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Author Topic: NACA Ducts  (Read 22815 times)

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Ratliff

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NACA Ducts
« on: June 12, 2008, 07:23:48 PM »
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Ratliff

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Re: NACA Ducts
« Reply #1 on: June 12, 2008, 07:31:02 PM »
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Ratliff

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Re: NACA Ducts
« Reply #2 on: June 12, 2008, 07:43:10 PM »
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Ratliff

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Re: NACA Ducts
« Reply #3 on: June 12, 2008, 07:48:43 PM »
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Ratliff

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Re: NACA Ducts
« Reply #4 on: June 12, 2008, 08:32:35 PM »

NACA used to feed turbocharger in Honda Hawk.
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Offline Stan Back

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Re: NACA Ducts
« Reply #5 on: June 12, 2008, 10:04:09 PM »
Anything left in the library?
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Offline Stainless1

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Re: NACA Ducts
« Reply #6 on: June 12, 2008, 10:51:45 PM »
Anyone that wants to see a properly designed one just stop by our car. 

If you think you have a good one, paint it, if it is easy, then it is not working properly... Don't bother with any of the prefab ones, most don't work.

Hey Slim, I have the NACA research papers on the duct development, should I post that book here...  :evil:  I think it is only 40 or 50 pages  :-o
« Last Edit: June 12, 2008, 10:57:33 PM by Stainless1 »
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Stainless
Red Hat 228.039, 2001, 65ci, Bockscar Lakester #1000 with a little N2O

Offline jdincau

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Re: NACA Ducts
« Reply #7 on: June 12, 2008, 11:28:14 PM »
              Before we get too carried away, here is a quote from page 18 of the original NACA report,
NACA ACR No. 5120;
"Submerged inlets do not appear to have desireable pressure recovery characteristics for use in supplying air to oil coolers, radiators, or carburetors of conventional recirocating engines. "
Jim
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Unless it's crazy, ambitious and delusional, it's not worth our time!

Offline DavidinDurango

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Re: NACA Ducts
« Reply #8 on: June 13, 2008, 11:29:55 AM »
Quote from: Stainless1 on June 12, 2008, 10:51:45 PM
... Don't bother with any of the prefab ones, most don't work.


Stainless:  Why do you say that?  Is this opinion?  Do we have data?
(Please don't read attitude into this, its a question, ok?)

OK, I've opened my big mouth, its off to post my "intro" and figure a way to run a test (has anyone tested??) - I think I can get a transparent duct to wool-tuft.

Thank you.
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DavidinDurango
Mostly Fords with "some stuff"
LSR, because it takes more than one ball to play.

Offline jdincau

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Re: NACA Ducts
« Reply #9 on: June 13, 2008, 12:18:37 PM »
I will jump in here David, according to the NACA report submerged inlets must be located in an area where the flow is attached and the boundary layer is relatively thin. The slope, depth of opening and size must account for this. Putting them way aft on a flat sided vehicle makes them no better than a plain hole.
Jim
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Unless it's crazy, ambitious and delusional, it's not worth our time!

Offline Stainless1

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Re: NACA Ducts
« Reply #10 on: June 13, 2008, 12:46:22 PM »
Well, we have tried the plastic ones, didn't get any more air than with no scoop at all.  Installed the one that is on there now, it was a proven performer with a lot of development, beyond the NACA work, by Boeing.  The air box we had at that time was instrumented for pressure and showed a steady rise starting about 190 and at 220ish MPH developed almost 1 PSI at WOT.  It is on a flat sided car and mounted aft of the center.  We have had very good success with it but your luck may vary.   Proper design makes the difference.  There was a lot of work done after the NACA report by several aircraft companies.  The original posts looked like hood type designs.  The one we have came from the flat side of an airplane...
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Stainless
Red Hat 228.039, 2001, 65ci, Bockscar Lakester #1000 with a little N2O

Ratliff

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Re: NACA Ducts
« Reply #11 on: June 13, 2008, 01:04:10 PM »
http://www.landracing.com/forum/index.php/topic,4033.0.html

Other examples of how NACA ducts can be applied are shown in the thread on the Alex Tremulis design for Kitty O'Neil.

Tremulis proposed using them for engine air inlets on a jet land speed car. NACA ducts were used on the roof of the Lew Arrington rocket Funny Car to supply air that aided chute deployment.
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Offline DavidinDurango

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Re: NACA Ducts
« Reply #12 on: June 13, 2008, 01:11:05 PM »
Thank you, gentleman, for the info.  I appreciate it.
(Stainless, jdincau, and Ratliff).

I understand the boundry must be thin -obviously the duct will work better on the nose than towards the back.  good reminder!

I look forward to seeing the duct Stainless has procurred (-2 for spelling?) and how that differs from others.

best to all, keep the rubber side down.
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DavidinDurango
Mostly Fords with "some stuff"
LSR, because it takes more than one ball to play.

Offline DavidinDurango

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Re: NACA Ducts
« Reply #13 on: June 13, 2008, 01:15:19 PM »
Just to revisit the comment about plastic ducts not working . . .

My assumption is this:  the ducts would work if placed in a high pressure area, and would not work in a low pressure area/area of this boundary flow.

Am I still on the right track?

thanks again!
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DavidinDurango
Mostly Fords with "some stuff"
LSR, because it takes more than one ball to play.

Offline Vortex1

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Re: NACA Ducts
« Reply #14 on: June 13, 2008, 08:46:23 PM »
If a NACA Duct was fabricated incorrectly or placed in the wrong location on the vehicle could it pull a vacuum on the air box?




Jim B.
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