Author Topic: Brand new at this please help !  (Read 83973 times)

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Offline taper41

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Re: Brand new at this please help !
« Reply #30 on: May 25, 2012, 06:05:01 PM »
I apologize fellas, i put my location in my profile.


Offline taper41

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Re: Brand new at this please help !
« Reply #31 on: May 25, 2012, 06:09:22 PM »
Okay, Mr. Taper -- glen has asked a fair question and I'll second it.  Would you please be so kind as to put your location into your "profile" page back in registration -- so we'll at least know where you're located.  Not street address -- but city and state is good so we know if there's a racer nearby that can visit and help out -- or if you can visit and help one of us.

Also -- how 'bout some background?  Where, for example, did you get the knowledge needed to ask the basic questions you're asking?  Have you raced in other forms of wheeled/engine driven vehicles.  I could go on -- but we'd all rather have you take a moment and tell us.  I see you're on line right now -- so take a little time and give us the background, please.  I'll point out that if you don't give us location -- I'll assign one to you and it might not be correct :evil:!

im asking these questions, for two reasons it is something im interested in , and for the main reason as its a project for physics, which is why there are certain aspects of the top speed and 2 or 4 wheel cars i am being theoretical about . any input on my last post, that although 2 wheel machines are more aerodynamic, theoretically 4 wheels should be able to handle more power to basically negate the advantage of being more aerodynamic

Offline Glen

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Re: Brand new at this please help !
« Reply #32 on: May 25, 2012, 06:16:17 PM »
Taper, thanks and there are several in NY that are land speed racers 2 and  4 wheels
Glen
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South West, Utah

Offline V8Pinto

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Re: Brand new at this please help !
« Reply #33 on: May 26, 2012, 10:42:04 AM »
im asking these questions, for two reasons it is something im interested in , and for the main reason as its a project for physics, which is why there are certain aspects of the top speed and 2 or 4 wheel cars i am being theoretical about . any input on my last post, that although 2 wheel machines are more aerodynamic, theoretically 4 wheels should be able to handle more power to basically negate the advantage of being more aerodynamic

I love it when people say "theoretically".  "Theoretically", anything is possible.  Anyway...  Your postulation, argument, whatever it is doesn't take into account the area of said tires.  "Theoretically" the surface area or volume of 2 tires could equal 4 tires.  What I mean is, you could make a tire that was as wide as a car (think Lincoln Log) and have two of them and those two tires would support more weight than 4 conventional shaped tires.  BTW - "tires" is a general classification not related to the material that the "tire" is made from. 

Would I want to drive this?  No.  Would it have a large aero penalty?  yes.

Theoretically, I do not believe the statement that 4 tires can resist more force than 2 is true as this is really dependent on surface area and contact patch as is the traction coefficient.  Bulldozers only have two drive surfaces and I would classify that as an Uber drive surface.  Wait - bulldozers have like 30 wheels..  Now I'm off in the crusties.
Shane
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Offline fastman614

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Re: Brand new at this please help !
« Reply #34 on: May 26, 2012, 12:53:54 PM »
Taper41, I have a feeling you are going to make a "fine" mechanical engineer! You'd probably be welcomed with open arms into the company for which I work.... (work is what I do to earn the money to do what I really WANT to do...play with hotrods ...)

V8Pinto.... you ARE correct on your tire analogy - I was thinking Flintstones myself.... BTW, did anyone ever wonder how the steering in that car actually worked?
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Offline taper41

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Re: Brand new at this please help !
« Reply #35 on: May 26, 2012, 05:43:06 PM »
im asking these questions, for two reasons it is something im interested in , and for the main reason as its a project for physics, which is why there are certain aspects of the top speed and 2 or 4 wheel cars i am being theoretical about . any input on my last post, that although 2 wheel machines are more aerodynamic, theoretically 4 wheels should be able to handle more power to basically negate the advantage of being more aerodynamic

I love it when people say "theoretically".  "Theoretically", anything is possible.  Anyway...  Your postulation, argument, whatever it is doesn't take into account the area of said tires.  "Theoretically" the surface area or volume of 2 tires could equal 4 tires.  What I mean is, you could make a tire that was as wide as a car (think Lincoln Log) and have two of them and those two tires would support more weight than 4 conventional shaped tires.  BTW - "tires" is a general classification not related to the material that the "tire" is made from.  



Would I want to drive this?  No.  Would it have a large aero penalty?  yes.

Theoretically, I do not believe the statement that 4 tires can resist more force than 2 is true as this is really dependent on surface area and contact patch as is the traction coefficient.  Bulldozers only have two drive surfaces and I would classify that as an Uber drive surface.  Wait - bulldozers have like 30 wheels..  Now I'm off in the crusties.



i understand what you are saying here, my argument is based on the benefit of surface area and contact patch if the wheels were the exact same on a 2 wheeled vehicle and the 4 wheeled vehicle, the 4 wheeled vehicles weight will always be distributed better and therefore more stable than 2, allowing it to stand up to more resistance , am i not right about that ?

although i know drag racing is based on a totally different mindset , still some of the same principals are applied on what the cars or bikes can or cannot handle.  the fastest thing on two wheels are the top fuel nitro bikes , 1500 bhp and weigh around 1000 lbs, while the top fuel cars have over 7000 bhp and 2500 lbs, the motorcycle would never be able to be stable with the same amount of force, and if they were able to ever get a motorcycle to run with 7000 bhp then by then how much further would that have pushed the envelope with 4 wheels ? how important is aerodynamics vs the importance of horsepower when it comes to top speed,one makes it easier to to faster by limiting resistance, while the other makes its possible to go faster by adding more force to combat the resistance although 2 wheels will always be more streamlined , 4 will always be able to control and be stable with a higher amount of power, if the wheels on both vehicles were identical , would this not eventually cancel each other out , and there for this debate could go on and on where each can gain the upper hand while the other perfects its advantages to surpass ,yes ?
« Last Edit: May 26, 2012, 05:50:05 PM by taper41 »

Offline fastman614

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Re: Brand new at this please help !
« Reply #36 on: May 27, 2012, 04:57:27 AM »
Taper41 - I think you are beginning to see the "real world" take on this topic....

You have the "in a perfect situation" (or the in theory) part .... and then you trade certain things off for practicality, usability, efficacy etc.... then you get the final design...

and the "pie in the sky" visionaries keep working on redesigning the world to fit the theory.... Several of the engineers with the company for who I work seem to be rather fixated on the "designing of the perfect world concept" - although, to ALL of their credit, they are often(usually, really) practical, pragmatic and conversant in/understanding of cost/benefit analysis....
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Offline fastman614

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Re: Brand new at this please help !
« Reply #37 on: May 27, 2012, 05:14:02 AM »
So, to everyone who posted so far, I think we just need to get this young fella to Bonneville and have him hang out with a number of us .... study the cars .... ask questions.... get involved in some work aspects and he could be another "Lynn Yakel" or Jocko Johnson....

And, if he flew out on my Air Miles credits, he would HAVE to design a streamliner body for us!!!!!
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Offline taper41

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Re: Brand new at this please help !
« Reply #38 on: May 27, 2012, 06:39:31 AM »
thank you fast man , i would love to be make the trip, i would learn so much

do you have any feelings toward my statement about the drag vehicles?
or the aerodynamics vs horsepower  on how they each have their way of overcoming resistance and friction (2 wheels aerodynamic efficiency 4 wheels ability to handle more force/power) or is it kind of like using a saw to cut cement blocks or a jackhammer to break the same cement apart, ending in the same result ?
would you say they have equal value when it comes to top speed , or is one more important than the other when you take these key elements
« Last Edit: May 27, 2012, 06:41:09 AM by taper41 »

Offline hotrod

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Re: Brand new at this please help !
« Reply #39 on: May 27, 2012, 11:51:20 AM »
Quote
do you have any feelings toward my statement about the drag vehicles?
or the aerodynamics vs horsepower  on how they each have their way of overcoming resistance and friction (2 wheels aerodynamic efficiency 4 wheels ability to handle more force/power) or is it kind of like using a saw to cut cement blocks or a jackhammer to break the same cement apart, ending in the same result ?
would you say they have equal value when it comes to top speed , or is one more important than the other when you take these key elements

In an abstract sense power and reduced aero drag  are equivalent, you can trade one for the other and get the same result. In the real world of car building you make choices. For example you choose a class to run for a record in. By choosing the class you have also chosen some rules that place limits on how much power you can make. The class determines how big of an engine you can run. The maximum engine displacement you have chosen by picking that class puts a pretty solid wall upon the maximum power you are likely going to be able to make. But on top of that you probably have a preference for a certain engine type/manufacture. Perhaps it is because you have several of a certain type of engine in storage and you want to use them, or you are highly familiar with a certain manufactures engine.

In any case, you now have a displacement limit and based on economic availability or familiarity you are limited to a certain family of engines. At that point you can make an educated guess of the maximum power you are likely to get out of that engine package. Once you know this power limit, and you know the top speed you need to achieve to set a record, that in effect puts an upper limit on how much aero drag you can have and still run the record speed. If you are in a stock body production class that gives you very limited options on what you can do to reduce drag and still meet the rules, you need to decide if the body styles available that you can run your choice of engines in can give you low enough drag to run record speeds at the power you are likely to make in that engine size class.

If the answer is yes, proceed to build the car, if maybe decide if you are stubborn enough to try to push the limits hard enough to get your record in spite of the limitations you have to deal with, if the answer is no, then go back to step one, and reconsider your class choice, engine choice, body style choice and record to break choice or all your assumptions about how much power you can make with the engine or what the rules will let you do to reduce drag.

It is a never ending process of evaluating that series of decisions, and finding places or ways you can push back the limits by making more power than others do, or finding a way to reduce drag (maybe reduce rolling resistance rather than aero drag) perhaps you find a way to reduce internal friction in the motor or drive train so more of the power it makes gets to the wheels.

keep asking questions that is how you figure out where those limits are!

Larry

Offline fastman614

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Re: Brand new at this please help !
« Reply #40 on: May 27, 2012, 02:48:45 PM »
thank you fast man , i would love to be make the trip, i would learn so much

do you have any feelings toward my statement about the drag vehicles?
or the aerodynamics vs horsepower  on how they each have their way of overcoming resistance and friction (2 wheels aerodynamic efficiency 4 wheels ability to handle more force/power) or is it kind of like using a saw to cut cement blocks or a jackhammer to break the same cement apart, ending in the same result ?
would you say they have equal value when it comes to top speed , or is one more important than the other when you take these key elements


Taper41,
Hotrod made a few important points in his post.... areodynamics in drag racing - especially when stock bodied cars began going faster than, say, 150 mph (I am thinking PRO Stock here) in the 1970s, the auto manufacturers were building cars for improved fuel economy and two ways of achieving that was by building the cars both smaller and "slipperier"... The PRO Stock people (and most other drag racers) were constantly using ever newer body designs for the cars they were running - and the speeds increased along with their doing so (although, in the specific case of PRO Stock, there were, I believe, rule changes with regard to minimum weight and increased engine sizes) ... other factors did come into play as well - things such as improved traction tires, "launch" theory, transmissions, larger airflow cylinder heads etc.

Okay, now, in the case of dragsters one has to look back at the perennially competitive cars in the 1960s and 1970s.... the classic "rail job" look of the "slingshot" dragsters of the early years of drag racing was constantly being updated - most noticeably by building full bodies over the frame rails ahead of the engine and applying aerodynamic tricks to bodywork around the cockpit.

With the advent of the rear-engined dragster in the early 1970s, new aerodynamics came into being ... one thing that helped the rear -engined cars (nearly immediately) achieve quicker ets and terminal speeds was with the air being more effectively displaced by the cowling around the driver who was then ahead of the engine, an aerodynamic advantage that was soon capitalized upon by pretty well ALL top fuel and faster dragster builders came to be.....

This spawned a brief era where fully streamlined dragsters were seriously experimented with.... several met with ignominious ends and none that I recall worked out as the builders had hoped.... Don Garlits (and his cadre of assistants), of course was one of the biggest innovators of the era... going so far as to contract a renowned (amongst land speed racers, anyway) streamliner body builder named Jocko Johnson to design and build at least one (if not more) full bodies for his experimentation.

To this day, dragsters ARE using many aerodynamic tricks in order to continue to go quicker/faster - i.e. wings (front and rear) - the purpose of which is to increase downforce as the cars' speeds increase during their runs - and is, by definition, NOT increasing the aerodynamic advantage of the car but using that laminar airflow to achieve a "competing", if you will, objective, namely, increased traction.... air deflectors ahead of the WIDE rear tires etc... (both itemized items being part of the "trade-off" that occurs in order to achieve the end objective)

.... about your analogy regarding using a saw to cut up bricks or a jackhammer to break them.... both methods will get you smaller pieces of bricks... if, however, the object is to have smaller, re-usable pieces of bricks to be cemented in to corners or for a special "bricking" application, rather than a heap of rubble to be used as "landfill" in a boggy area on your property, the two methods of making smaller pieces of bricks are not going be interchangeable.
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Offline fastman614

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Re: Brand new at this please help !
« Reply #41 on: May 27, 2012, 02:57:45 PM »
Taper41,
Pasted in below is a post from another thread on this site - it is NOT exactly specific to your initial question but there is a link at the bottom of it to - ....markviii dot org

The article is, in and of itself interesting as it talks about a land speed record attempt that came from "out the back door" at Ford Motor Company... and the aerodynamics of the car body were pretty much the biggest advantage they had - they did not have big horsepower....
   
Re: Hot Rod Lincoln :2012 Bonneville ..................
« Reply #14 on: Today at 11:23:54 AM »
Quote
Quote from: fastman614 on Today at 03:31:01 AM
.

I figure that the aero on a car like this is every bit as good as a Camaro or Firebird of the same vintage.... although I think that the 'stang - at about .41 or .42 is a smaller car and may actually cause a few less horsepower being lost due to the frontal area vis-a-vis the Cd effectively cancelling out the larger frontal area of the Lincoln with the lower Cd number.... with an F class engine, though, it may be more academic than real. 

The Lincoln IS a nice looking car!

explain ?  please.

88-90 Mustangs have a cd of .38  the MKViii at .31 should take less hp to run over 150 mph. Depending on what intake system we use( Carbs, MFI, EFI) the 2.9ltr should be in the range of 375-400hp at 9,000, the turbo engine 750hp at 8,000- 8,500 and that's not running it on "kill".

The N/A engine will will have a 5 speed gear box with 5th being 1:1, the BGC engine will run a 5 speed trans with a slight over-drive ( current line of thinking anyway)

In any instance this year should be an interesting learning experience with the car. 

we have lots to get done in the next 70 or so days.......................

A little history I found interesting:

http://www.markviii.org/LOD2/bonneville.htm

Jon
No s*** sticks to the man wearing a teflon suit.

Offline taper41

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Re: Brand new at this please help !
« Reply #42 on: May 27, 2012, 04:33:23 PM »
the article along with your statements seem to line up with the fact that aerodynamics and horsepower both have an equal part in the formula of top speed, and that if you lack one you have to make it up with the other , one doesnt seem to be more important to the other the 2 wheel design might always have the aero advantage but the 4 wheels design should always have the horsepower advantage.   but yes the article did help. plus ive always loved f bodies. 02 red z28 was my first love

Offline tortoise

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Re: Brand new at this please help !
« Reply #43 on: May 27, 2012, 05:46:24 PM »
As speeds get faster and faster, and courses stay the same length, and coefficient of friction between the tires and the salt remains the same, traction-constrained acceleration, rather than top speed, becomes a limiting factor, one that cannot be overcome by adding just adding more power or ballast. You need aerodynamic downforce. Current fast streaminers seem to be at or around this threshold.

Presumably there is some limit to the amount of downforce the salt surface will take before breaking up or collapsing under the pressure. If this limit is reached, only lower drag will enable higher speed. (More wheels, or fatter tires might help, I guess, though this would have various bad effects.)

Thus, drag is more important than power, at some ultimate level. Reducing weight also becomes a priority.
« Last Edit: May 27, 2012, 06:21:33 PM by tortoise »

Offline taper41

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Re: Brand new at this please help !
« Reply #44 on: May 27, 2012, 09:34:36 PM »
i understand but you also made a point for more wheels which im assuming would disperse the drag from the downforce that , we talked about the benefit of 4 wheels vs 2 when it came to rolling resistance to having a lighter load on each individual tire spreading the pressure from the downforce over a larger base rather than all the pressure taken by two, which would play into the salt giving way , and if acceleration comes into play ,typically 4 wheels do this better than 2, contact patch , traction like you have stated.

but i believe your also talking about using aerodynamics in a different way, using downforce to benefit rather than building something to avoid it

i would love to see top speed runs done somewhere else besides the salt flats on a harder surface