Evening star., 1946-09-15
British Find Flying
At Speed Of Sound
Is Rough Riding
By {. G.. Shepherd
North Ameriean Newspaper AIlianes


LONDON, Sept. 14-Royal Air
Force flyers who again have broken
the worlds speed record and estab-
lished a new mark of 616 miles an
hour report that flying at any speed
over $50 mph is tough proposition.
Group Capt. E. w. Donaldson and
Squadron Leader w. A. Waterton
the record-breakers, say that even
on a day of smooth air-a great
rarity-the. Gloster Meteors felt like
wooden-wheeled bicycles ridden fast
over cobbleStones. Up to $50 mph
they rode steadily enough, while
above 800 mph they developed sharp
bumps-and all the time the throttles
were wide open, the pilot was ratified
about in the cockpit.
The Meteor was using all the
power it could use. Two Rolls Royce
Derwent V gas turbines, capable of
developing 4,200 pounds of static
thrust-each the equivalent of $4,000
horsepower-had brought the Meteor
to the limit of its performance.
Actual Speeds Vary.
AiiC dtLudl SpStu hlllS blldU
limit will vary with the temperature
of the air, but the relation of that
speed to the speed of sound always
will be the same.
Recently, when an average speed
OF Sis mph was achieved by Capt.
Donaldson. the temperature was low
(about 81 degrees Fahrenheit con-
no Of
down to about 744 mph. If the
temperature had risen to 86 degrees,
the speed Of sound would have risen
to 760 mph., and the average speed
of Capt. Donaldson's Meteor would
have been about 632 mph, using the
same amount of power.
The speed of the Meteor thus
varies with the temperature, but at
any given temperature it remains at
about 81 per cent of the speed of
sound at that temperature. At that
speed, whatever it may be according
to the. temperature of the day, the
Meteor gives the pilot a rough ride
If there were other aircraft so ex-
travagantly supplied with power,
they too would give rough ride.
Planes could be driven beyond
their respective limits if fantastic
amounts of power were used, and
doubtless the structures could be
made strong enough to stand the
strain. The discomfort, however,
would be intense. and eventually the
ability to control the aircraft would
be lost.
Comfort Is Problem
SO long as piloted flight is in
vO!Ved, as distinct from rocket mis-
siles, this question of comfort and
control presents itself. Scientists
believe less difficulty will be en-
countered at speeds beyond that of
sound. The worst troubles occur
near the speed of sound and aircraft
must tackle them not only in &C
celebrating up to, and above the
speed Of sound, but in decelerating
from Supersonic to subsonic speeds.
These troubles arise from refusal
Of the air to flow evenly at the
speed Of sound. They begin at lower
speeds because the air already is
trying to move faster than the speed
OF sound over certain parts of the
aircraft. For instance, air usually
flows faster over the upper than the
lower wing surface 1t, therefore,
may, be moving at the speed of
sound over that upper surface be-
fore the whole aircraft is moving
at that speed.
There often are similar variations
in the speed of air-f1ow over other
parts of the aircraft That hap
pened to the meteor at all speeds
over 600 mph. and explained most
of the bumps. Where the air was
moving fastest, it built itself upI
into shock waves of compressed air
which battered various parts of the
structure, giving the pilot the SEN
sation of riding a bone-shaker over
q rocky road.
Successors to the Meteor are in
sight. Their design and limit should
be nearer the speed of sound. Still
more power already is available. The
Rolls-Royce Meme and De Havilland
ghost gas turbines are rated at S.
900 pounds of static thrust, and are
at the beginning of their careers.