro-biplane. This should weigh
about 12 ozs. finished. The tandem monoplane shown by Fig. 18 is
another machine which has scored many successes in the early days of
model aeroplaning at the Crystal Palace. Figs. 19, 20, 21, 22 show the
Twining hand-launched biplane, a tractor biplane built by the writer, a
fuselage biplane (canard or screw behind), and a Blériot type tractor
monoplane.
A tractor machine is one having the screw in front, and a “canard” or
“pusher” machine has its screw behind. It is best to designate the
machine by the type formula. Thus, a pusher monoplane with twin screws
would be a 1-1-P²-0 type. If it had a tail it would be 1-1-P²-1. A
twin-screw “pusher” biplane with or without tail would be 1-2-P²-1 and
1-2-P²-0 respectively. A pusher monoplane with only one screw is a
1-1-P¹ type. A tractor monoplane with single screw is P¹-1-1; a tractor
biplane with single screw is P¹-2-1. If a biplane tail is also used it
becomes P¹-2-2. If twin screws are used it would then become P²-2-2,
and so on.