Friday, 10 January 2014

Tanks in the Air

Some of you may have read about attempts to make a tank fly. Here is a brief summary of Soviet efforts:

"After 1939-1940 tank transport experiments involving TB-3 and TB-4 planes, mass production of mounts for the TB-3 plane started at the end of 1940. As of May 1941, the Army has 130 mounts for the TB-3 plane capable of carrying T-37 and T-38 tanks, up to 3.3 tons in mass. There are no mounts for the T-40 tank, 5.5 tons in mass.
The Committee of Defense order #23ss dated February 28th, 2941 ordered the People's Commissariat of Heavy Machine-building to produce 20 mounts for the TB-3 plane capable of carrying 3.3 tons, and 12 mounts for the TB-7 plane capable of carrying 4.5 tons.
On May 12, 1941, GABTU chief Lieutenant-General of Tank Forces comrade Fedorenko reported to the Head of the General Staff of the Red Army comrade Zhukov, in letter #145965s, that the order was not fulfilled.
According to information from the Aero-paratroop Directorate of the Red Army, the reason for this was that TB-3 and TB-7 planes are discontinued, and are not available in large numbers.
In 1942, attempts to tow a T-60 with wings (in a glider configuration) with two TB-3 planes were conducted, but ceased for the same reason.
The Aero-paratroop Directorate is suggesting that the experiments restart, except with two P-8 planes towing a T-60.
However, based on the above information, I deem that it is currently impossible to use T-60 tanks in paratrooper operations.

Engineer-Captain Bukatin
Assistant of the Chief of the 6th Department of GABTU KA
April 4th, 1944"

-CAMD RF 38-11355-1377

Bukatin was right, efforts to make a tank glide were unsuccessful in WWII. However, there are other ways of getting a tank in the air.

From Tanks Theory, N.I. Gruzdev.

The equations provided describe how to figure out a jump that lands the tank in such a way that it lands flatly, and does not significantly damage the components.

If the jump is performed incorrectly, the tank may be damaged: "The jump was performed off a wooden ramp, half a meter high, and angled 5 degrees, over a 30 meter wide river, off a 7.5 meter tall shore...
...The tank reached a speed of about 65 kph, flew 30 meters through the air, hit the opposite shore with its front. Upon traveling 20 meters on the opposite shore, the driver stopped the tank. After examining the tank, the right front and rear balancers were significantly bent. After examination, the vehicle was capable of independently driving away." - from the Russian State Military Archive

In the 1938 movie "Tankers", a number of tank maneuvers were shown, including a jump into a river. From the memoirs of the director Grebnev: "We only had bad luck once. We needed to film a tank jumping over a river from a tall shore. We found a small river that flows into the Luga. Started filming. The first jump was successful, but we needed a second take, to be sure. Camera, jump, and...the tank got stuck in the middle of the river. The river was sandy, the ground was damaged by the first jump, and didn't hold out for the second. What a catastrophe! With two tanks, we had to drag that one out of the water, where we had to clean it for an entire day. But the commanders did not get angry. They thought of it as gathering experience. If they had to do it in a war, two tanks should not jump in one place."

The BT series could jump well, but what about the T-26? It did not want to get left behind!



"Report on the trials of the TPP-2 vehicle, confirmed by Barykov
1938, Leningrad, Kirov factory #185
January

The TPP-2 tank "Tank Preodoleniya Prepyadstviy" [Obstacle Crossing Tank] is designed to cross obstacles by jumping over them. A jump in this case is defined as the tank breaking contact with the ground and flying through the air freely. Currently, tanks jump in two ways:
  1. Using a naturally occurring difference in terrain height.
  2. Using a ramp, or an artificially occurring difference in terrain height.
The TPP-2 is designed to use the kinetic energy of a moving tank.
In order to test the principle of jumping using an artificial ramp, a tractor on the T-26 chassis was used. In order to increase speed, the tank's mass was reduced, and the tractor was without:
  • The upper armour plate (roof)
  • Track covers
  • Various equipment, extra braces
  • The tank was only loaded with 1/3rd of its fuel capacity
Despite all this, the TPP-2 was not significantly lighter than a regular T-26, which is seen in the component weights:
  1. Hull: 4770 kg
  2. Suspension: 940 kg
  3. Tracks: 748 kg
  4. Eccentric gear: 484 kg
  5. Automatic gearbox: 334 kg
    Total mass: 7276 kg
The mass of the production machinegun and cannon armed T-26 is 8300 kg, so weight reduction of one ton was achieved.

Order and results of trials

Trials of the tank were as follows, and had the following results:
November 26, 1937

Function of the automatic mechanisms, (priming, launching, eccentric rotation, fixation mechanism) was tested in place, with the tank on a tall jack. The entire system was also checked this day by being launched with two 12 volt batteries. The system was also checked by being launched with the engine. No defects that would prevent testing were observed.

November 27, 1937

The tank was tested on the factory's race track. The tank moved at 23-25 kph. After priming and releasing the automatic mechanism, it triggered without fault, but the eccentrics did not rotate fully, and the tank did not jump, due to the icy ground and a lack of friction. The tank performed a U-turn and lost speed rapidly. 
When the tank was inspected, the following defects were found:
  • Four gear teeth were broken (part 91-108)
  • Two direction limiters were broken (part 10x20N44)
  • The right half-axle was caught in the pipe and was damaged (part 91-108)
  • One of the teeth on the quadrant broke, and cut off the rear of the plug (part 91-112)
  • The pusher shaft was bent (part 93-3)
  • The crankcase lug in the area of the pusher shaft ruptured
December 26, 1937

After correcting the aforementioned defects, a second attempt at a trial was made. In order to increase the tank's speed, a special track was built with packed snow covered in sand. A speed of 25 kph was achieved. In order to improve the friction on the eccentrics, they were equipped with spurs, and turned off automatically when reaching a wooden ramp at the end of the track. The results were as follows:

Trial #1: The mechanism worked flawlessly, the tank jumped in the air, but due to the sharp loss of speed, did not jump very far, and landed on its tracks roughly.

Trial #2: The mechanism worked flawlessly, the tank was launched in the air, but due to the loss of speed, the eccentrics did not have time to rotate fully. The tank landed very roughly.

The poorer performance in the second trial can be explained by the eccentrics' half-axles, attached to pipes on the suspension, steel on steel, were stuck.

After these trials, the following defects were found:
  • One gear tooth broke (part 91-108)
  • The crankcase developed a crack next to the pin attachment
  • The front and rear eccentric half-axles were stuck in the suspension, and show scuffs.
December 31st, 1937

After correcting the aforementioned defects, and due to removing the air filter from the engine, the tank reached 30 kph on an improved track. At this speed, the mechanisms performed flawlessly, the tank was raised by the eccentrics, the eccentrics rotated fully, but the tank lost speed rapidly and barely jumped at all. The tank landed roughly.

Conclusions:
  1. It was proven that propelling the tank into the air using its kinetic energy with an artificial ramp (the eccentrics) is possible.
  2. The TPP-2 prototype has the following defects preventing it from achieving satisfactory performance:
    1. Insufficient speed, and therefore insufficient kinetic energy, of the tank
    2. A suspension that is too stiff, resulting in rough landings leading to destruction of the mechanisms
    3. Unsatisfactory attachment of the eccentrics to the hull of the tank, preventing them from working properly. 
  3. As a result of the above, subsequent trials of the TPP-2 will not be productive, and must cease. Use the TPP-2 as a tractor.
  4. Department #8 must continue experimental design work on jumping tanks.
  5. The design of the TPP-2, despite trials results, can be evaluated as follows:
    1. The mechanism was designed well, and must be used as an example of what can be done with limited dimensions using an existing vehicle. 
    2. Individual assemblies are of interest, and are designed boldly and originally.
    3. Individual parts of the mechanism are of interest, their design indicates excellent engineering thought, and demands close attention.
    4. The driver's seat, with hydraulic shock absorbers and straps, is very successful, and should be standardized used on other tanks.
  6. Defects are as follows:
    1. Unacceptable use of steel on steel in the eccentric half-axles.
    2. Unacceptable location of the eccentrics, reducing the tank's clearance from 380 mm to 260 mm.
Chief of the #2 Bureau of the 8th department engineer Masalkin
Military representative of the RKKA ABTU, military engineer 3rd grade, Poklonov

Trials and assembly managers:
Section chief of the #2 Bureau of the 8th department engineer Fedorov
Engineer-designer of the #1 Bureau of the 8th department, engineer Linder

Chief of the 8th department Gudkov"

3 comments:

  1. It's kind of funny, I thought of those old Speed Racer cartoons and the jacks that went "chok-chok-chok" when they catapulted the Mach 5 into the air. "In Japanese anime, you make race cars jump. In Soviet Russia, you make tanks jump."

    Jokes aside, how far did the Russians test their suspension in those days? I know that modern MBTs jump off ramps all the time, but did the Russians do that as part of their regular testing, rather than the experiments described here?

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    1. As far as I know, regular suspension testing involved bumpy terrain (with some decently sized bumps, tens of centimeters in height). The tank could clear the ground if it went fast enough, but not ridiculous ramps like this.

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