SSC Tuatara Top Speed run apparently faked?
Discussion
harrylee1 said:
Reverse engineering the maths digs you an even deeper hole.
Now SSC have to show video footage showing they hit 331mph, at around 8,600rpm and in 6th gear. They need to show clear unedited footage with no sound editing.
They've probably hired a VFX company that's why it's taking so long
SSC Nervously loads Gran Turismo Sport engine developers kitNow SSC have to show video footage showing they hit 331mph, at around 8,600rpm and in 6th gear. They need to show clear unedited footage with no sound editing.
They've probably hired a VFX company that's why it's taking so long
Strudul said:
ch37 said:
The original design specification for the driver display had a maximum top speed reading of 301 because beyond our record run we never envisioned someone trying to go that fast!
This doesn't really make sense as surely the code just displays a number using a font. Maybe at 1000 it might fall over from the extra number, but unless each value is a separate image file, it shouldn't have any problems displaying all the way up to 999.Simply does not make sense to have a limit of 301, you could argue for 300, that might be plausible. But if you are simply displaying a number with 3 digits, then 999 would be the default limit.
To add code to specifically change the value to 301 if it is greater than 301 just sounds stupid.
And to anyone who asks why does it matter? It does matter, lying to people about things is not good form, and is becoming too normalised. People and Companies need to realise that it is not ok to tell lies and that they will be found out by people who use skepticism and critical thinking to look at and analyse any evidence and come up with the truth, whatever that is, whether people like it or not, it is still the truth.
Edited by Olivergt on Thursday 29th October 16:49
Olivergt said:
^^This
Simply does not make sense to have a limit of 301, you could argue for 300, that might be plausible. But if you are simply displaying a number with 3 digits, then 999 would be the default limit.
To add code to specifically change the value to 301 if it is greater than 301 just sounds stupid.
The only way I can think of it making sense is if it's a problem with the input and they reach maximum sensor frequency or something, 301 seems like a strangely round figure to run into that problem at but maybe it's possible. Simply does not make sense to have a limit of 301, you could argue for 300, that might be plausible. But if you are simply displaying a number with 3 digits, then 999 would be the default limit.
To add code to specifically change the value to 301 if it is greater than 301 just sounds stupid.
I cant see this being settled quickly. It took them 9 days to get the first video out and they're going to want to check the next one a bit more carefully. If it takes some time for them to make absolutely sure their next video is factually accurate it's probably for the best. If they can get a full package of data independently verified to go with it then even better, realistically that might take longer still.
If the record is legitimate the last thing they need to do is to rush something else out that raises more questions.
harrylee1 said:
Jeffrey Cheng owns a Koenigsegg and was present at the SSC 'world record' run on the day. He has knowledge that CIMA did not sell the new gear ratios to SSC.
https://hcfautoparts.com/cima
This video needs a lot of explaining:
https://www.youtube.com/watch?v=NOE-RTLercU&t=...
The car is not moving yet the speed shows 14mph (35 seconds in)
Around the 180mph mark the speed is going up but the rev counter doesn't seem to moving much. (1:09 and watch rev counter and speed for about 10 seconds).
+ Speedo is completely blanked, nothing at all, even if the speedo under/over reads, why not leave it on show, it should still be consistently under/over reading.
They have a lot of questions to answer, as a corporate entity you can't just around lying like this. At the very least it is morally wrong if not illegal (fraud or misrepresentation?).
https://www.youtube.com/watch?v=NOE-RTLercU&t=...
The car is not moving yet the speed shows 14mph (35 seconds in)
Around the 180mph mark the speed is going up but the rev counter doesn't seem to moving much. (1:09 and watch rev counter and speed for about 10 seconds).
+ Speedo is completely blanked, nothing at all, even if the speedo under/over reads, why not leave it on show, it should still be consistently under/over reading.
They have a lot of questions to answer, as a corporate entity you can't just around lying like this. At the very least it is morally wrong if not illegal (fraud or misrepresentation?).
Just did a calculation for the power required to be transmitted to a flat road at 331 mph to overcome drag and rolling resistance.
I used the following info:
Cd 0.314 (this includes the downforce component at 500 kph, as stated by SSC)
Crr 0.012 (estimate for wide tyres)
Weight 1823 kg including downforce
Frontal area 1.672 sq. m.
Air density 1.16 (28 degC at 1010 mb)
Velocity 147 m/s
It comes out to 1000 kW.
So it probably had enough power at the wheels to do it.
I used the following info:
Cd 0.314 (this includes the downforce component at 500 kph, as stated by SSC)
Crr 0.012 (estimate for wide tyres)
Weight 1823 kg including downforce
Frontal area 1.672 sq. m.
Air density 1.16 (28 degC at 1010 mb)
Velocity 147 m/s
It comes out to 1000 kW.
So it probably had enough power at the wheels to do it.
GT119 said:
Just did a calculation for the power required to be transmitted to a flat road at 331 mph to overcome drag and rolling resistance.
I used the following info:
Cd 0.314 (this includes the downforce component at 500 kph, as stated by SSC)
Crr 0.012 (estimate for wide tyres)
Weight 1823 kg including downforce
Frontal area 1.672 sq. m.
Air density 1.16 (28 degC at 1010 mb)
Velocity 147 m/s
It comes out to 1000 kW.
So it probably had enough power at the wheels to do it.
This seems more like a flex about you than the SSCI used the following info:
Cd 0.314 (this includes the downforce component at 500 kph, as stated by SSC)
Crr 0.012 (estimate for wide tyres)
Weight 1823 kg including downforce
Frontal area 1.672 sq. m.
Air density 1.16 (28 degC at 1010 mb)
Velocity 147 m/s
It comes out to 1000 kW.
So it probably had enough power at the wheels to do it.
Olivergt said:
This video needs a lot of explaining:
https://www.youtube.com/watch?v=NOE-RTLercU&t=...
The car is not moving yet the speed shows 14mph (35 seconds in)
Around the 180mph mark the speed is going up but the rev counter doesn't seem to moving much. (1:09 and watch rev counter and speed for about 10 seconds).
+ Speedo is completely blanked, nothing at all, even if the speedo under/over reads, why not leave it on show, it should still be consistently under/over reading.
They have a lot of questions to answer, as a corporate entity you can't just around lying like this. At the very least it is morally wrong if not illegal (fraud or misrepresentation?).
hahahahahaha. that's ridiculous. It's up to 24mph when he launches it off or something stupid like that. Just like a totally disconnected figure. That digital display is literally irrelevant. https://www.youtube.com/watch?v=NOE-RTLercU&t=...
The car is not moving yet the speed shows 14mph (35 seconds in)
Around the 180mph mark the speed is going up but the rev counter doesn't seem to moving much. (1:09 and watch rev counter and speed for about 10 seconds).
+ Speedo is completely blanked, nothing at all, even if the speedo under/over reads, why not leave it on show, it should still be consistently under/over reading.
They have a lot of questions to answer, as a corporate entity you can't just around lying like this. At the very least it is morally wrong if not illegal (fraud or misrepresentation?).
Super geeky but some clever guy over on Reddit has run a spectrograph analysis on the sound and highlighted even more inconsistencies, he later did an analysis on the sound of the Koenigsegg run and that matched perfectly to the claims, funny that. Given Robert Mitchell's recent Instagram Story post I'm guessing that's the subject of the next video.
Paste below:
[b]Below is a spectrogram / audio analysis of SSC's top speed run. Needless to say, this analysis also raises further questions about SSC's claims.
Throwaway for obvious reasons. Mods requested I post this here rather than create a new thread.
EDIT: Fixed an arithmetic mistake with gear ratios.
TLDR:
• Audio analysis from the video suggests the Tuatara shifted from 5 -> 6 at ~6900 RPM (not ~7700 as claimed). Additionally, RPM at VMAX appears to be ~7650 RPM (not ~8600 as claimed). This further confirms a mismatch between audio/video/telemetry.
• Low-frequency audio data may contain useful information about absolute vehicle speed. If the data is to be believed, top speed (based on the AUDIO) is approximately ~255 mph. This is not to suggest earlier video analysis is wrong. Rather, that the audio, video, and telemetry may ALL be different from one another - and that things are even weirder than previously believed. If this analysis is true, then either the final drive differs from what is claimed, or the gear ratios do.
Relevant Links:
• Onboard Video: Claimed SSC Top Speed World Record Run (Top Gear)
• Shmee150's Video re: SSC World Record
• Misha Charoudin's Video re: SSC World Record
• Motor Trend article including SSC statement
• Pastebin of Motor Trend article including SSC statement as of GMT 2:20, October 29, 2020
Background:
When an engine runs, the noise it produces has amplitude peaks at frequencies corresponding to the engine speed and its harmonics. Therefore it's possible to extract approximate engine speed data from an audio track of sufficient quality.
The conversion from units of audio frequency (Hz) to engine speed (RPM) is a factor 60. As the the Tuatara's redline is 8800 RPM, we expect the engine to produce primary frequencies below 150 Hz = 9000 RPM. However, analysis of the overtones (harmonics, integer multiples of the fundamental frequency) is sometimes easier than the fundamental frequency depending on the audio track involved. The first overtone is most relevant to this post - it has a conversion factor to RPM of 30 and thus we would not expect it to see the signal go beyond 300 Hz = 9000 RPM.
Before getting to the analysis, I would like to stress that this is speculative and simply a presentation of what the data appears to show. I am not making any accusations. Absent comprehensive telemetry data released by SSC, this video is one of the few things we have to work with and the goal of this post is to illustrate what that data appears to contain.
Engine Spectrogram:
1. A 0-300 Hz spectrogram of the audio (Hann window size of 32768), completely uncut from the video, looks like this. Many engine overtones are distinctly visible towards the start of the video. We will be looking at the first overtone as it is by far the most distinct. This first overtone begins at 50 Hz (1500 RPM idle) and is the distinct line visible across the entire spectrogram peaking at ~255 Hz. The fundamental tone is not loud enough to be "visible" for the first ~12 seconds, but appears around that point in time. At takeoff (~10s), the first overtone rumbles around, then rises to the first shift point at ~125 Hz, which is when we also see the first peak of the fundamental frequency (at ~62.5 Hz).
2. Due to excessive wind noise it's difficult to make out the fundamental during the top-speed run. Instead we look to the first overtone which tracks clearly the entire way.
3. At 1:00 is the final shift before the run begins. This happens at an overtone frequency of ~230 Hz or approx 6900 RPM. This disagrees with SSC's statement that the 5 -> 6 shift occurred at 7700 RPM. At 7700 RPM we would expect a frequency of around ~250 Hz, but the spectrogram does not seem to indicate any strong signal traces leading up to, or away from, a shift point at 250 Hz (though there are some splotches there). Yet, distinct traces are visible to either side of 250 Hz.
4. SSC has already stated the video and telemetry are from separate runs, this would seem to confirm this, as well as suggest that the audio is as well.
5. At 1:19 max engine speed is reached. This occurs at an overtone frequency of ~255 Hz or approx. 7650 RPM. This is within 5% of the engine speed (7300 RPM) estimated by Misha and Robert Mitchell in Misha's video linked above. This value differs substantially from SSC's claimed engine speed of 8600 RPM (from their recent statement), further suggesting the audio/video are not from the same run as the telemetry.
6. At no point during the entire video does engine speed fall within 1000 RPM of the claimed redline of 8800 RPM (to clarify, 8800 RPM is the redline, while 8600 RPM is the engine speed SSC claims to have reached at VMAX).
SPECULATION - Tire Spectrogram (Vehicle Velocity) - The following considers what is, at best, trace amounts of data. However I feel it is necessary to include for completeness.
1. Similarly to the engine, numerous other mechanical systems in the vehicle also give off fundamentals and overtones as they rotate. This includes road noise from wheels and tires. At particularly high speeds, any slight imperfections in these systems will appear at frequencies equal to their rotating speed (plus harmonics). Multiple things can cause this - for example, tiny imbalances in any of the wheels can manifest as road noise at speed.
2. Any audible signal from these components would be miniscule in comparison with engine noise. This, plus other factors (frequency near the lower cutoff of typical recording range, poor temporal resolution at low frequencies, etc) means the following spectrogram should be taken as speculation at best.
3. SSC cites a tire circumference of 89.125 inches, which is in line with the specified tire measurements and their higher-than-normal tire pressure. 330 mph is ~5800 inches per second, or an expected tire speed of ~65 rotations per second (~65 Hz signal, if any is visible).
4. We can look at the end of the video at the section after the driver has let off the throttle - when the engine noise is much lower and road noise is greater by comparison. The spectrogram here shows a dark trace dropping from ~50 Hz to ~25 Hz. It is not extremely sharp, but distinct enough to be sure something is there. Whether this trace indicates wheel speed is not clear.
5. If this trace is indeed caused by wheel speed, it is substantially far off from the 65 Hz frequency we'd expect to see if the vehicle were traveling 330 mph. (Note that the data are too noisy to say with certainty that there is not ALSO a trace coming from 65 Hz.)
6. By comparison, with a wheel of this size, wheel noise at a frequency of 50 Hz would equate to a vehicle speed of approximately ~255 mph, not 330 mph.
7. The Tuatara uses all seven gears - six during acceleration, plus a final upshift to 7th at the very end of the run. What are not clear are the actual gear ratios / final drive used in the car and whether they match the ratios in SSC's statement.
8. SSC's stated 5th gear top speed is 268 mph at 8800 RPM. In this gear, at 7650 RPM, the vehicle would travel only 234 mph. Using the claimed 6th gear ratio by comparison, it would travel 287 mph at this RPM. Both are a mismatch for the audio data suggesting 255 mph.
9. Please note that this calculated spectrogram speed also does not match the vehicle speed calculated in previous YouTube videos. This could suggest either the spectrogram analysis is incorrect (data too noisy, the trace is from another source, etc), that the audio and video are also mismatched, or something else is going on. In other words, it's within the realm of possibility that part or all of the analysis can't be trusted due to lack of more data. Or, it's possible I've made mistakes here. Finally, it's possible that the audio, video, and telemetry are all from separate runs, and that yes, the values claimed by SSC are disingenuous.
Steps to Replicate Analysis Yourself:
• Rip the audio from the YouTube world-record run video and import it to Audacity or an equivalent program (any program that offers spectrogram viewing)
• Change to "Spectrogram" mode (in Audacity, click the blue dropdown arrow to the left of the track)
• Adjust the Spectrogram Settings (in Audacity, again click the blue dropdown arrow -> "Spectrogram Settings"). Use Min Freq = 0 Hz, Max Freq = 300 Hz, and set a Hann Window Size of 32768[/b]
Paste below:
[b]Below is a spectrogram / audio analysis of SSC's top speed run. Needless to say, this analysis also raises further questions about SSC's claims.
Throwaway for obvious reasons. Mods requested I post this here rather than create a new thread.
EDIT: Fixed an arithmetic mistake with gear ratios.
TLDR:
• Audio analysis from the video suggests the Tuatara shifted from 5 -> 6 at ~6900 RPM (not ~7700 as claimed). Additionally, RPM at VMAX appears to be ~7650 RPM (not ~8600 as claimed). This further confirms a mismatch between audio/video/telemetry.
• Low-frequency audio data may contain useful information about absolute vehicle speed. If the data is to be believed, top speed (based on the AUDIO) is approximately ~255 mph. This is not to suggest earlier video analysis is wrong. Rather, that the audio, video, and telemetry may ALL be different from one another - and that things are even weirder than previously believed. If this analysis is true, then either the final drive differs from what is claimed, or the gear ratios do.
Relevant Links:
• Onboard Video: Claimed SSC Top Speed World Record Run (Top Gear)
• Shmee150's Video re: SSC World Record
• Misha Charoudin's Video re: SSC World Record
• Motor Trend article including SSC statement
• Pastebin of Motor Trend article including SSC statement as of GMT 2:20, October 29, 2020
Background:
When an engine runs, the noise it produces has amplitude peaks at frequencies corresponding to the engine speed and its harmonics. Therefore it's possible to extract approximate engine speed data from an audio track of sufficient quality.
The conversion from units of audio frequency (Hz) to engine speed (RPM) is a factor 60. As the the Tuatara's redline is 8800 RPM, we expect the engine to produce primary frequencies below 150 Hz = 9000 RPM. However, analysis of the overtones (harmonics, integer multiples of the fundamental frequency) is sometimes easier than the fundamental frequency depending on the audio track involved. The first overtone is most relevant to this post - it has a conversion factor to RPM of 30 and thus we would not expect it to see the signal go beyond 300 Hz = 9000 RPM.
Before getting to the analysis, I would like to stress that this is speculative and simply a presentation of what the data appears to show. I am not making any accusations. Absent comprehensive telemetry data released by SSC, this video is one of the few things we have to work with and the goal of this post is to illustrate what that data appears to contain.
Engine Spectrogram:
1. A 0-300 Hz spectrogram of the audio (Hann window size of 32768), completely uncut from the video, looks like this. Many engine overtones are distinctly visible towards the start of the video. We will be looking at the first overtone as it is by far the most distinct. This first overtone begins at 50 Hz (1500 RPM idle) and is the distinct line visible across the entire spectrogram peaking at ~255 Hz. The fundamental tone is not loud enough to be "visible" for the first ~12 seconds, but appears around that point in time. At takeoff (~10s), the first overtone rumbles around, then rises to the first shift point at ~125 Hz, which is when we also see the first peak of the fundamental frequency (at ~62.5 Hz).
2. Due to excessive wind noise it's difficult to make out the fundamental during the top-speed run. Instead we look to the first overtone which tracks clearly the entire way.
3. At 1:00 is the final shift before the run begins. This happens at an overtone frequency of ~230 Hz or approx 6900 RPM. This disagrees with SSC's statement that the 5 -> 6 shift occurred at 7700 RPM. At 7700 RPM we would expect a frequency of around ~250 Hz, but the spectrogram does not seem to indicate any strong signal traces leading up to, or away from, a shift point at 250 Hz (though there are some splotches there). Yet, distinct traces are visible to either side of 250 Hz.
4. SSC has already stated the video and telemetry are from separate runs, this would seem to confirm this, as well as suggest that the audio is as well.
5. At 1:19 max engine speed is reached. This occurs at an overtone frequency of ~255 Hz or approx. 7650 RPM. This is within 5% of the engine speed (7300 RPM) estimated by Misha and Robert Mitchell in Misha's video linked above. This value differs substantially from SSC's claimed engine speed of 8600 RPM (from their recent statement), further suggesting the audio/video are not from the same run as the telemetry.
6. At no point during the entire video does engine speed fall within 1000 RPM of the claimed redline of 8800 RPM (to clarify, 8800 RPM is the redline, while 8600 RPM is the engine speed SSC claims to have reached at VMAX).
SPECULATION - Tire Spectrogram (Vehicle Velocity) - The following considers what is, at best, trace amounts of data. However I feel it is necessary to include for completeness.
1. Similarly to the engine, numerous other mechanical systems in the vehicle also give off fundamentals and overtones as they rotate. This includes road noise from wheels and tires. At particularly high speeds, any slight imperfections in these systems will appear at frequencies equal to their rotating speed (plus harmonics). Multiple things can cause this - for example, tiny imbalances in any of the wheels can manifest as road noise at speed.
2. Any audible signal from these components would be miniscule in comparison with engine noise. This, plus other factors (frequency near the lower cutoff of typical recording range, poor temporal resolution at low frequencies, etc) means the following spectrogram should be taken as speculation at best.
3. SSC cites a tire circumference of 89.125 inches, which is in line with the specified tire measurements and their higher-than-normal tire pressure. 330 mph is ~5800 inches per second, or an expected tire speed of ~65 rotations per second (~65 Hz signal, if any is visible).
4. We can look at the end of the video at the section after the driver has let off the throttle - when the engine noise is much lower and road noise is greater by comparison. The spectrogram here shows a dark trace dropping from ~50 Hz to ~25 Hz. It is not extremely sharp, but distinct enough to be sure something is there. Whether this trace indicates wheel speed is not clear.
5. If this trace is indeed caused by wheel speed, it is substantially far off from the 65 Hz frequency we'd expect to see if the vehicle were traveling 330 mph. (Note that the data are too noisy to say with certainty that there is not ALSO a trace coming from 65 Hz.)
6. By comparison, with a wheel of this size, wheel noise at a frequency of 50 Hz would equate to a vehicle speed of approximately ~255 mph, not 330 mph.
7. The Tuatara uses all seven gears - six during acceleration, plus a final upshift to 7th at the very end of the run. What are not clear are the actual gear ratios / final drive used in the car and whether they match the ratios in SSC's statement.
8. SSC's stated 5th gear top speed is 268 mph at 8800 RPM. In this gear, at 7650 RPM, the vehicle would travel only 234 mph. Using the claimed 6th gear ratio by comparison, it would travel 287 mph at this RPM. Both are a mismatch for the audio data suggesting 255 mph.
9. Please note that this calculated spectrogram speed also does not match the vehicle speed calculated in previous YouTube videos. This could suggest either the spectrogram analysis is incorrect (data too noisy, the trace is from another source, etc), that the audio and video are also mismatched, or something else is going on. In other words, it's within the realm of possibility that part or all of the analysis can't be trusted due to lack of more data. Or, it's possible I've made mistakes here. Finally, it's possible that the audio, video, and telemetry are all from separate runs, and that yes, the values claimed by SSC are disingenuous.
Steps to Replicate Analysis Yourself:
• Rip the audio from the YouTube world-record run video and import it to Audacity or an equivalent program (any program that offers spectrogram viewing)
• Change to "Spectrogram" mode (in Audacity, click the blue dropdown arrow to the left of the track)
• Adjust the Spectrogram Settings (in Audacity, again click the blue dropdown arrow -> "Spectrogram Settings"). Use Min Freq = 0 Hz, Max Freq = 300 Hz, and set a Hann Window Size of 32768[/b]
Edited by honda_exige on Friday 30th October 15:44
Nice - i was waiting for someone to do something using the Audio. I had watched a video previously explaining the sound of a rotary engine as you add more rotars and how it ends up sounding like a high revving V12 and how you can work out the rpm from the sound.
Good stuff.
It all still seems remarkably silent from SSC.
RW
Good stuff.
It all still seems remarkably silent from SSC.
RW
Steven_RW said:
Nice - i was waiting for someone to do something using the Audio. I had watched a video previously explaining the sound of a rotary engine as you add more rotars and how it ends up sounding like a high revving V12 and how you can work out the rpm from the sound.
Good stuff.
It all still seems remarkably silent from SSC.
RW
Yeah I found it pretty fascinating. Given this guy on Reddit used a throwaway account "for obvious reasons" I guess he maybe works for a rival, Bugatti or Koenigsegg? Good stuff.
It all still seems remarkably silent from SSC.
RW
I remember F1 using this method, both for traction control when it was banned (microphones on the car retarded power based on audio analysis of engine note) and also other teams analysing each others engine notes to deduce what they're revving to, knowing how fast they're going and working out bhp etc
Edited by honda_exige on Friday 30th October 18:05
honda_exige said:
Super geeky but some clever guy over on Reddit has run a spectrograph analysis on the sound and highlighted even more inconsistencies, he later did an analysis on the sound of the Koenigsegg run and that matched perfectly to the claims, funny that. Given Robert Mitchell's recent Instagram Story post I'm guessing that's the subject of the next video.
Paste below:
[b]Below is a spectrogram / audio analysis of SSC's top speed run. Needless to say, this analysis also raises further questions about SSC's claims.
Throwaway for obvious reasons. Mods requested I post this here rather than create a new thread.
EDIT: Fixed an arithmetic mistake with gear ratios.
TLDR:
• Audio analysis from the video suggests the Tuatara shifted from 5 -> 6 at ~6900 RPM (not ~7700 as claimed). Additionally, RPM at VMAX appears to be ~7650 RPM (not ~8600 as claimed). This further confirms a mismatch between audio/video/telemetry.
• Low-frequency audio data may contain useful information about absolute vehicle speed. If the data is to be believed, top speed (based on the AUDIO) is approximately ~255 mph. This is not to suggest earlier video analysis is wrong. Rather, that the audio, video, and telemetry may ALL be different from one another - and that things are even weirder than previously believed. If this analysis is true, then either the final drive differs from what is claimed, or the gear ratios do.
Relevant Links:
• Onboard Video: Claimed SSC Top Speed World Record Run (Top Gear)
• Shmee150's Video re: SSC World Record
• Misha Charoudin's Video re: SSC World Record
• Motor Trend article including SSC statement
• Pastebin of Motor Trend article including SSC statement as of GMT 2:20, October 29, 2020
Background:
When an engine runs, the noise it produces has amplitude peaks at frequencies corresponding to the engine speed and its harmonics. Therefore it's possible to extract approximate engine speed data from an audio track of sufficient quality.
The conversion from units of audio frequency (Hz) to engine speed (RPM) is a factor 60. As the the Tuatara's redline is 8800 RPM, we expect the engine to produce primary frequencies below 150 Hz = 9000 RPM. However, analysis of the overtones (harmonics, integer multiples of the fundamental frequency) is sometimes easier than the fundamental frequency depending on the audio track involved. The first overtone is most relevant to this post - it has a conversion factor to RPM of 30 and thus we would not expect it to see the signal go beyond 300 Hz = 9000 RPM.
Before getting to the analysis, I would like to stress that this is speculative and simply a presentation of what the data appears to show. I am not making any accusations. Absent comprehensive telemetry data released by SSC, this video is one of the few things we have to work with and the goal of this post is to illustrate what that data appears to contain.
Engine Spectrogram:
1. A 0-300 Hz spectrogram of the audio (Hann window size of 32768), completely uncut from the video, looks like this. Many engine overtones are distinctly visible towards the start of the video. We will be looking at the first overtone as it is by far the most distinct. This first overtone begins at 50 Hz (1500 RPM idle) and is the distinct line visible across the entire spectrogram peaking at ~255 Hz. The fundamental tone is not loud enough to be "visible" for the first ~12 seconds, but appears around that point in time. At takeoff (~10s), the first overtone rumbles around, then rises to the first shift point at ~125 Hz, which is when we also see the first peak of the fundamental frequency (at ~62.5 Hz).
2. Due to excessive wind noise it's difficult to make out the fundamental during the top-speed run. Instead we look to the first overtone which tracks clearly the entire way.
3. At 1:00 is the final shift before the run begins. This happens at an overtone frequency of ~230 Hz or approx 6900 RPM. This disagrees with SSC's statement that the 5 -> 6 shift occurred at 7700 RPM. At 7700 RPM we would expect a frequency of around ~250 Hz, but the spectrogram does not seem to indicate any strong signal traces leading up to, or away from, a shift point at 250 Hz (though there are some splotches there). Yet, distinct traces are visible to either side of 250 Hz.
4. SSC has already stated the video and telemetry are from separate runs, this would seem to confirm this, as well as suggest that the audio is as well.
5. At 1:19 max engine speed is reached. This occurs at an overtone frequency of ~255 Hz or approx. 7650 RPM. This is within 5% of the engine speed (7300 RPM) estimated by Misha and Robert Mitchell in Misha's video linked above. This value differs substantially from SSC's claimed engine speed of 8600 RPM (from their recent statement), further suggesting the audio/video are not from the same run as the telemetry.
6. At no point during the entire video does engine speed fall within 1000 RPM of the claimed redline of 8800 RPM (to clarify, 8800 RPM is the redline, while 8600 RPM is the engine speed SSC claims to have reached at VMAX).
SPECULATION - Tire Spectrogram (Vehicle Velocity) - The following considers what is, at best, trace amounts of data. However I feel it is necessary to include for completeness.
1. Similarly to the engine, numerous other mechanical systems in the vehicle also give off fundamentals and overtones as they rotate. This includes road noise from wheels and tires. At particularly high speeds, any slight imperfections in these systems will appear at frequencies equal to their rotating speed (plus harmonics). Multiple things can cause this - for example, tiny imbalances in any of the wheels can manifest as road noise at speed.
2. Any audible signal from these components would be miniscule in comparison with engine noise. This, plus other factors (frequency near the lower cutoff of typical recording range, poor temporal resolution at low frequencies, etc) means the following spectrogram should be taken as speculation at best.
3. SSC cites a tire circumference of 89.125 inches, which is in line with the specified tire measurements and their higher-than-normal tire pressure. 330 mph is ~5800 inches per second, or an expected tire speed of ~65 rotations per second (~65 Hz signal, if any is visible).
4. We can look at the end of the video at the section after the driver has let off the throttle - when the engine noise is much lower and road noise is greater by comparison. The spectrogram here shows a dark trace dropping from ~50 Hz to ~25 Hz. It is not extremely sharp, but distinct enough to be sure something is there. Whether this trace indicates wheel speed is not clear.
5. If this trace is indeed caused by wheel speed, it is substantially far off from the 65 Hz frequency we'd expect to see if the vehicle were traveling 330 mph. (Note that the data are too noisy to say with certainty that there is not ALSO a trace coming from 65 Hz.)
6. By comparison, with a wheel of this size, wheel noise at a frequency of 50 Hz would equate to a vehicle speed of approximately ~255 mph, not 330 mph.
7. The Tuatara uses all seven gears - six during acceleration, plus a final upshift to 7th at the very end of the run. What are not clear are the actual gear ratios / final drive used in the car and whether they match the ratios in SSC's statement.
8. SSC's stated 5th gear top speed is 268 mph at 8800 RPM. In this gear, at 7650 RPM, the vehicle would travel only 234 mph. Using the claimed 6th gear ratio by comparison, it would travel 287 mph at this RPM. Both are a mismatch for the audio data suggesting 255 mph.
9. Please note that this calculated spectrogram speed also does not match the vehicle speed calculated in previous YouTube videos. This could suggest either the spectrogram analysis is incorrect (data too noisy, the trace is from another source, etc), that the audio and video are also mismatched, or something else is going on. In other words, it's within the realm of possibility that part or all of the analysis can't be trusted due to lack of more data. Or, it's possible I've made mistakes here. Finally, it's possible that the audio, video, and telemetry are all from separate runs, and that yes, the values claimed by SSC are disingenuous.
Steps to Replicate Analysis Yourself:
• Rip the audio from the YouTube world-record run video and import it to Audacity or an equivalent program (any program that offers spectrogram viewing)
• Change to "Spectrogram" mode (in Audacity, click the blue dropdown arrow to the left of the track)
• Adjust the Spectrogram Settings (in Audacity, again click the blue dropdown arrow -> "Spectrogram Settings"). Use Min Freq = 0 Hz, Max Freq = 300 Hz, and set a Hann Window Size of 32768[/b]
Nice bit of forensics there, but I fear Pommy bogan might blow an o-ring with all that data you presented.Paste below:
[b]Below is a spectrogram / audio analysis of SSC's top speed run. Needless to say, this analysis also raises further questions about SSC's claims.
Throwaway for obvious reasons. Mods requested I post this here rather than create a new thread.
EDIT: Fixed an arithmetic mistake with gear ratios.
TLDR:
• Audio analysis from the video suggests the Tuatara shifted from 5 -> 6 at ~6900 RPM (not ~7700 as claimed). Additionally, RPM at VMAX appears to be ~7650 RPM (not ~8600 as claimed). This further confirms a mismatch between audio/video/telemetry.
• Low-frequency audio data may contain useful information about absolute vehicle speed. If the data is to be believed, top speed (based on the AUDIO) is approximately ~255 mph. This is not to suggest earlier video analysis is wrong. Rather, that the audio, video, and telemetry may ALL be different from one another - and that things are even weirder than previously believed. If this analysis is true, then either the final drive differs from what is claimed, or the gear ratios do.
Relevant Links:
• Onboard Video: Claimed SSC Top Speed World Record Run (Top Gear)
• Shmee150's Video re: SSC World Record
• Misha Charoudin's Video re: SSC World Record
• Motor Trend article including SSC statement
• Pastebin of Motor Trend article including SSC statement as of GMT 2:20, October 29, 2020
Background:
When an engine runs, the noise it produces has amplitude peaks at frequencies corresponding to the engine speed and its harmonics. Therefore it's possible to extract approximate engine speed data from an audio track of sufficient quality.
The conversion from units of audio frequency (Hz) to engine speed (RPM) is a factor 60. As the the Tuatara's redline is 8800 RPM, we expect the engine to produce primary frequencies below 150 Hz = 9000 RPM. However, analysis of the overtones (harmonics, integer multiples of the fundamental frequency) is sometimes easier than the fundamental frequency depending on the audio track involved. The first overtone is most relevant to this post - it has a conversion factor to RPM of 30 and thus we would not expect it to see the signal go beyond 300 Hz = 9000 RPM.
Before getting to the analysis, I would like to stress that this is speculative and simply a presentation of what the data appears to show. I am not making any accusations. Absent comprehensive telemetry data released by SSC, this video is one of the few things we have to work with and the goal of this post is to illustrate what that data appears to contain.
Engine Spectrogram:
1. A 0-300 Hz spectrogram of the audio (Hann window size of 32768), completely uncut from the video, looks like this. Many engine overtones are distinctly visible towards the start of the video. We will be looking at the first overtone as it is by far the most distinct. This first overtone begins at 50 Hz (1500 RPM idle) and is the distinct line visible across the entire spectrogram peaking at ~255 Hz. The fundamental tone is not loud enough to be "visible" for the first ~12 seconds, but appears around that point in time. At takeoff (~10s), the first overtone rumbles around, then rises to the first shift point at ~125 Hz, which is when we also see the first peak of the fundamental frequency (at ~62.5 Hz).
2. Due to excessive wind noise it's difficult to make out the fundamental during the top-speed run. Instead we look to the first overtone which tracks clearly the entire way.
3. At 1:00 is the final shift before the run begins. This happens at an overtone frequency of ~230 Hz or approx 6900 RPM. This disagrees with SSC's statement that the 5 -> 6 shift occurred at 7700 RPM. At 7700 RPM we would expect a frequency of around ~250 Hz, but the spectrogram does not seem to indicate any strong signal traces leading up to, or away from, a shift point at 250 Hz (though there are some splotches there). Yet, distinct traces are visible to either side of 250 Hz.
4. SSC has already stated the video and telemetry are from separate runs, this would seem to confirm this, as well as suggest that the audio is as well.
5. At 1:19 max engine speed is reached. This occurs at an overtone frequency of ~255 Hz or approx. 7650 RPM. This is within 5% of the engine speed (7300 RPM) estimated by Misha and Robert Mitchell in Misha's video linked above. This value differs substantially from SSC's claimed engine speed of 8600 RPM (from their recent statement), further suggesting the audio/video are not from the same run as the telemetry.
6. At no point during the entire video does engine speed fall within 1000 RPM of the claimed redline of 8800 RPM (to clarify, 8800 RPM is the redline, while 8600 RPM is the engine speed SSC claims to have reached at VMAX).
SPECULATION - Tire Spectrogram (Vehicle Velocity) - The following considers what is, at best, trace amounts of data. However I feel it is necessary to include for completeness.
1. Similarly to the engine, numerous other mechanical systems in the vehicle also give off fundamentals and overtones as they rotate. This includes road noise from wheels and tires. At particularly high speeds, any slight imperfections in these systems will appear at frequencies equal to their rotating speed (plus harmonics). Multiple things can cause this - for example, tiny imbalances in any of the wheels can manifest as road noise at speed.
2. Any audible signal from these components would be miniscule in comparison with engine noise. This, plus other factors (frequency near the lower cutoff of typical recording range, poor temporal resolution at low frequencies, etc) means the following spectrogram should be taken as speculation at best.
3. SSC cites a tire circumference of 89.125 inches, which is in line with the specified tire measurements and their higher-than-normal tire pressure. 330 mph is ~5800 inches per second, or an expected tire speed of ~65 rotations per second (~65 Hz signal, if any is visible).
4. We can look at the end of the video at the section after the driver has let off the throttle - when the engine noise is much lower and road noise is greater by comparison. The spectrogram here shows a dark trace dropping from ~50 Hz to ~25 Hz. It is not extremely sharp, but distinct enough to be sure something is there. Whether this trace indicates wheel speed is not clear.
5. If this trace is indeed caused by wheel speed, it is substantially far off from the 65 Hz frequency we'd expect to see if the vehicle were traveling 330 mph. (Note that the data are too noisy to say with certainty that there is not ALSO a trace coming from 65 Hz.)
6. By comparison, with a wheel of this size, wheel noise at a frequency of 50 Hz would equate to a vehicle speed of approximately ~255 mph, not 330 mph.
7. The Tuatara uses all seven gears - six during acceleration, plus a final upshift to 7th at the very end of the run. What are not clear are the actual gear ratios / final drive used in the car and whether they match the ratios in SSC's statement.
8. SSC's stated 5th gear top speed is 268 mph at 8800 RPM. In this gear, at 7650 RPM, the vehicle would travel only 234 mph. Using the claimed 6th gear ratio by comparison, it would travel 287 mph at this RPM. Both are a mismatch for the audio data suggesting 255 mph.
9. Please note that this calculated spectrogram speed also does not match the vehicle speed calculated in previous YouTube videos. This could suggest either the spectrogram analysis is incorrect (data too noisy, the trace is from another source, etc), that the audio and video are also mismatched, or something else is going on. In other words, it's within the realm of possibility that part or all of the analysis can't be trusted due to lack of more data. Or, it's possible I've made mistakes here. Finally, it's possible that the audio, video, and telemetry are all from separate runs, and that yes, the values claimed by SSC are disingenuous.
Steps to Replicate Analysis Yourself:
• Rip the audio from the YouTube world-record run video and import it to Audacity or an equivalent program (any program that offers spectrogram viewing)
• Change to "Spectrogram" mode (in Audacity, click the blue dropdown arrow to the left of the track)
• Adjust the Spectrogram Settings (in Audacity, again click the blue dropdown arrow -> "Spectrogram Settings"). Use Min Freq = 0 Hz, Max Freq = 300 Hz, and set a Hann Window Size of 32768[/b]
Edited by honda_exige on Friday 30th October 15:44
Condi said:
Surely you just ask them to repeat it with independent witness or different logging gear?
It's hardly rocket science. If it can do it once, it can do it twice.
I understand the perspective but there are risks every time you go for the limit and no brand wants to be associated with the fallout of a major crash and a dead test pilot. So achieving your aim with the minimum attempts has to be desirable. The idea of plucking up tbe courage again probably isn't that attractive in terms of risk. Though I do agree it needs to be done if they want a validated record. It's hardly rocket science. If it can do it once, it can do it twice.
GT119 said:
honda_exige said:
Super geeky but some clever guy over on Reddit has run a spectrograph analysis on the sound and highlighted even more inconsistencies, he later did an analysis on the sound of the Koenigsegg run and that matched perfectly to the claims, funny that. Given Robert Mitchell's recent Instagram Story post I'm guessing that's the subject of the next video.
Paste below:
[b]Below is a spectrogram / audio analysis of SSC's top speed run. Needless to say, this analysis also raises further questions about SSC's claims.
Throwaway for obvious reasons. Mods requested I post this here rather than create a new thread.
EDIT: Fixed an arithmetic mistake with gear ratios.
TLDR:
• Audio analysis from the video suggests the Tuatara shifted from 5 -> 6 at ~6900 RPM (not ~7700 as claimed). Additionally, RPM at VMAX appears to be ~7650 RPM (not ~8600 as claimed). This further confirms a mismatch between audio/video/telemetry.
• Low-frequency audio data may contain useful information about absolute vehicle speed. If the data is to be believed, top speed (based on the AUDIO) is approximately ~255 mph. This is not to suggest earlier video analysis is wrong. Rather, that the audio, video, and telemetry may ALL be different from one another - and that things are even weirder than previously believed. If this analysis is true, then either the final drive differs from what is claimed, or the gear ratios do.
Relevant Links:
• Onboard Video: Claimed SSC Top Speed World Record Run (Top Gear)
• Shmee150's Video re: SSC World Record
• Misha Charoudin's Video re: SSC World Record
• Motor Trend article including SSC statement
• Pastebin of Motor Trend article including SSC statement as of GMT 2:20, October 29, 2020
Background:
When an engine runs, the noise it produces has amplitude peaks at frequencies corresponding to the engine speed and its harmonics. Therefore it's possible to extract approximate engine speed data from an audio track of sufficient quality.
The conversion from units of audio frequency (Hz) to engine speed (RPM) is a factor 60. As the the Tuatara's redline is 8800 RPM, we expect the engine to produce primary frequencies below 150 Hz = 9000 RPM. However, analysis of the overtones (harmonics, integer multiples of the fundamental frequency) is sometimes easier than the fundamental frequency depending on the audio track involved. The first overtone is most relevant to this post - it has a conversion factor to RPM of 30 and thus we would not expect it to see the signal go beyond 300 Hz = 9000 RPM.
Before getting to the analysis, I would like to stress that this is speculative and simply a presentation of what the data appears to show. I am not making any accusations. Absent comprehensive telemetry data released by SSC, this video is one of the few things we have to work with and the goal of this post is to illustrate what that data appears to contain.
Engine Spectrogram:
1. A 0-300 Hz spectrogram of the audio (Hann window size of 32768), completely uncut from the video, looks like this. Many engine overtones are distinctly visible towards the start of the video. We will be looking at the first overtone as it is by far the most distinct. This first overtone begins at 50 Hz (1500 RPM idle) and is the distinct line visible across the entire spectrogram peaking at ~255 Hz. The fundamental tone is not loud enough to be "visible" for the first ~12 seconds, but appears around that point in time. At takeoff (~10s), the first overtone rumbles around, then rises to the first shift point at ~125 Hz, which is when we also see the first peak of the fundamental frequency (at ~62.5 Hz).
2. Due to excessive wind noise it's difficult to make out the fundamental during the top-speed run. Instead we look to the first overtone which tracks clearly the entire way.
3. At 1:00 is the final shift before the run begins. This happens at an overtone frequency of ~230 Hz or approx 6900 RPM. This disagrees with SSC's statement that the 5 -> 6 shift occurred at 7700 RPM. At 7700 RPM we would expect a frequency of around ~250 Hz, but the spectrogram does not seem to indicate any strong signal traces leading up to, or away from, a shift point at 250 Hz (though there are some splotches there). Yet, distinct traces are visible to either side of 250 Hz.
4. SSC has already stated the video and telemetry are from separate runs, this would seem to confirm this, as well as suggest that the audio is as well.
5. At 1:19 max engine speed is reached. This occurs at an overtone frequency of ~255 Hz or approx. 7650 RPM. This is within 5% of the engine speed (7300 RPM) estimated by Misha and Robert Mitchell in Misha's video linked above. This value differs substantially from SSC's claimed engine speed of 8600 RPM (from their recent statement), further suggesting the audio/video are not from the same run as the telemetry.
6. At no point during the entire video does engine speed fall within 1000 RPM of the claimed redline of 8800 RPM (to clarify, 8800 RPM is the redline, while 8600 RPM is the engine speed SSC claims to have reached at VMAX).
SPECULATION - Tire Spectrogram (Vehicle Velocity) - The following considers what is, at best, trace amounts of data. However I feel it is necessary to include for completeness.
1. Similarly to the engine, numerous other mechanical systems in the vehicle also give off fundamentals and overtones as they rotate. This includes road noise from wheels and tires. At particularly high speeds, any slight imperfections in these systems will appear at frequencies equal to their rotating speed (plus harmonics). Multiple things can cause this - for example, tiny imbalances in any of the wheels can manifest as road noise at speed.
2. Any audible signal from these components would be miniscule in comparison with engine noise. This, plus other factors (frequency near the lower cutoff of typical recording range, poor temporal resolution at low frequencies, etc) means the following spectrogram should be taken as speculation at best.
3. SSC cites a tire circumference of 89.125 inches, which is in line with the specified tire measurements and their higher-than-normal tire pressure. 330 mph is ~5800 inches per second, or an expected tire speed of ~65 rotations per second (~65 Hz signal, if any is visible).
4. We can look at the end of the video at the section after the driver has let off the throttle - when the engine noise is much lower and road noise is greater by comparison. The spectrogram here shows a dark trace dropping from ~50 Hz to ~25 Hz. It is not extremely sharp, but distinct enough to be sure something is there. Whether this trace indicates wheel speed is not clear.
5. If this trace is indeed caused by wheel speed, it is substantially far off from the 65 Hz frequency we'd expect to see if the vehicle were traveling 330 mph. (Note that the data are too noisy to say with certainty that there is not ALSO a trace coming from 65 Hz.)
6. By comparison, with a wheel of this size, wheel noise at a frequency of 50 Hz would equate to a vehicle speed of approximately ~255 mph, not 330 mph.
7. The Tuatara uses all seven gears - six during acceleration, plus a final upshift to 7th at the very end of the run. What are not clear are the actual gear ratios / final drive used in the car and whether they match the ratios in SSC's statement.
8. SSC's stated 5th gear top speed is 268 mph at 8800 RPM. In this gear, at 7650 RPM, the vehicle would travel only 234 mph. Using the claimed 6th gear ratio by comparison, it would travel 287 mph at this RPM. Both are a mismatch for the audio data suggesting 255 mph.
9. Please note that this calculated spectrogram speed also does not match the vehicle speed calculated in previous YouTube videos. This could suggest either the spectrogram analysis is incorrect (data too noisy, the trace is from another source, etc), that the audio and video are also mismatched, or something else is going on. In other words, it's within the realm of possibility that part or all of the analysis can't be trusted due to lack of more data. Or, it's possible I've made mistakes here. Finally, it's possible that the audio, video, and telemetry are all from separate runs, and that yes, the values claimed by SSC are disingenuous.
Steps to Replicate Analysis Yourself:
• Rip the audio from the YouTube world-record run video and import it to Audacity or an equivalent program (any program that offers spectrogram viewing)
• Change to "Spectrogram" mode (in Audacity, click the blue dropdown arrow to the left of the track)
• Adjust the Spectrogram Settings (in Audacity, again click the blue dropdown arrow -> "Spectrogram Settings"). Use Min Freq = 0 Hz, Max Freq = 300 Hz, and set a Hann Window Size of 32768[/b]
Nice bit of forensics there, but I fear Pommy bogan might blow an o-ring with all that data you presented.Paste below:
[b]Below is a spectrogram / audio analysis of SSC's top speed run. Needless to say, this analysis also raises further questions about SSC's claims.
Throwaway for obvious reasons. Mods requested I post this here rather than create a new thread.
EDIT: Fixed an arithmetic mistake with gear ratios.
TLDR:
• Audio analysis from the video suggests the Tuatara shifted from 5 -> 6 at ~6900 RPM (not ~7700 as claimed). Additionally, RPM at VMAX appears to be ~7650 RPM (not ~8600 as claimed). This further confirms a mismatch between audio/video/telemetry.
• Low-frequency audio data may contain useful information about absolute vehicle speed. If the data is to be believed, top speed (based on the AUDIO) is approximately ~255 mph. This is not to suggest earlier video analysis is wrong. Rather, that the audio, video, and telemetry may ALL be different from one another - and that things are even weirder than previously believed. If this analysis is true, then either the final drive differs from what is claimed, or the gear ratios do.
Relevant Links:
• Onboard Video: Claimed SSC Top Speed World Record Run (Top Gear)
• Shmee150's Video re: SSC World Record
• Misha Charoudin's Video re: SSC World Record
• Motor Trend article including SSC statement
• Pastebin of Motor Trend article including SSC statement as of GMT 2:20, October 29, 2020
Background:
When an engine runs, the noise it produces has amplitude peaks at frequencies corresponding to the engine speed and its harmonics. Therefore it's possible to extract approximate engine speed data from an audio track of sufficient quality.
The conversion from units of audio frequency (Hz) to engine speed (RPM) is a factor 60. As the the Tuatara's redline is 8800 RPM, we expect the engine to produce primary frequencies below 150 Hz = 9000 RPM. However, analysis of the overtones (harmonics, integer multiples of the fundamental frequency) is sometimes easier than the fundamental frequency depending on the audio track involved. The first overtone is most relevant to this post - it has a conversion factor to RPM of 30 and thus we would not expect it to see the signal go beyond 300 Hz = 9000 RPM.
Before getting to the analysis, I would like to stress that this is speculative and simply a presentation of what the data appears to show. I am not making any accusations. Absent comprehensive telemetry data released by SSC, this video is one of the few things we have to work with and the goal of this post is to illustrate what that data appears to contain.
Engine Spectrogram:
1. A 0-300 Hz spectrogram of the audio (Hann window size of 32768), completely uncut from the video, looks like this. Many engine overtones are distinctly visible towards the start of the video. We will be looking at the first overtone as it is by far the most distinct. This first overtone begins at 50 Hz (1500 RPM idle) and is the distinct line visible across the entire spectrogram peaking at ~255 Hz. The fundamental tone is not loud enough to be "visible" for the first ~12 seconds, but appears around that point in time. At takeoff (~10s), the first overtone rumbles around, then rises to the first shift point at ~125 Hz, which is when we also see the first peak of the fundamental frequency (at ~62.5 Hz).
2. Due to excessive wind noise it's difficult to make out the fundamental during the top-speed run. Instead we look to the first overtone which tracks clearly the entire way.
3. At 1:00 is the final shift before the run begins. This happens at an overtone frequency of ~230 Hz or approx 6900 RPM. This disagrees with SSC's statement that the 5 -> 6 shift occurred at 7700 RPM. At 7700 RPM we would expect a frequency of around ~250 Hz, but the spectrogram does not seem to indicate any strong signal traces leading up to, or away from, a shift point at 250 Hz (though there are some splotches there). Yet, distinct traces are visible to either side of 250 Hz.
4. SSC has already stated the video and telemetry are from separate runs, this would seem to confirm this, as well as suggest that the audio is as well.
5. At 1:19 max engine speed is reached. This occurs at an overtone frequency of ~255 Hz or approx. 7650 RPM. This is within 5% of the engine speed (7300 RPM) estimated by Misha and Robert Mitchell in Misha's video linked above. This value differs substantially from SSC's claimed engine speed of 8600 RPM (from their recent statement), further suggesting the audio/video are not from the same run as the telemetry.
6. At no point during the entire video does engine speed fall within 1000 RPM of the claimed redline of 8800 RPM (to clarify, 8800 RPM is the redline, while 8600 RPM is the engine speed SSC claims to have reached at VMAX).
SPECULATION - Tire Spectrogram (Vehicle Velocity) - The following considers what is, at best, trace amounts of data. However I feel it is necessary to include for completeness.
1. Similarly to the engine, numerous other mechanical systems in the vehicle also give off fundamentals and overtones as they rotate. This includes road noise from wheels and tires. At particularly high speeds, any slight imperfections in these systems will appear at frequencies equal to their rotating speed (plus harmonics). Multiple things can cause this - for example, tiny imbalances in any of the wheels can manifest as road noise at speed.
2. Any audible signal from these components would be miniscule in comparison with engine noise. This, plus other factors (frequency near the lower cutoff of typical recording range, poor temporal resolution at low frequencies, etc) means the following spectrogram should be taken as speculation at best.
3. SSC cites a tire circumference of 89.125 inches, which is in line with the specified tire measurements and their higher-than-normal tire pressure. 330 mph is ~5800 inches per second, or an expected tire speed of ~65 rotations per second (~65 Hz signal, if any is visible).
4. We can look at the end of the video at the section after the driver has let off the throttle - when the engine noise is much lower and road noise is greater by comparison. The spectrogram here shows a dark trace dropping from ~50 Hz to ~25 Hz. It is not extremely sharp, but distinct enough to be sure something is there. Whether this trace indicates wheel speed is not clear.
5. If this trace is indeed caused by wheel speed, it is substantially far off from the 65 Hz frequency we'd expect to see if the vehicle were traveling 330 mph. (Note that the data are too noisy to say with certainty that there is not ALSO a trace coming from 65 Hz.)
6. By comparison, with a wheel of this size, wheel noise at a frequency of 50 Hz would equate to a vehicle speed of approximately ~255 mph, not 330 mph.
7. The Tuatara uses all seven gears - six during acceleration, plus a final upshift to 7th at the very end of the run. What are not clear are the actual gear ratios / final drive used in the car and whether they match the ratios in SSC's statement.
8. SSC's stated 5th gear top speed is 268 mph at 8800 RPM. In this gear, at 7650 RPM, the vehicle would travel only 234 mph. Using the claimed 6th gear ratio by comparison, it would travel 287 mph at this RPM. Both are a mismatch for the audio data suggesting 255 mph.
9. Please note that this calculated spectrogram speed also does not match the vehicle speed calculated in previous YouTube videos. This could suggest either the spectrogram analysis is incorrect (data too noisy, the trace is from another source, etc), that the audio and video are also mismatched, or something else is going on. In other words, it's within the realm of possibility that part or all of the analysis can't be trusted due to lack of more data. Or, it's possible I've made mistakes here. Finally, it's possible that the audio, video, and telemetry are all from separate runs, and that yes, the values claimed by SSC are disingenuous.
Steps to Replicate Analysis Yourself:
• Rip the audio from the YouTube world-record run video and import it to Audacity or an equivalent program (any program that offers spectrogram viewing)
• Change to "Spectrogram" mode (in Audacity, click the blue dropdown arrow to the left of the track)
• Adjust the Spectrogram Settings (in Audacity, again click the blue dropdown arrow -> "Spectrogram Settings"). Use Min Freq = 0 Hz, Max Freq = 300 Hz, and set a Hann Window Size of 32768[/b]
Edited by honda_exige on Friday 30th October 15:44
Edited by Pommy on Saturday 31st October 07:29
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