M5POST
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read

Go Back   M5POST - BMW M5 Forum > F10 M5 Forum > BMW M5 (F10) General Forum

Post Reply
 
Thread Tools Search this Thread
      04-02-2013, 09:45 PM   #1
(H)
Lieutenant
(H)'s Avatar
United_States
156
Rep
592
Posts

Drives: F80 M3 (after F10 M5 ;-)
Join Date: Mar 2013
Location: Now Boca Raton, FL

iTrader: (0)

So what really is the deal with the trunk spoiler ...?

Dear Aerodynamics Specialists

Nugent’s reply to my “Understated Wolf …?” response made me thinking: What really is the deal with the trunk spoiler on the F10 M5? This lip is so small that I seriously couldn’t believe that it would make any difference in rear axle down pressure through aerodynamics. I still believe that this spoiler is a design element rather than a functional detail. So I started digging around the web trying to find some more information. Seems impossible!

All I found were German language online fora with people guessing around about the possible additional weight ratio that this rear lip would produce. The opinions ranged from around an additional 10lb at 100mph to 120lb (I would think that the latter one is way too much). Another theory was that the rear spoiler is in fact not a spoiler but a break-away edge for the airflow. Instead of creating additional down-pressure it prevents the airflow from lifting the rear end of the car at high speeds. The only official statement that I could find from BMW was a quote from Dr. Friedrich Nitschke, CEO of M GmbH who mentioned during the introduction of the M550d that body changes to the standard models were only made were technically absolutely necessary (referencing the rear spoiler on that vehicle). But again, I couldn’t find any detail on how or why that is technically necessary.

I will continue my research and keep you posted. But in the meantime, does anybody have more insight?

Best,
(H)

P.S.: Btw., the official German BMW explanation talks about the Gurney-Style of the spoiler. Does anybody know what that stands for – never heard it before.

P.P.S.: I was floored to read that 68% of newly registered 5 series BMW in Germany in 2011 had Diesel engines!

Name:  spoiler.jpg
Views: 792
Size:  467.1 KB
picture courtesy of euromotorsport.com
Appreciate 0
      04-02-2013, 11:21 PM   #2
chudak18
Captain
chudak18's Avatar
United_States
68
Rep
991
Posts

Drives: E92 335, W463 G55
Join Date: Jul 2010
Location: Vineland, NJ

iTrader: (3)

Garage List
Good theory. I can't imagine it has much technical purpose since M sells a sport wing that looks larger and i would assume will change the dynamics. Again this is all theory, no concrete info. Good hunting
Appreciate 0
      04-03-2013, 12:24 AM   #3
absix
Mu mu muh muli, maikouuu!
absix's Avatar
86
Rep
1,286
Posts

Drives: F10 M5; F25 2.0d;
Join Date: Feb 2008
Location: Europe

iTrader: (10)

Quote:
Originally Posted by (H) View Post
P.P.S.: I was floored to read that 68% of newly registered 5 series BMW in Germany in 2011 had Diesel engines!
It's not only BMW and it's not only the 5 series. Pretty much the same numbers across Europe, in some countries it is even higher percentage. The petrol prices here are quite a bit different than the prices in the US - eg. for $3.2 someone in Germany gets 1 liter, you get almost 4 (a gallon) Some people need to drive a lot.
__________________
Appreciate 0
      04-03-2013, 12:28 AM   #4
nugent
Captain
nugent's Avatar
United_States
65
Rep
602
Posts

Drives: f10 m5
Join Date: Apr 2011
Location: san francisco

iTrader: (0)

it's similar in design to the e9x spoiler. if memory serves, and mine usually does, I remember reading at some point that it decreases wind turbulence at high speed. not really creating downforce but more for limiting destabilizing forces.
__________________
e92 m3 6MT, RS4 6MT, S4 Avant 6MT, WRX 5MT, Corsica

Appreciate 0
      04-03-2013, 01:19 AM   #5
wisesoul
Savoir Faire
wisesoul's Avatar
Philippines
74
Rep
1,772
Posts

Drives: 2013 BMW M5
Join Date: Aug 2010
Location: Los Angeles, Ca

iTrader: (0)

Aesthetically, it separates normal F10s from the M5, dating back from the E39. Just a signature touch.. I wouldn't dismiss its aerodynamic properties. It looks prominent enough to do something at speed. We need a wind tunnel to know for sure, just my take.
__________________
Current: Alpine White F10 M5|H&R springs|12mm/10mm spacers|Eisenmann Race
Sold:Imola Yellow RS4-KW V3|MTM 10mm spacers|Hotchkis rear sway bar|APR Stage 1|Milltek Catless|RNS-E|Euro RS4 Flat bottom Steering Wheel
Sold:E46 323i
Appreciate 0
      04-03-2013, 05:36 AM   #6
PatrickC23
Colonel
PatrickC23's Avatar
United_States
183
Rep
2,245
Posts

Drives: '16 991.1 911 GTS, '16 F85 X5M
Join Date: Apr 2012
Location: NNJ

iTrader: (0)

Garage List
2013 BMW ///M5  [0.00]
Quote:
Originally Posted by wisesoul View Post
Aesthetically, it separates normal F10s from the M5, dating back from the E39. Just a signature touch.. I wouldn't dismiss its aerodynamic properties. It looks prominent enough to do something at speed. We need a wind tunnel to know for sure, just my take.
Heres to more justification in buying the M performance spoiler
Appreciate 0
      04-03-2013, 06:26 AM   #7
NISFAN
Major General
NISFAN's Avatar
United Kingdom
3486
Rep
9,709
Posts

Drives: BMW M2
Join Date: Aug 2012
Location: Bedford UK

iTrader: (0)

This device doesn't produce down force, it reduces the tendency for the body to generate lift. Same outcome in a way but not strictly the same.

The clue is in the name 'trunk spoiler', spoiler is a lift disrupting device, as opposed to a 'wing' which is a lift/down-force generating device.

As for estimates of 120lb of reduced lift @ 100MPH. Do you really think that the car will ride up at the back as if it is lifted with a 120lb force? If so BMW sure suck at designing the break away on the rear trunk of the standard un-spoilered car.

My view, is yes it reduces lift by some value...would you notice the difference? Nope!!! It will also induce more drag at high speeds.....again would the driver notice the difference? Nope!!! So IMO it is 80% visual / 20% functional .....at best
Appreciate 0
      04-03-2013, 09:35 AM   #8
nugent
Captain
nugent's Avatar
United_States
65
Rep
602
Posts

Drives: f10 m5
Join Date: Apr 2011
Location: san francisco

iTrader: (0)

Quote:
Originally Posted by NISFAN
This device doesn't produce down force, it reduces the tendency for the body to generate lift. Same outcome in a way but not strictly the same.

The clue is in the name 'trunk spoiler', spoiler is a lift disrupting device, as opposed to a 'wing' which is a lift/down-force generating device.

As for estimates of 120lb of reduced lift @ 100MPH. Do you really think that the car will ride up at the back as if it is lifted with a 120lb force? If so BMW sure suck at designing the break away on the rear trunk of the standard un-spoilered car.

My view, is yes it reduces lift by some value...would you notice the difference? Nope!!! It will also induce more drag at high speeds.....again would the driver notice the difference? Nope!!! So IMO it is 80% visual / 20% functional .....at best
zacly, like I said.
__________________
e92 m3 6MT, RS4 6MT, S4 Avant 6MT, WRX 5MT, Corsica

Appreciate 0
      04-03-2013, 09:49 AM   #9
bobblehead
Brigadier General
bobblehead's Avatar
Canada
256
Rep
4,721
Posts

Drives: warp speed
Join Date: Aug 2009
Location: Toronto, On

iTrader: (0)

all along, I thought that spoiler added 3 extra hp to the car
Appreciate 0
      04-03-2013, 03:05 PM   #10
Northern X5M
Captain
Northern X5M's Avatar
Canada
104
Rep
806
Posts

Drives: 2014 Tanzanite Blue M5
Join Date: Oct 2010
Location: Edmonton, Alberta, Canada

iTrader: (0)

Quote:
Originally Posted by bobblehead View Post
all along, I thought that spoiler added 3 extra hp to the car
"Right you are, Ken!"
__________________
2014 ///M5 CP Tanzanite Blue/Cohiba - 11.15 @ 128.8 & 1.84 60' (2150' DA) - BPM Tune - MSR Intake - SSP DCT - SS DPs & HFC Mid Pipes/X-Over - E Race Muffs - 19" MT DRs... On to a new home.
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 03:54 PM.




m5post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST