And now...Deep Thoughts on the OEM Rear Wing.

Is it me or does this rear wing remind you of....


A Klingon Bat'leth?

 

You can rip it off the car and get all stabby on folks!

Actually, one thing I dig is if you look at the front lip spoiler, it looks like the rear spoiler but flipped upside-down. There is a nice design unity there.

Dale

 

Dale,

Now that you mentioned it, I see the similar lines between both spoilers. Cool!

Cheers,
George

 

 

Nick,

What sort of interesting aero stuff have you read lately?

I've been thinking about removing the OEM wing and either go spoiler-free or install this duck tail spoiler (below). This car is not mine, it was a different car at the repair shop. I dig this spoiler but having a bare derriere equally grows on me. I also suspect the benefits of a rear spoiler are negligible at typical highway speeds.

Cheers,
George

 

Well George, I have been researching larger aero packages, so I'm looking to go the other way with it and put something larger for more downforce and high speed stability. So, we're kind of working against eachother.

In saying that, I did see an interesting video which showed the difference between no spoiler, a '99 spoiler, and a GT wing from RE-Amemiya. The results are conclusive...


Think about it before a wing delete...

Nick

 

Nerd fact:
The 93-95 cars didn't come with a wing because technically, it is a spoiler



Edit-
I enjoyed the video. Thank you posting that

I a big fan of wingless FD's... For the street though

 

And today's winner of the Needless Semantics Award goes to...

Nick

 

Yup, the stock '93-95 rear wing is a "floating spoiler" because the airflow on the underside is only turbulent and not attached to the wing surface so the wing really just affects the airflow over the top of the "wing" for a spoiler affect (same effect as if you took soft foam and stuffed it between the wing and the trunk lid).

 

lol But actually not really as the two are very distinct pieces of equipment and not knowing the difference can be quite embarrassing in some circles. So I'm just trying to educate (I know, I know what can I say? the engineer in me refuses to use the two terms interchangeably.)

A wing vs a spoiler:

https://wheelsnwings.wordpress.com/2...iler-and-wing/

 

Fair enough. I am interested in a wing personally and I can understand now the distinguished difference between.

Thank you!

Nick

 

Nick,

No offense taken and thanks for the video. What's with the guy splashing the driver with soapy water? Thought that was comical. Anyway, there is a benefit to a rear wing otherwise they would not be a popular add-on. Its benefit does depend upon the driver's intended use of the car. For example, the 99+ or GT Wing from the video makes good sense on a dedicated track car. Unless I am mistaken, wouldn't a wing or spoiler have less effect at or below highway speeds? Does the OEM spoiler truly provide any benefit or is it more for asthetics?

Blue TII,

If the OEM spoiler generates turbulent air between the body and underside of the spoiler then wouldn't that effectively generate lift? I think about the spoiler on an airplane...once it is deployed, the air flowing over it becomes disrupted (spoiled) and generates aerodynamic drag. This drag helps reduce wind speed over the airplane's wing and thus reduces overall airspeed. For a rear spoiler on a car, the principle should be the same - an air foil generating downward force (drag) to keep the rear wheels planted on the tarmac at high speeds.

In my circumstances, the car is used on auto-x or cruising the highway. I would love to put it on track one day, like VIR. I believe the weight penalty of the rear spoiler would outweigh any aerodynamic benefit at speeds less than 70MPH. Am I misunderstanding the concept? I never really gave it much thought until now.

Looks like it's time to use ye olde Search function! If you guys have some good references for me to read then feel free to post.

Cheers,
George

 

Montego,

Thanks for the link. You posted it as I was editing my above post. I need to re-read it again but I thought this excerpt has some merit: "Some spoilers are added to cars primarily for styling purposes and have either little aerodynamic benefit or even make the aerodynamics worse. The main design goal of a spoiler in passenger vehicles is to reduce drag and increase fuel efficiency. While many often imitate wings and airfoils, these serve mostly decorative purposes."

Again, I'd like to say that the benefit of using a wing or spoiler would depend upon the driver's application for the car.

Cheers,
George

 

It's really called a spoiler because the extra drag will cost you a half an MPG at freeway speeds.

 

Spoilers can also create downforce as they build a high pressure area in front of the spoiler.
Just like the front R1 spoiler, just like the windshield for that matter.

The #s we have for the FD only show the rear spoiler increases rear down force if you have an understanding of vehicle aerodynamics.

That is, the #s we have are for the base FD with no front spoiler and no rear wing and the R1 FD with front spoiler and rear "floating spoiler" and the #s show the R1 front lip decreases the Coefficient of Lift and the rear Coefficient of Lift stays the same.
It is only through knowing vehicle aerodynamics that we know if you ONLY decrease the front Coefficient of Lift with a front spoiler the rear Coefficient of Lift will increase due to the front of the vehicle being "pushed down".

Figures from Joseph Katz book
Baseline RX7____________RX7 - R-2
Drag Coefficient 0.29_______0.31
Lift Coefficient, front 0.16____0.10
Lift coefficient, rear 0.08_____0.08

Mazda's published aero figures for the 1991-1998 FD with R1/R2 Aero kit. (from Jack Yamaguchi RX-7 book)

These are obviously at a different wind speed as the #s vary from the above #s.

Drag coefficient, Cd = 0.31
Frontal area (A), sq meters/sw feet= 1.79/19.26
Cd X A, sq meters/sq feet= 0.55/5.98
Lift coefficient, front, Clf= 0.04
Lift coefficient, rear, Clf= 0.01

We can clearly see the opposite of this effect illustrated with the #s provided for the 1999 FD aero kit with the adjustable rear wing. The more rear down force dialed in the more front end lift occurs.

Mazda's published aero figures for the 1999-2002 FD with Aero kit. (from Jack Yamaguchi SAE article)

Drag coefficient, Cd = ?
Frontal area (A), sq meters/sw feet= ?
Cd X A, sq meters/sq feet= ?

Rear wing adjustable to 1,5, 10 and 14.5 degree settings.

Lift coefficient, front, Clf= 0.045 (with rear wing at 1 deg angle setting)
Lift coefficient, rear, Clf= 0.00 (with rear wing at 1 deg angle setting)

Lift coefficient, front, Clf= 0.047 (with rear wing at 5 deg angle setting)
Lift coefficient, rear, Clf= -0.025 (with rear wing at 5 deg angle setting)

Lift coefficient, front, Clf= 0.051 (with rear wing at 10 deg angle setting)
Lift coefficient, rear, Clf= -0.058 (with rear wing at 10 deg angle setting)

Lift coefficient, front, Clf= 0.053 (with rear wing at 14.5 deg angle setting)
Lift coefficient, rear, Clf= -0.075 (with rear wing at 14.5 deg angle setting)

 

Those definitions are crap...
Spoilers are not automotive-specific, many aircraft employ spoilers and I'm pretty sure their use on aircraft preceded automotive applications. On both aircraft and cars, they are used to reduce or "spoil" lift. They may also sometimes reduce drag on some cars, but usually they are employed primarily for lift reduction. Or marketing...

Wings are not "intended to increase drag". They are there to generate lift on aircraft and downforce on cars. Induced drag is a negative side-effect.

 

Here is a great thread that shows a video about the FD's rear spoiler affects on aerodynamics: RX7 FD Aerodynamics

It mainly discusses the differences between OEM spoiler and no spoiler. It has good wind tunnel footage so watch it from YouTube vice watching it within that thread. Credit goes to GraysGarage for posting it back in 13 Sep 2015.

Cheers,
George

 

Whoever designed this spoiler and the Eunos Cosmo interior was definitely a Trekie...

There are no coincidences.

 

jesse,

Nice! I think we are on to something here. Thanks for sharing!

Cheers,
George

 

My Cosmo looking like the TNG Enterprise Bridge is the reason I bought my first rotary in the late 90's. Not sure I should put that out in public, but there it is...

 

Too bad the Cosmo never came in a manual transmission. It is a real head turner!

 

The Cosmo did not need a manual transmission. It needed that 280hp gentlemens agreement to go away stock engine could have sat at 400hp with ease. Manual in a Cosmo would be just as lame as the 6 speed MKIV Supra(full second in 1/4mile slower than the AT), need AT for performance with a 20B's torque IMHO, and does not fit the Luxury coupe design intentions.

FD is manual or bust though no doubt.