PUBLICATION OF SVENSKA AEROPLAN AKTIEBOLAGET (SAAB AIRCRAFT COMPANY) LINKOPING, SWEDEN

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00926A000500030025-8
• Release Decision: RIPPUB
• Original Classification: R
• Document Page Count: 30
• Document Creation Date: December 14, 2016
• Document Release Date: April 23, 2001
• Sequence Number: 25
• Publication Date: August 24, 1948
• Content Type: REPORT

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EVER. INFORMATION CONTM ED IN BODY OF THE FERN MAY DL UTILIZED
AS DEEMED NECESSARY BY TAE RECEIVING AGENCY.
SOURCE
publication of
Svenska Aeroplan Aktiebolaget
(Saab Aircraft Company)
Link3ping, Sweden
Documentary
DATE DISTR. 24 Au,t 1948
NO. OF PAGES
NO. OF ENCLS
LUSTED BELOW)
SUPPLEMENT TO
REPORT N
THIS IS UNEVALUATED INFORMATION FOR THE RESEARCH
USE OF TRAINED INTELLIGENCE ANALYSTS
1. The following En. liah language journal issued by Sven k_& .Ae Qglan. ctiabo1a~;et
(Saab itora ft.-Company) of Linkl-p3rg, Sweden is oi~file in the CIA library;
Saab Sonios
i er
January-March 1948
2. This journal contains pictures of some of the buildings of the Saab plant at
Linkoping, as well as pictures of management personnel and various aircraft
produced by the comparv. Among the articles are a brief introduction to Lhe
company illustrating its development and manufacturing progress, a techn Racal
review of Saab progress, a discussion of d few aspects on the design of
Saab Scandia Aircraft and an article by Erik :tilkenson entitled, "Flow Saab
Developed a New Bomb Sight".
EXPLOITED BY 13
RESTRICTED
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SVENSKA
AI ROPLAN AKTIEBOLAGET
SAAB AIRCRAFT COMPANY
LINKOPING, SWEDEN
Publisher: RAGNAR WAIIRGREN
Editor: OVE SCIIULZE
Immp'
Ragnar Wahrgren: Introduction.... I
Arne Krabbe: Saab Aircraft Compa-
ny 2
Bror Bjurstromer: A few aspects on
the design of Saab Scandia...... i
(:lies .l. Smith: The Scandia in the air ')
Report: Saab receives a distinguished
visitor ........................ II
IIis Nordquist: A technical review
of Saab progress ................ I1?
I rik Wilkenson: How Saab develop-
ed a new bomb sight ............ 17
Report: Non stop Stockholm Addis
Ababa ........................ 22
Corer picture: Travellers in front of the
Suab Scandia
(:111. i-lication summary for technical articles
is to be found on the third page of the corer
Printed in SNc(-dcu be Oscar Isacsons IS,I:Ircckcri .1e.
( Iet urg; 1918
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SM SONI[S is a journal issued by
Svenska Aeroplan Aktiebolaget (Saab
Aircraft Company), the Swedish aircraft
manufacturers. The journal, which was
inaugurated in 1945, has hitherto been
printed in Swedish only under the name of
" Vingpennor ". From now on an English
edition will also be published, the first
number of which we have pleasure in
presenting herewith.
The purpose of' "Saab Sonics" is to keep airminded people, both
in Sweden and abroad, informed of' our company's activities, develop-
ments and products. During the past years the name of Saab has
become well-known in many parts of the world, particularly owing to
our civil aircraft Saab Safir and Saab Scandia, which have flown
in many countries. It will be the aim of "Saab Sonics " to maintain
and strengthen these connections and to establish new contacts. We
shall make every endeavour to render the contents of the journal
instructive and interesting, and it is the ambition of the editors to justify
the confidence in the name o f'Saab that has been shown in every quarter.
We thus hope that the journal will fulfil its purpose in its new
form also and that it will be appreciated by all friends of Saab
throughout the world.
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Saab Aircraft
Company
Some of the buildings of the Saab plant at Linkoping
A brief introduction to the Company, illustrating its development and
manufacturing programme, by Arne Krabbe, Saab Public Relations Manager.
The, Swedish airplane concern, Saab Aircraft
Company, now can. look back on its ten-year
existence as a period of such great expansion
that the firm today represents one of Sweden's
leading industries. Its operation has constantly
increased, and now embraces the successful. pro-
duction of various types of aircraft.
The history of Sweden's aviation industry goes
back more than a decade, however. As early as
1911 airplanes were designed in Sweden. The
experience gained in the country at that time
has been utilized and further extended by Saab.
The tatters immediate predecessor was Svenska
Jarnvagsverksti derna at Linkoping, where an air-
craft division was established in 1930. This depart-
ment, ASJA, was merged with Saab in connec-
tion with the transference of the firm's head-
quarters from Troll.hattan in western Sweden to
Linkoping. Since that time Saab has operated
plants of approximately the same ground area
in these two cities, the operation running on
parallel lines in both. In the matter of orga-
nization, the administrative and designing depart-
ments have been located in Linkoping while
only such offices as are necessary for running
the factory are to be found at Trollhattan.
The economic development and constant
expansion illustrate Saab's increased importance
and productive capacity. On the establishment
of the firm in 1937 a new aircraft plant was built
at T'rollhattan. The capital at that time was 4
million kr. At the same time ASJ's airplane
factory at Linkoping was enlarged, so that the
two firms were practically of the same size at
the time of the merger in 1939, when the share
capital was increased to 13 million kr. The out-
break of the second World War impressed the
authorities with the necessity of further expand-
ing the domestic aviation industry. The Govern-
ment therefore initiated negotiations with Saab
for enlarging the plants and an agreement was
concluded, the capital being again increased, this
time to 21 million kr., which has been fully paid
up. The agreement related exclusively to an
increased production for the Air Force and did
not include any stipulation that the management
should be subjected to Government control. Saab
remained a private company operating exclusi-
vely on private capital.
Up to this time Swedish airplane manufactu-
rers had operated chiefly as licensees of foreign
aircraft producers, and Saab originally worked
on similar lines. From 1938, however, the Com-
pany began to design its own aircraft.
Present production is the result of experience
gained during the initial period, but we can still
regard our first original design, created in
1938, with pride--a single-engined bomber and
reconnaissance plane, the Saab-17. This plane
Saab's public rela-
tions manager, Mr.
Arne Krabbe
2
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A Few Aspects
on the Design
of Saab Scandia
The Scandia's chief designer, Mr. H r o r B j u r s t r ii ni e r, describes in
broad outline how the Saab Scandia was designed-Special articles which
deal in detail with the various units of construction of this plane will be
published in later issues of the Saab Sonics.
Up to the year 1944 Saab Aircraft Company
devoted its activities exclusively to the building
of military aircraft. In that year, however, it
was decided to take up the construction of civil
aircraft, and the plans for the Saab Scandia were
worked out.
This decision entailed very heavy investment of
capital for a Swedish industry and consequently
the costs for carrying out the project had to be
carefully estimated. For the same reason the
flying qualities of the airplane, its maximum
weight, performance, operating economy, etc.,
were calculated in the greatest detail during the
project stage.
'lhe preliminary planning occupied some con-
siderabletime, the idea being to build an air-
plane for which the requirements would be of
4
a nature entirely different to those called for in
a military plane.
We set out to build a twin-engined airplane
of the smallest size that could be expected to
find a market on the termination of the war when,
as could he foreseen, demands for air transport
would increase. Studies showed that good trans-
port economy could be achieved with a plane
seating 25 30 passengers. The plane should
primarily be suitable for European traffic, i e.
for distances up to 1,00(1 km. but should also be
economical in use over larger distances, where
the traffic density would not justify larger planes.
It will be easily understood that the longer the
distance, the larger will be the plane, which is
most suitable when considering the operation
economy. There is of course further condition
namely, that the demand for transportation must
be great enough to permit the plane to be ope-
rated profitably.
Fundamental requirements
The fundamental condition was that the plane
should possess a high degree of safety in flight.
as great, in fact, as technical knowledge could
achieve.
It is accepted as a general rule in aircraft design
that it is desirable to raise the wing loading,
firstly to increase the cruising speed, and second-
ly to obtain a reduced wing weight, i. e. greater
useful load (pay load). But an increase
in the wing loading not only raises the cruising
speed hill also the minimum flying speed (lan(!-
ing and stalling speed). For the Scandia, ho s-
ever, the minimum flying speed should not be
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7'hc rulnunish'tiliet, b,, ildin r;s 1h0- .tinnh pbutl of
7'rollhiileru,
liar gist n excellent sere ice fret' mounts %tar'. and
is still in ac live service io lie BoNal Swedish
Airfare' as well as employe for training pur-
poses by the Imperial l iltioli ii Air Force. Thu-
I0 Saab-17 machines were delrvered by the Swe-
dish Air Force to Ethiopia t-o Oct. 30, 1947.
( tur oexl design, Saab-18, it as once among the
world's fastest twin-engined 1?eernber planes. 't'his
plane has been produced in v,rious versions and,
similarly to the Saab-17. it I:.is been the objeel
of considerable attention abri'ad.
Complicated technical problems were solved
bN the first in connection will, the building of the
'~aab-2 I. This fighter plane nigh it pusher air-
screw marked it tuileslone :ii our production.
sand This was our first dr ign will, it nose
wheel ,,,at, it design which proved to possess
dentally the first plane of this type flew its first
tell flight as early as 1947 and we are expecting
mach from a jet plane type now being designed.
That is the general hackgrannd of Saab's acti-
vities. During the years that we were building
under licences and while we have been solving
various problems connected with war production,
the designing of civil craft has been maturing:
experience has been gathered and utilized to
In full extent on civil planes. The later success of
those planes is of coo rse a source of pleasure, hilt
is scarcely a cause for surprise, since it merely ful-
fils our expectations. A e are nevertheless proud
of our little three-seater, the Safir, which has won
it world record, and we are entitled to boast o1'
the performance achieved by Saab Scaudia our
1wur-engmed traffic plane for 2-1 32 passengers.
(fur products will be described iii more detail
in this and later issues of "Saab Sonics " and the
illustrations accompanying this article are there-
fore only intejrded to convey an idea of our
factory plants. Both in Linkiipiug and Trollha1-
lan they are fully up-to-date and corn pit re
favourably as far as size is concerned, with simi-
lar plants in other parts of the world. As T have
mentioned above, the two factories are of much
the saute size as far as construction above ground
is concerned. At I'inkiiping, however, we also
have an underground factors, an impressive
plant which will he the subject of all article in
the next issue of our publi(atiou.
such ad%inttages that it i- now lit obvious choice
Beginning in
1948, airplane production. will
for all new. types. 'l'est flights started in
1943.
be concentrated
at Linkoping while our latest
u.nd Igo Saab-2I salisfied all ranted that it
should he of the tricycle type. The nose wheel
gear will be somewhat heavi,~r than the tail
wheel gear. but increased safety and comfort in
lake-oil' and landing, and in to iing more than
eonulerhalances the sacrifice if weitr.ht. The
fact that all landing legs retract forward
may not he as easily recognized as an advantage
front the point of view of safetti In unforeseen
situations, however, the landiio-, gear must he
extended very rapidly, which becomes possible
when the gear falls out into the extended posi-
tion by its own weight and is drawn hack into
the locked position by the force & the air, which
amounts Ili about 1110 kg oil each leg. The force
of gravity and the air stream alas, offer the most
reliable emergency arrangement if the hydraulic
syslcm should fail to funclion s.ilisfacuorily.
I'hc longitudinal extension ? f the ffirselage
will depend upon the size of the wing surface
and the wheel base of the lauoding gear (the
distance hclween [fill centers of nose wheel and
71
The structural design of the wing
with three stars appears from this
picture
maiu wheels). The length of that fuselage Iuaving
been thin determined, it proved convenient to
place eight rows of seats lengthwise. A maximum
of' four seats could be arranged side by side, and
thus allowing it maximum number of R2 pas-
sengers to he carried (for short distances). For
longer travel. where the passengers comfort
required more space, three slightly wider seats
were placed in each row. providing seating space
for 21 passengers. Space should also be avail-
able in the fuselage for about 111 try` of cargo.
Crew space should preferably he eery ample and
allow room for four occupants. besides which
Ihere must he room for a lavatory, pantry and
cloakroom.
The engines should have an economic cruising
output of about 750 BHP and about twice as much
for take-off. We chose the American Pratt &
Whitney engine Twin Wasp R-2000 with a take-off
power of 1450 BHP. This is a 14 cylinder, air-
cooled, double-row radial engine. Later on.
however, the Scandia will also he equipped with
engines of the Twin Wasp R-2180 type, which
has it normal take-off power of 1650 RHP. By the
injection of a mixture of methanol and water the
lake-off power can momentarily be increased to
about 18011 BHP. We nave preference to the air-
cooled type of engine. because at present it can
he regarded as more reliable, lighter, easier to
install and maintain than a liquid-cooled engine.
The airscrews are (:amiss-steel with electrical
operation for constant speed and synchronizing.
They are wide blade airscrews to give greater
thrust at lake-off.
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The airplane was to be equipped with modern
instrumentation for flying and lauding. It was
also to have, radio receiving and transmitting
equipment, a direction finder and automatic
pilot. It should meet all demands for perfor-
mance, strength and other general requirements
according to the U. S. Civil Air Regulations,
which were chosen on account of the fact that
the modern international regulations which are
being worked out after the war are not yet
completed. The proposed ICAO Regulations
vary very little, however, from the Il. S. Regula-
tions now in force.
Final design
After the preliminary conditions had thins
been worked out, the details for the aircraft could
be designed. The work was started on the wing.
First we had to determine what system of design
would prove most advantageous, i. e. the number
of spars, and whether to use stringers or corru-
gated sheeting. 7'he result was the three-spar
wing which gave the most uniform stress distri-
bution both statically and with regard to fatigue.
Stringers and corrugated sheeting were approxi-
mately similar in value, but stringers were chosen
on account of the simpler production methods.
The wing is built up of three longitudinal spars
and transverse ribs. It consists of a center sec-
tion and outer wings connected by bolts imme-
diately outboard the engine nacelles. Short, bolted
wingtips complete the outer wings. The wing
spars have riveted flanges and the ribs are of
pressed sheet. The ribs are spaced about 350 mm
apart. Between spars the shell is reinforced by
stringers about 100 nim apart. There is a channel
for heated air in the leading edge of the wing
which has been reinforced in the direction of
flight. Time trailing edge carries wing flaps and
ailerons.
The ailerons are of a conventional Prise type.
and equipped with trim tabs. The wing flaps are
of the slotted type, which means that when the
flap is lowered, the link system for hearings is
such that the flaps simultaneously move back-
ward to form a slot between the wing and the
leading edge of the flap. This flap is simple in
construction and maintenance and gives the wing
it high maximum lift, which has been measured
in flight to about 2.5. The wing flaps are hydrau-
lically operated and have one cylinder each, but
they are also linked together mechanically.
The fuel tanks are installed in the outer wings
The nose wheel, the engine installation and
ih.e wide-blade airscrew on the prototype
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immediately oulboard the n.o'elles, and are
suspended in such a way that LI v are not affected
by the deforrnation of the wing,
!'ht- engine nacelles which rc riveted to the
acing ;ire huill np with fraul. , longerons and
coyer sheet. The nacelles onIV carry the en-lint-
installation, as the main latidinr gear is attached
directly to tlu' wing spars. 'I he shape of the
nacelles has been adopted to that of the engine
and the air inlet for the carburetor and oil cooler
which arc motanted under the engine.
The shape and structure of the tail are ron-
ventional, with fixed surfaces ,ntirely of metal
aril the control surfaces built sun metal frames
with a halarie covering. Apart front the usual
requirements for stability, the ize of the tail
has been determined by a nt6o-er of olher con-
ditions. In a nose-wheel airer,ift good control
of the plane along the transverse axis is essential.
so that, when the speed is eomisiderahly below
take-oft' speed. the nose wheel ran he lifted or
lowered easih, and consequeintly the control
forces most he moderate even when flit- eleva-
tors are filly applied. In view of this require-
ment the elevator balance war suhjeet to spe-
cial study in the wind tunnel. l'his applied also
its the rudder. i. e. the pilot nturl be able to keep
the plane on the course at take-of' speed with
Ime engine inoperative. 'T'hos -ii this case, too.
the control forces had to be moderate when
the rudder was fully applied.
The landing gear, wing flaps ;iud wheel brakes
arc hydraulically operated. Thy' working pres-
,ore of the hvdranlic ,,vsIvm is 'tl kg/cut= which
is produced liv a gear pnnap driven from each
engine,
Anti-icing protection is obtained by allowing
wan,, air to flow through the leading edges of
the wing_ Ihe stabilizer and the fin, the air being
heated in surface combustion heaters
The fire alarm system consists of s,,per-sensi-
tive indicators installed in the engim' and cargo
rooms. A nunnber of carhondioxid containers
leave been installed for fire extinguishing.
The first test flight
with the Scandia was made in the middle of
November, 1940. Since theta testing flight has
been continnYd according to schedule and the
rt-snlts have excelled expectations in every
rrspeel.
The economic cruising speed at an altitude of
.,)1011 in has been measured at 300 kni/hi which
is better than expected front the first estimates.
This will mean that with the H-218(1 engine the
economic cruising speed will be close to 4(10
kin/h.
.Maxirnont flying weight which is determined
h} the plane's rate of clinch on one engine will]
the landing gear extended is 14,1100 kg, which
is also better than expected front estimates. The
maximum take-off weight with R-2180 engine is
14.700 kg.
Fixing qualities which are ntuelr more difficult
to predict by calculations have proved to be
extrerileI good. Our efforts lo achieve good
stalling and single-engine characteristics in the
design hate surpassed o?ur most optimistic expec-
tations. The general verdict is that the Scandia
combines good performance with a high degree
of safety in flight.
The prototype Senadilt
ready" to Ioke off
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The Scandia in the Air
Captain (; I < e s J. S in i t It piloted the Scandia on its maiden flight and
during subsequent test flights. In the following article he describes the plane's
behateiour in its proper element.
It is very natural that the test pilots of an
aircraft factory have not had many opportuni-
ties during the period of more than seven years
that has elapsed since the outbreak of the second
World War to sit at the controls of it civilian air-
plane. The aviation. industry, in Sweden as
elsewhere, was called upon to strengthen the
nation's armed forces, and was therefore obliged
to specialize in the production of military planes.
It was quite it thrill therefore to settle in the
pilot's seat of the Saab Scandia and get the
"feel " of a cabin in which comfort was an impor-
tant feature in the design. In the military planes
this factor has always given way to demands for
a maximum of military efficiency. It was often
something of an acrobatic feat for the fur-clad
and parachute-equipped pilot to enter his mili-
tary plane on account of the numerous but neces-
sary service devices for firing, bomb release,
photography, etc. The absence of all such equip-
ment in the Scandia enhanced the lasting impres-
sion of unusual cleanness.
The practical arrangement and spaciousness of
the pilot's cabin are details which impress even
the veterans of traffic flying. One of ABA's
younger pilots expressed his feelings thus: " This
is something very different to the old UC 3 ,
words which made me recall the time when as
a night mail pilot, I exchanged the. barely covered
cockpit of the Dunker F13 for the comfortable
chair of the W 34; when the Ju 52 was consi-
dered to offer unheard of luxury; not to mention
the feeling of reverence with which I took my
place as second pilot in ABA's new I)C 3
Ornen ".
A. particularly pleasing feature in the Scandia's
cockpit- -apart from the logical arrangement
of instruments, the concentrated controls andthe
11 roominess" is the fact that the pilot has his
crew within easy distance. Any pilot appreciates
speaking directly to his wireless operator Rir
flight engineer instead of first having to call
them on the telephone. On the other hand,
the Scandia's telephone is a distinct asset for
contacting the air hostess instead of having to
ring for her as in the old method.
The first flight with the Scandia naturally
involved much less of a sensation at least
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for the crew-Ilian similar Ilights %% ill, the
Saab-18 or Saab-21. The latter in particular was
the somewhat. extreme result of io w and untested
designing principles. Aerodyn unists and other
experts experienced some difl'icculty in predicting
with any certainty bow it woul'i behave in the
air. The Scandia, however, although an advanced
product, was it development of` designs That had
already been tested. This, by the way, is prob-
ably Ilre only correct course to ,i,lopt in order to
adhere strictly to the air trailu's essential de-
mand for 100 per cent safety. Before i hr flight
the aerodynamists predicted that the elevator
would feel loose and that booking would be
heavy. The flight confirmed this ill full, loch
actually fostered greater conl silence Ili their
methods mid knowledge Than il' perfect results
had been achieved.
The first flight lasted for s.mie 20 minutes.
At the time of writing the plan, has been in the
air for about l60 hours. lit IPsv rhea itirne we
have been able to acquire a rood idea of its
qualities. I have been informed that the de-
signers made it it leading principle that. the
Scamlia should be as easy to handle_ at low
speeds as the now legendary W52. I believe
that everyone who has flown the Scandia, will
gladly testify that this aim ha- been achieved.
Anyone who has flown modern big military (or
even civilian] planes will derih e it thrill from
flying such as is possible with the ticandia at it
speed of t1O 115 kin/it while still maintaining
complete control of the plane Unless one has
flown it Saab Safir earlier, it is uii(ficult to believe
in sneli it possibility except Ili a helicopter.
haven with fully developed stalling, the qualities
are unusually good. Stalling occurs relatively
slowly and straight ahead with neutral rudder.
Stalling is preceded, as it. should he. by light
bid unmistakable vibrations front the rail surfa-
1 0
(:aptnitt Smith in the Scandia's pilot.
window
cc's. 'tuft observations have shown that the goad
stalling qualities are due to the fact, that stalling
begins at the roots of the wings while the air
flow at the tips is laminar to the last uromeul.
The fact that the plane can be controlled at all
at speeds as low as 11(1 115 kin/Ii may probably
g
be ascribed to the fact that the wing loadinhas
not been allowed to exceed a higher value than
is compensated by the improved wing section
and shape as compared, for instance, to the ju 52.
fn contrast to similar foreign airplane types in
which the wing loading often reaches the saute
values as in military planes of rather extreme
types, the- wing loading of the Scandia is not
more than 163 respectively 172 kg/m
These qualities in conjunction with it consi-
derable surplus output in take-olf, create it feel-
ing of safety to which great importance must be
attached. This is especially true when one calls
to mind Ilie great number of crashes which have
occurred in connection with take-offs.
Engine failure on it twat-engined airplane im-
plies it reduction by 50 per cent of available oul-
put in addition to increased resistance due to the
uttsy ininclric tensile forces. Single-engine flying
has therefore been subjected to particularly ex-
lsaustive. studies, and the Scandia has amply salis-
faed the high expectations in this respect also.
Willi one engine cut off and without feathering
its airscrcw, the airplane with only moderate
counterbanking can be kept on it straight course
with a slack rudder without any retrimming.
After the airscrcw has been feathered scarcely
any trim change at all is noticeable. It is dinibl-
fnl whether it is possible to make turns with more
than 00` inclination toward the feathered engine
as freely with many other similar airplane types.
4 untd. on page 21
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Saab Receives A
Distinguished
Visitor
Late last summer Saab was visited by Colonel
Douglas Bader- the well-known British fighter
pilot of the second World War. Colonel Bader
was in Sweden as the representative of Shell
aviation petrol service, and needless to say, lie
made the trip here by plane in a Proctor
flown by himself. his passengers were Mrs.
Thelma Bader, his wife, and Clarence Lejdstriim,
Director of Svenska Shell. When the Proctor
landed at Saab's field its original destination had
been Stockholm, but Col. Bader had heard so
much about the Safir from Saab, that lie wished
to test its superb qualities for himself in a test
flight.
And a test flight duly took place, with one of
Saab's test pilots-Lieut. Olow as " second
pilot" and Mrs. Bader as a passenger in the rear
seat. The young officer flew the Safir through
all its paces and his verdict during and after the
flight was very enthusiastic. He only regretted
that the present exchange situation rendered it
difficult to introduce the plane in England, where,
lie was sure, it would otherwise find it good
market.
Lieut. Olow has related an interesting episode
from the test flight. Iii braking after landing,
Colonel Bader experienced some difficulty with
the brake pedals. He has protheses for both
It is hardly noticeable that Colonel Bader has artificial
legs, when he jumps out of his Proctor plane on arrival
at Saab
Colonel Bader, nearest to the camera, in the
Safir together with Lieutenant Oloa
legs, and the position of the pedals is such that
his feet could not obtain a firm hold. In order
to brake, therefore, lie was obliged to hold his
legs on the pedals with his hands rather a
unique method of braking which was made pos-
sible owing to the Safir's nose wheel. A plan(-
conventionally equipped with a tail wheel would
certainly not have behaved as satisfactorily
without hand control.
Colonel Bader has a long and eventful career
behind him as a pilot. His experiences in the
air would provide abundant material for any
writer of thrillers. As early as 1931 he lost both
legs in an air accident, but undaunted, lie
carried on as a flier after his recovery. During
the war lie was a fighter pilot and soon achieved
fame as the result of numerous air victories. In
the summer of 1941 lie was shot down over Ger-
many and taken prisoner. In the crash landing
one of his protheses was destroyed; in apprecia-
tion of a brave opponent, however, the Germans
gave permission for a British plane to provide
a substitute limb by parachute.
Shortly afterwards Bader managed to escape.
He was recaptured, however, and spent the
remainder of the war in a prison cantp.
The fact that he is a cripple is scarcely notice-
able. He moves about freely and even dances and
participates in sports. Golf is his favourite sport
and during his visit to Sweden lie took the oppor-
tunity of playing on the Tylosand golf links in
preparation for the Danish Golf Championships.
The Colonel also enjoys playing tennis and
won a match at Bastad, which is an eloquent
testimonial to his agility.
From Saab, Colonel and Mrs. Bader flew on
to Stockholm, from which city they subsequently
returned to England.
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Saab Pro di
s?ab tia~ii
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tcts
The powerful nose section of the
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A k Technical
Review
of Saab Progress
by Major El is Nordquist.
Technical manager of Saab
Aircraft design and manufacture have advanced
so rapidly that today it is scar, sly out of pl'aee
to refer to " the good old fillies - when discussing
airplane production in tin earl, '30's. Nolwith-
Iauuling the steady progress male it m ight not
he amiss to glance hack, and w cord the events
of the past years before meauories fade into
oblivion.
I1'he design and production of aircraft were
begun at AS.I:A (All Svenska. Jiirnvagsverkstiider-
oa= (A5,1 I Airplane Departnieut ) at Linkiiping
about I930. 'i'bis concern's firm design, the Vi-
king, was a high-winged sport; plane seating
Mu'se' in an entirely enclosed cabin. The speed
w:r approximately I(ii kin/ h. Only Iwo units
of Ibis Ivpe were built, one of v, bich had a long
life and earned laurels as a rei,orter plane for
fit,- 5loekholnts-1'iclniugen- until, at a venerable
old age it landed with floats- nn a field and
was never repaired.
AI ahoul the same tints the R,oral Swedish Air
Force eommiraioned AS.)A to d, sign a training
plane, later known as the O " Of this type
AS] A built one land plane and another with
The Viking 1, the first all-Swedish design from .41t.
,Sverr.clr ,him nrhgsrerks(i vh run
14
float::. 11 would probably be very difficult to
fired an uglier or clumsier plane than this onc?
provod to he, but the blame should not be placed
entirely oft the designers, since the specification
they had to follow dial not allow flinch scope
for the introduction of clean lines and beast-,
in the design. There was no series production
of this type.
AS IA required work for their factory, how-
ever, but as it was quite clear that the market
would be very limited and that the costs for
design and development would never he covered,
Igo company declared its willingness to operale
under licences from foreign firms. As a result
of thas orders were received for the production
of 2Fa trainer planes of the Raab-Katzenstein-
Tiger chwalbe type. In the Royal Swedish Air
Force these planes were known its the SK 10.
Production was completed in the years 1932
1934.
In those -,ears acrobatic flying played an impor-
tant part in the training schedule: inter alia, the
inverted spin was very enthusiastically practised.
After it few fatal accidents the direct cause of
u hick was found to be that the pilots had not been
able to pull the SK 10 out of all inverted spin,
thorough investigations were undertaken in order
to discover the reason. I donht whether any other-
;nirplane in the. world has been put through so
many inverted spins as the 5K 10, and it is
-ontetlting of a miracle that Colonel Rengt Ja-
,ohsson of the Royal Swedish Air Force has not
nstair:ed permanent giddiness as the result of
ill Ill., inserted spins Willi varying centres of
_!r?avil-,, which he carried out for months on end.
To the hest of my recollection it was never
satisfactorily explained why the plane on certain
rare occasions could not he taken Dill of the
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inverted spin. In my opinion the result would
probably have been the same if any of the air-
planes of that, period had been tested to the
same extent. The flying qualities of the SK 10
were regarded as relatively good, however, and
the type was used in the Air Force for several
years, although it had a somewhat sinister repu-
tation as evidenced by the various nicknames
applied to it, such as "the Death Machine"
which, incidentally, was one of the milder
terms used.
In 1934 the first series production of military
planes was begun by ASJA. In that year a small
number of fighters was delivered to the Air
Force. They were of the Jaktfalken type
designed by the Svenska Acro in Stockholm, a
company which had been taken over by ASJA.
This plane had a Bristol Jupiter engine of about
500 IIP, a speed of about 300 km/h and great
manoeuvring flexibility. It ranked with the best
foreign contemporaries.
ASJA had not permanently abandoned its
plans for designing types of their own, however,
and in 1934 they completed the Viking II which
was sold to the Stockholms-Tidningen and given
the name of " Sefyr ". Often seen on foreign
aerodromes and familiar to everyone in Sweden
on account of its news and film flights for its
owners, the Stockholms-Tidningeti and the lead-
ing Swedish film company, Svensk Filmindustri,
it was certainly a subject for pride. Few priva-
tely-owned airplanes have probably had such a
long life as the Viking II notwithstanding all its
exacting assignments, sometimes on wheels, some-
times on skis and often on floats. It is a cause
for regret that a suitable market could not be
found for this type and that, therefore, only one
was built.
The Viking II had it Gipsy Six engine of 200
HP, a maximum speed of 235 km/h and could
take three passengers besides the pilot.
In the period 1935 1937 ASJA produced a
'l'lte fighter "Jakifalken ", Swedish built, here in . uru?e-
gian version
few aircraft of British design under licence of
the De Havilland Tiger Moth type. In the Air
Force this plane was known as Sk11A, it had it
130 Hl' Gipsy-Major engine and a top speed of
175 kni/h. It replaced the older Moth Sk9 as
a training plane and certainly gave long and
faithful service. The type is still in use in many
places in Sweden for towing anti-aircraft targets
or gliders.
As early as 1933 the Swedish Royal Air Force
had acquired a licence for building the famous
British airplane Hawker Hart. The Air Force
devoted much time to the translation of drawings
and slight modifications of the design, but even-
tually ASJA received an order for twelve planes
of this type, which was later increased by another
six. This was considered a very substantial order
at that time.
The Hawker Hart, a two-seater, having a
Bristol-Jupiter engine, was used as a dive bomber
and to some extent as a reconnaissance plane.
When it first made its appearance in Great Bri-
tain it was regarded as a miraculous production,
and undoubtedly it was a fine plant. Its speed
was greater than that of any of the fighter planes
then in service in Great Britain. Unfortunately,
however, it had already become somewhat out-
of-date by the time it was taken up by the Royal
Swedish Air Force. This points, clearly to the
necessity of designing machines within the coun-
try if it is desired to keep ones material up-
to-date.
The B 4, as the Hawker Hart was called in
the Air Force, was equipped with a Swedish-built
Bristol/Nohab My VII engine of 580 HP giving
it top speed of 270 km/h.
Front 1936, when an expansion of the Air
Force was decided upon, the outlook for the
Swedish aviation industry to work independently
of foreign design improved considerably. The Air
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-- wi Saws
Force at thal time set the Aw,JA a hard task
wltcu, as a condition for placitt~r all order with
the firm for 20 locke-Wulf Sti,?,_,litz', it was sli-
pulated that delivery ntust be r-Frmpleted in the
same time as that within wlri,, h the machines
could he obtained from the original licensors.
'I'll(- ASIA received drawings i nl part of the
tool equipment late in January. 1938, and began
delivery in August the same year. And this was
done in spite of the fact that t1w delivery of the
instruments which were to be mounted in the
planes was nearly it month late' The plane was
equipped with it Siemens Shl4 engine giving it.
top speed of 175 km/h, and it is still serving
as it training plane.
It was not. considered suffici, of for the pilots
tnerely to learn Ibe elements of flying. however.
'I'hcy also had to master the coetrol of the heavy
planes which the Air Force wars purclutsitig lit
increasing quantilics. Art intermediate type was
found necessary and in 193,;, the Air Force
acquired the right to build the kmcriearr " Nortlr
American NA 10-4" which in S eden was known
as the Sk14A. Lt this plane i new, structural
method was introduced, the wings of the plane
being made in stressed skin crrnstruclioar which
is now common praclice. The -4k14A, having an
unusually powerful engine for it training plane
t tire 445 Ill' Wright Whirlwind) and therefore
it cuntparatiivcly high -peed 2711 koi,10 wits
excellently fitted for its task. Itremained on
Ilie production programme lot six years.
The Aircraft I)epartment I the ASi gra-
dually required more and nrisre space and its
separation from the rest of the firth was deemed
desirable. '.flue history of Ihi- separation does
nol fall within the scope of [Ili- arliclc however.
In 1936. which, as explaineef above, urarkNI a
turn in the history of the Bt-val Swedish Air
Force, it was decided to stablisll a fleet
of heavy bombers. The Air Force chose the
German twin-engiued bomber. Junkers In 36K,
which in Sweden was known a- the 133. l'roduc-
lion in Sweden of this type wa? considered desir-
able and was start(-(] in 1938 at -~aah's newly-built.
factory at Trolllratttut. The pLmue was considered
fully up-tit-date with a speed of 375 kin It from its
Ilristol/SFA My XXIV etrgin+, of 931) 11P. It
was faster Ihan the fighters in .ervice in tiwcden
at the time. The 13 3 which i, still sent in the
air occasionally was it siressed skin design and
front then on this has been t.Yre dominant type
of construction at Saab.
Saab also contributed to ti increase in the
The first. of Saab's own de-sigrrs the dire bombing and
reconnaissance ai.rcruft Snob-1;
uutuber of light honthers by building the Atne-
rican Northrop 8A-I for the Air Force. This
plane, known as the 135 within the Air Force,
was far more streatoliued [it design than airy
Irrecetlinr types and in its general uulline was
it very beautiful plane. It was fitted with line
saint' engine as the B3, the speed being about
330 kill It.
It will be realised that in tine pre-war years
efforts bolo at ASIA and at Saab were chiefly
devilled to production under license. The idea
of producing from their own designs was always
kept in mind, however, and as the international
situation became more and more complicated it
was clear to leading Swedish aviation circles that
Sweden would not be in a position to maintain
it modern air force based on foreign designs.
lit recognition of Ibis fact Saab set, to work
on its first original design which, according to the
specifications received from the Air Force, was to
be it reconnaissance plane. II was later decided
that ihtr plane should also be produced in the
form of a bomber. in 1941 it sensation was
caused- for it cannot be denied that it wa-
it sensation when news was first published con-
cerning the Saab-17, or 1317 and S17 as it was cal-
led in the bomb._r and the reconnaissance typee,
respectively. This plane is fitted with three dif-
ferent is pes of engines: the Pratt & Whitney/SFA
X
'I'X(:-3 0l' 1,050 lIP, the Bristol /S FA MY Wk
of 980 III', and the I'iaggio 1' Xl 11C40his of
1,050 HI'.
Vt lien reports of 1lie Saab-17 were priblis}tecl
the design of the next airplane was already far
Contd. on the third page of the cover
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OQ0025-8
How Saab Developed
A New Uouib Sight
During the second World War Saab not only produced bombers but also
increased their fighting efficiency by equipping them with a precision bomb
sight of an original design, based on a new bombing method. The author of
this article, Dr. E r i k W i l k e n. s o n, brought forward the fundamental ideas
of this new bombing technique in 1940, and was then responsible for the design,
development, and manufacturing of the new bomb sight. The theoretical
problems of dive bombing have earlier been examined by the author under
the title " Dive Bombing", which treatise was accepted 1947 as the first
doctors theses on an aeronautical subject at the Technical University of Stock-
holm. The story told here is therefore devoted to some historical and
engineering rieu?s on the subject.
There is a general desire in air bombing to
achieve the greatest possible precision in bomb-
ing without exposing the bombers to too great
risks from the active air defence, fighter planes
and anti-aircraft artillery. In regard to the mili-
tary conditions, however, the problem varies, in
accordance with the size of the country, its mili-
tary position and national policy. A great
power often primarily needs heavy bombers with
a wide operational radius in order to attack
distant targets. Such bombers arc forced to
release their lethal loads from high altitudes in
order to get beyond the reach of the anti-aircraft
defence, but in so doing their bombing accuracy
is reduced. All efforts to increase accuracy
result in very complicated instruments and auto-
matic pilots.
For a small country such as Sweden the aim
is quite different. Thus the Swedish Comman-
der-in-Chief, General Jung, in his proposals for
the defence, of March, 1947, points out that the
activity of the air forces apart from fighter de-
fence should comprise "attacks against an invad-
ing enemy and his advance bases." It is obvious
that comparatively small medium bombers are
suitable for such tasks. By using smaller air-
planes it will also be possible to maintain a
greater number on the limited appropriations
alotted for this purpose. Regard must also be
paid to certain special factors; the potential inva-
der will probably have mastery of the skies, and
the direct military objects as mentioned above
will often be small (and mobile) and therefore
difficult to hit. But smaller bombers are more
easily manoeuvred than the heavy long distance
bombers, and this gives them some chance of
escaping the ground defence without forcing
them to high altitudes for bombing.
Dive bombing
The points of view set forth above indicate
that in Sweden there have been special reasons
to study precision bombing from aircraft operated
on mobile tactical lines. In point of fact the
Swedes have been pioneers in dive bombing
since 1932. The procedure then worked out was
the following: The pilot, who is also the bomb
releaser, heads for his target in an almost verti-
cal dive from an altitude of about two thousand
meters, releases his bombs from an altitude of
600 to 1,000 meters, and then pulls out of the
(live, sometimes quite abruptly because of the
proximity to the ground. The bombs continue
towards the target on a very straight course.
A high degree of accuracy can be obtained with
relatively simple sights, on account of the fact
that the variations in the so-called release factors
(dive angle, release altitude, release speed,
etc.) do not play a very important part. On the
other hand dive bombing makes great demands
on the pilot's skill, especially when manoeuvering
into the correct position for diving.
New bombing method
As planes became more rapid and heavier, dive
bombing was rendered more difficult. The uca-
rest approach to solving the problem was found
to lie in the reduction of the diving speed by
dive brakes. But these did not eliminate other
disadvantages and thus the idea originated to try
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an entiref k 41iffCretrt honrbi tg methorl, t1ierehN
facilitating; the task of the pilot and making
honihiug more effective from the ruilitars point
of vii?%.
\N Iwo diving ill nieditnn sleep angles- the air-
plane does not increase its spr .?d so rapidly (even
without brakes) and the neeal for altitude ahoy
the target is appreciahh redur?ed. Thin the pilot
Call perforut a dive in it 40 angle much more
easily limit in an 80' angle, but there are diffi-
inllies of another kind. Th? rurvaluri of the
lmiidi path increases conisi(L raf)ly and the in-
fluence on it of the dive allele, the release alti-
lude and the release speed become more critical.
l veo at it short disguise from the target the
(mr?valitre will he so great I'rrat the pilot of it
cooventi(n:.rl single-engined I omber is frequently
enable to see the target at the moment of bomb
release. lit an airplane the visual range is
Iinriled from -) to 1(1? downy, ,ird in the foirwaril
dircelion while the target live may have to lie
III or even Ii" do%nwar(I at the release at
a safe dislanec from :mill air( raft fire,
hr order to facilitate bonibbing in shallow or
nredirrnr dive angles it was sherefore? suggested
al Saab early ill 1940 that tiomhing shoulld be
(fl'ecled in the following nrrnner: the pilot dives
ill a nmderale angle straight Vir the target, sight-
ing wilh the same fixed sight that he uses for
the fort+ard firing weapons. After reaching it
suitable release position, lie presses the bomb
release button and takes his plane nut of the
dive by a pall-out. The bomdis should thin he
released when the plane passe- the angle which
ixaitly Compensates the curvature of the bomb
path. Obviously this position must he deter-
mined amtiunati(ally bk an nsirumenit tn,hich
Constantly measures flying altitude, flying speed.
(live angle, etc., and front then, factors computes
the correct position of relea for hitting the
target. We have since learned that the German
air force used a bombing method daring pull-
ma, in it similar manner but with unsatisfactory
technical arrangements and in-trumenls. so that
the demands for suitable tar tics and accuracy
were. not fulfilled.
1 detailed discussion of the proposed method
showed thal it would he worth making great
efforts In realize the proposa . The task was
therefore to sillily carefully 1hw possihililies of
roust rucling the instrument ii i essarv for auto-
matic precision bombing dtiriir,r pull-nut. First
the bit listic problems were tallied so that a
e:tlctilalion of errors could he it tdc. This implies,
that the rc(prired accuracy of instruments and
mechanisms could he estimated so that target
misses should not be too frequent. It was found
that demands on the measuring insirmnerris
would have to he much greater Ihan could be met
by existing insirumeuts. For instance, the dive
angle must be measured by it gyroscope with
only a fraction of the marginal error of existi11g
instruments. The altimeter and the speedome-
ter sbomlc give correct data with much greater
exactitude than standard instruments, even in
the dive, where altitude and speed vary rapidly.
In studs mug the detail problems therefore, it was
deemed difficull, hilt not absolutely impossible.
to overcome the obstacles in some way or other.
Even at that early stage mneh interest was
displayed in Saab's proposal bk the experts of
the Hov:rl Swedish Air Force.
Projecting
In till spring of 1940, the author was commis-
sioned by the Saab management to devote his
whole time to the project for the purpose of
first developing a trial instruneut. As a colla-
borator I got Mr. Torsten Faxen, who for several
years was directly responsible for a great part of
the work in which his training as both a dive
bomber and a graduated engineer was invalu-
abb
The first task was to find possible practical
solution, of the difficult detail problems. Spe-
cialists in instrumental technics who were cori-
sulted considered that our demands for accuraiv
were too high tinder t:he circumstances. There-
fore we had to approach the problems along
entirely new lines. The sitturtimi in fact required
a number of minor in entimts. in this article
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an account is given of the ruauner in which a
part of the task was solved.
The usual method of measuring the altitude
of airplanes is to measure the static air pressure
around the airplane with some form of mano-
meter. A certain air pressure indicates quite,
different altitudes when the air is cold and when
it is warm, however. There may be. deviations of
-1- 10 %, which is far greater than we could
accept. Speed measurement from airplanes is
usually done by measuring the dynamic pressure
of the air speed against a tube projecting for-
wards, the Picot-static tube. In this case
both the temperature and the static pressure
of the air are essential factors, so that denser air
gives higher pressure than thinner air at the same
flying speed. One way of solving Ihe problem
would naturally be to measure air temperature
and correct the indications of the altimeter and
then correct the speedometer with allowance for
temperature and pressure of the air. Actually
such instruments have been designed, but they
must necessarily be rather complicated. We found
at the time, however, firstly, Ilia] the ballistic
equations could all be converted so that altitude
and speed were combined in a certain manner,
and secondly, that the same combination could
easily be calculated from the individual measu-
rements of the static and dynamic air pressures
alone. In this way we had found a simple
guiding principle. It remained to achieve the
desired accuracy of the measuring instruments
themselves.
G
7/ =7T7 i/ 7it
The special bombing method tvith
release in the pull-out. A. The pant,
of the plane in the pull-out. H. Booth
trajectory. C. Point of aiming. U.
Point of release. E. Target. F. Aiaring
line. G. Direction of departure. rp
Dive angle. 6 Angle of divergence
We had great respect for the gyroscope
problems. It was generally considered that flu,
design and construction of good gyroscopes
requires long experience. Our task made it
necessary, however, to produce gyroscopes wills
many times greater accuracy than Ihal of the
corresponding airplane instruments. In this
case too, the problem was studied exhaustively
and by it few fundamental inventions we actually
succeeded in realizing essential improvements in
accuracy without detriment to the practical func-
tioning of the gyroscopes.
Experiments
A period of experimenting began in the sum-
mer 1940, with the definite object of building
a trial model of the bombing instrument. In a
small laboratory which had been equipped for
the purpose, we studied the possibilities of
carrying out the various suggestions for the solu-
tion of the technical detail problems, and under
Mr. Faxon the designing of the trial instru-
ment began.
Many difficulties were encountered. The rapid
changes of altitude and speed in the dive made
great demands on the immediate reaction of the
instrument. Various causes for time delays were
therefore carefully studied, but only after pro-
ducing a few interesting inventions of details did
we obtain the basic conditions for achieni1cg
accuracy in spite of temperature changes. vibra-
tions and external acceleration.
After a number of tests and improvements the
prototype was ready. Laboratory experimenlr
showed that this apparatus could measure the
desired quantities with great accuracy and make
computations of the formulae which had been
deduced from the fundamental ideas. The labo-
ratory experiments were arranged as nearly as
possible in accordance with the desired func-
tioning in the air. Thus the instrument was
placed in an experimental jig, representing an
airplane. By means of a hand lever this jig
could be manoeuvered for " diving " and " pull-
out " and there were also racks for suspending
bombs, bomb selectors and such articles in the
equipment, everything corresponding to the
actual equipment of an airplane. The ground
tests could therefore be carried out in a realistic
observable manner, and denionstralions
and
arranged for the Royal Swedish Air Force
strengthened the confidence in the new tnethod.
An airplane was put at our disposal and flight
tests of the new instrument were started.
is)
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h rung the outset the air testa proved that the
farnel:nnental idea was correct, oantely, that the
pilot could arcuralely and easils dirr'ct his air-
plane Towards the large) in rnediarnt steep
dive and dial the poll-out from she diye could he
ntadv in Ittc calculated luau) .'r_ I ntil these
preliminary tests had hrv?n ueade, it was of,
('ours' impossible it) tlclerniirw whether this
bombing method would be I.'avliealele. 'Flie
frnrclionin, ref the trial instomenl was first
checked by electric treasuring devices and lannps
which registered the bomb rent,(' during pull-
out. AK hen the results aplerare,, favourable, the
first releases of practice booths ('ere begun. 'hhe
result showed well contenlraled hits, which pro-
ruised well for the future.
Tests were continued for nral.ev month with
nuneroIIS diffirullies hut also Aaith many Eur-
cesses. If may he nrenliooed iii short, That the
allinu?Iers and speedometers wee actually found
to give the desired high degret of atcuravv of
nreasnrement in the dive and Iliat the nt'asure-
tuenl of the olive angle proveel to satisfy our
demands on the gyroscope. k,,.perience called
for InnIV ahi?ralions in details bill the initial
principles for the rneasoring oslrnmenl,: and
design proved to he correct.
'I'hr first Trial instrument was 'tot entirely aulo-
truuic. It carried out measure_ni+?nts and valen-
falion- aallmiaticalIv during (Iive and bomb
release 11111 it flail to he served by a elan he-
tweed releases. It remained io devole oon-
>,iderahle 'p'orts to the further leveloprnent of
the ills[ rrrmertt nrtlil completely. urlomatie fnne-
Iioniug was obtained and Io de,.iI,rrr it in detail
so that maxinntm reliability rordd be achieved..
We drtfled a design for such an instrnrncnt and
uggvslcd it) the Air Force thkt it should he
ordered for the Swedish light hornhers. The
"uggcsiion was earefulIv studied uul adopted.
Serial manufacture
'T'he little group of engineers wleo had hitherto
taken part in the work were wuv set a moire
difficult task. Firstly, the numb-r- in Ihr ~!rouip
had to be increased, that is. ratan, hegimrnrs had
to he taught, and serondly. W, had to design
it-liable insrI'll rnrnts for serial f~roduelioo. At
that, lime Sweden's instrunn-nt ittdtlslrv was
deloged wills orders from the awned fours for
the produclioll of .melt precision parts as had
,earlier hee?n procured from al)I ad. Al laah
Itractirally lit) experience had f'eu gainrd ill
instrument design and niarurfaeitrre; we there-
fore had to start by establishing a standard for
designs. tools and machines. ht six months the
designing group was increased sixfold and the
work was in frill swing. An inslrurnonl work-
'hop was .laded, production hegaur, orders were
placed with other industries and as early as the
surnrner of 1941 the first instrmnerri of a series
production hype cotr1d he tested in the air.
Air teas with series model inst.rumenls
were carried oil energetically along with thorough
lahoratorv tests in severe cold, under vibration
Mill of long-time use. The rneehanistns fre-
queniIv gave trouble and fm? a long lime we made
about 100 detail changes a month. We did not
t"ncounter anv essential difficnllies. however, and
preparations for large scale deliveries proceeded.
During Tests w itli these model instrurnents
it. was repeatedly confirmed that this method of
bombing fulfilled the hopes we had made of it.
It became clear that the pilots ynirkly learned
Ilse procedure, that the sighting method gave a
clear view of the target, that release could be
effected at the desired long distance and that
accuracy was nevertheless very good. i';very-
one therefore was interested in having the irtstru-
rnent ready for practical service as soon as
possible.
After quantity production deliveries had heeu
is progress for some tine, nnexpecled difficud-
ties suddenly arose. In 1913 it became clear that
the series-ntaunrfactured instrtnnenl were not as
reliable as we had expected after the preceding
tests. We at that time, encountered a serous
=horteoming in the gyroscopes. 'T'he rotor which
ran at a speed of 13,000 r. p. in. had to ran vasilr
tin the hearings to function satisfactorily ill cold
weather. but it was now found that the hearings
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slid not stand [It(,, strain for as long as we had
hoped. Certain other Swedish gyro instruments
proved to have the same shortcoming. our fears
that long experience was necessary for the con-
struction of gyroscopes that are reliable in every
respect and that such experience did not exist
in Sweden seem to have been confirmed. After
consulting all Swedish experts on the subject,
however, Mr. B. Sylvan and E. Wallin, of Saab
made an important laboratory discovery, which
permitted all phases in the process of deteriora-
tion in the beardngs to be investigated, and the
two specialists very soon found an effective
remedy.
Other shortcomings which reduced the relia-
bility of the instruments in practical use were
also studied and remedied, but the account of
the gyroscope difficulties will suffice as an
example of our designers' exceptional perfor-
mance. Consequently we were soon able to intro-
duce such changes that the complicated instru-
ments with their 2,300 parts have always func-
tioned perfectly ever since.
Economic factors
Another part in the develolpnenl should be
mentioned briefly, the economic side. The bomb
sight is a complicated instrument and is there-
fore comparatively expensive. 'I'.he price can
even he estimated as several per cent of the
airplane cost, but the expense has proved to be
entirely justified by the increased value as it
fighting unit which a light bomber gains by the
use of this instrument. The very method of
bombing which is made possible by the instru-
ment reduces the risk from anti-aircraft fire dur-
ing attack and so increases the lifetime of a
bomber in war. The high degree of accuracy
may be said to make one airplane so equipped
to take the place of several machines and its
economic value ruay be reckoned accordingly.
1!:ven in peacetime savings are apparent : the
training period can be shortened or devoted to
other important tasks, since bombing has been
simplified. Another valuable quality, especially
in peacetime, is the fact that the moderate dive
angle makes for increased safety as compared
with (live bombing in almost vertical dives.
When it became it question of carrying out this
radical proposal for bombing, Saab's willingness
to take risks was of the utmost importance. .11
was not merely a question of developing it single
trial device by experiment but of initiating an
entire. department and placing considerable
orders with many suppliers, before the dctivetries
could start and an economic result be attained.
Saab Iran put many millions of kronor into the
project up to the critical year 1943, when tech-
nical difficulties accumulated and placed a hea%v
responsibility on its as the designers.
indirectly, Saab's work on the precision parts
in the dive bomb sights have resulted in the
establishcncnt of a new department at Saab for
the design and production of intricate rn -ebani-
cal devices, based on Swedish standards and
suitable for the special demands made of such
important material in the air. Our presrul
apparatus department under the managerucnt of
Mr. Fax(-n has expanded from the work with the
bomb sights and today it handles lnnulreds oi
innportaut devices on our airplanes.
In conclusion
one might perhaps venture to say that the new
dive bomb sight has made possible it highlN
advanced bombing technique for Swedish aero-
strategie conditions and that Saab contributed
in this respect to heighten Swedish military
strength during the latter half of the war.
Contd. from page 10
Intentional single engine stoppages after take-off
with it maximum effect have proved that in these,
circumstances the airplane can be kept on a
straight course at speeds as low as about 150
km/h, which allows it wide margin of safety, as
the most suitable climbing speed is something
like 225 km/h.
But can an absolutely new airplane be per-
feet, one might ask? Must there not be some need
for improvement? There certainly are a number
of details on the Scandia which are not ideal.
Tine pilot's bad weather screens are not suitable.
The rudder harmony is not quite satisfactory, as
stated above. 'l'ine pilot's seat might be more coni-
fortable. But these are all matters which can
and will be improved. When Saab's test pilots
finally hand over the Scandia for mass pro-
duction it will not only be a good airplane, it
will be the best of its class, and the fact that it
will be the best is largely dependent upon our
effort; the Scandia itself possesses the prerequi-
site qualities.
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App ;k
Nun-stop: Stociholm
/i dais Ababa
(lni((ue A viation Per f ormance with a Saab Sa f i.r
In f1lev, 1947. the Su roc/ish ~Coaril, C a r 1 C u .s I a f r to n I? to s e it, Chief of tin,
Intprrral E'Ihjopian Air hirer, performed a record non-stop flight from Stock-
holm to Adtlis 4haba. The flight tins made in a Saab Safir, a plane ivi.tlt
it/n-f Count con Bosco erns very funtili.ar front service flights in Ethiopia
axtd torn, his uisi.ls Ito Sic,,rlen.
In tie following article rig have collected sonic data on. the flight, chiefly
Front r ount Rosen .s own reports,
()it Friday, May 9, at (l4.09 hours the Sa fir
took off from Brrnnma AirfiId in Stockholm.
The place hecatoe airborne after 40 seconds,
with at take-off run of about 9(;,l) m or five time
the normal run. The take-of weight was exeep-
lisnall% heavy however, he:og 1,500 kg as
againsl 995 kg normally. titer lifting, the
plane climbed slowly, got on to its course and
was soon nut of sight the record flight hall
hi-gun.
I'hc idea oI. the non-stop flight originated with
Cmut1 Rosen himself'. It occurred to him while
()It it visit to Sweden coo ley ed will] the
delivery of Ill- sixth Safir to Ethiopia. At
first he iolended to make iulc -mediate landings
ill Rollie and Cairo, but after , heckiug the hinge
schedules and flying distam'es he found that it
would be possible to make Iiu? flight non-stop.
Rosen also had unqualified onfidenve in the
Safir and he considered the po'iiurinarv coudi-
licros to be entirely la%(tit raIwic for this long
distance flight of 0.220 kill which, if snrcessful,
would set a new long dislaurci record for air-
planes (if' Ibis clam. Airplanes ire rated in clas-
ses hared exchtsiycly on the ex tinder volume of
Ow engine. The tiufir's (;ipso Major If) engine
having it vole mie of 6.13 litres a as rated tit the
2 C class covering engines with cylinder volunic
belwuen -1 and 6.5 litres.
Preparalirnts for the flight v ere only started
a forlnight before the lake-off and, as far as
Rosen hinrsellf, was concerned, .'onsisted chiefly
in obtaining permits for the flight across the
countries enroule, that is 1n say, along the line
Stockholm Stolp Vienna Zagreb Split- Sol-
htni-- VG udi Haifa khartoum Addis Ababa.
The sclieclnledl route would lake Rosen between
the Alp:, and the Carpathians and would thus
enable him to avoid flights at high altitudes. Up
to the last moment, however, it looked as Ihough
he "mild have to lengthen the air route as he
etas informed that lie could not obtain it permil
for flying across Russian-oeecrpied ierrilorv
within it sixnionlh period. But the matter was
settled satisfactorily after personal contact hv-
t:ween Rosen and the Hessian Ambassador in
Stockholm. The latter was very interested in
the flight and wished Count Rosen luck in his
attempt.
Count Curl Gustaf run Rosen in the tiafir jasl before
t1kin5 off frunr front 1110
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Preparations for the Safir were not very exten-
sive. It was a series-assembled plane with a
wooden propeller, the only equipment other
than the standard being the extra fuel tanks
which were placed in the two passenger scats
of the cabin. The plane also had it directional
gyro and a gyro horizon for blind flying. A few
days before the flight a take-off test with it flying
weight of 1,425 kg was made and the result was
entirely satisfactory.
Preparations had been rushed through as much
as possible to take advantage of the moonlight for
night flying. There was a full moon oil May 5,
but it was impossible to complete preparations
by that date. It was hoped therefore, that the
half moon on May 9 would give sufficient light
for orientation.
Count Rosen arrived at the airfield on Lite
morning of the take-off refreshed by a 10-hour
sleep. After the engine had been warmed, the
tanks were filled and sealed. The total amount
of petrol carried was 947 litres. The extra tanks
filled the cabin, but Rosen had full freedom of
movement after he had settled himself in Lite
pilot's seat with his parachute and safety jacket.
Provisions consisting of 10 12 sandwiches, a jar
of grapefruit juice, a jar of pineapples and ther-
mos bottles with tea, whortleberry soup and
corned beef were stowed away. For emergency
purposes p.henedrin tablets were provided but
Rosen did not intend to use these before he had
completed at least 24 hours' flight, since lie
knew he could cover that distance without resort-
ing to the use of drugs.
So the Safir rolled out and Lite take-off was
excellent. Across the Baltic he kept to an altitude
of 200 m and over. Germany he rose to 10(1 500 m
and finally over Africa lie held an altitude of
about 1,500 in. The speed varied between 180
kni/h and 207 km/h. The weather was fine in
After the record flight the plane rolls out on ill(, rain-
soaked field of Addis
100M 0025-8
,Native mechanics take the record-making machine in
charge
Stockholiu and held until off Crete, where Rosen
encountered clouds and darkness. Over the Libyan
desert sand storms were raging, and for len hour-
lie was obliged to trust entirely to his instrucneuts
in blind flying. Thus, the moonlight was of nn
assistance, and at Wadi Ilalfa where he had to
change his course lie had to take his bearings in
the dark and without ground control. In the
hot sand storm the temperature of the oil rose
to 95" (1, and the oil tank being located ill tit(-,
cabin, the beat became somewhat unpleasaui.
On the whole, the tell hours of blind flying in
pitch darkness, without moon or stars, in a hop,
stormy atmosphere were far from pleasant Rosen
reported in a cable.
From Khartoum onwards to Addis Ababa lite
weather was fairly good, however, apart from
some violent rainstorms in the Ethiopian ncomi-
tains. here lie also experienced icing of the
carburetor as had been Lite case over the Baltic
and the Mediterranean, but this was easily reme-
died with the help of warm air. The large addi-
tional load made the plane tail heavy during
blind flving, but otherwise Lite conditions were
normal. The instruments worked perfe'.elly and
the windshield was clean and clear all through
the flight.
At 11.01 hours Swedish time on Salurdav
morning, 30 hours and 52 minutes after the take-
off, the Safir landed oil the airfield of Adcli-
Ababa. In spite of violent thunder storms or