The Schornsteinfeger Project

C.I.O.S Report XXVI-24

May 1945


Reported by Sq./Ldr. G.G. Macfarlane

C.I.O.S Target Number 1/549 Radar


The essential pages of the joined Allied investigation report on German naval Stealth technology

The Germans used several code-names for making their U-boats and other vehicles less visible to radar signals, like: Sumpf  and Schornsteinfeger and for aircraft: Schwarzes Flugzeug (Black aircraft)

It is understandable, that the Allied Intelligence whould like to know about the German scientic approach in this field.

That the content of this report must have been of (some)significance is evident, as this report was finally declassified on 26 April 1960, thus, say, fifteen years after Germany had surrendered in May 1945.

When one read other CIOS or BIOS reports, originating from those post war days, the impression is often given, that the (British) investigators did not like the German approach and their results. From the British side the factor "being not invented here", might have played a role!


Members of this team were:

Lt. Cdr. Harvey Hall (USNR); Lt.(jg) Paul W. Wilkinson (USNR); Lt. (jg) Clifford E. Young (USNR); Cdr. John P.L. Vigoureux (RNVR); Lt. Cdr. Emil N. Rowland (RNVR); Lt. Arthor S.L. Rocke (RNVR); Sq./Ldr. John C.E. Jennings (RAF) and the trip No. 89 leader: Sq./Ldr. George G. Macfarlane (RAF)

English language (PDF 1 MB)



This photograph is shown in the way as it was originally taken



Both photos originate from U889, which surrendered to the Canadian Navy in May 1945, at Nova Scotia. The shape of the stealth layer, attached to the Schnorchel is quite good visible. The circular antenna is code-named Bali, and covered the obsolete ASV- band operating at about 200 MHz. Most systems where already replaced by S- or X-band radars around mid 1943. The deployment of Bali antennae was very counter productive, because what was gained by the absorbing "Schornsteinfeger or Sumpf" layer was being lost by this well reflecting antenna device. (Consider for further details this CIOS Reprort)


Keywords: Historical background a OKM Conference June 1943; four main lines of developments; Marine Baurat Kühnholt (OKM Wolfenbüttel); Küpfmüller; Netzhemd; Becker-Hellwege Absorber; Jaumann-Absorber; Wesch-Absorber; Becker-Hellwege type absorber was studied by DEGUSSA ..; OKM 1944; Jaumann-Absorber was first to be put into operational use about September 1944, was developed theoretically by Prof. Johannes Jaumann of Bruenn (Brünn?), the actual development was centralized under contract with OKM at the I.G.Farben factory in Hoechst, near Frankfurt, where Prof. Jaumann acted in the advisory capacity.... Dr. Kiesskalt ..; Dr. Brennscheide .. Dr. Rathscheck; Kiel connection .. ; Berlin Conference of June 1944; igelit; cellular igelit = pvc ...; igelit was made by the firm Record in Schwiebus for use in bullet-proof tires ..; Schnorchel consist of ..; surface capacity, German Snooper units ... ; Buna containing iron .. ;Kugelschwimmer . The Wesch absorber is more selective than the Jaumann type, being most effective for S and X band frequencies ... ; Product data .; Heep ; total numbers of Jaumann-Absorbers which had been fitted between November 1944 when production began and March 1945 when production disrupted by Allied action is estimated to be just less than 100 .... ; The total numbers of U-boats fitted was stated by Dr. Kiesskalt to be about 60 ... the average time interval between production and final testing after installation was said to be 4 - 5 weeks. Rejects at Kiel averaged 30% in October (1944) and only 2 % in March 1945 ... ; cellular igelit Troisdorf .. conducting paper Okriftel  - glues at Leverkusen Hoechst for testing I.G. Farben Neustadt assembling semi-cylinders .. Navy yard Kiel ..; Wesch-Absorber ..; I.G. Ludwigshafen-Oppau(?) Dr. Ambros-Herbeck-Jordan-Berger-Weber and Enigneer Klant .. performance .. ; Oppanol-0 ..; Welt Post Institute Heidelberg Theoretical work - Philip Lenard Institute samples - I.G.Farben (Freudenberg), Weinheim (shadow factory of Oppau fabrication - I.G. Leverkusen - Perbunan .. ; Wesch-Mats .. ; Jaumann semi conducting sheets (layers) .. ; Electrical Properties and Theory .. ; Surface resistance .. ; Equivalent circuit of Jaumann Absorber transmission line Admittance; Fig. 3 locus of input admittance at 00 normalised to wave admittance in cellular igelit ..; Theory indicates .. ; theoretical performance of Jaumann Absorber ...; properties of materials - cellular igelit pure pvc without additives known in USA and UK as Therazote .. ; Cellular igelit was produced by Dynamit Nobel A.G. originally in Troisdorf later at a shadow factory in Eilenburg Saxony after Troisdorf was bombed .. ; Buna-S3 - recently a new kind of gamma iron oxyde been produced having K = µ = 5 process invented by Dr. Huettich (Hüttich?) of Prague .. ; construction of the Wesch-Absorber ... ; chloropren; equivalent line circuit of Wesch-Absorber ..; spacing layer is made of Oppanol which has constant of 2 and loss angle of ... 



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