Dale
|
| posted on 9/4/07 at 01:33 AM |
|
|
Downforce ???
I have been trying to sort out a way of not lifting the front of the car off the gound at speed with the fenders I have been working on. Other than
wrapping the front of the suspension around like the morgan I was wondering if going this route would vent out the air trapped between the wheel and
engine compartment/nose. Basically just an air dam behind the front wheel. I think the norm would be to vent it to the side behind the wheel but I
dont want a big opening there .
Dale
 
Rescued attachment DSCF0002_resize.JPG
Thanks
Dale
my 14 and11 year old boys 22
and 19 now want to drive but have to be 25 before insurance will allow. Finally on the road
|
|
|
|
|
Dale
|
| posted on 9/4/07 at 01:34 AM |
|
|
also
 
Rescued attachment DSCF0005_resize.JPG
Thanks
Dale
my 14 and11 year old boys 22
and 19 now want to drive but have to be 25 before insurance will allow. Finally on the road
|
|
|
ghuncha
|
| posted on 9/4/07 at 05:53 AM |
|
|
well don't know about aerodynamics but from what is visible in the pics, i don't think that the wheels will turn... right....
|
|
|
caber
|
| posted on 9/4/07 at 07:06 AM |
|
|
I think that will work to prevent uplift but not provide downforce as such. You might try and design the suspension shroud to have a longer surface on
the underside to make a bit of an aerofoil however it probably won't give negative lift if there is a lot of air coming through the wheel arch
however if you keep the front edge of the arch close to the ground and curve it outwards you shouldn't get too much air under there.
If you look at a lot of sports racers in the early 70s they had small spoilers wrapped around the edges at the front, look at Porches 907 to 917 or
the Lotus 47 racer to see what I mean. They might also have appeared on the Chaparal 2C or 2D at some point, they were the leaders in Downforce
aerodynamics after all!
Caber
|
|
|
Mr Whippy
|
| posted on 9/4/07 at 07:06 AM |
|
|
Yeah that looks fine, like I said before, you really don't want the air getting under the wings like my Falcon does.
Have you tried turning the wheels yet? As you might find the arch a bit tight especially on full suspension compression. Why not jack the front up and
remove the coil over too check.
Fame is when your old car is plastered all over the internet
|
|
|
worX
|
| posted on 9/4/07 at 11:00 AM |
|
|
The forward sloping dam that you have designed isn't necessarily the best shape (I think). The reason being that you also have to consider fully
the shape after the forward slope body panels.
If you think of a scalloped aeroplane wing you will get a better idea of what I mean.
Obviously the tear drop shape leading to a convex curved surface area on the TOP of the wing will generate LIFT, but the teardrop shape (a shape
opposite to your dam) leading to a concave curved surface shape on the BOTTOM, will generate NEGATIVE LIFT.
Which is what you need I think. (and it's a big I THINK, as I have only picked these things up whilst talking to historic racers about
they're body panels!).
I hope this makes sense to you, and I wish I could draw it on something to explain it better as that would be a lot easier, but I can't!
All the best, and I am really liking the mods you have made so far by the way...
cheers,
Steve.
|
|
|
britishtrident
|
| posted on 9/4/07 at 11:30 AM |
|
|
Never mind lift it would create so much drag you would need about 500bhp before lift became an issue
|
|
|
907
|
| posted on 9/4/07 at 12:39 PM |
|
|
I'm watching your progress with a great deal of interest Dale.
It'll turn out fantastic I'm sure.
Paul G
|
|
|
MustangSix
|
| posted on 9/4/07 at 12:39 PM |
|
|
A spoiler or wing behind the front suspension will be a lot less effective due to the turbulence of the air going over it.
Your design will probably be a lot slicker with less lift if you continue the Aero8 cues by pulling the entire front end together as an air dam to
reduce airflow under the car.
|
|
|
Dale
|
| posted on 9/4/07 at 01:02 PM |
|
|
As it sits I cant turn the wheels so I need to open up the arch a bit more to get clearance. I will probably go with a air dam/spoiler on the front
bottom like the aero 8 if for no other reason than I will need a support for the front of the fender / wing.
I guess I am not really looking to add more downforce to the car but vent the air trapped between the nose and wheel without causing more lift. The
air dam behind the wheel can be curved more to the bottom of the chassis around the radius that the wheel has to turn which might help some.
Thanks
Dale
Thanks
Dale
my 14 and11 year old boys 22
and 19 now want to drive but have to be 25 before insurance will allow. Finally on the road
|
|
|
Rob Palin
|
| posted on 9/4/07 at 05:20 PM |
|
|
As long as there's a large radius at the top of that slope, where it blends into the upper surface of the bodywork (R~120mm) then it should only
be a good thing. The radius is to ensure that any air flowing up that slope has a chance to make the turn at the top and stay attached to the upper
bodywork.
If the top corner is too tight then the flow will separate and you'll have a kind of jet exiting from the wheel-well / engine bay area which
won't be good for drag - and it will leave that region highly susceptible to collecting dirt and muck.
|
|
|
Dale
|
| posted on 9/4/07 at 06:45 PM |
|
|
-------------------------As long as there's a large radius at the top of that slope, where it blends into the upper surface of the bodywork
(R~120mm) then it should only be a good thing. The radius is to ensure that any air flowing up that slope has a chance to make the turn at the top and
stay attached to the upper bodywork. ----------------
I have heard conflicting things to do there-I understand what you are say there will reduce drag but will it also negate any down pressure that
pushing the air up would have created. putting a large radius on the top of it will give it a high degree of lift. I supose that it may be better
to get the drag down at that point more than decreasing lift. Some down force could be aplied at the very front in the support for the front of the
fenders.
Dale
Thanks
Dale
my 14 and11 year old boys 22
and 19 now want to drive but have to be 25 before insurance will allow. Finally on the road
|
|
|
Rob Palin
|
| posted on 9/4/07 at 07:56 PM |
|
|
That's not necessarily the case. There would be three competing mechanisms at work; channelling the air upward would generate some downforce
and then turning it horizontal again would generate some lift. Povided both direction changes are done 'smoothly', the net momentum
change of the air is very small, and will be felt by the car largely as drag.
You could use that part of the body for 'pure' downforce generation, however, by fitting a small splitter at the bottom edge or radiussing
it fairly tightly - if you've got a reasonably smooth underfloor.
|
|
|
