Latest Thread Images

An audiophile and petrolhead's journal: Buckle up!
Jan 20, 2013 at 8:24 PM Post #1,666 of 9,499
Quote:
billybob_jcv said:
Earlier in the thread we were talking about the SyFy channel's movies. And silly me, I recorded (and am now watching) the SyFy movie "Mongolian Death Worm". Good grief what a horrible waste of DVR drive space! It simply baffles me that someone got paid to make this turd. In contrast, this morning I watched the classic 1957 Ray Harryhausen film "20 Million Miles to Earth". Both movies contain bad acting, unrealistic monsters and little or no plot. Yet the 1957 movie is a classic example of a late 50's creature feature, and the 2010 SyFy movie is a steaming pile.


 
Click to expand...

I watched "Tasmanian Devils" yesterday....it certainly wasn't the worst SyFy movie I've seen (not that that's saying much). 
 
Jan 20, 2013 at 11:23 PM Post #1,667 of 9,499
I saw ads for "Tasmanian Devils" during the movie I watched. Your's had Apollo Ono the Olympic speed skater? Well, I guess everyone has to start somewhere. Stallone started in pron...

Back to cars, check out this place I found - it's not far from where I work. It's an excellent idea - and I'll bet they do a heck of a business in Santa Barbara - there is certainly more than enough disposable income there.
http://www.hangarsb.com/
 
Jan 20, 2013 at 11:38 PM Post #1,668 of 9,499
Quote:
billybob_jcv said:
I saw ads for "Tasmanian Devils" during the movie I watched. Your's had Apollo Ono the Olympic speed skater? Well, I guess everyone has to start somewhere. Stallone started in pron...

 
Click to expand...

Ono was there, yes....
 
but dead before the first commercial break....lol
 
Jan 22, 2013 at 12:18 AM Post #1,670 of 9,499
Perhaps one of the most beautiful sights these eyes have ever seen. :eek:





(mine has a better paint job...)


Also, what's up with the lowballing? I put some things up for sale, plainly stating that all money is going to a children's rescue home, and I get mobbed with insulting offers. It's for charity, people! Geez. :rolleyes:
 
Jan 22, 2013 at 11:43 AM Post #1,671 of 9,499
magick man said:
Perhaps one of the most beautiful sights these eyes have ever seen. :eek:





(mine has a better paint job...)
Click to expand...


:eek:

Also, what's up with the lowballing? I put some things up for sale, plainly stating that all money is going to a children's rescue home, and I get mobbed with insulting offers. It's for charity, people! Geez. :rolleyes:
Click to expand...


It's probably precisely because you said it's for charity that you're getting low-ball offers.
 
Jan 22, 2013 at 7:51 PM Post #1,673 of 9,499
Quote:
billybob_jcv said:
The only problem with that Heffner Cobra is that it no longer needs the classic Cobra hood scoop...
Click to expand...


You can always do this:
 
 

 
Can you imagine the amount of extra HP this car has just by adding those vents?
 
P.S.  I don't know who that guy on the left is.
 
Jan 22, 2013 at 8:08 PM Post #1,674 of 9,499
billybob_jcv said:
The only problem with that Heffner Cobra is that it no longer needs the classic Cobra hood scoop...
Click to expand...


We talked about that, and with proper ducting we think we could still put it to use. :wink:

Proton, you literally have no idea how many of those types of "mods" are around here. It would be hilarious if it weren't so sad.
 
Jan 22, 2013 at 10:04 PM Post #1,675 of 9,499
Quote:
magick man said:
We talked about that, and with proper ducting we think we could still put it to use.
wink.gif


Proton, you literally have no idea how many of those types of "mods" are around here. It would be hilarious if it weren't so sad.
Click to expand...


Well, I wouldn't even call it a 'mod'....its a joke. I wonder how people take these things seriously.
 
On a different note, does a hood scoop create issues with aerodynamic drag? 
As far as I know, in order to reduce the drag, the air needs to flow smoothly, and the scoop directly connects to the intake. So the engine intake limits the amount of air that can pass through. An imbalance in the input/output would increase the drag??
 
Jan 22, 2013 at 10:24 PM Post #1,676 of 9,499
Hmm... A few questions for the mechanically gifted members.
 
Today while stuck in rush hour, I noticed my clutch changing dramatically... Out of nowhere, my friction point changed and I almost stalled a few times. The clutch would start grabbing a lot sooner than "normal". Another thing to note is, the pedal was incredibly soft at rest position until you pressed it to about 1/4th. I think I may have a leak or low clutch fluid.
 
Anyone else's opinion on this?
 
Jan 22, 2013 at 11:15 PM Post #1,677 of 9,499
Yes, any disruption of the smooth shape will increase drag. The drag caused by the shape of something is called "profile drag". However, there is also a "boundary layer" close to the surface of the shape that is caused by the air flowing over the leading edge. Within the boundary layer, the viscous effects of the air are high, which means the velocity of the flow is low. Have you ever noticed that they don't bother smoothing every rivet on the outside of an big passenger airplane? That's because the boundary on a big airplane is quite large, and the those little rivets are inside that B/L, therefore they don't add much if any drag. However, there is another type of drag called "friction drag" that accounts for that same viscous effect of the air being slowed near the surface. All of the different drag components are added together to determine the overall coefficient of drag (Cd) of an object.

I don't know how tall the boundary layer is at the center of the hood of a typical car, it depends on whether the flow is laminar (smooth) or turbulent at that point, and whole bunch of other factors. You really only need to consider the part of the scoop that is sticking above the boundary layer. The "NACA duct" you see on many cars is supposed to be the optimal shape for feeding outside air into the interior of the vehicle. You'll notice it doesn't stick-up at all, thus it is entirely within the boundary layer. You still have drag due to the other factors like the viscous drag, pressure drag, etc - but it's the best you can do.



Do you recognize that one? That's on a Veyron. :p

HOWEVER - all of that is probably just unimportant nonsense, because...

The question is NOT whether the hood scoop increases drag (it does) - the question is whether it is significant. If the drag increase is small compared to the overall drag of the vehicle, then it really doesn't matter - and that's certainly the case with an AC Cobra. Those big rotating tire meats and that open top probably create much more drag than the air scoop - and feeding air efficently to the engine will generate much more horsepower than any impact of the scoop drag.

Gee - that was fun - just like the old days of my former life... :wink:
 
Jan 22, 2013 at 11:20 PM Post #1,678 of 9,499
Planx: sorry - aerodynamics I know, but mechanicals I don't... :xf_eek:

The first thing I would check is the clutch fluid level. If that looked OK, then I would scratch my head and need to call a mechanic!
 
Jan 22, 2013 at 11:44 PM Post #1,679 of 9,499
Quote:
billybob_jcv said:
Planx: sorry - aerodynamics I know, but mechanicals I don't...
redface.gif


The first thing I would check is the clutch fluid level. If that looked OK, then I would scratch my head and need to call a mechanic!
Click to expand...

 
That's why I'm scratching my head! Might be a leak where I can't see that's causing it to lose pressure and altering the properties of the clutch, or can be completely something else... Ehh..
 
Jan 23, 2013 at 12:11 AM Post #1,680 of 9,499
Quote:
billybob_jcv said:
Yes, any disruption of the smooth shape will increase drag. The drag caused by the shape of something is called "profile drag". However, there is also a "boundary layer" close to the surface of the shape that is caused by the air flowing over the leading edge. Within the boundary layer, the viscous effects of the air are high, which means the velocity of the flow is low. Have you ever noticed that they don't bother smoothing every rivet on the outside of an big passenger airplane? That's because the boundary on a big airplane is quite large, and the those little rivets are inside that B/L, therefore they don't add much if any drag. However, there is another type of drag called "friction drag" that accounts for that same viscous effect of the air being slowed near the surface. All of the different drag components are added together to determine the overall coefficient of drag (Cd) of an object.

I don't know how tall the boundary layer is at the center of the hood of a typical car, it depends on whether the flow is laminar (smooth) or turbulent at that point, and whole bunch of other factors. You really only need to consider the part of the scoop that is sticking above the boundary layer. The "NACA duct" you see on many cars is supposed to be the optimal shape for feeding outside air into the interior of the vehicle. You'll notice it doesn't stick-up at all, thus it is entirely within the boundary layer. You still have drag due to the other factors like the viscous drag, pressure drag, etc - but it's the best you can do.



Do you recognize that one? That's on a Veyron.
tongue.gif


HOWEVER - all of that is probably just unimportant nonsense, because...

The question is NOT whether the hood scoop increases drag (it does) - the question is whether it is significant. If the drag increase is small compared to the overall drag of the vehicle, then it really doesn't matter - and that's certainly the case with an AC Cobra. Those big rotating tire meats and that open top probably create much more drag than the air scoop - and feeding air efficently to the engine will generate much more horsepower than any impact of the scoop drag.

Gee - that was fun - just like the old days of my former life...
wink.gif
Click to expand...


Good explanation, that explains the design of modern sportscar vents pretty well.
 
I read in a book somewhere, a car is even more complex to design than an airplane because it works in contact with two mediums. It runs on the road, and runs in the air. Hence, its a much more complex problem to solve because you don't want a car to behave like an airplane that flies off, and still want it to go as fast as possible with minimal power.
 
For comparison, I was amazed as a kid when I saw this video (I think it was discovery channel). A small plane, with a single cylinder engine per wing, could easily overrun a 12 cylinder sportscar....
 
You must log in or register to reply here.

Users who are viewing this thread

Total: 5 (members: 0, guests: 5)
Back
Top