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SpaceX Discussion Thread


Skylon

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6 hours ago, JoeSchmuckatelli said:

He can sell and license stuff from one company to the other, however - and that is perfectly legit. 

Yes, as long as it is at fair market value. Ideally in such a circumstance Musk would recuse himself from the process on both sides of the deal.

He would also start running into issues if Tesla were, for instance, to only sell motors to SpaceX and refuse to sell them to anyone else. That would be a strong signal that Musk was forcing the public company he runs to provide services for his private side venture.

A little searching on the web shows me that Tesla does in fact sell motors on the general market.

Like many other car manufacturers, you can buy "crate" motors from Tesla and install them in your own electric car.

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I was tempted to make another snark at 2020 still not letting go, but honestly - it was most probably caused by the desire to put SN9 on the launchpad ASAP.

In Poland we have sayings: "Make haste slowly." and "Haste is a bad advisor." Both are self-explanatory methinks.

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On 12/11/2020 at 11:00 PM, sevenperforce said:

Anything external only complicates TPS if you have to have a seam in the TPS. My model doesn't need a seam in the TPS.

Okay, here you go. I think this would actually work.

index.php?action=dlattach;topic=52460.0;

The "high heel" or "stiletto" has no hydraulics in it; just a spring and a crush core. The pistons on the outer fairings have hydraulics and crush cores. The only actuated part in the "stiletto" is the hinge itself. The pistons do all the auto-leveling and the springs in the "high heel" will compensate automatically.

This design can handle coming down on one leg, on two legs, lateral velocity -- anything. Everything that contacts the ground is safely tucked up inside the skirt until it needs to be deployed. No seam in the heat shield. 

Liked this idea, now you could put the large piston inside the hull, yes this will reduce the reach with 30-40 cm. 
With this design it looks a lot to me like the tips are primary to prevent Starship from tipping, the heal is that its designed to stand on. 
I say this is something we could run with. Let the large pistons be the main legs as in reaching the ground, but an knee and an piston, the extended legs has flexibility up to an point there they point upward at this point they try to hold as something is very wrong. 

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11 minutes ago, RCgothic said:

what was this all about. That... Does not look like good practice.

If nothing else, they must have learned that a couple of rolls of steel on one side isn't adequate to keep an entire Starship upright. With luck, we won't see an incident like this again.

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3 hours ago, magnemoe said:

Liked this idea, now you could put the large piston inside the hull, yes this will reduce the reach with 30-40 cm. 

The extension of the legs is limited by the clearance to the SL Raptor engine bells and their gimbal range. So trying to move anything else inside would seriously limit that. I don't think there's any harm in keeping the outer fairings; clearly this was contemplated by SpaceX early and so they've already done modeling for the heat shield and so forth.

3 hours ago, magnemoe said:

With this design it looks a lot to me like the tips are primary to prevent Starship from tipping, the heal is that its designed to stand on. 

Once landed, the heel can indeed bear the entire weight of Starship. But the "feet" do more than just prevent tipover; they transfer the primary dynamic load of landing to the hydraulic pistons to the fairings. The heels only need to bear the static load. A member designed to bear a dynamic load requires much finer properties, and so this way the hydraulic pistons don't have to be actuated other than along the intended load-bearing vector.

There would be minor refinements. Ultimately you'd have an intended design where the extended feet touch the ground first, transferring the dynamic load to the pistons like shock absorbers, and then coming to rest on the heels. Kind of like the way you land if you're jumping from a high place: you land on the balls of your feet and then come to rest on your heel.

3 hours ago, magnemoe said:

I say this is something we could run with. Let the large pistons be the main legs as in reaching the ground, but an knee and an piston, the extended legs has flexibility up to an point there they point upward at this point they try to hold as something is very wrong. 

I would like to see a way to transfer the load to the thrust puck, since that's the way the rest of the ship is designed. Maybe something like this:

extension.png

However, this carries two problems. First, you're going to have a huge bending moment on the extending leg at its weakest point. Second, there's really no shock-absorbing role for the external pistons here, because the extending leg doesn't have free rotation. And you can't add freedom of rotation without screwing up the extending leg design.

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On 12/7/2020 at 7:53 AM, Gargamel said:

I don't think so, it's too rhythmic, and this is during the burn, so it wouldn't be irrelevant.    (Clarifying: I'm referring to the second stage mylar shroud)

 

On 12/7/2020 at 12:15 PM, Deddly said:

I can't find the reference now, but Elon addressed the second stage "pulsing" on Twitter a while back. If I recall correctly, they aren't completely sure what it is

Yeah... it's still doing it.   

 

If there was an answer earlier in the thread, if somebody would kindly point it out.   Thanks. 

Edited by Gargamel
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