Pastywagon sprint dates 2010 - Overall championship win!

[RobT]

Aero-efficient bumper back from paint.....well nice IMO, very smooth

Rear hinge for front floor ready for floor fitting - that is a VERY tough stainless steel hinge - had to buy some special drills to drill the bleedin thing - exact shape of front edge of floor can now be finalised now the bumper is back

This weekend should see the floor and splitter fitted.

Ave it

Rob

 

[m0rk]

Keep at it Rob. Bumper looks right - nice & tidy, but OE looking (far better than original)

How low will your splitter run?

 

[RobT]

Splitter will be 120mm off the deck - minimum ground clearance is 40mm but regs also state that no part of the car should touch the ground if the tyre bursts - so for me thats 70mm

120mm comes from the position of the rear floor support - using the lower wishbone brace was an efficient way to mount it - thats 120mm off the deck

Mk1 floor will be totally flat and made from ply - if it doesn't get smashed off then Mk2 will be carbon-foam sandwich with some shape to create a low pressure zone at the front axle line

Probably from these chaps: http://www.fibre-lyte.co.uk/cf/index.html (check out their Audi S2 and TT sprint/hillclimb cars)

Note: this will not work if your car has a normal 'wet' sump as it will get in the way......mine is dry sumped and thus has much more room below the engine - the lowest point on mine is the bottom of the gearbox bellhousing

 

[old 'uns]

how thick a plywood you plan to use Rob?
Foamex board any good? light, cuts with a Stanley knife ( other cutting knives are available! ), probably cheaper than wood
http://www.roberthornedirect.co.uk/...ath=107_2_89&gclid=CP25lszzkKACFRQulAodghjndw

ps...don't even mention you've got F2 wings, load of loonies on mk2 forum @ mo
you know what the Q's will be!

 

[RobT]

I was thinking of 6mm as this has quite a few plies but is not as heavy as say 9mm - which has no more plies, just thicker plies.

Thinner and lighter the better obviously - but it needs to be 'just' strong enough

Thinner than 6mm tends to be just 3 ply and probably not strong enough.

I dont know anything about foamex....whats it like?

 

[old 'uns]

used by sign companies from 2mm to 10mm comes in usual sizes up to 8' x 5'
very light, probably half to third lighter than equivalent ply?

 

[m0rk]

foamex is light... and about as flexible (or not)

Also - if you clip it, it'll snap rather than bend what you screwed it into

They make big signs out of it etc, some are aluminium skins sandwiching foam.

 

[RobT]

hmm....very interesting

so its a foam core with pvc laminates?

 

[old 'uns]

these might be worth a visit..samples maybe?

http://www.hotfroguk.co.uk/Companies/Mirage-Display

 

[old 'uns]

not a composite as such, i know nothing about the technical side of it, but for a trial its cheap before committing to carbon

 

[RobT]

these might be worth a visit..samples maybe?

http://www.hotfroguk.co.uk/Companies/Mirage-Display

spot on - I know exactly where that is - definately worth a trip - cheers, very useful

 

[old 'uns]

made from PVC so in your territory?

 

[RobT]

PVC is fine - a bit of ali tape where its near to hot things - if its as strong as 6mm ply and lighter, at the price that it is I will give it a try

although I see they also have ali composite board......I'll see what that sign place has to show me

 

[RobT]

Mk1 floor and splitter design:

Cardboard template finalised - black line is bottom of bumper, red line is overall plan of bumper (i.e the widest / biggest section). Plan of bumper is relevant since rules say

"front spoilers / air dams / splitters are allowed below the level of the wheel centers up to 15cm beyond he overall plan periphery of the existing bodywork"

So I am no where near 15cm at any point.

Fitted to car:

I have taken it to the limit of the front track, 3" forward at the front/middle, and the rest is join the dots with a smooth curve.

Dead pleased - looks well mean. Transfer to foamex or ply next job.

Now its on, I can see where the venturi's are going to go for Mk2 next winter.....oh yes......

 

[F2 Stu]

Ace stuff!

who needs CFD & wind tunnels!

 

[RobT]

well (a) it might not work and (b) it might get broken off

but its a start at least - looks a lot like stuff I have seen on other more professional racers so maybe it wont be far off and at least a bit functional

with blocking off the lower bumper opening and fog light holes, there is now quite a large 'slab' of uninterrupted airdam above the splitter (well there will be as soon as I have filled the gap between floor and bumper with PVC sheet) which will create the positive pressure zone above the splitter.....and maybe some downforce......heres hoping

and the whole lot is fastened to the chassis, so any effect might be transmitted to the wheels rather than bending the bumper

its designed based on observation of other cars and an excellent book called 'competition car aerodynamics' by Simon McBeath

also there was an excellent series of articles in Racecar Engineering about a hillclimb mini that they had in a wind tunnel and were trying bits an pieces out

http://www.carbonweezel.co.uk/testing.html

 

[Willie]

Great thread.

Good luck this year

 

[RobT]

talking to a mate 'in the know' today revealed that probably 9mm ply was the thing to go for as far as ply is concerned - 6mm typically only has 3 plies in it whereas 9mm has 5 plies and is much stiffer - 12mm also has 5 plies, just thicker plies, but is too heavy.

But a specialist wood place near here says they have 5-ply 6.5mm in stock.....checking it out tomorrow along with the sign production place for info on foamex board

Quick calculation this afternoon:

Assuming a density of plywood of 600kg/m3 (0.0006kg/ml)

My design in 6mm ply=3.01kg. In 9mm ply=4.52kg.

The ibiza diesel van plastic engine undertray I have been using=2.5kg

So I am not as worried as I was about the weight penalty of this exercise.

 

[old 'uns]

just found a 2' x 2' piece of 6mm foamalux board, weight 1.4kg so maybe not so light compared to ply as i thought?

 

[RobT]

I found some density figs on the net also which said 0.5-0.7 specific gravity - thats pretty much ply weight so like you say, no much in it perhaps