Chinese Hypersonic Developments (HGVs/HCMs)


tphuang

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Shilao podcast talked about the most recent successful American hypersonic test. Mentioned about how China can track and predict the current American hypersonic development, because it had multiple programs and failures along the way (which did not get reported). American progress in hypersonic program mirrors what happened in China's development in terms of encountering failures along the way. They have a good idea of where AGM-183A will arrive to.
 

taxiya

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Does a rotating detonation engine have any advantage over scramjets ? If so what ?
Detonation engine is about how the combustion works. It has no relationship with speed. In principle it can work from zero speed all the way up to hypersonic.

Scramjet is supersonic combustion Ramjet. It can only work from about mach 4 or 5 above.

So Detonation engine can be a Scramjet as well.

The advantage of detonation engine (particularly rotating version) is start from stand-still. It can replace the rocket boosters or turbine engines that accelerate the scramjet to minimum working speed.
 

gelgoog

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No, a detonation engine uses a different operating principle than a scramjet. Like the name implies, one uses detonation of fuel, the other uses deflagration of fuel. Detonation engines in principle should be both more efficient and higher performance. But getting them to work reliably is really tricky.

A pulse jet engine, like the one used in the V-1 buzz bomb from WW2, uses a similar operating principle to a detonation engine. But the operating frequency of the engine in a pulse jet, related to the time between each detonation, is low enough that the performance is lower than modern jet engines. Modern detonation engines are supposed to operate at much higher frequency to get to their high performance level and are hard to make in practice. Vibrations can easily destroy the engine. And like a pulse jet a detonation engine is noisy like hell. So this won't be used in civilian transport that is for sure.

 
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SEAD

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No, a detonation engine uses a different operating principle than a scramjet. Like the name implies, one uses detonation of fuel, the other uses deflagration of fuel. Detonation engines in principle should be both more efficient and higher performance. But getting them to work reliably is really tricky.

A pulse jet engine, like the one used in the V-1 buzz bomb from WW2, uses a similar operating principle to a detonation engine. But the operating frequency of the engine in a pulse jet, related to the time between each detonation, is low enough that the performance is lower than modern jet engines. Modern detonation engines are supposed to operate at much higher frequency to get to their high performance level and are hard to make in practice. Vibrations can easily destroy the engine. And like a pulse jet a detonation engine is noisy like hell. So this won't be used in civilian transport that is for sure.

that’s a pulse detonation engine, not RDE. PDE is also a promising power but for now RDE is closer to practical.
 

gelgoog

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RDE is not deflagration and is nothing like a scramjet.
At best you might say they are both heat engines which can operate in a given Mach regime band. That is all.

The difference between a PDE and an RDE is that in one you have a linear combustion chamber and in the other you have an annular one. It is analogous to regular jet engines which can have linear, even multiple, combustion chambers or annular ones. But the operating principle and physics are the same and all are jet engines.
 
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SEAD

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RDE is also pulsed. It’s just the rotary mechanism controls the pulses rather than depending on a valve.
Nope. The fire (burning region) ‘runs’ through a circle (drum), it’s not pulsed. There’re also oblique detonation engines, which are also continuous burning but the region is fixed.
 
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