intro mr. duck tail
09-02-2016, 07:54 PM
#19
Rennlist Member
Doubtful if there are any meaningful stats regarding a ducktail on a 997, but in Paul Frere's "Porsche 911 Story" there us a chapter devoted to body developments which includes lift and drag coefficients of the '73 Carrera with and without the ducktail spoiler that were arrived at in wind tunnel testing.
Carrera RS with normal lid
Front lift at 152 mph - 70.6 lbs.
Rear lift at 152 mph - 145 lbs.
Carrera RS with ducktail rear spoiler
Front lift at 152 mph - 77.3 lbs.
Rear lift at 152 mph - 93 lbs.
So, the ducktail did not create downforce but it did reduce rear lift substantially. Also, the top speed was increased by 3 mph and a side benefit was that it created a high pressure area at the rear grill which enhanced engine cooling.
My experience on the street with three air-cooled 911's equipped with ducktails was that the cars were noticeably more stable at higher (70-85 mph) highway speeds, especially when crosswinds were present. Around 70 mph I could feel the spoiler starting to work.
On a 997, installing a ducktail would likely work about the same as the motorized spoilers on non-GT3's. Otherwise, Porsche would not have installed ducktails on the limited edition Sport Classic 997's. I considered putting one on my GT3 because I don't care for the looks of the stock 997.1 non-RS spoiler, plus I don't track my GT3. I eventually decided that I didn't want my car to lose it's "GT3-ness", so I left it as is. Being a big fan of the ducktail, that was not an easy choice.
Carrera RS with normal lid
Front lift at 152 mph - 70.6 lbs.
Rear lift at 152 mph - 145 lbs.
Carrera RS with ducktail rear spoiler
Front lift at 152 mph - 77.3 lbs.
Rear lift at 152 mph - 93 lbs.
So, the ducktail did not create downforce but it did reduce rear lift substantially. Also, the top speed was increased by 3 mph and a side benefit was that it created a high pressure area at the rear grill which enhanced engine cooling.
My experience on the street with three air-cooled 911's equipped with ducktails was that the cars were noticeably more stable at higher (70-85 mph) highway speeds, especially when crosswinds were present. Around 70 mph I could feel the spoiler starting to work.
On a 997, installing a ducktail would likely work about the same as the motorized spoilers on non-GT3's. Otherwise, Porsche would not have installed ducktails on the limited edition Sport Classic 997's. I considered putting one on my GT3 because I don't care for the looks of the stock 997.1 non-RS spoiler, plus I don't track my GT3. I eventually decided that I didn't want my car to lose it's "GT3-ness", so I left it as is. Being a big fan of the ducktail, that was not an easy choice.
09-03-2016, 01:23 PM
#21
Doubtful if there are any meaningful stats regarding a ducktail on a 997, but in Paul Frere's "Porsche 911 Story" there us a chapter devoted to body developments which includes lift and drag coefficients of the '73 Carrera with and without the ducktail spoiler that were arrived at in wind tunnel testing.
Carrera RS with normal lid
Front lift at 152 mph - 70.6 lbs.
Rear lift at 152 mph - 145 lbs.
Carrera RS with ducktail rear spoiler
Front lift at 152 mph - 77.3 lbs.
Rear lift at 152 mph - 93 lbs.
So, the ducktail did not create downforce but it did reduce rear lift substantially. Also, the top speed was increased by 3 mph and a side benefit was that it created a high pressure area at the rear grill which enhanced engine cooling.
My experience on the street with three air-cooled 911's equipped with ducktails was that the cars were noticeably more stable at higher (70-85 mph) highway speeds, especially when crosswinds were present. Around 70 mph I could feel the spoiler starting to work.
On a 997, installing a ducktail would likely work about the same as the motorized spoilers on non-GT3's. Otherwise, Porsche would not have installed ducktails on the limited edition Sport Classic 997's. I considered putting one on my GT3 because I don't care for the looks of the stock 997.1 non-RS spoiler, plus I don't track my GT3. I eventually decided that I didn't want my car to lose it's "GT3-ness", so I left it as is. Being a big fan of the ducktail, that was not an easy choice.
Carrera RS with normal lid
Front lift at 152 mph - 70.6 lbs.
Rear lift at 152 mph - 145 lbs.
Carrera RS with ducktail rear spoiler
Front lift at 152 mph - 77.3 lbs.
Rear lift at 152 mph - 93 lbs.
So, the ducktail did not create downforce but it did reduce rear lift substantially. Also, the top speed was increased by 3 mph and a side benefit was that it created a high pressure area at the rear grill which enhanced engine cooling.
My experience on the street with three air-cooled 911's equipped with ducktails was that the cars were noticeably more stable at higher (70-85 mph) highway speeds, especially when crosswinds were present. Around 70 mph I could feel the spoiler starting to work.
On a 997, installing a ducktail would likely work about the same as the motorized spoilers on non-GT3's. Otherwise, Porsche would not have installed ducktails on the limited edition Sport Classic 997's. I considered putting one on my GT3 because I don't care for the looks of the stock 997.1 non-RS spoiler, plus I don't track my GT3. I eventually decided that I didn't want my car to lose it's "GT3-ness", so I left it as is. Being a big fan of the ducktail, that was not an easy choice.
09-03-2016, 06:28 PM
#23
Burning Brakes
Thread Starter
thanks a lot guys .. drove it today for 250miles .. feels very stable even at speeds past 170mph .. so I think there is enough downforce generated with that duck tail
09-05-2016, 12:11 PM
#24
Rennlist Member
11-06-2016, 11:41 AM
#28
Burning Brakes
Thread Starter
Originally Posted by 993Brendan
Looks really great man. Happened upon your car at Cars and Coffee on Saturday in Nashville and thought the look was really clean in person.
11-08-2016, 11:09 AM
#30
Just thinking out loud... could you get a similar effect running the .2RS lid without the uprights and wing? Benefit there is easily being able to add them for track days but less conspicuous on the street.
