How much downforce does the spoiler generate?
Discussion
Idunno.
But what I do know is that I noticed that my lurvly concentric tailpipes and grille holes have suddenly gone askew.
See here:
On further examination I found this:
and on the other side, this:
Now as far as I know the rear clip has never been allowed to swing open without a controlling hand and other than the spoiler downforce, there have never been any weight put on the tail.
Now I'll happily be proven a pratt if I've used the wrong washers from the kit. But I've not seen any larger ones.
Anyone else had this?
Once again, I post this purely to advise you all of a potential weakness which could give a nasty surprise if it suddenly gave way.
Now come on, tell me I've gotten the wrong washers in!!
Pete
But what I do know is that I noticed that my lurvly concentric tailpipes and grille holes have suddenly gone askew.
See here:
On further examination I found this:
and on the other side, this:
Now as far as I know the rear clip has never been allowed to swing open without a controlling hand and other than the spoiler downforce, there have never been any weight put on the tail.
Now I'll happily be proven a pratt if I've used the wrong washers from the kit. But I've not seen any larger ones.
Anyone else had this?
Once again, I post this purely to advise you all of a potential weakness which could give a nasty surprise if it suddenly gave way.
Now come on, tell me I've gotten the wrong washers in!!
Pete
I have no idea what those bolts are connected to, but is it possible that they're seeing aerodynamic loads from either the rear wing or the rear body shell? Both could be immense at high speed, especially worrying if the attachment point is starting to fail.
Edited by GreenV8S on Thursday 23 October 21:34
bluesatin said:
How strange. I have taken the Ultima to Bruntingthorpe numerous times and must have done over 50 runs at over 160mph on a very bumpy surface and the mounts are fine!
What upper flap setting do you use though? I normally do my high speed runs without the flap. But on recent trackday outtings the flap has been on 3/4s attack mode.The factory say that the flap makes a huge difference.
Have you spoken to the factory about it?
I'd say you use your car as it's "intended" more than anyone else, so if you've discovered a weak point, it's perhaps something the factory could comment on? Do they have any demonstrators (do they keep them long enough?) that have done as many high speed runs and track days as you?
What sort of speed is it providing enough downforce so on high speed corners it's not just exerting force straight down, but also to the side to a degree?
I'd say you use your car as it's "intended" more than anyone else, so if you've discovered a weak point, it's perhaps something the factory could comment on? Do they have any demonstrators (do they keep them long enough?) that have done as many high speed runs and track days as you?
What sort of speed is it providing enough downforce so on high speed corners it's not just exerting force straight down, but also to the side to a degree?
To be honest, apart from the expense and that IMO the Can-Am can get away with not having a wing, the thing that puts me off getting one is that the bodywork is being subjected to the downforce and not, as in the Sport, the chassis directly.
I stand to be corrected but would it not be better to somehow mount the wing so that most of the force is on the chassis?
I stand to be corrected but would it not be better to somehow mount the wing so that most of the force is on the chassis?
Graham-P said:
To be honest, apart from the expense and that IMO the Can-Am can get away with not having a wing, the thing that puts me off getting one is that the bodywork is being subjected to the downforce and not, as in the Sport, the chassis directly.
I stand to be corrected but would it not be better to somehow mount the wing so that most of the force is on the chassis?
I had a lengthy debate with Wayne about this as it was a concern that he had. The spoiler is bolted THROUGH the body, but the force is transfered through the aluminium triangulated supports which are then mounted to the box sections that are glassed into the body and the hinge points. The force is effectively transferred directly to the rose joints which are boted at 90 degrees into the slots. The further the rose joints are out from the slots the greater the turning moment and as you can see, with a washer that small, all the force is transferred to the lower edge of the washer which digs in to the marterial to the narrower, outside strip of metal.I stand to be corrected but would it not be better to somehow mount the wing so that most of the force is on the chassis?
I will have to weld, and then plate. Perhaps making a hole in the plate rather than a slot as my rose joint position is now determined.
I'll call the factory to see if they can think of a better way.
Laters
PEte
Interesting!, is the mounting on the GTR different than the Canam, or has it been changed. On the Canam the fixing bolt goes into a captive nut bonded to the body rather than a slot.
Certainly noticed how much difference the wing angle made on recent long journey to Dijon. Dropping angle as close to zero as possible certainly reduced drag and incresed fuel efficiency on long cruise.
I have also noted that the triangular brackets supporting the wing in engine bay have fatigued over time and have already replaced one. Check carefully!
Certainly noticed how much difference the wing angle made on recent long journey to Dijon. Dropping angle as close to zero as possible certainly reduced drag and incresed fuel efficiency on long cruise.
I have also noted that the triangular brackets supporting the wing in engine bay have fatigued over time and have already replaced one. Check carefully!
I have a couple of spare uprated support brackets I made from thick ali if anyone is interested... I thought that this was a weak area, hence I made my own uprated brackets. PM me if interested.
I am also making an adjustable angle bracket that fits behind the plate to help spread the load into the chassis. I will post some pics when completed.
Cheers,
Mart
I am also making an adjustable angle bracket that fits behind the plate to help spread the load into the chassis. I will post some pics when completed.
Cheers,
Mart
I e-mailed my friend Simon McBeath, who, amongst other things, design wings and aero packages for a living. This is what he said :-
"Hi Kelvin
Take a look at http://www.sm-designs.co.uk/aerofoildata.htm
for some wing data (and feel free to point folk to this if you post something on that web site). You can work out from those numbers how much downforce dual element wings make (NB the data were on wings in freestream so they won't make that much on the back of a car, but the graphs are a guide to the scale of the forces).
From these plots I reckon that for a wing to make 1000kg of downforce requires a speed of 230 to 240mph...
Vibrations + high loadings can wreak havoc.
Poorly designed wing mountings are very unsafe.
Aerodynamic devices are a safety related items and require the requisite great care during manufacture and installation"
Just some info for those who are interested.
Regards
Kelvin
"Hi Kelvin
Take a look at http://www.sm-designs.co.uk/aerofoildata.htm
for some wing data (and feel free to point folk to this if you post something on that web site). You can work out from those numbers how much downforce dual element wings make (NB the data were on wings in freestream so they won't make that much on the back of a car, but the graphs are a guide to the scale of the forces).
From these plots I reckon that for a wing to make 1000kg of downforce requires a speed of 230 to 240mph...
Vibrations + high loadings can wreak havoc.
Poorly designed wing mountings are very unsafe.
Aerodynamic devices are a safety related items and require the requisite great care during manufacture and installation"
Just some info for those who are interested.
Regards
Kelvin
Luvky,
My flaps are flat!
I have noticed that on more modern Ultma the upper wing goes a lot flatter!
Manages to hold on ok in this!
http://www.pistonheads.tv/clip313
My flaps are flat!
I have noticed that on more modern Ultma the upper wing goes a lot flatter!
Manages to hold on ok in this!
http://www.pistonheads.tv/clip313
Spoke to the Factory.
No known issue and they've checked their demos which have done high speed runs with dual planes.
They agreed that a weld fix would do the job and thought a bigger OD washer would help spread the load in my case.
Ted explained the load paths from wing through to rose joints, just as I had explained before - so please guys, take this as an example of how the the spoiler DOES transfer the load to the chassis - not into the body!!
Now...I wonder if Adrian knows how to handle welding equipment???
Lucks out.
No known issue and they've checked their demos which have done high speed runs with dual planes.
They agreed that a weld fix would do the job and thought a bigger OD washer would help spread the load in my case.
Ted explained the load paths from wing through to rose joints, just as I had explained before - so please guys, take this as an example of how the the spoiler DOES transfer the load to the chassis - not into the body!!
Now...I wonder if Adrian knows how to handle welding equipment???
Lucks out.
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