M.Bonanni Project 370Z V3.0 | Clean Slate

M.Bonanni · 09-09-2011, 02:03 PM

Quote:

Originally Posted by travisjb

how about practing your launch? not a natural act for TT / road race guys

I started as a drag racer back in 2001....shhhhh....

I am not planning on doing a traditional drag style launch, but more of a roll off start instead. A drag style launch, done perfectly in a Z is tough, especially if your tires are aired up to a high PSI like mine will be for reduced rolling resistance. I think a drag style launch can hurt me more than it can help me if its not done absolutely perfectly. Plus the shock of a traditional launch is hard on the car.

travisjb · 09-09-2011, 02:42 PM

... not that there's anything wrong with that! haha

okay, another possible easy add on idea... vortex generators strategically placed to help with airflow separation on roofline and rolling off the rear hatch

these just showed up at my house this afternoon, in fact... now that I have no aero restrictions will be going on the car

also, can you ditch the side mirrors for the event? maybe that's taking it too far?

travisjb · 09-09-2011, 02:45 PM

Following back up on an earlier topic... I measured my camber at last weekend's event... sure enough, the SPC arms did NOT hold camber... left measured ~1 degree, right ~3 degrees... unfortunately opposite of what I needed for a clockwise event

M.Bonanni · 09-09-2011, 02:57 PM

The vortex generators might actually be something worth trying. Seems you can find universal ones pretty cheap online. Here's a link for a set of 10 for $20...

Amazon.com: Vortekz Universal Vortex Generators Black 10 Pieces: Everything Else

Which ones did you get?

As for the mirrors, I have to drive the car to and from the event (about a 3.5 hour trip each way from Vegas) so I definitely want them on there for that. Probably too much hassle for what its worth to do at the event or between runs but you never know. If I am within 1 mph of my goal then I may just be persuaded to take them off.

travisjb · 09-09-2011, 03:01 PM

I splurged for the ones that are proven to work on low-speed aircraft...

STOLSPEED VORTEX GENERATORS from Aircraft Spruce

$100 pack is probably enough to cover 2-3 cars, so I'll have some left over... but won't know until I get my car back in a few weeks - otherwise I'd send you half

M.Bonanni · 09-09-2011, 03:11 PM

Those are super tiny! Wondering if bigger ones are usually used on cars because of the lower speeds or because they are usually positioned on the roof instead of on a wing. Hmmm... may have to try and speak with people who are smarter than I on this one.

Doing some quick reading, choosing the correct height of a vortex generator depends on the thickness of the boundary layer of air where you plan on placing the fins. You want the same height fin as thickness of the boundary layer. Wondering if the profile of a car creates a much thicker boundary layer over the roofline of a car than an airplane wing creates over the top of its surface. Furthermore, if these work on the top of an airplane wing, wouldn't they then work on the bottom of a car wing to increase efficiency? Can't say I have ever seen that done before...

travisjb · 09-09-2011, 04:20 PM

my understanding... they are used on a wing to help when the AoA exceeds 15% or so... they keep the flow more efficient in that situation in particular... for that reason, i'm not sure how useful they'd be on the underside of our wings... a question for the more educated on this subject for sure

re small fins... what I plan to do is put them a little further afield in the airstream where the boundary layer remains thin...

... but it would be nice to have some data that helps us understand how high the fins should be

these are used on kit aircraft by the way... those things cruise at 150-175

ChipsWithDips · 09-09-2011, 04:29 PM

Autospeed has quite a few aero articles related to this sort of discussion

Vortex Generator 4 part series (They specifically test the vortex generators on the underside too):
Vortex 1
Vortex 2
Vortex 3
Vortex 4
Also in that article they show some data from Mistu EVO tests that seems to suggest that 25mm high or so is best.

Aero Testing 5 part series:
Aero 1
Aero 2
Aero 3
Aero 4
Aero 5

Underflow 2 Part Series:
Under car 1
Under car 2

travisjb · 09-09-2011, 05:40 PM

thanks for the links... 1" vertical fin is the takeaway huh?

if true, wonder if there's any use for those 0.45" vortex generators I bought?

ChipsWithDips · 09-09-2011, 05:57 PM

Quote:

Originally Posted by travisjb

thanks for the links... 1" vertical fin is the takeaway huh?

if true, wonder if there's any use for those 0.45" vortex generators I bought?

Who knows, maybe our boundary layer is thinner because our cars are so slick.

Feel like doing some tuft testing?

M.Bonanni · 09-09-2011, 06:59 PM

Awesome articles Chips! Thanks for the links!

Now, if we could only find some wind tunnel photos of a stock 370Z...

travisjb · 09-09-2011, 09:06 PM

fun reading... don't know if you guys actually read through all those links but I'm going through now... friday night for married guys! any event, you'll notice from the excerpt below that the 15mm height when using a delta wing style vortex generator is within ~10% of the coefficient of lift benefit of the 25mm height... in other words, the VGs I bought should work fine... clearly on the EVO this test came from it was the right decision to go with 25mm... and I'm curious what 35mm would have looked like - unfortunately they didn't test it... but 15mm gets me 90% of the way there

I suspect we also have a tighter boundary layer vs evo, given our less steeply slopped windshield and overall better aero, which would just reinforce the choice to get a smaller VG than used on the EVO

Quote:

This graph shows the test results of the delta shaped vortex generators. The tested height of these vortex generators were again 15, 20 and 25mm. The test results showed a similar decrease in drag and lift coefficients of 0.006 for 15 and 20mm delta vortex generators. For 25mm high deltas the drag decrease remained much the same but the coefficient of lift decreased by 0.007.

M.Bonanni · 09-09-2011, 09:15 PM

Just finished reading all of the links myself. Very good stuff in there. Making me re-think my front air dam now too...

I do think that the Z's shape can probably get away with a shorter VG, but now I am wondering if the VGs are even going to make any positive difference at all.

travisjb · 09-09-2011, 09:44 PM

even more disturbing... our car is a wing! look

travisjb · 09-09-2011, 09:52 PM

I'm kidding with that last post btw!

Some of my (poorly educated) theories

- nissan was right to put the spoiler lip on the back... exactly because of the picture above... if they didn't there would be a lift effect of higher pressure below car vs above

- my car has a rear diffuser... I actually want the air to stay "attached" on the rear deck lid and to then flow under the rear wing... it will theoretically then "re-attach" with the high speed air coming from the rear diffuser and the air coming out of the rear diff cooler box... I want all that to be as laminar as possible to minimize drag... I also want all that to hug the surface of the rear deck lid to avoid having turbulent air come in contact with the wing... that part I can be certain of... goal is to get high speed 'clean air' to the wing and keep all the turbulent air associated with roof and boundary separation 12" below the wing

- therefore I need VGs at the rear roof

- therefore I need VGs on the rear decklid

What I don't know... do I need VGs on the front wind splitter? do I need VGs on the leading edge of the rear diffuser?

09-09-2011, 02:42 PM	#2 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 190	... not that there's anything wrong with that! haha okay, another possible easy add on idea... vortex generators strategically placed to help with airflow separation on roofline and rolling off the rear hatch these just showed up at my house this afternoon, in fact... now that I have no aero restrictions will be going on the car also, can you ditch the side mirrors for the event? maybe that's taking it too far? __________________ 2009 370Z #104 For Sale

09-09-2011, 02:45 PM	#3 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 190	Following back up on an earlier topic... I measured my camber at last weekend's event... sure enough, the SPC arms did NOT hold camber... left measured ~1 degree, right ~3 degrees... unfortunately opposite of what I needed for a clockwise event __________________ 2009 370Z #104 For Sale

09-09-2011, 02:57 PM	#4 (permalink)
M.Bonanni The370Z.com Sponsor Join Date: Nov 2008 Location: Las Vegas Posts: 2,575 Drives: Fast Rep Power: 1322	The vortex generators might actually be something worth trying. Seems you can find universal ones pretty cheap online. Here's a link for a set of 10 for $20... Amazon.com: Vortekz Universal Vortex Generators Black 10 Pieces: Everything Else Which ones did you get? As for the mirrors, I have to drive the car to and from the event (about a 3.5 hour trip each way from Vegas) so I definitely want them on there for that. Probably too much hassle for what its worth to do at the event or between runs but you never know. If I am within 1 mph of my goal then I may just be persuaded to take them off. __________________ MikeBonanni.com Twitter: http://www.twitter.com/MikeBonanni Facebook: http://www.facebook.com/MBonanni36 Function > Form

09-09-2011, 03:01 PM	#5 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 190	I splurged for the ones that are proven to work on low-speed aircraft... STOLSPEED VORTEX GENERATORS from Aircraft Spruce $100 pack is probably enough to cover 2-3 cars, so I'll have some left over... but won't know until I get my car back in a few weeks - otherwise I'd send you half __________________ 2009 370Z #104 For Sale

09-09-2011, 03:11 PM	#6 (permalink)
M.Bonanni The370Z.com Sponsor Join Date: Nov 2008 Location: Las Vegas Posts: 2,575 Drives: Fast Rep Power: 1322	Those are super tiny! Wondering if bigger ones are usually used on cars because of the lower speeds or because they are usually positioned on the roof instead of on a wing. Hmmm... may have to try and speak with people who are smarter than I on this one. Doing some quick reading, choosing the correct height of a vortex generator depends on the thickness of the boundary layer of air where you plan on placing the fins. You want the same height fin as thickness of the boundary layer. Wondering if the profile of a car creates a much thicker boundary layer over the roofline of a car than an airplane wing creates over the top of its surface. Furthermore, if these work on the top of an airplane wing, wouldn't they then work on the bottom of a car wing to increase efficiency? Can't say I have ever seen that done before... __________________ MikeBonanni.com Twitter: http://www.twitter.com/MikeBonanni Facebook: http://www.facebook.com/MBonanni36 Function > Form Last edited by M.Bonanni; 09-09-2011 at 03:31 PM.

09-09-2011, 04:20 PM	#7 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 190	my understanding... they are used on a wing to help when the AoA exceeds 15% or so... they keep the flow more efficient in that situation in particular... for that reason, i'm not sure how useful they'd be on the underside of our wings... a question for the more educated on this subject for sure re small fins... what I plan to do is put them a little further afield in the airstream where the boundary layer remains thin... ... but it would be nice to have some data that helps us understand how high the fins should be these are used on kit aircraft by the way... those things cruise at 150-175 __________________ 2009 370Z #104 For Sale Last edited by travisjb; 09-09-2011 at 04:22 PM.

09-09-2011, 04:29 PM	#8 (permalink)
ChipsWithDips Enthusiast Member Join Date: Mar 2011 Location: Austin, TX Posts: 279 Drives: '11 Gunmetal 370Z MT Rep Power: 16	Autospeed has quite a few aero articles related to this sort of discussion Vortex Generator 4 part series (They specifically test the vortex generators on the underside too): Vortex 1 Vortex 2 Vortex 3 Vortex 4 Also in that article they show some data from Mistu EVO tests that seems to suggest that 25mm high or so is best. Aero Testing 5 part series: Aero 1 Aero 2 Aero 3 Aero 4 Aero 5 Underflow 2 Part Series: Under car 1 Under car 2 Last edited by ChipsWithDips; 09-09-2011 at 04:36 PM.

09-09-2011, 05:40 PM	#9 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 190	thanks for the links... 1" vertical fin is the takeaway huh? if true, wonder if there's any use for those 0.45" vortex generators I bought? __________________ 2009 370Z #104 For Sale

09-09-2011, 06:59 PM	#11 (permalink)
M.Bonanni The370Z.com Sponsor Join Date: Nov 2008 Location: Las Vegas Posts: 2,575 Drives: Fast Rep Power: 1322	Awesome articles Chips! Thanks for the links! Now, if we could only find some wind tunnel photos of a stock 370Z... __________________ MikeBonanni.com Twitter: http://www.twitter.com/MikeBonanni Facebook: http://www.facebook.com/MBonanni36 Function > Form

09-09-2011, 09:15 PM	#13 (permalink)
M.Bonanni The370Z.com Sponsor Join Date: Nov 2008 Location: Las Vegas Posts: 2,575 Drives: Fast Rep Power: 1322	Just finished reading all of the links myself. Very good stuff in there. Making me re-think my front air dam now too... I do think that the Z's shape can probably get away with a shorter VG, but now I am wondering if the VGs are even going to make any positive difference at all. __________________ MikeBonanni.com Twitter: http://www.twitter.com/MikeBonanni Facebook: http://www.facebook.com/MBonanni36 Function > Form

09-09-2011, 09:44 PM	#14 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 190	even more disturbing... our car is a wing! look __________________ 2009 370Z #104 For Sale

09-09-2011, 09:52 PM	#15 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 190	I'm kidding with that last post btw! Some of my (poorly educated) theories - nissan was right to put the spoiler lip on the back... exactly because of the picture above... if they didn't there would be a lift effect of higher pressure below car vs above - my car has a rear diffuser... I actually want the air to stay "attached" on the rear deck lid and to then flow under the rear wing... it will theoretically then "re-attach" with the high speed air coming from the rear diffuser and the air coming out of the rear diff cooler box... I want all that to be as laminar as possible to minimize drag... I also want all that to hug the surface of the rear deck lid to avoid having turbulent air come in contact with the wing... that part I can be certain of... goal is to get high speed 'clean air' to the wing and keep all the turbulent air associated with roof and boundary separation 12" below the wing - therefore I need VGs at the rear roof - therefore I need VGs on the rear decklid What I don't know... do I need VGs on the front wind splitter? do I need VGs on the leading edge of the rear diffuser? __________________ 2009 370Z #104 For Sale

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