Japan successfully tested a rocket engine that was propelled by shock waves produced by burning a mixture of methane and oxygen gases, the country’s space agency said Tuesday.

Known officially as a pulse detonation engine (PDE), it was launched aboard a S-520-31 sounding rocket – a powerful single-stage rocket capable of lofting a 100 kilogram payload far above 300 kilometres – from the country’s Uchinoura Space Center in Kagoshima Prefecture at around 5:30 am on 27 July..

It reached an altitude of 235 kilometres, four minutes and four seconds after launch and landed in the sea southeast of Uchinoura about eight minutes later, Japan Times reports.

JAXA later retrieved a capsule containing test data in nearby waters.

“This experiment is the world’s first flight demonstration of rocket engine technology that safely and efficiently converts shock waves (explosive waves) generated when a mixed gas of fuel and oxygen reacts explosively into thrust,” JAXA said, according to Parabolic Arc.

https://room.eu.com/news/japan-successfully-tests-rocket-engine-propelled-by-shock-waves

What’s the advantage?

dv said:

What’s the advantage?

My limited understanding is that the advantage is similar to the advantage of other pulsed jet combustion applications. Both in ramjets and in furnaces.
Simplicity and stability.

Spiny Norman said:

Japan successfully tested a rocket engine that was propelled by shock waves produced by burning a mixture of methane and oxygen gases, the country’s space agency said Tuesday.

Known officially as a pulse detonation engine (PDE), it was launched aboard a S-520-31 sounding rocket – a powerful single-stage rocket capable of lofting a 100 kilogram payload far above 300 kilometres – from the country’s Uchinoura Space Center in Kagoshima Prefecture at around 5:30 am on 27 July..

It reached an altitude of 235 kilometres, four minutes and four seconds after launch and landed in the sea southeast of Uchinoura about eight minutes later, Japan Times reports.

JAXA later retrieved a capsule containing test data in nearby waters.

“This experiment is the world’s first flight demonstration of rocket engine technology that safely and efficiently converts shock waves (explosive waves) generated when a mixed gas of fuel and oxygen reacts explosively into thrust,” JAXA said, according to Parabolic Arc.

https://room.eu.com/news/japan-successfully-tests-rocket-engine-propelled-by-shock-waves

> pulse detonation engine (PDE), it was launched aboard a S-520-31 sounding rocket.

LOL. Do you see the bad pun? The pulse detonation frequency of the engine produces a sound.

> This can significantly reduce overall weight and cost – a benefit its developers say could enable the production of engines just one-10th of the current size.

I can well believe a reduction in weight and cost, because of lower complexity.

But I can’t believe the claim of a significant reduction in size … only … yes the size can be reduced perhaps even to one-10th of the current size … but there’s a caveat.
The reduction is size is accompanied by an equivalent reduction in power. So we’re talking here about the production of a small lightweight rocket engine of insignificant power. The result would be a bipropellant rocket engine competing directly with hypergolic rocket engines and monopropellant rocket engines.

The fuel is used with much greater efficiency, as it is detonated supersonically, not burnt subsonically.

https://en.wikipedia.org/wiki/Pulse_detonation_engine

PDEs are a development offshoot of pulsejet engines:

https://en.wikipedia.org/wiki/Pulsejet

Used in the German V1 cruise missile of WW11:

https://en.wikipedia.org/wiki/V-1_flying_bomb

PDE sound:

https://www.youtube.com/watch?v=z_5MHEboFp0

Pulsejet sound:

https://www.youtube.com/watch?v=WCsKs2NhdWg

V1 sound:

https://www.youtube.com/watch?v=Q1qsBGTkVSk