Author Topic: SpaceX Starship/Super Heavy Engineering General Thread 4  (Read 1621283 times)

Offline RamsesBic

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4260 on: 03/13/2023 10:19 pm »
Don't care about sailors and what not. I was wondering if workers have already been seen walking on the chopstick arms while they have been up. I can't recall seeing this, but maybe someone else has?

No, I haven't seen them do that. But that does not mean they would not if it is the best option.

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4261 on: 03/24/2023 01:41 am »
https://m.youtube.com/watch?v=G0lPF-O7B7U&embeds_euri=https%3A%2F%2Fforum.nasaspaceflight.com%2F&feature=emb_imp_woyt


ISTM that if the load needs to distribute around the slot and the QD plate they need arches. More stringers and built up bracing laminates will do as a workaround  for existing builds but long term, custom arch stampings will give more strength per unit weight.


For that matter, arches throughout the interstage, skirt (SS skirt too) and cargo space, would mass less than stringers of equivalent strength. Take the idea one step further and do two rows of arches base to base to form tall '0' shapes joined at the equator with reinforcing hoop rings top, middle and bottom. The bottom apex of each 0 shape on the skirt would align with a hold down clamp. Modify as required to accommodate QD, ejection slots, etc.


Stringers are a reasonable solution for rockets that are produced onesey-twosey. Custom load bearing stamping start working when you're serious about mass production.


Not yet, not yet, but soon...
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Offline clongton

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4262 on: 04/08/2023 09:47 pm »
Cross posting, by request, from the "SpaceX Starship : Texas Prototype(s) Thread 25 : Discussion", with some clarifying edits.

WRT the Starlink door, in my opinion it will remain horizontal. I'm a structural engineer (retired), and have dealt with many, many openings that interrupt an axial load path, and the solution is exactly the same regardless of the size of the opening or the magnitude of the load. Removing a piece of the airframe and replacing its structural integrity under compression/axial load is a relatively simple matter to address from a structural load point of view. There are 2 approaches to this; (1) reinforced opening and (2) structural insert:

Reinforced Opening

Step 1. Replace the material removed with a minimum of the same material, as the cubic area removed, and shaped as a doubler plate that surrounds the entire opening. More is stronger, up to a point, but must be at least equal, at a minimum, to the material removed. As the circumferential length of the opening increases then the depth of the doubler plate also increases to combat deformation. There are formulas to calculate minimum depth.

Step 2. If the opening interrupts axial structural members designed to carry axial loads then simply replace those members - on the door/covering - with identical structural members so that, while closed and under load, the load path remains uninterrupted. In this way, with the door closed, the overall structure will function identically as if there were no opening present at all. There is no need to divert any loads around the opening to compensate for the opening; the loads will simply continue on thru the closed door, along those axial structural members on the door that align with the ships internal axial structure, as if the door was not even there.

Structural Insert

Step 1:  In the area of the opening, remove a portion of the airframe, considerably larger than the required door or hatch and replace it with a solid piece of material, considerably thicker than the airframe skin;
_ 1A: Exterior - flush with the exterior of the hull/airframe
_ 1B: Interior - taper all around the insert with a 5:1 taper, from the inner surface of the airframe skin out to the thickness of the insert.
 
Step 2: Blend in the axial structural members along the taper to the insert.

Step 3: Build the hatch opening into this insert. The opening must not violate the 5:1 taper, but penetrate only the thicker material.

The structural insert, while less complex, is considerably stronger than the reinforced opening, but also adds considerable mass to the airframe. Choosing between the two (2) solutions above involves a lot of tradeoffs that I'm not prepared to discuss here. Leave that to SpaceX Structural Engineering.

So the problem is not the structural integrity of the opening at all. That has a fairly straightforward solution. The difficulty, if there actually is any**,  is the hinge and latching mechanisms. Those are the potential failure points - NOT the opening shape or orientation, and these should be fairly straightforward design approaches.

Of course the devil is always in the details but what I have outlined above is the correct way to properly compensate for a "hole" of material that is removed from a structure that will experience loads under compression, in this case, under axial load.

**Just saying. Remember, SpaceX has *NOT* actually said there is a problem here. It's just everyone's speculation.

Edited
« Last Edit: 04/08/2023 10:39 pm by clongton »
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Offline Vahe231991

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4263 on: 04/09/2023 03:45 am »
Found this interesting tweet regarding a potential stretched variant of the Starship:
https://twitter.com/TylerG1998/status/1644878801770278913

If Musk is to be believed, SpaceX may be in the early stages of conceptualizing a taller Starship version measuring over 420 feet tall, bigger than the Interplanetary Transport System proposal (the initial design study for the Starship).

Offline Zed_Noir

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4264 on: 04/09/2023 04:16 am »
https://twitter.com/TylerG1998/status/1644878801770278913

Quote from: Elon Musk on Tweeter
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And we need to add 3 more Raptor Vacuum engines, because itís inevitable
9:03 PM ∑ Apr 8, 2023

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4265 on: 04/09/2023 10:23 pm »
Found this interesting tweet regarding a potential stretched variant of the Starship:
https://twitter.com/TylerG1998/status/1644878801770278913

If Musk is to be believed, SpaceX may be in the early stages of conceptualizing a taller Starship version measuring over 420 feet tall, bigger than the Interplanetary Transport System proposal (the initial design study for the Starship).
I wouldnít think of it that way. Itíll just stretch over time like most launch vehicles, including especially Falcon 9.
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Offline InterestedEngineer

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4266 on: 04/09/2023 10:42 pm »
Found this interesting tweet regarding a potential stretched variant of the Starship:
https://twitter.com/TylerG1998/status/1644878801770278913

If Musk is to be believed, SpaceX may be in the early stages of conceptualizing a taller Starship version measuring over 420 feet tall, bigger than the Interplanetary Transport System proposal (the initial design study for the Starship).

An extra 10m is an extra 5 segments.  That's a lot more fuel.

Each segment weighs 1.6t, so along with 3x3 = 9t of RaptorVac engines the dry mass increases 17t and with 3t of extra landing fuel means non-payload mass to LEO increases by 20t.

OTOH, instead of 1200t of fuel, at 9m * 4.52 * pi * 0.8t/m3 = 570t of extra fuel to LEO, or 1770t of fuel total.

With 6.5 km/sec deltaV required to get to LEO from MECO and an exhaust velocity of 3.6km/sec that's a mass ratio of 6, so that's 350t to LEO, or about 200t of payload.

Reusable.

So those extra 5 rings and 3 raptor Vacs will double the payload to LEO.

That's going to allows Mars Injection boosts from LEO with only 3 refuelings, and only 9 refuelings to get a full load of fuel. 
« Last Edit: 04/09/2023 10:58 pm by InterestedEngineer »

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4267 on: 04/09/2023 10:49 pm »
Found this interesting tweet regarding a potential stretched variant of the Starship:

If Musk is to be believed, SpaceX may be in the early stages of conceptualizing a taller Starship version measuring over 420 feet tall, bigger than the Interplanetary Transport System proposal (the initial design study for the Starship).

An extra 10m is an extra 5 segments.  That's a lot more fuel.

Each segment weighs 1.6t, so along with 3x3 = 9t of RaptorVac engines the dry mass increases 17t and with 3t of extra landing fuel means non-payload mass to LEO increases by 20t.

OTOH, instead of 1200t of fuel, at 9m * 4.52 * pi * 0.8t/m3 = 570t of extra fuel to LEO, or 1770t of fuel total.

With 6.5 km/sec deltaV required to get to LEO and an exhaust velocity of 3.6km/sec that's a mass ratio of 6, so that's 370t to LEO, or about 220t of payload.

Reusable.

So those extra 5 rings and 3 raptor Vacs will double the payload to LEO.

That's going to allow Mars Injection boosts from LEO with only 3 refuelings, and only 8 refuelings to get a full load of fuel.

Would the Mechazilla need to be taller to incorporate this increase?  Might explain why the tower at Roberts Road hasn't been stacked yet (Just waiting for this change to occur)??
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Offline Asteroza

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4268 on: 04/09/2023 11:55 pm »
Found this interesting tweet regarding a potential stretched variant of the Starship:

If Musk is to be believed, SpaceX may be in the early stages of conceptualizing a taller Starship version measuring over 420 feet tall, bigger than the Interplanetary Transport System proposal (the initial design study for the Starship).

An extra 10m is an extra 5 segments.  That's a lot more fuel.

Each segment weighs 1.6t, so along with 3x3 = 9t of RaptorVac engines the dry mass increases 17t and with 3t of extra landing fuel means non-payload mass to LEO increases by 20t.

OTOH, instead of 1200t of fuel, at 9m * 4.52 * pi * 0.8t/m3 = 570t of extra fuel to LEO, or 1770t of fuel total.

With 6.5 km/sec deltaV required to get to LEO and an exhaust velocity of 3.6km/sec that's a mass ratio of 6, so that's 370t to LEO, or about 220t of payload.

Reusable.

So those extra 5 rings and 3 raptor Vacs will double the payload to LEO.

That's going to allow Mars Injection boosts from LEO with only 3 refuelings, and only 8 refuelings to get a full load of fuel.

Would the Mechazilla need to be taller to incorporate this increase?  Might explain why the tower at Roberts Road hasn't been stacked yet (Just waiting for this change to occur)??

Gonna need a bigger crane.

(queue Jaws meme)

Offline RamsesBic

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4269 on: 04/10/2023 12:14 am »
Found this interesting tweet regarding a potential stretched variant of the Starship:

If Musk is to be believed, SpaceX may be in the early stages of conceptualizing a taller Starship version measuring over 420 feet tall, bigger than the Interplanetary Transport System proposal (the initial design study for the Starship).

An extra 10m is an extra 5 segments.  That's a lot more fuel.

Each segment weighs 1.6t, so along with 3x3 = 9t of RaptorVac engines the dry mass increases 17t and with 3t of extra landing fuel means non-payload mass to LEO increases by 20t.

OTOH, instead of 1200t of fuel, at 9m * 4.52 * pi * 0.8t/m3 = 570t of extra fuel to LEO, or 1770t of fuel total.

With 6.5 km/sec deltaV required to get to LEO and an exhaust velocity of 3.6km/sec that's a mass ratio of 6, so that's 370t to LEO, or about 220t of payload.

Reusable.

So those extra 5 rings and 3 raptor Vacs will double the payload to LEO.

That's going to allow Mars Injection boosts from LEO with only 3 refuelings, and only 8 refuelings to get a full load of fuel.

Would the Mechazilla need to be taller to incorporate this increase?  Might explain why the tower at Roberts Road hasn't been stacked yet (Just waiting for this change to occur)??

Gonna need a bigger crane.

(queue Jaws meme)

The LR11000 can be extended to 220m if need be. Just a bit less with the weight of an extended ship.
https://www.liebherr.com/external/products/products-assets/6c575f4a-4e11-44fa-b0ae-763b375f437b/liebherr-235-lr-11000-td-235-03-defisr11-2020.pdf

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4270 on: 04/10/2023 12:45 am »
twitter.com/ringwatchers/status/1645068410240348160

Quote
Superheavyís grid fins are a key part of the vehicleís recovery hardware, but the perpetually extended state looks quite different compared to Falcon 9. Letís take a look at how these grid fins work and why they can stay extended at all times. (1/10)

📸 @RGVaerialphotos

https://twitter.com/ringwatchers/status/1645068479903547392

Quote
The 4 grid fins are arranged in a 120-60-120-60 pattern, unlike the equal spacing on Falcon 9. Elon stated in the first @erdayastronaut tour that they are positioned this way to increase pitch control, which is optimal for Superheavy. (2/10)

🖼️ @ChameleonCir

Quote
These grid fins can pivot freely, however, they are NOT able to fold down. Removing the folding system deletes the extra complexity and potential failure areas that may be introduced. (3/10)

🖼️ @ChameleonCir

https://twitter.com/ringwatchers/status/1645068729070354437

Quote
If we look at them from the top, we can see that they really are quite thin. During some portions of the flight, there may be drag produced that isnít optimal, however, SpaceX believes that the benefits outweigh the negatives. (4/10)

📸 @RGVaerialphotos

Quote
There have been 2 grid fin designs to date. The first debuted on B4 and was a 4x4 grid pattern. B7 introduced a new design with a tighter 6x6 grid. Both of these have been made of  welded steel unlike those cut from a single titanium block on Falcon 9 . (5/10)

🖼️ @ChameleonCir

https://twitter.com/ringwatchers/status/1645069035955015681

Quote
On the Boosterís forward dome, 4 electric motor assemblies and 4 pivoting points are placed on an L-channel to connect with the fins. This hardware is installed before stacking the Booster in the bays. (6/10)

📸 @RGVaerialphotos

Quote
Before we get into how the grid fins are actually moved, letís look at the fins themselves. The back side has 1 large pivot point in the middle and a smaller attachment point coming off of it to connect to the motor. (7/10)

📸 @CosmicalChief

https://twitter.com/ringwatchers/status/1645069264376791040

Quote
Once the grid fin is inserted into the Booster, the pivot point connects to the receptacle in the Booster and a curved component connects the motor assembly to the grid fin. When complete, the grid fins can be controlled freely. (8/10)

🖼️ @ChameleonCir

The fins have been tested on various occasions on
Quote
Booster 7, and this time-lapsed clip shows some of the tests that they get put through. Itís sort of similar to how the flaps on the Ships get tested periodically. (9/10)

🎥 @NASASpaceflight

https://twitter.com/ringwatchers/status/1645069477220958214

Quote
As we approach the first launch, hopefully, we get to see Booster 7 actually use these grid fins to control itself and steer toward the targeted splashdown zone, but no matter what, it will be quite a sight to see. (10/10)

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4271 on: 04/10/2023 01:59 am »
Found this interesting tweet regarding a potential stretched variant of the Starship:
https://twitter.com/TylerG1998/status/1644878801770278913

If Musk is to be believed, SpaceX may be in the early stages of conceptualizing a taller Starship version measuring over 420 feet tall, bigger than the Interplanetary Transport System proposal (the initial design study for the Starship).
I wouldnít think of it that way. Itíll just stretch over time like most launch vehicles, including especially Falcon 9.

This reminds me of the part in "Liftoff", where they are trying to launch the Falcon One and Elon is pestering the engineers about details for the Falcon Five design. He's always thinking far ahead. Starship Full-Thrust...
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Offline CrazySpace

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4272 on: 04/10/2023 08:24 am »
ok, but grid fins, are not used for booster flight guide path, right? Are not capables for that, I know are basically for hold booster vertical, right?
« Last Edit: 04/10/2023 08:25 am by CrazySpace »

Offline clongton

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4273 on: 04/10/2023 01:20 pm »
ok, but grid fins, are not used for booster flight guide path, right? Are not capables for that, I know are basically for hold booster vertical, right?

The purpose of the grid fins is to guide the booster on its return trajectory to the landing zone. They take over from the rcs thrusters once the vehicle is low enough in the atmosphere for them to become effective control surfaces. They have nothing to do with holding the booster vertical.
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Offline spacenut

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4274 on: 04/10/2023 01:38 pm »
The grid fins are strong enough to catch the booster using the chopsticks on the tower.  IF the booster is ever stretched, the chopsticks would have to be higher on the tower for catching. 

Catching the Starship is a completed different thing.  I would think they would land on a pad to begin with and then be transported back to the tower for stacking. 

If the booster can land back at the tower, it would save hours of transporting and lifting back on the pad, thus each booster may have several Starships to launch.  There will be far more Starships than boosters, human rated Starships, tanker Starships (probably the stretched versions), cargo only Starships.  Lunar only Starships, maybe a tanker Starship converted to a fuel depot by adding solar panels and refrigeration equipment as well as docking equipment. 

I repeat this information for new people coming on line. 

Offline joek

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4275 on: 04/10/2023 01:50 pm »
...
Catching the Starship is a completed different thing.  I would think they would land on a pad to begin with and then be transported back to the tower for stacking. 
...

Starship pad landing would require legs or ...? Have we seen any indication of such on later starships?

Offline rsdavis9

...
Catching the Starship is a completed different thing.  I would think they would land on a pad to begin with and then be transported back to the tower for stacking. 
...

Starship pad landing would require legs or ...? Have we seen any indication of such on later starships?

They could add legs, but I doubt it. Crashing on the pad (which is now much smaller) causes all kinds of problems with debris.
I think they will keep landing in the ocean until they are confident enough about the level of precision needed to land on the chopsticks.
In other words get booster catching reliable and routine and then try to catch starship. In the meantime I would expect legs for landing the starship just to test it out(legs) and be able to inspect the heat shield.
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Offline Redclaws

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4277 on: 04/10/2023 02:02 pm »
The grid fins are strong enough to catch the booster using the chopsticks on the tower.  IF the booster is ever stretched, the chopsticks would have to be higher on the tower for catching. 

Or the milk stool lowered.  10 meters might be a lot to ask in terms of how it would affect ground interactions with engine blast, but still, itís raised well above the ground now.  They could also dig.

I guess what Iím saying is launch tower modification isnít the only route, though it might be the most economical.

Offline spacenut

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4278 on: 04/10/2023 02:04 pm »
The legs they used were small and can easily be added to a landing Starship.  Like what was said, you don't want it to crash into the tower.  Also, it may have to be refurbished before stacking.  Landing on a pad, returned to a bay for refurbishments.  There might be some tiles missing or burned areas that would have to be replaced.  Then it could be returned to the tower to be launched again. 

SpaceX might have 10 Starships per booster all in que to be launched after refurbishment, depending on how long it takes to refurbish. 

Offline RamsesBic

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Re: SpaceX Starship/Super Heavy Engineering General Thread 4
« Reply #4279 on: 04/10/2023 02:06 pm »
...
Catching the Starship is a completed different thing.  I would think they would land on a pad to begin with and then be transported back to the tower for stacking. 
...

Starship pad landing would require legs or ...? Have we seen any indication of such on later starships?

They could add legs, but I doubt it. Crashing on the pad (which is now much smaller) causes all kinds of problems with debris.
I think they will keep landing in the ocean until they are confident enough about the level of precision needed to land on the chopsticks.
In other words get booster catching reliable and routine and then try to catch starship. In the meantime I would expect legs for landing the starship just to test it out(legs) and be able to inspect the heat shield.

I disagree. I think they will keep landing ships on water for some time after they have landed boosters on the chopsticks. The ships have a long way to go before they can get to the 1-2m level of precision they would need to have. But as always we can only wait and see.

Tags: musk Starship SpaceX 
 

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