AERODYNAMICS: Sedan vs Wagon vs Ute

[XW #901 180mph]

Does anyone know of any reasearch or magazine articles on comparisons of wind drag figures on sedans vs wagons vs utes.

It probably doesn't matter what type of car the info is on providing the 3 body shapes tested or compared were the same model and year as each other as it would really only be a comparison of how the air flows over and off of the rear of the car.

Any info would be appreciated.

Regards Mark.

[DON NOBLE ... DLRA # 281]

well i havent got any scientific evidence , but in my opinion in order of sliperyness i would say
1/wagon
2/sedan
3/ ute .
wagons generally have 1 sloping rear end area , and usually a less abrupt angle than a sedan or ute . maybe that helps . I have a wagon but not bcause it was more aerodynamic , ended up with it by default .

[hawkwind racing]

Mark generally speaking the best shape out of sedan/wagon/ute is in the following order
1.sedan 2. wagon 3. ute the best shape for a "normal" car is a hatch back ,if you are interested in drag reduction view the following site as it will whet your appitite to follow up on some more rigorous research
http://www.mitsubishi-motors.com/corpor ... 16E_03.pdf

Gary (hawkwind racing )

[Desert Rat Racing]

I agree with Don Noble, the wagaon would be better as there is only one area of resistance where the sedan has 2 the rear window then the boot lid area and the ute well unless you take the tailgate off altogether you have lots of bufferting I even think with the tailgate off there's still a fair amount, but with not having done any test and not having read all the website put up by the last respondant I couldn't say truthly what is the best there is a little say that goes something like this " suck it and see, if it works it works that's all that matters" I think it's a try it and see situation, so try it and see.

[garth04]

I don't know of, or have ever seen any airflow comparison tests between body styles, as most data is based on the mass produced item, ie sedan.

The most streamlined is obviously the best so the coupe / sedan rates first, not too many ferrari wagons or utes about.

Ute is next if it has a hard tourno cover, last with open tray.

Wagon would generally be last due to the great disadvantage having such a large flat rear area causing a tidal wave of air disturbance behind it.

[Dr Goggles]

...agree with the last post ...one of the most important things in aero-dynamics is leaving as little wake as possible or in other words "putting the air back together neatly" thus the wagon is going to give a fairly dramatic low-pressure zone trying to pull it backwards because of the sudden collapse of cross-sectional area at the tailgate. Another approach here is to imagine which car the manufacturer would like to have the best Cd ...it'd always be the sedan wouldn't it ? In that , if they spend any money on it that it will be on the fleet units .With deference to Don Noble , the Skyline sacrifices load space for a better rear angle so it's probably very similar to the same year sedan...it depends on model...........but I'd back sedans/coupes every time

[XW #901 180mph]

From the info that Hawkwind Racing posted from the Mitsubishi Aero testing I am now convinced to stay with the sedan body.

The main reason I had some reservations on which body shape was best is

A:
A few 2 Litre racing teams in the UK and Australia used Volvo wagons for a while in the mid 90's so I thought there may be a good reason for this.

I have tried running a 351 XW Wagon around Mallala and found that the 80kg extra over the back helped balance out the turn in of the wagon vs sedan due to the huge weight over the front wheels of the cleveland but overall lap times were around 1 second slower due to the extra weight.


B:
In my younger days we had a couple of open road trips (lets say in NT to keep things legal) and on one of the trips we were running XR - XY sedans with very equal std 4 barrel mannual 351's with 2.75:1 diffs and at around 130 to 135 mph (flat to the boards) we struggled to overtake each other.

On a later trip with drivetrains as above we were running XR to XY wagons under the same conditions and were able to slipstream and pass one another but the moment you were overtaken you picked up the other wagons slipstream and went straight past again.

This brought me to the conclusion that the wagon body was producing a huge hole in the air behind it which is maybe not a good thing.

Regards Mark.

PS: I dont drive like this anymore.

[momec]

G'Day
Utes Rule OK!!
If you study the shape of fish I think they are very efficient shapes. Water and air have a lot in common only water is harder to push through.
Almost all fish taper to the rear so there is virtually nothing in their wake,
the faster the fish, ie barracuda, they longer the taper. Some are almost blunt at the front and they still seem to work.
No fish look like utes.
Seeya Chris

[gazza414]

Thats one way of looking at it Chris---- thank goodness we can have alota different classes for fish too!!!! we should consult Darwin hey!!!

As far as a Ute is concerned for ultimate speed -- stick with Hawkwinds post.

[Dr Goggles]

Hey Gazza
The Darwin idea is a nice one but sadly I think there are too many rules (with safety in mind) for true natural selection to take place ...plus we'll need some heavy duty predators to take out the slow movers('cause they're never gonna hurt themselves)....as for random mutations...do I need to list 'em?.....Chris mentioned Fish ....I'm thinking of a certain lakester that would look right at home down in the deep where the light don't go....all that said I ain't never seen a rusty fish.

On a more serious note .The Mitsu post is a beauty , thorough and simple to understand .An aero engineer we spent time with tank-talking put it simply , "it's all a compromise and you need to decide what functions you need " he was explaining that we could get a super sleek Cd for our tank but it wouldn't help with directional stability , not relevant to many here .The VG use is an example of that compromise...so are wings , ducting (sort of)....what about sharkskin suits...........

[gazza414]

.. Good post Googles.

Its always a compromise, including access to the hip pocket. The gains at the top are very small. Aero is the way to think / move toward as power becomes a lost cause on the BIG WHITE DYNO.

Natural selection is at play on the salt too. I 've seen the Beagle floating around out there!!!! There are casualties in the scheme of events.

[Dr Goggles]

....yeah I saw the HMS Beagle and the HMS Bitsa and the HMS Mongrel ...I can't let the fish thing thing go though ......When will the flathead guys move onto land?...... are the guy's running snails on a different evolutionary path......
james

[gazza414]

We are hijacking this thread Googles.
I've seen a NOS Flathead out there a couple of years ago.... certainly not a bottom dweller, and then a few snails who have certainly jumped the evolutionary que and spin and blow hard.
My mates Hayabusa has such an evolutionary snail attached!!! They are called high boost scooters!!!!


NOW can someone contribute some aero dribble pls to this post...... thankyou in advance

[Norm]

Can anyone help me. We are looking at putting moon discs on the Gnome and are trying to work out do they realy work, how do they work and what possible benifits we will get.



Norman
Gnome Racing
SIX IN A ROW THE ONLY WAY TO GO

[DON NOBLE ... DLRA # 281]

Can anyone help me. We are looking at putting moon discs on the Gnome and are trying to work out do they realy work, how do they work and what possible benifits we will get.



Norman
Gnome Racing
SIX IN A ROW THE ONLY WAY TO GO

Well ive allways wondered if they did anything , dont know of any scientific tests that have been done . To me the side of the wheel is not facing the wind , and therefore not causing any resistance , i may be wrong . But i reckon they look good , BLING salt lake style , and its kind of tradition . So when you look in the shed and see the car with the moon discs on , thats the one you take to the salt lake .