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Account of Some Experiments on Rigid Airship R.26

Programme of Experiments.———During the summer of 1918
certain full-scale experiments on rigid airships were arranged in
conjunction with the Airship Design Department, Admiralty.
The original proposals included an investigation of pressure
distribution over the stabilizing surfaces of a rigid airship, with
a View to locating the positions on these surfaces where maxi-
mum stresses were likely to be encountered during flight. Airship
R26 was allocated for the purpose, and a preliminary series of
pressure holes was fitted on one of the horizontal surfaces. After
discussion with an experienced pilot a horizontal surface was
chosen in preference to a vertical surface, since it was hoped that
by appropriate alteration both of trim and equilibrium of the
airship during flight, manoeuvres might be undertaken which
would furnish higher stresses over the horizontal fins than would
be secured over the vertical fins by turning manoeuvres.

A semi~circular photo-manometer (containing 32 tubes) similar
in principle to the instrument described in R. & M. 287 was loaned
from the R.A.E. for these special experiments, and installed in
the gun position at the tail. Suitable arrangements were also
made to measure, by aid of an instrument similar to a yaneter
mounted horizontally at the keel cabin, the pitch of the airship.*
A special protractor was fitted to the elevator under test, so that
the true elevator angle at any stage could be Observed directly
from the tail by means of a telescope.

It may be stated at the outset that, owing to bad weather and
to the low disposable lift of airships of this class, these experiments
were abandoned. Some photographs of pressure distribution
were taken on one flight ; but as the ship was flying very approxi-
mately in trim the pressures recorded were insignificant. The
captain emisidered it unsafe to attempt any manoeuvres which
would give high pressures on the fins, and it was eventually agreed
to postpone these special tests until a ship of a later class became
available. ‘