SEAT Ibiza - rwd turbo
Discussion
AER said:
Max_Torque said:
Without putting the whole car into CAD...
Go get it scanned somewhere and I'll help you set up a CFD case in OpenFOAM...So, more progress on the wing plates, now with some "profile" to them, although obviously just mdf in primer as patterns for now, and without finalised Radii etc:
Looking OK i think?
(have left enough space to put an active lower flap across that stalls the main wing during braking etc at a later date.........)
Olivera said:
Max Torque, what's the reason for going RWD rather than 4WD?
4wd is for poofters.......... ;-)More seriously, the car was built as a rally car, so if you're 4wd you're competing against pukka WRC cars and you aren't going to beat those! The 2wd classes were much freer and there were some nice advantages in being 2wd (including much lower weight limits etc) the main one being that i didn't have to spend £60k on a fully active "3 diff" transmissions system from Xtrac!
CamMoreRon said:
I don't mean to piss all over your lovely end plates with my fire hose of half-formed ideas based on about 10 mins experience, but I honestly think your wing will be little more than a parachute!
The trouble I had getting a relatively softcore modified NACA profile to work with my hatchback tells me that yours has way too much curvature to keep flow attached. I understand it's cool because #BTCC but do you reckon it's going to work? Might be worth sticking a big relatively flat single plane on there, especially if your height is limited by regs.
Remember this is a "Low speed wing" not an F1 car wing or aeroplane wing! It needs to work between around 50mph and 120 mph max. That means a deep chord with high curvature. Your typical wing you see people put on race cars often look like it's come off a Boeing and works well at around 200mph with a commensurately good L/D ratio, but the only downforce it provides in the real world is the weight of the wing itself....... It's also worth noting that the wing i have from the Mondeo BTCC is a combined wing anf gurney flap. It's difficult to tell from the pics, but it has a relatively shallow camber on the underside, and the large rear vertical section is designed to effectively "stall" the top side.The trouble I had getting a relatively softcore modified NACA profile to work with my hatchback tells me that yours has way too much curvature to keep flow attached. I understand it's cool because #BTCC but do you reckon it's going to work? Might be worth sticking a big relatively flat single plane on there, especially if your height is limited by regs.
Of course, it was designed with CFD and optimised in a wind tunnel for the BTCC car, which as it was a mondeo, and had the wing on the boot, mean't it's AOA is optimised for slightly downward flowing air coming down off the rear screen rake and you'll notice the centre section has less camber compared to the ends (which are further away from the cabin and hence seeing more horizontal airflow. In my case, it's high enough to get air pretty much from a straight forwards direction, so it won't be drag optimised. However, the BTCC mondeo had around 310bhp, and would run to over 150mph. My car has 627bhp and runs out of gears at 121mph so i don't think a bit of drag is going to be an issue........ ;-)
Edited by anonymous-user on Friday 10th October 22:06
PhillipM said:
That's still waaaay more camber than my rear wing, which makes me wonder how much more I could get away with...
Stick some wool tufts to the underside, strategically place a GoPro to look at those tufts and take it for a drive. Increase AOA until tufts droop away from underside showing the boundary layer has become disconnected!(Even better, perforate the underside and use a fan to actively remove the boundary layer....... ;-)
CamMoreRon said:
Max_Torque said:
Remember this is a "Low speed wing" not an F1 car wing or aeroplane wing! It needs to work between around 50mph and 120 mph max. That means a deep chord with high curvature. Your typical wing you see people put on race cars often look like it's come off a Boeing and works well at around 200mph with a commensurately good L/D ratio, but the only downforce it provides in the real world is the weight of the wing itself....... It's also worth noting that the wing i have from the Mondeo BTCC is a combined wing anf gurney flap. It's difficult to tell from the pics, but it has a relatively shallow camber on the underside, and the large rear vertical section is designed to effectively "stall" the top side.
Of course, it was designed with CFD and optimised in a wind tunnel for the BTCC car, which as it was a mondeo, and had the wing on the boot, mean't it's AOA is optimised for slightly downward flowing air coming down off the rear screen rake and you'll notice the centre section has less camber compared to the ends (which are further away from the cabin and hence seeing more horizontal airflow. In my case, it's high enough to get air pretty much from a straight forwards direction, so it won't be drag optimised. However, the BTCC mondeo had around 310bhp, and would run to over 150mph. My car has 627bhp and runs out of gears at 121mph so i don't think a bit of drag is going to be an issue........ ;-)
Great reply, thanks. Of course, it was designed with CFD and optimised in a wind tunnel for the BTCC car, which as it was a mondeo, and had the wing on the boot, mean't it's AOA is optimised for slightly downward flowing air coming down off the rear screen rake and you'll notice the centre section has less camber compared to the ends (which are further away from the cabin and hence seeing more horizontal airflow. In my case, it's high enough to get air pretty much from a straight forwards direction, so it won't be drag optimised. However, the BTCC mondeo had around 310bhp, and would run to over 150mph. My car has 627bhp and runs out of gears at 121mph so i don't think a bit of drag is going to be an issue........ ;-)
Yeah I see what you mean now you've explained.. I think it was this photo that got me worried, as it just looks like a brick wall the whole way across!
But I found a good pic on t'internet (below) that shows the profile isn't that extreme, especially at the centre, and the sort-of gurney flap towards the sides.
Do your reg's say anything about wing height, or can you basically stick it up as high as you like?
Some quite good info here, but it's for aeroplanes, so you need to turn your screen upside down to view it in terms of "downforce"!
Highlift wings
(and worth remembering, that even at whilst flying "slowly" at landing, a typical airliners doing around 160mph!
There is also some interesting lift & drag data here:
Reverie CF wing sections
for a relatively deep section wing, showing L/Ds between around 13 and 8 for AOAs between 4 and 18 deg respectively.
Reverie CF wing sections
for a relatively deep section wing, showing L/Ds between around 13 and 8 for AOAs between 4 and 18 deg respectively.
AER said:
Given that the end of the car transitions into two huge vortices, I suspect a flat/horizontal wing is faaar from optimum. I'd bet it's also waaay different from the Mondeo to the point that the Mondeo wing is pointless.
I'd put some bits of string on the end of protruding poles stuck to the window approximately the distance the wing might be and then go video tape the results at various speeds to get a rough idea of what the air is actually doing and how you're going to get some downforce out of it without massive drag.
Of course, if it's just for the Halfords competition, then it's looking great!
You are not wrong my erstwhile antipodean ex-colleague! I've made the end plates large enough to hold pretty much any sensible wing section, and those sections will be adjustable for AOA, so as you mention, i can do a little bit of optimisation. The ex BTCC wing is ok for now, i'm damm sure it's not optimum, but i've got no race/championship to win, so to be frank, it's probably 75% "pub ammo" as you point out...... ;-)I'd put some bits of string on the end of protruding poles stuck to the window approximately the distance the wing might be and then go video tape the results at various speeds to get a rough idea of what the air is actually doing and how you're going to get some downforce out of it without massive drag.
Of course, if it's just for the Halfords competition, then it's looking great!
jebus said:
There are not words in English to describe the epic nature of this build, the attention to detail on the mechanical side of it is breathtaking, and could put even the most expensive super cars look thrown together. But bloody hell you are good with the electrical side of things, I think most of us on here would have set fire to the car, cubed it set fire to it again and been locked into a small padded room attempting even the early stages,
Can't wait to see video of this being used in anger.
^^Thanks, i try my best! ;-)Can't wait to see video of this being used in anger.
After what feels to be like days of sanding, filling, priming, more sanding, polishing etc i have nearly finished the patterns for the wing end plates:
End plate on the right just waiting for it's final polish, plate on the left still in un-sanded high gloss.
Also patterns for my carbon "smart" steering wheel and a new dash insert piece that will house the master WARN/caution controller:
More sanding/finishing tomorrow..............
End plate on the right just waiting for it's final polish, plate on the left still in un-sanded high gloss.
Also patterns for my carbon "smart" steering wheel and a new dash insert piece that will house the master WARN/caution controller:
More sanding/finishing tomorrow..............
The usual Polyester Resin. First coats are in the soft high build primer / tooling stuff (grey) the last coats in the much harder high gloss finish stuff. Annoyingly, these end plates are just too small / too intricate to really let rip with mechanical sanding methods (DA sander etc), doing big body panels is actually easier as they have much bigger radii and have more middle and less fiddly edges etc!
This week i have mostly been:
Covered in fibreglass and resin!
Next step in the wing end plate saga is production of the moulds, taken off the finished and polished patterns / bucks:
Due to the complex shape, it needs a 3 part mould with careful consideration of the split lines:
Basic wooden jig to hold material to form nice big split lines:
Nice thick gel coat layer covered by fine fibreglass tissue to support it.
4 layers of chopped strand mat, and a finishing layer of tissue (to avoid too many spikey sticky out bits that take lots of finishing to remove and stab/cut you to pieces when using the moulds!)
Finished 3 parts and also one half of the steering wheel mould as bonus extra ;-)
Due to it's complexity and requirement for significant strength, the steering wheel will be woven carbon fibre vacuum infused with Epoxy resin, whereas i will probably just wet lay up basic fibreglass / polyester resin parts for the wing end plates, at least for the first run to see how they come out
Also, in other less smelly/sticky news, Speedy Cables have extended my handbrake cable, originally from a V8 Vantage (long story) and changed the end fitting so i can mate it too my Skoda octavia handbrake lever:
Lever is tucked down the left hand (sill) side of the drivers seat, so i now have a nice MOT legal handbrake system! There is a much-more-useful-for-turning-around hydraulic flyoff handbrake lever on the centre console, but that isn't road legal, and it's going to get replaced by a virtual "handbrake simulator" in the ABS system i'm developing for the car anyway ;-)
Covered in fibreglass and resin!
Next step in the wing end plate saga is production of the moulds, taken off the finished and polished patterns / bucks:
Due to the complex shape, it needs a 3 part mould with careful consideration of the split lines:
Basic wooden jig to hold material to form nice big split lines:
Nice thick gel coat layer covered by fine fibreglass tissue to support it.
4 layers of chopped strand mat, and a finishing layer of tissue (to avoid too many spikey sticky out bits that take lots of finishing to remove and stab/cut you to pieces when using the moulds!)
Finished 3 parts and also one half of the steering wheel mould as bonus extra ;-)
Due to it's complexity and requirement for significant strength, the steering wheel will be woven carbon fibre vacuum infused with Epoxy resin, whereas i will probably just wet lay up basic fibreglass / polyester resin parts for the wing end plates, at least for the first run to see how they come out
Also, in other less smelly/sticky news, Speedy Cables have extended my handbrake cable, originally from a V8 Vantage (long story) and changed the end fitting so i can mate it too my Skoda octavia handbrake lever:
Lever is tucked down the left hand (sill) side of the drivers seat, so i now have a nice MOT legal handbrake system! There is a much-more-useful-for-turning-around hydraulic flyoff handbrake lever on the centre console, but that isn't road legal, and it's going to get replaced by a virtual "handbrake simulator" in the ABS system i'm developing for the car anyway ;-)
young man? if only eh! ;-)
This composites business is a total time sink to do properly though, especially with small fiddly bits like this where you can really apply significant mechanical sanding / finishing etc. By comparison, the massive moulds i made for the wings, bonnet and roof were a doddle..........
This composites business is a total time sink to do properly though, especially with small fiddly bits like this where you can really apply significant mechanical sanding / finishing etc. By comparison, the massive moulds i made for the wings, bonnet and roof were a doddle..........
rhinochopig said:
MT is there any FEA or similar for the steering wheel? The only reason I ask is that I would worry about it failing catastrophically if I'd built such a thing myself.
No. FEA for composites is a total nightmare tbh! (as you don't really have a homogeneous material...I shall be doing the following:
1) putting in loads of carbon fibre (i don't really care if it's 0.5kg too heavy etc
2) Using an internal kevlar layer to resist crack propigation and sudden catastrophic failures
3) Making the first one, bolting it to a "fake" steering column, and carrying out some basic torque and load tests to see where it breaks!
In reality, the handwheel loads in a car with PAS are quite low, and with a full race seat and harness, it shouldn't need to cope with being used as a "driver steady/restraint" during vigorous cornering etc......
shoehorn said:
Max are your various electronic modules interconnected on some sort of can/van/lin system or apart from stuff like engine/TC/LC, are they all independent of each other?
All modules are on a CAN bus, well actually two. There is the "body" bus, which has basic vehicle system duties, like switching on lights, wipers etc and the "powertrain" bus which has all the important things like EMS, Throttle, Transmission, ABS controllers etc on itshoehorn said:
One more question,why the choice of engine?
As AER says, it was kinda a left over from an earlier project ;-)Munter said:
chuntington101 said:
I think Max should get a blog going. Either telling us what he is doing on the car or at work.
We wont tell anyone.
We wont tell anyone.
If he tells us what he's doing at work...I suspect he'll have more time to spend developing the Ibiza.Win:Win
Gassing Station | Readers' Cars | Top of Page | What's New | My Stuff