Chinese Research into Reusability

[sanman]

Here's an article about research in China toward developing recoverable/reusable rocket stages to lower the cost of space launch:

http://www.scmp.com/news/china/policies-politics/article/2079822/china-developing-system-recover-reuse-parts-space

SpaceX has performed a series of successful vertical landings which demonstrate the technology’s feasibility, but Chinese researchers have rejected the approach, the article said.
Deng wrote that the vertical landing system needed carrying extra fuel for landing, which meant rockets could only carry smaller payloads into space.
...
The Chinese launch vehicle academy researchers have said on their website that the parachute-airbag system will be assisted by multiple censors and a sophisticated flight control system to guide the descent. The final goal was to hit a small recovery zone as precisely as the vertical landing technology can achieve.

So it seems that in the comparison of fuel+legs against parachutes+airbags, that the latter is seen as a better option, at least at this juncture.

How soon could we see stuff flying?

[ChrisWilson68]

The Chinese launch vehicle academy researchers have said on their website that the parachute-airbag system will be assisted by multiple censors

Those Chinese sure are serious about their censorship!

[Johnnyhinbos]

The Chinese launch vehicle academy researchers have said on their website that the parachute-airbag system will be assisted by multiple censors

Those Chinese sure are serious about their censorship!

I think it's "Censor Ship"...

[MikeAtkinson]

So it seems that in the comparison of fuel+legs against parachutes+airbags, that the latter is seen as a better option, at least at this juncture.

Neither parachutes or airbags scale well.

Not too bad a solution for a smallsat launcher, but starts to get iffy at EELV size (not sure if Vulcan could return whole stage by parachute even if they wanted to). Parachutes and airbags are completely impractical at New Glen let alone ITS size.

Also airbags and parachutes add quite a bit off mass, probably not as much mass as the extra fuel for a powered landing, but replacing cheap fuel with expensive hardware and extra refurbishment may end up more expensive in the end.

[FutureSpaceTourist]

I think this quote is more telling:

Deng Xinyu, a researcher on the Chinese rocket recovery programme, said that vertical landing involved many challenges and was extremely difficult to achieve.

Is the real reason they rejected it because they don't think they can do it?

[notsorandom]

So it seems that in the comparison of fuel+legs against parachutes+airbags, that the latter is seen as a better option, at least at this juncture.

Neither parachutes or airbags scale well.

Not too bad a solution for a smallsat launcher, but starts to get iffy at EELV size (not sure if Vulcan could return whole stage by parachute even if they wanted to). Parachutes and airbags are completely impractical at New Glen let alone ITS size.

Also airbags and parachutes add quite a bit off mass, probably not as much mass as the extra fuel for a powered landing, but replacing cheap fuel with expensive hardware and extra refurbishment may end up more expensive in the end.

The STS SRB's were recovered via parachute and had a dry mass of around 90 metric tons. They were really strong, being a lot sturdier than a liquid stage. Air bags might be pretty tricky for something that big though.

[su27k]

So it seems that in the comparison of fuel+legs against parachutes+airbags, that the latter is seen as a better option, at least at this juncture.

Neither parachutes or airbags scale well.

Not too bad a solution for a smallsat launcher, but starts to get iffy at EELV size (not sure if Vulcan could return whole stage by parachute even if they wanted to). Parachutes and airbags are completely impractical at New Glen let alone ITS size.

Also airbags and parachutes add quite a bit off mass, probably not as much mass as the extra fuel for a powered landing, but replacing cheap fuel with expensive hardware and extra refurbishment may end up more expensive in the end.

Didn't Kistler plan to use parachutes and airbags? K-1 is a bit small for EELV but not a smallsat launcher either. I suspect this choice may have something to do with the engine arrangement on the new Chinese LVs, they don't have a lot of engines, so it would be difficult for them to do retro-propulsion landing without some dedicated landing engines.

[Prettz]

So it seems that in the comparison of fuel+legs against parachutes+airbags, that the latter is seen as a better option, at least at this juncture.

Neither parachutes or airbags scale well.

Not too bad a solution for a smallsat launcher, but starts to get iffy at EELV size (not sure if Vulcan could return whole stage by parachute even if they wanted to). Parachutes and airbags are completely impractical at New Glen let alone ITS size.

Also airbags and parachutes add quite a bit off mass, probably not as much mass as the extra fuel for a powered landing, but replacing cheap fuel with expensive hardware and extra refurbishment may end up more expensive in the end.

From the animation it looks like they only want to use this for strap-on boosters.

[savuporo]

Previous reports about reusable launcher research in China have cited rocket debris falling over populated areas as the main driver of this.

Steerable semi autonomous parafoils would make quite a bit of sense for this IMHO. Especially because the tech is very much dual use. Think JPADS-30K equivalent systems

[TrevorMonty]

Surprised they didn't do mid air recovery with helicopter, the boosters a light enough for it.

[Dalhousie]

I think this quote is more telling:

Deng Xinyu, a researcher on the Chinese rocket recovery programme, said that vertical landing involved many challenges and was extremely difficult to achieve.

Is the real reason they rejected it because they don't think they can do it?

Or not worth doing at this stage.  Remember the economic viability of reusability has yet to be demonstrated.

[Coastal Ron]

I think this quote is more telling:

Deng Xinyu, a researcher on the Chinese rocket recovery programme, said that vertical landing involved many challenges and was extremely difficult to achieve.

Is the real reason they rejected it because they don't think they can do it?

Or not worth doing at this stage.  Remember the economic viability of reusability has yet to be demonstrated.

The ability to successfully recover a stage using parachutes and landing a stage on it's side has not been proven either, yet they appear to be betting their program on that assumption.

Landing a stage vertically under power has been proven, both on land and at sea.  By more than one U.S. company.  Is it difficult?  Of course.  Many things in life are, yet humanity still does them.

There is something going on in the Chinese launch vehicle academy that we don't yet understand with regards to their goals for reusability, and the resources they want to devote to achieving that.  And they may have internal conflicts that are not yet resolved, which is why we see this pooh-poohing of what SpaceX has done.

[ChrisWilson68]

I think this quote is more telling:

Deng Xinyu, a researcher on the Chinese rocket recovery programme, said that vertical landing involved many challenges and was extremely difficult to achieve.

Is the real reason they rejected it because they don't think they can do it?

Or not worth doing at this stage.  Remember the economic viability of reusability has yet to be demonstrated.

That's kind of like saying "the ability of an aircraft carrrier to win a war has yet to be demonstrated, so we're going to keep sinking all our money into battleships" in 1940.

[Dalhousie]

I think this quote is more telling:

Deng Xinyu, a researcher on the Chinese rocket recovery programme, said that vertical landing involved many challenges and was extremely difficult to achieve.

Is the real reason they rejected it because they don't think they can do it?

Or not worth doing at this stage.  Remember the economic viability of reusability has yet to be demonstrated.

That's kind of like saying "the ability of an aircraft carrrier to win a war has yet to be demonstrated, so we're going to keep sinking all our money into battleships" in 1940.

What you are proposing is like saying we should stop all investment in battleships in 1902 because there is some interesting work happening in heavier than air flight in a few places.

Note that there is nothing that says that China is not interested in further work this field.They have merely decided that one approach is not viable.   

[tonya]

Some similarity to what might have been Energia's approach to booster recovery.

http://www.buran-energia.com/energia/energia-consti-1eretage.php

[ChrisWilson68]

I think this quote is more telling:

Deng Xinyu, a researcher on the Chinese rocket recovery programme, said that vertical landing involved many challenges and was extremely difficult to achieve.

Is the real reason they rejected it because they don't think they can do it?

Or not worth doing at this stage.  Remember the economic viability of reusability has yet to be demonstrated.

That's kind of like saying "the ability of an aircraft carrrier to win a war has yet to be demonstrated, so we're going to keep sinking all our money into battleships" in 1940.

What you are proposing is like saying we should stop all investment in battleships in 1902 because there is some interesting work happening in heavier than air flight in a few places.

Note that there is nothing that says that China is not interested in further work this field.They have merely decided that one approach is not viable.

In 1902, it would be 40 years before aircraft carriers were demonstrated to win wars.  In 1940, that would be demonstrated within 5 years.

So, you think it's 1902 with respect to reusable rockets and I think it's 1940.  In other words, if reusable rockets demonstrate economic viability within 5 years, I'm right.  If they demonstrate economic viability only after 40 more years, you're right.

Place your bets now.  SpaceX, Blue Origin, ULA, Arianespace, Russia, and China have placed theirs.

[Dalhousie]

I think this quote is more telling:

Deng Xinyu, a researcher on the Chinese rocket recovery programme, said that vertical landing involved many challenges and was extremely difficult to achieve.

Is the real reason they rejected it because they don't think they can do it?

Or not worth doing at this stage.  Remember the economic viability of reusability has yet to be demonstrated.

That's kind of like saying "the ability of an aircraft carrrier to win a war has yet to be demonstrated, so we're going to keep sinking all our money into battleships" in 1940.

What you are proposing is like saying we should stop all investment in battleships in 1902 because there is some interesting work happening in heavier than air flight in a few places.

Note that there is nothing that says that China is not interested in further work this field.They have merely decided that one approach is not viable.

In 1902, it would be 40 years before aircraft carriers were demonstrated to win wars.  In 1940, that would be demonstrated within 5 years.

So, you think it's 1902 with respect to reusable rockets and I think it's 1940.  In other words, if reusable rockets demonstrate economic viability within 5 years, I'm right.  If they demonstrate economic viability only after 40 more years, you're right.

Place your bets now.  SpaceX, Blue Origin, ULA, Arianespace, Russia, and China have placed theirs.

Still a bad analogy. Barring the STS, nobody has demonstrated technical reusability of an orbital launch system.  Nobody has yet demonstrated economic viability of such systems. It will take several years for this to happen, at best.  Maybe longer.  In 1970 many of us thought we were on the verge of reusable rockets too.

In 1940 nobody questioned the importance, indeed centrality, of heavier than air maritime aviation.  In 1902 nobody knew it it was possible (barring man-carrying kites). 

But you are missing the points here, not just making a poor historical analogy.  The points are that 1) the Chinese may be quite justified in giving up one particular approach (not that they can't achieve it) and 2) the case for reusability, is not yet as clearcut as wishful thinking would have it.

[gospacex]

SpaceX rocketcams show it rather clearly. 1st stage goes down from near vacuum into atmosphere at a frightening velocity, visually at Mach 5 or more, and at 45 degrees or steeper. How chutes are going to stop this?

[TrevorMonty]

The Chinese are doing reusability to lower their domestic launch costs. They not competiting inter nationally, so any saving is a success.

[ChrisWilson68]

The Chinese are doing reusability to lower their domestic launch costs. They not competiting inter nationally, so any saving is a success.

Ah, but they are still competing internationally, because if they let a U.S. launch company provide much cheaper launch to the U.S. military then China is at a strategic disadvantage.

[ChrisWilson68]

I think this quote is more telling:

Deng Xinyu, a researcher on the Chinese rocket recovery programme, said that vertical landing involved many challenges and was extremely difficult to achieve.

Is the real reason they rejected it because they don't think they can do it?

Or not worth doing at this stage.  Remember the economic viability of reusability has yet to be demonstrated.

That's kind of like saying "the ability of an aircraft carrrier to win a war has yet to be demonstrated, so we're going to keep sinking all our money into battleships" in 1940.

What you are proposing is like saying we should stop all investment in battleships in 1902 because there is some interesting work happening in heavier than air flight in a few places.

Note that there is nothing that says that China is not interested in further work this field.They have merely decided that one approach is not viable.

In 1902, it would be 40 years before aircraft carriers were demonstrated to win wars.  In 1940, that would be demonstrated within 5 years.

So, you think it's 1902 with respect to reusable rockets and I think it's 1940.  In other words, if reusable rockets demonstrate economic viability within 5 years, I'm right.  If they demonstrate economic viability only after 40 more years, you're right.

Place your bets now.  SpaceX, Blue Origin, ULA, Arianespace, Russia, and China have placed theirs.

Still a bad analogy.

You haven't provided any evidence or reasoning to support it being a bad analogy.

Barring the STS, nobody has demonstrated technical reusability of an orbital launch system.  Nobody has yet demonstrated economic viability of such systems.

Just like in 1940 nobody had demonstrated winning a war with aircraft carriers.

It will take several years for this to happen, at best.

Even if it takes 5 years from today for SpaceX and/or Blue Origin to do it, if it's going to happen, it's a mistake for China and other launch providers not to be going full speed on reusability at least to the SpaceX level right now.  It takes time to design, build, and test a new launch vehicle and to iron out all the bugs.

China and the rest are already way behind.  The fact that they still aren't embracing it means it will just take them longer to catch up.

Maybe longer.  In 1970 many of us thought we were on the verge of reusable rockets too.

In 1940 nobody questioned the importance, indeed centrality, of heavier than air maritime aviation.

That is not remotely true.  It was fiercely debated within all the world's major navies.  Both the U.S. and Japan had aircraft carriers, but also battleships.  Many still viewed battleships and cruisers as more important.  Huge sums were wasted right up until the war started building battleships and cruisers.  Partway through the war, as it became apparent that aircraft carriers were so much more effective, many ships of other types that were under construction were converted to aircraft carriers, or just scrapped to start from scratch with carriers.

In 1902 nobody knew it it was possible (barring man-carrying kites). 

But you are missing the points here, not just making a poor historical analogy.  The points are that 1) the Chinese may be quite justified in giving up one particular approach (not that they can't achieve it)

That's exactly what the traditionalists said about battleships in the 1930s.

and 2) the case for reusability, is not yet as clearcut as wishful thinking would have it.

Again, we'll see.  If it takes more than 40 years, you're right, it's 1902.  If it takes five or fewer, you're wrong.

[savuporo]

The Chinese are doing reusability to lower their domestic launch costs. They not competiting inter nationally, so any saving is a success.

Definitely competing on international market. Small wins so far, but they do.

And again, a significant driver for their investments such as Wenchang launch complex and stated reason for reusability research, which has been going on for a couple years now, is to improve the public image.

[Dalhousie]

Again, we'll see.  If it takes more than 40 years, you're right, it's 1902.  If it takes five or fewer, you're wrong.

In either case you are still wrong.  The value of maritime aviation was demonstrated by 1916.  I would hope that reusability in some form will have been demonstrated by 14 years from now.  Assuming  that progress rates will be comparable.  Which is unlikely. 

But you are still missing the point.  It's not the time scale, it's the readiness of the technology. To date nobody has reused a first stage, unless you want to count the SRBs. 

[ChrisWilson68]

Again, we'll see.  If it takes more than 40 years, you're right, it's 1902.  If it takes five or fewer, you're wrong.

In either case you are still wrong.  The value of maritime aviation was demonstrated by 1916.  I would hope that reusability in some form will have been demonstrated by 14 years from now.  Assuming  that progress rates will be comparable.  Which is unlikely. 

But you are still missing the point.  It's not the time scale, it's the readiness of the technology. To date nobody has reused a first stage, unless you want to count the SRBs.

You're still not getting it.  I specifically said "demonstrated to win wars" because that's the equivalent of your "demonstrated economic reuse".  Lots related to reuse has been demonstrated already.  Asking that economic reuse be demonstrated by a competitor is like asking that aircraft carriers demonstrate they can win a war by winning a war.  By the time that happens, it's too late.

Anyway, I'm sure you won't get that either, but I'm confident other readers of this thread will understand, so I'm done with the conversation now.

[Dalhousie]

Again, we'll see.  If it takes more than 40 years, you're right, it's 1902.  If it takes five or fewer, you're wrong.

In either case you are still wrong.  The value of maritime aviation was demonstrated by 1916.  I would hope that reusability in some form will have been demonstrated by 14 years from now.  Assuming  that progress rates will be comparable.  Which is unlikely. 

But you are still missing the point.  It's not the time scale, it's the readiness of the technology. To date nobody has reused a first stage, unless you want to count the SRBs.

You're still not getting it.  I specifically said "demonstrated to win wars" because that's the equivalent of your "demonstrated economic reuse".  Lots related to reuse has been demonstrated already.  Asking that economic reuse be demonstrated by a competitor is like asking that aircraft carriers demonstrate they can win a war by winning a war.  By the time that happens, it's too late.

Anyway, I'm sure you won't get that either, but I'm confident other readers of this thread will understand, so I'm done with the conversation now.

I get what you are saying and still think you are wrong both analogically and factually.  The failure to understand is your part.

[FutureSpaceTourist]

Reusable craft are in CASIC's plans
Beijing (XNA) Jun 08, 2017

China Aerospace Science and Industry Corp, one of the nation's major space contractors, said on Tuesday it is developing reusable spacecraft capable of taking off and landing at airports.

Liu Shiquan, deputy general manager of CASIC, told the 2017 Global Space Exploration Conference, which opened on Tuesday in Beijing, that the cutting-edge spacecraft's key technologies and major parts - such as its engine - have passed ground tests and the program is proceeding smoothly.
[...]

http://www.spacedaily.com/m/reports/Reusable_craft_are_in_CASICs_plans_999.html

[AncientU]

...  I would hope that reusability in some form will have been demonstrated by 14 years from now.  Assuming  that progress rates will be comparable.  Which is unlikely. 

But you are still missing the point.  It's not the time scale, it's the readiness of the technology. To date nobody has reused a first stage, unless you want to count the SRBs.

10 days later... someone did.  Refurbishing the booster cost much less than half that of a new one.

Next week another reused first stage launches; two more are being test fired for FH with others in the queue before year's end.  I'd say the technology is ready.  Do you really think the Chinese believe otherwise?

Your move...where do the goal posts go next?

Repeating this quote... a head shaker for sure.

I would hope that reusability in some form will have been demonstrated by 14 years from now

[eeergo]

From ChinaSpaceFlight  :


https://twitter.com/cnspaceflight/status/886839417096216576

[SmallKing]

From ChinaSpaceFlight  :


https://twitter.com/cnspaceflight/status/886839417096216576

There are two plans so far, parafoil and multi-parachute, both for laning a strap-on booster

[eeergo]

From ChinaSpaceFlight  :


https://twitter.com/cnspaceflight/status/886839417096216576

There are two plans so far, parafoil and multi-parachute, both for laning a strap-on booster

Thank you for the paper! Google-translating I get that the China Academy of Launch Vehicle Technology's Institute of Aerospace Systems Engineering and the Beijing Institute of Space Electrical and Mechanical have performed crane tests, air drop tests, real size (?) airbag prototype development and landing impact testing, and they have achieved an accuracy of several hundred meters in landing.

How advanced are they into implementing it into a vehicle? Is this a "general" (vehicle-agnostic) development for now, or is it more geared toward the CZ-5/7 boosters? I assume the hypergolic old-generation boosters are not considered for recovery?

[SmallKing]

From ChinaSpaceFlight  :


https://twitter.com/cnspaceflight/status/886839417096216576

There are two plans so far, parafoil and multi-parachute, both for laning a strap-on booster

Thank you for the paper! Google-translating I get that the China Academy of Launch Vehicle Technology's Institute of Aerospace Systems Engineering and the Beijing Institute of Space Electrical and Mechanical have performed crane tests, air drop tests, real size (?) airbag prototype development and landing impact testing, and they have achieved an accuracy of several hundred meters in landing.

How advanced are they into implementing it into a vehicle? Is this a "general" (vehicle-agnostic) development for now, or is it more geared toward the CZ-5/7 boosters? I assume the hypergolic old-generation boosters are not considered for recovery?

Seems like subscale, if it goes well, I reckon it will be used in old Changzheng series firstly for some test of controlled crash

[zhangmdev]

That paper left out a few important parameters like drop test article weight, size, drop altitude, separate/touchdown velocity, parachute/parafoil size and weight. I think those are just proof-of-concept tests. Don't expect to controlled-crash recover old CZ boosters any time soon.

[FutureSpaceTourist]

Interesting from Steve Jurvetson:

Well, looks like someone got right on this challenge… And they concluded there is one best way to do it!
https://www.chinaspaceflight.com/satellite/Linkspace/Linkspace.html chinaspaceflight
#flattery

https://twitter.com/dfjsteve/status/909066542511353856

Edit to add:

I saw it on twitter before spotting discussion in SpaceX competition thread:
http://forum.nasaspaceflight.com/index.php?topic=39688.msg1723915#msg1723915 

[Darkseraph]

This video is linked on the above companies website, although I can't translate the page.

http://v.youku.com/v_show/id_XMjg2NzA2NTg0OA==.html

By the appearance of the tests in the video, they would appear to be at a similar stage to Masten or Exos.

[Kryten]

The same video is on their youtube channel.

[john smith 19]

Here's an article about research in China toward developing recoverable/reusable rocket stages to lower the cost of space launch:

http://www.scmp.com/news/china/policies-politics/article/2079822/china-developing-system-recover-reuse-parts-space

Which was what SX thought at first as well.

Then they decided it wasn't going to meet their goals and switched to propulsive RTLS.

I note that the Chinese, along with most current mainstream aerospace companies  favor the "one big engine" approach to reliability, which demands pretty deep throttling for a landing.

It may be that given the Chinese starting point propulsive RTLS is a lot harder for them to implement.

[john smith 19]

From ChinaSpaceFlight  :
There are two plans so far, parafoil and multi-parachute, both for laning a strap-on booster

Interesting paper, although I only read the abstract and looked at the pictures.

It looks like they aim to go with one system for both stages, so mass efficiency is important to them up front.

The problem with all these systems is the recover stresses don't align with the launch stresses. Unless you can spread those loads very efficiently in the axis at right angles to the thrust axis (typically the strongest axis on a VTO ELV stage) it will crumple. The other option is a re-design of the stage structure, which is likely to be quite extensive.

Obvious questions are do they launch over land or sea? If it's land then low accuracy is not really an issue (as long as it's reasonably flat) but if it's sea then I'd guess it's got to get a lot better if they plan to land it on some kind of vessel.

TBH if I had a clean sheet (and the cash) for an RLV design I'd launch from the vessel so the stage was over land for recovery. It took SX 5 attempts to land on the barge, but they nailed land landing first time out, admittedly after the experience of the earlier failed sea landings and Grasshopper. That suggests a stationery landing pad is a lot easier target.

[SmallKing]

From ChinaSpaceFlight  :
There are two plans so far, parafoil and multi-parachute, both for laning a strap-on booster

Interesting paper, although I only read the abstract and looked at the pictures.

It looks like they aim to go with one system for both stages, so mass efficiency is important to them up front.

The problem with all these systems is the recover stresses don't align with the launch stresses. Unless you can spread those loads very efficiently in the axis at right angles to the thrust axis (typically the strongest axis on a VTO ELV stage) it will crumple. The other option is a re-design of the stage structure, which is likely to be quite extensive.

Obvious questions are do they launch over land or sea? If it's land then low accuracy is not really an issue (as long as it's reasonably flat) but if it's sea then I'd guess it's got to get a lot better if they plan to land it on some kind of vessel.

TBH if I had a clean sheet (and the cash) for an RLV design I'd launch from the vessel so the stage was over land for recovery. It took SX 5 attempts to land on the barge, but they nailed land landing first time out, admittedly after the experience of the earlier failed sea landings and Grasshopper. That suggests a stationery landing pad is a lot easier target.

I agree with you
They plan to land on land

[john smith 19]

I agree with you
They plan to land on land

In which case high accuracy is not the driving force it is for a barge landing.

[GreenShrike]

It took SX 5 attempts to land on the barge, but they nailed land landing first time out, admittedly after the experience of the earlier failed sea landings and Grasshopper. That suggests a stationery landing pad is a lot easier target.

I'd not take SpaceX's early barge experiences as anything for or against barge recoveries. *Targeting* was never the issue; things like running out of hydraulic fluid, sticky throttle valves, collapsing landing legs, or propellant depletion were.

If you can't reach the recovery area at all, or you run out of landing prop, or you touch down but your legs fail, then barge or landing pad, your stage is toast. Of the four failures, three were hardware faults, one was a mission planning fault, and none of them were issues unique to the barge. Only the valve issue might not have doomed the stage if it had happened on land, due to the potentially larger acceptable landing radius, resulting in less erroneous fine maneuvering control. On the other hand, if your stage can't manage to bring itself upright at touchdown, it doesn't really matter what's under it as it tips over.

However, downrange land touchdowns do eliminate the ocean from the list of things trying to kill your booster (and barge!), so is definitely worthwhile. As such, I'd certainly take downrange land recoveries over water given the choice.

I'll admit that I'd like to see parachute/parafoil recoveries attempted, if only so they can be crossed off the list of things yet to be attempted. With a landing accuracy of "several hundred metres", you can't practically have a prepared landing pad, but the airbags mean you don't exactly need one. You also avoid needing to choose between many main engines, a very deeply throttleable single main engine and dedicated landing engines, and just use whatever you've got on the shelf. SpaceX's 3-engine re-entry burns do indicate that much less overall throttling is needed for re-entry, so perhaps single large main engines will suffice there as well.

On the other hand, if I recall correctly, Blue is designing their booster to not require an entry burn, so maybe the need can be avoided entirely. Of course Blue is also going with barge recoveries despite the risk to their large and undoubtedly rather expensive 7m booster.

Interesting times. :-)