Body panel's vs Airflow

[deran4ecc]

I notice more single seater car's leaving most if not all of the rear body panels off. Does this actually help, as I would have thought smooth air flow around past the Engine plus other parts, would help with downforce and drag.
I really hope we don't start to see the same as some car's on the Australian hills.

[Darvie]

To clarify the Australian bit,you are possibly are refering to the car running in the youtube thread-huntley hillclimb-win tv, that car is the Hay Honda built by Ron Hay in the late 60s/early 70s powered by a supercharged Honda 6 cylinder bike engine.
Ron bought the car back a few years ago and rebuilt to original spec to run in historic hillclimb class and historic racing then the fun started,he was not allowed to body it as it never ran with one in its period also not allowed to run historic racing as it was only originally a hillclimb car.
We now run the Force without the engine cover because it now runs without the sidepods together with a Malcolm Oastler reworked floor so nothing to attach the panel too.
We would never consider taking anything off the Gould!.

[darcia1]

As i can only account for cars that run here in Victoria .... some of Brett Haywards early cars had no bodywork at all. Rod Moody Cheetah has historic f2 bodywork but in hillclimb guise has no rear bodywrk due to installaltion of SC toyota 4age...Foley Dallara now tub only w 1300 busa... Most cars here in Aus run w bodywork.. as Darvie has explained ..

[Clive Austin]

As with most things - it is a trade off. You are right re air flow. The longer it can stay attached and the less turbulent the less drag. The smoother the flow by the time it reaches the rear wing the better the wing will work - ie more downforce from the wing and the better the floor should work. However, at the sort of speeds (particularly corners - Prescott bridge excepted) we do there is a question as to how much this is all worth in practice. The aero isn't really doing anything below c60mph. On the flip side you have weight and drag. Many people running bile engines lose a lot of both by eliminating the side pods - there is enough room to repackage things like battery, rad, exhaust etc. If I didn't like the look of them I'd probably do this. As for engine cover, you would expect drag to increase quite a bit by removing this with all the "gubbins" exposed to the air flow so the call isn't as clear cut. For me I'd leave it in place unless is was made of lead!

I think there is a rule in the blue book preventing any further stripping. No doubt someone more familiar will be able to quote it.

There are a couple of good books. McBeath is a good entry point and Katz takes it to the next level. The key point though is that no book is going to let you nail your aero without access to a tunnel to tweak it. Both very interesting reads though.

C

[grahamb]

At what speeds do aerodynamic laws start to apply?
Ie are there some events where you would benefit from the weight loss rather than the lack of aero?

[Clive Austin]

Not much effect sub 60 Graham.

C

[SteveSlowboy]

I believe the engine cover is often removed (on bike engined single seaters) to aid cooling. At the detriment to airflow over the rear wing.

Steve

[asklepios]

My experiments,with an OMS suggested 1-2 mph faster down a long straight (Golspie in this case), with cover, but same times. I concluded that slippery with cover ,but as configured the wing worked better in low speed corners.
Perhaps the rough engine contours acted as vortex generators?
As for speed at which wings work,while the downforce increases with V squared , you will find many light aircraft take off at 40-45 kts,and are producing (lift) at 35-40, (I accept that aerofoils differ)

Anyone running without a wing in a single seater (where is Image?) will attest to the oddness of the effect

[Radical]

Originally Posted by asklepios

Anyone running without a wing in a single seater (where is Image?) will attest to the oddness of the effect

Yes, when I ran the Hawke I had the odd ( mainly hay bail induced) occasion to remove the front wing, and found the handling upset so then took of the rear which helped balance the car, albeit at lower over grip levels.

It is also worth pointing out the Hawke was a converted FF1600 so was never designed to have wings and the wins were both small and no doubt highly inefficient compare to modern hill climb wings.

[Alpinepg]

I think there is a rule in the blue book preventing any further stripping. No doubt someone more familiar will be able to quote it

I dont think such a rule exists - the Ghost single seater run by Jonathon Rarity (think thats his name....someone will be along shortly to correct me if its wrong!) that I saw in 2010 ran totally naked at several events....and set some class records in the 1600cc class.