MY project, just got sweet - Page 3

xx4-nutter · #41 19-10-2006

would it be hard to have the motor end bell up ?. and try to work some neat transmission round it. would it have any set backs ?

Rob Fitzgerald · #42 19-10-2006

Just think about this for a minute

You have the motor in the car endbell up - you are jumping the car and the motor is spinning - what happens ?

email your answer to whyamipontinginthewrongdirection@thisjump.com

xx4-nutter · #43 19-10-2006

its true i am an idoit

Rob Fitzgerald · #44 19-10-2006

You are not an idiot at all.

If people didn't come up with new ideas then we would be stuck racing the same boring old things wouldn't we

Southwell · #45 19-10-2006

Would be an interesting gearbox mind

BenG · #46 19-10-2006

If you have the motor end bell up think about the weight distribution, and the high C of G. Innovative idea still.

I am thinking, only thinking mind, of making the wishbones part of the aerodynamics, as in they generate downforce, so that the wing can be a little more refined

Divefire · #47 19-10-2006

Oh dear, this might not go down so well but bear with me…

Aerodynamics, down force, on a scale buggy doesn’t really exist. Ok now before you throw your chair at me, let me explain a bit.

Yes I know, body shells and wings make the cars handle differently, and that’s a fact but it happens because of the drag being produced not because of downforce. Why not? Well because air density increases with speed, and at the speed the buggies get up to, plus their rather small size, it’s not enough to produce downforce. There’s not the surface area or the speed there.

So how are your normal wings and bodies producing more grip? Basically drag. If you look at a high downforce wing or a touring car body that people say gives more front end, usually they have a very steep front profile. This produces the drag. Drag itself doesn’t produce more downforce but what tends to happen is a cushion of air is built up, increasing the density more then in other areas and thus pushing the car down a bit. Of course at this point the air is having trouble flowing over the car so it isn’t terribly efficient but that doesn’t matter so much on scale racers.

So how does this relate? Well making parts aerodynamically efficient is a bit pointless in this scale. Yes if you’ve got a giant front upright you’d want to try and find a way to minimise it’s drag impact, but that’s about it. Making things like wishbones so they’re an aereo device won’t help, they’ll be no better then a conventional one.

Of course on the subject of wings there is a school of thought that says a multi element wing would produce some efficient downforce, but it would be rather fragile and at the end of the day be no better then a drag inducing wing for our purposes.

Sorry if that comes out a bit know it all, and feel free to argue, aerodynamics is a black art at the best of times. Now if we could just come up with some decent body shell cooling ideas…

Oh on the subject of the actual car design itself, I’d go with mass centralisation, a balanced left to right weight distribution and then find out what front to back weight distribution works best, probably around 55/45. And then there’s suspension geometry and all that fun stuff to play with… Good luck!

BenG · #48 19-10-2006

wow, matey, you know loads on aerodynamics. Do you have MSN? If so, could you PM me ur addy? I need to talk to you regarding some ideas I have.

I have taken into consideration yuor points. thanks

Richard Lowe · #49 19-10-2006

I must disagree with the differences between wings (in off-road at least) being purely drag, they do create a downward pressure of some sort. Different sized wings make a big difference to how the car behaves in the air, big wing on the back = nose up, front wing = nose down.
I don't see how that could be caused by drag alone, as surely with the wings being rigidly attached to the car the drag relative to the forward movement acts on the whole car. There must be downforce of some description happening or we wouldn't see different behaviour in the air by altering the wings at either end of the car.

BenG · #50 19-10-2006

ok, now I am confused LOL

xx4-nutter · #51 19-10-2006

i can vouch for what rich has said there, my losi xxx4 used to be a pain in the air at landing on the arse end, i dropped a massive yokomo bx wing on it fully uncut and it made the car perfect in the air ! = very happy bunny !

Cooper · #52 19-10-2006

http://users.telenet.be/elvo/

chapter 7

PaulRotheram · #53 19-10-2006

Quote:

Originally Posted by xx4-nutter

i can vouch for what rich has said there, my losi xxx4 used to be a pain in the air at landing on the arse end, i dropped a massive yokomo bx wing on it fully uncut and it made the car perfect in the air ! = very happy bunny !

That makes no sense.. if you are struggling with the car being nose high, how can an even bigger rear wing help? it should make the problem worse

xx4-nutter · #54 19-10-2006

that is one of the best sites on set up ive ever seen
very in depth and explains everything

xx4-nutter · #55 19-10-2006

Quote:

Originally Posted by PaulRotheram

That makes no sense.. if you are struggling with the car being nose high, how can an even bigger rear wing help? it should make the problem worse

nose dive sorry, i also shifted the cells to the back and changed the wing

k£v!n · #56 19-10-2006

yeah that site is very helpfull, its intresting ot read too!

kev

Chris Doughty · #57 19-10-2006

I agree with the 'moments around the CoG' theory, that drag above the CoG will turn the car onto its back wheels as Elvo points out.

I also agree with the 'air damn' theory, if air hits a surface and is forced upwards, there must be a force downwards that the air is giving the car (every action has an equal and oposite reaction)

but low pressure and high pressure enduced downforce is not really that much of a deal at our scale.

BenG · #58 19-10-2006

ok dokey cheers, I have a few ideas now

Divefire · #59 19-10-2006

Yeah this is the fun part of aerodynamics, we just don’t know and I have to stress I’m an amateur at it. Don’t have a nice doctorate in it or anything…

Anyway, Richard you’re quite right in what you’re saying, I was just illustrating the differences between efficient aerodynamics, ie a multi element wing with negative lift properties (an aircraft wing upside down sort of thing) and the scoop wings we tend to run on the buggies. If you have a big wing, or a front wing then yes you’re going to catch more air, pushing you down some as you drive forward, but to does have to be at quite an angle to have an effect, thus the drag being caused in that way.

Richard Lowe · #60 19-10-2006

I understand what you were getting at before, I'm no expert either lol

That's half the fun of this hobby, you never stop learning things