Carrera Tail or Duck Tail...

[makaio]

I'm trying to decide between a Carrera Tea tray style tail or a Duck Tail. I like the look of the 911 without a tail, but I need the extra downforce. I already have the front spoiler. What is everyones comments? Which do you like better?

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Matt Chamblin
78 911 SC

[BlueSkyJaunte]

Duck tail looks cooler (IMHO) but produces greater drag. Really. All aftermarket ducktails that I've seen are a complete decklid replacement.

Carrera-type tails do not create as much drag but typically require drilling--so either get a spare decklid and attach your tail to that or sacrifice your pristine original one to the Downforce Gods.

I don't know if there's a difference in downforce between the two.

Personally I think the ducktail looks better on pre-'74 vehicles and the Carrera looks better on post-'74.

YMMV.

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blue
'81 SC Targa

[mark 74 carrera]

Duck. But I am biased. My car came with the duck tail.

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Mark Isaak
'74 Targa

[911pcars]

Between the two, the duck tail produces less downforce. Actually, downforce is sort of a misnomer as both reduce lift rather than create downforce. The end result though is the same, and that is to keep the rear end planted at high speeds, the "tea tray" does a slightly better job.



Appearance wise, it's your call.
Sherwood Lee
http://members.rennlist.org/911pcars

[Jack Olsen]

I like the look of the 911 without a tail, but I need the extra downforce.

Click on this thumbnail to see one alternative solution:



Downforce when you need it, and the fastback look when you don't.

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Jack Olsen
My Rennlist home page • My Pelican Gallery page • My Porsche Owners Gallery page

[This message has been edited by JackOlsen (edited 07-11-2001).]

[Bill Verburg]

Lift and drag are variables which move in step with one another, when one goes up so does the other, and vice versa. Sherwood Lee is correct the spoilers available for use on a 911 do not provide downforce, they only reduce lift(and drag) to varying degrees. Since this effect is most observable at speed, here are the lift #'s in lbs. for the 3 most common early types all at 150 mph
ducktail ~160
Carrera ~150
3.3 liter Turbo ~85
no spoiler ~295
The corresponding front #'s are
ducktail ~60
Carrera ~50
3.3 liter Turbo ~40
no spoiler ~145
ps great pic Sherwood! You really got all the ductails in a row!
pps I always liked the esthetics of the ducktail, its also lighter.

[rscupper]

I think the 'whale' tail (~'79 turbo?) would look great on an SC. I had one on my '74 Carrera & my previous '75 Carrera. Excellent aero advantage on the track and looks well proportioned with the rear flares. Otherwise, the 'sugar scoop' is a classic. Yep, your design call.

[pwd72s]

Deck lid spoilers? Heck, you guys just want to take all the fun & excitement out of doing 150! The whale tail is cool tho. Gives you a place to put your McDonalds lunch while dining out. I've often thought I should add one to my car.

[RaF944]

Its also a wonderful beer holder when you are drinking outside

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85.5 Porsche 944

[This message has been edited by RaF944 (edited 07-11-2001).]

http://www.fvd.de/katalog/aerodynamic_de.html

In my opinion the 1978 Turbo 3.3 spoiler is the best looking of them all. However it sometimes look a bit inappropriate on narrow SCs and Carreras. For a SC/Carrera I'd recommend a Carrera whale tail. Ducktails look best on pre 1974 cars.

BTW my 1984 Carrera has no rear spoiler.

[JohnnieA]

Duck!

[gaijinda]

I am no purest, but I like the duck tail on the lighter bumber '73 and earlier cars. For a '74 and later 911 I would go for the whale tail.

[Roland Kunz]

Hello

The Duck tail is the most efficient unit aviable.

The unit does not add additonal "face surface" to the car and lowers the CD while helping to pump air into the engine bay.

But Porsche hit a bad nerve with that and german burocracy forced them to make the new rubber liped spoilers. ( In fact each ducktail needed to have a single approval by TÜV, some costumers got there RS with a normal lid and the ducktail as a race track only item )

So they changed to the later style.
They needed to be much more wide and overstanding ( and add face value ) for thesame effect. The rubber lip will distord under high speed ( especially the aftermarked sold "flubber lips" ) and lower effectiness ( this is why race wings have no rubber tip ). Also the newer units have more wight.

Now with the 964, Porsche came back to the ducktailsystem. The TÜV will not allow to use that system without selfaktivation and as you can not ecedd 60 km/h in reverse it is legal ( Well the issue is runing against a child while backing up, the edge will hit the head ). So if you retrofit the 964 unit the TÜV will see the unit goes up and down like the original unit. A knob that lets you rise the unit must be overrided if you drive the car. A not working 964 spoiler gives you a bad point at the TÜV inspection and has to be fixed. Either if it will go up or not down. The good thing is they don´t testdrive to find out. But if you really run against a child while backing up ( this happens often as childs are not acting normal and you have no direct view ) or a bicycle driver hits you and the spoiler adds injurys you would be glad to have investet a handfull dollar more and have it done the right way.

Now if you say the RS came with a fixed wing then look close all RS came with a full working wing except the CUP with wasn´t a street legal car.

The general idear is to raise the upper windfiollevel as hig as possible following Wunibald Kamm´s researches ( Known as Kamm heck ).

Generally it says the longer the car the higer it´s speed ( or lower drag ).

This is theer reason why the 964 wing does not only drive up it also goes far back.

Grüsse

[makaio]

Thanks all! I have decided to go with the Duck Tail, even though my car is not the early body style. I've seen a couple of SC's with them, and they look good. Even with the bumper bellows.

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Matt Chamblin
78 911 SC

[911pcars]

How much lift is reduced with this rear spoiler?



Sherwood Lee
http://members.rennlist.org/911pcars

[pbs911]

Duck, Duck, Carrera


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Paul
78SC Targa

[jsmarcus]

How about using this "whale tail"?



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Josh
Black on Black '84 Carrera

[Bill Verburg]

Keep in mind LIFT AND DRAG are inextricably linked. The type of link is called direct variation when one goes up the other does also. Do not confuse with coefficient of drag or frontal area which are different, though related concepts. Here are the factory published graphs of lift.
FRONT

REAR

The reference to turbo is the early turbo spoiler which is quite similar to the SC/Carrera spoilers. The other references are self explanatory.

[stealthn]

Bill,

Thanks for the graphs, that's great!

What are the ramifications of just the front spoiler, I know you would eliminate the front lift, but does this increase this in the rear?

I know Porsche says to do them at the same time (Front and rear spoilers), but I have a Targa (yet another wind flow issue), and I never really liked a tail on a Targa. I have added front spoilers on other cars and this really helps in the front end, so I'd like to add the "smile" to mine.

Each to their own with tails, IMHO I like the appropriate tail for the years, but I like the turbo tail better than the Carrera tail on the 78-87 years.

Cheers

[Bill Verburg]

Front spoiler without a rear is not an issue. Some have reported instability when the reverse was tried, but I think that you would have to be going mighty fast for it to be an issue(never tried it myself). The f/r combo does help in strong side winds. I never liked the tea tray on a na aspirated car, even though it is the most efficient of the mid year spoilers.. I do agee that the ducktails(also called sugar scoops) look best on pre 74 cars