DEVELOPMENT OF THE DFS-301 AND DFS-346 AIRCRAFT TYPES AT ZAVOD NO. 1 PODBEREZYE

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00810A002200140053-4
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 4
• Document Creation Date: December 19, 2016
• Document Release Date: October 11, 2005
• Sequence Number: 53
• Publication Date: September 18, 1953
• Content Type: REPORT

Approved For Release 2005/12/01 : CIA-RDP80-0081OA002200140053-4
CENTRAL INTELLIGENCE AGENCY
INFORMATION REPORT
This Document contains information affecting the Na-
tional Defense of the United States, within the mean-
ing of Title 18, Sections 793 and 794, of the U.S. Code, as
amended. Its transmission or revelation of its contents
to or receipt by an unauthorized person is prohibited
by law. The reproduction of this form is prohibited.
SECRET/CON'T OL.US OFFICIALS ONLY
SECURITY INFORMATION
COUNTRY USSR (Kalinin Oblast)
SUBJECT Development of the DFS-301 and DFS-346
Aircraft Types at Zavod Noe 1 Podberezye
25X1
25X1
DATE DISTR.
NO. OF PAGES
REQUIREMENT
REFERENCES
25X1
18 September 1953
4
25X1
to Plant No. 1 (Zavod 1) in.Podberezye had a workforce of about 1000 persons,,
including 250 to 300 who worked at ORB I, about 220 at OKB II, and 450 to 500
Soviets. There were about 1,800 German engineers and dependents in Podberezyeoi
Except for individual departments which occasionally worked in two shifts, work
was done in.one eight-hour shift.
2a The original DFS,-346.airframe, constructed at Halle, was heavily damaged duripg
the transport and was, therefore, used only for ground tests with.high-frequency
instruments.
30
A remodeled Kranich-type (sic) glider served Wolfgang Ziese as a trainer for
flying in prone position. For safety reasons, a second pilot was sitting be-
hind Ziesee
DFS 01
4. The second test model constructed for the development of the DFS-346 was the
DFS-301 without power unite Measuring equipment, including three string
oscillographs, two batteries, one master compass for inductance indication,
two modified turn and bank indicators which served as angular velocity meters.
and two altitude recorders, was _ installed .in? .the rears. of the plane.. A quadruple
indicator for angle of incidence and for the angle of sideslip besides ; voice
radio. connection to the Tu-2 towing aircraft and to the ground station ..s in-
stalled in the pilot's cabin. The entire measuring equipment had been developed
and constructed at Dr. Wede1s (Wehrle) (fnu) office. The figures obtained by
the osciilogrephs.were evaluated by Erich Steeko
5. The construction. of the DFS-301 was started in Podberezye in late March 1947 and
the plane was completed by early July 1948? The plane was immediately trans-
ferred to Moscow/Salarevo (Teplyy Stan) where it was rigged and where the
wings were mounted, etc. The aircraft made its first satisfactory test; flight
SECRET/CONTROL US OFFICIALS ONLY
(Note: Washington Distribution Indicated By "X"; Field Distribution By "#".)
Approved For Release 2005/12/01 : CIA-RDP80-0081OA002200140053-4
 Approved For Release 2005/12/01 : CIA-RDP80-0081OA002200140053-4
ECR.EP/C0 R.OL US OFFICIALS OULY
I
about 15 August 1948. Then the plane was accep ed by the Soviet dontrol
commission (O'TK Otdel Tekhnicheskogo Kontrolaf who?for three or four
days, until about 20 August 1948, checked the W-301, and installed and.
sealed.the ejector charge (cartridge) which was to effect the launching of
the plane by disconnecting the pipes to release compressed air to the catapult
cylinders. The cartridge was removed in the evening of every flying day and
reinstalled in the morning.
6. After the first testing program, which included about ten flights and lasted
from 20 August 1948 to April 1949, was finished, the aircraft was subjected
to several modifications, K e. boundary layer (fences were mounted) on the
wings and the elevator assembly. During these tests the rigid outrigger
skids under the wing tips were replaced by larger elastic ones which had been
copied from the supporting skids of the Lilly (EF-126), or were dismantled
from the Lilly and remodeled for use with the DFS-301. The second testing;
program included about 20 flights and lasted from July to December 1949.
7. The following modifications were made on the DFS-301 between the first and
second flight testing programs: Boundary layer fencesaconstructed at Zavod 1,
were fitted to the plane after the first flight of the second test program.
Three fences were fitted to each. wing,-bue'70-fo 80 cm from the fuselage, one
about one meter from the wing tip and the third one in the center between the
other -two. One boundary layer fence was fitted.to the under-side of the
elevator assembly on either side of the'aircraft. The installation of the
boundary layer fences had been suggested by the TsAGI Institute. The ex-
tending mechanism of the main landing skid was at first operated by means
of a handOlever, ratchet, and spindle, with a bicycle chain used as trans-
mission between ratchet and lever. This mechanism was replaced by a hydraulic
system, since .too much time was required for the extending procedure. This
modification was also prepared at Za:vod. 1 and the hydraulic system was in-
stalled at Tep.lyy Stan by mechanics of the Zavod 1 assembly department. The
modification work lasted from mid.-May to early June 1949. Holding devices
for the lead blocks, which were to function as counterbalance to the engine,
were fitted to the last bulkhead in the tail of the plane, directly under
the elevator assembly. On Ziese?e request, a loop antenna was installed and
the arrangement and holding device of the antenna mast was modified, because
the original arrangement was too flexible and proved, liable to flutter. A.
window was in each side of the fuselage behindthe pilot, so he was able to
look at the wings. On suggestion of the aerodynamic experts at OXB II, each
wing was lengthened by about one meter. However, the flight, performance of
the plane was not improved by this modification and after two test flights
the wings were reduced to their previous length. In accordance with the ex-
periences gained with the D!FS-301, the wings of the DFS-346 were not lengthened.
All modifications were completed by the end of June 1949.
8. The first flight test program, which was to reveal the flying performance of
the D'FS-301 at ballast flights with different quantities of water in the fuel
tank, revealed exceptionally good aerodynamical properties of the plane. De-
tails on the individual test flights could not be given.
25X1 a maximum speed of 500 km/h was allegedly reached during these tests.
9. During the second flight test program the "OFS-301 was flown with lead ballast
and with the measuring equipment in the fuselage container in operation.. Flights
at an inciinpd angle of the path were allegedly flown at V max 750 km/h (maximum
path speed). The twelfth through fifteenth flight tests were flown with wooden
wings, which were constructed, in Moscow. However, Exenty during the first
flight, these wooden wings vibxs,ted so villent,ly that the connecting bushings
were deformed to oval, shape. The bushings had to be ground and the bolts had
25X1 to be provided with chromium plating. these wings were
very poor in quality; particularly the glued joints were very defective. Between
the first and second test flights with the wooden wings the aircraft was checked
by the control commission and was released for further test flights after the
bushings and bolts were overhauled. After the third test flight the wooden
wings were finally dismantled and the project was never mentioned again.
SECFET/COITTFOL US OFFICIALS ON1'.;Y
Approved For Release 2005/12/01 : CIA-RDP80-0081OA002200140053-4
 Approved For Release 2005/12/01 : CIA-RDP80-00810A002200140053-4
SECEET/Cc TROL .uS OFFICIALS ONLY
-3-
25)(1
25X1
25X1
the flying performance of the DFS-301 during the second test
was excellent. The boundary layer fences, the modifications of the
.
program
extension mechanism of the main landing gear skid, the remodeled outrigger skids,
as well as the measuring equipment, proved.to be a-successes Aerobatics were
not included in the testing programs. It was difficult to get the DFS-301
spinning. In stall condition, the aircraft vibrated and then leaned over to
the noses seldom flown an aircraft of such excellent
stability. All modific.;tions experienced with the DFS-301 were utilized for
the design of the DFS-3)460 Furthermore, the PPS-346 was equipped with an ad-
justable elevator assembly, with limit switch which was to be controlled by
an electrically operated spindle, because the control pressure of the DFS-301
was apparently too strong. The electric motor used for this control system.
was a:.tz i9.20O'$ att flywheel starter engine, 'hich was to drive the spindle via
a transmissions The shoes of the pedal operating the vertical rudder had also
to be modified, becauserF- when catapulting out one might get
stuck with the tip of the foot. Another modification accomplished on the
DFS-346 on the basis of the experiences with the the IFS-301 was the
locking device of the canopy which, with the DFS-301 could only be opened
from the.outside by means of a bowden cable through a hand flap. The canopy
of the DFS-346 could be opened by the pilot from insides
110 After the second test program was completed, the DFS-301 was covered with
tarpaulins and sealed and remained at `Tep.l.yy Stan.n
became of the aircraft o
It was not known what
DFS 146
12 0
25X1
25X1
130
25X1
The flying program with engines was to start in spring 19510
25X1
r DeTlovou Q , MIUKC
September 1950, the aircraft was not subjected to Hy modifications
Three identical test models of the DFS-3146 were simultaneously under con-
struction. Work on the wings and the fuselages was started in about September
1948, while the assembly of test model No. 3 was started by January 1949, and
completed by late February 1949. In early Mbarch, test model No 0 2 was sub --
jected to vibration tests. The plane, suspended from rubber ropes, had a
Leonard engine installed in. the wings o '.'h.ese tests lasted about, two weeks and
terminated between 20 and 25 March0 Testing had to be done at night, because
during the day the electric current was too weak or failed completely. Ac-
cording to the experiences gained in the vi'bration tests, the bulkhead in the
fuselage, about 20 cm. behind the leading edge of the wing, had to be reinforced.
Further modifications on fuselage and wings were not necessary. The model was
then transferred to Teplyy Stan for gl.id.i:ng t,vests q with lead ballast in the
tail and a Tu-4 acting as tow-plane. This test program. was continued until
July 19500 The model was then returned to Zavod 1 and parked in a hangar. 25X1
001g nnnp~yarp the ski6s of nta, model Nos of the D'FS- 46 damaged,
e
and. landed outside of the airf.ie.lda Experimental model woe was comp le
eight to ten days later than :boa 3. After the airframe had been assembled the
engine was installed. Including the density tests for the pipes and containers, this
procedure. required 'two days. Then the wings were dismantled again and the
fuselage with engine was shipped to the engine test stand of Zavod 1 for static
thrust tests, etc e The tests lasted two weeks and were completed by late
March 1950. Then the wings were packed. in canvas-covered crates and the fuselage
was covered with tarpaulins and sealed by the control commission. The aircraft
'was ,ready to be shipped to another airfield because Teplyy Stan airfield beca;ne
boggy in rainy weather, and the landing on steel matting seemed too-dangerous
meat; Bans Motech, as flight administrator; Erhardt Sczuka, as chief mechanic;
and an undetermined engineer from. -the Mantey Group. During summer 1950, ex-
perimyntal model No. 1 way assembled in the same way as the other two models,.
tested at the engine test stand, and stored as a reserve.
The testing team was to include Ziese; Erich Steek, for the measuring equip-
SECRRT/COUTROL US OFFICIALS Mlzrf
Approved For Release 2005/12/01 : CIA-RDP80-00810A002200140053-4
 Approved For Release 2005/12/01 : CIA-RDP80-00810A002200140053-4
SEM.TJ 0NTR.OD . US OFFICIALS ONLY
O
25X1
A-
14. For test flights, the DFS-346 was towed by a `.''u-+ which climbed to any altitude
of about 10,000meters, from where the DFS-34+6 was catapulted to glide down.
15. The power unit for the IMPS?3l6, assembled at the engine department under
the supervision of Kurt Schell and Herbert; Ufer, absolved its State test in
January 1950. By this time, three complete double-engines had been completed.
Each double-engine reached a, total output of 3,000 to 3,500 kgp, but never
4,000 kgp. The double engines were fueled with "T-Stoff" and "C-Stoff" and
included nine steps. Each engine could also be operated individually. The
pumping turbine rotated at 18,000 to 24,000 rpm. The longest test run lasted
2.5 minutes. The containers for the T and C-Stoff were pure aluminum.
Dr. Wede's Office
16. The office and laboratory headed by Dr. Wede (fau) manufactured instruments for
the test flight program, suchas9 measuring instruments for angles of incidence,
angles of side slip, acceleration meters, extensometers, and tension indicators.
Up to about 30 extensometers and tension indicators had to be manufactured for
the TsAGI Institute per month. Also other instruments of this kind had to be
continuously delivered in small, series to TsAGI and ,other Soviet offices. These
instruments had first operated with potentiometers functioning as pickoffs;
however, because of the difficulties encountered in the supply of wire,, they
were converted to operate on an ind?.ction basis. The instruments were packed
25X1 in boxes and picked up by officers who arrived in sedans.
25X.1
25X1 1. commmentt
0PN 'o. a a workforce of about 500 German experts and about
25X1 3D5O3 Soviets. Also Othe German group with dependents included about
25X1 1,500 persons.
25X1 2, C The English translatioL, for tIK is Technical Control
sec t, ora'
SBG,R t/COM ROL, US O,F;FICIATS o;NIY
Approved For Release 2005/12/01 : CIA-RDP80-00810A002200140053-4