Author Topic: JAXA S-520-31 Detonation Engine tests (Read 3523 times)

WormPicker959 · « **on:** 08/19/2021 05:32 pm »

Thought I'd start a post about the Detonation Engine experiments that just launched! Here we have 6s duration burns of two detonation engine experiments (rotary and pulsed), both seem to have gone well! Hopefully we'll learn more about the two experiments as the data is further analyzed and released.

Here's a link to Chris Bergen's tweet about it:

https://twitter.com/NASASpaceflight/status/1428310836855050246?s=20

Here's a link to the machine-translated JAXA page about it:

https://translate.google.com/translate?sl=auto&tl=en&u=https://www.isas.jaxa.jp/topics/002693.html

WormPicker959 · « **Reply #1 on:** 08/19/2021 05:37 pm »

Some highlights from the translated page (forgive the bad translations):

"After the first stage motor is separated, the rotary detonation engine (operating for 6 seconds, thrust 500N) and pulse detonation engine (operating for 2 seconds x 3 times) operate normally in outer space, and the image, pressure, temperature, vibration, and position , I got the posture data"

"The success of this space flight demonstration experiment has greatly increased the possibility that the detonation engine will be put into practical use for deep space exploration kick motors, rocket first-stage and two-stage engines, etc."

Let the Isp speculation begin!

WormPicker959 · « **Reply #2 on:** 08/19/2021 05:48 pm »

Based on some sleuthing from this article from Japan times, it looks like this is a paper describing the RDE:

https://arc.aiaa.org/doi/full/10.2514/1.B38037

It looks like this particular engine gets around ~144s Isp in the lab and a rocket sled, which seem low to me? They're using gaseous ethylene and oxygen here.

AllenB · « **Reply #3 on:** 08/19/2021 05:50 pm »

Interesting -- hadn't heard much about these before, but had assumed they were air breathers.

Do we know the fuel and oxidizer?

And in the "really dumb question" category, since you mention Isp, would such an engine be expected to deliver higher Isp? Or are the advantages elsewhere? I'd been under the impression that current engines deliver fairly close to the "optimal" Isp for a given propellant combination.

Either way, nice to see progress. One flight test is, IMHO, worth an awful lot of theory and talk.

WormPicker959 · « **Reply #4 on:** 08/19/2021 05:54 pm »

Quote from: AllenB on 08/19/2021 05:50 pm

Do we know the fuel and oxidizer?

Gaseous Ethylene and Oxygen

Quote from: AllenB on 08/19/2021 05:50 pm

And in the "really dumb question" category, since you mention Isp, would such an engine be expected to deliver higher Isp? Or are the advantages elsewhere? I'd been under the impression that current engines deliver fairly close to the "optimal" Isp for a given propellant combination.

I don't know! I'd probably have to go back and rewatch Scott Manley's video on the subject. The Jaxa press release talks about the "effeciency" - which I assumed to mean Isp - and the decreased size of the engine compared to thrust generated - so this seems like TWR to me. But I don't know what the benefits are!

Edit: On the Isp front, here's Fig. 10 from the attached paper re: a ground test of what I think is this engine:

Yiosie · « **Reply #5 on:** 08/19/2021 06:59 pm »

Cross-post from the suborbital thread for launch:

Quote from: Fmedici on 07/27/2021 07:23 am

A S-520 sounding rocket was launched from Uchinoura on 26 July at 20:30 UTC:

https://www.jaxa.jp/press/2021/07/20210727-1_j.html

https://www.sankei.com/article/20210727-REFI2C6ZQZKHFP737N36UI7LNY/

Quote
Successful new engine experiment JAXA launches sounding rocket
The Japan Aerospace Exploration Agency (JAXA) installed a new engine under development at the Uchinoura Space Center in Kimotsuki Town, Kagoshima Prefecture on the 27th, which uses shock waves generated by the explosive reaction of a mixed gas of fuel and oxygen. , Launched sounding rocket "S-520" No. 31. According to JAXA, the experiment was successful with the aim of demonstrating engine performance in outer space.

The launch was at 5:30 am on the same day. The rocket rushed through the almost cloudless sunrise sky with a dazzling light, and about 20 seconds later, it reached a high sky that was invisible to the naked eye. Applause came from the JAXA staff who witnessed.

If a technology that uses shock waves as a propulsion force is put into practical use, it can be expected that energy efficiency will be improved by reducing the weight of the engine. JAXA is working on development as a core technology for exploring distant space.