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#31 Pavel

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Posted Dec 22 2010 - 06:45 AM

Here is scans that were on RSC. Maybe someone didn't see it.

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#32 richard cooke

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Posted Dec 22 2010 - 08:05 AM

View Postbrr, on Dec 20 2010 - 02:52 PM, said:

View PostTvO, on Dec 20 2010 - 02:30 PM, said:

Apperantly, teams running a car in the Indy 500 have to take into account that the car can experience a decrease in drag when it's as much as 9 seconds behind the leading car.

What is the source of this information?
In that year's TV coverage one of the race teams told the reporter that their telemetry detected a decrease in drag 9 seconds behind the car in front.

Richard

#33 Rudy Dingemans

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Posted Dec 22 2010 - 02:10 PM

View PostTvO, on Dec 20 2010 - 04:31 PM, said:

Why should it be weakened? Where does all this sceptisism come from?

Experience in GPL with the later patches (which were partly botched imho) Tommie. Like I said the overall slipstream effect is better than it used to be, but it's definitely too strong at large distances. You start really getting sucked forward with the other car barely in sight yet, instead of getting sucked forward when getting actually near to the car in front.  :2c:

I've had 65 and 66 races where guys behind me lost it and spun off (or got off the track) at Monza and then were right back on my tail two laps later.  :hmm:   That's just not realistic, and that's final - no matter what anyone says here.  

View PostBob Simpson, on Dec 21 2010 - 10:49 AM, said:

The trouble with this GPL simulation is the limitation that it only covers one condition.  There are no side wind factors, nor do the slightly different aerodynamic qualities of the cars within each mod factor in.

Bob's probably on to something here. One of the reasons that the draft is too strong at distance (especially for the smaller/slower 65 and 66 cars) is probably that IRL, it gets "spoiled" after a few seconds by side winds and other aerodynamic factors.

(I still don't buy Bob's reasoning of slipstreaming on bicycles, I don't think that exists (it just reduces the head wind if you tuck in behind the cyclist in front, but front drag reduction is not the same as a slipstream - which "sucks you forward" and bicycles just don't go fast enough to punch such a hole in the air needed to do that). But apart from that, I think he has part of the explanation here.)

Regards, Rudy
(GPLRank: -40)

Edited by Rudy Dingemans, Dec 22 2010 - 02:11 PM.


#34 M Needforspeed

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Posted Dec 22 2010 - 02:19 PM

View PostRudy Dingemans, on Dec 22 2010 - 02:10 PM, said:

View PostTvO, on Dec 20 2010 - 04:31 PM, said:

Why should it be weakened? Where does all this sceptisism come from?

Experience in GPL with the later patches (which were partly botched imho) Tommie. Like I said the overall slipstream effect is better than it used to be, but it's definitely too strong at large distances. You start really getting sucked forward with the other car barely in sight yet, instead of getting sucked forward when getting actually near to the car in front.  :2c:

I've had 65 and 66 races where guys behind me lost it and spun off (or got off the track) at Monza and then were right back on my tail two laps later.  :hmm:   That's just not realistic, and that's final - no matter what anyone says here.  



Regards, Rudy
(GPLRank: -40)


   Can you give a number in meters, Rudy ? How much car sizes back did you experienced what seems a power like a storm huge slipstream ??

Only thing I can say is I just finished "the Jack brabham story " book, and he gives figures of tow still faraway from the car ahead.

Edited by M Needforspeed, Dec 22 2010 - 02:24 PM.


#35 Lee200

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Posted Dec 22 2010 - 02:34 PM

View PostPavel, on Dec 22 2010 - 06:45 AM, said:

Here is scans that were on RSC. Maybe someone didn't see it.

Thanks Pavel or these.  I'd not seen them before.

Do you have the next month's installment which supposedly covered the theory behind slipstreaming?

#36 richard cooke

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Posted Dec 22 2010 - 02:50 PM

View PostM Needforspeed, on Dec 22 2010 - 02:19 PM, said:

Only thing I can say is I just finished "the Jack brabham story " book, and he gives figures of tow still faraway from the car ahead.
I remember reading an article where Jack Brabham claimed he got a tow 400yards away, but have never been able to find the article again.  What does the book say?

Richard

#37 John Woods

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Posted Dec 22 2010 - 03:30 PM

Just completed several laps at Indy with average front and back straight times of about 13 seconds, which would mean an effect at 9 seconds would be, for instance, between the exit of turn 2 or 4 to a point about 3/4 of the way down the straight, (as if my experience makes any difference).

Thanks for the article, Pavel.

Anyone know, does the drafting effect apply to wheels independently, or just the tub, or all?

#38 M Needforspeed

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Posted Dec 22 2010 - 03:36 PM

View Postrichard cooke, on Dec 22 2010 - 02:50 PM, said:

View PostM Needforspeed, on Dec 22 2010 - 02:19 PM, said:

Only thing I can say is I just finished "the Jack brabham story " book, and he gives figures of tow still faraway from the car ahead.
I remember reading an article where Jack Brabham claimed he got a tow 400yards away, but have never been able to find the article again.  What does the book say?

Richard
Richard,


that' s precisely in that book ! I will check and post the excerpt

#39 M Needforspeed

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Posted Dec 22 2010 - 03:38 PM

View Postrichard cooke, on Dec 22 2010 - 02:50 PM, said:

View PostM Needforspeed, on Dec 22 2010 - 02:19 PM, said:

Only thing I can say is I just finished "the Jack brabham story " book, and he gives figures of tow still faraway from the car ahead.
I remember reading an article where Jack Brabham claimed he got a tow 400yards away, but have never been able to find the article again.  What does the book say?

Richard
Richard,


that' s precisely in that book, released in 2004, he wrote himself with a little help from Doug Nye! I will check and post the excerpt

Edited by M Needforspeed, Dec 22 2010 - 04:29 PM.


#40 M Needforspeed

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Posted Dec 22 2010 - 04:13 PM

Got it ! P 213

Brabham describe the Reims Formula 2 1964 race with the BT10 Ford SCA 1000 cc engine  " the fastest part of the Reims circuit was the long downhill straight - actually the main Reims - Soissons road into Thillois corner, down which our little 1 litre cars were hitting 142 mph ( 229 Km/h).Slipstreming effect could be felt at considerable range.To break another car out of your "tow" you had to pull at least 400 yards ( 366 m) ahead of it "

Towards the end of the race Alan Rees, in Roy Winkelmann's private Brabham, and I had managed to break some 500 yards ( 457 m) clear of the pursuing pack and he led into Thillois, the final right-hander entering the long, undulating finish straight.I was hoping to slipstream him out of that corner and slingshot ahead at the line, but he was playing the same game.We both crept unbelievably slowly round Thillois, and when he booted it for the line I couldn 't quite get by and he won by half a length  


what's remarkable is that if you go 400 m back at Reims, there is a good chance your car is still going downhill, and the car towing in front is in a lower position and thus isn't on the same altitude airflow ...How the effect can be so strong or simply felt?    
  
So there seems we can set GPL slipstreaming on a wide range of numbers !

Don't be too conservative Rudy,listen to the "wise quiet silent man" of motor Racing, as Black Jack was also descibed.

Edited by M Needforspeed, Dec 22 2010 - 05:17 PM.


#41 Pavel

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Posted Dec 22 2010 - 04:31 PM

View PostLee200, on Dec 22 2010 - 02:34 PM, said:

Thanks Pavel or these.  I'd not seen them before.

Do you have the next month's installment which supposedly covered the theory behind slipstreaming?
This are not my scans. Someone posted it on RSC in same topic about drafting. So I don't have article from the next month.

Every time when we talk about slipstreaming there are references to 1966 Reims GP. If I'm right, weather at Reims always was very hot (and in 1966 too). Reims track run through the fields and there are no many trees around. So under the sun air upon asphalt warm up even more. Warm air have lower density. So 'tunel' in the air after car don't close as quick, as in cold weather, I think. And this don't work on most of others track. For example half of the Monza is under the trees.

#42 M Needforspeed

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Posted Dec 22 2010 - 04:36 PM

Sorry, post edited.That's not the 1966 race Brabham talk about, but the 1964 F2 race, with the modest Ford SCA engines.

Edited by M Needforspeed, Dec 22 2010 - 04:43 PM.


#43 Bob Simpson

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Posted Dec 22 2010 - 04:41 PM

View PostRudy Dingemans, on Dec 22 2010 - 02:10 PM, said:

(I still don't buy Bob's reasoning of slipstreaming on bicycles, I don't think that exists (it just reduces the head wind if you tuck in behind the cyclist in front, but front drag reduction is not the same as a slipstream - which "sucks you forward" and bicycles just don't go fast enough to punch such a hole in the air needed to do that). But apart from that, I think he has part of the explanation here.)
Here, we're getting into problems with definition between "slipstream", "draft" and "drag reduction".   To me they are all the same, but I could be wrong.

There have been some high speed records in bicycling where the rider tucked in behind a special wind block (both terms "slipstream" and "drafting" are used in that articled BTW).  The car and bike got up to 150 mph but I read in other reports that if the rider had gone back another half meter, he would have been battered by the wind and lost all advantage.  There was, in fact a pushing effect on the rider due to the design of the wind shield.

The air behind a regular car is much more complicated.  There is turbulence with the air going forward or not at varying speeds depending on where you are in all three axes.

Edited by Bob Simpson, Dec 22 2010 - 04:58 PM.


#44 Pavel

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Posted Dec 22 2010 - 04:44 PM

Thanks M Needforspeed,
Intresting: with f2 car at 142 mph - 400 yards, and with f1 car at 190 mph - ?

#45 Phil

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Posted Dec 22 2010 - 05:02 PM

View PostM Needforspeed, on Dec 22 2010 - 04:13 PM, said:

To break another car out of your "tow" you had to pull at least 400 yards ( 435 m) ahead of it
400 yards is 366 metres.




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