SpaceX Super Heavy Starship BFR Flight Test 4 acceleration / g dials

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I added 'g dials' to a SpaceX launch long ago ( • SpaceX launch with acc... ), hoping it's OK to reuse this video for the same purpose. I found this video on the VideoFromSpace channel: • Blastoff! SpaceX Stars...
My 'image matching' method struggled a bit with the level of transparency in the HUD, so the result is very noisy - sorry about that. 'g' is just the change in speed shown in the original video. It's always positive to make display a little simpler, but also because if you were seated inside the vehicles, that's the way you'd almost invariably 'feel' the speed change. There are no brakes - just flamey-end thrust!
FT4 Starship reentry and landing with 'g dial' is here: • SpaceX Starship Flight...
00:00 Liftoff 0.5g
01:00 Throttle bucket? 0.4g
01:06 "Max q" 0.5g - 1.6g
02:54 BECO 0.3g
03:00 hot stage - boostback 3g ship 0.5g - 1g
03:44 boostback shutdown
04:15 hot stage adapter jettison
06:21 view of top of booster - hot stage reappears 06:32?
06:44 booster high altitude terminal velocity? 0g
06:57 re-entry max q? 5.1g!
07:15 landing burn 5.1g
08:14 ship shutdown 3.6g - 0g

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27 июл 2024

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Комментарии : 62

@MAZZAR0TH 16 дней назад

Still waiting for this impenetrable firmament and flat earth to appear.

@Messier42-handle 11 дней назад

exactly lol, they dont even know where it is

@TJ-W 10 дней назад

Don’t hold your breath

@xersxo5460 12 дней назад

Super Heavy tanking and then casually putting out 5.1 Gs is insane😂 😤

@heirofspinoza813 17 дней назад

Thank you for sharing, always crazy to remember that the Saturn V got up to 3.8 g just before the S-IC separation. Instead the higher acceleration is relegated to the upper stage. Shows just how dissimilar these two rockets are in their approach with regard to reusability, engine efficiency, staging etc. Cheers!

@raptorwhite6468 5 дней назад

3.8 was nothing, Titan II could reach 7 Gs

@ThePhantomRocket 14 дней назад

who the hell calls it BFR still?

@fosstera 12 дней назад

honestly this is the only valid criticism in this comment section

@ThePhantomRocket 11 дней назад

@@fosstera well i'd also argue that the G meter doesn't account for gravity and is only raw acceleration but I'm too lazy for the math.

@GrapeFlavoredAntifreeze 9 дней назад

Are the actual G forces 1G higher? Because on the ground the G meter should be reading 1G, not zero, so when it lifts off, I assume what the vehicle is actually experiencing is 1.5G, not .5 G, and this would carry through the whole flight, correct?

@trs4u 9 дней назад

Yes and no! This 'g dial' is just the difference in the displayed speed divided by the time between changes, because that's all the 'data' I have from the video. It's not at all like an accelerometer in a phone or racing car. When the speed is increasing vertically upwards at "1 g indicated" like at 1:40 space-farer-you would experience 2g. Falling tail-first at increasing speed also "1g indicated" like at 6:47 space-farer-you would experience weightlessness. It's complicated by stuff like the orientation of the vessel, and by altitude as the Earth-attraction element decreases the further away ('higher up' for flerfers!) you are, and possibly also by centrifugal forces?

@JonathanSchrock 8 дней назад

Essentially, this is from the frame of reference of the earth, rather than the vehicle.

@jonathanmabardy 5 дней назад

Nice. I’m assuming you did it frame by frame. Did you do it manually or code something?

@trs4u 5 дней назад

@@jonathanmabardy a bit of to-and-fro this example was by cropping out a tile containing the speed digits, cropping each digit tile out of that, and then comparing to a set of 11 'good' prototype digits. It's code, but with quite a bit of run-check-tweak-run

@Samonie67 9 дней назад

you probably should've averaged the m/s2 readout because it's really annoying to read flickering numbers

@trs4u 9 дней назад

That display already includes a 'moving average'. It is annoying, isn't it? The method I use produces numbers all over the place, 30 frames per second. I'm considering uploading a comparison video using OCR instead (this is prototype-image-matching). I'm not convinced arbitrary smoothing would satisfy everyone - the 'corners' from motor restarts should probably remain as corners? I am working on improving it...

@jaypaint4855 9 дней назад

“And liftoff of the Big Falcon Rocket”

@nicepixels8076 11 дней назад

Hey just a question. Are the dials vectors. Cause I think you are just using speed for acceleration and not vector quantities.

@trs4u 11 дней назад

@@nicepixels8076 they're just 'speed difference'! Not even speed difference, but only the magnitude of speed difference. It's in the description. I'll add a title card next time I do this.

@fosstera 12 дней назад

neat!

@nedodo2380 15 дней назад

Nice work! Can you apply some smoothing to the data so that it doesn't jump around as much?

@trs4u 15 дней назад

Smoother output would have made a better video! I really want to see if I can improve on the extraction of the actual data - a lot of the 'noise' is incorrect digits being output by my recogniser. There is a 'moving average' in use, but there are corners in the input due to long-lived recognition failures ('5' = '6' errors were common) and thrust changes.

@wikjo3985 9 дней назад

can you do the same but with ship reentry?

@ArcturanMegadonkey 16 дней назад

what flew up at 6:32? almost looked like a flying saucer lol

@trs4u 16 дней назад

Some frozen condensation maybe? Things move so oddly out of the atmosphere compared to watching them fall or blow away near the ground.

@hightech9763 16 дней назад

it was the hot stage ring

@trs4u 16 дней назад

@@hightech9763yeah I think you could be right - there's next to no thrust between adapter jettison and this sighting, it would be following a very similar path?

@unapersonacualquiera4352 16 дней назад

@@trs4u yes it is the hot stage ring

@ArcturanMegadonkey 15 дней назад

@@hightech9763 ok thank you

@awesomefeldmanfamily 16 дней назад

This is totally sick! Can we also get a graph with the time / g force with time stamp in a picture?

@trs4u 16 дней назад

@@awesomefeldmanfamily I set out to do exactly that, but it took me so long to get clean enough data out of my image-matching method that I got fed up with it and uploaded short of the target! I should do that next time

@awesomefeldmanfamily 15 дней назад

@@trs4u I appreciate you spending the time to do it, it must have been so hard how did you do it? You just scanned every second of the video and extracted the data out of the speed and put it into a chart? That seems so hard what kind of software did you even use to do that?

@trs4u 15 дней назад

@@awesomefeldmanfamily There's a very long-winded explanation on an old video of mine. It's basically image-comparison, but my old code for doing this wasn't giving great results for this video. This time I generated 'prototype' image tiles using as close as possible a match for the font/size in the video, then took the best match for each frame and digit. There's a few minutes of manual tidy up for aliasing/bright backgrounds breaking the match, and then a final run generates the dials. I use ffmpeg to split/crop the video, and the rest is my own Java code.

@Da_Cap_i_Tan 15 дней назад

how can it be a successful splash down when it exploded and fell over?

@trs4u 15 дней назад

The target wasn't splashdown - that's how space vessels landing under parachutes sometimes finish. The target was 7:39 where it stops (0g) with engines still lit at zero metres above the water, to simulate coming to a halt on the chopsticks. The engines-off methane flame and falling into the water was post-success.

@fosstera 12 дней назад

because that's what happens when a rocket splashes down? The goal was to softly land on the water using its engines, and it did do that. After engine shutdown, the vehicle was subject to the whims of wind, water currents, and gravity, and so it fell over. When the top impacted, it exploded. It's successful because it did exactly what it was supposed to do. After landing, IF the vehicle survived they would sink it by shooting high velocity armor piercing rounds at it if it couldn't sink itself. It exploded, which was the more likely outcome, which took care of the sinking problem. Did you expect a 270 foot tall tube of air to stay upright in the water or something?

@TJ-W 10 дней назад

It didn’t explode. At least not before it fell over. What’s it supposed to do after splashdown? Just stand there? I’m sure you’ll find anything to complain about, though. Have fun with that.

@Sidorovich420 9 дней назад

Starship/Superheavy is not called BFR btw

@trs4u 9 дней назад

Maybe. It's always going to be BFR to me, even if someone makes a Ber FR. The design is an instant classic in my opinion.

@Sidorovich420 9 дней назад

@@trs4u Always good to be accurate tho

@katalantra 7 дней назад

Why is it showing 0.9gs at 5:30 for example for the booster? Shouldn’t it be 0gs? You do know that it is moving slightly inclined downward as you know its flying engines first and the video shows the angle in which the booster is compared to the ground… shouldn’t that be accountable?

@trs4u 7 дней назад

All the dial shows is rate of change of displayed speed. It might be possible to build altitude and rotation into a model to make a display more like an accelerometer. That's a job for someone else!

@katalantra 7 дней назад

@@trs4u gotcha! It may also just have been a complicated request! It’s still pretty close and especially when you have that in mind to see that the Booster apparently pulled 6gs even. That is amazing data! :)

@arielhartung4557 16 дней назад

Shouldn't 0.5g be 1.5g? Weightlessness is -1g?

@trs4u 16 дней назад

@@arielhartung4557 I'm inferring my 'g' from the change of "speed" in the video, so it probably isn't the 'g' you'd feel in your seat in Ship's cockpit, nor as a stowaway in the top of Booster. At liftoff and during landing it's certainly 1g short, it's 'hard to say' accurately anywhere else?

@thrillchaser9492 15 дней назад

WRONG...Zero is weightless... -1 gee would be pulling your face to the dash + gee's mash you into the seat

@trs4u 15 дней назад

@@thrillchaser9492 It depends on frame of reference. All I've got to go on is 'vehicle speed' in the video. Going straight up unpowered no drag, speed drops at around 1g, but that would 'feel' like weightlessness. Straight down unpowered no drag, speed would rise at 1g, and you'd feel weightless again. It's complicated! The gold standard for how it would 'feel' would probably be load cell data from seat supports?

@thrillchaser9492 15 дней назад

@@trs4u I'm sorry you are not educated enough to understand gravity. positive gees add weight negative gees make you lighter.. ZERO gees you float.. that is ZERO-G.. The G meter doesn't lie...lmao

@trs4u 15 дней назад

@thrillchaser9492 you're thinking of an accelerometer inside a vehicle. Like I said further up the thread, that's not the information I have. The 'g dial' in this video is not from a 'g meter'. It might be possible to combine the orientations of the vehicles and their altitudes with the speeds of the vehicles to get closer to what a 'g meter' would tell us, but that's not what I've done.

@ACDCROCKS135 12 дней назад

Your "G" meter is completely wrong. That sucks because I wish that you actually had the real telemetry showing G forces from the mission. Oh well... :(

@fosstera 12 дней назад

the "G" meter values are calculated by measuring the change in the number labeled speed over a period of time, which appears to be per-frame. It's not "wrong" per-se, but it is lacking important data like axis of acceleration, and doesn't take into account gravity or the source of acceleration. It's perfectly fine as a fun thing to look at and go "woah look it was pulling over 5 g's here!" and nothing more.

@trs4u 12 дней назад

That's what I said in the description. If I do this again, would a title card on the video saying that help?