Definitive Scientific Study of Spoiler Effect
#1
08-02-2018, 04:34 PM
Definitive Scientific Study of Spoiler Effect
On the round trip to and from the dealer today I monitored the MPG instant readout for approximately 20 miles with the spoiler deployed and 20 miles with it retracted, all the time with the cruise control set at 71 MPH and the car in dynamic mode without the sport function selected. (Funny thing is my spoiler doesn't deploy until the speedo reaches 72). Anyway, the road (not less) traveled is entirely at sea level and no elevation changes are encountered except for the occasional bridge, so I would conclude that the results are beyond question and can be deemed settled science.
With spoiler retracted, MPG fluctuated between 29 and 32, mostly toward 29 and 30;
With spoiler deployed MPG fluctuated between 29 and 33, but tended predominantly upwards of 30.
This is exactly the opposite of what I expected and means absolutely nothing of consequence.
Thus, I will proceed no further down this road less traveled and conclude with my apologies to M. Scott, may he RIP.
With spoiler retracted, MPG fluctuated between 29 and 32, mostly toward 29 and 30;
With spoiler deployed MPG fluctuated between 29 and 33, but tended predominantly upwards of 30.
This is exactly the opposite of what I expected and means absolutely nothing of consequence.
Thus, I will proceed no further down this road less traveled and conclude with my apologies to M. Scott, may he RIP.
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Uncle Fishbits (09-24-2021)
#3
08-02-2018, 06:13 PM
Senior Member
#4
08-02-2018, 07:05 PM
I remember reading an article in one of the major car magazines back in the late 80s while sitting in a doctor's waiting room. It was about the trend at the time of manufacturers offering optional rear spoilers on just about everything. The magazine tested the effects of rear spoilers on a half dozen new model cars and I remember the definitive conclusion: "There was no place within the United States where it was legal to drive anywhere close to fast enough to get any appreciable performance benefit from an optional rear spoiler." They determined that you had to be going 80 to 120 mph before they could get any measurable downforce on the rear wheels and even at the car's top speeds (it was the 80s after all), the effects were negligible.
#5
08-02-2018, 07:36 PM
Senior Member
#6
08-02-2018, 08:46 PM
At what speed does the F-Type start complaining if the spoiler is disabled? I suspect that's the speed at which it starts being effective.
#7
08-02-2018, 08:59 PM
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It was also a similar body shape. Also recall the Audi TT recall, where the previously optional rear spoiler was retrofitted to improve stability at high speeds. The spoiler was only part of it, but the reacall notes the issue is " AT SPEEDS SUBSTANTIALLY ABOVE POSTED SPEED LIMITS".
At what speed does the F-Type start complaining if the spoiler is disabled? I suspect that's the speed at which it starts being effective.
At what speed does the F-Type start complaining if the spoiler is disabled? I suspect that's the speed at which it starts being effective.
But I posted somewhere else about an Oz recall saying something about the spoiler needing to be up at 123 mph or thereabouts (I can't remember the exact figure ATM).
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#8
08-02-2018, 09:18 PM
Senior Member
Hello all,
just the other day I was driving highway and my dash light kept flicking that my trunk was open, I was going between 85 and 95 MPH.
My question is if the spoiler is there to add stability to the rear end of the car at fast speeds by putting downward pressure on the wheels as road force weight, then why would it not keep the trunk lid pushed down so the lid would not flicker the whole trip being open. When I finally did stop and checked the trunk lid it was not even like the lid was not latched it was latched but not locked down tight (latched, the lid would not open up farther without pushing the button to open).
I would think if the spoiler was designed to put downward force on the rear end of the car it would be able to exert enough downward pressure to keep the trunk lid down.!
Makes me wonder how effective the spoiler really is, other than a cool looking piece of useless metal artwork!
Just saying...
Happy Motoring...
just the other day I was driving highway and my dash light kept flicking that my trunk was open, I was going between 85 and 95 MPH.
My question is if the spoiler is there to add stability to the rear end of the car at fast speeds by putting downward pressure on the wheels as road force weight, then why would it not keep the trunk lid pushed down so the lid would not flicker the whole trip being open. When I finally did stop and checked the trunk lid it was not even like the lid was not latched it was latched but not locked down tight (latched, the lid would not open up farther without pushing the button to open).
I would think if the spoiler was designed to put downward force on the rear end of the car it would be able to exert enough downward pressure to keep the trunk lid down.!
Makes me wonder how effective the spoiler really is, other than a cool looking piece of useless metal artwork!
Just saying...
Happy Motoring...
#9
08-03-2018, 12:35 AM
Veteran Member
The spoiler on the F-type does not create downforce. It reduces the lift created by the car's shape when speed is high enough.
The spoiler works exactly in the same way as a spoiler on the top of an airplane wing. The spolier is also called a "lift dumper", and makes shure the wings lift is reduced just after touching down when landing.
Can be seen at 1:20 in this video:
"Spoiler or lift dumper is a device intended to reduce lift in an aircraft. Spoilers are on the top surface of a wing which can be extended upward into the airflow and spoil it. Spoilers reduce lift as well as increasing drag."
The spoiler works exactly in the same way as a spoiler on the top of an airplane wing. The spolier is also called a "lift dumper", and makes shure the wings lift is reduced just after touching down when landing.
Can be seen at 1:20 in this video:
"Spoiler or lift dumper is a device intended to reduce lift in an aircraft. Spoilers are on the top surface of a wing which can be extended upward into the airflow and spoil it. Spoilers reduce lift as well as increasing drag."
Last edited by Arne; 08-03-2018 at 12:56 AM.
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dmchao (08-03-2018)
#10
08-03-2018, 01:56 AM
This jaguar link (last FAQ) refers to a wing on the SVR Compared “spoiler” on the other models.
https://www.jaguar.co.uk/about-jagua...ftype-svr.html
Also a direct quote from the jaguar brochure (2016 Coupe) -
“a deployable rear spoiler rises at higher speeds to reduce lift by up to 264 lbs”
And also found this (again another direct paste from jaguar brochure) -
AERODYNAMIC SPOILER
The aerodynamic spoiler is integral to the enhanced performance of the F-TYPE SVR. Compared with the standard F-TYPE Coupe rear spoiler, the F-TYPE SVR produces more downforce but crucially less drag. The active spoiler is more elevated and wider than the standard F-TYPE Coupe spoiler, enabling it to act over the whole width of the car.
Air passes both over and under the spoiler, allowing Bernoulli's principle to act in the car's favor, faster moving air underneath the spoiler is at a lower pressure than that passing over the top, resulting in additional downforce.
The F-TYPE SVR spoiler operates in two different positions:
On the Coupe the aerodynamic spoiler deploys at 70 mph and stores at 50 mph
On the Convertible the aerodynamic spoiler deploys at 60 mph and stores at 40 mph
DEPLOYED SPOILER
When the F-TYPE SVR spoiler is deployed it increases downforce for greater stability and improved handling at top speed. In this position the spoiler gives a drag coefficient reduction of 2.5 percent and a lift coefficient reduction of 15 percent.
STORED SPOILER
For maximum top speed (V-Max), the spoiler is stored to reduce drag. It works in conjunction with the front spoiler and other aerodynamic enhancements to bring a drag coefficient improvement of 7.5 percent and lift coefficient reduction of 45 percent.
V-MAX
In order to achieve 200 mph†*3 you must consciously prepare your F-TYPE SVR. Select 'Dynamic Mode' and press the deployable aerodynamic spoiler switch for 3 seconds to enable V-Max Mode. While active, a permanent symbol appears on the instrument cluster. In this mode the spoiler remains stored at all speeds keeping drag to a minimum.
REAR UNDERFLOOR AND DIFFUSER
The smooth rear underfloor reduces drag, while the rear diffuser works with the rear underfloor to manage airflow, adding to the stability of the F-TYPE SVR.
BROCHURE LINK - https://images.jazelc.com/uploads/ga...m97-366026.pdf
https://www.jaguar.co.uk/about-jagua...ftype-svr.html
Also a direct quote from the jaguar brochure (2016 Coupe) -
“a deployable rear spoiler rises at higher speeds to reduce lift by up to 264 lbs”
And also found this (again another direct paste from jaguar brochure) -
AERODYNAMIC SPOILER
The aerodynamic spoiler is integral to the enhanced performance of the F-TYPE SVR. Compared with the standard F-TYPE Coupe rear spoiler, the F-TYPE SVR produces more downforce but crucially less drag. The active spoiler is more elevated and wider than the standard F-TYPE Coupe spoiler, enabling it to act over the whole width of the car.
Air passes both over and under the spoiler, allowing Bernoulli's principle to act in the car's favor, faster moving air underneath the spoiler is at a lower pressure than that passing over the top, resulting in additional downforce.
The F-TYPE SVR spoiler operates in two different positions:
On the Coupe the aerodynamic spoiler deploys at 70 mph and stores at 50 mph
On the Convertible the aerodynamic spoiler deploys at 60 mph and stores at 40 mph
DEPLOYED SPOILER
When the F-TYPE SVR spoiler is deployed it increases downforce for greater stability and improved handling at top speed. In this position the spoiler gives a drag coefficient reduction of 2.5 percent and a lift coefficient reduction of 15 percent.
STORED SPOILER
For maximum top speed (V-Max), the spoiler is stored to reduce drag. It works in conjunction with the front spoiler and other aerodynamic enhancements to bring a drag coefficient improvement of 7.5 percent and lift coefficient reduction of 45 percent.
V-MAX
In order to achieve 200 mph†*3 you must consciously prepare your F-TYPE SVR. Select 'Dynamic Mode' and press the deployable aerodynamic spoiler switch for 3 seconds to enable V-Max Mode. While active, a permanent symbol appears on the instrument cluster. In this mode the spoiler remains stored at all speeds keeping drag to a minimum.
REAR UNDERFLOOR AND DIFFUSER
The smooth rear underfloor reduces drag, while the rear diffuser works with the rear underfloor to manage airflow, adding to the stability of the F-TYPE SVR.
BROCHURE LINK - https://images.jazelc.com/uploads/ga...m97-366026.pdf
Last edited by Kdes; 08-03-2018 at 02:40 AM.
#11
08-03-2018, 11:26 AM
Veteran Member
On the round trip to and from the dealer today I monitored the MPG instant readout for approximately 20 miles with the spoiler deployed and 20 miles with it retracted, all the time with the cruise control set at 71 MPH and the car in dynamic mode without the sport function selected. (Funny thing is my spoiler doesn't deploy until the speedo reaches 72). Anyway, the road (not less) traveled is entirely at sea level and no elevation changes are encountered except for the occasional bridge, so I would conclude that the results are beyond question and can be deemed settled science.
With spoiler retracted, MPG fluctuated between 29 and 32, mostly toward 29 and 30;
With spoiler deployed MPG fluctuated between 29 and 33, but tended predominantly upwards of 30.
This is exactly the opposite of what I expected and means absolutely nothing of consequence.
Thus, I will proceed no further down this road less traveled and conclude with my apologies to M. Scott, may he RIP.
With spoiler retracted, MPG fluctuated between 29 and 32, mostly toward 29 and 30;
With spoiler deployed MPG fluctuated between 29 and 33, but tended predominantly upwards of 30.
This is exactly the opposite of what I expected and means absolutely nothing of consequence.
Thus, I will proceed no further down this road less traveled and conclude with my apologies to M. Scott, may he RIP.
Last edited by Unhingd; 08-03-2018 at 11:37 AM.
#12
08-03-2018, 01:29 PM
Senior Member
There is this misconception that spoiler and wings work by being pressed down from the air while the real factor is the pull effect instead. For an airplane wing, the upwards force is NOT from the air compressed below the wing but by the lift on the upside, reverse that on a car spoiler. Think of suction rather than compression. Arne is right on target.
A properly fitted front splitter diverts the ai from going under the car (and Jaguar should have larger hood vents to evacuate the air from the front grille), Aston has that right.
A properly fitted front splitter diverts the ai from going under the car (and Jaguar should have larger hood vents to evacuate the air from the front grille), Aston has that right.
Last edited by FType17; 08-03-2018 at 03:08 PM.
#13
08-03-2018, 03:00 PM
Veteran Member
#16
08-03-2018, 06:19 PM
Senior Member
#17
08-03-2018, 06:21 PM
Senior Member
#19
08-03-2018, 09:35 PM
Veteran Member
There is this misconception that spoiler and wings work by being pressed down from the air while the real factor is the pull effect instead. For an airplane wing, the upwards force is NOT from the air compressed below the wing but by the lift on the upside, reverse that on a car spoiler. Think of suction rather than compression. Arne is right on target.
A properly fitted front splitter diverts the ai from going under the car (and Jaguar should have larger hood vents to evacuate the air from the front grille), Aston has that right.
A properly fitted front splitter diverts the ai from going under the car (and Jaguar should have larger hood vents to evacuate the air from the front grille), Aston has that right.
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FType17 (08-03-2018)
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