36 replies to this topic

[Rosssco]

My (even more) basic understanding of the use of small front splitters is simply to reduce front end lift at high speed (being mid-engine, the front is already light, and the clam is curved at the leading edge) , not to produce any discernible front end down force..

[BadCop]

@Badcop

But for someone who just tracks/races their car then this info could be a great mod, though it's worth bearing in mind that this was in conjunction with a huge 10:1 chord wing on the rear.

 

 

Something like my new little carbon friend here

 

 

 

 

here is the full lecture script if someone is interested.

Its in german but Ithink you can get the facts with the equations and drawings.

 

http://www.aer.mw.tu...gsfzge_Kap1.pdf

http://www.aer.mw.tu...gsfzge_Kap2.pdf

http://www.aer.mw.tu...gsfzge_Kap3.pdf

http://www.aer.mw.tu...gsfzge_Kap4.pdf

http://www.aer.mw.tu...gsfzge_Kap5.pdf

http://www.aer.mw.tu...gsfzge_Kap6.pdf

http://www.aer.mw.tu...gsfzge_Kap7.pdf

http://www.aer.mw.tu...gsfzge_Kap8.pdf

http://www.aer.mw.tu...gsfzge_Kap9.pdf

http://www.aer.mw.tu...sfzge_Kap10.pdf

[Nev]

Wing looks very big (and expensive!), but wouldn't it be better placed higher up in the full airflow?

 

Is this your car with the A20NFT + twin scroll turbo in it?

 

Edited by Nev, 03 January 2018 - 04:20 PM.

[Doctor Ed]

Dominik, the thing youve posted with ride height is for proper ground effects... which is a pretty super-specialised subsection of underbody aerodynamincs, and really doesnt pertain to 99% of racecar aero.

 

not to say ride height isnt relevant - indeed for diffuser function a similar relationship with ride height vs downforce can be plotted. just that youve posted some pretty specific stuff there relating to ground effect aero, and it can be a little misleading to generalise it.

 

in any case, a splitter is simply designed to take the pre-existing high pressure zone acting horizontally on the front of the car (drag) and add a vertical component to it (downforce) by providing it a flat surface to act downwards upon. whether by design and velocity change a negative area on it underside is simultaneously created is a bit hit and miss. the main thing is the high pressure zone acting downwards on it, and this isnt particularly ride height dependant. what happens under the splitter is a differnt story, and get complicated quickly. either way a proper splitter should be able to be stood upon. they are by no measure designed to 'add drag' (why would you do that!).

 

imho a vx/lotus could benefit from a 'proper' splitter, along with turning vanes behind the front wheels, plus a proper diffuser. im a bit baffled as to why the diffusers for these cars are often made so small and steep, personally i dont think anyone really make a proper diffuser at all for these.

 

 

Edited by Doctor Ed, 03 January 2018 - 04:27 PM.

[Acidpopstar]

Thanks for that Ed. I realise we’ve done off topic completely here but it makes good reading and good for thought. I’ve not bought any splitter or diffusers as I haven’t found any that really look right and that would actually do anything. What splitter is that on the pic above? And what are turning vanes? And what would a ‘working’ diffuser look like? Sent from my iPhone using Tapatalk

[Doctor Ed]

massive topic man, but to keep it quick, the above splitter is DIY, but in principle theyre all the same. big, flat, protrude out the front quite a bit, and can be stood on. discharging into the wheel well is optional. turning vanes are curved plates on the underfloor designed to steer airflow. can be used to removed dirty air from the wheel well, can create a small veturi like zone, and can be used to create vortices along the underfloor sides to seal inflow from the side o the car off. a 'proper' diffuser is l-o-n-g and gradual, and starts ideally around the drivers ass. the peak low pressure zone with a diffuser occurs where it very begins, no point having that right at the back of the car. its possible on the lotus to start a diffuser in front of the fuel tank where the sheer panel mounts at the front, and draw it all the way through to the back. shift the exhaust muffler a little, and you can create a huge diffuser

 

(and a tip if doing some reading - dont nec look to f1 for inspiration, theyre hamstringed by rules that spoil proper design, although the prcinciples are the same)

[Nev]

There was an ex-VX220 owner on here called Alex Barr who used to work for Ferarri and now works for Force India, specialising in aero for them. Shame he sold up really.

 

Edited by Nev, 03 January 2018 - 07:11 PM.

[BadCop]

Ed, you're right - how I wrote it was confusing.

 

Let me put it that way:

 

I have owned 3 Splitters, unfortunatelly no Eltech.

But my experience with Dempert clone, MS Edel and a selfmade Front-Splitter was exactly what Nev wrote:

No effect what so ever - until you lower the car

 

Without a splitter and the car still on low ride height the downforce is also almost gone.

 

 

 

I understand a "real" frontsplitter like you showed in your post would get downforce independently from the ride height.

But from what Nev and I experienced on the track all those available splitters like Eltech will not work in Standard height.

 

Perhaps we only see some kind of ground effect with the splitter creating a lower pressure zone on the floor like an airdam.

 

- Or any other weird correlation

 

Really the only constant I experienced in my "empirical aerodynamics research" is:

Aero is not intuitive - you can't predict anything from looking at it.

 

But I want to share what I found out so far

[siztenboots]

at work we used to run the lotus model in one of our wind tunnels

 

at southampton they have a better rolling surface and there are some good published papers about bluff vehicle and diffusers

 

https://eprints.soto...und_effect..pdf

 

 

larger scale model  lol

 

 

[Dan r]

Is that Kingston uni? I did auto engineering there in 2000, the wind tunnel looks about right and there was a silver s1 Exige with telemetry to play with there as well, there wasn't a model of it when I was there though.

[siztenboots]

Is that Kingston uni? I did auto engineering there in 2000, the wind tunnel looks about right and there was a silver s1 Exige with telemetry to play with there as well, there wasn't a model of it when I was there though.

 

yes it is 

[Madmitch]

This is a seriously complex subject but I think it fair to say that you cannot hope to achieve real results from front splitters and rear diffusers on a road car because both rely on low, and relatively fixed, ground clearance to achieve meaningful results.  That is not possible on a road car because of the need for better ground clearance plus suspension supple enough to absorb bumps and hollows, unlike track cars which run on very flat surfaces and have very stiff suspension with little movement.  Just fit what looks good!!  

[TFD]

So... how about the Eltech seats? Anyone got them?

[harboged]

So... how about the Eltech seats? Anyone got them?

 

I do. Bought one like three years ago and I'm quite pleased with it but I haven't tried any other aftermarket seats so I can't compare. Definitely more inclined than the OEM seat and a bit more narrow. Good thing is that the side supports easily can have thicker pads mounted to them in case you want to make the seat even narrower. At that time the Eltech seat was a lot cheaper than the Tillett, don't know how it is now.

 

I like the build quality but I have never seen a Tillett seat or similar, so I don't know how they compare. But I was a bit surprised by the fact that you have to drill the attachment holes yourself to attach it to the seat runners. I was a bit nervous to mess it up and get the holes misaligned or something. A seat with integrated nuts would be preferable from this point of view, but would mean more trouble if the nuts start to rotate. Besides, bolts that run through the seat mount and seat and are clamped together with nuts and washers maybe result in a stronger structure compared to integrated nuts in the seat?

 

Eltech has upgraded the seat since I bought mine, don't know what the differences are though.

[ianrm]

My Front splitter arrived today. First class quality.

[pete-r]

Can you get some detailed pics?

[ianrm]

Can you get some detailed pics?

 

 

Soon