Is the HAH spoiler functional or decorative?

Alan

 

Hi AlanWBaker;
This is nothing more than just my (Opinion) but I have over the yrs. owned alot of extremely fast cars like the M Series BMW's, AMG Mercedes, Turbo 911 & 930 Turbo Porsche's, Z06 Vettes, SS Camaro's, Saleen Supercharged Mustangs, Audi Turbo S4 and I think you get the idea, Right? To the point, if a person is not driving probably over say 130MPH plus I really doubt that a rear spoiler on anything truly makes a difference. As you know they are suppose to add down-force and keep the rear end pushed down on it's suspension to not let the car wonder around on the road, so if your not driving at really fast speeds and I don't see how anyone is going to be able to do that with traffic being the way it is today, a rear spoiler is (Probably) more for looks. (IMO)

Terry

BTW; Nothing wrong with that though, I like the way they look personally:

 

Could be there for aerodynamics rather than downforce like is needed on a race car. I have seen video of some wind tunnel testing on other cars (not the HAH) where they introduce a thin like of smoke into the wind path to see how the air flows smoothly over the shape of the vehicle. As I recall, there is ususlly some turbulance or "eddys" created just after the stream exites the surface of the rear of the vehicle, which I assume could be translated into "drag". Maybe the spoiler changes the direction of the air stream upward slghtly to make for a cleaner exit, less turbulence and therefore less drag. Just my theory, don't know if there is any truth in this. I do know that the Honda engineers worked there magic to get the drag coefficient down to .29, which included the design of the wheel spokes.

 

Kaymack- you correctly interpreted those videos. Eddies in the wake are caused by low pressure existing there...the eddies are air filling in that vacuum. An abrupt end (like a boxy trunk on a car) is a very good way to create a lot of drag. Smooth entries and smoother exits are what is necessary for low drag. Take a look at a racing sailboat hullform- smooth in, smooth out. The waterborne portion of the stern is NEVER squared off.

Our spoiler delays the onset of turbulent flow to be further away from the vehicle, nudging that airstream 'up and over' the sudden change, exactly as you guessed. This lessens the abruptness of the transition into the wake/low pressure behind the vehicle- spreads it out over a larger volume.

Think about trim tabs on a boat, and flip it around in your head- you can leave a really big hole in the water behind you to create a rooster tail and make it good for surfing, or you can make less of a hole, flatten the boat, ride smoother, and save fuel.

There were a few Navy ships fitted with fixed 'tabs' on the stern at the waterline, similarly to our spoiler. They actually angled down a few degrees (flip it in your head for our car picture), and did improve fuel consumption a few percent. It's real.

 

But truly, I think the spoiler is there as a place to nudge the trunk open with your hip. No grimy fingerprints on my car's backside, thank you very much

 

A spoiler on the rear of a front-wheel drive car that provides downforce on the rear of the car at speed is a pretty bad idea. That's because that would create less force downward on the drive wheels, where it is needed for performance driving. So feel free to laugh at all the big spoilers on FWD cars that are pretending to be there for extra performance. The majority of them are just there for looks, of course. The owners, however, generally don't know that, in theory at least, they have made things worse, not better. (Although tigerhonaker is also correct that at normal driving speeds, there is very little downforce effect).


In theory, the design of the lip spoiler on the HAH trunk improves aerodynamics by a slight amount, as others have said.

 

Well said guys in the case of the HAH & the HCH the rear spoilers are there to control Air-Flow over the rear of the vehicle to as you all have pointed out lower the drag.
I went the wrong way on this one and (Wrongly) was thinking the question was about the performance side and it is not. I'm to old and was thinking of very fast cars with rear spoilers to control lift and in this case wrong direction. "Sorry". Slap-Slap; Wake-Up

Terry