Researching the Luftwaffe through Prisoner Interrogations

[Bruce Dennis]

"SECRET A. D. I. (K) Report No. 125/1945
THE FOLLOWING INFORMATION HAS BEEN OBTAINED FROM P/W
AS THE STATEMENTS HAVE NOT AS YET BEEN VERIFIED, NO
MENTION OF THEM SHOULD BE MADE IN INTELLIGENCE
SUMMARIES OF COMMANDS OR LOWER FORMATIONS, NOR SHOULD
THEY BE ACCEPTED UNTIL COMMENTED ON AIR MINISTRY
INTELLIGENCE SUMMARIES OR SPECIAL COMMUNICATIONS.

G.A.F.NIGHT FIGHTERS.
RECENT DEVELOPMENTS IN GERMAN NIGHT FIGHTING.
1. Between the opening of the Rundstedt offensive on 17
December 1944 and the night of 1st January 1945, fifty-nine
German night fighter aircrew captured on the Western Front
were brought to England for interrogation by A.D.I.(K). Of
these prisoners, ten were selected as being suitable for
special interrogation with the object of investigating current
German tactics, and the extent of their deviation from methods
employed up to the end of November and reported in A.D.I.(K)
508, 599, 620 and 700/1944.
2. The present report is based on the interrogation of these
ten prisoners, who came from III/N.J.G.1, II and III/N.J.G.2
and II, III and IV/N.J.G.3, and of whom one had recently spent
some time at the G.A.F. radar experimental station at
Werneuchen. In addition, there was one prisoner who had spent
one year as a ground radar mechanic with I/N.J.G.4 and had
then transferred to the Schulstaffel of the same unit to train
as a radar operator. The Schulstaffel had been dissolved at
the end of October 1944 and its personnel posted to the
infantry; this P/W fell into Allied hands as an unwilling
member of the Waffen SS.
3. From interrogation of previous night fighter prisoners -
captured between September and the end of November 1944 - it
has been amply proved that the German night fighter force has
been at a loss to overcome the successful Bomber Command
spoofery and radio countermeasures and as yet has made no
progress in its efforts to overcome this disadvantage.
4. From the present interrogations there are signs that the
Germans, not content to let the matter rest as it is, are
striving to gain the upper hand over Bomber Command by the
introduction of at least two new measures. One of these,
discussed in the following paragraphs, is the employment of
Bernhardine beacons for the dual purpose commentary and
navigation, and the other - as yet in its early stages - the
probable introduction of a new type of search equipment, the
SN 3. Details of the latter are at present lacking, but
evidence suggests that it may be of the nature of centimetre
A.I.

BERNHARDINE – FuGe.120.
Earlier Vicissitudes.
5. As far as G.A.F. prisoners are concerned, Bernhardine is
no innovation, as early as May 1942 hazy allusions to this
form of navigational aid were made by prisoners, but the first
mention of Bernhardine by name was made by an officer of
1(F)/121 captured in October 1943 (A.D.I.(K) 498/1943;
thereafter nothing further was heard until K.G.66 opened its
pathfinder operations over England early in 1944.
6. A prisoner from 5/K.G.66 captured in England on 25th March
1944 gave an account of Bernhardine which, in the light of the
present interrogation proves to have been remarkably accurate
(A.D.I.(K) 187/1944, paras.19 – 24)
7. In October 1943, 5/K.G.66 had had 1 Do.217-M equipped with
Bernhardine, but after some experiments the experts had come
to the conclusion that the apparatus was not sufficiently
accurate for pathfinder operations; the P/W concerned had
heard later that work on the ground installations had ceased.
8. In spite of continued interrogation of subsequent
prisoners, nothing more was heard of Bernhardine until late in
December 1944. The capture of a prisoner from III/N.J.G.1 on
17th December 1944 and other prisoners from II and III/N.J.G.3
later in the same month has now revealed that Bernhardine is
being seriously considered - if not already used - not only as
an aid to night fighter navigation but as a source of the
commentaries.
Introduction of Bernhardine to Night Fighting.
9. Some time in October 1944, crews of 8/N.J.G.1 were given a
preliminary lecture on Bernhardine in which its principles
were explained, they were told that it was no new discovery
but would shortly be introduced to night fighting. In
III/N.J.G.3 crews had also been given frequent lectures and by
November some of the aircraft of that Gruppe already had the
necessary apparatus installed.
10. According to prisoners who attended these lectures, the
transmissions from the ground station take the form of a
conventional twin lobe polar diagram with an equisignal area
and with a very small amount of rearward radiation. A signal
transmitted from the ground station once every minute is
translated by the airborne apparatus into a teleprint message
on a paper tape giving the QTE (true bearing) of the aircraft
from the ground transmitter followed by a further image in
figures and letters which is a Divisional commentary of the
type at present broadcast by the high powered W/T beacons.
11. It was explained that the Bernhardine transmitters would
operate on 32 frequencies between 30.0 and 33.1 mc/s, and that
the signal would be received through the normal E.Bl.3 in the
aircraft. Thus the first 32 of the 34 spot frequencies of the
E.Bl.3 would be used for Bernhardine whilst the remaining two,
33.2 and 33.3 mc/s, would be retained for blind landing
purposes.
12. It is claimed by P/W that Bernhardine signals are
unjammable and that transmissions have a range of 400 - 500
kilometres.
13. A captured night fighter map, recovered from a recent
crash in Belgium and issued by the signals officer of N.J.G.3,
was marked with Bernhardine transmitters at approximately the
following pinpoints;-
N° 0(?) Berlin 52°13'N;13°6'E
N° 8 Alkmaar, Holland. 52°42'N;4°38'E
N° 9(?) Leck 54°41'N;9° 2'E
N° 10 Thisted, Denmark. 56°42'N;8°33’E
N° 11 Breslau 51°25'N;17°5’E
N° 12 Pilsen 49°45'N;13°15’E
14. A further indication that Bernhardine may already be in
operational use was found in a file of signals orders from an
aircraft of II/N.J.G.1 shot down on December 31st. On the same
page as the usual numbering of the Y-line frequencies was
another column headed "Kanäle" (= channels); the channels were
numbered from 1 to 32 and to each number was appended a
frequency, commencing with 30.0 at No.1 and rising by .1 mc.
to 33.1 mc/s at No.32.
15. Both of the above documents have been forwarded to
A.I.4(b).

Airborne Apparatus.
16. The Bernhardine apparatus in the aircraft is contained in
a box measuring some 60 cm in width, 30 cm in height and 20 cm
in depth, placed in the JU.88 in some cases to the right of
the W/T operator on the lower port wall of the fuselage and in
others to the left of the W/T operator or in the forward
instrument panel.
17. The front of the box has a wide glass-covered slot about
40 cm. in length and 12 cm. in depth along which the paper
tape travels from right to left after the necessary data have
been printed upon it by a teleprinter contained in the box.
The on-off switch for the apparatus, marked FuGe.120, is
placed on the R/T operator's switch panel, and is used in
conjunction with the click-stop frequency selector for the
E.Bl.3.
18. From evidence supplied by the present P/W it is possible
to give a description of the Bernhardine display and of the
exact data which it supplies. An impression of the Bernhardine
display is given below; it will be seen that the printed tape
is divided into three horizontal sections, on the uppermost of
which appears a series of close vertical lines shortening at
intervals to a "V", on the central section a reading in
degrees, and on the lower a coded image which is the
commentary. One simultaneous printing of these sections takes
place during ten seconds of every minute, the tape remaining
stationary for the remaining fifty seconds, after which the
process is repeated.
19. In the lectures on Bernhardine it was stated that the
ground transmitter makes one full revolution of 360° in sixty
seconds; a section of the pattern of the ground transmission
is repeated on the tape in the form of the series of vertical
lines, the equisignal zone being represented by the apex of
the "V".
20. In each printing lasting ten seconds a sector of 60°
appears on the tape and in every case it contains a repetition
of the equisignal zone. The reading in degrees appears in the
central section of the tape in numbers representing 10's of
degrees, and the point opposite to which the apex of the "V"
is printed represents the bearing in degrees of the aircraft
from the transmitter. Accuracy of bearings was stated to be
within 0.5°.
21. A recognition letter is allotted to each transmitter and
is repeated on the tape at every 20° on the scale; in the
sketch the letter X - the recognition for the Leck transmitter
is shown.
22. The commentary in the lowest section appears in each 10-
second printing as a group of a maximum of ten letters and
numerals, inclusive of two crosses denoting the beginning and
end of a message. Should a message be of more than ten
characters it wi11 be continued in the succeeding printing, a
cross appearing at the end of the message.
23. Thus, the commentary message shown in the sketch, + 40 KA
27 100, just falls within the ten-character limit if the final
+ denoting the end of the message is omitted. The latter is
therefore carried forward and appears at the commencement of
the next printing; it denotes simultaneously the end of the
one message and the beginning of the next. It was stated that
a single message could be continued over three or four
printings.
24. The commentary always appears in a standard order;
analysis of the typical message shown in the sketch is as
follows:-
25. It will be noted that the form of this commentary is
exactly the same as that at present put out by the Divisions
on the high powered W/T beacons (see A.D.I.(K) 599/1944 para.
57).
26. The present P/W had been told that, in addition to the
Divisional commentary, instructions to individual formations
of night fighters would be transmitted by the Bernhardine and
printed on the lowest section of the tape. How, in such a
case, the aircraft would be tracked or how the orders by the
subordinate units would be coded, they did not know.

Operational Use.
27. The aircraft set is switched on soon after take-off, so
that the bearing transmitter can be constantly watched. If the
+ = beginning of message
40 = height of head of bomber stream in 100’s of metres
KA = fighter-grid position of head of stream
27 = course of formation in tens of degrees
100 = estimated number of aircraft
W/T operator wants the fix, he switches over to the
transmission of a second Bernhardine station for a gross
bearing; it was stated, however, that quicker and more
favoured method was to obtain a simultaneous cross bearing
from a high powered beacon through the PeilGe 6.
28. As far as these prisoners knew, only the Bernhardine
stations at Berlin and Leck are so far capable of transmitting
a commentary and flying instructions; the latter station was
only modified in this way at the beginning of November 1944
and aircraft of 9/N.J.G.3 made several test flights, usually
taking off from Uetersen at about 0230 hours and remaining
airborne for some four hours.
29. The present P/W of 9/N.J.G.3 had not taken part in these
flights, but after the tests he had seen the tape, which he
described as being printed on white paper in red letter,
4 - 6 mm. high as clearly as with a typewriter. He was told
that there was sufficient tape to allow of continuous
operation for 4 hours 20 minutes.

SIGNALS TRAFFIC.
German Spoof Signals.
30. An aircraft of 7/N.J.G.3 shot down in Belgium on January
1st carried a signal order on which appeared the word
"Orgelpfeife" (= organ pipe). Interrogation of all the present
P/W elicited the fact that Orgelpfeife is the codeword for
spoof R/T and W/T traffic passed between small numbers of
aircraft and the ground with the object of simulating large
numbers of night fighters in operation.
31. According to a P/W of 9/N.J.G.2 Orgelpfeife was
introduced in that unit, in mid-November; one crew in the
Staffel had received special briefing and usually operated the
spoof traffic. In operating R/T spoof, this crew’s duty was to
imitate a large number of night fighters operating by the
simple expedient of all four members of the crew taking turns
to speak, each using different callsigns.
32. It was said that the pilot of the crew in question,
Oberfeldwebel GELLNER was something of an actor and was able
to imitate various German dialects and different voices; P/W
claimed that the single Aircraft could simulate as many as
twelve night fighters.
33. The Orgelpfeife aircraft operated under Y control, since
such importance was attached to its position in relation to
the raiding force; the spoof aircraft patrolled an area near
the estimated target and as the raiding force was approaching
the target, the simulation of night fighters operating
commenced.
34. According to P/W the spoof aircraft carried large
quantities of Düppel (Window).
35. It seems that only one aircraft in a Staffel operates
Orgelpfeife; this was certainly the case in III/N.J.G.2, and
another P/W of III/N.J.G.3 stated that similar conditions
prevailed in that Gruppe.
36. None of the present P/W could give any useful information
on the method of coding the Orgelpfeife traffic, but it was
stated that the briefing usually gave two codewords or groups,
according to whether the spoof was R/T or W/T, and the crew
was to ignore all orders from the ground except those preceded
by the operative Orgelpfeife codewords or group.
37. In the captured briefing sheet mentioned above, the
codewords for 7/N.J.G.3 on the night of December 31st were
"Elfenbein" for the aircraft and "Hallore" for the ground.
38. A P/W of 9/N.J.G.3 stated that early in December R/T
silence had been enforced amongst the normally operating night
fighters of that Staffel.

Defence of the Ruhr by N.J.G.1.
39. The four Gruppen of N.J.G.1 have been allotted the
special task of defending the Ruhr in night attacks by R.A.F.
Bomber Command, and to achieve this aim all the Gruppen are
based strategically at airfields in that area.
40. In operations over the Ruhr the Gruppen are not
controlled separately as would normally be the case, but
operate under the central control of a special Geschwader
commentary put out on a M/F and an alternative V.H.F.
frequency; the latter, however, is almost invariably jammed.
41. This commentary consists of tactical instructions to the
aircraft as well as reports on the general situation;
according to P/W, the latter are not based on a Divisional
picture of events, but on data supplied by the Ruhr Flak
defences.
42. When a Mosquito force is reported over the Ruhr area, and
providing that flying conditions are suitable, all aircraft of
N.J.G.1 are put up and ordered to orbit any of the beacons
Börse, Bruno, Achmed, Gemse, Heide, Schnake, Paule, Ratte and
Drossel to await further events.
43. In case of jamming of both channels of Geschwader
control, two of these beacons, Achmed and Paule, are set aside
for transmission of the Geschwader commentary. P/W also heard
that a further alternative H.F commentary is to be put out on
a 20 kW transmitter whose signals will be superimposed on a
Cologne broadcast programme.
44. The aircraft of N.J.G.1 usually orbit the beacons for
about an hour, and if by then no attack by four-engined
bombers has materialised they are recalled; upon returning to
base, the aircraft are immediately refuelled so that should a
further attack be made a fresh sortie can be initiated
immediately.
45. In the middle of December some 50% of the aircraft in
N.J.G.1 were equipped with two white LC.50 flares carried
externally under the outer rings, and in the event of a major
bombing attack on a Ruhr objective these aircraft were to make
for the target and lay the flares at the operative height of
the bombers, so that the remainder of the night fighters could
quickly close in the area for visual attack.
46. The flare-carrying aircraft were to be given an X-time
for arrival over the target to coincide with the arrival of
the bomber stream; at this time the Flak would have orders to
cease fire, the flares would be laid and the night fighters
would go in to attack.
47. Importance was attached to the flare-carrying aircraft
arriving exactly at X-time, since a previous arrival would put
them and the remainder of the night fighters in danger of
being shot down by the Flak, and a late arrival would
jeopardise the operation.
48. In such a case where the aircraft of N.J.G.1 had been put
up against a spoof attack of Mosquitos and a four-engined
attack developed against targets outside the Ruhr, the
Geschwader commentary would transmit the codeword "Diogenes",
at which the aircraft would revert to their respective Gruppe
commentaries and would operate against the new attack in the
normal manner.
49. Crews of the flare-carrying aircraft were instructed that
in defending targets outside the Ruhr they could use their
flares, but only if they were certain of the true target.
Jamming of Commentaries.
50. Prisoners of II and III/N.J.G.3 stated that the Gruppe
commentaries were not seriously jammed in the Hamburg area;
although R/T could occasionally be heard, however, crews
relied mostly on the morse commentaries.
51. They stated that intensity of jamming varied considerably
from night to night. They could not understand the reason for
this since they had been officially told that the jamming had
been D/F’d and traced to the London area.
Verbandsführer (Formation Leader).
52. From the present P/W there are again conflicting reports
on the success or failure of the system of flying in formation
with a leader aircraft (A.D.I.(K) 700/1944, paras.34 – 49).
53. Whilst one P/W of N.J.G.3 stated that the system had been
working well in that Gruppe up to mid-December and that leader
aircraft operated under Y control, another prisoner, of
8/N.J.G.1, stated that in his unit the system had proved
unworkable and had been dropped in October. He gave as one
reason the dislike by the more experienced crews who flew as
formation leaders of acting as flying beacons, with the
attendant danger of being homed on by Mosquitoes.

I.F.F.
54. Much has already been said about the FuGe.25a in recent
A.D.I.(K) reports but nevertheless interrogation has continued
as to the conditions under which the apparatus is or is not
switched on during operations. One P/W of 8/N.J.G.1, based at
Düsseldorf, stated that if no intruders were reported at the
time the night fighters were ordered up for an operation, he
would switch on the FuGe.25a at take-off and keep it operating
until well clear of the airfield.
55. During operations he would have the instrument turned
off, but on returning to base would again switch it on shortly
before reaching the airfield - provided no warning of
intruders was in force.
56. A P/W of 9/N.J.G.3 knew of the British air-to-air I.F.F.
and knew that R.A.F. A.I. included a button which, upon being
pressed, identified the friendly aircraft on the A.I. picture.
57. Crews in this Staffel were told that a German air-to-air
I.F.F. was shortly coming into operation, but no further
details were given.
58. A prisoner of 11/N.J.G.3 remembered having seen a note in
a G.A.F. intelligence summary stating that the R.A.F. was
using infra red air-to-air recognition.

Hermine Beacons.
59. One of the present P/W had first heard of Hermine V.H.F.
beacons in March 1944, and at the time had learned that these
were radio beacons of new type from which pilots of singleengined
aircraft could obtain bearings.
60. He stated that the beacon, which has an effective range
of 200 – 300 kilometres, rotates through 360° in about three
minutes. The beacon transmits a continuous tone over about
359° with a silence zone of 1° which sweeps through 360° as
the beacon rotates; additionally a "speaking clock" counts
continuously from 1 to 360 and the continuous tone is
superimposed over this speech.
61. The pilot in the aircraft hears the continuous tone and
the counting on the FuGe.16Z, but hears the bearing spoken
clearly when in a line with the silence zone; he thus hears
his bearing to the beacon.
62. It will be remembered that prisoners of the Wilde Sau
single-engined night fighter unit I/J.G.301, captured in July
1944, had made mention of these radio beacons, albeit not by
name. The Kommodore of a single-engined day fighter Geschwader
had suggested that "Hermine" is derived from Oberst HERMANN,
founder of Wilde Sau night fighting.

INTERCEPTION EQUIPMENT.
Spot frequencies of SN.2.
63. The word "Streuwelle" in conjunction with SN 2 has been
mentioned for the first time by the present batch of
prisoners. Although none was able to define the word
Streuwelle or its origins, one suggested an alternative word
"Frequenz"; A.D.I.(Sc.) has supplied an agreed translation of
"Streuwelle" in the term "Spot frequency".
64. It has already been reported that in I/N.J.G.2 an attempt
had been made to reduce the effects of electrical jamming by
mounting the SN 2 aerial arrays diagonally instead of
vertically. These prisoners confirmed that this had also been
the case in other units, but the present interrogations have
established that this arrangement of aerials has no connection
with the spot frequency of the SN 2. In many cases prisoners
have known the differing aerial arrangements to exist in
several aircraft all equipped with SN 2's of the same spot
frequency.
65. These prisoners knew of three Streuwellen at present in
operational use, namely 4, 5 and 6; in two units, 8/N.J.G.1
and IV/N.J.G.3 some of the aircraft carried No.6, and other
prisoners stated that aircraft of their units were equipped
with 4 or 5 or a mixture of both. In 5/N.J.G.3, for example,
Streuwelle 5 had superseded 4, whilst 8/N.J.G.1 was equipped
with a mixture of 4 and 6, the latter having been delivered in
October.
66. It is worth noting that aircraft equipped with
Streuwellen 5 or 6 are forbidden to fly over enemy territory
unless the boxes have previously been removed; no such
security measures, however, exist with Streuwelle 4.
67. One prisoner had heard that a JU.88 equipped with SN 2
and Flensburg had landed at an airfield in East Anglia last
summer and that the British were therefore in possession of an
SN 2. He naturally assumed that the latter apparatus was of
Streuwelle 4. Upon being asked how it was known that a German
night fighter had landed in England he replied that the
information had been given by British prisoners in Germany.
68. Not one of the present P/W could supply the respective
frequencies of Streuwellen 4, 5 and 6, but the radar servicing
mechanic P/W, who had been with N.J.G.4 up to the end of
October, was able to give a few details of 4 and 5; up the
time when he left the unit he had not encountered No.6.
69. He was certain that the frequency of 5 was slightly
higher than that of 4; No.5 has one more induction coil and
has a range exceeding No.4 by 5 kilometres, being provided
with an extra switch giving two range pictures, one at 5 km.
and one at 10 km.
70. He and other prisoners stated that no matter which
Streuwelle, 4, 5 or 6, is installed in an aircraft, the aerial
array remains unchanged and in all cases the same CRT's and
the same electrical length of connecting cables are employed.
71. The ground radar mechanic stated that outwardly there is
little difference between the three Streuwellen, and to avoid
confusion by the ground staff all boxes have the appropriate
number painted on the back; the boxes of different Streuwellen
are not interchangeable.
72. An example of the effects of jamming on the differing
Streuwellen was given by one of the present prisoners. In May
1944 all aircraft of his unit were equipped with Streuwelle 4
with provision for the alternative frequency. In July 1944,
however, Window jamming made the set useless.
73. In October 1944 Streuwelle 5 and then 6 were delivered,
both with the alternative frequency; these, however, were
seriously jammed by the so-called Rauschsender (electrical
jammer). It was found, however, that the remaining SN 2's of
Streuwelle 4 were not so seriously upset by electrical
jamming, and the result was that many crews asked for No.4
back again and their wish was granted.
74. According to the radar mechanic, the C.R.T's used in the
SN 2 are manufactured by both Lorenz and Siemens Nürnberg; the
latter are the more satisfactory in service.
75. One P/W had spent six months up to May 1944 installing
SN 2's in Me.110’s at Werl; he stated that installation work
for Ju.88’s was carried out at Gütersloh.
Serviceability of SN 2.
76. Considerable trouble in the servicing of the SN 2 was
experienced in misty or wet weather; the chief source of
trouble was rain water percolating into the pulse distributor
at the base of the antennae and was the cause of squints and
the blowing of valves.
77. In units recently examined, night flying tests are no
longer made; in the experience of one P/W of II/N.J.G.1 some
30% of the SN 2's were found to be u/s if the unit had been
stood down for more than three or four days.
78. Should radar equipment be found to be u/s after an
aircraft has taken off on an operation, the order is that the
sortie must be completed. This is a state of affairs which
rattles the crews, particularly if the SN 2 is not working and
they are robbed of backward cover.

SN 3.
79. As compared with prisoners captured up to the end of
November 1944, the present P/W gave the impression that
developments in the SN 3 have reached a further stage.
80. No prisoner has yet been encountered who has seen an
SN 3, but several had heard some scraps of information. It was
stated that the aerial array for this set is carried inside
the aircraft, and that Major SCHMAUFER, Kommodore of N.J.G.4,
is already flying an aircraft with this new search equipment.
81. There is no doubt that the Germans are in possession of
details of British centimetre A.I. and it has recently been
freely discussed by G.A.F. aircrew under the name "Grille"
(= grid).

TAIL WARNING.
SN 2 Tail Warning.
82. The present P/W were able to add considerably to
information obtained on night fighter tail warning equipment
and set out in A.D.I.(K) 700, paras.13-16. The present
interrogations, leave no doubt that the tail warners now
extensively fitted to German night fighter aircraft are a part
of the SN 2 equipment and that the picture appears on the SN 2
azimuth tube.
83. No height or bearing, but only a range reading can be
obtained from the backward aerial; forward and backward
displays do not appear simultaneously on the SN 2 tube, but
the set is provided with a switch which can select one or the
other. The method employed by the radar operator is therefore
to search for contacts with the forward aerials whilst
occasionally switching over to rearward aerial to see if an
enemy night fighter is following.
84. A tail warning tactic recommended to crews of III/N.J.G.1
is one of not taking immediate action when a rearward contact
is picked up, but of waiting until the range begins to close
in. When this occurs, the pilot increases speed and if the
blip closes in to 600 metres the pilot then takes evasive
action.
85. In the above-mentioned unit evasive action has been
ordered to take the form of a 180° hard turn to port or
starboard. If the pursuing aircraft has been seen by the crew,
the turn will be made according to its position; when the
pursuer is to port, the pilot of the night fighter will turn
in to port, or vice versa.
86. Previously, the tactics of the night fighter in those
circumstances was to peel off towards the pursuing aircraft,
but this resulted in losing 1500 to 2000 metres in height
which took about ten minutes to regain.
87. The newer tactic described above was ordered in
III/N.J.G.1 late in November to obviate this loss of height
and time and in that unit at least, the tactic of peeling off
is now forbidden except in extreme urgency.
88. A number of P/W knew the SN 2 tail warning as the D (or
Dora) Zusatzgerät (= the Dora attachment).
Fu.Bl.2 as Warning Device.
89. Yet another piece of German Airborne radio equipment, the
Fu.Bl.2 has been added to the list of sets that are capable of
giving a warning of approach of an aircraft.
90. Three P/W had heard that if the Fu.Bl.2 is switched on,
the red marker beacon warning lamp lights up when a radarequipped
aircraft is in the immediate vicinity.

Naxos as Tail Warning.
91. Crews of 8/N.J.G.2 had recently been told officially that
Naxos is capable of acting as a warning of the presence of
enemy A.I.–equipped aircraft. No such information had been
given to any of the other units examined during the present
interrogations, and none of the other prisoners knew that
Naxos had such capabilities.
92. It was pointed out by the one P/W concerned that Naxos
can do no more than give warning of A.I. radiation on a given
bearing, and range of the source of the radiation cannot be
measured; a bearing reading would, however, at least indicate
the probability of an enemy night fighter in pursuit.
HOMING EQUIPMENT.
The Naxos as an A.I. Instrument.
93. Since the first mention of Naxos by a prisoner in July
1944 (A.D.I.(K) 407/1944) and in the subsequent fuller account
of other aspects of Naxos and its tactical use (A.D.I.(K) 508
and 620/1944) it has frequently been reported how some night
fighter pilots have claimed to have used Naxos as an A.I.
instrument. There have been frequent claims usually by
lecturers at Werneuchen, that night fighter crews have shot
down four-engined bombers with their upward armament without
having used SN 2 at any time during the pursuit, but no
prisoner has been encountered with first-hand knowledge of
this fact.
94. Amongst the present P/W was a crew of 4/N.J.G.2 who had
six victories, each with the help of Naxos to a greater or
lesser extent. On five occasions they had located the bomber
stream with Naxos and had made the final approach with SN 2.
On the sixth occasion, however, they had shot down a fourengined
bomber with upward armament after an approach with the
sole use of Naxos.
95. In an attack on Berlin in March or April 1944, this crew
took off from Twente and flew towards the Baltic coast. At
about 54° 30' N; 11° 30' E some eight H2S contacts were
obtained from a height of 4,500 metres; one of these was
selected by manipulation of the Naxos brilliancy knob and
followed to about 13° E and then southward over Berlin.
96. The contact was held and followed from Berlin towards
Leipzig whilst the night fighter gradually approached its
target by making contact with the edge of the H2S cone,
throttling back to avoid penetrating too far and being
detected, then climbing and again making contact with the cone
in horizontal flight; a visual of the R.A.F. bomber was
obtained near Frankfurt-am-Main when the night fighter was at
a height of 7,800 metres.
97. The pilot closed in to make the attack but missed the
bomber; after a second unsuccessful attempt, the rear gunner
of the bomber fired a burst but missed. On the third attempt
by the night fighter the bomber was hit and was claimed as a
victory by this crew.
98. Early in October H2S contacts in the Naxos began to be
fewer, and such contacts as were made invariably disappeared
abruptly. The pilot who, incidentally, had a very high opinion
of his own capabilities, put this down to his radar operator
and blamed him for inefficiency; the result was that the crew
was continually quarrelling and was engaged in heated argument
when shot down.

The Naxos Aerial.
99. The radar mechanic had been with I/N.J.G.4 had attended a
Naxos course at Werneuchen in May 1944 and subsequently had
had some experience in servicing the apparatus. The
interrogation of this P/W on the subject of Naxos was carried
out with the co-operation A.I.2(g), with the result that he
was able to add some useful details to the substance of
A.I.2(g) Report No.1734.
100. In August 1944, Naxos began to be delivered to
1/N.J.G.4. The Naxos-equipped Ju.88’s first delivered to the
unit had the aerials installed on the after part of the
fuselage, but in later deliveries, the plexiglass dome
containing the aerials was fitted to the jettisonable hood of
the cabin – a position known as "Ausführung A". It was feared,
however, that the hood would be difficult to jettison and in
some aircraft the original position of the aerials was again
adopted.
101. When this P/W left I/N.J.G.4 in October 1944 the display
unit in use was the Naxos-Post, but he did not know which type
of aerial array was associated with this display, and he knew
of no further designation of any part of the equipment.
102. When Naxos was first introduced to the unit, the aerials
consisted of two plastic rods, of a material known as
Trollitul, of square cross-section with rounded ends and
measuring some 40 cm. in length and 5/6 cm in thickness. This
type of rod was, however later superseded by one of circular
cross-section with a diameter of 3-4 cm. and of the same
length.
103. These aerials were fixed parallel to one another and
about 3 - 4 cm, apart, being held in position at their central
points by a bakelite clamp made in two halves. Rotation of the
aerials was in a clockwise direction about an axis which was
vertical when the aircraft was in flying position, the aerials
cleared the aircraft skin by about 5 cm. Speed of rotation was
estimated by P/W at about 3000 r.p.m.
104. The aerials were mounted on a vertical axle running in a
ball Bearing flush with the aircraft skin and driven directly
from an electric motor which P/W recognised as being similar
to that illustrated in A.I.2(g)1734.
105. A copper lead came away from each plastic aerial rod and
joined the axle on which the aerial rotated; between the ball
bearing and the electric motor, a right-angle plug led the
signals received by aerial out of the axle and through a length
of single 1 mm. copper high tension wire to the Abgleichkasten
(cable matching box). P/W had also heard the term "Hochpass
Einrichtung" in connection with this box.
106. The cable matching box was shaped in cross-section like
a half ellipse and measured about 25 x 8 x 8 cm. The screws
securing the lids were sealed, and if any fault developed, the
box had to be sent away to the Gruppe repair and servicing
depot; the Staffel servicing staff were forbidden to break the
seals.
107. This P/W had seen a box open at the Gruppe at the
servicing depot and remembered that it contained a special
type of coil and detector of a type similar to that shown in
the A.I.2(g) Report. He was under the impression that there
were six such detectors.

Daily Inspection of Naxos.
108. The daily inspection of Naxos consisted of running up
the aerial array on ground batteries and using an ordinary
buzzer working from a torch battery as the transmitter. The
oblong box containing the buzzer had to be held so that one of
its ends, called the Strahlenseite (radiating end) pointed
towards the aerial and was in their plane of rotation. A
lightening of the appropriate part of the Naxos trace showed
that Naxos was in order.

AIRBORNE PLOTTING TABLE.
109. In the autumn of 1942 one at the present P/W had taken
part in some flying trials of a television device which was
being tried out at Werneuchen. For the purpose of the trials a
television receiver which was to repeat an 18 cm. square
picture of the Seeburg Tisch of a night fighter box, was
installed in a He.111.
110. In the trials reception was remarkably good and a clear
definition was obtained, the two spots of light representing
the friendly and enemy aircraft could be seen, but the only
means of distinguishing between the two was by the insertion
of a cardboard arrow on the Seeburg Tisch. In a similar way
cards bearing written vector instructions were placed on the
plotting table in view of the camera.
111. At that time the Germans were experiencing no
difficulties with box-control of night fighters and since
continual troubles were experienced with the television
transmitter the trials were discontinued toward the end of
1942.

GERMAN H2S - THE BERLIN GERÄT.
112. The same prisoner had heard of a German version of the
H2S called "Berlin" which he understood, was an improvement on
the British apparatus.

GERMAN KNOWLEDGE OF 100 GROUP R.A.F.
Activities.
113. In lectures on night fighting given to 8/N.J.G.1,
7/N.J.G.2 and 9/N.J.G.3 in October and November 1944, crews
had been given some details of the activities by 100 Group
R.A.F. which gave them the impression that the German Higher
Command has the greatest respect for the efficiency of those
responsible for planning that unit's activities. Some details
of these lecturers which prisoners from the above units could
remember show that the Germans are now accumulating
considerable knowledge of the equipment and tactics of 100
Group.
114. At recent briefings to 8/N.J.G.1 great importance had
been attached to the part played by 100 Group, and the many
occasions when warning of an impending attack had been given
and the aircraft had been airborne only to find the advertised
raid melt away, were now ascribed to the wizardry of that same
unit.
115. It was stated that the Group is equipped with Mosquitoes
and Lancasters - amongst whose crews were some expert bombers
- and that both these aircraft types carry the jamming
equipment which together with ground jammers upset the
commentaries and the SN 2. Long range intruders were also
ascribed to the same unit.
116. In a lecture on 100 Group given to 7/N.J.G.2 early in
November 1944, crews were told of so-called 'D' aircraft which
has the duty of putting out spoof R/T and W/T instructions to
German night fighters; one instance was related in which a
whole night fighter Gruppe had returned to base as a result of
spoof orders by one of these D aircraft. The W/T operators at
the 1ecture were advised that if they paid sharp attention to
their R/T and W/T signals they would be able to distinguish
between the false and genuine instructions.
117. It is now widely known by G.A.F. night fighter aircrew
that Mosquitos are equipped with a search equipment, the
Grille (= grid), that has a range of 15 kilometres (about 10
miles) and is said to work on a frequency of 3 cm. An
interesting extra piece of information given in these lectures
was that Grille was capable of homing on SN 2 transmissions, a
point that was noted by crews with some consternation.
A.D.I.(K) and S.D. Felkin
U.S. Air Interrogation. Wing Commander
27th January 1945"