Wishbones attachment question !

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firasf1dream
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Joined: Fri Apr 18, 2014 8:26 pm

Re: Wishbones attachment question !

Post by firasf1dream » Sat Jul 26, 2014 11:15 pm

the angle of attack ?! no way ! it's the article 10.3.3
the angle of attack is 0 i guess the airfoil is symmetrical isn't it ?!

then how the angle is defined if not in that section ?

and it says there must be 100mm between the upper wishbone and lower wishbone which makes sense when looking at it in the picture because the bulkhead dimensions are 300cm width and 275mm to 300mm height !

marcush.
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Re: Wishbones attachment question !

Post by marcush. » Sat Jul 26, 2014 11:25 pm

firasf1dream wrote:the angle of attack ?! no way ! it's the article 10.3.3
the angle of attack is 0 i guess the airfoil is symmetrical isn't it ?!

then how the angle is defined if not in that section ?

and it says there must be 100mm between the upper wishbone and lower wishbone which makes sense when looking at it in the picture because the bulkhead dimensions are 300cm width and 275mm to 300mm height !

10.3.3 No major axis of a cross section of a suspension member, when assessed in accordance with Article 10.3.1, may subtend an angle greater than 5° to the reference plane when projected onto, and normal to, a vertical plane on the car centre line with the car set to the nominal design ride height.

read again - cross section no angle greater than 5° to the reference plane when projected normal onto a vertical plane on the car centre line so you look to the cross section from the side of the car... its the angle of attack.

the wishbone inclination is not defined in the regs directly -of course there are Limits to were you can physically put it given the tub dimensions mandatory in that area .

angle of attack has nothing to do with symmetry of the Profile.

firasf1dream
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Joined: Fri Apr 18, 2014 8:26 pm

Re: Wishbones attachment question !

Post by firasf1dream » Sat Jul 26, 2014 11:31 pm

you're right, my mistake, yes the angle i see many cars have it which leads to the hole of the side pods

so what about the angle of the suspensions how is it defined ?!

marcush.
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Re: Wishbones attachment question !

Post by marcush. » Sun Jul 27, 2014 12:14 pm

again..
this angle is defined by YOU the cars designer !
There are Minimum bulkhead dimensions as you mentioned above and there is physical Limits of where you can actually put Suspension Points (even if you Resort to virtual pivoting Points) -there is also a Limitation on Suspension anchoring Points so you cannot just up the Count of Suspension members as well.
But apart from this you are left with the Basics:

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firasf1dream
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Re: Wishbones attachment question !

Post by firasf1dream » Sun Jul 27, 2014 12:45 pm

yes i was searching and reading and found out that there is no rule for that, the design will define it the height from the reference plane, the wheels, the wheel's hub etc,
before they used to make it horizontal because there was a keel still but now not

thanks for the info :)

marcush.
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Joined: Tue Mar 09, 2004 3:55 pm

Re: Wishbones attachment question !

Post by marcush. » Sun Jul 27, 2014 4:22 pm

firasf1dream wrote:yes i was searching and reading and found out that there is no rule for that, the design will define it the height from the reference plane, the wheels, the wheel's hub etc,
before they used to make it horizontal because there was a keel still but now not

thanks for the info :)
again -no
The keel was there for the Wishbone not the other way round mate...Teams realised aero potential in Lifting the tub higher and higher to reduce blockage between the front tyres caused by the tub.
Unfortunatelly this did not only compromise CofG height but also geometry -so you either incline your wishbones and compromise scrub and roll centre Location or live with one or two keels or something similar to attach the lower wishbones to.
I think the first to use twin keel was Sauber(or the stillborn Honda by Harvey Postlethwaite) -I´m not sure where single keel was found for the first time-maybe that was more of a iterative move towards the single keel (maybe Ferrari?).

firasf1dream
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Re: Wishbones attachment question !

Post by firasf1dream » Sun Jul 27, 2014 5:16 pm

yes that's what i meant the keel is there for the wishbones

ok so when the tub got higher than the cockpit where the driver sits they removed it which led to incline the wishbones

marcush.
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Re: Wishbones attachment question !

Post by marcush. » Sun Jul 27, 2014 5:56 pm

i think Toyota started that trend a few years ago ,doing away with the one or two keel solution (with Renault developing a v-keel solution).
They were the first ones to Sport those massively inclined wishbones.
The latest Perversion of this trend clearly the ferrari pull rod which almost entirely relies on track width change in bump for creating any damper and spring displacement at all...with them still arriving at a(nearly) competitive package it tells a Story about importance of suspension geometries in todays formula 1 .... :wtf: I ´d think it´s more important to have Installation stiffness than anything else -be it geometric roll centre or whatever.

xpensive
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Re: Wishbones attachment question !

Post by xpensive » Sun Jul 27, 2014 6:02 pm

Perverted indeed, 2013 car on the left, but the pull-rod (4) is almost horizontal on both cars.

Image
"I spent most of my money on wine and women...I wasted the rest"

firasf1dream
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Re: Wishbones attachment question !

Post by firasf1dream » Sun Jul 27, 2014 7:32 pm

yes the pull rod totally changed !

mep
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Re: Wishbones attachment question !

Post by mep » Sun Jul 27, 2014 9:57 pm

marcush. wrote:I do not agree with Mep These Points are fixed or set in Stone . You can of course specify multiple attachment variants in your original design without any compromise .It´s not like you have to cut a serious hole into the tub to allow for adjustability -if done correctly all you Need is a pit in the outer Shell were your alternative Suspension pickups will all fit in -allowing for considerable Change in antidive geometry and also movement of rollcentre Position .
Yes, you could do that. But still you need to predefine those points in early design stage. When you are on the track later you are fixed to those predefined positions. It’s not like having a lot of setup opportunities and it will always come with a certain compromise.
firasf1dream wrote:and it says there must be 100mm between the upper wishbone and lower wishbone which makes sense when looking at it in the picture because the bulkhead dimensions are 300cm width and 275mm to 300mm height !
No it does not. The chord length is defined to be max 100mm.

Btw. Now most teams use a design where the wishbone consists of a structural core carrying all the loads and a rather flimsy fairing around which generates the aero shape. What you see on all those pictures posted so far is the complete wishbone. This means that the flex underneath is much thinner, which actually allows it to flex. You should keep that in mind in your designs.

Also it makes sense to design the flex in a way such that it is not flexed when the suspension is in its mid range position. You can do the same with ball joints off course because both are limited in their maximum angular movement.

firasf1dream
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Joined: Fri Apr 18, 2014 8:26 pm

Re: Wishbones attachment question !

Post by firasf1dream » Sun Jul 27, 2014 11:01 pm

mep wrote:
Yes, you could do that. But still you need to predefine those points in early design stage. When you are on the track later you are fixed to those predefined positions. It’s not like having a lot of setup opportunities and it will always come with a certain compromise.
firasf1dream wrote:and it says there must be 100mm between the upper wishbone and lower wishbone which makes sense when looking at it in the picture because the bulkhead dimensions are 300cm width and 275mm to 300mm height !
No it does not. The chord length is defined to be max 100mm.

Btw. Now most teams use a design where the wishbone consists of a structural core carrying all the loads and a rather flimsy fairing around which generates the aero shape. What you see on all those pictures posted so far is the complete wishbone. This means that the flex underneath is much thinner, which actually allows it to flex. You should keep that in mind in your designs.

Also it makes sense to design the flex in a way such that it is not flexed when the suspension is in its mid range position. You can do the same with ball joints off course because both are limited in their maximum angular movement.
ok thanks a lot so i must put an aluminum core inside it with a diameter of about 5mm or a rectangular piece with a thinkness of 1mm might do the job inside the carbon fiber shape

mep
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Re: Wishbones attachment question !

Post by mep » Sun Jul 27, 2014 11:16 pm

Well, I have not said anything about aluminium. For sure aluminium would not be the material of your first choice. F1 structures are made of carbon, including the flex. The junction might be made of metal. However if it’s simpler for you, then you can make the flex out of steel.

Ali F1
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Re: Wishbones attachment question !

Post by Ali F1 » Wed Jul 30, 2014 7:33 pm

FirasF1Dream - Read my blog to help you find suspension angles (Geometries) !

http://www.ali-f1.blogspot.co.uk/2014/0 ... tries.html

You as the designer should calculate your geometries to find the angles of your wishbones.

marcush.
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Re: Wishbones attachment question !

Post by marcush. » Wed Jul 30, 2014 8:32 pm

You would at least try to create some Option for changing things lile roll centre height and anti dive or squat geometries especially when you don´t know the tyre you are goingt o use and if you have no experience or a legacy car /line of cars to base your new design on .

you can only do so much when moving the outboard Points ...but with the available crossection it seems entirely possible to design counter intuitive wishbones (for example with a narrow base as this years lower front Mercedes wishbone ) so i still stand to my Point-geometries are considered not that important -but make sure Installation stiffness is high on your priority list-so you have control over what Little movement there is.

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