FBG 2017 3 - WordPress.com turret was adopted. The 76 mm M1A1 gun in a T23 turret of the Sherman...

FBG News Forts & Bunkers Group

Edition 3 of 2017 Composed by Frank PHILIPPART

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WORLD WAR 1

Bunkers at Blankenberge protected

We have also some good news to report. Mr Kristof Jacobs reported to me that the two German bunkers of the airfield at Uitkerke near Blankenberge are now classified as a historical monument It took quite some time, because we sent the request to protect the bunkers on 19 Mar 2013. What’s it all about? It concerns two bunkers on either side of the Brugse Steenweg when you enter Uitkerke which is the small village before you enter Blankenberge.

The airfield was only built in 1917 with the intention to serve as a base for aerial observation for the surrounding coastal batteries. Two air force units were based here. One was the III Küstnfliegerstaffel Uitkerke of Küstenflieger Abteilung III.

The construction of the airfield of Uitkerke started in the beginning of 1917. The commander of the unit was Oblt.d.S.L. Schwarzlose with five HFT airplanes (HFT-unbewaffnete zweisitziges Flugzeug mit einem zwei-Wege-Radio). It’s an unarmed duel-seated airplane with a radio. The

command was passed to Lt.d.R. Paul Leffler on 19 March 1918 and in May of the same year, all the units of this airfield had six airplanes. In the night of Wednesday 6 October 1918 the unit left the

airfield to return to Germany. Unit IV Küstenflieger of Abteilung IV was also stationed here. This one was located on the same airfield and it was combined in the Küstenflieger Abteilung Flandern. This unit consisted of the Kusta III and IV and Marine Schusta I and II. This unit retreated also in the night of 6

October due to the allied advance. Composition Kusta and Marine Schusta at Uitkerke (Spring 1917) III Küstenfliegerabteilung Commander since spring 1917 Lt.d.R. Paul Leffler 6 aircraft IV Küstenfliegerabteilung Commander since spring 1917 Lt.d.R. Bruno Majewski 7 Marineflieger in Flanders 6 aircraft



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1. Schutzabteilung

Commander since spring 1917 Oblt.d.R. Albert Reusch 6 aircraft 2. Schutzabteilung Commander since spring 1917 Lt.d.R. Nagel 6 aircraft

An aerial photo of 1917 on which the aircraft and the two bunkers are visible

The bunkers of the airfield

Looking at the existing archive documentation and the aerial photo of 1917, we can conclude that the bunkers were a part of the accommodation of the airfield of Uitkerke. On the east side of bunker 1, there was a wooden shed. Eight hangars stood to the west of the bunker parallel with the Brugse Steenweg, whereby three on the side of Uitkerke and five in the direction of Brugge. The crew barracks stood on the other side of the Brugse Steenweg and were spread to the Kuiperscheeweg. A witness is bunker 2 which was initially built against the barracks. The airfield was located over an area to the south of bunker 1 to the Kuiperscheeweg.

The bunkers

Bunker 1 is a concrete Construction of 7.5 m long and 5.6 m wide with walls of 65 cm thick. There are two parallel rooms of 5.1 m long and 2 m wide and both rooms give out in a corridor. The two rooms are connected to each other with a door and in both there’s a niche to the outside. Source : Kristof Jacobs



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Bunker 1, plan and outside view



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Bunker 1, the corridor, one of the rooms and the door frame between the rooms.

Bunker 2 is a concrete Construction of 12 long and 7 m wide. On both sides, there’s an entrance porch. The bunker is actually closed and that makes it difficult to determine if there are two rooms or not.



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WORLD WAR 1I

The difference between the Sherman and the Chaffee

tank and its guns This is not an article about fortifications, but I’ve always been fascinated by tanks. That’s why I

wrote this. The US tank Chaffee is identified as a light tank while the Sherman as a medium one, but both are equipped with a 75 mm gun. To make it more intriguing, there’s the 76 mm gun that was also installed in the Sherman tank and the M10. 1 mm difference? Does it make a difference? That was for me enough to start an investigation. So, very high level, the Chaffee (M24) is a light tank, the Sherman (M4) is a medium tank and the M10 is a tank destroyer that operates in the backfield. It’s practical to start with a data table for the Chaffee, Shermans and the M10. That makes it easy to compare while reading M24 M4 M10 M4 76 mm Max armour hull 25 mm 50 mm 37 mm 62 mm Max armour turret 37 mm 75 mm Weight 18,3 ton 30,1-31 ton 29,9 ton 31,7 - 33 ton Max speed 56 Km /hr 38 - 46 Km/hr 48 Km/hr 38 - 46 Km/hr Max range 161 Km 160 - 241 Km 321 Km 136 -257 Km Length 4,98 m 6,2 m 5.97 m 6,2 m

Armament 75 mm M6 75 mm M3 3 inch M7 (76 mm) 76mm M1 Length gun 2.95 m 3,00 m 4.01 m 4,16 -4,44 m Weight gun 185 Kg 405 Kg 902 Kg 517 - 586 Kg

About the M24 Chaffee.

Observations of the experiences of the British with the light M3 Stuart tank in the desert in 1942 showed that a heavier gun was absolutely necessary. The Stuart was equipped with a 37 mm gun. They started with a 75 mm gun and they ended with a test model that was standardised as the M24 Chaffee in May 1944. The first deliveries were done in November 1944 to the 2

nd Cavalry Group.

The tanks took part in December in the Battle of the Bulge. Chaffees operated in 1945 in the Netherlands, Germany, Czechoslovakia and Italy.

A M24 Chaffee tank in the Museum in Beek (NL).



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According to the crews, the tank performed well, but it was not a real counterpart against the powerful German tanks. It didn’t have an impact on the final victory. The gun used in the Chaffee was a 75 mm M6 gun which was also used in the Michell bomber B25H. It had a concentric recoil system which saved turret space and a thinner barrel wall. The M3 used in the Sherman weighted 405 Kg and the M6 only 185 Kg! But, the M6 and the M3 were using the same ammunition and the muzzle velocity was the same. The Chaffee was lighter and quicker than the Sherman. This is a M4 Sherman with the 75 mm M3 gun in Wiltz (Lux).

The next category is the 76 mm gun, used in the M10 and the Sherman. Is there so much difference between this gun and the 75 mm M3 of the Sherman?

The M10 with the 3 inch gun in the museum in Colleville (Fr).

After the success of mounting a 105 mm howitzer on a medium tank chassis, plans were made in April 1942 to install a high velocity gun for the Tank Destroyer Command. The M4A2 chassis was going to be used and the gun was a 3 inch gun M7, also called a 76 mm gun M7. This was big and heavy gun that didn’t fit into a Sherman T6 turret. Its weight was 902 Kg. Therefore it got its own turret, an open top turret. Later on the gun was modified and it became the 76 M1 which was found in the T23 turrets of the Sherman tanks.

In June 1942 the test model was standardized to the M10A1 and the production started. In 1944 the M10 was taken into use by the British and it got the id Wolverine. It was only

late 1944 that the 3 inch gun was replaced by the British 17 Pdr gun which was more powerful. That model was called the Achilles MK IC. This model

came on the battlefield beginning 1945. The Achilles is easy to recognize by the circular counterweight near the muzzle break. The Achilles was the British version with the 17 Pdr gun. La Roche (Be).



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The American observation of the British experiences in the desert in 1942 pointed out that a more powerful gun than the existing 75 mm M3 was needed. In August the US Ordnance Department designed a new high velocity gun that could fire the existing 3 inch anti-tank shell. They kept the weight of the gun as low as possible. It was first tested in September of the same year. It showed that the existing T6 turret was too small and therefore the larger T23 turret was adopted.

The 76 mm M1A1 gun in a T23 turret of the Sherman M4A3 in Clervaux (Lux).

The gun was to compare with the British 17 Pdr gun, but with a lesser penetration performance, although it had a rate of fire that was two times higher and it was easier to operate and to maintain. The gun was put into production from February 1944 on it was available for the Landing in Normandy. Shermans with the British 17 Pdr gun were called Firefly. This is the M4 VC in Tielt (Be).

To conclude, the next tables show the muzzle velocity of the discussed guns and the penetration performance. The 76 mm is not only faster but its penetration capability was a lot higher than the classic 75 mm. The muzzle velocity of the guns 75 mm M3-M6 3 inch 76 mm APC shell 618.7 m/s 792.5 m/s 792.5 m/s HVAP shell 868.6 m/s 1036.3 m/s 1036.3 m/s HE 603.5 m/s

APC = Armour piercing HVAP = High Velocity Armour Piercing HE = High Explosive



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The penetration of shells fired by the guns in cm 75 mm M3-M6 3 inch 76 mm 914 m 1828 m 914 m 1828 m 914 m 1828 m APC 55.9 45.7 88 76 88 75 HVAP 96.5 63.5 135 98 135 64

The 75 mm M6 gun of the M24 Chaffee.

Thanks to Yvonne Mayo for the spell check.

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