SpaceX Is Insane! Starship Flight 4 Campaign Continues! Mechazilla Catch Problems!

Secure your privacy with Surfshark! Enter coupon code FELIX for an extra 3 months free at surfshark.deals/felix What do you think? Are the Chopstick vibrations a serious concern? Let me know your opinion in the comments! :_WAISweet::_WAIHeart:

“One ping only” The hunt for Red October… awesome movie

I think the booster should do a hop to practice the catch, if it works great, lot's of data and they can repeat the maneuver to build confidence ahead of the real return to launchpad catch. If it goes wrong then at least there isn't a whole lot of additional velocity coming down on the launchpad and maybe they can crash somewhere designated. Either way I think a hop would be a good move.

Talk about risk someone is gonna go up in a Boeing starliner lol.

The vibrations look to me (I could be very wrong) like a classic robot arm control problem. The arm is sent to the intended position but overshoots and has to come back, but overshoots.... What you want the arm to do is smoothly approach the intended position and come to a stop at that position without overshooting. A similar problem occurs when a tank is traveling over uneven terrain and has to keep its main gun accurately aimed at a target. The solution is fairly well known and involves using laplace equation or even a simplification thereof to apply the correct 'smoothing' of the robot arm. In short it looks like a software problem to me rather than a mechanical one, and so should be relatively simples to fix.

I'm impressed that you know about PID controllers. but the chop stick controller needs something a bit more sophisticated. (PID is just a quick COTS solution for simple feedback systems, e.g. some sort of fluid level control in an industrial process) The chop sticks need to control position, velocity, and acceleration with accuracy. So they need at least a Type 3 controller. That means at least three integrators in series. But the hydraulic cylinder is an integrator (it's length is proportional to the accumulation of fluid inside it) so they only need two integrators implemented in hardware or software. Important note: The ringing we saw when they moved the arm quickly and stopped abruptly was probably INTENTIONAL. They could be trying to verity their model of the arm's transfer function. In other words, they are probably checking it's vibrational modes.

Tower 2 has short arms ?well it's kind of obvious it's going to be called T-Rex. I'm calling it- catchZilla and T-Rex

Instead of a landing tower, why not have a landing pit? It's a big cylindrical hole in the ground that's a little deeper than the height of the booster. The diameter can be wide enough so that there is a large target for the booster, which would reduce the likelihood of missing. The booster is caught by a circular aperture door at the top of the pit that closes in toward the center catching the booster as in descends. The door can be designed so that the central catching aperture can be offset to the side a bit depending on where the booster enters as the booster would not always be perfectly centered. In other words there would be built in adaptability. If the engines fail when landing, the booster explodes underground, minimizing damage to any surrounding infrastructure above ground. Even better, you can have an emergency carbon dioxide release system in the pit to smother the engines and prevent or greatly limit combustion thus reducing the explosive power of a hard landing. This system can activate once it's known that the landing engine isn't working as it should. It's also even possible to design some sort of cushioning system at the base of the pit to soften a hard landing - maybe with water or some kind of net or something.

The arm shaking was most definitely part of the test and measurement process, to see what vibration mode and its amplitude would be.

Those white square patches on the chopsticks, "could" be preliminary placement of a set of Load cell sensors on the chopstick arms. For measurements of forces during the catch or even during the stacking. You would like those forces nicely distributed and within the design limits.

The counter movement would turn the wiggle into a wobble (because the actuators are at the hinge point but the mass is further out). Probably still too much motion for the precision maneuver of a catch.

You forgot to mention the SR75 launch in Australia that took place early this morning. Of course, that launch was hardly covered, and it seemed very low profile, but it is still a rocket going to space

The whole thing is insane, it is like trying to catch a flying California Redwood tree right out of thin air

I am so excited for IFT-4!!!! I feel it coming around the corner as everything is almost ready for it!!!

Yes, the T-Rex move was iconic, but the headphone bopping was hysterical.

I would like to see them fast track the fabrication of the second launch tower so it is capable of catching the booster on the launch after this one. Mitigates risk of damage to their launch infrastructure. They don't need launch capability from that tower right now so the initial fabrication could be simplified and streamlined. When booster catches on the second tower work they could move the booster catch to the main tower and starship catches to the second tower. Keep the higher risk operations further from the launch infrastructure.

FYI, The crane is called Marvin because Elon loves the science fiction novel 'The Hitchhikers Guide to the Galaxy', and the dull robot is called Marvin.

The shorter arms means less mass so the arms can respond more quickly. The whole system has some springiness. But the unsprung mass is an unavoidable mass that will contribute to stresses on impact. Since the mass has to move on impact the lower the mass the lower the stresses on impact. Also the lower the delta-V the lower the stresses. Matching the speed of the arm with what it is catching reduces the delta-V which reduces stress. With all the testing SpaceX does I'm surprised they haven't unit tested this. Like, have a booster take off for about a few meters off the arms and catching it.

You guys are a total class act. Your #1 of 2 sources of information about space that I trust. :_WAIStarship::_WAIYouRock2:

The ‘you will probably be forgotten’ for booster 1060 got me. 😂