Nazi Germany (1943)
Glider-fighter – 6 prototypes
By the middle of the Second World War, the Germans were losing control of the skies over the occupied territories. Even the Allied air attacks on Germany itself were increasing. In an attempt to stop these raids, the Blohm und Voss company presented the Luftwaffe with a new project which involved using cheap gliders in the role of fighters. While a small series would be tested nothing came from this project.
History
By 1943, the German Luftwaffe (air force) was stretched to limits in an attempt to stop the ever-increasing number of Allied air attacks. The Allied Bombing campaign particularly targeted German war industry. During this time, there were a number of proposals on how to effectively respond to this ever-increasing threat. Proposals like the use of a large number of relatively inexpensive fighter aircraft, that were to be launched from larger aircraft, were considered with great interest. One proposal went even further by suggesting the use of an inexpensively modified glider for this role. This idea came from Dr. Ing Richard Vogt who was the chief designer at Blohm und Voss.
In mid-August 1943, Dr. Ing Richard Vogt handed over the plans of a cheap and easy to build (without the use of strategic materials which were in short supply) glider that could be built by a non-qualified workforce to the German Ministry of Aviation (Reichsluftfahrtministerium – RLM). The pilots intended to fly this glider were to be trained in basic flying skills only. The initial name of this Gleitjäger (glider fighter) was P186 which would later be changed to Bv 40. After receiving the initial plans the RLM responded at the end of October 1943 with a request for six prototypes to be built. The number of prototypes would be increased to 12 December 1943 and again to 20 in February 1944. If the project was successful, a production order of some 200 per month was planned.
Design
The Bv 40 was designed as a partly armored and armed, mixed construction, fighter glider. Its 0.7 m (2ft 3 in) wide fuselage was mostly constructed using wooden materials, while the cockpit was provided with armored protection. The front armor of the cockpit was 20 mm (0.78 in) thick, the sides were 8 mm (0.31 in), and the bottom 5 mm (0.19 in) thick. Additionally, the cockpit received a 120 mm thick armored windshield.
The wings and the tail unit were also built mostly using wooden materials. The rear tail had a span of 1.75 m (5ft 9in). For towing operation, the Bv 40 was provided with a jettisonable trolley that was discarded once the Bv 40 was in the air. Once it was back to the airbase it was to land using a skid.
What is interesting is that in order to have as small a size as possible, the cockpit was designed so that the pilot had to be in a prone position. While a pilot prone positioned design offered advantages like being a smaller target and having an excellent view at the front, it also caused some issues like a bad rearview. While this design was tested in Germany (like the Akaflieg Berlin B9 for example), it was never implemented. Inside the cockpit, there were only basic instruments that were essential for the flight. In addition, due to the high altitude that it was supposed to operate, the pilot was to be provided with an oxygen supply system and a parachute. The side windows had sliding armored screens with integral visor slots that could offer extra protection.
The armament of this glider consisted of two 3 cm (1.18 in) MK 108 cannons. These were placed in the wing roots with one on each side. This was serious firepower which could cause a huge amount of damage to the target it hit. Due to its small size, the ammunition loadout was restricted to 35 rounds per cannon. The ammunition feed system was quite simple; it consisted of a rectangular ammunition feed hatch placed in the middle of each wing. Inside the wings, an ammunition conveyor chute was placed to guide the rounds directly to the cannons. There was also a secondary option which included the use of one cannon together with the ‘Gerät-Schlinge’ 30 kg (66 lb) towed guided bomb. This bomb was to be guided by the Bv 40 toward the enemy bombers and was then detonated at a safe distance. In practice, during testing, this proved to be almost impossible to achieve success.
Other weapon systems were also proposed. For example the use of R4M rockets placed under the wings. There was also a proposal to use the Bv 40 in the anti-shipping role by arming it with four BT 700 type torpedoes or even using 250 kg (550 lbs) time-fused bombs. Due to the extreme weight increase, this was never possible to achieve.
How should it be used?
In essence, the glider was to be towed by a Me-109G to a height of around 6 km before being released. Once released, it was to engage incoming enemy bombers with its two 3 cm (1.18 in) cannons. If circumstances allowed, a second attack run was to be launched. After the attack, the pilot simply guided the glider to the nearby airbase. It was hoped that the small size and armored cockpit would be the pilot’s best defense.
Testing of the Prototypes
Once the first prototype (marked PN+UA) was completed in early 1944, the first test flight made at Hamburg-Finkenwerder was unsuccessful as it was not able to take-off from the ground. A second more successful attempt was made on the 6th (or 20th depending on the source) May 1944 at Wenzendorf. Despite being intended to have an armored cockpit, the first prototype was tested without it. It appears also that during the maiden flight it was towed by another unusual Blohm und Voss design: the asymmetrical Bv 141. But according to most sources, the Me-110 was to be used, which seems more plausible. After the first flight, some modifications to the jettisonable undercarriage were made. On the 2nd June 1944, the first prototype was lost during a crash landing.
A few days later the second prototype (PN+UB) made its first test flight. During a dive, it managed to reach a speed of 600 km/h (370 mph). Its final fate is unknown but it was probably scrapped. The third prototype never took off from the ground as it was used for static structural tests. The fourth prototype (PN+DU) was lost during its first test flight but the precise date is unknown. The fifth prototype (PN+UE) made its first test flight on 6th July 1944, but its fate is also unknown. The last prototype (PN+UF) was tested with a new fin section and made its maiden flight on the 27th of July 1944.
During these test flights, the Bv 40 was able to achieve a flight speed of up to 650 km/h (404 mph). During dive testing, the following speeds at different altitudes were achieved: 850 km/h (528 mph) at 4,000 m (13,120 ft), 700 km/h (435 mph) and an astonishing 900 km/h (560 mph) at 5,000 (16,400 ft). Nevertheless, the results of the test flight appear to have been disappointing due to Bv 40’s poor overall flight performance.
Rejection of the Project
Once the project was properly revised by the RLM officials, the obvious shortcomings of the Bv 40 became apparent. The Bv 40 was simply deemed too helpless against the Allied fighter cover. In addition, when the report of the first few prototypes was studied, it became clear even to the RLM that the Bv 40 was simply a flawed concept and so it decided to cancel it in mid-August 1944. The next month the Allies bombers destroyed the remaining 14 Bv 40 which were in various states of production.
Not wanting to let their project fail, the Dr. Ing Richard Vogt and the Blohm und Voss designers proposed to mount either two Argus As 014 pulsejets or two HWK 109-509B rocket engines under its wings. Nothing came from this as the Me-328 and Me-163 proved to be more promising (these ironically also ended in failure). There was even a proposal to modify the BV 40 to be used as a Rammjäger (ram fighter) which was never implemented.
Production
Despite initial requests for the production of 200 such gliders only a small prototype series would be built by Blohm und Voss during 1944.
- Bv V1 – Lost during its second test flight.
- Bv V2 – Fate unknown.
- Bv V3 – Used for static testing.
- Bv V4 – Lost during it’s first flight.
- Bv V5 – Flight tested but final fate unknown.
- Bv V6 – Tested with modified fin section.
- Bv V7-V20 – Lost during one of many Allied bombing raids on Germany.
Operators
Germany – While testing was conducted on a small prototype series no production order was given.
Conclusion
The Bv 40 on paper had a number of positive characteristics; it was easy to make, could be available in large numbers, was cheap, well-armed and it did not need skilled pilots. But in reality, the poor performance, lack of a power plant, low ammunition count, and its vulnerability to Allied escort fighters showed that this was a flawed concept. This was obvious even to RLM officials who put a stop to this project during 1944.
Gallery
Illustration by Ed Jackson
Blohm und Voss Bv 40
Blohm und Voss Bv 40 Specifications |
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| Wingspan | 25 ft 11 in / 7.9 m |
| Length | 18 ft 8 in / 5.7 m |
| Height | 5 ft 4 in / 1.63 m |
| Wing Area | 93.64 ft² / 8.7 m² |
| Empty Weight | 1.844 lbs / 830 kg |
| Launch Weight | 2.097 lbs / 950 kg |
| Climb rate to 7 km | In 12 minutes |
| Maximum diving speed | 560 mph / 900 km/h |
| Cruising speed (when towed) | 344 mph / 550 km/h |
| Maximum Service Ceiling | 23,000 ft / 7,000 m |
| Crew |
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| Armament |
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Sources
- J. Miranda and P. Mercado (2004) Secret Wonder Weapons of the Third Reich: German Missiles 1934-1945, Schiffer Publishing.
- R. Ford (2000) Germany Secret Weapons in World War II, MBI Publishing Company.
- Jean-Denis G.G. Lepage Aircraft Of The Luftwaffe 1935-1945, McFarland and Company.
- M. Griehl (2012) X-Planes German Luftwaffe Prototypes 1930-1945, Frontline Book.
- D. Herwig and H. Rode (2002) Luftwaffe Secret Projects, Ground Attack and Special Purpose Aircraft, Midland.
- http://www.warbirdsresourcegroup.org/LRG/luftwaffe_blohm_und_voss_bv40.html
- https://www.flugrevue.de/klassiker/kampfgleiter-blohm-voss-bv-40/