From these words begin
articles and memoirs on plane ANT-25, or as it was quite often named, RD
(a record of range) . Among many Soviet planes ANT-25 is one of the most
well-known. Its history began December, 7, 1931 when under K.E.Voroshilov's
offer the decision on construction of the special winged machine for record
flights on range was accepted. Its creation was assigned to a department
of test aircraft construction of the Central Institute of Aero-Hudrodynamics
(CAHI). The unique machine was projected by a team of P.O. Sukhoi. Andrey
Nikolaevich Tupolev supervised over all works. RD was conceived and constructed
as all-metal one-engined monoplane with low mounted wing of very
big length. The relation of its wing span to a chord exceeded 13!
It was necessary to
gain the maximal aerodynamic quality, which is the relation of lifting
force to the drag. We shall notice, that the wing of planes of that time
incured frequently half of resistance of all aircraft. Before RD there
was no aircraft with narrow and long consoles. Naturally, a wing of such
unusual form was uneasy for design . Researches in this area have made
the whole chapter in a history of Soviet aerodynamics. Constructed as a
result of theoretical calculations and numerous tests, the wing appeared
easy and strong enough to place in it fuel which weight, by the way, made
impressive size of 32 % of the take-off weight. It not only has released
a fuselage from tanks, but also has facilitated a design as weight of fuel
created unloading a wing: the pressure from the aerodynamic forces directed
from below upwards, decreased a cargo working from the top downward.
Among the theoretical
works concerning RD construction, especially interesting and significant
there were researches on vibration of a design. In the literature on aircraft
construction of that time there were instructions that at the big length
a wing there are special vibrations or flatter. This phenomenon arose,
as was found out, at the speed of the flight exceeding some critical speed
strictly determined for the given design. Builders of RD plane were afraid,
that because of the big lengthening this size covered appears very small.
Carefully it was necessary to study the phenomenon. In the CAHI experimental
- aerodynamic department was created special "flatter group". A method
of its calculation did not exist yet. However it was clear, that there
were two ways to the solution of this problem : the first, testing, at
which the special case, RD wing, would be investigated only and measures
of flatter prevention were specified; or the second - development
of the general theory of the phenomenon and on the basis of its results,
suitable for any special case. In the beginning of 30th years M.V.Keldysh
and to his colleagues made possible to solve a problem of flatter in a
general view.
In the completed design
the wing of the record plane looked so: Basic elements - three
longerons and stringers. The cross section of every half-wing consisted
from 18 tubular ribs. First two longerons are connected by six tanks located
between them (the pilot could switch a feed to any tank) and form a powerful
caisson. To the third auxiliary longeron aileron was suspended with
axial and flettner indemnification. Its each half consist of four sections,
fitted by a cloth. Fuel tanks have equipped with drain mouths under a wing.
Their valves opened special explosive devices. Covering of a wing
(except for a zone of a caisson) for rigidity have executed firstly from
goffered aluminium, and after tests have covered it by lacquered cloth
as speed and range of flight appeared below requested because of the
increased drag of a wing. Inside have placed packages with emergency products,
sleeping bags, tent, backpacks, a ski and other equipment which could be
necessary at an emergency landing. With retracted landing gear the plane
had an opportunity to land safely on water and to keep swimming for
some time . For this purpose inflatable cylinders from the rubberized fabric
were stipulated. Junction of wing with a fuselage have closed by
streamline. In area of joints of consoles with centrplane to the first
longeron the main landing gear with oil-pneumatic amortization fastened.
Everyone was supplied with two coupled wheels in the size of 900*200 mm.
They for the first time in practice of Soviet aircraft construction retracted
and extended with the help of electrical mechanism. Gear was powered by
a cable attached to the cylinder. In the extended position gear fixed
with the spring lock. In a flight wheels were half-deep in a wing,
and the external part for reduction of frontal drag and unguided
tail wheel, were closed by cowls.
The fuselage consist
of two parts: a lobby executed at the same time with centroplane, and a
tail of the monocook type. A covering of a fuselage was smooth, duralumin,
with semicircular headed rivets. A cross set - from repoussed frames.
Through all tail part passed four longerons located atop of a covering.
In a forward compartment was placed the V-shaped engine of A.A. Mikulin
design AM-34, 750 hp, forced later up to 874 hp. There were no such
a motors abroad yet.
About reliability
of engine AM Valery Pavlovich Chkalov after flight on island Udd wrote:
the most captious person could not find in it any lack. The crew was convinced,
capacity of the motor appears sufficient for take-off from the ground
this 11-tonns giant. There was no any slightest doubt in reliability of
work of the motor. Anybody from us was not occurred with an idea, that
the motor can hand over and the plane will go on an emergency landing.
And you know, we flied above such places where the emergency landing was
impossible.
Behind the engine
- the cabin with the folding canopy, equipped with all necessary instruments
for flights in complex meteorological conditions. Under legs of the pilot
was small tank for the control for fuel consumption. Right behind a pilot
seat passed a centroplane caisson in which was located reserve oil
tank from which it was possible to fill up with the manual pump a main
tank. Behind a joint of forward and tail parts of a fuselage was equipped
places for navigator and the second pilot, and because of narrowness the
second should be arranged on reserve tank with water.
Fin was carried out
at the same time with a tail part of a fuselage. On it have established
units of fastening of a rudder and the stabilizer with a changeable
angle of attack which covering was goffered. Consoles and fin incorporated
on onboard ribs and were stretched by tapes of the streamline form. To
the stabilizer the elevator with flettner was suspended, consisting of
the two halfs connected by an axis.
Designing of the plane
was completed in the beginning of 1932, and in June its construction began.
Two samples, test and the doubler, subsequently converted in ANT-25-1 and
ANT-25 were created almost simultaneously. Exactly in one year the first
has risen in air. After it the doubler began flights with the engine of
M - 34R (that is with a reducer) . In comparison with test plane the doubler
had some constructive differences. Use of the engine with a reducer has
caused change of the form of a cowl. In a cabin of the pilot for the best
view have increased canopy glass area. Have increased the area of fin,
established different by the form rudders supplied with servo-compensators.
The aircraft was still
not finished, but it was already possible to speak about it as about one
of especially oustanding achievements of Soviet aviation science
and engineering. In 1934 ANT-25 has established some records of the USSR
and a world record of range of flight on the closed route.
Long-distance flights
have begun June, 30, 1934. This day the crew of pilots M.M.Gromov,
A.M.Filin and navigator I.T.Spirin established USSR record for the range
of flight. ANT-25 has flown 4465 kms for 27 ? 21 minutes. In one month
the same pilots have improved a record; for 39 ? 1 minutes 6559 km
were covered, but this result also existed not for long. In September,
flying on a triangle Moscow - Ryazan - Kharkov, a crew of Gromov for 75
? has covered a distance of 12 411 kms, considerably exceeded a world
record of French pilots Bossutro and Rossi. For this oustanding achievement
to the commander of the plane to pilot Gromov, the rank of the Hero of
Soviet Union was given. The new record route Moscow - Franz Josef land
- Petropavlovsk - on - Kamchatka was soon determined. For this flight the
plane - doubler was converted with the improved M - 34R engine with
a tunnel water radiator. Two-bladed the wooden propeller was replaced after
a series of researches by 3-bladed metal with the pitch angle adjustable
on the ground. For cabin adjustable heating an exhaust pipes have
connected to the pipeline laid inside a fuselage.
There were mounted
double controls of plane intended for the control of aircraft during change
of pilots. A forward part of a cabin of the navigator was closed by transparent
canopy with the solar cource gauge. A radio-compass ring eventually was
mounted after all on the bottom of the fuselage and made rotary.
To find a position
of the plane now it was possible by transmittions of any two radio stations.
July, 20, 1936 modernized
RD has made test flight up to Petropavlovsk - on - Kamchatka with crew
of V.P. Chkalov, G.F.Bajdukov and A.V.Beljakov. At the organization
of so distant flight it was necessary to undertake special safety measures.
In particular, Northern and Pacific fleet have received the order to allocate
the on duty ships, Glavsevmorput' has prepared land resque teams. Flight
has passed successfully. Having dropped a pendant above Petropavlovsk -
on - Kamchatka, the crew has decided to turn on a route to Nikolaevsk-on-Amur.
However it was not possible to reach it . Handicap became a strong rain
and a fog. Crew flew just in several meters abowe water. The emergency
radiogramm was sent with the order to land as soon as possible. But
where?.. At last have seen a strip of the ground - the island Udd. Here,
on a sandy shallow, Valery Chkalov, showed the greatest skill and landed
red-winged aircraft. ANT-25 stayed in air 56 ? 20 mines and has covered
9374 km. All world admired with this heroic flight. Our government highly
estimated courage and skill of the Soviet pilots, to all members of crew
the rank of the Hero of Soviet Union was given.
After flight on island
Udd Valery Pavlovich wrote: the aircraft sucsessfully passed all tests...
The plane easily climbed and obeyed the pilot. The machine perfectly behaved
both in a fog, and in clouds, and in conditions of various air streams,
and in mountain district of Yakutia, and at various temperatures. In general
flight opportunities of the plane appeared fine.
Nevertheless, this
flight allowed to estimate some dangers which trapped aircraft of similar
type. In particular, serious difficulties were caused with an icing of
a fuselage, wings and especially the prop. That is why by designers was
in an extra hurry developed in CAHI the first Soviet de-ice system
on the prop.
On natural logic of
events the winged champion was included in number of the Soviet exhibits
of the World aviation exhibition in Paris in November, 1936 and made there
exclusive success.
And in the meantime,
aspiring to the decision new, even more complicated problems, the crew
has addressed to the government with the request to permit a flight by
the route Moscow - North Pole - Northern America. A report of Chkalov,
Belyakov and Baydukov was heard at special session of the government and
has received kindness.
... In the early morning
June, 18, 1937 in 4 h. 5 min. in the Shchelkovo air station was taken start
of this unprecedented flight. The way laid to the north. Somewhere below
under wings for the first time in the world four Soviet researchers drifted
in polar ices: I.D.Papanin, E.T.Krenkel', P.P.Shirshov and E.K.Feodorov.
Further - a novel route, ice and ice... Above Canada the plane has got
in a cyclone. It was necessary to bypass it. Flied at height of 4000-4500
m. Pilots lost forces. It was necessary to be replaced each hour.
Oxygen remained a little. Above Pacific ocean stocks of it have run low.
It was necessary to fall to the ground. At last, after 62 hours of flight
has pilots so Portland. June, 20 in 19 ? 30 mines Moscow time ANT-25
landed at the airfield Baraks near citiy of Vancouver. Unprecedented in
a history of aviation non-stop flight, that tooked 63 hours and 25 minutes
was finished here. Above ocean and ice there were covered 9500 km, some
thousand from them - in blind flight.
Names of heroes appeared
on the pages of newspapers and magazines of all the world. And after only
three weeks the crew of the Hero of Soviet Union of M.M.Gromov has made
one more flight to America through North Pole. The Soviet pilots have established
thus a new world record of range. The plane was in air 62 ? 17 mines, having
overcome distance of 11 500 km.
These historical flights
have shown to all world not only courage, boldness and skill of our pilots,
but also a high level of Soviet aircraft designers.