Weird idea for motorcycle design

[andreis]

Long post ahead, beware..

Ok, I'm no expert on the matter, BUT seeing as how a lot of cars these days use aerodynamic forces to generate downforce on the tires as the speed increases and thus increase stability & cornering ability, I don't see why it shouldn't be used on bikes as well...
So, here's a few pros & cons for it that I've thought of :

Cons:
1. Difficult to properly implement
2. Weight increase of the bike
3. Weird looking at for the first few designs..

Pros:
1. Extra traction when cornering as speed increases
2. Added stability in a straight line as speed increases
3. Possible increase in breaking forces when required

I thought of small wings on the bike. Trouble is, you'd have to mount them on the wheels in order for them to be effective (they would not have any effect on the suspension behavior this way and the forces generated could easily be distributed to the tire). On top of that, you'd have to somehow make them tilt so that they would always be parallel to the ground. That way, they would not generate lateral forces when the bike is tilted over, but only downforces. You could use them when braking also, as one of the few other forces that can be used for braking other then the friction ones from the tires are aerodynamic ones (which you generate as you position yourself higher in the seat and act like a parachute). You the wings would change their angle like an aileron for a car, which would produce either supplemental drag or extra downforce on the tires..
I realize that it would be hard to implement (probably VERY hard), as it requires some sort of motor force at the wheel and some sort of pivoting mechanism which might be very complex, as it is required to withstand the forces generated.. then again the motor force could be transmitted from some other source.
Anyway, this is why we've got engineers in the world, to solve these kind of problems, right? I just think it would be great to use something like this..:rolleyes:

[andreis]

Oh, and I've found this on the net about it..
http://books.google.ro/books?id=84hF-qoR5I8C&pg=PT151&lpg=PT151&dq=front-end+winglet+motorcycle&source=bl&ots=FYA7tNMfNl&sig=N0l89IdQxWwfDweWxEJqaE_xGL8&hl=en&ei=MFoSS5btFtD-_AaIpJ2nBQ&sa=X&oi=book_result&ct=result&resnum=8&ved=0CCYQ6AEwBw#v=onepage&q=&f=false

[andreis]

Hm.. okay, another con is that if the wings were to tilt, the extra down force would also induce a tendency of the bike to lean further and further as you lean into the corner.. But this could be countered by somehow making the point where the downforce is applied placed as low down on the wheel as possible. If, for example, the wheel were to have on the bottom end some sort of rotating mechanism through which downforce could be applied..
Better yet, some sort of magnetic setup..

[zsv650]

i cant see the wing wheel's working first bit of lean you get the wing would touch down and you'd be off the best aerodynamic's on a road bike was the busa but nothing to shove you into the tarmac like car's.

[andreis]

Not if the wings tilt. That would not be an issue. When you lean, the wings would always stay parallel to the ground

[yorkie_chris]

Mudguards are already designed to create downforce. That's why 'busa one is pig-ugly!

[zsv650]

a small wing would not create that much downforce anyway if you look at the cars theyve got 5.5-6 foot of wing pushing it down.

[andreis]

I mean something like this:

[zsv650]

That's why 'busa one is pig-ugly!
i'd still have one :cool:

[andreis]

Oops, appears that I don't know how to properly attach pictures.. Oh well..

@YC : yeah, I agree about the 'busa being that way.. But mudguards don't tilt against the bikes tilt, so when the angle is above 45 deg, they actually do more harm..

[andreis]

About the downforce generated, I gotta say, I don't really know about that.. I mean, I've seen the formula for it, but I can't really estimate what it would turn up to.. But come on, the F1 guys get to something like 5-6 lateral g, while the tires on bikes can withstand something like 1-1.1 g at most (I think.. not sure). And the difference is exactly in the downforces generated and the contact patch size (relative to the actual weight).
Maybe we won't get 5-6g's, but how about 2?

[sunshine]

your saying the wing tilts so to continue to produce downwards which in theory is only going to push bike lower into the corner causing it to lean to much into the corner or maybe just cause a lowside

bikes are already designed to make them fast as stated about to 'busa, many other bikes have means to keep there cornering speed and traction to help them round corners.

[andreis]

Yeah, I agree, but if somehow the downforce would be directly transferred to the tire or the wheel rim, then it would be awesome! .. Daydreaming...

[Mr Speirs]

I don't think it is much of a priority as the bike does lean, meaning that you can only optimise for one angle really, anything else and it isn't going to have positive effect.

The other thing is why doesn it need to be only on the wheel? You say its because of suspension but cars bodys are designed as the aerodynamic downforce generators yet they push down on the suspension and still have the desired effect.

Also most bikes are capable of knee down/elbow down kind of lean angles so how much more do you want to go?

[jambo]

Given that we want wheels as light as possible to reduce gyroscopic forces and make the bike turn faster, complex systems on the wheels are probably off the menu for now.

Cars suit wings well because in a corner the car's weight is pushing towards the outside of the corner, but the down force acts stright down, helping the tyres to grip.

A motorbike's forces in corner are rather different, with there being no surface that can offer force straight down, and any forces acting in line with the bike working at over 50 degrees to the vertical on a MotoGP bike mid-corner.

Aerodynamics play a big part in stabilising the bike on the straights though.

The other major problem with aerodynamics and bikes is the rider, who refuses to sit perfectly still and messes everything up.;)

Jambo

[muffles]

Interesting thought, I just had a quick think about it and I think the problem is - as mentioned above - the lean angle of the bike.

Bikes need lean angle to turn through a certain radius. Cars need the angle of the front wheels turned, to turn through a certain radius.

I think at the moment the limit of the tyre lean angle *can* be reached, so what you'd need is (in motorsport at least) to increase the amount of lean available on the tyre. It's not available now because they would low side - and they would low side because the tyre didn't have enough grip (which would be offered by these wings).

It'd be the same problem if cars were on full lock while making the same turns, increasing the downforce wouldn't help without increasing the lock and giving them a way to use it.

It might be useful as a safety device though.

Oh and I am conveniently ignoring all Jambo's real-life points in favour of the pure theory answer :)

[andreis]

Found something about the subject (apart from the google books). Apparently some nut job did try it :) Linky:
http://www.motorcycletrader.co.nz/View/Article/Rodger-Freeths-Aerofoil-Viko-TZ750A/236.aspx?Ne=145&N=4294967266&No=135

They don't actually say about the benefits (or lack of them for that matter), but it's an interesting read nevertheless

[yorkie_chris]

Given that we want wheels as light as possible to reduce gyroscopic forces and make the bike turn faster, complex systems on the wheels are probably off the menu for now.


Why would wings be on the wheels? No gyro forces if they aren't spinning.

For that matter they wouldn't have to be on the fork lowers, so not adding unsprung weight either.

[ophic]

How about fan blades instead of spokes? At high lean angles, the wheel would be blown into the ground, increasing traction? (perhaps :?)

Only for use on track tho, where you're doing more turning one way than the other. Or go down the route of adjustable pitch blades.

[andreis]

Hahaha I love it! it would be a real chopper! (couldn't help it..)
The only thing left is to actually drive fast enough to provide sufficient spin speed