Comments by "ke6gwf - Ben Blackburn" (@ke6gwf) on "Scott Manley"
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@simongeard4824 I agree completely that redundant computers wouldn't solve this, and yes, it's an error checking issue, back to only looking at one data point (the MET clock), and ignoring all other data such as spatial position, UTC clock, or even internal data such as whether previous steps on the script had been run.
And yes, the more data you look at, the more likely it is that you will get a disagree error, but that's where redundancy comes in, but also, a disagree error means that SOMETHING is wrong, and you need to identify and correct it!
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@TROPtastic the difference is the character and focus of the owners.
One is looking like a Lex Luther, building companies designed to destroy competition, ignoring safety and humanity in the goal of making more money, and basically trying to keep growing into any market that they can control, and make lots of money. It's the ultimate selfish drive to control and take what you want,at whatever price to others.
Elon is driven by a desire to get humans to Mars, and open up space to whoever wants to go. He's spent his own fortune and is putting his time and energy into getting there, not because he wants to take over, but because he knows he can do it better and cheaper!
So I see a big difference between the two, and see SpaceX as opening space up, not taking over.
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@Imammk you just invalidated your own argument lol
Thrust is produced by the interaction of expanding and accelerating gasses against the walls of the combustion chamber and nozzle, causing thrust in opposite reaction to its acceleration.
So rocket thrust is ONLY produced in the nozzle, and in this case there are 4 nozzles producing thrust.
If it were an open cycle and the turbopump had its own nozzle, then you could say it produced thrust, but the turbopump only injects fuel into the combustion chamber, and produces no thrust on its own.
Yes, thrust is made possible by the turbopump, just as thrust is made possible by the fuel pump, but "thrust" on the rocket, ie, power production, is only produced by the 4 separate combustion chambers and nozzles, and so my original statement stands!
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Joe Chang , yes, like I said, gravity and magnetism were similar in that they both decay with distance, and I used magnetism as an example because it is something that we can feel and experiment with instead of just being an abstract theory.
As far as long distance radio data transmission, yes!
I am a Ham Radio operator, and also spent a few years in broadcast radio, including installing and tuning towers and the antennas on them, so I know a few things about the subject.
You need 2 things you need to get a signal that far.
A high gain antenna at each end, and an error correcting data format for when interference overpowers the signal briefly.
If you take 23 watts and put it into a standard whip antenna (like a car radio antenna for instance), that power is going to radiate in all directions equally, and so any one direction is only going to get a tiny fraction of that energy.
That is a zero gain antenna.
But if you modify they antenna a little bit, such as putting reflector elements behind it, or the ultimate, using a dish antenna, you can point all that energy in one direction, giving it "gain".
An old rooftop TV antenna is an example, having reflector elements behind the main element.
A parabolic dish antenna is the highest gain you can have basically, which is why it it used for satellite dishes and microwave telecommunications links etc.
So what they do for the deep space missions is have a parabolic dish antenna that is kept aimed back at earth, and then since the atmosphere attenuates radio waves, and there is a lot of rf interference on earth, they have a network of satellites called the Deep Space Network or something like that, and they have even bigger dish antennas pointed back, and the combination is enough to allow communication at those distances.
It is extremely slow, because the data rate has to be kept very low at those distances, but the signal gets through, and if some drops out, it gets resent.
Then the Deep Space Network satellite relays it back to the earth ground station.
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Scott, one thing I think you misunderstood is the radio communication issue.
On the teleconference they really tried to talk around the issue, but finally got asked enough times what the problem was that they very reluctantly said more than just "an elevated background noise floor in certain geographical areas".
From what I heard on the teleconference, they said it was a loss of communication with TDRS, probably because of cell towers.
Now, I am a radio guy, and I don't know exactly what system they had set up, but if it involved the TDRS satellite network, then it would either be a ground station uplink to TDRS, or a connection to a NASA TDRS ground station.
If they are communicating directly with the capsule, they wouldn't need TDRS, so I am guessing that it was a TDRS uplink site, probably something Boeing built especially for Starliner. And didn't test...
Cell towers broadcast relatively low power, and directed out horizontally, so they don't waste power aiming for the sky.
Ever try to send a text from a plane? Lol
You don't get reception even directly over a tower usually, because the lobe is horizontal.
So there's no way that a cell tower would reach a signal to LEO.
It's just not powerful enough.
So, if a cell tower caused interference, it was with ground based equipment, not space based.
And that means that they probably didn't design proper filters and interference rejection into the ground systems, which is standard practice for any radio system installed near possible interference sources.
In addition, if it was a ground station connecting to TDRS, then they could test it ahead of time, to verify it connected.
Oh, and certainly they would have known that they were using the same frequency band (or near harmonics of) the nearby cell towers, because that's part of a basic site survey, and that's all in the public FCC database.
So if cell towers indeed causes this interference, unless one of the cell transmitters had just gone nuclear and was pumping out highly elevated levels of noise and hadn't shut down yet, then it means that they didn't do a proper site survey, they didn't design the system with intermod and interference rejection and protection and filtration, they didn't test the system to see if there was a lot of noise from nearby frequencies, and didn't test the link to TDRS to make sure it was stable.
And if they messed up THAT badly, I understand why they REALLY didn't want to admit that cell towers had messed up their TDRS uplink lol
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@hawkdsl PayPal wasn't a failure. Tesla is far from bankruptcy and has been for quite some time now.
Falcon 9 was a great success, as was Crew Dragon. Starlink is in the early stages but is functioning beyond expectations because it's being done differently than any previous attempt (though even Elon says they are just trying to be the first that doesn't go bankrupt).
The Boring Company is still in prototype and testing phase, with only one system at the convention center currently in Beta testing mode.
Once it expands onto the Strip, and Vegas allows Driver Assist features to be turned on, it should show its potential a little better, but they haven't built the planned custom people mover that will make it work really well yet, so it looks pretty messy right now, but it will improve.
And the deal with T Mobile won't really increase profits much, because it requires a new satellite design, and very little data will be used, and T Mobile won't even be charging extra for it. So I don't think that it will have a big impact on SpaceX, but Elon likes doing things that make a difference, and it makes a big difference, even if not a big profit.
And Shotwell is there to support turning Elon's vision into reality, not to try to take control of the company from Elon. And she does a great job at it too!
But, for people who don't like Elon personally, of course they are going to try to avoid giving him any credit for what he's doing.
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@hawkdsl haters by their very nature get all the facts wrong.
He was not kicked out of PayPal, he was replaced as CEO just before it was sold to eBay.
I agree that SpaceX works so well because of Shotwell, which is exactly why Elon gave her the job, because they work well together, she keeps the company working smoothly so he can focus on developing new technologies. Without both of them SpaceX would not be what it is today.
And if you think that SpaceX could push technology so far without Elon, how come no one else is doing so well, and how come before Elon hired her, Shotwell was just a regular engineer and manager at her previous jobs, and didn't make any amazing progress on anything before joining Elon?
Elon certainly has a cult of personality, but acting like that's all he is shows a deep level of denial of the accomplishments he's made and how integral he is to the companies he starts and runs.
And countless engineers and scientists have testified how in awe they are at his grasp of engineering and science, and how quickly he learns new things.
People who have spent a lifetime studying a particular subject, and they are in a meeting with Elon deciding how to proceed on a project, and he asks the right questions to be able to understand the situation, and then makes a decision that turns out to be the right one.
There's a reason SpaceX and Tesla are the most popular places for engineers to work, because Elon has created an environment where engineers can shine and develop amazing things, and with few exceptions, the ones who have worked with Elon say he's a great engineer.
You seem not to understand what the T Mobile service is, or how it compares to Starlink broadband internet.
They will use the same satellite buss, but nothing else will be the same. It's literally an expansion pack bolted to the Starlink satellite.
Different antennas, different frequencies, different power levels, and different ground based hardware.
The T-mobile service will only work for slow low bandwidth text message transmission, and possibly eventually phone calls, literally turning the satellite into a cell tower in space as far as the phone knows.
Starlink broadband internet service on the other hand is a high bandwidth that provides faster internet service than most cable internet today, and works everywhere in the world (when the laser links are fully rolled out anyway.)
If you consider that must of the cruise lines and airlines working on using Starlink for data connections as a "niche" service, that's on you lol
Already it's what people across every country are clamoring to get if they live in the country, or half a mile past the end of the cable company internet cable that wants $30k to extend broadband to the house.
And as they expand converge to places like Africa and Australia and South America, where internet infrastructure is not built out to most of the country, they will become the primary or only provider of internet access to great swaths of the world.
I know lots of people up in Canada for instance that are snapping up Starlink because all they had before was slow access, or Direct TV type internet access which is nearly useless, and now they can have stable and high speed access for about the same price.
But the Starlink service is totally different from what T-mobile is talking about, because it requires a large antenna and receiver on the ground, and uses completely different frequencies than cell phones, so the T-mobile deal doesn't give SpaceX more or less access to customers, because the orbital cell tower will be accessed through the cell phone carrier, while the internet service will be through SpaceX directly.
So anyway, do your research if you want to sound like you know what you are talking about!
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I remember my dad talking about seeing the Echo satellite go overhead. He went on to program for and operate a couple of the early tube and transistor computers including the ERMA at BofA in LA, basically the original Online Banking, and what made the magnetic ink on checks a thing so it could read them automatically.
One fun story he told was that the computer developed a glitch, some circuit was going out and it would lock some board on the back end of the computer up, and the operator would have to get up from the control console and walk all the way around the racks, open a panel and flip a momentary reset toggle switch.
The GE technicians had looked at it and just gave the instructions to keep flipping the switch as needed, and didn't seem to be in a hurry to repair it, so late one night when my dad was working alone processing checks, the thing kept locking up, and he would have to walk around to the other side of the racks and flip the switch, then walk back to the console and hit Continue, and it was wasting a lot of time, so he grabbed a roll of string from the secretary's desk, tied one end on the reset switch, through a vent slot in the cover panel, and then ran it over the top of the racks and tied it to the console, so every time it froze up he could just pull the string and hit the restart button and lose very little processing time.
The next morning the manager gets into work and yells at him for the string dangling over the room, and my dad tells him how many minutes of processing time it saved that night by not having to walk back every time, and the manager simmered down.
Then the manager went and called GE, and very soon the tech came over a little red around the ears and replaced the faulty board!
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@sunside79334 , lightweight linear position sensor hydraulic cylinders are a very common off-the-shelf product, as are the linear sensor components for inclusion in a custom cylinder design.
It is one of the most preferred means to measure position, because it is completely protected from external interference or damage, unlike rotary shaft encoders or external scales.
Since this is being controlled by a computer, all you have to do is tell the computer what angle of grid fin equals what cylinder position.
If you did a rotary encoder on the shaft, you have to find space for it, add complexity to the shaft, either a disk mounted to the shaft, gears to operate a parallel axis rotary encoder, or try to fit 4 of them in the center between the end bearings and the shafts and the stage seperation cylinder, protect it from damage (it would need to be a high precision encoder, which means very tiny slits which are susceptible to debris clogging them leading to an incorrect reading), and adding additional components to the system.
Then you would have to put that data into the computer, which would have to count pulses and then calculate rotary position.
The linear approach prevents calibration errors or position error, because instead of counting clicks, it can tell what part of the sensor the piston is at.
No, having it built in to an existing component that very possibly is an off the shelf part, where it is protected from space and heat and debris is a very smart thing.
Also, if they wanted pressure sensors, they would need to have 2, one for each end of the cylinder since it is a double acting cylinder.
These would probably be mounted flanking the valve if they needed them, but they aren't dealing with high forces here, so they don't really need pressure sensing.
As for the plumbing, it is really simple.
On the lower left side, 2 metal lines come from the hydraulic pump. One is Pressure and one is Return. (the smaller one is Pressure)
They connect to 2 square manifold loops, a larger and a smaller, and then there are 4 sets of red hydraulic hoses coming off the 4 sides of the manifolds to the valves, which are mounted on the cylinders.
The reason for the square loop manifolds took me a second to figure out, but it is to smooth hydraulic flow and prevent pressure drops.
Each valve and cylinder is separately controlled, and as they cycle, the hydraulic flow needs vary widely, but since they tend to move in opposed pairs, with one extending while the other retracts, and it takes a lot more fluid to extend a cylinder then to retract it, by allowing fluid to go either direction around the loop, it allows fluid to bypass lower flow cylinders to get to the higher flow cylinders.
If it only went 3/4 of the way around, then the cylinder on the far end would be starved if 2 cylinders before it were in high flow demands.
So by adding a few inches of pipe and closing the loop, they were able to reduce the size of the manifold pipe, and avoid pressure drop issues. I call that genius!
There is no need to try to hydraulically synchronize cylinder pairs, because that is done through positive position feedback through the computer, and since it is flying the rocket with the fins, it does not always want them synchronized.
If they were hydraulically synchronized, you would see lines going directly between the cylinders.
So, I am also quite impressed with this design, because it is simple, and uses standard parts and systems that are well understood and reliable, except maybe for the hydraulic pump, which is probably some special helium driven gas over hydraulic unit, which always have problems lol
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