Glider interceptor firm “Blom und Voss” BV 40. January 1943 started mass raids of British bombers compounds on German cities. Armada of bombers flying in close formation, known as the “combat box”, providing mutual support by their fire side 12.7 mm machine guns. German fighters struggled to overcome the barriers of the escort fighters and defensive fire of the bombers before they reach the ability to attack the target. Losses were high and the efficiency low. In this regard, the task of countering allied bombers became for Germany a priority. Her decision was attended by many design teams that have submitted their, sometimes very original projects. Perhaps the most unexpected proposal was submitted by the firm “Blom und Voss” glider interceptor V 40. Let us try to retrace the thinking of its creators.
The inspirer and organizer of the project was the Director of an aviation Department of the company “Blom und Voss”, is engaged in shipbuilding, doctor-engineer Richard Vogt. Early in his career he was prone to unexpected and original solutions, bordering on technical adventurism (which is, for example, the asymmetric scout 141 V, was produced by small series). All the more surprising that the technical Department of RLM (Reichsluftministerium -Reyhsministerstvom aviation) has supported his project.
Dr. Richard Vogt was part of the experience of air combat is known that frontal attacks are more likely to succeed as a fire bomber in the forward hemisphere is weaker than in the rear. So, it is advisable to attack in the forehead. During the attack, the fighter, the FW 190 for example, is a very visible target, because its frontal projection is about 1.5 m2 and is determined by the size of the air-cooled engine. The goal shooter bomber detects from a great distance, and with 900 m can affect on-Board 12-mm machine guns.
How to radically reduce the “forehead” of the interceptor? – Even removing the engine! But if the pilot be placed in the supine position, the frontal view will decrease even more. Such a small target will be hard to find side shooters, and this increases the chances of success. Making such a conclusion, Vogt suggested RLM the idea of a motorless glider interceptor, made from abundant materials and up to combat the height of a normal fighter. Despite the originality of the proposal, R. Vogt officially supported by RLM, and his project has received preliminary designation Р186.
The first prototype of the BV 40 glider. Side marking – PN+UA. The gun has not been established. Visible bulletproof glass and the armor flap on side window. Note the flat face of the cab is welded from armor plates
BV 40 the side view. Visible to the mast with a pipe LDPE, rocking and traction of the ailerons and “speed” keel on which you installed the stabilizer
Initially, the glider interceptor was supposed to equip one gun, caliber 30 mm. cannon If the queue reaches the goal, Р186 was to RAM the target wing! It is clear that the pilot should be in a well armored cockpit. If in this case will not be able to hit the target, in the presence of the clearance and the speed of the glider shoots up and the next bomber dropped “Herat slinge” (a shell loop) cable, with a small explosive charge. Of course, all of this looks like fantasy. Especially questionable collision attack on a collision course with a closing speed of 900 km/h.
Some sobering came when started to count. R. Vogt quickly realized that wing for ramming attacks must be very strong, and therefore heavy. This threatened the entire project. Therefore, from the ramming attack was abandoned. Refused “Herat slinge” from questionable ideas. There is only one frontal attack with the gun. As this attack is extremely fast, decided to install two 30-mm cannons MK.108. Two guns provided greater density of fire and hit at least one 30-mm projectile will cause significant damage to the bomber, and maybe even knock him out. Ammo decided to limit the 35th shells on the barrel – still greater number, he can’t shoot in a single attack.
Structurally Р186 was a cantilever high-wing monoplane with the classical scheme. The glider is manufactured from abundant materials, and the design tried to make as simple and cheap. It was assumed that to build it will be the ordinary plumbers, welders and carpenters who are not familiar with the aviation industry. Special attention was paid to the protection of the pilot. The front of it was covered with bulletproof glass thickness of 120 mm and 20-mm armor plate. Small side Windows with sliding breastworks had bulletproof glass thickness of 50 mm. the Side surface of the cab and fold the top panel was made of armor thickness of 3 mm. the Bottom of the cab, closed 5 mm, and the legs of the pilot – 8-mm armor. As you can see, protecting the pilot was very substantial and allowed him to walk confidently to the attack on the bomber, armed with 12.7 mm machine guns.
The small middle part of the fuselage was made of tin and steel sections and assembled on the rivets. The tail part was made of wood, had plywood sheathing and fastened to the middle part on the bolts.
BV 40 – rear view. Above the stabilizer visible hinge brackets of the Elevator and thrust with the rocking of the rudder
The BV 40 glider in the factory yard. The figure of a man can appreciate the small size of the interceptor. Handle for opening of the lamp tilted 45°. In the photo you can see that the wing has a different thickness from the fuselage and on the outer part. Glider fixed ropes – the first of them geared to the knot, which is attached to the brace discharged the take-off trolley. The crutch of the airframe is on the stand (cart)
The designers happily take their brainchild to the test. It is possible to estimate the size of the glider. The man in the black suit pulls the car the handle opening of the lantern
Right wing was all-wood construction consisting of a main spar, two auxiliary (front and rear) and plywood sheathing. Somewhere in polarisman wing dramatically changed the profile from approximately 17.7% in the middle part, by 12.7% in foreign parts. Why this is done is not very clear. The ailerons were of wooden frame and plywood sheathing. Р186 had a pretty significant load on the wing is about 115 kg/m2, which required at planting apply effective flaps. Had to retreat from the principle of simplicity – the flap made dvuhmetrovym! As a consequence, there was quite a complex kinematics, brackets, control rods and hinges are all made of metal. Under normal landing flaps were deflected 50°, and in an emergency it can be reject at 80°. The wing was attached to a metal fuselage with four bolts.
The tail Assembly is of classic design, with a strut stabilizer is made of wood. The Elevator had a trimmer instead made adjustable stabilizer, another departure from the principle of simplicity. The stabilizer could deviate within ±4,5°.
The landing gear consisted of runway two-wheeled waste carts, retractable skis and tail suspension crutch. Takeoff was supposed to be completed at 30-m wire, towed for fighter Bf 109G or FW 190. Armament consisted of two guns MK.108 30 mm caliber ammunition for 35 rounds per gun. Guns were installed under the root ribs of the wing was covered by a metal hood. The sight was absent, instead, the windshield was applied aiming the crosshairs.
Glider interceptor had a minimum set proteininteractions devices. The compass was placed outside the cabin. Inside the steel cab it just didn’t work. There was also an intercom, which with the help of the wire was connected to the aircraft tug. Oxygen system was simplified and consisted of cylinder, gearbox and oxygen masks. This is not surprising because the interceptor had to operate at altitudes up to 9000 m.
The layout of the glider interceptor R 186 was prepared in the autumn of 1943, after which it showed the leadership of the RLM. The project was approved and received the official designation of the BV 40, which is not visible the initials of the designer, Richard Vogt (Richard Vogt), from which we believe that the designation has the name of the company – “Blom und Voss” (Blohm und Voss). It was a departure from the German system in which the techniques were assigned the initials of the main constructor. In December 1943, was ordered six prototypes. To reduce the weight of the first four cars, V1, V2, V4 and V5 had facilitated the booking and only one gun. V3 was used for static tests. Prototypes IMAPI side marking from PN+to PN UA+UF.
The first flight of the BV 40V1 was performed on may 6, 1944, the Tug served as a Bf 110. After landing, the pilot reported that the stability and controllability of the glider in normal flight, including in the turbulent air behind the tug. There were some comments on the process of takeoff. The airframe is modified for greater stability on the runway increased the runway track of the truck and lowered the pressure in the wheels.
The second flight was made on 2 June 1944 at the airfield in Wenzendorf. Glider unhooked from the tow at an altitude of 800 m, with a speed of 240 km/h During the flight, the latter gradually reduced to 150 km/h. Controllability was normal, but upon reaching a speed of 140 km/h the glider suddenly, without warning signs, did a wing-over and crashed on the border of the airfield. The cause of the accident was investigated, but tests decided to continue — the good, the second sample was ready, and frustrated first decided to renovate.
The second prototype BV 40V2 performed two flights on 5 June. There were no comments. Three days later, made two flights in which the cutaway was performed at altitude of 2200 m, was achieved speed of 330 km/h without comment, any prerequisites that led to the previous disaster, was not observed. Meanwhile, the testing involved a prototype fourth – 40V4 WU (V 40VЗ was used on ran). This car is not lucky – it was badly damaged during the landing, after one of the flights. The car replaced the fifth sample.
The sixth prototype WOO 40V6 July 27 was distilled from STADA SRL in Wenzendorf towed behind a Bf 110. It was the first relatively long trip. After landing, the pilot reported that the flight was very tiring. Long to lie on his stomach, resting his chin in focus, it was very hard. As if there was not, at the end of July, after 19 test flights, I decided that the main part of the tests completed. At the height of 2000 m was achieved at a speed of 470 km/h. Stability and control there was a good. Believed that in a dive can reach speeds of 900 km/h. But studies of high-velocity decided to be held in late summer of 1944 Feared Aileron flutter and oscillation of other parts of the structure.
Double slit flap released in the end position – at an angle of 80°. Show the device of the flap, such a complex design in the projects of the gliders did not use one
The cockpit glider interceptor BV 40
Interceptor BV 40, the front view. About as it was to watch ARTStrelka enemy bombers. The photo shows that the wing has a different thickness along the span
RLM gave an order for 20 V 40, with a term of readiness to March 1945, with the further deployment of serial production with the rate of 10 gliders per month. Parallel to the Technical management of planned improvement in V 40, up to changing the purpose of the glider. Wanted to reduce the area of the ailerons to eliminate flutter, set of rocket or pulse engine, to provide a small glider (to deal with bombers), or Vice versa – large (for ground attacks) bombs, to convert it into a guided bomb, or to use as a towed fuel tank. But it was an empty fantasy in October 1944 14 gliders in the factory, in various stages of completion, were destroyed during a RAID by allied aircraft and the program was closed. Such is the dialectic – a means of combating bombers, these bombers were destroyed.
Did this project the chances of success? Try to understand. As you know, every technological device is created to solve any tasks. For V 40 the task is clear – to bring down an enemy bomber. But in order to accomplish this, the aircraft needs to have different qualities (properties), and sequentially execute a series of steps before hitting the target.
These stages are the following:
1. It is necessary to establish the fact of an enemy RAID (this is care ground services).
2. You need to fly, to gain altitude and leave the area to find the goals.
3. To find the enemy and to begin with it convergence. It is necessary to avoid defeat on the part of the fighter escort.
4. To enter the range of effective fire. To avoid destruction from fire on-Board guns of the bomber.
5. To open fire and hit the target.
6. To attack the next target.
7. To return to the airfield and prepare for the next departure.
This list is to correct, clarify and expand (I do not claim to truth in the last instance).
If we look closely at the properties of the glider interceptor/ 40, we see that he is able to perform well only item 4, and then only partially. Do: armored cockpit and the pilot is well protected. The glider has a small size, and its hard to see enemy arrows. So under enemy fire it is likely to survive. But there is a limitation of the attack is only possible from the front hemisphere. From the rear hemisphere glider anyone to catch up can’t. How are things going with the remaining items? Detection and convergence is fully borne by the tow, the glider pilot then plays no role. It also depends on the choice of time and space uncoupling in V 40. If the point of uncoupling chosen incorrectly – the task is completed. To correct the errors glider can’t, because he had no motor. And to come at the right place at the right time (either a point or uncoupling position to open effective fire fighter) – the task is not simple. Even for a fighter that has the motor and ability to maneuver.
But let’s say all failed – target. The remaining items also in doubt. Attack the second target is hardly possible – the glider is losing altitude constantly, and in the case of landing even a perfectly good interceptor/ 40 outside the airport for his return to home becomes a problem. In addition, there remained suspicions about the presence of system errors in the draft. Because the cause of stalling during the second flight never found. And this defect could suddenly become apparent.
As you can see, this design is optimized to perform only one point of the requirements for the interceptor. Other requirements are displayed in brackets. Can this unit effectively carry out its mission? With great certainty we can say no. This answer is based on other examples from the history of aviation. For example: light bomber, the Yak-4 was “designed” to achieve high speed. It made a favourable impression on Stalin and the car was launched. Soon began the war has shown the complete futility of the Yak-4 as a combat aircraft. It turns out that in addition to the speed, the bomber must have other important qualities…
Another example from more recent time: an American fighter-bomber F-117. Fighter of characteristics in it a little, rather it is a light bomber. Design the F-117 focused on achieving invisibility in the radar range of frequencies. Other flight data has faded into the background. Bomber F-117 participated in combat missions, well done the task, but the Americans are very quickly removed him from service. And this despite the most perfect equipment and advanced electronics. Apparently, the overall costs for the F-117 was large and the efficiency is small.
From the above it is again possible to conclude that aircraft – the result of a compromise between various conflicting requirements. And how competently the compromise achieved depends on the success of the project. As for/ 40, then it should be treated as an interesting curiosity in the history of aviation is no aviation power didn’t even try to repeat.
Basic data BV 40
Ekipaj……………………………………………………………………………………………………………………..1 people
The scope kryla……………………………………………………………………………………………………………..7,9 m
Dline…………………………………………………………………………………………………………………………5,7 m
Area kryla………………………………………………………………………………………………………..8,25 m2
Weight postage…………………………………………………………………………………………………………..840 kg
Takeoff mass…………………………………………………………………………………………………………950 kg
Load krylo…………………………………………………………………………………………………115 kg/m2
The area of the frontal projection of the cab…………………………………………………………………………..0,6 m2
The maximum towing speed………………………………………………………………………555 km/h
Gliding speed with maximum quality………………………………………………300 km/h
The maximum speed in a dive (estimated)……………………………………………….900 km/h
Time of climb to 7000 m when towing Bf 109G (estimated)………………………12 min.
Weapons…………………………………………………………2 gun MK-108 with 35 rounds per gun
K. KUZNETSOV
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