Quote from Ardent :

the answer to your question is already given in the text you quoted. On a bicycle the draft is not used to gain speed (as tristancliffe explained) but for reducing the energy needed to maintain a given speed.
If you ever drove with a bicycle (and i'm sure you did) then you will have felt air resistance which you have to work against. Someone who is following you closely will have less air resistance hence he needs less energy to go your speed and will probably be less tired after arrival.

Professional bicycle teams who drive tour de france usually consist of one top driver and 5 or 6 "helpers", who are just there to lower the air resistance for their top driver letting him draft as long as they can. They are basically sacrificed in the process because they have used up all their energy long before the race ends.

Yes but you are missing the point, If they can draft, so can karts. But for karts, it's not to lower the energy required to stay at that speed, it's to raise the speed and use the same amount of energy.

Quote from tristancliffe :

Sure.

Bumpdrafting (as in LFS, and as under discussion here [originally]) is when the following car is 'sucked' along by the lead car until the following cars speed (car 2) is greater than that of the lead car (car 1). So V1 < V2 (where V is velocity).

Now, car 2 uses his additional kinetic energy (0.5mv^2) to collide inelastically (but elastically in LFS I think) with car 1. This imparts an impulse upon car 1, which creates a positive change in car 1's momentum. This in turn increases car 1's kinetic energy and, therefore, speed.

Now V1 > V2, and V1ii > V1i.

Therefore Car 1 is travelling slightly faster than car 2, and a small gap opens up between the two. This gap creates a low pressure region (gauge pressure) between 1 and 2, which causes a slipstream/draft effect. The speed (and hence kinetic energy & momentum) of car 2 is increased due to this, causing the gap to decrease. When the gap equals zero, the same transfer of speed, momentum and energy (all the same thing really) is transferred from 2 to 1, causing an increase in speed, creating a gap, creating a draft. V1n > V1i and V2n > V2i. Ad infinitum (or until car 1 brakes because car 2 is driven by a conceited eejit).



Bumpdrafting is all about the draft. If the draft is not strong, then it cannot occur. The draft is not strong enough in karts, and as such it CANNOT occur. Anyone who mistakenly thinks that bumpdrafting exists in karts or R/C cars (or even BTCC) is mistaken and deluded. Car 2 in that instance could have more power, less drag, higher Tn-1 exit speed or some other advantage that causes him to bump car 1. It may be at a point on the circuit where passing is not possible, but car 2 wants to retain as much speed as possible - he can do this by sacrificing some of his speed to car 1 and thus they both travel quicker. It is not, until speeds reach much over 130mph in my estimation, that bumpdrafting (i.e. with a draft or slipstream) could actually provide any worthwhile speed benefit.

Having said that, I will still brake if someone tries it with me. And don't say I'm mean or wrong for doing that - cos now I've warned you all, and you can't blame me when you forget I said it

Okay, one thing still is bugging me from that explaination. If karts can't produce that strong of a draft to allow for bump drafting from any distance, then how is drafting a bicycle and another human possible?

http://www.aerospaceweb.org/qu ... /aerodynamics/q0092.shtml

Quote :

Drafting in bicycling, running, and inline skating However, drafting isn't limited to the world of motor sports alone. Runners, bicyclers, and inline skaters also employ the technique, but in a slightly different way. While racecar drivers use drafting to increase their speed, their non-motor sports counterparts emphasize reducing energy consumption. A runner utilizes drafting by following closely behind an opponent. The opponent breaks the headwind and creates a slipstream in his wake where the second runner can get by exerting less energy while still maintaining the same speed. In a marathon race, this technique may save 5 to 10 seconds per mile.

If a human body can give off a slipstream to allow for drafting, why can't the exposed human body in a kart give off that same effect?

I believe its ctrl+tab, don't hold me to that though.

Quote from Gunn :

Then you don't understand lag. If you bump others unexpectedly then you don't care if they crash. It's just simple logic really, no opinion required.

How is it unexpected? I don't know about you but I watch how people are going to pass me, so I can setup a counter-attack. And if he isn't pulling out to pass, this can only mean two things, hes going to draft me, or bump me. I'll be prepared for either one.

Quote from tristancliffe :

Bumpdrafting would work at NASCAR speeds, so it could be used there. But the aero forces at karting, R/C and even BTCC levels are simply not strong enough to allow bumpdrafting. The increase in speed either driver would get in those categories from it would be so miniscule that it just wouldn't work.

Can you share your definition of bump drafting? I just want to make sure we are talking about the samething here.

Quote from keiran :

TagForce I really can't be bothered arguing the fact across it is not done in single seaters, it's not done in touring cars, karting, r/c racing.

I'm sure somewhere in the MSA rule book it says contact most be avoided if possible. I really don't think you watch things like BTCC properly and see that they are just running close to each other and not pusing each other along

You go find us some pictures of single seaters bumpdrafting.

Nice read for people who don't think bump drafting is idiotic
http://www.thatsracin.com/mld/ ... cin/archives/10938272.htm
Stright from a Nascar type person to



Keiran

http://www.racing-reference.com/driver?id=pettyky01

Yea, that's really working for Kyle. In the last 749 races he entered, hes won 8.

Bump Drafting wouldn't be so bad in NASCAR if it wasn't for the aero package / restrictor plate combo. They just can't afford to let off the gas, which causes a lot of accidents. Who is to blame?

Quote from Vain :

Well, in most LFS leagues they are selected in a qualification and a sprint race. And on other online servers they are selected by either qualification or finishing order of the last race.

Vain

Yes I understand that, but it still doesn't keep a driver from bump drafting. There are just so many situations that bump drafting can benefit the drivers that are doing it, it’s not really worth getting into it. I just used that one as an example for my argument.

Quote from Vain :

So bumpdrafting is a technique to close up on other drivers you are elsewhise unable to beat in direct comparison because you are slower?

Should have added: If it was a head to head race, obviously the better driver would win. But as many of us know, the best driver doesn't always win the race. Sometimes it's the better team.

Edit: forgot an s on sometimes.

Here's a little bit of a preview of what I've been working on lately. This is my team's current skin for the XFG. Still not fully completed, still a little bit of re-aligning to do, some text changes, roof/rear needs some flash on it. I also put in some custom dds files that I made. I edited the grill, and headlights. Mostly just tinted, but the headlights have some decals on it to follow the stripes, I think it gives it a bit more of aggressive look. Anyways, enjoy and feel free to comment, I like feedback.

http://www.tweakstur.com/aline_skin_preview.jpg
http://www.tweakstur.com/aline_skin_preview2.jpg

Quote from Vain :

tweaK_05:
So bumpdrafting is a technique to close up on other drivers you are elsewhise unable to beat in direct comparison because you are slower?

Vain

What if he started poll, and you started last? Doesn't mean hes faster than you, he just had a better position. And thats what happens most of the time in karting, as the starting position for the first heat is randomly selected.

Quote from cgrassham :

Name some series then apart from NASCAR. I used the three "biggest ones" as you say as a good example of where it isn't used, nothing more. As I said above I watch other series too and its not used there.

Like I said earlier, it’s being used all the time in karting; I've seen it being used at the local track stock car track and the local road course with the BMW series. Just because it's not on TV, doesn't mean it's not being used. As for NASCAR, I wouldn’t even really call that bump drafting, it’s more of a “If I let off the throttle, It’ll take another lap for my car to regain its speed. So I’ll just bump the person in front of me instead.”



$rant_topic = "bump drafting";


echo "$rant";


Essentially what I'm trying to get at here is that bump drafting is very useful technique for cars that are very momentum driven, such as the XFG, as its underpowered engine can only pull the car along for so long. When you start racing the XFG, you are required to be on top of your game constantly, and being on top of that sometimes isn’t enough, as the driver in the lead is also on top of his. So when you’re racing against someone that’s close in skill level to yourself, you won’t be taking 1 second out of the 4 second lead that he has on you. You’ll be lucky if you get a quarter of that, and in sprint racing, there’s usually not enough laps to close that gap by just out driving someone. Drivers are forced to use another technique to close the gap between their car and the leaders. This technique is bump drafting. Although it can be risky if not done properly, bump drafting has a lot of benefits, but the main one is the extra boost in speed. This helps with closing the gap on the leader with out forcing the driver to be put under all the pressure of becoming the fastest car on the track. This also saves on tire wear and concentration, allowing the driver to maintain the amount of traction and focus he had before he started bump drafting, which will be crucial when it comes time to pass. I know all of this from experience. This is all stuff I had to over come as driver over the past 8 years of my career.

Hopefully that is understandable, my writing skills are not quite up to par due to my lack of sleep.

Quote from banshee56 :

I beg your pardon. Here in the states, 4-stroke (206cc Briggs & Stratton) karts make 5.0hp, bone stock from the box. Once they have been tuned to the rules (even in "stock" class), you can easily get 10.5 hp from one. And the common weight class for the "Lite" classes is 300 lbs (136 kg). If set-up properly, these 4-cycle karts are anything but slow. I will give the 2-cycle karts props, though, as they are mad fast.

Almost exactly the same as Canada. Except we run 6.5hp Honda's (GX200). We mod these to the specs in the rule book and they put out around 10hp. Our light class is 340lbs (154kg), and these karts can hit about 70mph. If we had the track, we'd probably be running 125cc Rotax, but since no one around here wants to sit down and put the money into a kart track, we'll race what we can. I'll try out this mod and see how it is. But for a karting league to be started up, we need to see karts become a part of LFS (without modding)

These two buttons should be used especially when you don't see the car that was behind you just before you started braking, saves a lot of accidents from ever happening.

Quote from cgrassham :

Most motorsports I watch never use bumpdrafting, I'd never heard of it until today, and it seems its only used in a tiny number or Motorsports. I mean, F1 is my favourite sport and could you imaging it being used in that? The danger would be immense! same goes for Champcar or the IRL.

I would like to say that I think its a stupid idea and the people who like using it have to ask themselves, have the other users I'm doing this to even heard of it and would they appreciate it. Its ok saying, bd is fine, whats the problem!? Well I wouldn't appreciate it, especially if I've never even heard of it before. I'd just assume its some n00b who hasn't realised that if he can't get past that he may have to back off before he hits me.

Like TagForce said, there’s a ton of other motorsports where it is used. And using the 3 most popular ones where it isn't used, doesn't really prove anything besides the fact that bump drafting can't be used in anything open wheel, with weak/no bumpers, for the obvious reason. And if this is mostly what you watch/race, then surely you're going to think it’s stupid.

Yes, Wrecking is also another technique used to win races. But usually people don't get away with it. Thats why no one besides a few special little kids in demo use it, and they never seem to get away with it. I just don't see why people are affraid of taking a chance that can only benefit them if the process is done right. I mean you enter a race to get a chance at winning the race. The whole race is a chance, everytime you brake, it's a chance, everytime you take a corner, it's a chance, everytime you bump draft, guess what, it's a chance. And that's just another chance that's already on my "WILLING TO TAKE A CHANCE ON" list.

Bump Drafting is one of the most useful techniques, plain and simple. Me and my cousin used it all the time in karting. We'd pull away from the pack, and then battle it out or we'd team up and work our way through all of the traffic. This technique has transferred over to LFS without a problem. We both understand when to brake, and when not to bump. Hell, we even bump draft in corners. Do I do it to people I don't know? Yes. Is it controlled? Yes. Has there ever been an accident because of it? Yes, mostly when people slam on their brakes. Maybe if people started to realize that when they are race there’s going to be contact. I'd rather it be controlled then "non-intentional". Thats my 2 cents, and my first post.