Blue Origin thread.

[darthgently]

4 hours ago, tater said:

Setting up a propellant depot is a good idea, but SpaceX is not using hydrolox. The trouble would be that the pad would need plumbing for that assuming a hydrolox payload was carried as cargo.

BO is using hydrolox under the assumption that water ice might someday lead to lunar propellants.

I was assuming a Starship tanker with a separate cargo tank  independent the ship's fuel tanks

[tater]

17 minutes ago, darthgently said:

I was assuming a Starship tanker with a separate cargo tank  independent the ship's fuel tanks

Still has to be filled right before launch.

[sevenperforce]

4 hours ago, tater said:

4 hours ago, sevenperforce said:

I would be very surprised if there was no gimbal at all.

The LM didn't gimbal.

The descent propulsion system engine had 6° of gimbal in pitch and yaw, with roll handled by the ascent propulsion system's roll control thrusters. Only the ascent propulsion system had no gimbal.

4 hours ago, tater said:

One thing I did forget is that the actual floor is well above the boom of the gold foil area.

So even with room for some gimbal, they could likely have a smaller loss since they won't need the largest dia of the engine bell to be the cut out. Only the part actually inside the crew area. Maybe they can only have a 1m pillar? Maybe smaller, and tapered.

There's some suggestion that the BE-7 has a bell gimbal with a fixed thrust chamber.

[tater]

24 minutes ago, sevenperforce said:

The descent propulsion system engine had 6° of gimbal in pitch and yaw, with roll handled by the ascent propulsion system's roll control thrusters. Only the ascent propulsion system had no gimbal.

Somehow I conflated the 2. Oops

Still, the cut out for 2-3 engines could be a frustum of a cone such that there is room at the exit end (~1.2m/engine, plus gimbal needs), but less room at the top.

[sevenperforce]

24 minutes ago, tater said:

Still, the cut out for 2-3 engines could be a frustum of a cone such that there is room at the exit end (~1.2m/engine, plus gimbal needs), but less room at the top.

Indeed. Made even more advantageous if the bell alone gimbals rather than the entire thrust structure.

[tater]

Be-7 throttles 10-60%, then 100%. Wonder if canting all out, and throttling down would mitigate the exhaust/regolith interaction. Aim for 0 descent rate high enough that ejecta is not a serious concern, then drop throttle and gimbal out to try and drop at a minimal sink the last few meters.

[darthgently]

19 minutes ago, tater said:

Be-7 throttles 10-60%, then 100%. Wonder if canting all out, and throttling down would mitigate the exhaust/regolith interaction. Aim for 0 descent rate high enough that ejecta is not a serious concern, then drop throttle and gimbal out to try and drop at a minimal sink the last few meters.

Decelerate to an RCS manageable decent rate several meters above the surface then touch down with RCS only.  With perhaps higher thrust aft RCS thrusters as required.  This is assuming aft RCS thrusters are part of multi horns higher up the lander I suppose

[tater]

Their RCS is hydrolox as well, BTW.

[tater]

 

[RCgothic]

That really is a vastly superior design.

With reusable landers we get refilling, depots, and transshipment of cargo, all key exploration techs. Plus obvious alternatives to the money pit that is SLS/Orion. Still finding it hard to get over how much a win this is.

Now for maximal effectiveness of refilling ops they just need to sort out their reusable second stage for New Glenn.

[sevenperforce]

3 hours ago, RCgothic said:

That really is a vastly superior design.

Putting the capsule at the bottom is very Kerbal, very New Space, and very clever.

I'm still unsure where the engines are. Can this be used to physically drop cargo pods, or would the vehicle need to land and offload cargo robotically?

3 hours ago, RCgothic said:

Now for maximal effectiveness of refilling ops they just need to sort out their reusable second stage for New Glenn.

Fingers crossed.

Re-entry from orbit is just an inherently hard problem. I'm not sure how they do it. The four options seem to be (1) the DC-X/FHUS concept, (2) the Starship body flap approach, (3) the Shuttle/X-37/Dream Chaser approach, and (4) the Stoke/Chrysler SERV approach. Number 4 clearly won't work for a New Glenn upper stage (unless they do a radical redesign and replace the BE-3Us with BE-7s), and you'd need separate landing engines for Numbers 1 and 2. So a winged, wheeled vehicle seems like the only possibility.

[tater]

1 hour ago, sevenperforce said:

Putting the capsule at the bottom is very Kerbal, very New Space, and very clever.

I'm still unsure where the engines are. Can this be used to physically drop cargo pods, or would the vehicle need to land and offload cargo robotica

Very 1970s.

The engines are pretty much the same I will bet, though the crew deck floor is at least 1m above the base, so I think less intrusion (as we discussed previously, maybe a frustum of a cone cutout).

Looks like the cargo mass is sorta theoretical—unless they go for the side rail system (saddlebag?), which would be awesome. Solves so many problems, since any reusable cargo system needs to be able to load cargo easily in orbit. Containerizing cargo FTW.

EDIT: I think the engines are in the center because the flairs that look like engine bell locations have all kinds of landing leg hardware. Don't think they are engines.

[sevenperforce]

It looks like they've switched over to a regeneratively cooled nozzle for BE-7:

 

[tater]

That was the image I used to guestimate the size of the nozzle (wall behind is cinderblock).

[sevenperforce]

I don't know that this has been posted before, although it's fairly old news.

The Blue Origin store is selling a t-shirt with engine dimensions:

If you go to the sale page and look closely, you can read the engine dimensions (given in height x diameter):

• BE-3PM: 115" x 27"
• BE-3U: 175" x 99"
• BE-4: 150" x 76"
• BE-7: 80" x 37"

Main takeaway: the BE-3U is a honking big engine. Bigger than the J-2, bigger than an RVac, and bigger than the largest RL-10s.  Unless I miss my guess it will be the largest upper-stage engine ever flown, whenever it finally flies.

[tater]

My estimate on the dia if the engines was off a little. I put the dia at 1.2m for Be-7, guess it is closer to 1m. Makes fitting them in the lander even easier.

Edited May 31, 2023 by tater

[Codraroll]

11 hours ago, sevenperforce said:

If you go to the sale page and look closely, you can read the engine dimensions (given in height x diameter):

What a missed opportunity for them to blur out the stats, so that space nerds would have to buy the T-shirts to get the numbers.

[darthgently]

4 hours ago, Codraroll said:

What a missed opportunity for them to blur out the stats, so that space nerds would have to buy the T-shirts to get the numbers.

Which brings up the possibility the readable numbers on the shirts are intentionally wrong just to mess with ppl

[sevenperforce]

1 hour ago, darthgently said:

Which brings up the possibility the readable numbers on the shirts are intentionally wrong just to mess with ppl

We know that the Blue Origin website labels something as a hydrogen pump which, if zoomed in on, clearly says oxygen pump. So the web/marketing team may be just wildly inaccurate in general.

16 hours ago, tater said:

My estimate on the dia if the engines was off a little. I put the dia at 1.2m for Be-7, guess it is closer to 1m. Makes fitting them in the lander even easier.

Can't remember if I said this before or not, but if they really are going with a nozzle-only gimbal (which is still a shocking choice for a regeneratively-cooled nozzle), then that also decreases the space required for gimbal authority.

Assuming 10° pitch and yaw authority (not necessarily representative; just picking a round number), an engine that is 80" x 37" will need a circle 60.2" in diameter to accommodate gimbal from the thrust structure at the top of the engine, but will need a circle of only 47.4" in diameter to accommodate gimbal from the nozzle:

When you think about a lander with where the engines are clustered with 2 or 3 in a line, that extra gimbal clearance starts to add up. So I can see why they would want to go with a throat gimbal for that reason. Throat gimbals also allow for slightly lower overall fixture weight since the engine load mount doesn't move (the mount still needs to be able to transfer the off-axis load; it just doesn't have to do so while also moving).

What's unclear is whether these advantages are worth the added complexity of running both cryogenic cooling loops AND superheated high-pressure rocket exhaust through a flexible throat.

 

 

[darthgently]

Total amateur here, but how important is laminar-ish flow through the throat?  Gimballing there seems even more complicated if that is a factor.  Then again if any losses are offset by other design gains then its still a win

Edit: I'm particularly thinking of hot spot issues at the join

Edited May 31, 2023 by darthgently

[sevenperforce]

8 minutes ago, darthgently said:

Total amateur here, but how important is laminar-ish flow through the throat?

The flow itself isn't laminar at the throat, but that IS the location of the choke point, with subsonic flow on one side and supersonic flow on the other side. And so it's the point of greatest temperature and pressure.

They might place the gimbal location just downstream of the throat, so there is a fixed portion of the nozzle and a gimbaling portion of the nozzle. That's a good trick, as Anakin would say. Still not a straightforward problem though.

[tater]

1 hour ago, sevenperforce said:

Can't remember if I said this before or not, but if they really are going with a nozzle-only gimbal (which is still a shocking choice for a regeneratively-cooled nozzle), then that also decreases the space required for gimbal authority.

Here ya go:

Gotta be in the center, aside from the struts going into the flared areas, the docking port and airlock are in the same places as the flared bits as well. Wonder how many engines they went with?

[Barzon]

If it helps, you can probably get a rough estimate for the dimensions of the habitat from this tweet, if it hasn't been posted already.

 

 

Edited May 31, 2023 by Barzon

[tater]

1 minute ago, Barzon said:

If it helps, you can probably get a rough estimate for the dimensions of the habitat from this tweet, if it hasn't been posted already.

The question is if this is the same vehicle.

[Barzon]

It's probably a safe assumption. If not, well, all we can do is wait for more information.