Slipstream distance is still too far

[HornetMaX]

for me, it depends on the distance: the faster the one in front of you goes, bigger is the quantity of air it moves ( sorry for my italian-english lol ). Just my opinion

Hmm ... doesn't work exactly like that.

AFAIK, slipstream is a zone of low pressure practically sucking the following vehicle in. The "quantity of moved air" is not really relevant. Speed is, as the size of the zone depends on it.

MaX.

[BOBR6 84]

Its a tough one..

Look at moto3 it seems very important to slipstream the rider infront but it sometimes looks like it takes the whole length of the straight to have an effect.. U usually see the rider behind take a wider entry onto the straight to get a better run for the line if its the last lap..

Faster bikes.. NW200 for eg. Top speeds are increased alot with slipstream!

So I would say it has a bigger effect at higher speed..

[BOBR6 84]

Did anybody watch that tv programme.. ''Speed with Guy martin'' the episode where he gets in the trucks slipstream on a pushbike and does about 100mph?

Truck had a huge windbreaker but the air pocket was still very small..

[Arvoss]

I looked at a lot of onboard videos to find another example but it's difficult to find a clean slipstream. (corner exit, topspeed of the bike,...)

It starts at 2:54
Speed increase at 2:59

https://www.youtube.com/v/Nzvlu8603J8

[HornetMaX]

Arvoss, you won't be able to grab any info from videos: maybe the bike behind was just faster, we don't know at which speed they were etc.

I guess the best shot is to ask our real riders.

MaX.

[Desteban]

I can try to watch the data recording next time when I get some slipstream, then I can says something definite.
If I say anything now it wouldn't be more than a guess...

[HornetMaX]

I can try to watch the data recording next time when I get some slipstream, then I can says something definite.
If I say anything now it wouldn't be more than a guess...

I really doubt we can gather something useful from the data recording, but if you can have a look why not.

I've contacted a more knowledgeable (wrt me) friend of mine, I should come up with some sort of information soon.

MaX.

[pumuky]

+1

[C21]

sometimes looks like it takes the whole length of the straight to have an effect.

Not only sometimes.
I needed the whole star/finish straight to get next to my team mate riding Brno in 2004 to outbrake him. Both bikes had the same gearing and engine are mostly equal. My engine was 2hp up on his one (same dyno, same day).
I posted a few days ago that i would say an increase will be noticable at 3 bike length. If i remember correctly i would take it down to 2 bike length now.....but the speed increase is not that much....the longer the straight the more it will be.....i would say a speed increase between 5-10km/h maximum. Funny when the wind is facing you from the front...you sneak behind the one in front of you then try to overtake him but stuck on the same height of his fairung nose due to the wind......

[HornetMaX]

sometimes looks like it takes the whole length of the straight to have an effect.

Not only sometimes.
I needed the whole star/finish straight to get next to my team mate riding Brno in 2004 to outbrake him.

At which speed ?

MaX.

[C21]

Max i told you we don´t have speedos at the track bikes 
I can only presume the speed upon the gearing but i have to look into my sheets and run a calculation.
gearing was 15/50 or 15/49 if i remember correctly.
Speed must be 220-230 KM/h i presume.
Running 3rd gear on the beginning of the straight up to 6th gear...

[HornetMaX]

Max i told you we don´t have speedos at the track bikes 

Oh, forgot it was you, sorry 

All the info I'm finding on  the subject is very messed up ... annoying.

MaX.

[BOBR6 84]

try and find a video of "speed, with guy martin" was some good slipstream info on that..

[HornetMaX]

Wow, it's really really a PITA that slipstream stuff ...

First part of this article (http://www.recumbents.com/wisil/demma/aero_review.htm), from beginning up to 1st paragraph after the 1st graph.

Results are different for streamlined / poorly streamlined vehicles and I'm not sure where racing motorbikes falls (somewhere in between, probably closer to poorly streamlined case).

Speed is not mentioned, but I'll ask C21 once again

For streamlined vehicles you can see some funky stuff: when the following vehicle approaches he gets a benefit but once he gets too close he's worse off.
Also, the front vehicle gets a benefit too once the following vehicle is close enough. This is a bit surprising but makes sense. It is also a know fact in Nascar racing, where two cars running close can go faster than a single one (two-car drafting, or tandem drafting, banned by Nascar in ... 2014 !!!

For poorly streamlined vehicles it seems to be even worse: for the trailer, Cd goes down, then up and then down again.

I'm more and more convinced we don't need this level of detail.

MaX.

[C21]

I'm more and more convinced we don't need this level of detail.

Correct but the slipstream effect has to be reduced!

Speed is not mentioned, but I'll ask C21 once again

NOOOOOOOOOOOOOOOOOOOO