Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post

aerohead · 05-03-2012, 06:53 PM

Some of the 1st-gen water-cooled VWs were of Hucho's design recommendations,per wind tunnel investigations at VWs climatic wind tunnel.
This was the time of the 1st Arab Oil Embargo and many 'economy cars' had underbodies more akin to today's body-on-frame pickups and SUVs.
Hucho published in 1976 with an SAE paper which included front airdam research.
At that time,for all the cars tested,a drag decrease of up to 15% was possible by utilizing only a front airdam.
From R.G.S.White's research at MIRA in the UK,it was understood that the 'better' a cars underside,the less effective an airdam would be.
FIAT has demonstrated that airdams can increase drag on 'low-drag' cars.
'Airdams' had entered the market in 1966 with GM's 'modesty panel' on their Corvair,after development at the GALCIT wind tunnel at CAL Tech under the direction of Dr.Peter Kyropolous.
In Hucho's 1976 paper they show results from 12-airdam combinations of 4-different configurations on the sloping valance panel of a VW do Brasil 1600X.
The highest drag occured on the vertical dam closest to the front wheels at a depth of 60mm.
A 180mm,45-degree dam (ala Dodge Daytona ) showed no drag reduction at all.
The lowest drag came from a 40mm vertical dam halfway upstream towards the base of the angled dam.
-------------------------------------------------------------------------
Attaching the 'optimum' nose netted a 0.05 drop in Cd.By softening the hard edges slightly they were able to come within 5-points of the 'optimum'.
-------------------------------------------------------------------------
The nose of a 1976 Golf/Rabbit is within 5-points of 'ideal,'as far as zero-yaw is concerned.
This is the reason he basically recommends we blow off the front of the car as far as mods go,and just concentrate on the back.
The lowest cost entry level economy car sold today is a quantum leap,aerodynamically,from similar class vehicles of the first 'oil crisis.'
And there is a very good likelihood that whatever airdam comes from the factory on a new car,has already spent a number of hours of refinement in the tunnel or inside a $billion,neural-net, 3-D, Navier-Stokes CFD program.

05-03-2012, 06:53 PM	#19 (permalink)
aerohead Master EcoModder Join Date: Jan 2008 Location: Sanger,Texas,U.S.A. Posts: 16,164 Thanks: 24,305 Thanked 7,327 Times in 4,734 Posts	Science Some of the 1st-gen water-cooled VWs were of Hucho's design recommendations,per wind tunnel investigations at VWs climatic wind tunnel. This was the time of the 1st Arab Oil Embargo and many 'economy cars' had underbodies more akin to today's body-on-frame pickups and SUVs. Hucho published in 1976 with an SAE paper which included front airdam research. At that time,for all the cars tested,a drag decrease of up to 15% was possible by utilizing only a front airdam. From R.G.S.White's research at MIRA in the UK,it was understood that the 'better' a cars underside,the less effective an airdam would be. FIAT has demonstrated that airdams can increase drag on 'low-drag' cars. 'Airdams' had entered the market in 1966 with GM's 'modesty panel' on their Corvair,after development at the GALCIT wind tunnel at CAL Tech under the direction of Dr.Peter Kyropolous. In Hucho's 1976 paper they show results from 12-airdam combinations of 4-different configurations on the sloping valance panel of a VW do Brasil 1600X. The highest drag occured on the vertical dam closest to the front wheels at a depth of 60mm. A 180mm,45-degree dam (ala Dodge Daytona ) showed no drag reduction at all. The lowest drag came from a 40mm vertical dam halfway upstream towards the base of the angled dam. ------------------------------------------------------------------------- Attaching the 'optimum' nose netted a 0.05 drop in Cd.By softening the hard edges slightly they were able to come within 5-points of the 'optimum'. ------------------------------------------------------------------------- The nose of a 1976 Golf/Rabbit is within 5-points of 'ideal,'as far as zero-yaw is concerned. This is the reason he basically recommends we blow off the front of the car as far as mods go,and just concentrate on the back. The lowest cost entry level economy car sold today is a quantum leap,aerodynamically,from similar class vehicles of the first 'oil crisis.' And there is a very good likelihood that whatever airdam comes from the factory on a new car,has already spent a number of hours of refinement in the tunnel or inside a $billion,neural-net, 3-D, Navier-Stokes CFD program.