Aerodynamic Questionne

sixpax · 02-17-2014, 06:19 PM

I am wondering if two naca type ducts in the front fascia, to the right and left of the hamburger, would force the nose up a little or down a little at straightaway speeds ... not wondering about braking, the nose goes down fine under braking ... just wondering at full bore pedal to the metal going straight.

Zauskycop · 02-17-2014, 06:31 PM

Well, I would say no. Consider your spring rates on the car and how many LBS of downforce those two vents may possibly create? I doubt enough to make any difference...at worst, they may allow more air UNDER the hood and create lift!

Tracy Ramsey

Shamu · 02-17-2014, 07:50 PM

What's the hamburger?

sixpax · 02-17-2014, 08:16 PM

Quote:

Originally Posted by Shamu

What's the hamburger?

the nissan emblem on the front fascia

SouthArk370Z · 02-17-2014, 08:34 PM

Interesting question; I hope some one can come up with an authoritative answer.

Since the raison d'etre of NACA ducts is to minimize disturbances in the air flow, my guess is that they won't make much difference. But "minimize" is a rather vague term, so maybe they will make a difference at track speeds. Guessing again, if they do make a difference, it seems the added resistance at the sloped front surface would create some down force. But I'm no aerodynamics engineer. I'm just here to see if my guesses are right.

sixpax · 02-17-2014, 08:42 PM

Quote:

Originally Posted by SouthArk370Z

Interesting question; I hope some one can come up with an authoritative answer.

Since the raison d'etre of NACA ducts is to minimize disturbances in the air flow, my guess is that they won't make much difference. But "minimize" is a rather vague term, so maybe they will make a difference at track speeds. Guessing again, if they do make a difference, it seems the added resistance at the sloped front surface would create some down force. But I'm no aerodynamics engineer. I'm just here to see if my guesses are right.

Thanks for sharing ... not sure if I even have a guess one way or the other, and like you, am no aerodynamics engineer. Just curious.

sixpax · 02-17-2014, 08:44 PM

Quote:

Originally Posted by Zauskycop

Well, I would say no. Consider your spring rates on the car and how many LBS of downforce those two vents may possibly create? I doubt enough to make any difference...at worst, they may allow more air UNDER the hood and create lift!

Tracy Ramsey

Creating lift under the hood probably is not a good thing ... but would they really ?

Tazicon · 02-17-2014, 08:48 PM

I would imnagine they would create a bit of uplift. Would it be something you would actually notice is the real question.

SouthArk370Z · 02-17-2014, 08:53 PM

Quote:

Originally Posted by sixpax

Creating lift under the hood probably is not a good thing ... but would they really ?

This has been discussed before (or very similar). Someone was asking about vented/ducted hoods. I don't remember anybody coming up with a definite answer. IIRC, someone said if the bottom aero plate is installed the air exits in the tunnel and shouldn't have a big effect. If you can't find the thread (I suggest using Google and putting "site:the370z.com " in front of your search terms), I may be able to find it in my subscriptions.

BGTV8 · 02-17-2014, 08:58 PM

IMHO, this is a WOFTAM that would make three-fifth's of five-eights of f4rk-all difference.

If you want down-force, you must create negative pressure under the car, and permitting more air into the space behind the bumper is not going to facilitate negative pressure under the car - more likely to add to the pressure.

Wrong-Way, Go Back

SouthArk370Z · 02-17-2014, 10:22 PM

I asked an IRC buddy who is majoring in Aerospace Engineering and he thinks that it won't make much difference (but he's still a student, so take it with a grain of salt). He also gave me this link to a de-classified document about NACA ducts from 1945.

sixpax · 02-18-2014, 06:05 AM

Quote:

Originally Posted by SouthArk370Z

I asked an IRC buddy who is majoring in Aerospace Engineering and he thinks that it won't make much difference (but he's still a student, so take it with a grain of salt). He also gave me this link to a de-classified document about NACA ducts from 1945.

Nice. 1945 ? Surprised this was not covered in 9th grade Science class

ValidusVentus · 02-22-2014, 09:45 PM

Honestly, I think it will do two very small things aerodynamically. Add a bit of drag from disruption of airflow and air passing through the vehicle in some manner rather than over the surface of it, which is lower drag (like all openings in the front of vehicles - hence the active shutter tech we are starting to see) and probably yes, create a bit of net lift: A few hands widths back from the top leading edge of the front end (and extending backwards maybe half the hood- depending on design) is a low pressure area -taken advantage of by the draw out vents you see in the hoods of many race vehicles (the new viper GTS Rs spring to mind) these vents actively suck air through the heat exchangers at the front of the vehicle and reroute most of the air that would have to find its way out of the engine compartment by other means all while creating drag- ...reroutes it back over the vehicle and in this way also increases the airflow to the rear wing. But area in front of that is a high pressure area pushing down on the angled surface of the bumper and if you remove some of that surface area...

Both of these effects would be very minimal to the point of arbitrary in your case.

Anyway, thats my analysis and

Edit/correction: The low pressure area over the hood actually starts AT the top leading edge of most vehicles. So its entirely possible that the area you are proposing putting those ducts is a LOW pressure area

H2O_Doc · 02-22-2014, 11:30 PM

Interesting, and for once I don't feel like the nerdiest person here.

I'm sure that will change, especially if an aquatic biofilm (i.e. pond scum) thread lights up the board.

ValidusVentus · 02-26-2014, 10:24 PM

Quote:

Originally Posted by H2O_Doc

Interesting, and for once I don't feel like the nerdiest person here.

I'm sure that will change, especially if an aquatic biofilm (i.e. pond scum) thread lights up the board.

Hah dont worry, I'm a little bit of everything. Part Navy Machinist Mate (conventional), big part wannabe race car driver, part body builder/fitness hound, ...full time geek/nerd.

Are you particularly fond of pond scum?? hah

02-17-2014, 07:50 PM	#3 (permalink)
Shamu A True Z Fanatic Join Date: Jan 2011 Location: Nor Cal Posts: 1,059 Drives: 370Z Racecar Rep Power: 19	What's the hamburger? __________________ Grant

02-17-2014, 08:34 PM	#5 (permalink)
SouthArk370Z Premium Member Join Date: Nov 2010 Location: South Arkansas Posts: 8,435 Drives: 2014 Challenger Rep Power: 324198	Interesting question; I hope some one can come up with an authoritative answer. Since the raison d'etre of NACA ducts is to minimize disturbances in the air flow, my guess is that they won't make much difference. But "minimize" is a rather vague term, so maybe they will make a difference at track speeds. Guessing again, if they do make a difference, it seems the added resistance at the sloped front surface would create some down force. But I'm no aerodynamics engineer. I'm just here to see if my guesses are right. sixpax likes this. __________________ Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

02-17-2014, 08:58 PM	#10 (permalink)
BGTV8 A True Z Fanatic Join Date: Dec 2009 Location: 03350 Australia Posts: 1,514 Drives: 09 Nissan 370Z M6 Rep Power: 39973	IMHO, this is a WOFTAM that would make three-fifth's of five-eights of f4rk-all difference. If you want down-force, you must create negative pressure under the car, and permitting more air into the space behind the bumper is not going to facilitate negative pressure under the car - more likely to add to the pressure. Wrong-Way, Go Back sixpax likes this.

02-17-2014, 10:22 PM	#11 (permalink)
SouthArk370Z Premium Member Join Date: Nov 2010 Location: South Arkansas Posts: 8,435 Drives: 2014 Challenger Rep Power: 324198	I asked an IRC buddy who is majoring in Aerospace Engineering and he thinks that it won't make much difference (but he's still a student, so take it with a grain of salt). He also gave me this link to a de-classified document about NACA ducts from 1945. sixpax likes this. __________________ Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

02-22-2014, 09:45 PM	#13 (permalink)
ValidusVentus Enthusiast Member Join Date: Jun 2011 Location: Washington State Posts: 400 Drives: #18 Z34 Rep Power: 23	Honestly, I think it will do two very small things aerodynamically. Add a bit of drag from disruption of airflow and air passing through the vehicle in some manner rather than over the surface of it, which is lower drag (like all openings in the front of vehicles - hence the active shutter tech we are starting to see) and probably yes, create a bit of net lift: A few hands widths back from the top leading edge of the front end (and extending backwards maybe half the hood- depending on design) is a low pressure area -taken advantage of by the draw out vents you see in the hoods of many race vehicles (the new viper GTS Rs spring to mind) these vents actively suck air through the heat exchangers at the front of the vehicle and reroute most of the air that would have to find its way out of the engine compartment by other means all while creating drag- ...reroutes it back over the vehicle and in this way also increases the airflow to the rear wing. But area in front of that is a high pressure area pushing down on the angled surface of the bumper and if you remove some of that surface area... Both of these effects would be very minimal to the point of arbitrary in your case. Anyway, thats my analysis and Edit/correction: The low pressure area over the hood actually starts AT the top leading edge of most vehicles. So its entirely possible that the area you are proposing putting those ducts is a LOW pressure area __________________ Mods: Dedicated caged track car, lots of things. \|\|\| Valkyrie Autosport \|\|\| Last edited by ValidusVentus; 02-27-2014 at 12:11 AM.

02-17-2014, 06:31 PM	#2 (permalink)
Zauskycop Base Member Join Date: May 2011 Location: Hinckley IL Posts: 228 Drives: 2012 370Z, '16 Miata Rep Power: 14	Well, I would say no. Consider your spring rates on the car and how many LBS of downforce those two vents may possibly create? I doubt enough to make any difference...at worst, they may allow more air UNDER the hood and create lift! Tracy Ramsey

02-17-2014, 08:48 PM	#8 (permalink)
Tazicon Track Member Join Date: Mar 2012 Location: Vegas Baby! Posts: 773 Drives: German/British cars Rep Power: 14	I would imnagine they would create a bit of uplift. Would it be something you would actually notice is the real question.

02-22-2014, 11:30 PM	#14 (permalink)
H2O_Doc A True Z Fanatic Join Date: Apr 2013 Location: Northern VA Posts: 1,083 Drives: '14 370Z, '12 4Runr Rep Power: 14	Interesting, and for once I don't feel like the nerdiest person here. I'm sure that will change, especially if an aquatic biofilm (i.e. pond scum) thread lights up the board.

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