Trembita
By July 2023 Ukrainians were working on a cruise missile, similar to the famous German V-1 flying bombs, powered by a pulsejet engine. The 'garage-made' rocket are to be simple and cheap to produce, so that it can overwhelm the Russian anti-aircraft defense with mass use. The work is conducted by the engineers from the PARS volunteer design bureau and with the participation of volunteers from the ?ivic movement Vidsich. The Ukrainian volunteers started to develop a “people’s” missile called Trembita. [a Trembita is an extra long instrument in the shape of a long, straight pipe also called a Carpathian trombone]
Designers plan to create a small cruise missile with a pulsejet engine. The missile is planned to be used to destroy objects and exhaust the enemy’s anti-aircraft defenses. It is stated that the missile is capable of hitting targets at a depth of 140 kilometers. This aircraft can carry 20kg warheads and can form a large swarm of drones cheaply to break through enemy air defenses.
Trembita is - in terms of the planned function - the Ukrainian equivalent of the Iranian Shahed-131 drones. It is created for the same purpose as them. Massive use of this missile can overpower Russian anti-aircraft defenses. The missile is to carry a 20 kg warhead at a distance of up to 140 km and, according to the Defense 24 website , move at a speed of 400 km/h at an altitude of 30 to 2,000 m. The possibilities of the new weapon seem quite limited, but Trembit's strength is not high technical parameters, but maximum simplicity.
It is a missile uncomplicated in construction and operation, and thus cheap. In practice, this means the possibility of mass, distributed production and the use in attacks of not single missiles, but entire swarms of several dozen, starting from light, mobile launchers. The volunteers want to deploy throughout Ukraine the production of individual parts and components of the rocket in the conditions of garage workshops - a kind of "comprehensive NarodOboronProm". The rocket engine has no moving parts, is easy to manufacture, and runs on gasoline. The launch will be carried out from a pneumatic catapult.
The key advantage of the Trembit is its engine - the projectile is powered by a pulse motor. The painfully loud 100-decibel engine. This, creators say, would strike fear into Russian soldiers in the same way that the distinctive whine of Hitler's V-1 Doodlebugs terrified Londoners during WW2. This type of drive is very simple - it contains a minimum number of moving parts, and the engine's operation is based on a series of micro-explosions, generating a pressure wave that moves through the outlet nozzle.
The disadvantage of the pulse engine is the low thrust at low speeds. The object propelled in this way must be accelerated during take-off using some kind of launcher, ensuring - before the engine starts working - a sufficiently large air flow. This type of engine is not demanding on fuel. According to the constructors of Trembit, their weapons can be powered by E92 or E95 petrol available at gas stations.
Pulse jet engines, or “pulsejets”, are a simple form of internal combustion engine in which combustion occurs in pulses and produces a propulsive exhaust jet. A typical pulse jet engine comprises an air intake fitted with a one-way valve, a combustion chamber, and an exhaust pipe. Air moves into the combustion chamber via the valve. Highly volatile fuels are injected under high pressure into the inlet tubes deflecting the mixture against the combustion chamber forward wall thereby creating a homogenous mixture which is spark ignited; creating a self-sustained resonant combustion cycle.
The exhaust pipe has a natural resonance frequency, and the engine, including operation of the valve and ignition of the fuel, is made to operate at this frequency. Discharge of fuel into the combustion chamber is terminated by the higher pressures therein and is permitted at the lower pressures which reduce to values less than atmospheric. Evidently then, the engine operates intermittently at a cyclic repetition rate that can vary over wide ranges and is essentially proportional to the overall length of the engine. By way of example, a typical cyclic frequency may come within the range of from about 30 cycles per second for relatively long engines to about 200 cycles per second, or more, for shorter engines-Le, 2 /2 to 3 feet in length.
An excellent publication arises out of Project Squid, Department of the Navy, Research Project. Technical Memorandum No.=PR.4 concerning the background and development of the German V-1 "Buzz Bomb" by Ing. Guenther Dietrich translated by A. Kahane, June 30, 1948, Princeton University, and Technical Memorandum No. CAL-27 by Joseph G. Logan, May 1949, by Cornell Aeronautical Laboratories, accentuates some of the tremendous significances of small structural changes and relative dimensions and arrangements of components.
The V-1's unique pulse-jet engine gave the Buzz Bomb its nickname: Louvers opening and shutting rapidly near the intake made a distinctive buzzing noise as the engine's "pulsating" thrust gave the V-1 a cruising speed of about 360 mph. The V-1, which weighed a bit over 5,000 pounds loaded, was launched from a 200-ft. inclined ramp using a steam-powered catapult. Launching accelerated the missile to about 250 mph, fast enough for the winged bomb's jet engine to operate. Since the V-1's range was only around 150 miles, launch sites were set up on the French coast in order to bombard London. Magnetic compasses, a timer and a system of gyroscopes guided Buzz Bombs along a preset course and distance at an average altitude of 3,000 to 4,000 feet. When the course was complete, the 1-ton warhead armed automatically and the engine shut off. The bomb then free-fell onto its target.
Valve pulse-jets such as model airplane engines have an extremely short operating life span such as 15 minutes. The highly developed flat or flap valves of the V-l type power plant has a useful life of an hour or two. This short useful life makes such devices undesirable for a continuous use or reuse in a glider power plant.
| Weight | 100 kg; |
| Weight of the warhead | 20 kg; |
| Range of damage | over 140 km; |
| Speed | over 400 km/h; |
| Maximum flight altitude | 2000 m; |
| Minimum flight altitude | 30 m; |
| Engine | 30 l. |
A pulse jet engine is a relatively simple structure essentially comprising an elongated hollow tube open at its ends and turned upon itself into a generally U-shaped configuration with the open ends thereof facing in the same direction. Such tube is sometimes referred to as a combustor, and intermediate the ends thereof, fluid fuel is introduced into the engine through a nozzle structure located at a section of the tube generally-referred to as the combustion chamber. A sparking device is also located at such combustion chamber, and in operation of the engine, both fuel and air, the latter in suflicient volume to create a combustible mixture with the fuel, enter the combustion chamber and the sparking device is energized to ignite the mixture. Upon ignition of the mixture, the consequent expansion of the gases within the combustion chamber results in a gaseous discharge through the open ends of the engine producing thrust forces tending to propel the engine in a direction opposite to the direction of flow of the gaseous discharge.
Ignition of the fuel within the combustion chamber is accompanied by a rapidly increasing gaseous pressure therein which rises to a value tending to interrupt fuel expression from the nozzle. As the combustion gases expand outwardly from the combustion chamber for discharge through the open ends of the engine, the pressure within the combustion chamber progressively decreases until a value is reached at which a charge of fuel sprays from the nozzle and a reverse flow of the gases toward the combustion chamber is initiated. Such reversal of flow direction results in ambient air being drawn into the combustion chamber for admixture with the fuel charge therein. The combustible mixture of fuel and air is then ignited and the cycle of operation is repeated. The sparking device can be de-energized once the engine commences to run because ignition of the combustible fuel and air mixture is caused by the temperatures attained in the combustion chamber.
The discharge of fuel from the nozzle structure and into the combustion chamber is intermittent as a consequence of the cyclic change in pressure therein from a low value corresponding to the final phases of gaseous expansion during the combustion cycle to a high value corresponding to the initial phases of gaseous expansion following ignition of the combustible mixture; and the pressure at which fuel is supplied to the nozzle.
“Our simple missile is incomparably cheaper than the shots of the enemy’s anti-aircraft missile systems,” the developers note. According to the plans, a salvo launch of 20 of these missiles will allow to overcome the enemy’s air defense and hit targets at a sufficient depth. Volunteers want to deploy the production of the missile’s individual parts and components in the conditions of garage workshops throughout Ukraine. “There is no way the Russians would be able to destroy such an all-encompassing people’s defense industry with their rusty S-300s or high-precision Kalibr missiles,” the designers shared.
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