SAAB SONICS - AVIATION PUBLICATION

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00926A000800030024-6
• Release Decision: RIPPUB
• Original Classification: R
• Document Page Count: 28
• Document Creation Date: December 19, 2016
• Document Release Date: December 18, 2006
• Sequence Number: 24
• Publication Date: December 30, 1948
• Content Type: REPORT

Approved For Release 2006/12/19: CIA-RDP80-00926AO00800030024-6
Approved For Release 2006/12/19: CIA-RDP80-00926AO00800030024-6
 Approved For R81ea'se 2006/12119: CIA-RDP8 }-00926A000800030024-6
&*% S~bILS
SVENSKA
AEROPLAN AKTIEBOLAGET
SAAB AIRCRAFT COMPANY'
LINKOPING, SWEDEN
Publisher: RAGNAR WAHRGREN
('Editorial Director: ARNE KRABBE
Editor: OVE SCHULZE
No.l 3 JULY-SEPTEMBER 1948
CONTENTS
page
Arnle Krabbe: Saab Safir -the gem
of the air ....................... .2
Anders Widengren: Technical. edu-
cation
Editorial ...................... 8
Sven Svensson : Temperature. measu
rements from aircraft 9'
Rep'ort: A new Saab invention..... 14
Aarne Lakomaa: The Scandia's
engine installation .............. 16
Arne Svensson: Technical develop-
ment work in the Saab workshops '20
Cover picture: Ethiopian cadets familiarise
themselves with the instrument board of the
Saab,, Saf it (see article on the Safir on page 2)
(Photo: E. Lundqvist)
On the right: Unconventional view of the Saab
Scandia
(Photo: A. Svenberger)
Classification summary for the technical artic-
les is to be found on the third page of the cover
Printed in Sweden by Oscar Isacsons Boktryckeri All,
Goteborg 1948
Approved For Release 2006/12/19: CIA-RDP80-00926AO00800030024-6
 App ved For Release 2006/12/19: CIA-RDP80-00926A000800030024-6
-
AA8 5~NI[5
Three Saab Safirs are flown to India for delivery
Saab Safir
the Gem of the Air
by
A r n e K r a b b e, Saab's Public Relations Manager
Safir - the gem of the air -, is a proud
attribute, a name involving obligations and one
to which the glittering little machine is fully
entitled.
Work on the design was commenced in 1944
and in 1945 the Safir was flown for the first
time. With three years of existence behind it,
it is still in the youthful stage. but notwith-
standing this fact a considerable advance can
be claimed on its behalf and it is already
responsible for a notable chapter in the history
of flight.
The Royal Swedish Air Force has purchased a
number of Safirs for use as staff- and liaison
planes, in which service the machine has met
with the highest appreciation. However also
private aviators in Sweden began to interest
themselves in the plane and very soon disco-
vered that the Safir
purposes. The first
for sporting and business
private flyers to purchase Safirs were Mr. Uno
Ranch and Mr. Giista Fraenckel, both of whom
became Safir enthusiasts of the first rank. Mr.
Mr. Arne Krabbe
 -Approved For Release 2006/12/19: CIA-RDP80-00 6A000800030024-6
5
AA%S1Wa
Ranch moreover caracterises his first encounter
with the Safir as "love at first sight" and
,,a love that is never betrayed ". Mr. Ranch
and Mr. Fraenckel have both toured round
Sweden in their Safirs since 1946, but their
flight log-books also include trips to the Con-
tinent of Europe, primarily England. At the
present day the Safir can be found in many
parts of Sweden and thanks to the A.B. Central-
flyg which employs the plane for taxi flights
and circular tours, the machine has now visited
most places in the country. The interest
displayed in Europe for the plane has been
considerable. The machine delivered to Mr.
Michael Christie in London has been tested by
English experts and the test pilot, Maurice A.
Smith, has expressed his impressions concerning
it in an article published in " Flight " of the 23rd
October 1947. His report was of such a favour-
able nature that Saab's sales department is now
glad to enclose copies of it with their quotations.
As early as the end of 1946 however, a be-
ginning was made with the exportation of the
Safir to countries beyond the boundaries of
Sal it passengers from
the Pole Circle to the
Equator. Above, the
Safir is being boarded
by a representative of
the nomad tribe, the
Lapps, and on the right
Ethiopian crews are
waiting to pilot four
Safir planes from Stock-
holm to their distant
homeland
Europe. Ethiopia was the first customer and
the plane purchased by the Duke of Harrar
was flown on delivery to Addis Ababa by Saab's
chief test pilot, Captain Claes J. Smith. The
impression made on the Ethiopians by the Safir
was so favourable that a division of Safirs was
flown to that country in 1946 to be incorpo-
rated in the Imperial Ethiopian Air Force as
school- and training planes. Deliveries to
Ethiopia reached their height when the chief
of that Air Force, Count Carl Gustaf von Rosen,
took over a further Safir in which he made his
world-famous non-stop flight Stockholm-Addis
Ababa on the 9th May 1947.
South America is an extremely air-minded
continent and the Safir is of course represented
there also. It has found enthusiastic friends
both in the Argentine and Brazil. I have seen
reports of test flights which resemble drafts
for propaganda purposes rather than test
reports. It is my belief therefore, that the
Argentine and Brazil merely constitute the first
stage of the South American market. Europe,
America and Africa, these only represent three
parts of the world. Now however, barely three
years after its birth the Safir has also con-
quered Asia. On the 27th April 1948 three
Safirs started from Sweden, the destination of
one of which was Bombay whilst that of the
other two was New Delhi. This delivery flight
has now been completed and the Safir has, thus
been introduced in four parts of the globe. With
this achievement the pioneering period of the
plane may be said to be terminated. Delighted
Safir owners undoubtedly represent the best
means of introducing the machine since they
are strongly in favour of others becoming
owners of a Safir - the gem of the air.
11111211111111 INS I
I
I 110W NON
a
 Ap ved For Release 2006/12/19: CIA-RDP8Q-00926A000800030024-6
AA% S?NILS
TECHNICAL
EDUCATION
by
Anders Widengren
Principal of Saab's Technical
Training School
The greatest importance has at all times been
attached to the combination of practical skill
with theoretical knowledge. Just as an indu-
strial undertaking upholds its position against
competitors through the organizing capacity and
inventive genius of its engineers, so must it base
its future existence on the individual skill of its
workers. Notwithstanding all available technical
resources, specializing and mechanisation which
is replacing manual work by machinery to an
ever increasing extent, the metal industry has
been unable to dispense with the services of
competent and skilled workmen. It is essential
for high quality production such as that of Saab
that an ample supply of skilled labour should
be available. Even in the early days of the com-
pany difficulties were experienced in obtaining
competent workmen in sufficient numbers. In
the circumstances it was very natural that Saab
should take upon itself the work and expense
of providing a technical training on systematic
lines. A step in this direction was taken before
the outbreak of the World War II, when the
"assembly training school " was started. The
course in this school extended over a few weeks,
and in addition to a practical training in all
forms of assembly works, newly engaged sheet
metal workers were also able to obtain a few
days theoretical instruction. But Saab did not
rest satisfied with this rapid training course
alone; they went the whole length and in the
late summer of 1942 the doors of Saab's techni-
cal training school were opened to receive the
first batch of student apprentices.
During the first four years of its existence
the school. was located in rented premises out-
side the Saab factory area. On the completion
of the underground factory, however, space
4
became available within the Saab works and the
school was able to move into its present quar-
ters. These are located in a bay of one of the
erecting halls and are entirely separated from
the other workshops. The rooms are light and
airy andl are suitably equipped for the requiere-
ments of the school.
The Task of the Technical
Training School
is to train up apprentices to become proficient
fitters and machine operators in our workshops
by giving them a sound grounding in both
practical and theoretical subjects. On this
account the instruction is planned on lines
adapted'; to Saab's production and organisation.
Furthermore, the activities of the school faci-
litate the recruiting of works foremen to some
extent. The leading workmen and foremen. are
selected amongst the most competent of the
apprentices when the latter after completing
their course have been out in the workshops
for some years and have proved themselves
suitable for such advancement.
The period of training lasts for 4 years.
Mr. Anders Widengren
Approved For Release 2006/12/19: CIA-RDP80-00926A000800030024-6
 -Approved For Release 2006/12/19: CIA-RDP80-00 A000800030024-6
Practical instruction is given in spacious light premises in which the In the subject the theory of engines,
apprentices learn to operate the different machines under expert- amongst others, the boys must dismantle
supervision and re-assemble an aero-engine
New pupils are taken in each year, and
the number of apprentices attending the school
is about 60. The minimum entrance age is 14
years, the maximum age being 16, but in excep-
tional cases youths who have already turned
17 are accepted. The maximum age limit has
been set as low as 16 for the reason that we
wish the apprentices to remain in the school
for at least 4 consecutive years without being
obliged to interrupt their training on account
of military service. It is also undesirable to
allow too long an interval to elapse after they
have finished their ordinary school education.
From the point of view of instruction also it
is preferable that the difference in age between
pupils in one and the same class should not be
too great. Other conditions for acceptance as
an apprentice are that the applicant must have
reached at least the 7th class in the Elementary
School, and that he is passed by the doctor as
fit ' for work in the shops.
admission Tests
Applications for admission to the school must
be received approximately six weeks before the
beginning of the new school year, which starts
immediately after the works holidays. After a
preliminary thinning out which is based on the
applicant's school-leaving report - particularly
with respect to mathematics, grammar, drawing
and handicrafts - the youths selected in this
manner must undergo an examination both of
a theoretical and psychological nature.
The theoretical tests are two in number. One
of them comprises a few simple calculations
and in the other the applicant is required to
read some suitable passage aloud and then
reproduce it in writing.
In the psychological test the so-called " Minne-
Practical and theoretical training always go hand in hand.
A lesson in machine drawing is in progress here. The
film projector and ballopticon, both of which are em-
ployed in teaching, are visible in the background
sota Tests" are applied. For these tests two
"batteries" are employed, each containing two
modelling boards, a sheet of paper for form
division and a tool assembly box. The test with
the modelling boards is carried out by asking
the boys to transfer a number of sawn-out
wooden blocks of different shapes with one
hand from the cut-out portions in one board
to those in the other and from the latter back
again to the first as quickly as possible. The
cut-out portions in the two groups are arranged
differently. Figure division consists in allowing
the boys to attempt for a quarter-of-an hour
to divide up as many of the unitary forms shown
on the sheet as possible into the separate forms
indicated at the side of the unitary forms.
Finally, the assembly tool box contains tools
and other articles of a practical nature which
have been taken apart at the beginning of the
test. These articles must be re-assembled satis-
factorily in the shortest possible time. The
results of the three tests are combined and a
5
 Ap ved For Release 2006/12/19: CIA-RDP80-00926A000800030024-6 -
5
At % SW[S
final number of points awarded in accordance
with certain formulae.
The two theoretical tests are preceded by a
simple oral text in which certain questions -
which might be called" intelligence questions"
- are put to the applicant. Attention is also
paid to the boy's general deportment.
The 15 boys passing this examination most
satisfactorily are allowed to enter upon a 6
months trial period during which their aptitude
is the subject of further observation. If this
trial period is found to yield satisfactory results
both for the company and the apprentice, a
4-year contract is exchanged between Saab on
the one hand and the apprentice and his
guardians on the other. Thus the contract
expires with the termination of apprenticeship
and the new craftsman is at liberty to enter some
other concern if he so desires, though Saab of
course prefers that he should remain with the
company.
Instruction
Practical instruction naturally fills up the
greater part of the training time. During the
two first years the apprentice is trained exclu-
sively on the school premises in which, in addi-
tion to work-benches, the following machines
are available: 4 lathes, 1 bench lathe, 2 turret
lathes, 2 shapers, 3 milling machines, 1 tool
grinding machine, 1 universal cylindrical grin-
der, 1 four-spindle drilling machine, 1 pillar
drilling machine, 1 band saw, 1 hack saw, 1
contour saw, 2 (double-ended) grinders, 1 screw
press and 2 bench shears. In the third year
the apprentice is placed out in the shops where
he is moved from one department to another
in order. to obtain as wide an experience as
possible, and he can at the same time learn
to find his way about in the Saab works. He
is still under the control of the training school
however.
The three years' basic instruction includes,
on the average each year: bench work, tracing
and drilling 25, 20 and 15 weeks during the
first, second and third year respectively, turn-
ing 10 weeks, milling, shaping and grinding
5 weeks each, tool-room service 5 weeks during
the second year, control and measuring 5 weeks
in the third year and welding 5 weeks during
the third year. Only in the fourth year may
the apprentice begin to specialize in the branch
that appeals to him and for which he is suited.
This transference to a definite branch of work
4?
)
Slide films are found to be a very effective supplement
to verbal instruction
is preceded by a comprehensive discussion
between the teaching staff of the school, the
workshop management and the apprentice
himself. Satisfactory guidance is offered in
this connection by the continous record kept
of the apprentice's capability and behaviour
and the, interest he has shown. Obviously it
is extremely important that the trained workman
should be employed on the work for which he
is best suited, since only under such conditions
will the training yield the best results for
himself and the company.
The weeks spent on the machines and at the
benches'iare not arranged consecutively but are
divided up into short periods. In this connec-
tion investigations have shown that a training
which allows various repetitions achieves the
desired end more quickly and yields more per-
mament results than is the case, when each
subject is dealt with in a single sequence. More-
over, practical instruction is so arranged that
during the early days the apprentice can carry
out certain practical exercises in each branch
of work.i Thus a series of exercises of increasing
difficulty have been prepared for filing, turning,
etc. At' the end of a certain period the length
of which depends upon the apprentice's ability
and interest, he is allowed to begin work on
some of the parts required in production. Pro-
ductive work is encouraged to the greatest pos-
sible extent since it is the value of such work
that helps to balance the costs of running the
school. It is of advantage moreover, that the
apprentice while still in the school should
become acquainted with the tasks he will
Approved For Release 2006/12/19: CIA-RDP8b-00926A000800030024-6
 Approved For Release 2006/12/19: CIA-RDP80-009 A000800030024-6
SAAB 5W[S
encounter at the work benches and machines
out in the workshops, to say nothing of the
satisfaction and creative pleasure he experien-
ces in making a product that will be actually
employed.
The apprentice is also allowed to complete
his tool set for which he has signed a receipt,
by making centre punches, scribers, chisels,
screwdrivers, squares, inside- and outside calli-
pers, etc. himself. These tools become his
own property on the conclusion of his training.
The theoretical instruction imparted by the
school's own teaching staff is restricted entirely
to the daytime, and is carried on during the
first three years for approximately 40 weeks
each year. It includes the subjects of work-
shop technique, the theories of materials and
machines, technical calculation, drawing, the
theory of aeroplanes and engines, grammar and
citizenship, also lectures on time studies, indu-
strial economy, hygiene, and industrial and
labour legislation. The lectures are held by
members of Saab's staff dealing with such mat-
ters. In addition, the school radio is used as
an auxiliary to the instruction which is further
supplemented by educational films. For the
latter purpose the company's light projectors
consisting of a 16 mm film projector, a strip
projector, sciopticon- and ballopticon appa-
ratus are available. No theoretical instruction
is given during the fourth year. In place of it,
the apprentices must give a discourse on some
subject with which they have come into contact
and which particularly interests them. Their
audience consists of their comrades and the
school teaching staff. Finally, it may be men-
tioned that the apprentices are allowed to make
visits to other works as a part of their educa-
tion. In addition, the fourth class go on a
longer study trip on the completion of their
training.
The number of hours devoted to theory is
8 in the first class, 6 in the second class and
4-5 in the third class. Apart from the fore-
going, 2 hours are set aside for gymnastics and
sport in the first and second classes and one
hour for the third class. This covers a total
of 740 hours theory and 200 hours gymnastics
and sport during the whole course of training.
This instruction schedule may appear somewhat
too comprehensive at a first glance, but the
740 hours of theory only represent 7.5 % of the
total working time during the four years.
On completion of the four-year course the
apprentice receives a leaving certificate with
a report on his competence and skill, and in
specially deserving cases a diplome is awarded.
On the basis of this report and the observations
made concerning the apprentice during the
fourth year he is finally placed in the works
in the position for which he is found most
suited.
Advantages
The instruction is given entirely free of
charge and the apprentice receives and hourly
wage both during the theoretical and practical
training. At the present time remuneration is
at the rate of 36 Swedish ore for the first half-
year, increasing successively by 5 to 6 ore for
each half-year, so that the apprentice receives
an hourly wage of 76 ore during the eight half-
year to which an emergency supplement is
added in accordance with the current index
figure. On drawing up the contract, moreover,
a sum of 192 Swedish crowns is placed to the
apprentice's credit in a savings bank book. This
sum, together with a " renumeration for dili-
gence " - 4 ore per working hour - amounts
to about 600 crowns, and is placed at the pupils
disposal as a bonus after he has passed through
the school. From and after the seventh half-
year the apprentice may be placed on piece-
work where this is feasible.
The company's interest in the apprentice does
not cease on the conclusion - of working hours,
but also embraces his leisure time. Thus, on
two evenings a week the school premises remain
open for leisure-time occupation, which affords
the apprentice an opportunity of cultivating his
particular hobby. The company has also pre-
sented the school with a building. set for a glider
plane which is now being assembled in the Lin-
koping Flying Club's premises under expert
guidance.
The school also has a club of its own, the
Training School Sports- and Social Club (YIK)
the purpose of which is to increase the interest
in gymnastics and sport and foster good com-
radeship. The business of the club is managed
by the apprentices themselves under the super-
intendance of one of the school's instructors.
In this way the apprentice can also obtain an
insigth into the business of club management.
In the education of pupils attending the Saab
technical training school an endeavour is also
made to form the pupil's character and educate
him to become a good and responsible citizen.
7
 fA oved For Release 2006/12/19: CIA-RDP80-00926AO00800030024-6
5
aaa 5aaiI5
The three Saab Safir planes which started
from Sweden on the 27th April with India as
their destination landed in New Delhi on the
7th May according to program, only two hours
later than the estimated time - a fine perfor-
mance both on the part of the pilots and the
planes.
The leader for the trip, Captain Anders Helg-
strand, has returned to Sweden by ordinary
traffic plane, and has nothing but good to say
of the Safir's behaviour during the long journey.
The Saab Scandia has now flown for a total
of 350 hours during the testing period, 196 hours
of which have been flown. after the overhauls
and modifications carried out last winter.
In the middle of May a test flight was made
in the form of a flying visit abroad. The air-
craft first flew from Linkoping to Oslo, and on
the following day to Newcastle in England.
After a stop of two hours, at the latter place
the plane flew back direct'to Linkoping. This
is not the first occasion on which the Scandia
has made a trip abroad. Visits have been paid
to Denmark, Holland, Belgium and Switzerland
at an earlier date.
The interest of the, Norwegian and. Danish
Airlines in the Scandia has been shared by the
Finnish Aero O/Y, the chief of which visited
the Saab Works in April for the purpose of
studying the Scandia.
Interest in the Swedish traffic plane has also
been exhibited outside Scandinavia however.
Two prominent members of the Dutch Airlines,
the KLM, paid a visit to Saab in April and in
May a demonstration with the Scandia was given
S
at Bromma, Stockholm, for the director of the
Swiss Airlines "Swissair" and the head of the
Swiss Air Traffic Board amongst others.
civil planes represented the chief
source of'i interest for two representatives of the
Air Services of India who honoured Saab with
a visit in June. Exhaustive demonstrations
were given both with the Scandia and the Safir
for these visitors from a distant land.
In July Saab had the pleasure to see a repre-
Gentativel of the Belgian Airlines " Sabena " as
their guest at Linkoping. The visit, of course,
was primarily made in order to study the
Scandia.
The "Thulin Medal" - an outstanding Swe-
dish distinction for aviation research work,
instituted in 1944 - was awarded in May this
year to F. Wanstrom and A. J. Andersson, both
employees of Saab. The medal has only been
conferred on one previous occasion.
On the 19th June a Saab engineer held a
discussion for his doctorate, under the title
"Stress distribution in aeroplane shell construc-
tions" and the sub-title "Some methods for the
determination of the stress distribution in aero-
plane shell constructions and with special consi-
deration to the stress distribution in flat or slight-
ly curved shells ". The man on whom the title of
"doctor ,' has just been conferred is Thorkild
Rand and the investigations for his doctorate
were undertaken in connection with work car-
ried outfor Saab relating to investigations con-
cerning ',increased strength problems for aero-
plane shells.
The value of Dr. Rand's investigations will
be appreciated from the fact that by means of
the new' methods the same calculations, which
formerly occupied 8 men for a period of 8
weeks, can now be completed by one man in
I ~1:2 weeks.
Approved For Release 2006/12/19: CIA-RDP80-0092FiAOOO8oOo ifn24-n
 Approved For Release 2006/12/19: CIA-RDP80-00926AO00800030024-6
AAB S~HI[S
Temperature Measurements
from Aircraft
The accurate measurement of the temperature of the external air is a
matter of considerable importance in flying tests, particularly when flying
at high speeds. The instruments hitherto available for the purpose have
been found somewhat unsatisfactory and Saab has consequently developed
a temperature recording device of its own. In the following pages Mr.
Sven Svensson who has been engaged on this work describes the
problems associated with this special measuring equipment.
. The rapid development of high speeds for
aircraft has given rise to the need for tempe-
rature recording apparatus which can record
the actual temperature of the high-velocity air
currents. It is essential to know the tempera-
ture of the external air in order to calculate
the performance of an aeroplane with the
assistance of the test flight results. The tem-
perature may vary with great rapidity in the
course of certain tests such as nose-diving for
example, so that in addition to indicating an
accurate static value, the temperature recorder
must also be able to follow the changes closely.
An accurate temperature recorder is required
in numerous other cases, and in some instances
its dimensions must be as small as possible in
order to reduce the disturbances of the air
current. In all probability the need for accu-
rately determining the temperature of the
discharge in jet planes will assume a constantly
increasing importance. The problem to be
dealt with here relates to great speeds in com-
bination with high temperatures.
Principles
A. measuring element placed in a gas flowing
at a high velocity indicates a temperature that
is higher than the actual temperature of the
gas. The increase in temperature is due to the
heating up of the gas on compression and
friction against the measuring element (friction
is a slowing down of the gas layer nearest to
the measuring element - the boundary layer
- and is thus of the same character as com-
pression). According to the principle of energy
the temperature rise on the slowing down of a
mass of gas is solely due to the velocity of the
gas before and after the change of velocity and
to the exchange of heat of the gas with its
surroundings. In air this rise may be as much
as 45? C at a speed of 300 m/s. The same
conditions apply also when the slowing down
is caused by friction, since the innermost por-
tion of the boundary layer will also become
entirely stationary. When the measuring ele-
ment is placed directly in a gas flowing at a
high velocity the temperature rise will be less
than if the gas were slowed up immediately in
front of the measuring element which is the
case when using a so-called " staudruck " ther-
mometer. This is not due to the different velo-
city of the gas nearest to the measuring element
but to the varying relative heat exchange with
the surroundings of the gas which has been
completely arrested. The heat exchange in
turn is dependent both upon the form of the
measuring element and recording device and
upon the condition of the gas density etc.). In
this respect the height above sea level influen-
ces temperature measurements made from air-
craft and this is particularly noticeable with
the friction thermometers which were usually
employed hitherto. In view of the difficulty
of determining the influence of the height,
thermometers of this type are not sufficiently
reliable for the accurate recording of tempe-
ratures.
The provision of a thermometer entirely free
from correction, by producing a vacuum that
varies with the velocity seems to be impossible.
9
flrwr+rr,t,cd ~nr Palaaca 9nfA,/17/1a . riv-RnpRri-nnagrnnnnpnnn-inng4-F
 Approved For Release 2006/12/19: CIA-RDP8
AA? MRS
Gas to be measured
insulating gas Cover of insulating material
Measuring a ement (thermal element or resistance wire)
Fig. I and 2. The insulating temperature recorder
developed by Saab, shown diagrammatically
above and in its finished form below. The
small recorder has a thermal element, and the
large one a resistance wire as the temperature-
responsive member
Simultaneously with the reduction of pressure,
the density is also reduced and the pressure
can only influence the correction through
variation of the heat exchange with the sur-
roundings. Difficulties are likewise encountered
in attempting to form the temperature recorder
in such a way that the heat given off to the
surroundings counteracts the temperature rise;
the dependence upon height and the factor of
uncertainty may be relatively great.
The actual temperature of gases flowing at
a high velocity may also be determined directly
by means of radiation methods which, however,
are probably not so reliable at low temperatu-
res. Furthermore, there is some difficulty in
applying these methods during flight tests.
In these circumstances Saab decided to
employ a temperature recorder the measuring
element of which is placed in the gas current.
The requirement in this respect was to produce
a form which allows as little exchange of heat
with the surroundings as possible in the gas to
be measured without at the same time rendering
the recorder too complicated.
The form of the recorder necessary to meet
these requirements is dependent to a great
10
extent upon the conditions prevailing during
the measurements. A sufficient quantity of gas
must of course be slowed down for the greater
part in front of the measuring element, that is
to say, the so-called " staudruck "-principle
must be a1pplied. But for measurements carried
out in the hot discharge air of a jet plane for
example, where the chief heat exchange with
the surroundings takes place by radiation to
the cold adjoining walls an entirely different form-
is required than is the case when measuring
the temperature of the external air during
flight. In the latter case the radiation -
usually consisting mainly of solar radiation -
is of a very much lower order of magnitude
than in the first-named instance. According to
preliminary calculations and tests carried out,
a temperature recorder constructed on the prin-
ciple illustrated in Fig. 1 will allow sufficiently
accurate insulation of the gases to be measured
at the temperatures and radiation commonly
encountered when measuring the temperature
of the external air.
The Adiabatic Correction Curve
A temperature recorder the heat exchange of
which with the surroundings can be neglected
has a so-called adiabatic correction curve. Fig. 3
Increase in temperature according
to the i`staudruck principle"
30
(ot = 4,97 [100] e)
7?
X Value obtained with
recorder in accor-
dance with fig. 1
0 Value obtained with
recorder equipped
with 1 insulat-
ing cover only
100 200 300
Velocity of undisturbed air in relation to the recorder
Fig. 3. The adiabatic correction curve for dry air at
about + 70? C and a pressure below 2 atmosphe-
res. The values indicated have been obtained
during tests with the thermometer centrifugal arm
in Fig. 4. Temperature recorders partly designed
in accordance with Fig. I and partly equipped with
a single insulating cover have been employed here
Approved For Release 2006/12/19: CIA-RDP80-00926A0008000:10024-6
 Approved For Release 2006/12/19: CIA-RDP80-00 A000800030024-6
5
NSWIS
Fig. 4. Thermometer centrifugal arm with which a peri-
pheral speed of nearly 300 m/s can be attained
shows a curve of this kind for air, applying
to temperatures round about 00 C. The curve
is dependent upon the specific heat at constant
pressure (Cp) of air which varies with the air's
pressure, temperature and moisture content.
The effect of the pressure may be neglected
below 1 to 2 atmospheres, that is to say, the
conditions usually encountered during flight,
and similarly, for dry air, the effect of the
temperature with the temperatures of ? 700 C
commonly occurring may be overlooked. At
high temperatures however, the correction
curve will be changed - at + 150? C the devia-
tion will be 1 % and at + 800? C about 15
from the curve illustrated.
The effect of moisture under ordinary flying
conditions may, generally speaking, be neglec-
ted up to the point of saturation. Above this
point the curve shown in Fig. 3 will not apply
as the heat is then absorbed in the vaporisation
of a part of the water. On this account where
accurate information regarding the tempera-
ture of the external air is required, flight tests
should not take place in clouds charged with
moisture for example, even in cases where
these are not otherwise detrimental to the test.
From what has been said above it will be
realised that the correction curve shown applies
to air at the pressures and temperatures which
may be encountered during flight provided that
the moisture lies below the saturation point.
Measuring Equipment
Either a thermal element or a resistance wire
may be employed as the measuring element. A
thermal element possesses the advantage that
Fig. 5. Temperature measurement with Saab's recorder
placed in the air jet flowing from a container. The
interchangeable nozzles are shaped to allow adiabatic
expansion of the air jet
it occupies little space so that the dimensions
of the temperature recorder may be kept low.
For the accurate measurement of slight diffe-
rences of temperature however, highly sensitive
instruments are required for recording the
thermal forces. Apparatus of this kind is
usually somewhat clumsy and therefore unsuit-
able for flight tests. The resistance wire in its
turn necessitates a somewhat larger tempera-
ture recorder but does not otherwise entail the
use of special measuring instruments. In the
recorders developed by Saab a resistance wire
is used almost exclusively - usually consisting
of a special, pure nickel wire. The effect of
the temperature on the resistance wire is as a
rule measured by means of a crosscoil instru-
ment the relative insensitivity to voltage varia-
tions of which renders it possible to employ
the d. c. voltage of the aircraft system. It is
necessary to connect up a series resistance how-
ever, as the current flowing through the resi-
stance wire must be less than 10 mA in order
that the heating up of the resistance wire and
the gas to be measured may be neglected. Cer-
tain flight tests necessitate the use of an oscillo-
graph and in such cases it may also be of
interest to record the temperature of the exter-
nal air by means of this instrument. The
resistance wire of the temperature recorder is
then employed as one arm in a Wheatstone
bridge the out-of-balance current of which is
recorded by the oscillograph. The latter is fed
from a separate battery and in this case also
the current through the resistance wire should
be below 10 mA.
11
 12
Ap oved For Release 2006/12/19: CIA-RDP80-00926AO00800030024-6
--~W stilts
The Saab-2.9
Approved For Release 2006/12/19: CIA-RDP80-00926AOOOSnnn*In024-O
 Approved For Release 2006/12/19: CIA-RDP80-00 A000800030024-6
The Saab-29 is a single-seater jet fighter plane having a maximum speed calculated to
exceed 1,000 km/hr. The principle followed in its design has been to place all the equip-
ment such as the landing gear, the fuel tanks, armament, etc, in the fuselage, thus per-
mitting the wing to be constructed in the form of a rigid, smooth shell which is not
weakened by the presence of doors or the like. Notwithstanding the somewhat full shape
of the fuselage, it has been possible to keep the air resistance low. The air of combus-
tion is drawn in through a circular intake located in the nose and passes through a
straight, polished duct to a jet engine of the de Havilland "Ghost" type which develops
a thrust of approximately 2,200 kg. The adjustable stabiliser on the tail has been
placed high up on the fuselage to protect it from the outflowing gas jet. With this
arrangement the, discharge pipe can be shortened and the landing gear placed low down,
whilst the risk of damaging the tail on landing is eliminated. The wing which has a
pronounced sweep-back is fitted with automatic slots which improve the stalling properties
on landing and at low flying speeds. As in the Saab-21, the pilot's seat can be shot out
by an explosive in the event of a parachute jump, and the top of the pressurized cabin
can also be shot away by an explosive discharge. The wind tunnel tests have been of
an extraordinary far-reaching nature and have been supplemented by practical flight tests
to half-scale, for which purpose a Saab Safir has been fitted with a wing structure of the
same form as that of the Saab-29. The lower picture on the left shows this combination
and the other two pictures show rather clear the appearance of the Saab-29 with the
arrow-shaped and very thin wing, the high tail unit, and the thick fuselage. During the
extensive flight tests-the first of which is anticipated to take place in the autumn-we
hope to publish further articles in Saab Sonics describing our first "1,000-kilometre
plane" in greater detail.
13
 Ap[Rved For Release 2006/12/19: CIA-RDP86-00926AO00800030024-6
_kk% SONILS
A New Saab Invention
self-marking
target
towed by air; craft
A self-marking target has been invented by Saab which is primarily intended
for towing by aircraft. The originator of this idea is Mr. T o r s t e n
F a x e n who, in collaboration with Dr. Erik W i l k e n s o n, has pro-
duced a system of target marking which is likely to revolutionize shooting
practice both for fighter planes and anti-aircraft defence units.
The system of practice-shooting at a target
towed by an aircraft, which has been rendered
possible by Saab's invention, differs very appre-
ciably from earlier methods. Hitherto it was
necessary for the "towing sleeve" to be lowered
and for the fighter plane pilot to land before
he could ascertain his scoring results. By means
of the new invention, however, the result of
each shot can be communicated to him while
he is actually firing, an advantage which is
self-evident from the point of view of training.
At the same time the work of firing is facili-
tated and rendered more efficient, whilst a
saving in flying hours and fuel is effected.
The construction of the "Hit Indicator
BT-13 ", as the new invention is called, is illu-
strated in general outline in the accompanying
drawings. The operating principle is based on
the fact that the shock wave of the projectile
sets up radio signals through the medium of
a special microphone built into the target,
these signals being received by the marksman.
Thus the main portion of the installation is
the so-called "hit-transmitter" - a stream-lined
body enclosing the microphone. The influence
of the air stream, the dynamic pressure and
other disturbing effects caused by the towed
target has been eliminated' and it is the actual
sound impulse set up by the projectile as it
passes through the target zone which gives rise
to the signal in the microphone.
14
From the hit-transmitter, conductors pass
along the towing cable to a recording apparatus
in the towing plane. The records are either
read off by a person who informs the marks-
man verbally by radio of the result of his shots,
or the marksman may himself receive a radio
Dr. Erik Wilkenson
Approved For Release 2006/12/19: CIA-RDP8f)-OOG?FiAnnnRnnn`~nn74-R
 Approved For Release 2006/12/19: CIA-RDP80-00 6AO00800030024-6
AAB SWIS.
signal for each projectile which passes through
the target zone. The recording apparatus is
fitted with a counting mechanism for recording
the number of hits, and it is further provided
with a device for varying the size of the target
area. The zone within which hits can be indi-
cated may be varied between 0,5 and 8 meters
in radius according to the skill of the marks-
man and the calibre of the projectile, so that
the degree of difficulty can be adapted to the
stage of training attained.
In view of the fact that the invention is
primarily intended for use with targets towed
by airplanes, the weight of the equipment has
been kept as low as possible. Thus the record-
ing apparatus only weighs four kilos, the hit-
indicator two, and the batteries for generating
the current barely twentyfive kilos. The air-
borne parts occupy very little space and can
be conveniently mounted in the towing plane.
The new method permits the employment of
very much smaller targets, since no marking
of the bullet holes is necessary. On this account
the speed of the target plane may be increased
and practice can be carried out under more
realistic conditions.
A hit-indicating device of this kind may of
course also be employed for targets on land or
at sea, either stationary or towed. It thus pos-
sesses an all-round military value and in addi-
tion to this the employment of it means a con-
siderable saving of the time of training and
makes training more efficient, as the results of
the shooting can be read off immediately.
Furthermore, the practice-shooting with this
hit-indicator will be much more economic than
the present methods, which is still one reason
for the great interest in this new invention that
has been shown by the military authorities.
It is quite evident that the hit-indicator
BT-13 will be of a very great value for the
training of fighter pilots and anti-aircraft
defence personnel, and there is no doubt that
the adoption of this self-marking target will
give all military practice-shooting an extraordi-
narily increased efficiency.
115
 Ap vAed For Release 2006/12/19: CIA-RDP80-00926AO00800030024-6
5?NILS
The Scandia's
Engine Insta11ation
by
Aarne Lakoin'aa
The Scandia's engines are manufactured by
the wellknown American aeroplane engine firm,
Pratt & Whitney. The first Scandia model -
90A - is equipped with a Twin Wasp 2 SD 13
G R-2000 type of engine which has an output
of 1,450 BHP at take-off and a normal maximum
output of 1,200 BHP. Later models of the plane
- 90A-2 and 90B-2 (with pressurized cabin) -
will be equipped with much more powerful
engines of the Twin Wasp R-2180 type of
1,650 BHP at "dry take-off " or approximately
1,800 BHP with methanol- water injection.
Both types of engines are quite similar in their
design, and consequently the following descrip-
tion of the installation may be said to apply
generally to the Scandia's engine construction.
The engines are of the air-cooled, 14-cylinder
radial type with the cylinders located in two
rows. Each engine is fitted with a single-stage
compressor, injection carburettor and double
magnetos. Furthermore, a considerable part of
the auxiliary apparatus is mounted directly on
the engine, including starter, generator, fuel
pump, hydraulic pump, two special generators
for certain instruments and alternator for the
propeller control system.
The propellers are of the four-bladed Hamil-
ton Standard type with hydraulically operated
pitch control. The propeller blades can be
reversed to a negative angle of pitch, thus
producing a braking effect. In this way the
landing run may be shortened appreciably in
critical cases. The blades are protected against
icing by heating up the leading edges electri-
cally. The current required for this purpose
is taken from the airplane's common electrical
system by means of carbon :brushes on the pro-
16
peller hub. An electrical synchroscope is in-
stalled as an aid to the pilot in maintaining
synchronous operation of the engines.
The installation
The engine installation is of the so-called
"Power-egg" type, that is to say, the construc-
tion constitutes a single unit which can be
exchanged in a short time, whilst it may also
be employed as a right- or lefthand installa-
tion without necessitating extensive changes. All
that is necessary is to turn the exhaust mani-
fold so that the opening faces outwards towards
the outer wing, whereupon the noise of the
exhaust and any flames from the latter will not
disturb the passengers. In order to utilise the
exhaust jet thrust, the opening is constructed
in the form of a nozzle facing backwards in
which the exhaust gases are accelerated to a
suitable velocity. The energy contained in the
exhaust gases is here employed in the same
way as in the case of jet propulsion engines,
and th4 appreciably increases the net thrust.
Aooroved For Release 2006/12/19: CIA-RDP80-00926A000800030024-6
 Approved For Release 2006/12/19: CIA-RDP80-00 6A000800030024-6
5
AAB 5~NILS
Air intake
duct
high speed profile
Filter door
Air filter
Exhaust
outlet
Air intake Air intake
/br oil roo/er ror engine
In designing the engine mounting, special
importance ha-s been placed on the elimination
of vibration so far as this is possible, and with
this end in view the engine is suspended in a
tubular steel mounting fitted with eight vibra-
tion isolators. The mounting is fixed in its
turn to the fire-wall.
Air is supplied to the carburettor through
a duct which is so amply dimensioned that the
air flowing through it is kept at a low velocity,
L _ ~II
~ i p~ IP V'
d~ `4 il-b'
Air check II, t
robes Oil cooler rapt ~
installation showing the principal parts
thereby reducing losses due to friction and
bends. To prevent icing on this duct and also
on the carburettor, the induction air is pre-
heated in a preheating chamber in which the
air flows over the hot exhaust manifold and
undergoes a total temperature rise of 55-600 C.
The temperature of the induction air is regu-
lated by a door inserted in the duct, which is
operated electrically from the pilot's cabin. To
prevent sand and dust from penetrating into
the engine, the induction system is provided
with a filter system which is operated by means
of an electrically controlled door in the intake
duct. The filter system functions in such a
manner that coarse filtering first takes place
by inertia separation in which the heavier par-
ticles are removed from the induction air. Fine
filtration is then effected in the filter block
itself. By employing this double system the
cleaning of the air is carried out more effecti-
vely and the filter does not require cleaning at
such frequent intervals. It is true that the
filter system causes a certain pressure drop in
the induction air which reduces the engine
output, but this reduction of output is com-
pensated by the take-off margin of the engine.
Rain water constitutes a danger from the
point of view of icing at certain temperatures,
and for this reason water drops in the suction
air are separated out by a thresold in the intake
duct, and are led to a plenum chamber from
which they drain into the open air.
17
 Ap ved For Release 2006/12/19: CIA-RDP8
dAAB StHILS
In view of fire hazards the entire engine
installation is so designed that the possibility
of a fire spreading has been reduced to a mini-
mum. Thus, the engine with the exhaust
system is entirely separated from the accessory
compartment behind it by an engine diaphragm
of stainless steel plate. This highly resistant
material has likewise been employed for that
part of the engine cowling located at the back
of the exhaust outlet and cooling flaps, as well
as for the exhaust system which is of the con-
ventional form, consisting of the manifold and
common exhaust pipe. The accessory compart-
ment referred to above is separated in turn from
the engine nacelle by a fire-resistant fire-wall
which also consists of stainless steel plate. Fire-
resistant material has likewise been employed
for important details such as the oil tank and
induction system. Furthermore, the entire
installation is equipped with effective fire-
extinguishing apparatus and a fire alarm system.
The front portion of the engine cowling,
known as the cowlring, has been designed to
offer the minimum overall drag and the most
effective pumping of the cooling air. The nose
of the cowling is an annular NACA-high speed
profile (NACA 1-serie). For regulating the
quantity of the cooling air, cooling flaps are
provided which are located behind the engine
cowlring and are operated electrically from the
cockpit. After flowing through the engine, the
cooling air is led out, through the exit duct the
form of which is suitably designed from the
point of view of air flow by the provision of
shoulder baffles on the exhaust manifold. In
End view of the engine installation completely
assembled. Immediately to the left of the engine
nacelle the air intake for the wing anti-icing system
may be seen
Engine nacelle with the panels and the cooling flaps
opened
The engine cowling of the prototype (lefthand illustration) differs appreciably from that of the production airplane
1S
(righthand illustration)
Approved For Release 2006/12/19: CIA-RDP80-00926A000800030024-6
 Approved For Release 2006/12/19: CIA-RDP80-00 A000800030024-6
Valve construction for the carburettor air intake. The
above sketch on the right shows the path of the air
direct to the carburettor. In the upper lefthand illu-
stration this path has been closed and the air is warmed
up when it flows over the cylinders and through the
preheating chamber. Finally,- the lower illustration
shows the position of the valve when the air is forced
to flow through the air filter
designing the engine cowiring and the cowling
between the engine diaphragm and the fire-
wall special consideration has been given to
facilitating service- and inspection work as far
as possible. For this purpose the entire unit
consists of two panels only, which can be con-
veniently mounted and dismantled.
The oil system
is entirely included in the power plant, before
the fire-wall. The oil tank has an oil capacity
of 100 litres and is fitted with a circulation
cylinder (hopper) in which the air is removed
from the returned oil. The oil cooler, which
is of the standard air pipe type constructed of
light metal, is dimensioned to comply with the
conditions prevailing with a single-engine
climb at METO-power under + 40? C ambient
air temperature. The oil temperatures are regu-
lated by an electrically operated flap in the
outlet duct of the cooler. The operation is
thermostatically controlled and the temperature
of the inlet oil is automatically maintained
between + 60? and + 75? C, irrespective of
the external temperature.
The engine failure detector represents an
important feature from the point of view of
safety for the engine and the oil system. It is
installed in the oil sump of the engine, in which
the return oil collects. In the event of the
failure occurring in an engine bearing, frag-
ments of metal may be carried along by the
oil circulation. They collect in the oil sump
where they sink to the bottom and are drawn
to the detector, thereby establishing contact
between electrodes which transmit an impulse
to signal lamps on the instrument panel. The
pilot can then take the necessary measures
before greater damage is caused.
The fuel system
is mainly located in the outer wings and the
nacelles. There are two fuel tanks in each outer
wing immediately outside the connection to the
wing centre-section, with a total fuel capacity
amounting to about 2,900 litres. The fuel is
drawn into the engines by the engine fuel
pumps, or it is forced to them by means of a
pump installed in each tank. These tank
pumps constitute a stand-by and auxiliary
system which ensures the fuel supply to the
engines in critical cases. The fuel system is
designed in such a way that the fuel can be
transported from the left- to the right-wing
tanks and vice versa with the help of the tank
pumps. In conditions of emergency the fuel
can be rapidly jettisoned, thus permitting the
flying weight to be reduced by approximately
800 kg in 10 minutes. To reduce the fire
hazard, when draining the tanks, this process
Contd. on the third page of the cover
19
 Ap ved For Release 2006/12/19: CIA-RDP8
-00926A000800030024e6
AA% S?NILS
Technical Development Work
in the Saab Workshops
The continuous advances taking place nowadays in aeroplane designs make
heavy demands on the manufacturing processes employed. For the produc-
tion and assembly of the thousands of parts which go to form the finished
aircraft the workshops must have methods of manufacture at their disposal
which from the point of view of efficiency must be of the highest standard
obtainable. In this article Mr. A r e S v e n s s o n, chief of the tooling
department, describes the organisatilon of the technical development work
and gives some typical examples of ,the tasks this work involves.
Technical research work in the workshops
has an important mission to fulfil at the present
day in the rationalisation . of the engineering
industry. A distinction is usually made in this
connection between basic research and applied
research according to the nature of the work.
The essential purpose of the first category is
to investigate the general theoretical grounds
for the working and treatment of materials. The
latter form of research is concerned with the
application of the experience gained under ser-
vice conditions with a view to improving pro-
duction processes by means of technical deve-
lopment work of a practical nature.
From a Handicraft to a Heavy
Industry
The production of aeroplanes on industrial
lines is a form of manufacture of relatively
recent date. It. fell to the, lot of this industry
to develop manufacturing methods suitable for
series and mass production in the course of a
few years where the work had formerly been
carried on solely as a handicraft. In most cases,
moreover, this change had to be effected under
working conditions which, in view of the hurry
and bustle of the present age, were far from
ideal. In those days we were almost entirely
without experience of aeroplane construction
on a large scale. Furthermore, the expansion
occurred at a time when for known reasons the
exchange of experience with other countries
was practically at a standstill. The little infor-
mation that reached us through a much reduced
20
foreign technical press was for the greater part
of no value.
During the same period we developed our
first alhnetal aeroplane of the monocoque con-
struction type, a circumstance which further
complicated our manufacturing problems. Thus,
as in the case of so many other industries, we
were entirely dependent upon our own resour-
ces. Ani intensive program of experimental
and development work was now initiated with
the object of adapting the production plant to
the changed conditions. On the subsequent
removal of all restrictions we were gratified to
learn that in many instances we had achieved
the samep
abroad.
Mr.
Arne Svensson
Aagroved For Release 2006/12/19: CIA-RDP80-00926A000800030024-6
 . Approved For Release 2006/12/19: CIA-RDP80-00 A000800030024-6
AAB S
Development Work
The need for systematic development Work in
workshop practice is more manifest in aero-
plane production than in any other branch of
industry. Developments in the technique of
flight advance at an ever-increasing rate and
the demands made on the manufacturing depart-
ments by project engineers and designers are
in step with this progress. Manufacturing pro-
blems have to be solved even during the
project stage and designs must be carefully
scrutinized with respect to their possibilities for
series production. This continuous collabora-
tion in the work of planning and series pro-
duction is one of the essential conditions for
rational aeroplane production. It is being
observed more closely than ever now that we
are making the radical change from a propeller
propulsion to a jet propulsion in our military
aeroplanes.
It is not sufficient, however, for our designing
departments merely to keep themselves in-
formed as to working processes and resources
available in the workshops. The men in the
shops must look to the future, they must pro-
duce new plans and ideas, they must constantly
be prepared to adopt new means that will offer
a satisfactory solution of manufacturing pro-
blems. In this connection systematic develop-
ment work of a practical nature must be carried
on with the object of improving existing proces-
ses and trying out new methods and forms of
treatment.
This would place a heavy load on the
workshops engaged on series production. The
hands here are accustomed to working in
accordance with a familiar routine. Continuous
Fig. 1. Rubber pressing in a divided outer matrix with
an inner rubber stamp
experimenting with new methods would dislo-
cate this routine unduly and interfere with the
rythm of production.
We insist therefore, that any proposed
changes in a production process in use shall be
preceded by a thorough technical investigation
before they are adopted. This investigation
comprises preparatory tests and research work,
frequently in the form of detailed experiments,
from the course of which it is possible to form
an idea of the approximate results. If these
are of a positive nature a rough economic cal-
culation is made on the basis of the preliminary
tests, and if it is found favourable, the plan is
developed with a view to its application to
series production. Service tests are then made
under conditions approximating as closely as
possible to the actual working conditions. In
the event of these tests yielding satisfactory
results the new method is considered to be ripe
for introduction in the ordinary working chain.
It has been found desirable to concentrate
this development work as far as possible in a
department which is completely independent of
the actual series production workshops. The
step in this direction was taken some years ago
by the inauguration of a technical service
department.
Organisation of the Development
Work
Systematic technical development work of a
practical nature is carried on in the technical
service department in intimate collaboration
with the workshop- and designing departments.
The reports on investigations and tests which
are prepared in connection with each commis-
sion received are submitted to everyone in the
firm concerned. They are classified and filed
in the department together with index cards
and excerpts from. technical literature relating
to the subject in question, and constitute a
valuable fund of information on workshop
practice.
The value of this system is obvious. By the
cooperation of everyone concerned the infor-
mation on workshop matters of a technical
nature is available to the whole firm and does
not remain in the personal possession of indi-
vidual workshop employees as is otherwise so
frequently the case. Thus in times when fre-
quent changes in the staff are taking place,
effective provision is made for the continuity
of the work.
21
 Ap ved For Release 2006/12/19: CIA-RDP8 }-00926A000800030024=6
AA% SONILS
Fig. 2. Cold extrusion of light metal parts
The work of the technical service depart-
ment is mainly carried on along the following
lines.
Development of working methods
and tools. The purpose here is to increase
the general efficiency of the manufacturing
plant by the improvement of existing processes
and the development of new methods, tools and
machine equipment. The work includes the
designing, production and testing of tools and
auxiliary machines. It also entails amongst
other things the study of developments in
workshop practice with the help of technical
literature and the consideration of their suitabi-
lity for application to the manufacture of
aeroplanes.
An important feature in the development
work consists in the examination of new designs
insofar as they depart from the current prac-
tice from the manufacturing point of view, and
the indication of the most suitable methods for
their series production. For this purpose it is
frequently necessary to determine the suitabi-
,lity of the proposed method by trial produc-
tion to full scale.
The workshop equipment must also be supple-
mented in preparation for the proposed series
manufacture insofar as this may be necessary.
Working investigations. The object
of these is to ascertain the workability of metal-
and non-metallic aeroplane material by cutting
and forming, and also to determine the econo-
mic working requirements. The work includes
the testing of different tool material and the
shaping of tools with a view to establishing a
general tool standard for different forms of work.
Performance diagrams are then prepared
22
for the different materials, tools and working
data on the basis of the investigations. These
diagrams'' may be directly employed for cal-
culating machining times in synthetic piece-
work for example.
Techlnical advice and supervision
in special technical questions:
welding, heat treatment, surface
treatment. The working methods here in
question ,call for a technique which is of a totally
different character to that adopted for working
operations in which the condition of the material
does not ',change during the progress of the work.
In welding, for example, the material passes
through a whole series of metallurgical proces-
ses which the welder must learn to control
faultlessly. Careful supervision with respect
to expert work is therefore essential. Further-
more, a welded joint must be designed with due
regard to the possibilities from the point of view
of welding technique. The requirements are
more exacting in this respect than in the case
of a general design where the designer usually
has a greater freedom of choice without running
counter to any manufacturing problems.
Very exacting demands are also made of the
equipment for such working methods, in order
that it may satisfy the requirements covered by
the term "aircraft quality ".
It has' been considered advisable to entrust
such matters to specialists and include them in
the regular development work. In this way it
is possible to ensure treatment from every aspect
of problems arising, and obtain effective control
of the expert's work and a systematic supervi-
sion of the technical equipment of the work-
shops.
Plans and Ideas
of a more temporary character frequently alter-
nate with the systematic work of development
planned for the long view. We have even gone
to the length of employing individuals in the
workshops from time to time as "idea scouts"
whose sole task is to seek for possible im-
provements in the production system. In this
way we! have effectively sought means for
dealing with the specialist blindness from
which workers are liable to suffer when engaged
on extensive series production and routine work.
Many valuable suggestions for improved
working', methods have come from our own
workmen. We give our employees every encou-
ragement to participate actively in the develop-
Approved For Release 2006/12/19: CIA-RDP80-00926AO00800030024-6
 Approved For Release 2006/12/19: CIA-RDP80-00 A000800030024-6
Fig. 3. Form grinding with a precision-dressed grinding
wheel
ment work and for the past six years we have
been running a special organisation for probing
suggestions from the workshop staff. A mone-
tary award is made for every acceptable sug-
gestion.
The Technical Development Work
in the Workshops
has resulted in the course of years in a number
of greater and lesser improvements which have
been adopted to the benefit of the production.
A few examples of these are given herewith.
Rubber pressing is a method commonly
employed in the aeroplane industry for many
years past for the production of simple sheet
metal stampings. In principle it is a stamping
process in which the sheet material is pressed
between the shaping matrix on the one hand
and a resilient rubber die on the other.
The method has a very extensive range of appli-
cation, from the simplest flange bending opera-
tion to the heaviest stamping. Fig. 1 shows an
example of the remarkable possibilities rubber
pressing offers. The method has been developed
for threading sheet metal caps of the type
shown in the illustration. The material is
Fig. 4. Slide rule for determining economic cutting
speeds for turning
Fig. 5. Investigating the maximum permissible degree
of deformation when stretch-forming extrusions
placed in a divided outer matrix and pressing
is effected with the help of an inner rubber
stamp. The pressure applied amounts to several
hundred atmospheres and causes the sheet mate-
rial to fill out the contours of the outer matrix
entirely. This example is of interest inasmuch
as it demonstrates the use of rubber pressing
for the manufacture of typical mass-produced
articles.
The cold extrusion of soft metals is fre-
quently adopted in the production of sleeves
and covers. The tool consists of a drilled die
and a massive punch, and it is driven by a high
speed press. The amount of clearance between
the punch and the die is made equal to the
thickness of the material in the finished pro-
duct. The material consists of stampings which
are placed at the bottom of the die. Under
pressure, the material is caused to flow spon-
taneously and is thereby extruded into the inter-
mediate space between the punch and the die.
The cold extrusion method has been developed
further, and we are now also able to press hea-
vier parts and even unsymmetrical articles.
Fig. 2 illustrates two examples. In this work the
pressure attained is as high as 10.000 atmospheres
and makes the heaviest demands on the strength
of the tool and its suitable form.
The precision dressing of grinding wheels
with peristat rollers introduced in the U. S. A.
under the name of " crush dressing " has been
developed and adopted. We employ it both
for grinding tools and in production work.
Fig. 3 shows an example of aeroplane parts
which are ground to form along their whole
length by means of grinding wheels sharpened
23
 App ved For Release 2006/12/19: CIA-RDP8Q-00926A000800030024-6
~IAAB S 1 ltra
in this manner: The degree'of accuracy obtained
in the dimensions is very high and the life of
the grinding wheels and dressing rollers has
been found to be surprisingly good.
The method of improving the cutting proper-
ties and increasing the life of high speed steel
tools by sub-zero treatment has been tried out.
Particularly satisfactory results were obtained
in this connection with shears for cutting stain-
less steel plate.
Investigations concerning the workability of
aeroplane materials with cutting tools have very
naturally been concentrated on the high qua-
lity alloyed constructional steels. These materials
are available in hardnesses up to 450 Brinell
and consequently carbides have obviously occu-
pied a prominent position amongst the cutting
tools. Exhaustive tests for wear have been
carried out under workshop conditions. This
work has been done in parallel with the stan-
dardisation of materials, and up to the present,
working data have been tried out for turning,
planing, milling and drilling work. These are
each summarised in cutting speed nomograms
from which, with a knowledge of the cutting
data employed, the cutting speed for the mate-
rial in question and quality of cutting tool can
be conveniently read off. Nomograms of this
kind have also been prepared for cold- and
friction sawing and the machine shearing of
sheet metal. Fig. 4 shows how a cutting speed
nomograms has been transferred to a slide rule.
Carbides with negative rake angles to which
so much attention has been directed in recent
years have of course also been tried out on our
aeroplane steel which is so difficult to work.
Good results have been obtained in milling.
Thus, whilst the life of carbide milling cutters
has been quadrupled, the working capacity has
been multiplied six times in comparison with
the high speed tools formerly used. Extensive
tests have also been carried out with hard steel
drills. As the results of these it has been pos-
sible to (drill hardened armour plate and even
magnetic steel without difficulty.
The forming methods such as bending, draw-
ing, pressing and stamping entail an intimate
knowledge of the different materials' capacity
for forming. Investigations concerning the
bending radii and bending angles, drawing radii
and drawing conditions have been carried out.
in connection with the manufacture of sheet
metal parts. The riiinimum permissible bending
radius for tubes and extrusions has been deter-
mined by tests. The figures thus obtained have
been compiled in the form of rules and recom-
mendations for the designing-, tool- and manu-
facturing departments. Fig. 5 illustrates a test
for determining the maximum permissible
deformation when bending extrusions.
The technical development work offers a
variety of interesting tasks. It likewise allows
a good nsight into the various phases of the
production process. From those engaged in it,
however, it calls for skillful judgment free from
wishful thinking and premature optimism. Only
by the exercise of such qualities can the work
be carried on successfully.
Contd. from page 11
Tests carried out
The correction of a temperature recorder for
speed may be checked both by allowing the
recorder to have a certain speed in relation to
the stationary gas (the air) and by placing the
stationary recorder in a' current of gas the
velocity of which is known. With the first
method the absolute value of the temperature
correction is obtained whereby the previously
mentioned uncertain factors for determining
the theoretical correction curve are eliminated.
In the second case, on the other hand, only
the recorder's deviation from the adiabatic cor-
rection curve is shown but against this the
measuring devices required are not so compli-
cated. Measurements have been carried out by
Saab with a testing arrangement in accordance
with the first alternative partly with single-wall
24
" staudruck " thermometers and partly with
double-wall insulating temperature recorders of
the type shown in Figs. 1 and 2. Some repre-
sentative results of the measurements obtained
during these tests are indicated on the calcu-
lated adiabatic correction curve in Fig. 3. The.
testing arrangement (Fig. 4) consisted in prin-
ciple of a centrifugal arm at, the outer end of
which the temperature recorder was located.
The speed of rotation of the centrifugal arm
was controlled by means of a 50 HP motor.
Tests were also carried out with a temperature
recorder' so constructed that a vacuum was
produced at the point of measurement, whilst
at the same time the temperature was only
reduced by 20 to 30 % and became dependent
upon the height as described earlier.
Contd. on the third page of the cover
Approved For Release 2006/12/19: CIA-RDP80-00926A000800030024-6
 Approved For Release 2006/12/19: CIA-RDP80-00926AO00800030024-6
Contd. from page 24
In tests with a temperature recorder located
in the jet flowing from, a compressed air' con-
tainer (Fig. '5) the discharge nozzle was so
shaped that adiabatic expansion took place with
subsequent cooling of the gas. At the slow
down of the air in front of the recorder the
air will be reheated, and at an adiabatic pro-
gress it would obtain the same temperature as
the air in the container. The difference between
the temperature in the container and in the
recorder thereby indicates the deviation from
the adiabatic correction curve. This deviation
was found to be less than the measuring accu-
racy for speeds investigated up to 235 m/s, and
preliminary tests carried out with an expanding
nozzle for supersonic speeds have shown that
the correction curve applies here also without
any appreciable error. The values obtained
with the two above-mentioned testing arrange-
ments may be misleading however, if the recor-
der is not placed correctly during the actual
measurement. Thus for example, no heat
exchange must take place between the air to
be- measured and the surroundings prior to con-
tact with the recorder. The effect of the loca-
tion of the apparatus has not yet been studied
sufficiently but is now being investigated. A
recording equipment installed in an aircraft has
however, been calibrated at ground level where.
by both the ground temperature and the deflec-
tion of the recorder were measured at different
flying speeds. Values were then obtained
which, when corrected in accordance with the
adiabatic correction curve, showed a measuring
accuracy of -}- 1? C for the temperature of the
external air over the whole range of flight
investigated.
Contd. from page 19
is carried out through pipes which project from
the wing tips, that is to say, as far away from
the engines as possible. In critical situations
it must be possible to cut off the fuel supply
to the engines quickly. For this purpose the
fuel system, as well as the oil- and hydraulic
systems, are fitted with electrically controlled
shut-off-valves behind the fire-wall.
The demands with respect to safety have
received the greatest attention throughout the
engine installation. Means for preventing break-
downs in service are available to the widest
conceivable extent, and should faults neverthe-
less occur, they can be rapidly localised and
restricted thanks to the comprehensive safety
system.
U. D. C. 629.138.6 Saab Safir
KRABBE, A: Saab Safir - the gem of the air. Saab Sonics no.
3 1948 p. 2-3.
Design of the Safir was begun in 1944 and it made its first flight in 1945.
The plane is appreciated both by the Air Force and private owners. The
Safir has aroused interest both inside and outside Euro
e
In th
p
.
e course
of deliveries to Ethiopia a world record flight was made in 1947. South
America and Asia are promising markets.
U. D. C. 373.63
WIDENGREN, A: Technical education. Saab Sonics no. 3 1948
p. 4-7.
High quality production calls for skilled workmanship. Saab's -1 assembly trai-
ning school" forerunner of the technical training school. Task of the technical
training school. Foremen are recruited from the training school to some
extent. Duration of instruction and number of apprentices. Suitability test.
Trial engagement. Training contract. Practical instruction takes first place.
Theoretical instruction during three years. Number of hours of theory
Advantages. Hourly wage while training. Bonus and "reward for diligence
Leisure-time occupation. Sports- and social club.
U. 1). C. 536.5:551.524:629.13
SVENSSON, S: Temperature measurements from aircraft. Saab
Sonics no. 3 1948 p. 9-11.
Tests at high flying speeds necessitate accurate recording of the temperature
of the external air. Temperature recorders of small dimensions are required.
Principles. Temperature rise on slowing down a mass of gas. "Staudruck"-
principle. Temperature recorder developed by Saab. The adiabatic correc-
tion curve. Measuring equipment. A resistance wire is used as the measur-
ing element in Saab's recorder. The temperature is measured by means of
a crosscoil instrument. The temperature can be recorded by an oscillo-
graph. Testing. Thermometer centrifugal arm and air container. The
correction curve also applies to supersonic speeds. Values obtained when
flying.
U. D. C. 623.593.3:623.558:621.398
REPORT: A new Saab invention. Saab Sonics no. 3 1948 p. 14-15.
Brief description of the 'hit indicator for targets towed by aircraft, a Saab
invention.
U. D. C. 621.434:629.138.5 Saab Scandia
LAKOMAA, A: The Scandia's engine installation. Saab Sonics no.
3 1948 p. 16-19.
The engines are built by Pratt & Whitney and bear the type designations
Twin Wasp 2 SI) 13 GR-2000 and Twin Wasp R-2180. Much auxiliary appa-
ratus is mounted directly on the engine. Hydraulic propeller reversal.
Synchroscope for maintaining the same speed in both engines. Engine
installation of the "Power egg" type. The power of the recoil in the exhaust
gases is utilised. Double filtration of the carburettor's intake air. Compre-
hensive safety measures in the engine installation for the prevention of fire.
Engine cowling constructed with two panels to facilitate inspection. The oil
t
f
f
h
sys
em
orms part o
t
e engine installation. Oil temperature regulated by
thermostat. The engine fault detector records bearing faults. Fuel system
located in the outer wings and nacelles. Tank pumps as a stand-by and
auxiliary system., Rapid emptying through pipes in the ruing tips.
U. I). C. 621.7.001.6+621.9.001.6:629.13
SVENSSON, A: Technical -development work in the Saab work-
shops. Saab Sonics no. 3 1948 p. 20-24.
Technical research in the workshops of great importance in modern industry.
Basic research and applied research. Development work particularly desirable
in the aircraft industry. Manufacturing problems are solved as early as the
projecting stage. Development work is separated from manufacture and
concentrated in a technical service department. Development of working
methods and tools. Manufacturing investigations.. Technical advice on
special manufacturing problems. Employment of "idea scouts". Suggestions
from the workers are rewarded. Special applications of rubber pressing.
Cold die-casting. Tool- and production grinding. Sub-zero treatment of
high-speed steel tools. Diagrams of the different working operations are
prepared. Testing and bending of tubes and extrusions.
 Approved For R4lease 2006/12/19: CIA-RDP80-00926A000800030024 `'-
SVE 1 KA AERt N AKT,IEBOLAGET
AAB
A F T COMP N~~.~'_.
.ba
LI: ING ? SWE`DER ;_,