Pyotr Levochkin against Ilon Mask: whose rocket engine is better

The General Designer of the Khimkinsky NGO "Energomash" Peter Levochkin this week argued in absentia with Ilon Mask, which rocket engine is better-the Russian RD-180 or the Raptor production of SpaceX. The American billionaire said that his engine surpassed the RD-180 record in terms of pressure, the Russian designer replied that this was not entirely true. The dispute is fundamental, because the RD-180 is one of the few remaining Russian developments, without which the world cosmonautics cannot yet do. If there is an analogue for the engine, Russia will lose this advantage.

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Why is it important

The powerful and reliable RD-180 two decades remains for Russia the subject of national pride. The United States purchases an engine for its heavy ATLAS-3 and Atlas-5 launch vehicles, and it has not yet been created alternatives, so the United States has been forced to withdraw RD-180 procurement from sanctions. Without a Russian engine, the automatic NASA missions to Mars, Jupiter and Pluto would not be possible. In Russia, it should be used on a promising superheavy rocket - "Yenisei".

Raptor creates SpaceX for a promising super-heavy “lunar-Marcian” carrier of Super Heavy. It is close to RD-180 by traction, but uses other fuel and fuel cycle. Now Raptor is in the stage of firing tests.

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Dispute about the characteristics

Ilon Musk: The whole dispute began with the fact that Ilon Musk on his Twitter said that Raptor broke the pressure record in the combustion chamber (one of the engine power parameters), which had previously held the Russian RD-180 (266.7 bar) and reached a value of 268.9 bar.

https://twitter.com/elonmusk/status/1094782854007910400

Peter Levochkin: “In such schemes, this level of pressure in the combustion chamber is not something outstanding-in our developments for these schemes, we lay the pressure level in the chamber of more than 300 atmospheres.”

Who is right here?

Levochkin is right, but a little cunning. Raptor is already working on oxygen and methane now, RD-180 uses a pair of "oxygen-curosin". Developments at Energomash engines on liquefied methane, which the Russian designer speaks of, go back to the sketch project of the RD-169 of the late 1990s. But the tests of the finished product, as the general director of the enterprise Igor Arbuzov said in 2018, will begin no earlier than after three to four years. So far, in Russia there were only tests of other demonstration engines on this fuel.

SpaceX announced the beginning of the design of the methane Raptor in 2012, and the first fire tests of prototypes with reduced parameters were held in the fall of 2016. A successful test of engine parameters approaching target, Musk boasted on February 10, and there really is something to be proud of.

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Pressure is not the main thing

Peter Levochkin: "The pressure parameter itself in the chamber is not an output characteristic of the engine, such as traction and specific impulse."

Who is right here?

Formally, everything is so, but both the engine’s thrust and its specific impulse directly depend on the pressure in the chamber. With targeted 300 bar (296 atm), the Raptor specific pulse (380 C in vacuum) should surpass the Russian RD-180 indicator. And this is the most important parameter of the engine perfection.

Levochkin: “And if you take into account the fact that Energomash certified the engine with a 10%margin, then the pressure in the combustion chamber RD-180 is above 280 atmospheres,” the designer insists.

This is true, but the competitor has the same possibilities. The SpaceX engine can be forceful a little higher than 300 atmospheres, Musk writes , but the laws of physics are already beginning to restrain further growth.

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"The first successes"

Levochkin: “Despite the fact that our companies are competitors, we, as engineers, welcome the first successes of colleagues from SpaceX in the field of rocket engineering. Indeed, when developing the Raptor engine, American engineers reached a record level of pressure in the cell. This indicates a fairly high level of development and production processes in the company of SpaceX. ”

Congratulations on the "first successes" is clearly an overkill. And the point is not even in pressure, but that SpaceX - unlike Energomash - already has a powerful methane engine, sharpened for reusable use. True, it remains to be brought.

Raptor is the third missile engine in history, created according to the closed cycle with full gasification of the components and brought at least to the prototype stage. He has every chance to become the first serial. Such a cycle increases the reliability and efficiency of the engine, which is important for reusable use, but is generally complicated in working out. Methane fuel is much easier than kerosene, remove from the engine after the flight. This allows you to use the engine many times without inter -folk disassembly.

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What is left behind the scenes?

RD-180 is the “half” of the four-chamber RD-170 engine, created for the Energy rocket in the early 1980s. RD-170 was developed at the very peak of then technologies with the involvement of the entire scientific and production power of the Soviet Union. How many of the 16 billion Soviet rubles spent on the Energia-Buran program went to this engine is unknown, but this share is significant. RD-193, engine of the first stage of the latest Russian Angara missile, also from the RD-170 family.

Raptor - created at SpaceX. Mask never disclosed the cost of the program. But in the later stages of the US Air Force, the US Air Force financed the program of the engine option for the EELV dispress missiles for about $ 100 million. Raptor should stand on the first (31 pcs.) And on the second (7 pcs.) Stages of the SpaceX giant reusable rocket (Super Heavy and StarsHip, respectively). The technical risk of this project has been disturbing, but Musk has not yet refused to launch Mars in 2024.

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Is it possible to fly on these engines on Mars?

RD-180 and Raptor have similar specific impulses, because both approach the limit of physically possible for the chemical fuel of energy.

This energy is enough to fly around the moon and landing on its surface, but it begins to lack for a flight to Mars through fast trajectories that minimize the radiation threat to the crew. A two -year flight to Mars on chemical traction, even for radiation protection, reduces the duration of the upcoming life of the astronaut by 2.5 years.

For quick manned flights to Mars and the economically justified development of near -moon orbits, nuclear (yard) or ion reactive engines are needed. Both the USSR and the USA in the 1960-1980s experimented with the yard, but the matter did not go beyond the experiments. Low -power ion engines are widely used to correct satellite orbits, powerful marching engines of this type are only experienced.

Sergey Smirnov