Bahrain Winter Test #2: 27th Feb- 1st March

[Otispunkmeyer]

I don't get why people look at that with such incredulity. Compared to other things they manage to do in F1 design, working out power from exhaust note isn't that fancy!

[TonyToniTone]

RealSquirrels said:

here's a photo of someone doing a bit of sound recording

With a camera and speed gun?

[Some Gump]

Wow, that's wound a few of you up.

How is it hard not to see that any recording of engine noise can tell you the rpm quite easily? The comment about exhaust note etc - since moveable exhaust / inlet is banned, i'm not surehow the bore and length of the exhaust is relevent. If the exhaust note happens to be b flat it doesn't define the power - it's the rate of change that matters.

For hears now, commentary on the been / 5live etc relate to the teams deriving data from recordings. I have no reason to suspect that they're making that up, since after all it's a pretty basic task compared to CFD...

[sjn2004]

RealSquirrels said:

take some sound from an f1 car (e.g. in this case onboard footage)

filter it to leave just (mostly) the audio from the engine.

fast fourier transform (fft) it to get frequency vs time



identify which gear the car is in at each point (labelled on the graph)

from the rpm drops with each gear change, you can work out the relative ratios of the gear ratios

e.g. Example, passing from 6th to 7th gear the engine rpm drops from 19000 to 17050 meaning that the 6th gear ratio is 1.11 times the 7th gear ratio

correlate a time on your fft plot with the time the car passes through the speed trap. then you know speed and engine rpm so you can exactly calculate that gear ratio (because you know the diameter of the tyres).

you then have all of the other ratios from the information you have about the relative gear ratios.

so now you have a plot of engine speed and car speed vs time. knowing the mass of the car, and an estimate of drag, you can estimate engine power.

credit: all taken from this post http://www.f1technical.net/forum/viewtopic.php?t=2...

here is another article about it http://www.grandprix.com/ft/ft00345.html

Edited by RealSquirrels on Thursday 6th March 23:08

One of my points exactly, quote from your link

"All that is needed to sense the sound is a good quality microphone. If the microphone is stationary with respect to a moving car, the motion of the car - the well-known Doppler effect - will affect the frequency picked up. When a vehicle, such as a train or a car, passes someone standing by the tracks or road, the sound of the approaching vehicle is higher pitched than when it is moving away from the listener. There is an abrupt change in frequency of the sound as the vehicle passes, and it is only at the moment when it is opposite the listener that the true frequency is heard.

Thus it would be no use to sense the sound of an engine using trackside microphones; the microphone must be placed on the car itself."

[sjn2004]

zac510 said:

ash73 said:

All that maths and then *guess* the fuel load and drag...?

You have ballpark drag from your own car's numbers and fuel load from the stint of laps.
You're arguing this is wrong for not being 100% perfect? I imagine even imperfect information is very valuable and over time as you build larger datasets you can narrow it down or at least see it relative to other teams.

I can see this being a aeroplane on a conveyor belt type thread soon.

If average BHP is 750 that 50bhp difference being quoted equates to approx a 6.6% increase in power.

Take drag and weight as two variables. If your estimates of those were to a level of accuracy of 97% for each, the margin of error there alone would be 6% , nearly equating to 50bhp! So the competitors car could have the same bhp as yours but your data might suggest that they have either 50 bhp more or 50 bhp less depending on how you guessed weight and aero.. Totally useless.

Rather than make lots of guesses which you hope to derive some accurate figure from, why not just guess the bhp to start with!

[sjn2004]

Some Gump said:

Wow, that's wound a few of you up.

How is it hard not to see that any recording of engine noise can tell you the rpm quite easily? The comment about exhaust note etc - since moveable exhaust / inlet is banned, i'm not surehow the bore and length of the exhaust is relevent. If the exhaust note happens to be b flat it doesn't define the power - it's the rate of change that matters.

For hears now, commentary on the been / 5live etc relate to the teams deriving data from recordings. I have no reason to suspect that they're making that up, since after all it's a pretty basic task compared to CFD...

Doppler effect.
Nobodys wound up, just a fun conversation.

You're making it too complicated. All that is needed is to monitor a section of track where the cars are under full acceleration. You have you own car as a reference point/ data set and overlaying the tracking data of the competitors cars will give a reasonable idea of bhp relative to your own car.

The drivers of course will all know who is up/down on power.

[Daniel1]

Just a little bit of trivia - I know that the Mercedes engine factory listen to the live tv feeds for clues about engine health.

[S0 What]

Otispunkmeyer said:

I don't get why people look at that with such incredulity. Compared to other things they manage to do in F1 design, working out power from exhaust note isn't that fancy!

I know, Martin Brundle mentioned it years ago, when he was with James Allen on ITV, it's not new and not a secret

[zac510]

I suppose all of the teams could be wrong.

[Bradgate]

ash73 said:

I bet the best source of info = lonely engineer + hotel bar + pretty girl + fluttering eyelashes

The challenge there would be finding a suitably attractive and willing young lady who could understand what the engineer was talking about :

“Well, Crystalle, the integration between the MGU-H and the MGU-K with the standardised ECU produces significant variability in the torque delivery characteristics….” Etc etc

“Ooh, Gary you’re so clever! What colour did you say the car was?”

[toppstuff]

Bradgate said:

ash73 said:

I bet the best source of info = lonely engineer + hotel bar + pretty girl + fluttering eyelashes

The challenge there would be finding a suitably attractive and willing young lady who could understand what the engineer was talking about :

“Well, Crystalle, the integration between the MGU-H and the MGU-K with the standardised ECU produces significant variability in the torque delivery characteristics….” Etc etc

“Ooh, Gary you’re so clever! What colour did you say the car was?”

That is easily solved. I am sure that F1 teams are good enough at telemetry to incorporate a GPS and a high power digital audio feed, all hidden inside the seams of her lace underwear.