Markus Stiepel <[email hidden]> wrote in message
news:82vc2i$hb0$[email hidden]...
> Hi!
> I don't really know if it's only me who has experienced or noticed this:
> When I run a race at Talladega and I am leading a train of cars mylaptimes
> are much quicker than the times when I run my laps on my own. I'm not
> talking about getting bump-drafted, I tested this several times: I lead a
> pack (without getting passed or bumped) for several laps and I did 47.888,
> then I let myself drop back (in the same race!) out of range of the train,
> consequently I could do laps no faster than 48.088, no matter how manylaps
Well this is pretty much what is supposed to happen. It would seem the
physics is not that badin N3 if you can see this effect.
> I did. It's logical that a train runs faster than a solo-car, but onlywhen
> there are constant lead-changes in that train (like we can see in
Constant lead changes slow the "train" and cause the second pack to
catch up. You don't watch many Nascar races on ESPN I guess :-)
They are faster when they stay in a line.
--
Header address intentionally scrambled to ward off the spamming hordes.
cisko [AT] ix [DOT] netcom [DOT] com
> bicycle-races), commonly known as "working together". IMHO the train
should
> *not* be faster when the leader is the same lap after lap. Is this a bug
or
> are there certain aerodynamic effects from the Pos.2-car on the leader
(e.g.
> the "winds" of the leader usually "break" behind him, but if he is
followed
> by a car real close, then these winds break behind the 2nd car causing the
> leader to benefit from this)?
> Excuse my limited vocabulary please, but I hope I made myself
> understandable.
> Thanx for listening
> Markus
>
>
hmmmmmm, I thought this would be the reason for a train going faster than a
lone car, but I figured the following: The second car (B) has no air to
break, correct, and in effect will be much faster than the leader (A)
despite the vacuum behind him, thus he has to back off from the throttle at
some point which in turn won't achieve faster times unless he overtakes A
*without* backing off, which in turn desires A go *one* lane higher than he
usually would and immediately slotting in behind B (not jockeying, working
together). BUT, as I described initially, if A always stays up front and B
always real close behind, aren't these two cars to be considered as *one*
long vehicle.............duhh.......where's my thinking-error?
Markus
Dave Henrie <[email hidden]> schrieb in im Newsbeitrag:
[email hidden]...
Quoted text (19 lines)
> The reason bike riders keep swapping the lead is because the front > rider > has more work to do...which means increased fatigue. So the bike riders > constantly > swap ends to even the work load. > In a Winston Cup drive, a line of two or more should always be faster, > not only because the lead car is breaking the wind and creating an air > bubble > for the followers. But the cars in line also help by "pushing" what air > is > left back to the front car which makes his lap times improve. constant > lead changes > disrupt the air flow and slow everyone down. A tactic at every drafting > track > is for a few drivers to try and "leave" the pack by running in single > file while > the the group behind slows down by constantly jockeying for posisiton. > dave henrie >Hi!
I don't really know if it's only me who has experienced or noticed this:
When I run a race at Talladega and I am leading a train of cars my laptimes
are much quicker than the times when I run my laps on my own. I'm not
talking about getting bump-drafted, I tested this several times: I lead a
pack (without getting passed or bumped) for several laps and I did 47.888,
then I let myself drop back (in the same race!) out of range of the train,
consequently I could do laps no faster than 48.088, no matter how many laps
I did. It's logical that a train runs faster than a solo-car, but only when
there are constant lead-changes in that train (like we can see in
bicycle-races), commonly known as "working together". IMHO the train should
*not* be faster when the leader is the same lap after lap. Is this a bug or
are there certain aerodynamic effects from the Pos.2-car on the leader (e.g.
the "winds" of the leader usually "break" behind him, but if he is followed
by a car real close, then these winds break behind the 2nd car causing the
leader to benefit from this)?
Excuse my limited vocabulary please, but I hope I made myself
understandable.
Thanx for listening
Markus
The reason bike riders keep swapping the lead is because the front
rider
has more work to do...which means increased fatigue. So the bike riders
constantly
swap ends to even the work load.
In a Winston Cup drive, a line of two or more should always be faster,
not only because the lead car is breaking the wind and creating an air
bubble
for the followers. But the cars in line also help by "pushing" what air
is
left back to the front car which makes his lap times improve. constant
lead changes
disrupt the air flow and slow everyone down. A tactic at every drafting
track
is for a few drivers to try and "leave" the pack by running in single
file while
the the group behind slows down by constantly jockeying for posisiton.
dave henrie
Markus Stiepel wrote:
Quoted text (21 lines)
> > Hi! > I don't really know if it's only me who has experienced or noticed this: > When I run a race at Talladega and I am leading a train of cars my laptimes > are much quicker than the times when I run my laps on my own. I'm not > talking about getting bump-drafted, I tested this several times: I lead a > pack (without getting passed or bumped) for several laps and I did 47.888, > then I let myself drop back (in the same race!) out of range of the train, > consequently I could do laps no faster than 48.088, no matter how many laps > I did. It's logical that a train runs faster than a solo-car, but only when > there are constant lead-changes in that train (like we can see in > bicycle-races), commonly known as "working together". IMHO the train should > *not* be faster when the leader is the same lap after lap. Is this a bug or > are there certain aerodynamic effects from the Pos.2-car on the leader (e.g. > the "winds" of the leader usually "break" behind him, but if he is followed > by a car real close, then these winds break behind the 2nd car causing the > leader to benefit from this)? > Excuse my limited vocabulary please, but I hope I made myself > understandable. > Thanx for listening > MarkusYeah, it's called drafting. The front car breaks open the air, allowing less resistance
for any and all cars that follow. Also, if you have a car close behind you, that car
will help take the air off your rear spoiler, making your car faster from less wind
resistance. N3 models this pretty well.
--
Kenny L.
#14 Generic Chevy
PRC Member
Wall Scrapers Racing Team
"Markus Stiepel" <[email hidden]> wrote in message
news:82vc2i$hb0$[email hidden]...
> Hi!
> I don't really know if it's only me who has experienced or noticed this:
> When I run a race at Talladega and I am leading a train of cars my laptimes
> are much quicker than the times when I run my laps on my own. I'm not
> talking about getting bump-drafted, I tested this several times: I lead a
> pack (without getting passed or bumped) for several laps and I did 47.888,
> then I let myself drop back (in the same race!) out of range of the train,
> consequently I could do laps no faster than 48.088, no matter how many laps
> I did. It's logical that a train runs faster than a solo-car, but only when
> there are constant lead-changes in that train (like we can see in
> bicycle-races), commonly known as "working together". IMHO the train should
> *not* be faster when the leader is the same lap after lap. Is this a bug or
> are there certain aerodynamic effects from the Pos.2-car on the leader (e.g.
> the "winds" of the leader usually "break" behind him, but if he is followed
> by a car real close, then these winds break behind the 2nd car causing the
> leader to benefit from this)?
> Excuse my limited vocabulary please, but I hope I made myself
> understandable.
> Thanx for listening
> Markus
>
>
What happens whe you are out of the draft, is the air rushes over the top
and under the car, the air over the top of the car hits the back spoiler and
travels down, which creates downforce and drag. Also, the car cuts a hole
through the air, leaving a big amount of vacuum and turbulence in the open
area behind the car under the spoiler. This vacuum must be filled, so what
happens is that vacuum is trying to be filled by the car, thus holding it
back and slowing it down. In a train of cars, when there is a car behind
you, even if it is one or two car lengths behind, you, it fills the void
behind your car that would normally have that vacuum or turbulent air, thus
if there is no vacuum, there is no holding back the car. maybe you've heard
the expression "taking the air off his spoiler"? This is literally what
happens, when a car gets too close to the car in front, without touching
him. The air coming off the spoiler can't go down behind the car creating
downforce, it is pushed up instead by the car behind it(the air goes over
the roof of the trailing car.) It makes a car really loose, but the plus
side is there is no vacuum behind the car holding it back, which gives you
more top speed.
Markus Stiepel <[email hidden]> wrote in message
news:82vc2i$hb0$[email hidden]...
> Hi!
> I don't really know if it's only me who has experienced or noticed this:
> When I run a race at Talladega and I am leading a train of cars mylaptimes
> are much quicker than the times when I run my laps on my own. I'm not
> talking about getting bump-drafted, I tested this several times: I lead a
> pack (without getting passed or bumped) for several laps and I did 47.888,
> then I let myself drop back (in the same race!) out of range of the train,
> consequently I could do laps no faster than 48.088, no matter how manylaps
> I did. It's logical that a train runs faster than a solo-car, but onlywhen
> there are constant lead-changes in that train (like we can see in
> bicycle-races), commonly known as "working together". IMHO the trainshould
> *not* be faster when the leader is the same lap after lap. Is this a bugor
> are there certain aerodynamic effects from the Pos.2-car on the leader(e.g.
> the "winds" of the leader usually "break" behind him, but if he isfollowed
Quoted text (8 lines)
> by a car real close, then these winds break behind the 2nd car causing the > leader to benefit from this)? > Excuse my limited vocabulary please, but I hope I made myself > understandable. > Thanx for listening > Markus > >Let's put it like this.
Car A is the leader, B behind him, followed by C.
All the cars have 750 horsepower. Let's say that when you are running alone
at 185 mph, 25 horsepower (arbitrary value) is used to overcome the drag at
the front of the the car and 10 horsepower is used to overcome the drag at
the back of the car.
If car B pulls in close enough to Car A that he takes some of the drag away
from the rear of Car A, he has effectively increased the horsepower
available for propelling Car A around the track.
Another way to look at it:
Each Car is using 35 horsepower to move the air out of the way. When they
form a train, they remove some of the drag from the total system. For
instance, alone, Cars A and B use 35 horsepower each, but if Car B pulls
10'' from Car A's bumper, then Car A might have 25 units of drag, and Car B
might have 18. The whole is less than the sum of the parts.
This makes no sense, does it?
--
Aaron Gillum
RDOS Director of Operations
http://www.racing-design.com/rdos Now Accepting Applications!
[email hidden]
--
"You could have been paid to read this message. www.getpaid4.com/?bargler "
--
You are correct in assuming that Car B has much less total drag than Car A,
but a smart driver in Car B knows that it is best to ease up a bit and let
Car A drag you around the track.
Markus Stiepel <[email hidden]> wrote in message
news:82vh8j$jpp$[email hidden]...
> hmmmmmm, I thought this would be the reason for a train going faster than
a
> lone car, but I figured the following: The second car (B) has no air to
> break, correct, and in effect will be much faster than the leader (A)
> despite the vacuum behind him, thus he has to back off from the throttle
at
> some point which in turn won't achieve faster times unless he overtakes A
> *without* backing off, which in turn desires A go *one* lane higher than
he
> usually would and immediately slotting in behind B (not jockeying, working
> together). BUT, as I described initially, if A always stays up front and B
> always real close behind, aren't these two cars to be considered as *one*
> long vehicle.............duhh.......where's my thinking-error?
> Markus
>
>
>
> Dave Henrie <[email hidden]> schrieb in im Newsbeitrag:
> [email hidden]...
> > The reason bike riders keep swapping the lead is because the front
> > rider
> > has more work to do...which means increased fatigue. So the bike riders
> > constantly
> > swap ends to even the work load.
> > In a Winston Cup drive, a line of two or more should always be faster,
> > not only because the lead car is breaking the wind and creating an air
> > bubble
> > for the followers. But the cars in line also help by "pushing" what air
> > is
> > left back to the front car which makes his lap times improve. constant
> > lead changes
> > disrupt the air flow and slow everyone down. A tactic at every drafting
> > track
> > is for a few drivers to try and "leave" the pack by running in single
> > file while
> > the the group behind slows down by constantly jockeying for posisiton.
> > dave henrie
> >
>
>
>
Just to summarize what others have already mentioned here,
both the front and rear car experience a drag reduction
when close together. The rear car sees a greater benefit
than the the front. Because the front car's drag
IS reduced slightly, the top speed of the pair is increased.
Both cars see some degradations also. The rear spoiler downforce
of the leading car is reduced (changing it's handling) and
the following car is receiving less cooling air and its
downforce can be lower also. With some vehicle types,
the following car may have additional aero
performance reductions through increased turbulence
on forward aero surfaces or underbody.
A good and accessible reference for a discussion of this
is Van Valkenburgh's book (which also includes some references
to the early technical literature.)
"Race Car Engineering and Mechanics," Paul Van Valkenburgh,
Published by author: Box 3611 Seal Beach, CA 90740, 1992.
(or HP Books, NY, NY. ) ISBN 0-9617425-0-X
--
Matthew V. Jessick Motorsims
Vehicle Dynamics Engineer (972)910-8866 Ext.125, Fax: (972)910-8216
Quoted text (11 lines)
> hmmmmmm, I thought this would be the reason for a train going faster than a > lone car, but I figured the following: The second car (B) has no air to > break, correct, and in effect will be much faster than the leader (A) > despite the vacuum behind him, thus he has to back off from the throttle at > some point which in turn won't achieve faster times unless he overtakes A > *without* backing off, which in turn desires A go *one* lane higher than he > usually would and immediately slotting in behind B (not jockeying, working > together). BUT, as I described initially, if A always stays up front and B > always real close behind, aren't these two cars to be considered as *one* > long vehicle.............duhh.......where's my thinking-error? > Markus> Well this is pretty much what is supposed to happen. It would seem the
> physics is not that badin N3 if you can see this effect.
N3 also allows you to get a small benefit from the draft when close
alongside of a car as well. This is also accurate as DE is very good
at getting that help in real life. It will slow you both down when
compared to a train of cars but does benefit the car on the low side
for several hundred yards or so. Great for that dash to the S/F line.
If you do this with a human driver you better both be good!
--
Rich Koehler
rgkoehler(at)lucent(dot)com
killerk(at)home(dot)com
