Author Topic: Blue Origin - New Shepard second developmental test flight and landing  (Read 126391 times)

Offline mlindner

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Here are the slides from that presentation. Currently 500 staff at Blue. The BE-3 and BE-4 are available to all launch providers.

Quote
BE-3 engine throttles down to low power to reduce descent rate to 5 mph for landing

So it's confirmed that the landing is not a hoverslam and that it capable of a T/W ratio of 1. This won't be possible for their orbital vehicle unless they sacrifice engine efficiency heavily. It would be interesting to calculate how many engines would be required given the thrust ratios of the first stage to second stage (BE-4 vs BE-3U) and if this would be enough for reusability without cropping the engine bell.
« Last Edit: 11/29/2015 12:00 pm by mlindner »
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Offline Oli

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This won't be possible for their orbital vehicle unless they sacrifice engine efficiency heavily.

They can use BE-3 for landing, or a LNG version of it.

Offline cscott

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Here are the slides from that presentation. Currently 500 staff at Blue. The BE-3 and BE-4 are available to all launch providers.

Quote
BE-3 engine throttles down to low power to reduce descent rate to 5 mph for landing

So it's confirmed that the landing is not a hoverslam and that it capable of a T/W ratio of 1. This won't be possible for their orbital vehicle unless they sacrifice engine efficiency heavily. It would be interesting to calculate how many engines would be required given the thrust ratios of the first stage to second stage (BE-4 vs BE-3U) and if this would be enough for reusability without cropping the engine bell.
I don't agree that that statement is "confirmation".  The 5mph figure could be instantaneous.

I agree that the video evidence seems to suggest a controlled descent at a fixed rate, I'm just quibbling over the standards we use for confirmation.

In particular, we seem to have a 20,000lb thrust minimum "confirmed" as well, and if their booster stage weighs 20,000lb empty, their mass fraction is terrible.  There are a bunch of "facts" which don't quite fit together; let's try to be very careful about what we "know".

Offline guckyfan

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In particular, we seem to have a 20,000lb thrust minimum "confirmed" as well, and if their booster stage weighs 20,000lb empty, their mass fraction is terrible.  There are a bunch of "facts" which don't quite fit together; let's try to be very careful about what we "know".

Seems perfectly acceptable for a suborbital vehicle that reaches a maximum altitude of 100km vertically up. It makes landing so much easier, grasshopper like.

Offline LouScheffer

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In particular, we seem to have a 20,000lb thrust minimum "confirmed" as well, and if their booster stage weighs 20,000lb empty, their mass fraction is terrible.  There are a bunch of "facts" which don't quite fit together; let's try to be very careful about what we "know".
Actually, what we know hangs together quite well.  We know the engine has a max thrust of 110,000 lbs-force (or about 490,000 newtons) and a min of 20,000 lbs-force (89,000 Newtons).  We don't know the ISP, but another hydrogen, sea-level, not-pushing-limits engine is the RS-68, with sea-level ISP of 365 and vacuum ISP of 410, so it's probably similar.

BO states that the acceleration at cutoff is a little over 3 Gs.  Assuming a little over means about 3.2-3.3, the mass at cutoff is about 15000-16000 kg.  We know 3600 kg (8000 lb) of this mass is the capsule ( http://www.thespacereview.com/article/2871/1 )   This leaves 11,400-12,400 or thereabouts for the booster + landing fuel.

At full thrust and ISP of 365, the engine would consume 137 kg/sec of fuel.  From the landing video, it looks like 10 sec of full thrust followed by 10 sec of hovering (say 20% thrust) so that's 12 seconds of full thrust, or about 1600 kg of fuel for the landing (plus whatever margin they allowed).  So the empty booster should be about 10,000 kg.  This also makes sense since we can see it (more or less) hover, so it must mass at least 9,000 kg.

For the way up, a ballistic trajectory to 100 km takes 1400 m/s (from v = sqrt(2*a*s)).  BO says the ascent takes 2.5 minutes, or 150 sec, so gravity losses will be 1470 m/s.   New Shepard is a small rocket so drag losses will be large, say 230 m/sec, for a  total of 3100 m/s.  Assuming an average ISP of 390, the rocket equation demands a mass ratio of 2.25.  This means the takeoff mass was about 34000-35000 kg.  This gives a takeoff thrust/weight of 1.5, which seems about right.

So the following is consistent with all that is known.   Total takeoff mass is 34,600 kg or so.   19,000 kg of fuel is used for the trip uphill, leaving a mass of 15,600 kg at cutoff.   The 3,600 kg capsule is jettisoned leaving 12,000 kg, composed of 2,000 kg fuel for landing plus 10,000 kg for the empty booster.

You can't fiddle with these numbers too much without violating some of the known constraints.  The conclusion is that the New Shepard vehicle is built like a tank (the army fighting vehicle, not the liquid storage device).  This makes perfect sense since it is intended to be re-used many times with quick turnaround.

Offline cscott

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Your numbers are convincing, but I'm not sure how they are consistent with Bezos' statement:
Quote
“(For) our orbital plans, we’ve leased pad 36 at Cape Canaveral, and we’re building an orbital system, but the first stage — the booster stage of that — will be architecturally identical to the vehicle that we just flew because the environments and everything else are very, very similar, and having demonstrated that, we’ve basically validated that architecture with this flight,” he said.
http://spaceflightnow.com/2015/11/24/bezos-backed-blue-origin-achieves-rocket-landing/

A booster "built like a tank" is fundamentally incompatible with an orbital vehicle.  Much of that poor mass fraction seems to be visible to the naked eye in the form of ring fins, drag flaps, actuated front and aft guidance fins, and sturdy bacteriophage retractable legs.

So I'd personally tend to side with your numbers rather than Bezos here.  I'm just trying to maybe sure we keep straight the fact that these are educated guesses, rather than direct "confirmation" of the booster properties from the source.  As the quote indicates, the source seems to mildly contradict what our eyes and calculators tell us.
« Last Edit: 11/30/2015 12:09 am by cscott »

Offline Robotbeat

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Usually delta-v is fairly evenly split between first and second stages, with the second stage usually carrying a majority of the delta-v (because it has higher Isp, if only because it's in vacuum the whole time).

...but that's not the only possible way to do it. (Though for expendable vehicles, that's usually optimal.)

Blue Origin could decide to make the first stage a "pop-up" stage, where all it really does is provide a trip to vacuum for the vacuum upper stage, which acts nearly as a SSTO rocket, with, say, 7-9km/s of delta-v.

That's one interpretation of Jeff Bezos' statement that would let it be 100% correct, with the first stage taking nearly the same exact flight profile as what we just saw with New Shepard. It would technically be an RLV, but would practically be pretty much just an air-launched (or vacuum-launched, in this case) expendable SSTO rocket. Such a launch vehicle wouldn't have that great performance. Maybe competing with smaller Delta II-class or Soyuz-class payloads. Not really EELV or Falcon 9 territory.

Personally, I doubt that. I think the orbital Blue Origin vehicle will look a bit like what we saw previously, with multiple first stage engines around a single center engine. And that means a much higher performance first stage than New Shepard, a much more challenging trajectory. But it does mean competing with EELV class vehicles (like Falcon 9).
« Last Edit: 11/30/2015 12:52 am by Robotbeat »
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Offline a_langwich

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Your numbers are convincing, but I'm not sure how they are consistent with Bezos' statement:
Quote
“(For) our orbital plans, we’ve leased pad 36 at Cape Canaveral, and we’re building an orbital system, but the first stage — the booster stage of that — will be architecturally identical to the vehicle that we just flew because the environments and everything else are very, very similar, and having demonstrated that, we’ve basically validated that architecture with this flight,” he said.
http://spaceflightnow.com/2015/11/24/bezos-backed-blue-origin-achieves-rocket-landing/

A booster "built like a tank" is fundamentally incompatible with an orbital vehicle.  Much of that poor mass fraction seems to be visible to the naked eye in the form of ring fins, drag flaps, actuated front and aft guidance fins, and sturdy bacteriophage retractable legs.

So I'd personally tend to side with your numbers rather than Bezos here.  I'm just trying to maybe sure we keep straight the fact that these are educated guesses, rather than direct "confirmation" of the booster properties from the source.  As the quote indicates, the source seems to mildly contradict what our eyes and calculators tell us.


I don't think his "architecturally identical" means strictly identical, though it's not clear exactly what that means.  The presentation specifically mentions the orbital vehicle will use BE-4 and BE-3 engines, and it's not likely the first stage would use a small hydrolox BE-3 and the upper stage would use a (comparatively) giant methalox BE-4.  So at a minimum, he intends to swap in a BE-4 or two on the first stage.

Maybe he means he's going to try to use the same RTLS system (legs, ring fins and aft fins and drag brakes etc), and roughly similar altitude/speed range, but scaled up for the larger BE-4 thrust?  I don't think anything about the aerodynamics will just scale cleanly like that, and agree the rocket equation is going to be murder on an overheavy first stage at orbital dV, but perhaps (at least they can hope) it will be within reasonable adjustment range.  <waving hands furiously>    :)

They may also intend to extract a large amount of the mass penalty as they continue flying and testing the landing system.  It makes sense to overbuild the suborbital vehicle, since they can, and focus on getting it to work first and optimization later.

It will be fascinating to see this come together, and to see what they can accomplish.  Good luck to them!

Offline baldusi

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Plus, a longer and heavier first stage means proportionally a lot less aero losses, and improved pmf because you basically increase the lighter structure (the tank).
BTw, the ascent profile of the suborbital mission has a lot more gravity losses than an orbital mission. When flying straight up, you actually maximize your gravity losses. Which are proportional to the cosine of you angle to the gravity vector. Thus, orbital missions try to go horizontal as soon as possible.

Offline OxCartMark

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Perhaps it isn't built like a tank but rather lightly built and ballasted for its current use.  That would allow it to be architecturally the same but be able to be more efficient at orbital launch when its needed to be so.  ...Except that if this were the case then the non-ballasted orbital launch version would be so light on its return that it would need to do a hover slam landing, a future development.
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Offline Comga

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Plus, a longer and heavier first stage means proportionally a lot less aero losses, and improved pmf because you basically increase the lighter structure (the tank).
BTW, the ascent profile of the suborbital mission has a lot more gravity losses than an orbital mission. When flying straight up, you actually maximize your gravity losses. Which are proportional to the cosine of you angle to the gravity vector. Thus, orbital missions try to go horizontal as soon as possible.

BTW, Um....  Isn't it all gravity loss and aerodynamic loss in suborbital missions by definition, because it doesn't get to orbit?
In orbital launches these are the excess thrust reaction that doesn't go into the eventual orbital velocity.
In this case is doesn't matter what angle to the horizontal is chosen.  All the energy gets dissipated.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Comga

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Perhaps it isn't built like a tank but rather lightly built and ballasted for its current use.  That would allow it to be architecturally the same but be able to be more efficient at orbital launch when its needed to be so.  ...Except that if this were the case then the non-ballasted orbital launch version would be so light on its return that it would need to do a hover slam landing, a future development.

Perhaps this is Blue's way of doing incremental development.
First (or here second) flight has excess fuel that simulates the passengers and corresponding capsule equipment.  Because it is not jettisoned, it acts as ballast, allowing for hovering.
Over time Blue could shift the mass to the capsule, at the cost of having to land faster.
Eventually it becomes a hoverslam, which is more efficient but trickier.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline yg1968

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The BO test is significant because they've successfully been to space and thus have significantly more credibility that they will succeed and in the not too distant future.

It's 2004 all over again.

Not really. Spaceship 1 wasn't meant to carry tourists in space. Although, it's surprising that it's taken this long.

Offline LouScheffer

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Perhaps it isn't built like a tank but rather lightly built and ballasted for its current use.  That would allow it to be architecturally the same but be able to be more efficient at orbital launch when its needed to be so.  ...Except that if this were the case then the non-ballasted orbital launch version would be so light on its return that it would need to do a hover slam landing, a future development.
That's going to be one extreme hover-slam.  Falcon 9 cannot hover even at 5.4% of its takeoff thrust (1/9 of engines at 60%) power.  The Be-3 can throttle down to 18%.  Hydrogen vehicles can do with a less extreme mass fraction, but even so that's still several Gs up at minimum throttle.

Also arguing against a flight-weight but ballasted design is the ability to retract the legs.  That's nice for checkout, and rapid operations, but it surely costs mass.  I had a friend who complained about exactly this when pressed into service on an early cruise missile project.  The fins could be both unfolded and folded hydraulically.  But this costs mass for the intended operation (you test and fold them in the factory, drop them from the plane, then they pop out).  They were replaced with springs and latches.

I think it more likely this is a vehicle purpose-built for the sub-orbital market.   The need for a minimum mass would be a huge simplification for the engineering team, allowing the use of extra margin in place of super-detailed analysis.  The resulting vehicle would be more rugged and better suited for its intended role as a reusable carrier.

Offline savuporo

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I think it more likely this is a vehicle purpose-built for the sub-orbital market.   The need for a minimum mass would be a huge simplification for the engineering team, allowing the use of extra margin in place of super-detailed analysis.  The resulting vehicle would be more rugged and better suited for its intended role as a reusable carrier.
Exactly, there are enough challenges as there is in learning to operate a very first generation meaningfully reusable space rocket as an actual service to customers. Keep your margins until you really need them.
I'd buy a ticket much sooner if i knew they are flying with mass ratio of whopping 5, instead of 25.
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Offline QuantumG

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Not really. Spaceship 1 wasn't meant to carry tourists in space.

That's retroactive history. It was originally a requirement of the X-Prize that it do so.. and then it became merely a financial necessity.. and then a vague suggestion.. and then the old boy network figured out a way to give Paul his money back without having to fly and no-one has since. Bezos is already pushing their orbital plans, don't be surprised if New Shepard goes the same way.

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Offline Robotbeat

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The BO test is significant because they've successfully been to space and thus have significantly more credibility that they will succeed and in the not too distant future.

It's 2004 all over again.

Not really. Spaceship 1 wasn't meant to carry tourists in space. Although, it's surprising that it's taken this long.
Disagree. It was designed for 3 people. Sure, 2 were just sacks of potatoes, but the design was perfectly capable of carrying passengers. And that was, in fact, an option for them. They just chose to go directly to SS2 instead.

At least the SS1 flights were manned, quick turnaround, and had multiple flights to the Karman line for the same vehicle. Much more than can be said for New Shepard right now.
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Offline leaflion

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The BO test is significant because they've successfully been to space and thus have significantly more credibility that they will succeed and in the not too distant future.

It's 2004 all over again.

Not really. Spaceship 1 wasn't meant to carry tourists in space. Although, it's surprising that it's taken this long.
Disagree. It was designed for 3 people. Sure, 2 were just sacks of potatoes, but the design was perfectly capable of carrying passengers. And that was, in fact, an option for them. They just chose to go directly to SS2 instead.

At least the SS1 flights were manned, quick turnaround, and had multiple flights to the Karman line for the same vehicle. Much more than can be said for New Shepard right now.

Not sure if manned is necessarily a good thing, looking back at the last 1.1 years...

In my book Blue has got the right idea testing unmanned first.

Offline yg1968

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The BO test is significant because they've successfully been to space and thus have significantly more credibility that they will succeed and in the not too distant future.

It's 2004 all over again.

Not yet. They have to repeat it two times and then put it in a museum. :D

Pretty sure that never happened.  AFAIK the only thing Blue has in a museum is a little jet engine thing that they played with really early in company history.  I believe that only flew once, but its been a while since I visited the exhibit.

QuantumG and tobi were aluding to how SS1 was suppose to have changed everything with it's X-prize flights in 2004, where they flew three times and then retired to a museum. Unlike SS1 though, I think that New Shepherd is scaled properly so they can actually put it into operational service if it flies reliably enough. SS1 was always too much of a stunt plane for useful operational service. I'm not expecting the suborbital rocket nerd rapture to hit now, but I think the industry is about to become a lot more real (finally).

~Jon

This post belongs in this thread. I couldn't have said it better myself. I think that Blue's approach is different from SS1.
« Last Edit: 12/02/2015 04:21 am by yg1968 »

Offline Saabstory88

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That (4m) might be large. I took my original estimate, and compared it with an estimate which assumes a 12' diameter ring fin. From a volumetric perspective, these sizes work out nicely.

Great images, but I'm pretty confident that the LOX tank would be on top as you want the centre of mass to be as forward as possible to have the centre of gravity in front of the centre of pressure. This makes the vehicle more stable in flight, just like an arrowhead on an arrow does (with feathers/fins at the back to move the centre of pressure back).

I would have thought that to be the case, however, I made that choice based on the feed line labeling available in the first flight video. The LOX F/D line seems to be on the bottom of the vehicle, as you can clearly see the aft fin. The line which separates from the top of the stage appears to have a higher volume, which lead me to believe that this is the LH2 fill line. This is why I guessed at this configuration.

As an aside, they may care more about the arrowhead stability when the vehicle is free-falling un powered. This may be the reason for the large aero surfaces during ascent, to deal with this COM.

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