tom_loughlin
|
| posted on 11/1/07 at 06:26 PM |
|
|
I did my 60k word dissertation o this very topic - i found the biggest factor was the outboard wheels - by enclosing them, you can cut Cd by approx
25%. other mods, diffusers, spoilers, aeroscreens, flat bottoms, rear end breakaway, wakes atc...were looked at too....pretty interesting stuff if
you're a geek like me!
Tom
|
|
|
|
|
chriscook
|
| posted on 11/1/07 at 06:35 PM |
|
|
Rob - Thought you were busy working to make someone else's race car better...
[Edited on 11/1/07 by chriscook]
|
|
|
Rob Palin
|
| posted on 11/1/07 at 06:40 PM |
|
|
Yes, i am, but currently the computer's doing all the hard work and i'm just waiting for it to finish. Tick tock, tick tock...
|
|
|
Volvorsport
|
| posted on 11/1/07 at 07:00 PM |
|
|
dont forget skin friction , all ferraris are painted red because the paint is smoother
the body is so bluff that to do it right would involve a full body, thats why im doing it - i need to reach 200mph.
www.dbsmotorsport.co.uk
getting dirty under a bus
|
|
|
jack trolley
|
| posted on 11/1/07 at 07:20 PM |
|
|
Is the 'MK inboard' top wishbone bent or "pre-failed" as The Blessed Colin
would say? 
|
|
|
JoelP
|
| posted on 11/1/07 at 09:23 PM |
|
|
bent but no a big deal IMHO, it doesnt see as much force as the lower one, mainly braking etc. Plus theres always the argument that you want the bones
to bend before the chassis!
|
|
|
procomp
|
| posted on 11/1/07 at 10:23 PM |
|
|
Hi having built the first westfield with the full body kit on i can tell you for definate it take 10 mph of your top end at 135 mph .
[img]http://www.locostbuilder.co.uk [/img]
cheers matt
|
|
|
Middy Tim
|
| posted on 11/1/07 at 11:07 PM |
|
|
quote:
Originally posted by DarrenW
Wouldnt it be easier to compensate for the poor aerodynamics with a bit more power?
I wouldn't worry about more power. A 225+ bhp SR20 is in the plans... and that's the stock engine.
|
|
|
Rob Palin
|
| posted on 12/1/07 at 09:22 AM |
|
|
Worth pointing out though that the power requirement for a given (high) speed increases by the cube of the speed.
If you want to go 10% faster you need 33% more power, then 33% more cooling which means even more drag and probably a reduction in that
10%benefit...
OR you could just reduce your drag in the first place. 
|
|
|
DarrenW
|
| posted on 12/1/07 at 09:30 AM |
|
|
If i was after good aerodynamics i wouldnt have even given a sevenesque a second glance. For me thats not what these cars are about. i can see why
someone might want a few % edge on the next man on a track but for most people its just down to the look you want and adding a little driver
comfort.
At the end of the day they are what they are - a quirky fun 60's styled sports car. Discussing how to make them aerodynamic is a bit like
discussing how to make a Pinto weigh 50Kg less - a waste of time.
|
|
|
iank
|
| posted on 12/1/07 at 09:53 AM |
|
|
quote:
Originally posted by DarrenW
... discussing how to make a Pinto weigh 50Kg less
Cast a new block and head in aluminium?  But it wouldn't be a pinto any more and still not as good as many more modern engine, which kind of
agrees with you point.
|
|
|
macnab
|
| posted on 12/1/07 at 10:23 AM |
|
|
quote:
Originally posted by DarrenW
If i was after good aerodynamics i wouldnt have even given a sevenesque a second glance. For me thats not what these cars are about. i can see why
someone might want a few % edge on the next man on a track but for most people its just down to the look you want and adding a little driver
comfort.
At the end of the day they are what they are - a quirky fun 60's styled sports car. Discussing how to make them aerodynamic is a bit like
discussing how to make a Pinto weigh 50Kg less - a waste of time.
quite right.
|
|
|
Rob Palin
|
| posted on 12/1/07 at 10:52 AM |
|
|
I take your point, but also people spend a lot of time & effort making the cars lighter to improve handling and performance - both of which are
also improved by aerodynamics.
Is it any coincidence that Colin Chapman's motto was "add lightness" but he was also one of the great aerodynamic innovators in F1?
|
|
|
Volvorsport
|
| posted on 12/1/07 at 10:00 PM |
|
|
aerodynamic forces increase by the square of the speed - indicated by the term V squared in the equation for drag force .
www.dbsmotorsport.co.uk
getting dirty under a bus
|
|
|
chriscook
|
| posted on 13/1/07 at 10:20 AM |
|
|
If you are referring to Rob's: "Worth pointing out though that the power requirement for a given (high) speed increases by the cube of the
speed."
Notice he says power not force. Cue power vs torque debate
quote:
Originally posted by Volvorsport
aerodynamic forces increase by the square of the speed - indicated by the term V squared in the equation for drag force .
|
|
|
Volvorsport
|
| posted on 13/1/07 at 11:50 AM |
|
|
if the aerodynamic force raises by the square of the speed then so does the power requirement to overcome them .
im sure if you did the maths you would realise that most cars would need quite a large amount of power just to get to 100mph .
www.dbsmotorsport.co.uk
getting dirty under a bus
|
|
|
Rob Palin
|
| posted on 13/1/07 at 11:55 AM |
|
|
Ta for the help Chris.
Volvosport - Aerodynamics is my day job so i do actually do that maths on a regular basis. Well, kind of, a while back i wrote a little macro for
Excel to do it for me.
Power = force x speed
and the drag force = 1/2 x density x speed squared x drag coefficient x frontal area
So Power ~ speed^3
Solving a cubic equation isn't that simple and an iterative approach is the easiest way, hence the macro. It takes in engine power, CD, frontal
area, mass, and drivetrain efficiency and allows you to calculate an estimate of your top speed OR to put in a target speed and then work backwards to
calculate either the CD or power required to achieve that, whichever one you don't already know.
[Edited on 13/1/07 by Rob Palin]
|
|
|
chriscook
|
| posted on 13/1/07 at 12:14 PM |
|
|
quote:
Originally posted by Rob Palin
Ta for the help Chris.
[Edited on 13/1/07 by Rob Palin]
I know you don't need it but thought it might be a while before you were back!
|
|
|
Rob Palin
|
| posted on 13/1/07 at 12:47 PM |
|
|
Yeah, am back into work shortly. Would have been there already but the garden fence has blown over and i've been sorting that out.
With the work thing i have to report my progress back to TD at the autosport show tomorrow. Late one tonight then...
|
|
|
Volvorsport
|
| posted on 13/1/07 at 06:57 PM |
|
|
yes and perhaps i should stop talking nutsack . i should know better having studied it properly too .
its always easy to say somert without thinking . im sure theres a thread somewhere where i agreed in the first place .
www.dbsmotorsport.co.uk
getting dirty under a bus
|
|
|
westcost1
|
| posted on 31/1/07 at 11:22 AM |
|
|
this one cool
 
Rescued attachment e2_1.jpg
|
|
|
westcost1
|
| posted on 31/1/07 at 11:23 AM |
|
|
and the back with wide arches
 
Rescued attachment e3_1.jpg
|
|
|
procomp
|
| posted on 31/1/07 at 03:24 PM |
|
|
Hi from actual testing i will confirm that that rear wing dose nothing but take top speed of the car.
At 130 mph it reduced the mph by as much as 5 mph using 200 bhp to drive the car.
cheers matt
|
|
|
jack trolley
|
 posted on 31/1/07 at 05:52 PM |
|
|
Interesting...
|
|
|
gazza285
|
| posted on 1/2/07 at 06:35 AM |
|
|
Ugly stick.
DO NOT PUT ON KNOB OR BOLLOCKS!
|
|
|
