Performance modifications done at Squadron level. (7 Viewers)

[Buz101]

As stated above it had a lot to do with the change of radio. I know other radio types existed but I'll keep it between the 274 and 522 sets as it'll make more sense (much better than a full history of radio sets in P-40's, needs a book in its own right)

SCR-274N was the earlier radio and covered 3.0-9.1mc (HF bands) and 100-156mc (VHF bands), had a range of approx. 75 miles for Voice (let's not go into the variables but say max range) - and could give Carrier Wave, Tone and Voice. Now being a HF and VHF set, it needed some decent length antenna for the HF side of the house, hence the long cables to the wingtips.

It was replaced by the SCR-522A which operated solely on the 100-156mc (VHF band) and gave a voice range of (again max) 130 miles and came with the AN-104-AX antenna mast.

From the P-40 point of view (will not vouch for any other airframe type), you start to see the antenna appear around the P-40F-5 (the earliest image I have is of 41-14305 with one, the latest P-40F I have is 41-14248 which does not - so gives a reasonable timeframe of late Aug/Sep 1942). Quick review shows early K's without yet later K's with so timeframe looks good.

Now for the biggest caveat, just because they left the factory, or where delivered fitted with the SCR-522 and the mast, doesn't mean they kept the 522, and would often be converted back to the SCN-274N, especially in Pacific where the operational ranges were greater, so a requirement for HF still existed. I've seen P-40F-15 based in the Central Pacific without masts (44FS and 68FS), seen RAAF late model K's (77SQN) without masts, P-40M's of both the USAAF (44FS) and RAAF (76SN) without masts (in fact check out SV-E in this photo, not seeing a mast on that one). I'm sure if we looked at images from various theatres of operations (once the SCR-522 came into operations) we can see the differences, with places like the Aleutians and CENTPAC using HF due to ranges, SWPA the same until the hoping started in earnest, then more VHF radios in use, Italy mostly VHF etc. That said I've not see a P-40N in the Aleutians without a mast.......

Now just to make the waters even muddier - I've seen earlier aircraft fitted with the AN-104-AX later in service life (such as 41-13601 fitted with one), so it really pays to have a photo of the aircraft concerned (for the modellers out there).

I thought Ns were out much earlier than that..? more like mid 1943

As per Geoffreys list - Acceptance dates 15th Mar 43 and 17th Mar 43 for the first two, then the remainder from 24th Mar 43 onwards

Buz

 

[Steamed_Banana]

To complicate things even more I think (?) the British put in their own radios in North Africa? Anyway I remember reading in different pilot memoirs about two radio sets being used on some British kittyhawks, one presumably short range (HF?) for the squadron and another long range set for the commanders to talk to the base. There were complaints about some planes having an HF and some having a VHF set, I remember mention of one type having buttons which made it much quicker and easier to change channels, whereas the older type had a knob and sometimes guys died trying to find the squadron channel or switch channels ... and didn't hear warnings in time. Not sure if the Soviets put in their own radios. I'd assume the Australians and N-Zeds used US radios in the Pacific. Also not sure about the Canadians and Dutch.

I'd really love to learn a bit more about the Dutch operating in the Pacific late in the war, I have seen photos of P-40s and other aircraft with Dutch markings, or was that after the war?

 

[EwenS]

I'd really love to learn a bit more about the Dutch operating in the Pacific late in the war, I have seen photos of P-40s and other aircraft with Dutch markings, or was that after the war?

Main units were 18 NEI squadron (formed April 1942) flying B-25D/J alongside 2 RAAF squadron out of bases in the Northern Territory around Darwin and 120 NEI squadron (formed Dec 1943) that flew P-40E/N in New Guinea. 120 would have transitioned to the P-51D had the war continued. Histories can be found here:-

Netherlands East Indies Air Force in Australia during WW2

No. 18 (Netherlands East Indies) Squadron RAAF - Wikipedia

en.wikipedia.org

No. 120 (Netherlands East Indies) Squadron RAAF - Wikipedia

en.wikipedia.org

There was also 321 (Netherlands) squadron RAF flying Catalinas, augmented from Dec 1944 by a flight of B-24 Liberator VI, from the base at China Bay, Ceylon from Aug 1942. It formed from a core of 4 Dutch Catalinas that escaped from the DEI in March 1942. They had a detachment of Liberators operating from the Cocos Islands in the Indian Ocean, SW of Java from the beginning of July 1945. The role was maritime recce.

Edit:- There is a series of books that cover individual types of Dutch aircraft including most of the types noted above.

Aviation Book Centre

Aviation and Military Book Shop shipping directly from the UK across the Globe. We have the latest Desert Eagle books and other must-have magazines and books for enthusiasts of all ages.

www.aviationbookcentre.com

 

[Steamed_Banana]

Anyway super interesting summary. Thanks Geoffrey and Buz. Radios are one of those things you don't think about too much but I suspect were far more important than superficial analysis suggests, and not just in the category of 'did they have one or not' but also in the details of how they worked. Even where one side had radios and the other didn't, getting the radios to work properly and effectively (which could be via a combination of training, doctrine, maintenance, and the quality of the radio - and maybe it's suitability for certain environments lets say, with harsher environments in the more tropical areas sometimes meaning less effective - meant that earlier in the war a lot of times the radios just weren't working. Gradually they seem to have worked out all of these factors over time, but it wasn't an overnight fix.

Another possibly related question - I notice some US and Aussie Kittyhawks in the Pacific and CBI had radio direction finders, either a loop or a sort of torpedo shaped thing on top, which makes a lot of sense given how often they got lost. But do you have any sense of when this started being done, and where, and whether it was a from the manufacturer type thing or a field modification? My sense is more the latter just because it seems like only some aircraft had these. Presumably they take a little hit from drag, same with a radio mast. Not sure about the wires to the wingtips.

 

[Steamed_Banana]

Main units were 18 NEI squadron (formed April 1942) flying B-25D/J alongside 2 RAAF squadron out of bases in the Northern Territory around Darwin and 120 NEI squadron (formed Dec 1943) that flew P-40E/N in New Guinea. 120 would have transitioned to the P-51D had the war continued. Histories can be found here:-

Netherlands East Indies Air Force in Australia during WW2

No. 18 (Netherlands East Indies) Squadron RAAF - Wikipedia

en.wikipedia.org

View attachment 860992

No. 120 (Netherlands East Indies) Squadron RAAF - Wikipedia

en.wikipedia.org

View attachment 860993





There was also 321 (Netherlands) squadron RAF flying Catalinas, augmented from Dec 1944 by a flight of B-24 Liberator VI, from the base at China Bay, Ceylon from Aug 1942. It formed from a core of 4 Dutch Catalinas that escaped from the DEI in March 1942. They had a detachment of Liberators operating from the Cocos Islands in the Indian Ocean, SW of Java from the beginning of July 1945. The role was maritime recce.

View attachment 860990

View attachment 860991

Edit:- There is a series of books that cover individual types of Dutch aircraft including most of the types noted above.

Aviation Book Centre

Aviation and Military Book Shop shipping directly from the UK across the Globe. We have the latest Desert Eagle books and other must-have magazines and books for enthusiasts of all ages.

www.aviationbookcentre.com

Super cool thanks! Got some reading to do here!

 

[ColFord]

February 1941. As an example, from No.26 Squadron RAF, Curtiss P-40 Tomahawks in the UK fitted with RAF specification radio sets. Various types of HF and VHF sets fitted depending on tasking and operational requirements. Also IFF fitted.

 

[Geoffrey Sinclair]

WWII was in many ways an electronics war and only the US had anything like the capacity needed. The communications fit for a B-29 costed in early 1943 was heading to $35,000, A complete P-39 $51,000, a P-40 $45,000. In 1940 the average British infantry division had 75 radios, most morse, versus nearly 1,000 in 1944 despite having around the same firepower. People think of the Panzer Division but everyone had those, and the Germans several versions in the 1939/40 period until experience showed what was best. After the abandonment of the Red Army deep battle ideas only the Germans had Panzer Corps, but also understood the need for faster decisions, to match the faster marching speeds. Hence encouraging initiative and using Enigma, accepting the extra risk of communications intercepts as the price for speed. It worked, the German Army spent most of WWII being able to create and implement actions faster than any opponent, which gave it a real edge. For the USSR in WWII the fact imported aircraft and tanks at least came with working radios was a major bonus, too often Germans had worked their way from back to front shooting down/knocking out their opponents who had no way of reporting to those in the front.

Radio was high tech cutting edge and experience was overwhelmingly from the temperate and toward polar areas of the northern hemisphere, that left big gaps in what worked elsewhere. Mid war the RAAF was the leading export in making cutting edge electronics work in the tropics, using the locally made Light Weight Air Warning Radars. The following is mostly concerned with longer distance communication but gives an idea of what had to happen to make things work reliably. For example to have direction finding required usually multiple ground stations able to transmit on frequencies that would propagate far enough, plus the electronics on board the aircraft.

An excerpt from a report, probably written in 1945.

THE OFFICIAL HISTORY OF THE R.A.A.F.
DIRECTORATE OF TELECOMMUNICATIONS AND RADAR
BY W/CDR, G. F. GATES

IONOSPHERIC ORGANISATION.

Radio communication, over all but relatively short distances, is effect by reflection of the waves by the ionosphere, or ionised layers in the upper atmosphere.

Radio waves penetrate, or are reflected by the different layers of the ionosphere according to their frequency, and the layers themselves vary in height with season, climate changes, and the sunspot cycle, so that the height of the relevant reflecting layer, combined with the angle of radiation, determines the angle of reflection and consequently the length of "hop" for any given transmitting frequency at a particular time. Further, from a study of ionospheric conditions, it is possible to submit either the optimum frequency or the maximum usable frequency for any given distance and time.

The R.A.A.F., at an early stage in the war, sought to promote extensive ionospheric studies, not only within the Service, but throughout Australia, and finally on the international plane. This policy was based on a statement made by the International Consultative Committee for Radio Communications (C.C.I.R.) in a report prepared by the Committee on Radio Wave Propagation in London on the 25th November, 1937. In this report, it ware made clear that then wore only two methods open for the specification of long distance transmissions-

(i) Derivation of accurate, but at that time, limited results based on normal incidence/equivalent height frequency curves of the ionosphere.
(ii) Use of extensive practical knowledge of the transmission of radio waves over the earth's surface for the construction of more comprehensive but less accurate charts of the ionosphere.

The R.A.A.F. chose the scientific path and having noted the statement that normal incidence as a survey of the results then available were inadequate ionosphere all over the earth and, having regard also to the Committee's conclusion that extensions of such measurements and prompt publication would be highly desirable, decided to take steps to foster such measurements and the speedy exchange of information which, it foresaw, was clearly necessary if its aim of maintaining communication 24 hours a day, 365 days of the year was to be realised. Had it not been for this action, it seems clear that the work of many physicists would have been shelved until after the war, and a valuable weapon thus lost.

In 1940, the Watheroo Magnetic Observatory of the Carnegie Institute was approached for assistance in the preparation of short-term predictions of maximum usable frequencies and reports of ionospheric disturbances. The Watheroo Magnetic Observatory co-operated fully in this matter. Shortly afterwards, a request was made to the Mount Stromlo Observatory, Canberra, for the supply of a daily report of ionospheric conditions. That service was commenced within a short time.

The records obtained at Canberra had been analysed by the Radio Research Board in Sydney for some years past, and the question of monthly predictions of maximum usable frequencies was taken up with the Board. It was agreed that the supply of additional ionospheric data was desirable, and curves prepared by the Sydney Laboratory have been published regularly since that time. At this stage, curves of maximum usable frequency were available only for the latitudes of 40°N and 30°S, and these had to suffice for all communications both in the Commonwealth and abroad.

It was laid down early in 1941 that R.A.A.F. Signals Officers were responsible for selecting correct frequencies for operations from those allotted, and that they must, at all times be familiar with the maximum skip distances expected on any given frequencies so as to obviate operational communication failures. However, it was soon found that conditions in tropical regions were not being satisfactorily predicted, and the need for additional data was indicated.

The Carnegie Institution of Washington agreed to send by cable monthly summaries of ionospheric data for Huancayo, Peru, at 12°S, and the Radio Research Board offered to calculate maximum usable frequencies from this data. Similarly, with the co-operation of the New Zealand Radio Research Board, use has been made of data obtained at Christchurch, New Zealand, at latitude 43°S.

By July, 1942, graphs of predicted maximum usable and optimum working frequencies were available for four latitudes: for Huancayo, Peru, latitude 12°02.7' South; Watheroo, latitude 30°19.1' South; Canberra, latitude, 35°19' South and Christchurch, New Zealand, latitude 43°35' South. The initial distribution of these graphs was 47 copies, of which 30 were distributed to R.A.A.F. units, the remainder being sent to other Services and overseas authorities. Watheroo Observatory supplied one set of predictions whilst the Radio Research (Sydney Section) supplied the remainder.

In September, 1942, graphs for each 10° of latitude for both Northern and Southern latitudes, from 40° North to 50° South, for October, were prepared by Radio Research Board and issued by the R.A.A.F. Only Southern hemisphere graphs from the Equator to 40° South were issued to operational units, but complete sets were issued to Government organisations, scientific and certain other bodies where full use of the graphs could be made.

This comprehensive service was made possibly only as a result of co-ordination of effort by the various centres of the Carnegie Institution, Washington; the Radio Research Boards, Sydney and New Zealand; the National Physical Laboratory and the Central Ionospheric Bureau, London, and the National Bureau of Standards, Washington. In this connection, the aim of the R.A.A.F. was to bring home to all concerned the need indicated above for speedy interchange of data and to demonstrate its operational importance by supplying, as far as lay within its power, the administrative machinery incidental to organisation on the international plane. Research physicists in this area of operations were thereby to be relieved of all detail likely to detract from the main purpose, that of providing up-to-date predictions of ionospheric conditions based on the most recent results of research throughout the world.

In the same month (September, 1942), the Department of Air convened an inonospheric conference in Sydney under the chairmanship of Sir John Madsen, as a result of which the Australian Radio Propagation Committee, consisting of representatives of the Services and Scientific Centres, was formed as a Committee of the Radio Research Board or the Council for Scientific and Industrial Research. (File No. 12/501/132) At the first meeting of this Committee, it was agreed that the R.A.A.F. should continue collection and distribution of ionospheric data, and that, in order to facilitate the handling of Service matters, the R.A.A.F representative should be Conjoint Secretary of the Committee. The 23rd meeting of the Committee was held in Melbourne on Tuesday, 20th March, 1945. Studies being undertaken by the Committee include -

(i) Tropospheric Propagation.
(ii) Ionospheric studies.
(iii) Preliminary Loran-Ionosphere observations in the Darwin area.
(iv) Noise level investigations - North Western Area. (Australia)
(v) Co-ordination of operating data regarding radio circuit performances and ionospheric data.
(vi) Development and production of Ionospheric recorders.

Because the monthly predictions only cater for transmission via the regular layers for average conditions, the R.A.A.F, in collaboration with the Watheroo Magnetic Observatory of the Carnegie Institution, inaugurated a short-term forecasting service. This was later extended to include a weekly signal predicting transmission conditions for the forthcoming week ending 2359 hours G.M.T. Friday. The R.A.A.F. based its assessments on magnetic data from Watheroo and Toolangi and reports of sun- spot activity from Commonwealth Solar Observatory, in additional to data available from Washington. On the formation of the Australian Radio Propagation Committee, the Commonwealth Solar Observatory became responsible for issuing forecasts of conditions for the Southwest Pacific Area. (Reference File No. 201/86/7) This forecast is issued each week to the R.A.A.F. for immediate distribution to the higher commands in this area for notification of all units under their control.

In December, 1943, the Australian Radio Propagation Committee decided to issue monthly bulletins of Ionospheric data to all the armed forces in the Southwest Pacific Area. It contained firstly, a Scientific Item telling something of ionospheric phenomena, how they were observed, measured, and upon which facts the monthly predictions and weekly forecasts are based; secondly, an Operational Item telling how to use the data and its application to communications in general; thirdly, an analysis of ionospheric conditions and short-period forecasts for the previous month but one. The aim was to increase all signals personnel's knowledge of the ionosphere since a practical understanding of the behaviour of the ionosphere with regard to radio waves would help to ensure the efficient selection and use of frequencies for communication purposes. These bulletins also provided a means of explaining to personnel in the field, the data as prepared by the Australian Radio Propagation Committee either in the form of graphs, contours or tables and the weekly and/or special forecast of radio transmission conditions.

However, during November, 1944, it became evident that for the data to have direct application to a particular service it was desirable that each Service issue its own bulletin. Therefore, in December, 1944, the R.A.A.F. issued its first Propagation Bulletin. The contents of the Bulletin now include an introduction and operational item, analysis of the Stromlo forecasts and complete sets of graphs of predicted maximum usable and optimum working frequencies from 70°N to 50°S. The operational items to April, 1945, have included three, items on "Loran and the Ionosphere" and the first of the series of articles on selection and performance of aerials. In addition to the monthly graphs, world contours and predicted maximum usable frequencies for distances 0 to 2500 miles in 500 mile intervals are also issued to certain units only since they are applicable only to multi-hop transmissions. In addition, it became increasingly evident that the link between the supply of Ionospheric data to units in the field, and the full application of such data was not complete, inasmuch as, whilst it was possible to predict suitable frequencies for various conditions of communication, it was obvious that insufficient consideration had been given to the selection of appropriate aerial systems. Efforts are now being made to associate more closely, the supply of Ionospheric data with the performance of the various types of radiating systems available in the R.A.A.F.

The seven chief uses made by the R.A.A.F, of the monthly graphs are -

(i) Allocation of correct frequencies for operations.

(ii) Deciding most suitable frequencies and time of change of channels to ensure reliable 24 hours communication on point-to-point circuits.

(iii) Laying down frequencies and hours of service for R.A.A.F. H/F C.R. D/F Stations which are situated at various latitudes throughout the Commonwealth. These time tables must be arranged in advance so as to avoid giving bearings when the transmitter is in skip distance from the D/F station.

(iv) Arranging intelligence interception watches to ensure that no time is wasted in searching frequencies higher than the maximum usable for any distance.

(v) Determining from skip distances given implicitly in the curves, the minimum probable distance of enemy transmissions.

(vi) Evaluation of bearings taken on enemy transmissions

(vii) Within the LORAN organisation in N.W.A. (North Western Area)

In connection with above sections (i) to (iii), an officer with two years experience in the use of ionospheric data, and in circuit analysis, is now located in that section responsible for frequency allocation, and is consulted in all matters pertaining thereto.

In 1942, it was decided that additional Ionospheric observing stations were required to provide additional propagation data to the Armed Forces and action was taken by the R.A.A.F. to procure three Ionospheric Recording stations for implementing facilities in Southwest Pacific Area, vide Air Board Agenda No 3842/42. Air Board Agenda 3842/42 proposed the purchase of three ionospheric Recorders from C.S.I.R. and Air Board minute dated 10th April, 1942, approved this proposal. This R.A.A.F. order for three was portion of an order for six placed through the Ministry of Munitions on C.S.I.R., of which two went to New Zealand and one to United States. (File No 201/16/757 Enclosures 2A, 3A & 5A.)

The equipment is of the equivalent height/multifrequency variety, and covers a frequency range from 1.0 to 13 Mc/s in 1 minute 55 seconds. It is an automatic recorder, that is, it switches itself on and off at appropriate times (every ten minutes), tunes its transmitter and receiver progressively from 1.0 to 13.0 Mc/s. and makes a photographic record of the heights from which any echoes within this frequency range are obtained. (Radiophysics Publication PD25/2 - "Handbook for Ionospheric
Recorder, Type J28".)

During 1943 it became evident that it was necessary to set up a long term plan to ensure the extension of communications as fighting areas move northwards from Australian and therefore it was decided by the Australian Radio Propagation Committee that Radiophysics Laboratory should build seven additional Ionospheric recorders of modern design and wide range. Of these seven, six go to pool, two for the R.A.A.F., two for the Army and two for the Navy, and the seventh is for the Commonwealth Solar Observatory, Mt. Stromlo. These recorders were to be built to the R.A.A.F. Specification Y.111.

In June, 1943, the Radio Research Board recorder at Brisbane commenced continuous operation and records are available from that date. The first R.A.A.F. recording station at Higgins, North Queensland, commenced operation late in November, 1944. Installations are under way at Momote (Admiralty Is.) and Stuart Creek near Townsville. (Reference File No. 201/23/443.) A further site is nearing completion at Hobart but the A.R.P.C. considers that Northern sites hold priority in the distribution of equipment. It is intended that one of the further seven recording sets being produced by Radiophysics will be installed at Hobart. From analysis of the records from Brisbane over the twelve months period and from early records from Higgins it has become evident that the frequency range will need to be increased and the new recorders are to be built to cover the range 1 to 16 Mc/s. instead of 1 to 13 Me/s.

In September, 1943, Radiophysics approached the Department of Air for the R.A.A.F to make available a suitable person to take over the information on Ionospheric Recorders and to assist with the installations. W/O. G.S. Johnston proceeded to Radiophysics and remained there for approximately nine months assisting in the development, assembly, and testing of the various units of the equipment. In October, 1944, after selecting a recorder site at Momote, W/O, Johnston proceeded to Higgins, Cape York, and supervised the installation and training of operators for the recorder there. Mr. A.J. Higgs of R.P.L. who was responsible for the design of the equipment proceeded to Higgins with R.A.A.F. approval for the calibration and final test of the recorder.

In September, 1943, it was decided that the development of a direct reading Ionospheric recorder was well within reach of practical achievement of the Radiophysics Laboratory and that such an equipment would be an invaluable adjunct to the Signals Organisation within the R.A.A.F. Approval of expenditure amounting to £3,000 for this initial equipment was granted in November, 1943. (File No. 134/2/36.)

In April, 1944, an International Radio Wave Propagation Conference was held in Washington. This was proceeded by a preliminary Ionospheric conference in London in March, 1944. The R.A.A.F. was represented at both of these conferences, by Squadron Leader A.L. Hall. (Report - "The International Radio Wave Propagation Conference, Washington, 1944" - by Squadron Leader A.L. Hall.)

With the opening of new long-haul circuits covering distances up to 3,000 miles it has become evident that frequencies higher than those anticipated can be used most efficiently. A considerable amount of study is being done on this work and it appears that over an area of Eastern and North-Eastern Australia reliable communication to say 80% of total time is being maintained by transmission via the Abnormal "E" layers. In this connection a preliminary report entitled "Occurence of Abnormal "E" Echoes at Cape York" by D.O. Stewart, No R.R.B. R/16 is to hand. (File No. 201/86/1.) As a result of these facts a proposal has been put forth that some type of mobile recorder should be made available to the R.A.A.F. in order that a more immediate complete picture of the Ionosphere over these areas can be obtained without waiting for the initial installation of our Ionospheric recorders in this area.

In accordance with the findings of the International Radio Wave Propagation Conference, Washington, April, 1944, it was decided that certain officers should be attached for a period up to ten days to the Sydney Laboratory or the Radio Research board for a period of intensive study and reading to enable them to have a more complete appreciation or the work being carried out in the field of Wave Propagation.

 

[MikeMeech]

To complicate things even more I think (?) the British put in their own radios in North Africa? Anyway I remember reading in different pilot memoirs about two radio sets being used on some British kittyhawks, one presumably short range (HF?) for the squadron and another long range set for the commanders to talk to the base. There were complaints about some planes having an HF and some having a VHF set, I remember mention of one type having buttons which made it much quicker and easier to change channels, whereas the older type had a knob and sometimes guys died trying to find the squadron channel or switch channels ... and didn't hear warnings in time. Not sure if the Soviets put in their own radios. I'd assume the Australians and N-Zeds used US radios in the Pacific. Also not sure about the Canadians and Dutch.

I'd really love to learn a bit more about the Dutch operating in the Pacific late in the war, I have seen photos of P-40s and other aircraft with Dutch markings, or was that after the war?

Hi
This doesn't quite make sense, VHF R/T has a longer range, clearer speech and easier tuning than HF R/T which is why aircraft were moving over to it during WW2. The SCR-522-A VHF set was based on the British TR1143 and was fully interchangeable with it.

On other matters P-40 the following document, an appendix in 'RAF The Middle East Campaign Volume III' from the AHB website so available as a free download. This is dated 11 July 1942:

Mike

 

[tomo pauk]

Thank you, Mike, this is amazing

 

[Buz101]

This doesn't quite make sense, VHF R/T has a longer range, clearer speech and easier tuning than HF R/T

Mike

Not quite sure that is correct, HF has a bunch of factors but depending on propagation (single and double hop), antenna set up, day time/night time, power, which layer (D/E/F (1/2)), what frequency etc etc etc can reach hundreds or even thousands of miles.......VHF is pretty much LoS. That said that VHF is normally significantly clearer and easier to tune (unless using button/pre tuned set ups (then they are the same).

Buz