Main battery and underwater protection for Battleships

The following is a translated summary of an article in Marine Rundschau 23 1912, a reprint of Engineer Salvatore Orlando's article in Revista Maritima from 11th November 1911.

Tactical considerations are generally the decisive reason for placement of the artillery. The ship designer has to take into account the entire organism of the ship and the armament has to be designed in such a way it can account for the tactical schools to follow. The artillery must predominantly be able to fire over both sides laterally for a classic broadside. However despite this the battery must attempt to prevent large sectors of longitudinal fire with poor effect.

None of these designs adhere to the design principles. Design A has no capability for a full broadside. Design B has poor angles of maximum fire at roughly 90° per side. Design C does have a good 130° sector of fire but has a stem and stern coverage sector of 50° with only a single turret. This can theoretically be brought to 140°/40° respectively but that requires significant extension of the ship and the removal of superstructures. 

When looking at superfiring lay-outs one finds these designs do adhere to the design principles. If a turret beyond the 4th is added then it would not employ its greatest potential due to limited coverage caused by two dead angles afore and astern. Therefore, improvement in firepower is preferably done by increasing the calibre of the artillery.
With 4 turrets of which 2 elevated, each of them has only one dead sector. If the turrets are placed close to each other the blind sector of the lower turret can reach 70° for twin turrets with 34,3 cm guns. This diminishes as the turrets are placed further apart. But can be limited by the need to keep the muzzles away so as to not injure the turret beneath. The minimum blind angle is roughly 60° for 34,3 cm guns. A bit more for triple turrets. The broadside angles can not exceed 120° this way.

The appended sketches illustrate four different methods of superfiring compositions. The first is the classic “Michigan” type. The rest attempts to make the bow-stern fire sectors more effective by moving the turrets to the side.

	Sum Dead Sectors	Sum Broadside	Sum Guns
A	460°	490°	1960°
B	332	554	2216
C	300	570	2280
D	220	610	2440
E	202	619	2476
F	180	630	2514
G	180	630	2520

When it comes to dead angles the superfiring turrets are a clear winner over turrets on the same deck. When looking at the number of guns capable of firing to one side of the ship we can see the same trend. Which can also be seen when we look at the total sum of gun angles.

For fire directly for or aft, the group ABC has only a single turret operational whereas the superfiring layouts of DEFG have two to three. Under those conditions ships of the A, B and especially the C type are unable to effectively engage in a chase or retreating engagement. They thus must angle their profile to half the dead angle, between 6° and 25° degrees, to then be able to use two turrets. Meanwhile the DEFG group is not required to and can exploit two or even three of theirs.

The resulting difference in angles means the difference in speed would thus be V(new) = cos(25) ✕ V(old) = 0,90 V(old). This means a speed difference of around 2½ knots.

The ability to utilise both firepower and speed lead to the same result. Ships with superfiring turrets are preferred to those with turrets on the same level. A principle which the author has mentioned since 1907 and tried to prove was the best for the Italian navy.

	2-turret sector	4-turret sector
D	50°	120°
E	19	98
F	18	108
G	30	120

In regards to which of the superfiring layouts is preferable, if we check the sectors at which only two turrets can fire we see that scheme E and F have the smallest sector. This means that should one turret be knocked out they would have to provide the minimal course shift to bring fire to bear.

If we look at the 4-turret broadside sector D and G are the superior options. The sectors of E F and G could be enlarged should the dead sector of the turrets be kept smaller than 60°. D and especially G are preferred for the broadside, but E and especially F are only slightly inferior. Considering the better extremity sectors this version comes closer to the ideal characteristics.

Underwater protection
There has been a special emphasis on underwater protection since the Russo-Japanese war. Initial attempts of a double or even triple bottom and the armouring of the hull have proved ineffective. It is generally accepted that the armour has to be at least 5 metres away to reduce pressure. Consequently the longitudinal bulkhead is armoured these days.

However, the armouring of this bulkhead has proved vulnerable due to its great height. They often get bent in such a way they tear off at the connection points at the armour deck and double bottom. They have to be thusly designed to: 1) have the lowest possible height to allow the greatest possible resistance; and 2) If it breaks the water that penetrates up to swimming level cannot cause significant transverse movements.

It is known that the armoured deck is most resilient to underwater explosions. The most vivid effect is in the horizontal plane. When tests were carried out the armoured deck withstood explosions that destroyed the bulkheads over a wide area.

By lowering the armoured deck one can lower the height of the bulkheads and furthermore reduce the effects of flooding on the buoyancy.

In a ship with the following parameters:

Length PP: 156,28 m
Length CWL: 165,28 m
Widest beam: 27,80 m
Depth: 7,95 m
Displacement: 21 000t
Height of deplacement origin of mass: 4,50 m
M.F. : 7,00 m

In this example, the height of the bulkhead in the original design is 7,45 m in the middle and 5,65 m at the stern whereas with the new designed underwater protection the heights are 4,5 m and 2,70 m respectively. The new armoured deck would provide better stiffening to the armoured belt and would cause a weight reduction of 190 t in the example given.

Revolver Dreadnought

The following bulletin is a translation from Marineblad, 26th year 1911 / 1912, number 10 and Marine Rundschau 23th year February 1912.

M. Lorenzo d’Adda, his most eminent Italian engineer, has already on several occasions published in Moniteur de la Flotte his visions for the construction of battleships. He is known to be a supporter of displacement reduction and a hearty proponent of revolver turrets.

 

(image: Marine Rundschau)

Here are the particulars and sketch of a battleship of this engineer’s hand.
Displacement: 16.000 ton, Length: 150 meter, Beam: 25 meter.
Armament: 12 cannons 30,5 cm L46, 16 cannons 12 cm L50.
Protection: 30 cm belt, 20 cm sides, 30 cm turrets, 20 cm casemates.
Motors for 6 shafts, 12 cylinders for each shaft thus 72 cylinders of 333 HP per cylinder or 24.000 HP total.
Speed 22 knots.

(image: Marineblad)

Weights:
6400 ton 40% hull
3100 ton 19,2% armament
3900 ton 24,4% armour
1600 ton 10% motors
1000 ton 6,3% oil
16000 ton total.

Radar - Part Three: NV Hazemeijer Signaal-Apparaten and exile

On the 1st of October 1935 the Koninklijke Marine appointed Schagen van Leeuwen to assistant of the direction NV Hazemeijer Signaal-Apparaten. Before the outbreak of the war he had asked to not cut off his telephone line, but on that fateful morning the demolition parties had done so anyway. After cycling to the police station he came in contact with the colonel. The colonel had ordered his troops behind the IJssellinie. “In 10 minutes the Germans are at you. I cannot help you further. Be well.”
    Schagen van Leeuwen hastened to the train station to potentially prepare a train with important materials and devices. However, all trains had already departed. Soon after motorised troops arrived and occupied the station and soon after an armoured train joined them. Arriving back home he had found his own staff, amongst them H.C. Ackermann, Engineer Buitenhuis, Kuyvenhoven and a number of army NCOs. It was decided to head west with the greatest haste and thus the party embarked on their bicycles in the early morning.
    The original plan was to traverse the IJssel at Zwolle, but after circumstantial observations they directed to Zwartsluis. After seeing Zwartsluis occupied they moved further and late in the evening arrived at Vollenhove. With the help of the mayor a boat was arranged to direct them to Hardewijk. After arriving in the early morning Hardewijk was deserted from all transport and after some bicker transport to Edam was arranged.
    
After taking some various detours in Amsterdam, Haarlem and den Haag the group arrived on the evening of 13th of May at den Helder in order to secure passage to England and continue the war effort. Aside from the Hazemeijer quadruplet they were joined by v. Adrichem Boogaert, van Haaften, Pröpper, O. de Booy et al. At den Helder H. Jolles welcomed the group from den Haag, but had the unfortunate news that no transport was available. The group was joined by a few more officers, amongst them Houtsmuller and Harmsen. De Booy remembered that de Rijkswerf had a fast open torpedo chase boat.
    The crew departed after midnight along with 6 ton of material. S. A. l’Honoré Naber was in charge of fort Harsens and under orders to fire at any unannounced arrivals or departures. But fortunately after hearing about an escaping torpedo chaser he deviated from assignment and did not give orders to fire. At daybreak the crew was picked up by a British Coast Guard trawler and arrived safely in Great Yarmouth.

After a demonstration by Willem van der Zaan and her 40 mm AA battery Vickers-Armstrong was tasked to deliver 200 complete assemblies as soon as possible. With the establishment of the Koninklijke Marine headquarters in London a task was sent to Marine Etablissement Soerabaja to deliver copies of the 40 mm blueprint microfilms. Schagen van Leeuwen was closely involved with this project. He had advised against making complete copies, as there were a number of teething issues. The British refused any of the suggested changes, which would naturally give them complications later on. However, a single change was implemented. Namely the replacement of the stereoscopic rangefinder with a radar-set.[note 1]

Naval Ordnance in Bath and Naval Research in Teddington were annoyed that Vickers was tasked with a project neither from their or Vickers’ origin. Resistance against the 200 assemblies was inhibitory and thus through Naval Ordnance a request was put forward for tandem projects. Kuyvenhoven was tasked with some assistance of Schagen van Leeuwen to help the Vickers Armstrong design bureau develop the “Buster”.
    Meanwhile, Naval Ordnance started their own project for “Staag” to outshine the “Buster”. When the design was finished they started a demonstration in Portsmouth in front of hundreds of authorities and experts. Results were unanimously disappointing. A draughtsman from Bath told Schagen van Leeuwen “It seems the safests place for an aircraft is in the air, sir!” In a debriefing Schagen van Leeuwen called it the worst AA gun he had seen.
The “Buster” embodying the Dutch and Schagen van Leeuwen’s ideas did find success under Kuyvenhoven and the mock-up received approval from the British Royal Navy. Two proto types were ordered from the Vickers-Armstrong factory at Dagenham. However, the bickering of Department of Naval Ordnance and the Admiralty Research has triumphed and the “Buster” was shelved.[note 2]

During the brief moment Kuyvenhoven was free from Teddington and Dagenheim, he and Ackerman searched tirelessly in patent offices through German files for an improvement in the stabilisation of the top. A solution was found in a mercury switch and after tireless work the assembly was made completely independent of the gyro compass.

(image: Hazemeijer №4 Mount aboard Van Kinsbergen, Collection NIMH 2158_014041)

It was not just the British Royal Navy that received the 40 mm Bofors from the Netherlands. J.E. Meyer Ranneft received word from Captain Blandy that the Americans had trouble with their 2.1-inch gun. Blandy wanted to see it in action and arrived at Trinidad where on the 20th of August the Tusacola and van Kinsbergen demonstrated the gun. Meyer Ranneft managed to get a complete set of micro films for the United States.

Meanwhile, Weiler, Kuyvenhoven, Staal and Houtsmuller worked tirelessly on the Isaac Sweers. Creating what was known as the RDF 289 with ca. 22 km range. Staal had also developed radar jammers.

After these endeavours Staal travelled to Ceylon to install various air warning radars. Followed by installing IFF devices on Marine Luchtvaartdienst aircraft, as well as American search radars. However, those were not supplied with aerials so Staal designed and developed them on-site himself.
    Furthermore, he installed radars on the Hr Ms Soemba and Hr Ms Willem van der Zaan. This proved arduous as the Soemba was equipped with Dutch Hazmeijer fire control and a method of conversion from yards to metres had to be made, which was helped by a Swiss watchmaker in Bombay.
    In 1944 the Hr Ms Tromp was to be refitted in Sydney with modern radar material shipped from the United States. However, no generators were supplied and the Americans worked with 60 Hz Alternating Current whereas the Dutch worked with 50 Hz. A solution was found by using the old Direct Voltage generators from the searchlights and using a converter made by Australian General Electric Company. The company was scared of this idea, but the Australian technicians were duly impressed by the Hazemeijer switches and the system had worked splendidly throughout the war.

Whilst Staal was on his grand tour in the east, von Weiler et al. were joined by D. Smit, G.D.A. van Beek and Boddaert as well as later Engineer J.H. Wiersum, P.D.Kruyt and Engineer Slikkerveer. The whole department was moved from Portsmouth to Witney in July to form the Admiralty Signal Establishment. Whilst the British were mostly occupied with search radars, the Dutch specialised in artillery radar. Here the group of von Weiler did a lot of work, but particularly they designed the 50cm radar with T/R switches, their antennae, radar linkage and synchronisation, moving target indication and anti-jamming devices. He had also worked on solving the issues of the 3cm radar which allowed the Canadian production to commence.

(image: sketch after BUSTER plans held at Tyne and Wear archives)

[note 1]: it seems originally the RDF type 262 was conceived to be used but this was too heavy. (Friedman, N., Naval Anti Aircraft Guns & Gunnery chapter 8 note 49.) It was further hoped to create the CRS 1 (Close Range System) director. This project was cancelled and instead development from the STAAG was repurposed into the CRBFD (Close Range Blind Fire Director) (Friedman, N., Naval Anti Aircraft Guns & Gunnery chapter 8 sub Fire Control)
[note 2]: of 102 assemblies ordered, only one system was delivered in the last quarter of 1947. (Moore, G., The ‘Weapon’ and Gallant Class Destroyers, Warship 2000-2001.

Sources:
Bezemer, K.W.L., Verdreven doch niet verslagen
Staal, M., Hoe de radar naar Hengelo Kwam
Ir. Kasper, R.A., Professor von Weiler, oprichter van het Laboratorium voor Elektronische Ontwikkelingen, LEOK Jubileumboek 1975
NIMH 092 Marinemonografie, 2.8 De bewegingen en akties van Hr.Ms. Isaac Sweers. Appendix 1: Bijdrage van de Koninklijke Marine in de technische vervolmaking van de geallieerde scheepsartillerie en vuurleiding - compiled by Ackerman June 1956 - and Appendix 2: Ervaringen in Engeland tijdens de laatste wereldoorlog van een groep radarspecialisten.

Images:
NIMH Collection 2158_014041
Tyne and Wear Archives DS.VA /6/PL/140 - BUSTER mounting
 

Lyon

Just a drawing of the Lyon-class battleship I found in the German archives. Enjoy :)

 

Source: RM 3/23509 pg. 27

https://invenio.bundesarchiv.de/invenio/direktlink/9dd9f440-134a-4c5e-9407-1ce442b759d9/

Rocketry in the Koninklijke Marine

The following are (summaries of) translated pieces regarding the equipage of warships with rocket weaponry, 1947-1948.

From: Chef Marinestaf (CMS)
To: Vlagofficier Materieel (VOM)

In response to the note sent to me by the head of the Armament Subdivision, I have the honour to inform your Most Honourable Lord the following.

1 - I have read the matter discussed in the memorandum with great interest and fully agree with the opinion of the Head of Armament that it is necessary to follow the expirations and maintain close contact with the Oerlikon company.

2 - Both in the United States and England, and very probably also in Russia, the development of guided missiles - as you know - is being worked on with great speed. According to the press, several favourable results have already been achieved.

3 - As far as I am currently aware, these results are not yet of such a nature that ships will be equipped with "guided missile arrays".

4 - However, in my opinion it is by no means a stretch to assume now that in a few years' time warships will be equipped with guided missiles, either against air or against sea targets or against both.

5 - It is understandable that these weapons will require special training for the personnel responsible for their use. The Americans have already decided to create a special service area for "guided missiles".

6 - However, it seems to me that this - in typical American fashion - has gone a bit too far.

7 - A closer look at the guided missile, with everything that goes with it, shows that the targeting and control devices are essentially the same as the targeting and radio or radar transmitting devices already present on ships. The setup itself is a lot simpler than the artillery setups currently in use, so that only the actual guided projectile is something completely new.

8 - If, as the memorandum from the Chief of Armaments already indicates, these projectiles are stored on board as ammunition, the problem does not seem complicated from the user's point of view.

9 - However, special training will prove to be very necessary for the technical staff who will be responsible for maintenance and repairs

10 - It is still difficult to predict whether we will be able to benefit from this if the Americans and/or the British were to arm their warships with guided missiles. Presumably this will certainly not be the case, at least in the beginning.

11 - It is therefore a gratifying fact that Europe is also working hard to solve this problem and, where it appears, with a good chance of success.

12 - Since, as already explained in point 4, arming warships with guided missiles can be expected with certainty in the, perhaps near, future, we have a duty to remain extremely diligent in this matter.

13 - Due to numerous unknown factors and the limited knowledge we currently have about this new weapon, it is currently premature to draw any conclusions from the Chief of Armament's memorandum regarding the application of the new weapon on ships.

14 - However, I imagine that it would be desirable, as soon as more information regarding the Oerlikon guided missile arrives, to appoint a committee of several officers by mutual agreement. This committee should be instructed to conduct a study of the design of the missile, its uses and provisions that would have to be made for the training of personnel if the Koninklijke Marine were to introduce guided missiles.

15 - I request you to inform me whether you agree with the suggestions contained in this note and furthermore whether and when more information regarding the Oerlikon projectile can be expected.

signed, Vice Admiral Chef of the Marinestaf, Jhr. E.J. van Holthe.

 

 

Radar - Part Two: Philips

The following is a translated summary about an article regarding the Philips Obstacle Detector.

In 1935 Engineer C.H.J.A. Staal joined the team of Engineer K. Posthumus, inventor of the improved Dutch cavity magnetron, which operated at 40% efficiency and 50-cm wavelength. An improvement was made to 19 à 25cm at 10 Watt. Modulation frequency for the radar trials were set at 400 Hz. It was then a mission to find purposes for these inventions. Between Eindhoven and Tilburg and Eindhoven and and Nijmegen a link of 140cm and 25cm respectively were set up. Two wooden parabolae coated in metal paint were used for reflectors and a traversable metal plate of 1m² was used. The Koninklijke Marine was interested in these trials and perhaps inspired by the SS Normandie wanted to detect ships with this.

 

The antennae on the Stuifdijk, Marinevliegkamp De Mok

 

At airbase De Mok, Texel, on the stuifdijk (dust embankment) a pair of parabolae were placed in June-July 1937. Results were disappointing as constant reflections were measured. Attempts to solve this problem were in vain and in late August these tests were ended. In the discussions after the bad results van der Mark of the television group suggested using pulses. Staal supposed that the oversight of this in hindsight obvious solution was the result of tunnel vision and proved once more the value of bringing in outsiders to look at a project.

A local oscillator of around 1500 MHz (20cm) was used. For the display an oscilloscope, the A-scope, was used. The navy gave the team a wooden cabin at Wijk aan Zee and two cannons to use in tests. The parabolae were mounted on top of the barrels and tests in 1938 showed the ability to detect a 1 m² plate at 1000 m. A Z-class torpedo boat was then detected at 3000 m.
Based on the promising results a test installation was ordered and installed in the first two months of 1940 at around 1½ km north of Wijk aan Zee. Two tests were scheduled of which the former on the 6th of March with an auxiliary minesweeper failed due to communication failures. The second, on 20th March, the tests with Jan van Brakel succeeded with echos being visible up to 3200 m. A test with Sumatra was considered.

The current model used only one parabola separated by a horizontal bulkhead. This model was shown to two French officers in May 1939. Back in the NatLab of Philips a new model was being developed. This one mounted on a searchlight mount to allow vertical elevation. In March-April this one was ready. However due to dissatisfaction with the performance of the magnetron a new model from May 1940, the HF dubbeltriode DZ 19, was used. Which increased the wavelength back to 40cm.
Due to the high demand for altitude meters the development of the obstacle-detector was put off until October 1940 when the demobilised engineer Zonneveld was tasked with the resumption. In the summer of 1941 new tests were held on the roof of the factory in Strijp, under the eyes of an alert but unaware German soldier of the air warning service.

'Radar: een vergeten stuk geschiedenis'. Ongepubliceerd artikel van ir. R. van der Hulst en prof.ir. E. Goldbohm over de ontwikkeling van de radar bij de NV Philips' Gloeilampenfabrieken te Eindhoven vóór de Tweede Wereldoorlog. Met marginaal commentaar van Erik de Vries.

Nationaal Archief, Den Haag, E.K. de Vries, nummer toegang 2.21.327, inventarisnummer 264

Mc Kechnie Gas Dreadnought

The following bulletin is a translation from Marineblad, 22th year 1907 / 1908, number 4.

J Mc Kechnie, director of the steam sector at Vickers, held a speech at the convention “Institute of Naval Architects”, about combustion engines as primary engines aboard ships.

His primary argument was that the large funnels could be dropped, giving more space amidships for mounting large guns. Furthermore, the weight savings allow for more heavy guns to be placed. The judgement of the feasibility of combustion propelled ships he oughted as probable. He designed a ship of the line of 16000 ton. The layout of the gas engines is in 3 sections. The 4 shafts are each driven by a 10 cylinder vertical gas engine. The gas generators are divided into two compartments. The last section is in the foremost section containing 4 sets of air pressure pumps.

A table is provided with the primary advantages.

	Steam Engine	Gasmotor Engine	Liquid Fueled Motors
I.P.K.	16 000	16 000	16 000
Machinery weight	1585 ton	1105 ton	750 ton
IPK / ton	10,1	14,48	21,33
Occupied space	7250 square feet	5850 square feet	1110 square feet
Fuel per hour per IPK at full power	0,7 kg	0,45 kg	0,3 kg
idem, ¼ power	0,75 kg	0,5 kg	0,35 kg

Further advantages considered are the better protection of munition against heat and the lower temperatures in the machinery rooms.
Another design was provided of a torpedo boat destroyer with liquid fueled combustion engines.

In the discussions, Sir W. White asked how many IHP the largest as of yet built combustion engine could produce. Receiving the answer of 800 IHP, Sir W. White called the design of 16000 IHP a sport design.

Source: Marineblad jrg 22, 1907/1908 [volgno 4]. Geraadpleegd op Delpher, https://resolver.kb.nl/resolve?urn=dts:2305004:mpeg21:0001

Model of a Battleship for the Koninklijke Marine

The following is a translation from an article found in two magazines from 1946.

Image: Onze Vloot March 1946

Now that the airweapon provides speed this factor is no longer needed for battleships. Thus the ship can be shorter, needs less machinery weight and required boilers and less length to armour. The armour isn't very thick because current heavy projectiles penetrate everything anyway. But to ward against light projectiles and to localise explosions a lot of light armour has been applied. The rocketbomb guided by radio is new. The machinery is in an unorthodox position, namely high up, to protect them against mines and torpedoes. Consequently the screws can't be driven directly, but are driven by electric motors. In the machinery room are dynamos to provide the necessary power.

The ship is expected to be for the indies in a "United Nations" fleet. Hence the main battery is conservative. The ship is foremost a vessel to transport the main battery. For aircraft and torpedoes are other ships in mind. The medium calibre 12 cm AA guns are chosen for their ability to work against destroyers and motortorpedoboats.

Information:
33.000 ton, 28.400 ton washington.
L,B,H,D, 216m/30m/13,60m/8,80m
66.000 SHP, 25 kts.
6 - 38 cm, 32 - 12 cm, 36 - 2 cm, 1 guided rocket tower.

Armour is not specified except for the 300mm belt and the 30mm bottom armour.

Source: Onze Vloot March 1946, Schip en Werf October 1946

Radar - Part One: Meetgebouw & Commissie Physische Strijdmidellen

Around 1924 the news of a rumoured death ray expanded throughout the press. This caught the attention of many including the Dutch government. Whilst this did not prompt any significant research in a death ray it did highlight an apparent lack of investment into physics. Consequently this formed the birth of the Commissie Physische Strijdmidellen, which soon had its own laboratorium at Waalsdorp.

Around 1933 the acoustic listening devices proved insufficient for the rapidly advancing technology and speeds of aircraft. An attempt was made to use passive electromagnetic detection. A superregenerative receiver for wavelengths 3 - 10 m was built which could detect aircraft at 10 km. However this swiftly ended as engines were shielded and a shift took place to diesel fuel.

An attempt to develop an IFF transmitter was also made. The project started in 1934 and took off in 1938 but trial and fabrication did not proceed. A different tangent with the radar did start in 1939 and would be tested on the 10th of May 1940, the day of the German invasion.

During trials with ultra short wavelength radio an interesting phenomenon occurred. Interference took place and this was attributed to the crows and gulls near the testing site. Von Weiler, who led these tests, swiftly realised the potential in detection. Furthermore by using pulses a method of rangefinding could be developed. For logistical reasons the wavelength 425 MHz = 70 cm was used. The transmitter had a max power of 1kW. The antenna was rather large as it was a 3 by 3 meter square mattress containing 64 parallel coupled dipoles. The transmitted beam had a conical shape of 15 degrees and the received signal was both audible and along with a cathode-ray (J-scope) display.

Image: The antenna matress, from Friedman, N., Naval Radar

Fabrication of the “Electric Listening Device” M39 started in 1939 with 10 prototypes being ordered. Tests showed that a Fokker C. V could be detected at 15 km at 15 KHz and aircraft groups at 30 km at 7,5 KHz. The Navy also seemed interested in a model for the cruiser Sumatra, preferably with a 15 cm wavelength model. A heightfinder could be produced by creating a vertically stacked model.

Of the 4 models ready one was mounted at the Maliebaan, The Hague. Another was mounted at the deer camp. One atop the laboratorium was destroyed. Max Staal [note 1], who was in north Drenthe at the time, rushed back on his motorcycle through the afsluitdijk. After his brief stay in The Hague he departed along with Von Weiler to Scheveningen where they left aboard HMS Malcolm. Engineer Piket managed to sneak two models with him through IJmuiden and then arrived at Portsmouth.[note 2]

Von Weiler and Staal reached HM Signaal school. During debriefings the English were surprised that the Dutch developed radar, not the least one which was more modern especially in the field of pulse technology and the use of a signal antenna. However, the Dutch model came with a significantly weaker magnetron. Another oversight by the Dutch was that the maximum power output of a short pulse could exceed the constant maximum of the transmitter tube allowed.
Von Weiler and Staal cannibalised one of the two models and placed the other aboard Hr. Ms. Isaac sweers. The ship received the 40mm Bofors Hazemeijer mounts from Willem van der Zaan and together with British Yagi-Antennae she received what became known as RDF 289.

 

Image: RDF 289 aboard Hr Ms Isaac Sweers, Museum Waalsdorp website

 

 

Image: 40mm AA mount with RDF 289 Yagis on Hr Ms Isaac Sweers, Collection NIMH_2158_005294

[note 1]: Engineer M. Staal placed at the Commissie Physische Strijdmiddelen in 1939 was different from Engineer C.H.J.A. Staal at philips.
[note 2]: Only 4 were produced but I found 5 different ‘sightings’ of the radar and an known ultimate fate of 3 models.

Sources:
Cruijff, H., Hr. Ms. Isaac Sweers en de ‘Hollandse Radar’
Staal, M., Hoe de Radar naar Hengelo Kwam
1927 - 1977 Physisch Laboratorium TNO
1975 LEOK Jubileum boek
The Electric listening device (1936 – 1941), Museum Waalsdorp at https://www.museumwaalsdorp.nl/en/museum-waalsdorp-2/5547-2/radar-electric-listening-device-1936-1941/

Welcome

Hello and welcome to this newly established blog.

As a quick introduction, I go by Sanglune on the internet. I’m an enthusiast for military equipment and strategy. After having delved up plenty of knowledge from various archives mostly pertaining Dutch Naval development and politics I decided that the best course of action was to share it in proper concentrated format. Since not every piece of information suits the same format I figured a blog would be the best way to create/share bulletins and articles.

Most initial content will be about the various discoveries regarding Dutch Naval developments around the first half of the 20th century, as that is where my expertise lies. Though that does not mean I will skip out on everything foreign. There may also be some branching out in the future regarding the covered material types, such as aircraft, armour or general artillery matters. Alternatively I may invite guest writers. But that is a future concern. For now I bid you welcome. Please enjoy your stay.

Yours truly,
Sanglune