Wheels & Times ?
- Thread starter Momentum Racing
- Start date
COG and COM are the same only if the gravitational field does not vary over the extent of the body. While this may have no practical role in a Pinewood car, your statement is incorrect nonetheless.
You may find the Center Of Gravity section particularly pertinent.
https://en.wikipedia.org/wiki/Center_of_mass
Some others agree.
http://physics.stackexchange.com/questions/50107/what-is-the-difference-between-center-of-mass-and-center-of-gravity
You may find the Center Of Gravity section particularly pertinent.
https://en.wikipedia.org/wiki/Center_of_mass
Some others agree.
http://physics.stackexchange.com/questions/50107/what-is-the-difference-between-center-of-mass-and-center-of-gravity
- Nov 24, 2011
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Brain overload!
Many years ago when I was taking classes for my Mechanical Design degree I took a project based design class. When we started working on our projects the instructor wrote K.I.S. on the board.
Keep It Simple!
Many years ago when I was taking classes for my Mechanical Design degree I took a project based design class. When we started working on our projects the instructor wrote K.I.S. on the board.
Keep It Simple!
I do believe he missed an "S", at least this is the way I've always heard it repeated. Or was he being sensitive...Mister B Racing said:
Honestly guys I view things much more simple than it might appear. For me it's really as simple as starting with the biggest motor I can, and maintaining as much of that motor as possible.
Practically speaking the biggest motor is the most amount of weight placed the highest on the hill. If the sum of the energy losses is the same, a 24 cube "big block" motor(12x12) placement will beat a 24 cube (12x10x2) placement "small block" motor every time. The "biggest motor" isn't extremely difficult to attain, I find minimizing the losses a more difficult task.
Let's take BASX cars as an example. They are all very simple and similar aerodynamically, not much of a difference there in lost energy. I'd bet most top cars are running 24 cube " big blocks " as well, not much of a difference there, although I'm sure some seasoned vets have found a synergy in running a smaller motor and lower overall energy losses and are also competitive, if not faster.
Tuning....the rear axles are set, if you're as adamant as I am about running a 12x12 cube motor, what is really left to tune other than wheel gaps and steer ? Anyone can set wheel gaps, setting steer is a simple matter of a few test passes on a track. I believe in the least amount of steer as possible. If you're running 4"-4' you better be making up for it somewhere else.
Wheels and axles....this is where I believe the perennial winners set themselves apart from everyone else, and is the key to this sport.The losses here separate 1st through last place at NPWDRL levels.
Right or wrong as it may be, for now I plan on running 24 cube big blocks and focusing strongly on wheel and axle prep.
This sport really is pretty simple, yet can be so complicated.
Practically speaking the biggest motor is the most amount of weight placed the highest on the hill. If the sum of the energy losses is the same, a 24 cube "big block" motor(12x12) placement will beat a 24 cube (12x10x2) placement "small block" motor every time. The "biggest motor" isn't extremely difficult to attain, I find minimizing the losses a more difficult task.
Let's take BASX cars as an example. They are all very simple and similar aerodynamically, not much of a difference there in lost energy. I'd bet most top cars are running 24 cube " big blocks " as well, not much of a difference there, although I'm sure some seasoned vets have found a synergy in running a smaller motor and lower overall energy losses and are also competitive, if not faster.
Tuning....the rear axles are set, if you're as adamant as I am about running a 12x12 cube motor, what is really left to tune other than wheel gaps and steer ? Anyone can set wheel gaps, setting steer is a simple matter of a few test passes on a track. I believe in the least amount of steer as possible. If you're running 4"-4' you better be making up for it somewhere else.
Wheels and axles....this is where I believe the perennial winners set themselves apart from everyone else, and is the key to this sport.The losses here separate 1st through last place at NPWDRL levels.
Right or wrong as it may be, for now I plan on running 24 cube big blocks and focusing strongly on wheel and axle prep.
This sport really is pretty simple, yet can be so complicated.
Yes keeping it simple is good. I am by no means the fastest racer around, but what I have learned is that each car you build is different exspecially when it comes to the amount of steer they need and how they are weighted and how the wheels are gapped. I have cars that need just 2-1/2" of steer and others that need 6" or 7" or more of steer and each one is weighted a bit different than the other and the wheel gaps are different. It's what they need to keep from wiggling on the track and they run the fastest times no matter how I think they should be setup.
I would love to be able to say I'm going to build a car, put 24 cubes in it, set the steer at 2" over 4', just pick a wheel gap and just concentrate on wheel and axle prep and start winning races! It does not happen that way! Not even close! Most times the racer in the next lane knows everything you do and more and they are going to beat you. It's just the way it is. You should listen to Zeebzobs latest podcast. JBD gives some very good info to think about. You may not ever win a race at this level, take and keep lots of notes on each of your cars to see what works and does not work, each month race your self and compare your times to the last race to see how you are progressing, what is working for him on his cars may not work for you. There were several other races that gave very good tips also.
In 2-1/2 years I have been fortunate enough to win one race over at the APR league in their Cubby Pure Stock class. I have not been able to win again!
There are a lot of really good racers in all of the different leagues that can offer advice and point you in the right direction to building cars, but the only way to find out how good your building and tuning skills are is to start racing your cars with the rest of us!
Steve - Mister B
I would love to be able to say I'm going to build a car, put 24 cubes in it, set the steer at 2" over 4', just pick a wheel gap and just concentrate on wheel and axle prep and start winning races! It does not happen that way! Not even close! Most times the racer in the next lane knows everything you do and more and they are going to beat you. It's just the way it is. You should listen to Zeebzobs latest podcast. JBD gives some very good info to think about. You may not ever win a race at this level, take and keep lots of notes on each of your cars to see what works and does not work, each month race your self and compare your times to the last race to see how you are progressing, what is working for him on his cars may not work for you. There were several other races that gave very good tips also.
In 2-1/2 years I have been fortunate enough to win one race over at the APR league in their Cubby Pure Stock class. I have not been able to win again!
There are a lot of really good racers in all of the different leagues that can offer advice and point you in the right direction to building cars, but the only way to find out how good your building and tuning skills are is to start racing your cars with the rest of us!
Steve - Mister B
Good points Mister B......for me it's a question of why wouldn't someone want to start with the most potential ? Without the knowledge many long time racers have one must start somewhere, IMHO initially limiting your potential puts you at a disadvantage from the start.
At the level the top builders play I just have a hard time believing a 6" steer car can compete with a 2" steer car. My feeling is a 6" car has other build issues as it shouldn't take that amount of steer to keep it straight.The 6" car is using more of its energy to get down the track, it has to be made up somewhere or it will lose the race.I could be well of base here, but if I had a car that needed 6"-7" of steer I would likely throw it in the trash and start over.
I absolutely believe there are synergistic combinations that allow smaller "motors" to win, but the top builders are pretty tight lipped about their set-ups in that regard.As hyper competitive as the sport is I doubt most will tell you how much steer they are truly running as well. I don't blame them, knowledge is power in this game. It will take a lot of trial and error to find a competitive combination here.
At the level the top builders play I just have a hard time believing a 6" steer car can compete with a 2" steer car. My feeling is a 6" car has other build issues as it shouldn't take that amount of steer to keep it straight.The 6" car is using more of its energy to get down the track, it has to be made up somewhere or it will lose the race.I could be well of base here, but if I had a car that needed 6"-7" of steer I would likely throw it in the trash and start over.
I absolutely believe there are synergistic combinations that allow smaller "motors" to win, but the top builders are pretty tight lipped about their set-ups in that regard.As hyper competitive as the sport is I doubt most will tell you how much steer they are truly running as well. I don't blame them, knowledge is power in this game. It will take a lot of trial and error to find a competitive combination here.
Momentum Racing said:
I made the finals for the 1st time ever by the skin of my teeth, and in the Nationals. It took me three years. Some have did it in a shorter period of time, some took longer, and some will never do it. Am I a top racer? No.
But I will tell you this. I will certainly tell anyone how much steer my top car was running. It was 5 1/2 inches over 4'. Could it be faster will less? Don't know - I would have to change my weighting. Do I know what my COM was? Not a clue. I could post all of the stats on my car but I know a new racer would not be able to take advantage of that information. In fact, I usually get criticism such that I should be doing things differently. Maybe so, but that something we each have to determine. Benji, Brian, Joel, Pony, Kinser, Troy, whoever, could tell me everything they did, but I still do not have the skills just yet to compete with them. I have to find them and develop them.
Gravity had made a suggestion to the top racers that if they sell a car, sell it disassembled. I really hope this happens and the racer that buys the car, posts about it. They are going to find even with the wheel and axle prep, it is not going to be much more than mid-pack car, because they do not have the skills to maintain it just yet. What they will get is something to look at and inspect, to compare to their own builds, which in some cases, is worth the money. That does not mean buying a car will help the slowest racer as much as it can help someone more experienced. Its up to each builder to figure that out.
I am not trying to discourage any new racer saying that you are forever doomed to be last because a top racer is quiet about there builds, but hoping they understand that knowing the stats of a particular car is not going to help as much as you think. I'm learning that myself more and more with every build. PM me if there is something specific you want to know about my car. Look it up - Green Envy at Nationals. It did OK. For myself, I need to turn OK into better somehow knowing how I got to OK. A top racer telling me what he did is not going to help muck, if at all, because they got to OK differently.
Does this make sense?
Bregal....I know where you're coming from and much of what you said makes perfect sense, but let me ask you, what was your weight placement for Green Envy?
It's funny you mention the sale of winning cars, I was just thinking a top builder would be a fool to sell his winning car without first "adjusting" it. I'm not ashamed to say If I can make it to a large event I would be willing to buy the winning car, if, and only if I can grab it right off the track before anyone touches it. However, I highly doubt the builder would allow that. Dissection of the car could save years of trial and error headaches.
There is certainly a degree of skill involved in building a winning car. I believe however, that the biggest component is acquired knowledge. Not gloating in any way, but I generally pick up things quickly and am usually pretty good at anything I apply myself to. If the top builders showed me exactly what they do I feel I could mimic their results pretty quickly. I don't think you give yourself enough credit. If you were sitting on a bench next to any of the names you mentioned building cars together, in what area do you feel you could not match their actions?
It's funny you mention the sale of winning cars, I was just thinking a top builder would be a fool to sell his winning car without first "adjusting" it. I'm not ashamed to say If I can make it to a large event I would be willing to buy the winning car, if, and only if I can grab it right off the track before anyone touches it. However, I highly doubt the builder would allow that. Dissection of the car could save years of trial and error headaches.
There is certainly a degree of skill involved in building a winning car. I believe however, that the biggest component is acquired knowledge. Not gloating in any way, but I generally pick up things quickly and am usually pretty good at anything I apply myself to. If the top builders showed me exactly what they do I feel I could mimic their results pretty quickly. I don't think you give yourself enough credit. If you were sitting on a bench next to any of the names you mentioned building cars together, in what area do you feel you could not match their actions?
V
Vitamin K
Guest
Even if I won the lottery tomorrow, I would have no desire to buy a winning car, even a fresh-off-the-tracks one. There's just no appeal to me in something like that. Experimentation and discovery are easily more than half the fun of the hobby.
Vitamin K said:
Vk....I understand that point of view as well, but where is the line drawn ?
I love to tinker and experiment as you do, but I am also open to advice and tips, especially from those who have proven results.
Is dissecting a winning car really any different than someone like Kinser telling you how he preps wheels, or JDB telling you what type of lube he uses, or QT telling you where he places his weights?
Is a winning builder voicing what it takes to win, different than him showing what it took to win in the form of the actual car?
V
Vitamin K
Guest
Momentum Racing said:
Looking at somebody else's work can only show you the "what." I'm far more interested in the "why." Maybe a racer distributes his weight in a certain pattern and share the info. Yes, I'm interested in knowing that, but my real interest is why its effective. Same goes for lube and prep. Everybody does things differently, and what works for one person might not work for another. My true curiosity lies in figuring out the mechanism that produces the results, not any particular implementation thereof.
Momentum
"At the level the top builders play I just have a hard time believing a 6" steer car can compete with a 2" steer car. My feeling is a 6" car has other build issues as it shouldn't take that amount of steer to keep it straight.The 6" car is using more of its energy to get down the track, it has to be made up somewhere or it will lose the race.I could be well of base here, but if I had a car that needed 6"-7" of steer I would likely throw it in the trash and start over."
This is a very interesting comment too me and I'm not really sure how to reply to this but I will try. My very first car I had was a car that I had gotten on eBay with some vintage PWD cars I had bought. It sat in a box in my basement for like a year. It is called 2nd Hand Smoke. I sanded and re-painted the body, added rear fenders and put good wheels and axles on it. I was invited to test it at Zeebzobs Race Shop. The guys there helped me track tune it because I had no clue on what to do. The weight in the car is not a 12 x 12 setup like you mentioned in your post and the car has 6" of steer over 4'. I sent the car into NPWDRL Man of the Mountain race in December 2013. It was my very first race and after 4 runs that car with 6" of steer that you would probably trash and start over set 2 track records. I will find the video link for you if you would like to see it. I raced that car in the novice class in 2014 and ended up third overall at the end of the season.
All I'm trying to say here is that yes you need some sort of baseline to start with weighting wise and steer wise and wheel gap wise, and make changes from that baseline, but just because a car has more than 2" of steer over 4' does not mean it has build issues. Drill jobs are different, each block of wood is different, how the car is shaped is different, the angle of the front dominate wheel is different from car to car, there are just to many variables in each build to just bluntly say a 6" steer car can't compete with a 2" steer car or that a 6" steer car has build issues. Don't give up on a car that takes more steer than you think it should, you will find that out as you build cars and gain more experience.
Also like you mentioned above, I bought a fully assembled car built by a top racer. I thought I could examine it, take notes and duplicate what this top builder had done. I have news for you, it does not happen, if it did everyone would be fast and contending for National Championships. I ended up with a car that was fast and a top contending car and made it dog slow. As hard as I tried even though I took notes on how the car was set up, I could not prep it like it was or get it back together and duplicate what that racer had done even though I had all of the information to do so. A top racer could give everything he does on his winning car, and just because it works for him does not mean it will work for you. You will discover this as you build a car and try to duplicate what others are doing.
I look forward to racing against you in up coming races.
Steve - Mister B
"At the level the top builders play I just have a hard time believing a 6" steer car can compete with a 2" steer car. My feeling is a 6" car has other build issues as it shouldn't take that amount of steer to keep it straight.The 6" car is using more of its energy to get down the track, it has to be made up somewhere or it will lose the race.I could be well of base here, but if I had a car that needed 6"-7" of steer I would likely throw it in the trash and start over."
This is a very interesting comment too me and I'm not really sure how to reply to this but I will try. My very first car I had was a car that I had gotten on eBay with some vintage PWD cars I had bought. It sat in a box in my basement for like a year. It is called 2nd Hand Smoke. I sanded and re-painted the body, added rear fenders and put good wheels and axles on it. I was invited to test it at Zeebzobs Race Shop. The guys there helped me track tune it because I had no clue on what to do. The weight in the car is not a 12 x 12 setup like you mentioned in your post and the car has 6" of steer over 4'. I sent the car into NPWDRL Man of the Mountain race in December 2013. It was my very first race and after 4 runs that car with 6" of steer that you would probably trash and start over set 2 track records. I will find the video link for you if you would like to see it. I raced that car in the novice class in 2014 and ended up third overall at the end of the season.
All I'm trying to say here is that yes you need some sort of baseline to start with weighting wise and steer wise and wheel gap wise, and make changes from that baseline, but just because a car has more than 2" of steer over 4' does not mean it has build issues. Drill jobs are different, each block of wood is different, how the car is shaped is different, the angle of the front dominate wheel is different from car to car, there are just to many variables in each build to just bluntly say a 6" steer car can't compete with a 2" steer car or that a 6" steer car has build issues. Don't give up on a car that takes more steer than you think it should, you will find that out as you build cars and gain more experience.
Also like you mentioned above, I bought a fully assembled car built by a top racer. I thought I could examine it, take notes and duplicate what this top builder had done. I have news for you, it does not happen, if it did everyone would be fast and contending for National Championships. I ended up with a car that was fast and a top contending car and made it dog slow. As hard as I tried even though I took notes on how the car was set up, I could not prep it like it was or get it back together and duplicate what that racer had done even though I had all of the information to do so. A top racer could give everything he does on his winning car, and just because it works for him does not mean it will work for you. You will discover this as you build a car and try to duplicate what others are doing.
I look forward to racing against you in up coming races.
Steve - Mister B
Great post Steve /images/boards/smilies/thumb.gif
If not 12x12...What was the weight placement in 2nd hand Smoke?...cool name btw.
My issue with a lot of steer is something is ultimately causing it, it doesn't just happen.There are forces being applied that are different than for the 2" steer car, and those forces are devouring the finite amount of energy the car has.
Think of it this way...you and I build two absolutely identical cars, both are capable of running straight down the track without ever touching a rail. If we raced we would be nearly tie every round. Now take your car and induce even a modest 1" steer, I will beat you every time. With a 2" steer I will beat you by even more, a 3" steer even further. If I induce a 1" steer to my car, and your identical car is running 2" of steer, I will also beat you every time. Steer takes energy, unless the energy loss is being positively offset elsewhere, the higher steer car will always lose.
Can it be that the net result of a 6" steer makes for a quicker car, yes...but it has to be made up somewhere else. This is where a bigger motor or synergy factor in. In your case synergy because by your admission you didn't start with one of the biggest motors possible, and why you probably wont post the weight placement of your car.
If you bought a top car and did not duplicate its results, you didn't truly duplicate the car, you missed something. Physics doesn't know if Kinser built the car, or if you or I did. Do you truly believe if you were sitting at a table with Kinser, JDB, QT, HurriCrane , Gravity, and other top builders giving you step by step instructions of how they build their cars, that you could not build a car equal to theirs?....what part could you not duplicate?
I'm hoping I can send in a somewhat competitive car for June or July...I feel I need just a few more of the "secrets" to run against the top builders without totally humiliating myself. Going off of my track I am a good .025 or more behind the better times, I'm not sure if the times will be better or worse when running on the same track, but there is only one way to find out.
If not 12x12...What was the weight placement in 2nd hand Smoke?...cool name btw.
My issue with a lot of steer is something is ultimately causing it, it doesn't just happen.There are forces being applied that are different than for the 2" steer car, and those forces are devouring the finite amount of energy the car has.
Think of it this way...you and I build two absolutely identical cars, both are capable of running straight down the track without ever touching a rail. If we raced we would be nearly tie every round. Now take your car and induce even a modest 1" steer, I will beat you every time. With a 2" steer I will beat you by even more, a 3" steer even further. If I induce a 1" steer to my car, and your identical car is running 2" of steer, I will also beat you every time. Steer takes energy, unless the energy loss is being positively offset elsewhere, the higher steer car will always lose.
Can it be that the net result of a 6" steer makes for a quicker car, yes...but it has to be made up somewhere else. This is where a bigger motor or synergy factor in. In your case synergy because by your admission you didn't start with one of the biggest motors possible, and why you probably wont post the weight placement of your car.
If you bought a top car and did not duplicate its results, you didn't truly duplicate the car, you missed something. Physics doesn't know if Kinser built the car, or if you or I did. Do you truly believe if you were sitting at a table with Kinser, JDB, QT, HurriCrane , Gravity, and other top builders giving you step by step instructions of how they build their cars, that you could not build a car equal to theirs?....what part could you not duplicate?
I'm hoping I can send in a somewhat competitive car for June or July...I feel I need just a few more of the "secrets" to run against the top builders without totally humiliating myself. Going off of my track I am a good .025 or more behind the better times, I'm not sure if the times will be better or worse when running on the same track, but there is only one way to find out.
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