Landracing Forum
Bonneville Salt Flats Discussion => Bonneville General Chat => Topic started by: 2club on February 07, 2016, 04:25:58 AM
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No one knows what 2016 will bring in terms of salt conditions, but the Speed Demon team is wasting no time in preparing to run the new car. Here's a link to a short story about this week's wind tunnel test and what they have planned for the future. Cool video included.
http://hotrodenginetech.com/smokin-the-speed-demon/ (http://hotrodenginetech.com/smokin-the-speed-demon/)
(http://hotrodenginetech.com/wp-content/uploads/2016/02/20160203_1750271.jpg)
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Thank-you for the video and pictures. And thanks to George Poteet for allowing the world in to view the build. It gives people a great insight into what it takes to build a safe and fast record breaker.
Congratulations to George and the entire crew for a job well done. I look forward to many more positive results. :cheers: :cheers: :cheers:
Pete
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Sure beats the 3 leafblowers I aimed into a plywood tunnel for my testing! Shouldn't that cameraman have been downwind?
I sure hope they find a place to run.
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Wow, I never expected the airflow behind the cockpit to be that unstable. 0:26 to 0:35 the flow from the mid cockpit to the rear wheel well bulge is completely detached from the bodywork. I would not have expected this, the evidence is obvious. Smoke does not go randomly sideways in attached flow.
Tuft it, the degree of recirculation in the apparently "clean" areas is extreme. Some video of the rear and underside of the car with tufts would also be much more informative than blowing smoke over the front.
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I didn't think there was a way to make a concave surface "clean" when its both preceded and followed by a larger convex surface. The body shape is pretty, but it would make an unstable bullet. Wouldn't a straight profile have less overall drag? Tried and true.
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I think they are probably holding their cards close for obvious reasons on the rest of the video. Whats everyones thoughts on the "hips" of the car and the angle the body comes in afterwards? I have always wondered how the air would stay attached after the tire bulges, if it could make that corner and not seperate. I assume people smarter than me don't think it a problem or else it wouldn't be that way.
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I to would like to hear the "reasoning" for the shape of the car. As Eric (Blue) identified the air flow between the cockpit and the rear wheel covers certainly appears to be unattached. Maybe something that we are not privy to happens to the flow at the projected higher speeds that this car is targeted to run and is not observable at the lower wind tunnel speeds. I do think that they do have some level of aerodynamic expertise on staff but have never heard who it might be. More data, as Eric outlined, would be interesting but probably not going to be provided to us. It will be fun to see if the new car will be equal to the older car.
Rex
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I bet George Poteet would share the info, if he knew this thread existed, and if he was privy to the info. I'm no aerodynamic expert, but what happens inside a cylinder head should also exist outside the car, in reverse. In theory, that "waist area" in front of the hips may reduce aerodynamic drag at extreme speeds and the turbulence may "straighten out" as air has a relatively slow reaction time at 400+ mph? Instead of air impacting the hips at full velocity, it may roll away from them, at least in some small amount? Like how sometimes a bump in an intake port smooths airflow around the valve guide. At least I hope that's what they're doing.
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I'm pretty sure this will not get better with speed.
I wish they would have just tuft tested this.
As many of us that have studied Aerodynamics understand, the Speed Demon is not optimal but apparently it's good enough. No car is optimal. I know the Carbiliner can be improved.
The body of the Speed Demon is an evolution. I believe the car was stretched in the "waste" area. I don't think the body was ever designed from scratch.
It would have been neat to see what design they would have come up with if they started from scratch. A huge part of building these cars is building the body. Since the molds were already made, it made sense to just rebuild the car and not design from scratch. Changes can easily be made to fix the stability problem and the car is one of the most successful if not the most successful car in the wheel driven LSR game.
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I wonder how the turbo air inlets enter into the equation
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I seem to remember a conversation between George & Al that the design was conceived over dinner at the StateLine & drawn up on a napkin.
Sid.
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The guy that does my aero is more qualified than most on the forum
and called the previous car "iffy''.
If NASA has designed that one or the current one they wouldn't look
the way they do.
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Speed Demon is an evolution of Ron Main,s original Flat Fire lakester.
DW
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I'm sure Speed Demon's aerodynamic "faults" are tradeoffs to get down force .
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I'm sure Speed Demon's aerodynamic "faults" are tradeoffs to get down force .
Yes but what are talking about here does not help down force. In the grand scheme of things it will probably not mean much. We're just nit picking as there is nothing else to talk about.
I think Steve and his crew has done a great job of getting a great car back together again!
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If we have a race course next year I am sure that we will find out if the new car has the same or better performance than the old. As we all know George knows what to do with the pedal on the right!
Rex
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I didn't think there was a way to make a concave surface "clean" when its both preceded and followed by a larger convex surface. The body shape is pretty, but it would make an unstable bullet. Wouldn't a straight profile have less overall drag? Tried and true.
It's funny that you mentioned "tried and true". This car shape has more runs over 400 than all others put together. I'm sure they call this "tried and true."
Also, can you please share the data showing that straight profiles have less drag?
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"Drag" is also your friend, :wink:
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The shape of this car looks like they may have considered "area rule" in the design. :?
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The shape of this car looks like they may have considered "area rule" in the design. :?
How do you figure?
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Are any considerations given to the effect of exhaust affecting airflow around tail ?
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Ub, if you could sit here and look over "there" on the wall you'd see the photo that I got from Pork Pie a few years ago. It shows the Speed Demon chugging along at flank speed -- the 450+ run, if I remember correctly - and you can see without a shred of doubt the exhaust plume. The exhaust escaped near the centerline of the car and no doubt fiddled around with the aero of the tail.
And if it's plain to me, sitting here in a snowstorm, then I would guess that the Speed Demon team knows it was there on the old car and used that information -- maybe even more refined than my armchair observation) to decide how to build the new one -- which has exhaust outlets much farther outboard on either side of the top surface - and before the tail. I've got photos but they're at work. If any of youse guys have a current photo -- from the GNRS, for instance - please post 'em. Thanks.
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The shape of this car looks like they may have considered "area rule" in the design. :?
How do you figure?
When I was working on the B1-B program, I got to know several of the engineers who had been involved in the original design, as well as the XB70 before it. I asked them how the shape of the aircraft came about because I was pretty curious about it, and they took the time to give me a short hand explanation of area rule. The characteristic "wasp waist" or "coke bottle" shape of a lot of aircraft designed around that time is the most visible clue that it was factored into the design, but even today it is used, it's just not as visible to the untrained eye.
I went looking for a better explanation than I can give, since I can't even claim a rudimentary grasp of the subject, and found this. It seems to outline it pretty well. Note that area rule is specifically effective assisting in the control of shock waves in the higher subsonic and trans-sonic regimes, starting somewhere around the 500 MPH range. (Familiar number, huh?)
https://en.wikipedia.org/wiki/Area_rule
The change in profile from the driver's compartment area, through the engine compartment, and to the drive wheels, looks like it may follow this rule to some extent, is all I was saying. The speeds they are looking for may well be in the range where it can be effective.
Really it's just a W.A.G. on my part, but it looks almost plausible. :-D
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The reason for area ruling is to take into consideration of the area of the wings so that total cross sectional area grows and shrinks uniformly and smoothly. This car has no wings. Therefore there's no reason to neck the body down behind drivers compartment. There are no wings to compensate for.
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For those interested.....
https://www.youtube.com/watch?v=Cn0lSoreB1g
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Are they designing the body to provide drag at the rear where it is far behind the center of gravity? This might give it more resistance to going sideways under power.
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Any thoughts on how the dorsal exhaust outlets will effect airflow over rear afterbody,stabilizer ? Pete
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The reason for area ruling is to take into consideration of the area of the wings so that total cross sectional area grows and shrinks uniformly and smoothly. This car has no wings. Therefore there's no reason to neck the body down behind drivers compartment. There are no wings to compensate for.
As I understood it, the purpose is to minimize total cross sectional area change, and to control where on the vehicle this change occurs in order to limit the effects of the shock waves, or possibly take some sort of advantage of them.
On an airplane the wings are sort of necessary, and obviously must be accounted for in area rule design. I don't see how it would necessarily follow that just because a vehicle doesn't have wings the basic tenets wouldn't still apply.
Like I said, I'm no how no way an expert, and it was just a W.A.G. on my part. 8-)
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As mentioned above the area rule came about when they were trying to understand why there were huge changes in drag as an aircraft entered the transonic speed range (ie some local air flow might be very close to going super sonic even though the overall aircraft was still below supersonic speeds).
This was finally validated in the design of the F-102A aircraft, the original design F-102 could not achieve supersonic speeds but after shifting to an area ruled design they reduced drag by approximately 25% at transonic speeds and the new A version easily went supersonic.
Again this really only applies at near supersonic speeds (about 0.7 mach or about 500 mph) when certain areas on the body might force the airstream to accelerate to high subsonic speeds and incompressable flow has trouble getting out of the way of the car.
One other consideration, is that boundary layer thickness builds as the air moves down the body, creating an effectively larger and larger car body as the air must move around not only the car body but also this thickend boundary layer. One way to re-attach flow is to put a bulging section in the body to create a favorable pressure gradient (ie increasing pressure as you move down the body) and this can allow the detached flow to re-attach to the surface.
Without knowing the specific design considerations in that body shape it is just speculation but that rear bulge would also help move the center of pressure to the rear from where it would be on a uniform body. Like the skirt on a pellet gun pellet (or a badminton shuttle cock) moves the center of pressure well behind the nose to make it more stable.
http://history.nasa.gov/SP-4219/Chapter5.html
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The reason for area ruling is to take into consideration of the area of the wings so that total cross sectional area grows and shrinks uniformly and smoothly. This car has no wings. Therefore there's no reason to neck the body down behind drivers compartment. There are no wings to compensate for.
As I understood it, the purpose is to minimize total cross sectional area change, and to control where on the vehicle this change occurs in order to limit the effects of the shock waves, or possibly take some sort of advantage of them.
On an airplane the wings are sort of necessary, and obviously must be accounted for in area rule design. I don't see how it would necessarily follow that just because a vehicle doesn't have wings the basic tenets wouldn't still apply.
Like I said, I'm no how no way an expert, and it was just a W.A.G. on my part. 8-)
Hi Wizzbang,
First off, if I sounded short with you on any of my post, I apologize. Somethings my fingers don't put down in writing in the same tone as my brain.
As I understand it, when area ruling a body whether a plane or car, you want the growth and shrinkage of the total cross sectional area to be smooth with no lumps. High spot of the cross sectional area including appendages should be somewhere near the center or slightly aft. I only say slightly aft because you must include jet or rocket plume in your modeling. There should not be two or more high spots as in coke bottle design. I'm pretty sure this will increase drag.
Imagine if you have a airplane and you slice it up lengthwise into 6" segments. You next measure the cross section of each of those segments and record them from front to back. Then you layout these numbers on a graph. You will quickly see if you have a problem. From here you can adjust the model if possible to improve the graph or just plug the "smoothness" into the equation that is needed to calculate "wave drag".
Now, to make matters more complicated the above mentioned method can only be used to calculate wave drag at Mach 1.0 Coming up with graph to calculate wave drag (the majority of your drag in a supersonic car) let's say Mach 1.5, these cross sectional area need to be calculated in swept back cones from the centerline of the body. The higher number you want to calculate for, the sharper the cones will need to be. Eric (Blue) knows or knows where to find the the angle of the cones for a given Mach number.
Eric has been a good and patient teacher to me and Eric if I have said anything that is wrong or inaccurate, please correct me.
Eric is a good teacher because he does not let me take his word for anything. He makes me read the text from where he has learned it.
What I'm also trying to say in this long winded text is that if the designers of the Speed Demon were trying area rule this shape, they messed up. I'm pretty sure they were not.
Off the subject slightly, there are a few high end Ultimate (supersonic) car designers have a theory that it is totally impractical to build an Area Ruled LSR car. I was lucky enough to be able to help Eric prove that theory incorrect. This car is area ruled to Mach 1.5.
(http://images.tapatalk-cdn.com/16/02/14/92578c9f404e0aeed51fc3b5010668b4.jpg)(http://images.tapatalk-cdn.com/16/02/14/e57c1a733fb429350f2f99b2c4acc439.jpg)
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Thanks to 7800ebs for posting video! It's a good one.
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The reason for area ruling is to take into consideration of the area of the wings so that total cross sectional area grows and shrinks uniformly and smoothly. This car has no wings. Therefore there's no reason to neck the body down behind drivers compartment. There are no wings to compensate for.
As I understood it, the purpose is to minimize total cross sectional area change, and to control where on the vehicle this change occurs in order to limit the effects of the shock waves, or possibly take some sort of advantage of them.
On an airplane the wings are sort of necessary, and obviously must be accounted for in area rule design. I don't see how it would necessarily follow that just because a vehicle doesn't have wings the basic tenets wouldn't still apply.
Like I said, I'm no how no way an expert, and it was just a W.A.G. on my part. 8-)
Hi Wizzbang,
First off, if I sounded short with you on any of my post, I apologize. Somethings my fingers don't put down in writing in the same tone as my brain.
As I understand it, when area ruling a body whether a plane or car, you want the growth and shrinkage of the total cross sectional area to be smooth with no lumps. High spot of the cross sectional area including appendages should be somewhere near the center or slightly aft. I only say slightly aft because you must include jet or rocket plume in your modeling. There should not be two or more high spots as in coke bottle design. I'm pretty sure this will increase drag.
Imagine if you have a airplane and you slice it up lengthwise into 6" segments. You next measure the cross section of each of those segments and record them from front to back. Then you layout these numbers on a graph. You will quickly see if you have a problem. From here you can adjust the model if possible to improve the graph or just plug the "smoothness" into the equation that is needed to calculate "wave drag".
Now, to make matters more complicated the above mentioned method can only be used to calculate wave drag at Mach 1.0 Coming up with graph to calculate wave drag (the majority of your drag in a supersonic car) let's say Mach 1.5, these cross sectional area need to be calculated in swept back cones from the centerline of the body. The higher number you want to calculate for, the sharper the cones will need to be. Eric (Blue) knows or knows where to find the the angle of the cones for a given Mach number.
Eric has been a good and patient teacher to me and Eric if I have said anything that is wrong or inaccurate, please correct me.
Eric is a good teacher because he does not let me take his word for anything. He makes me read the text from where he has learned it.
What I'm also trying to say in this long winded text is that if the designers of the Speed Demon were trying area rule this shape, they messed up. I'm pretty sure they were not.
Off the subject slightly, there are a few high end Ultimate (supersonic) car designers have a theory that it is totally impractical to build an Area Ruled LSR car. I was lucky enough to be able to help Eric prove that theory incorrect. This car is area ruled to Mach 1.5.
(http://images.tapatalk-cdn.com/16/02/14/92578c9f404e0aeed51fc3b5010668b4.jpg)(http://images.tapatalk-cdn.com/16/02/14/e57c1a733fb429350f2f99b2c4acc439.jpg)
No offense taken, or implied. :-D I'm just enjoying engaging in a conversation on a subject that interests me, but is way over my head in actuality. 8-)
I can see that the Speed Demon design isn't optimized for lowest possible drag, and that makes sense, since it has to be a compromise that takes into consideration a whole raft of conflicting issues. What I thought I saw a possibility of was that they were using the basic principles to induce and manipulate shock waves to their benefit at the speeds they are targeting. It looks to me like the air will accelerate in the area behind the cockpit, and then encounter the flared wheel area, possibly forming a shock wave at the rear of the vehicle and inducing stability enhancing drag behind the CG at target speed without having to push a larger tail fin through the air while getting up to that speed, thus helping with acceleration.
Like I said, just blowing smoke and making Wild A** Guesses. :cheers:
Eric's design looks awesome. Someone needs to really hit the Lotto and finance that. :cheers:
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Hotrod, great info thanks for posting!
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Speaking of the SD wind tunnel test, Layne Christensen of the Darko Tunnel called yesterday and we're going to put the latest video of the new #715 car in the tunnel -- just last week or so. I'll get it as soon as I can. I hear it's over on Mike Cook's FB page, so you might have already seen it. I'll put it here ASAP.
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http://hotrodenginetech.com/smokin-the-speed-demon/ (http://hotrodenginetech.com/smokin-the-speed-demon/) :cheers:
Mike
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The reason for area ruling is to take into consideration of the area of the wings so that total cross sectional area grows and shrinks uniformly and smoothly. This car has no wings. Therefore there's no reason to neck the body down behind drivers compartment. There are no wings to compensate for.
As I understood it, the purpose is to minimize total cross sectional area change, and to control where on the vehicle this change occurs in order to limit the effects of the shock waves, or possibly take some sort of advantage of them.
On an airplane the wings are sort of necessary, and obviously must be accounted for in area rule design. I don't see how it would necessarily follow that just because a vehicle doesn't have wings the basic tenets wouldn't still apply.
Like I said, I'm no how no way an expert, and it was just a W.A.G. on my part. 8-)
Hi Wizzbang,
First off, if I sounded short with you on any of my post, I apologize. Somethings my fingers don't put down in writing in the same tone as my brain.
As I understand it, when area ruling a body whether a plane or car, you want the growth and shrinkage of the total cross sectional area to be smooth with no lumps. High spot of the cross sectional area including appendages should be somewhere near the center or slightly aft. I only say slightly aft because you must include jet or rocket plume in your modeling. There should not be two or more high spots as in coke bottle design. I'm pretty sure this will increase drag.
Imagine if you have a airplane and you slice it up lengthwise into 6" segments. You next measure the cross section of each of those segments and record them from front to back. Then you layout these numbers on a graph. You will quickly see if you have a problem. From here you can adjust the model if possible to improve the graph or just plug the "smoothness" into the equation that is needed to calculate "wave drag".
Now, to make matters more complicated the above mentioned method can only be used to calculate wave drag at Mach 1.0 Coming up with graph to calculate wave drag (the majority of your drag in a supersonic car) let's say Mach 1.5, these cross sectional area need to be calculated in swept back cones from the centerline of the body. The higher number you want to calculate for, the sharper the cones will need to be. Eric (Blue) knows or knows where to find the the angle of the cones for a given Mach number.
Eric has been a good and patient teacher to me and Eric if I have said anything that is wrong or inaccurate, please correct me.
Eric is a good teacher because he does not let me take his word for anything. He makes me read the text from where he has learned it.
What I'm also trying to say in this long winded text is that if the designers of the Speed Demon were trying area rule this shape, they messed up. I'm pretty sure they were not.
Off the subject slightly, there are a few high end Ultimate (supersonic) car designers have a theory that it is totally impractical to build an Area Ruled LSR car. I was lucky enough to be able to help Eric prove that theory incorrect. This car is area ruled to Mach 1.5.
(http://images.tapatalk-cdn.com/16/02/14/92578c9f404e0aeed51fc3b5010668b4.jpg)(http://images.tapatalk-cdn.com/16/02/14/e57c1a733fb429350f2f99b2c4acc439.jpg)
Rob, everything you have said is correct. Please post the M1.5 volume distribution graphic, plot, and USAFA shock distribution. The surface porosity vs. Mach data may be requested by other teams, we will publish if and when a credible attempt on the ALSR is mounted.
So far there isn't one.
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"Drag" is also your friend, :wink:
never.
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"Drag" is also your friend, :wink:
never.
"never", in relation to :? :?
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"Drag" is also your friend, :wink:
never.
"never", in relation to :? :?
OK, I'll modify that. Drag is our friend when we want to slow down, not when we want to go fast.
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Without drag there will never be a CP.
Sid
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with stablity, we go faster,,
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Yes and no.
All cars will have a certain amount of drag. The key is to have drag increase on the rear as well as air deflection as soon as yaw starts.
A small parachute hanging from the back of the car might keep it straight but that would be a terrible way to achieve what what we are looking for.
Btw, the aero drag that give you stability also gives you instability if it is on the wrong end of the car.
We could build a car that is stable that could run in a vacuum (assuming we had onboard oxygen for engine). Space craft do it all the time.
But I regress. The reason for the vertical fins that we use is that as soon as any yaw is encountered, it starts to redirect air like a wing in an angle of attack. The displacement of that air is what tries to straighten up the car keeping it stable. We never want to increase drag at the rear of the car, we want to manipulate the air to make the car stable.
I can't think of any instances where drag is good.
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Without drag there will never be a CP.
Sid
There is a fundamental difference between forces and moments. Cp (as is used in LSR) is a function of moment in yaw, drag is a separate force.
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Like many on this forum, I'm always willing to learn. Can you explain that?
Sid.
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Mr. Blue,
In my little handbook of airfoil sections, Cp is the reference for Center of Pressure for the airfoil.
Did I miss something in the language of transformation for aero structures and references?
Thanx in advance,
HB2 :-)
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I was standing about 5 ft. from Ron Main as he was expounding on the lack of correct info on aero as it applies to objects travailing at high speed next to the ground. I was in the Speed Demon pit as they were performing an engine change. Ron uses some very colorful language that makes for a good listen. I heard him proclaim that people were using obsolete info in there areo understanding as it applies to LSR. It seems that short of winning the Lotto the best thing a person of limited means could do is to copy the design of Nebulous, Poteet, Eric or even a car with the exhaust routed down the sides. Jack says his cars go under the air. Who can argue with any of these guys results? Unless your name is Rex just be a copy cat and get building....
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Not really sure how to take that comment: "Unless your name is Rex just be a copy cat and get building...." but I will take it as a complement! Actually there is quite a bit of data regarding aero objects moving close to the ground you just have to find them and then see how they apply to what ever you are working on. The laws of physics i.e. aerodynamics, apply to everyone and everywhere you just have to figure out which ones and how they pertain to your specific project.
Flat bottom cars are built because they are much easier to build than a round bottom car, more room for "stuff" and you only need to build half of the body!
Rex
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I think that was a compliment. :cheers:
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Imagine how much faster the Nebulous cars would go if they just had a round bottom!
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Yeah. Just think. :roll:
Wayno
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What is the shape of the worlds fastest wheel driven car? (503 mph) Hint, not flat bottom.
Rex
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What is the horsepower difference between Turbinator and Neb 3? How fast would Neb 3 go with that kind of power? Can we extrapolate comparative efficiency by comparing speed and power?
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I expect you'll run into trouble following that line of wondering, Rich. If nothing else -- the 2WD/4WD difference makes projecting even more difficult (or so I should think).
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It is my not so humble opinion that fighting over who has the best aero (from a drag perspective) is a waste of time and this includes flat or round bottoms. All of these cars have very low drag. The key to 400 plus cars going fast is how well the car works. Can the driver stay on the gas? Does the car hook up? Aero stability is more important than aero drag. I have run the numbers on my car over and over. I benefit more from a weight loss than any conceivable amount of drag reduction. I could spend more money than I will ever have and probably not make enough of a drag reduction to make a "significant" amount of extra speed. If you look at the speeds of Jack's car and my car this year, There is no doubt that cars are going faster on less power than ever. And our cars are drastically different. My platform was built with bigger engines in mind down the road with much more hp.
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I expect you'll run into trouble following that line of wondering, Rich. If nothing else -- the 2WD/4WD difference makes projecting even more difficult (or so I should think).
And that was my point. I didn't read the previous part of the thread, so I am not really sure about what it is I am commenting on. But it seemed that the reference to the Nebulous 3 car and Turbinator was apples to oranges.
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I haven't researched but didn't George go faster in the old car?.
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The other side is of course the Flashpoint guys did qualify at over 450 at WOS and that is the most slab sided, flat bottomed car around that is until they knocked all of the corners off of it! Rick Yacoucci is real close to 400 with his E blown fuel motor in one of Jacks cars and Eddy is so right about aero stability and weight. That is the great thing about racing at Bonneville, so many answers to the question of "How do I go fast?" I also think that the Vesco car probably has the most horse power and it's engine is a much better design to provide high horse power over sustained amounts of time.
Rex
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To Chop shops point
When you start trying to go the speeds they are in its about Drag TE, Time and how much weight you are trying to MOVE to a higher speed
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As usual Rex has summed everything up in one paragraph. Now we can move on. :lol: By the way, for reasons that Rex mentioned previously, streamliners are often compromised by packaging and trailer length considerations.When I started coming to Bonneville there were 3 fast cars. Nolan White, Al Teig and Tom Burkland. Now there are many and more in the works. So much diversity, unreal and cool. No cookie cutters in LSR.
In all seriousness, there is one special construction category car that is no compromise. It is round with no bubble for a roll cage, it is not unnecessarily long,with axle fairings and as narrow of tires as possible I cannot see how it could be improved upon. It has got to have the lowest CD and frontal area that an open wheel car can achieve. Considering who owns it what would you expect. :cheers:
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As usual Rex has summed everything up in one paragraph. Now we can move on. :lol: By the way, for reasons that Rex mentioned previously, streamliners are often compromised by packaging and trailer length considerations.When I started coming to Bonneville there were 3 fast cars. Nolan White, Al Teig and Tom Burkland. Now there are many and more in the works. So much diversity, unreal and cool. No cookie cutters in LSR.
In all seriousness, there is one special construction category car that is no compromise. It is round with no bubble for a roll cage, it is not unnecessarily long,with axle fairings and as narrow of tires as possible I cannot see how it could be improved upon. It has got to have the lowest CD and frontal area that an open wheel car can achieve. Considering who owns it what would you expect. :cheers:
:-D :-D :-D :-D :-D :cheers:
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Oh, Rex, I'm not one to correct anyone on this site. BUT Yacoucci is running GAS. Are you kidding me. 409 exit on gas? E class. What will they think of next. I doubt if Jack thought one of his cars would ever go 400. I listened to an interview Rick gave at SEMA and I think he has the bug to run some big numbers. :evil: :evil:
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Cars are not my expertise so do not take these comments too seriously. It seems a flat bottomed vehicle designed to be stable with limited bottom to ground clearance might work well in those conditions. Going over a bump on the salt at speed, where the front of the car rises and takes a big gulp of air under the vehicle, might lead to unanticipated stability issues.
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I have a trophy from 2000 when we ran my Nissan engine in the 788 car. We set records at Muroc and El Mirage in 99. The car had been running for several years by then. And it was preceded by the very similar NT2 car that Rick drove to 368 I think. Later Jim and Mary True would set several records in that car. Jack had been well over 300 in NT3 with Al Liest's 300 inch SBC years before he ran my Nissan. All together they may have 1000 runs on NT2 and 3. Anyone who thinks they don't work or will crash must not be paying attention.
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I was just going to mention Jacks trademark 10" wide ten ft. long nose. Not much change of catching air on the famous salt "jumps". I think you (Rich) have summed up the numbers nicely :-D Rick also has more seat time then nearly anyone currently racing. I doubt he would think there was more speed in the design if he was noticing high speed instability. Worst case, LEAD
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The new HOT ROD (May) has an excellent article on Poteet's LS based Dart head and block engine. It details ever aspect of the engine including spec, clearance and manufactures. Also discloses the problems they found the fix for. Anyone with just a couple hundred thousand $ could take the info in this story and easily replicate the results. I literally can't believe the detailed info for anyone that can read. Kenny Duttweiler, the Rembrandt of land speed :lol:
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The new HOT ROD (May) has an excellent article on Poteet's LS based Dart head and block engine. It details ever aspect of the engine including spec, clearance and manufactures. Also discloses the problems they found the fix for. Anyone with just a couple hundred thousand $ could take the info in this story and easily replicate the results. I literally can't believe the detailed info for anyone that can read. Kenny Duttweiler, the Rembrandt of land speed :lol:
Hi Racergeo,
I'm not trying to upset anybody with this post, I'm just trying to inject a bit of reality about the process of "building racing engines". Racing engines are, for the most part, simple and reliable lumps of machinery. But they are "sensitive" to certain conditions, and respond poorly to some types of "abuse".
IMO, and I've been doing this a long time, there is little to no danger to the efforts of Mr. Poteet, Mr. Main, or Mr. Duttweiler in this situation. "Revealing your secrets" in a magazine article, is a far cry from "coherent duplication". The article may provide a reasonable "road map" for other "professionals", but does little for the average "enthusiast", except to provide fodder for bar room "discussion".
My reasoning is thus:
A/ "Anyone with a couple of hundred thousand dollars . . ." Possession of the parts, does not predicate knowledge of the "complete" process . . . .
2/ Magazine articles of this nature typically are "incomplete". I have never seen an article where "every last detail" was printed . . . . . and trust me, much is left out.
d/ Readers do NOT get: Mr. Duttweiler's experience or work ethic from the magazine article. The ability of "consummate professionals" is often under-rated, IMHO . . . . .
And finally:
A statement I have heard often is: "I can build an engine as good as anybody." To which my response (on a diplomatic day) might be: "Well, uhhmm, NO, you can't."
My reasons:
1/ Enthusiast built engines, seldom achieve target bhp. Various reasons for these "phenomena", but most often it is lack of attention to details, such as:
a/ Unrealistic expectations (this could be a book . . . .)
b/ Properly timing the cam(s)
c/ Properly calculating compression ratio
d/ Properly measuring clearances
e/ Properly tensioning fasteners
f/ Lack of investment in the actual time required to perform a task properly (ie: rush job)
2/ Lack of proper tools for the above, lack of tool maintenance, lack of tool certification, improper use of these tools . . . . .
3/ Wrong attitude about the actual responsibility of checking every last detail of the assembly.
I could go on and on, but I'll spare everyone and stop by saying this: After "enthusiast built" engines perform poorly on the dyno, the company I work for gets hired to fix them.
:cheers: :dhorse: :cheers:
Fordboy
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Jeez, fordboy289 :evil:, Thanks for for your insightful response to my totally "tongue in cheek" post so that Tom "DeSoto Man" and several others that have let their Hot Rod lapse can be informed. He and many on this site that are closet millionaires have been waiting for the very info in that article to make their move. :-D I for one have already calibrated my Harbor Freight plastic dial caliper with my 1" rebar. I ordered a new sleeve of Plastigauge and of course got out my 180 grit ball hone. :wink: I totally understand where you're coming from, in that Kenny has built such a de-tuned engine that the expectation of realizing 2600 Hp is effortless. :lol:
So tell me what gave you the idea I was addressing "average enthusiasts" on this site? Name one average person. I for one would like to attain average, but have been BELOW so long I'm just used to it. :cheers:
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Wherever I am- closet millionaire or closet pauper, above or below average enthusiast- I found the Speed Demon article as interesting as anything I've read in Hot Rod in the last fifty years. :roll:
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9 pages of photos and descriptions by HOT ROD'S best technical writer, Marlan Davis. Ya, Jack I agree with you. :-)Fun to read what George has up his sleeve, like an extra 30 mph.
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Jeez, fordboy289 :evil:, Thanks for for your insightful response to my totally "tongue in cheek" post so that Tom "DeSoto Man" and several others that have let their Hot Rod lapse can be informed. He and many on this site that are closet millionaires have been waiting for the very info in that article to make their move. :-D I for one have already calibrated my Harbor Freight plastic dial caliper with my 1" rebar. I ordered a new sleeve of Plastigauge and of course got out my 180 grit ball hone. :wink: I totally understand where you're coming from, in that Kenny has built such a de-tuned engine that the expectation of realizing 2600 Hp is effortless. :lol:
So tell me what gave you the idea I was addressing "average enthusiasts" on this site? Name one average person. I for one would like to attain average, but have been BELOW so long I'm just used to it. :cheers:
Wherever I am- closet millionaire or closet pauper, above or below average enthusiast- I found the Speed Demon article as interesting as anything I've read in Hot Rod in the last fifty years. :roll:
9 pages of photos and descriptions by HOT ROD'S best technical writer, Marlan Davis. Ya, Jack I agree with you. :-)Fun to read what George has up his sleeve, like an extra 30 mph.
The new HOT ROD (May) has an excellent article on Poteet's LS based Dart head and block engine. It details ever aspect of the engine including spec, clearance and manufactures. Also discloses the problems they found the fix for. Anyone with just a couple hundred thousand $ could take the info in this story and easily replicate the results. I literally can't believe the detailed info for anyone that can read. Kenny Duttweiler, the Rembrandt of land speed :lol:
Hi Racergeo,
I'm not trying to upset anybody with this post, I'm just trying to inject a bit of reality about the process of "building racing engines".
:cheers: :dhorse: :cheers:
Fordboy
Hi again Racergeo,
My apologies for addressing my post to you. You personally, were not the focus of my post, I was trying to address, poorly done, (my bad), non-posting members and what the owner and moderators label "lurkers", ie, those who glean the board for ideas and information, yet will not sign up or contribute.
However, members of this forum, in spite of what each of them thinks of themselves, are NOT equals. Consider that for a moment. And let me make some points:
NOT equal in finances
NOT equal in work ethic or time allotted for completion
NOT equal engineering ability or execution
NOT equal in machining ability
NOT equal in fabricating ability
NOT equal in welding ability
I could go on, but I won't. I don't consider this a "bad" thing. Members can learn from other member's "skill sets", and the "idea exchange" is helpful at all levels. Kudos to any member who is willing to allow every other member, and lurkers, to view their experience, and gain from that what they can. I wish I had Jack G's machining skills and Peter J's welding skills, and I could go on with this list too.
So my opinion is that the most important difference about members of this forum is those that spend time posting Vs. those who do not. When you peruse the membership list, you will notice that most members DO NOT post anything. This does not begin to consider the "lurkers". So members who post, set themselves above average by being engaged in the process of attempting to spread their information and knowledge. These are NOT the folks my comments were intended for. My comments were intended for the much larger audience of "non-contributors", you know the ones, the "I can build an engine as good as anybody" crowd.
It is quite likely that I have become cranky as I have aged, but I give no apology for that, in the same way that the foolhardy give no apology for being "stupidy". But any members here who felt I directed my comments at them, I sincerely apologize.
I'm just at the end of my run, and I'm "disappointed", and cranky! So I'll restrain myself from commenting on these topics in the future. You'll be able to find me on the river, out fishing.
:dhorse: :cheers: :dhorse:
Crankyboy
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Tom "DeSoto Man" and several others that have let their Hot Rod lapse can be informed. He and many on this site that are closet millionaires have been waiting for the very info in that article to make their move.
George, Where was that closet that I have all those millions in? Since you posted that on here, I have tore every closet I have apart looking for that money. I am so tired right now as I have not had time to sleep I have been so busy. I did find some things I forgot I had though so it was not a total loss. I found my old Greeves Jersey, leathers, and MX Boots from 45 years ago. So that was good. :-D
I wish I would have found that money though, as I would have been able to call Marlo up and talk turkey, and even get your car fixed for you. 8-)
PS. I still do get Hot Rod and yes George's new motor is very nice and the article was good, I was more impressed with the article on page 54 about Mike Moran Twin Turbo billet Hemi, JMO, but I like spark plugs in the center of the valve cover. :cheers:
Fordboy says:
I'm just at the end of my run, and I'm "disappointed", and cranky! So I'll restrain myself from commenting on these topics in the future. You'll be able to find me on the river, out fishing.
Let me know where that fishing hole is and I will join you. But until then keep on posting as we will have plenty of time for fishing in the future. :cheers:
Tom G.
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Tom, I'll take you off my 'Go Fund Me" list as you hid that stash to well. Try under the mattress just one more time. I have followed Mike Moran in the pages of Hot Rod for years, and everything he builds is over the top. One error I noted in the photos was that of the picture of his huge 4.75 piston along side a piston identified as a 4" 5.0 Ford unit. However the valve relief notches are for a OHC 4 valve engine. They come up with 5.0 with a smaller bore and longer stroke which would explain why the hemi piston looks so Huge. Pretty crazy, 12.5 compression and then throw 70psi of boost at it. I wonder if it would last for a minute on the salt with 1600 pounds of valve spring pressure. :-o
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my take after reading both articles: both of those engs are both way, way up there trying to develop the most --one that will live and fit in tight confines as well a make big HP
The second has no limits
I think I may have picked up some ideas on what my be causing my semi-low bucks engs to fail
I have gained insights to performance engs several times over the years by phrases used in like articles
Even with KD knowlwdge base-- the amount of time he must have spent developing this package was BUNCHE$
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Anybody here familiar with the Total Seal square-section O-rings Speed Demon will use? I'm wondering whether they are intended to use receiver grooves in the heads or not? In the only photo showing the head deck, no receiver grooves are visible, but the text mentions "grooves in block and heads".
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Jack, the tech folks at Rocket Seals might be a big help. Something I was working on had one of those O-rings and I got a replacement from them.
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Disregard the previous post. The Rocket Seals square o-ring was rubber. This morning I read the Hot Rod articles about big motors. That is quite impressive. It make sense for Duttweiler and others to give out this info from a business viewpoint. Folks need to know about the things they do and sell in order to buy their services and parts.
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Just wondering what some of you that posted on this topic think after the result George and Speed Demon had at last years Speed Week. Aero must be petty good, two wheel drive not the worst and single non hemi engine. I know that He has a Liberty 10 speed trans on order and Craig Liberty is doing the engineering for it right now. That's right TEN SPEED. Clearly George is trying to get another quarter mile or so in top gear to take the absolute wheel driven record. :-)
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MY LIMITED UNDERSTANDING OF HOW TO GO REALLY FAST IN A LIMITED DISTANCE ( 5 MILES ) HAS A LOT TO DO WITH TRACTION IN THE FIRST SEVERAL MILES RELATING TO SPEED IN THE REMAINING DISTANCE .. IF YOU NEVER CAN REALLY HOOK DOWN , THAN YOUR SPEED WILL REFLECT THE RESULT .. ME , I ONLY WILL RUN ABOUT 120 MPH THIS YEAR , SO TRACTION NOT MY ISSUE , EVERYTHING ELSE IS !! I AM SOOO
LOOKING FORWARD TO THIS YEAR .. EVERYTHING IS APART TO MAKE IT AS GOOD AS IT CAN BE ANY NOT HURT ITSELF .. EVERY FALL I THINK I WILL UP GRADE A FEW THINGS HA HA , ITS ALWAYS MORE . NEW WIRING SO WILL START AND RUN , ENGINE APART , CHECK EVERYTHING , WHAT CAN I MAKE A ITTLE BETTER .. BOOOST WILL STAY AT 6 / 7 LBS. ,, GASOLINE , CAM TIMING HAS BEEN A BIG AWAKENING , 90 DEGREES ABDC FOR INTAKE SEATING , SURE WOKE UP TOP END !! I WILL SEEE .. I KNOW LOTS OF RACERS ARE DOING THE SAME THING .. STEVE
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Why are you shouting?
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Clearly George is trying to get another quarter mile or so in top gear to take the absolute wheel driven record. :-)
I'll bet what he's really after is a wheel-driven record at (or above) 500!
Jeff in Boise
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The addition of more gears will certainly help keep the engine in the needed power band to get more top end. But while that area is going to be changed the next issue then will become more of a concern that's traction. Oh the fun of trying to go even faster its an endless addiction for sure.
Ronnieroadster
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With a significantly less-massive car, getting more traction will require aerodynamic methods. I wonder whether
the Speed Demon team has consulted with the Carbinite team, who appears to be pretty knowledgeable.
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Assuming that they used 3000 hp to go 480 they would need a additional approx 400 hp to make 500. Just a 1/4 turn of the boost control!
It is interesting how much down force they must be generating as they certainly appear to be able to go 500 with two wheel drive, and at one time it was "written in stone" that to go really fast you must have 4 wheel drive.
Rex
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What was the reasoning that you required 4 wheel drive to attain high speed ?
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I have always thought that a neglected area in LSRing was tire rubber compound. I've only recently given it more thought because of a conversation with Marlo. He told me that his car basically ripped up the Mickeys, much as you see the Speed Demon do on every run. He somehow got ahold of some 30" Goodyears with enough of a different compound to keep from spinning the tires and not throwing or spinning the rubber off. He had the tits still on them after the last time it ran in Au.
The reason I believe this is as a former drag racer I am aware of the huge amount of compounds available to drag racers through several manufactures. As a NASCAR fan I know they are always messing around with different compounds for different tracks. It is the same for nearly ever form of racing. If you have been around for any time at all, you know that in LSR we are lucky to have any tires at all. If someone did have enough money they could get a run of a softer tire from M/T and maybe even an extra 20 thou or so rubber just to give it a go. I know, wish full thinking :|
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I have always thought that a neglected area in LSRing was tire rubber compound. I've only recently given it more thought because of a conversation with Marlo. He told me that his car basically ripped up the Mickeys, much as you see the Speed Demon do on every run. He somehow got ahold of some 30" Goodyears with enough of a different compound to keep from spinning the tires and not throwing or spinning the rubber off. He had the tits still on them after the last time it ran in Au.
The reason I believe this is as a former drag racer I am aware of the huge amount of compounds available to drag racers through several manufactures. As a NASCAR fan I know they are always messing around with different compounds for different tracks. It is the same for nearly ever form of racing. If you have been around for any time at all, you know that in LSR we are lucky to have any tires at all. If someone did have enough money they could get a run of a softer tire from M/T and maybe even an extra 20 thou or so rubber just to give it a go. I know, wish full th inking :|
No clue if its been tested or not but what about nitrogen in the tires? It must be a temperature issue.
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We have been running nitrogen in our tires for years. Less fluctuation due to temperature
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The reason that nitrogen can have an effect on tire pressure is that the way nitrogen is refined out of the air. It has an extremely low due point i.e. very low water content. Heat in tires is generated by tire flex and slip, if you have any water in the tire it will expand at a faster rate than a normal gas because it is turning to steam. A dry gas expands proportional to its change in temperature (in degrees kelvin ). When water changes to steam at 212F it expands at a ratio of 1700:1. You can get the same affect by using air that has been compressed and then dried using a desiccant dryer which typically reduces the due point to -40 degrees F, a refrigerant air dryer reduces the due point to 32 degree F at best. So you can certainly use compressed air for your tires but the compressor needs to have a desiccant dryer, or just use nitrogen.
Rex
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I've heard of local tire dealers pushing nitrogen for an extra cost saying it is safer. Street cars have run on air for over a century. I understand race cars are different.
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Costco uses nitrogen and green valve stem caps to indicate it.
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We have also used Nitrogen in our tires for years... easier to take a small "walk around" bottle than than a compressor.
John C, the problem with tires for some folks is a heavy right foot... luckily for us we use small enough motors that spinning the tires is about impossible. :? :roll:
Something to consider, traction on salt is about 60% of cement :cheers:
Tire slip is one of the enemies...
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The reason that nitrogen can have an effect on tire pressure is that the way nitrogen is refined out of the air. It has an extremely low due point i.e. very low water content. Heat in tires is generated by tire flex and slip, if you have any water in the tire it will expand at a faster rate than a normal gas because it is turning to steam. A dry gas expands proportional to its change in temperature (in degrees kelvin ). When water changes to steam at 212F it expands at a ratio of 1700:1. You can get the same affect by using air that has been compressed and then dried using a desiccant dryer which typically reduces the due point to -40 degrees F, a refrigerant air dryer reduces the due point to 32 degree F at best. So you can certainly use compressed air for your tires but the compressor needs to have a desiccant dryer, or just use nitrogen.
Rex
While much of what Rex stated is valid, things kind of went off the rails when talking about boiling water in the tires. While some vehicles (like tractors) have liquid water in the tires, it is not likely any LSR competitors do, nor do they likely get up to boiling temperatures.
Perhaps to clarify the issue of using Nitrogen in the tires it would be useful to consider the following. From thermodynamics and the related gas laws, it is possible to derive the following relationship for a mixture of gasses, namely air and water vapor.
V = (1 + xRw/Ra) Ra T/p
Where
V = volume
T = temperature
p = pressure
Ra = gas constant for air
Rw = gas constant for water vapor
and Rw/Ra = 1.61
x = specific humidity = mw/ma = ratio of the mass of water vapor to the mass of air
So looking at the formula, if there is dry air alone, that is, x = 0, the relationship simplifies to the more commonly familiar V = RT/p. Which says that for volume to remain constant (assuming the interior volume of an inflated tire is essentially constant), if the temperature were to rise, the pressure would also have to rise in proportion, to keep V = constant. Pressure goes up in a hotter tire.
If we then consider water vapor to be in the mixture, x will be greater than zero and since Rw/Ra = 1.61, the value in the parentheses will be greater than 1 and consequently, given a temperature increase, p will have to increase at a greater rate than before in order to comply with a constant volume requirement. Ergo, air with water vapor will produce a larger pressure increase.
So, if the nitrogen gas is ?dry? it would not produce as much pressure rise as possibly water vapor contaminated gas would, and since the gas constant for nitrogen Rn is slightly less than that of air, another minor effect would be acting to minimize the pressure rise.
However, all of these effects are relatively small and of dubious value for LSR competition.
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I think it's "dew" (like dew on the leafs) rather than "due" (like your library book).
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Who the heck fills tractor tires with water??....Beet juice is the way to go.
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I think it's "dew" (like dew on the leafs) rather than "due" (like your library book).
I would like to demote our forum spell checker until he corrects his own name to Stand.
Thanks.
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Wait until Jim corrects your grammar...and your grandpa too. :cheers:
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I think it's "dew" (like dew on the leafs) rather than "due" (like your library book).
I would like to demote our forum spell checker until he corrects his own name to Stand.
Thanks.
The only position lower than "spell checker" is "coma cop" and that position is already filled. :wink:
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If I slip into a coma I hope someone calls a doctor rather than a cop..... :cheers:
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"I would like to demote our forum spell checker until he corrects his own name to Stand."
Stan is a shortened version of Stanley -- like Ray is short for Raymond. I guess I could change it to Stanl, but dad always said, "Stan, back!"
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Long winter? :roll:
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"I would like to demote our forum spell checker until he corrects his own name to Stand."
Stan is a shortened version of Stanley -- like Ray is short for Raymond. I guess I could change it to Stanl, but dad always said, "Stan, back!"
If that is the case..I should change my screen name to "Dang it Jer"
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Hey! I have made a ton of post's on this site and between Stan, SS and SSS I have been chastised, bullied, thrown under the bus, held to the fire, fed to the wolves, ground by the grinder (think FARGO) for a few slip ups (take it for what it's worth) as if I give a flying rats ass.
If you stay with it long enough, they will give up after ten or fifteen years as they realize that the goal is to keep them on their feet, grinding their collective teeth, seething in their own anger and stewing in their own pot!
Most (or mostly) Sincere,
"One Run" Bob, out......................................... :dhorse:
p.s. What ever became of Mr. Green ? :mrgreen:
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Good one Bob...... :-)
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Hey! I have made a ton of post's on this site and between Stan, SS and SSS I have been chastised, bullied, thrown under the bus, held to the fire, fed to the wolves, ground by the grinder (think FARGO) for a few slip ups (take it for what it's worth) as if I give a flying rats ass.
If you stay with it long enough, they will give up after ten or fifteen years as they realize that the goal is to keep them on their feet, grinding their collective teeth, seething in their own anger and stewing in their own pot!
Most (or mostly) Sincere,
"One Run" Bob, out......................................... :dhorse:
p.s. What ever became of Mr. Green ? :mrgreen:
https://www.youtube.com/watch?v=F7HfMwWIJtE
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Wow One run.... you're not going snowflake on us are you.... :evil: get your shit together and let's go racing.
BTW, running a little short on cash... can you lend me a $100 till my hunch back brother straightens up 8-)