I used to think that maximum wheelbase was the best way to go. The front wheel as far forward as possible would improve the straight line tracking which seems good. However, having the front wheel back a little shifts the weight back allowing for more energy. It also decreases the rotational inertia of the car itself making which translates into smaller losses of energy in the curved section of the track.
It seems that there may be best position that is not at max wheelbase. This may be a track dependent decision, rougher tracks may favor longer wheel base cars to keep straight tracking.
What do people feel is optimal front wheel location? I am guessing that about an inch back from the nose of the car is pretty good.
Front Wheel Location
Front Wheel Location
It's great when it goes straight.
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Stan Pope
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Re: Front Wheel Location
I have promoted pushing the front wheels forward as far as possible. The situation improves if the front wheels are pulled back from that extreme to leave approx 20% (one ounce) of the weight on the front wheels. This movement does shift the CM location slightly, but is not the primary cause.
The reason for this choice is to keep the car stuck to the track, i.e. to prevent sideways sliding of the front wheels.
There are other energy considerations, such as minimizing the amount of energy needed to get a wheel over a bump in the road. Grandpa says that a shorter wheelbase is advantageous for this. I need to understand the process better before signing on.
The reason for this choice is to keep the car stuck to the track, i.e. to prevent sideways sliding of the front wheels.
There are other energy considerations, such as minimizing the amount of energy needed to get a wheel over a bump in the road. Grandpa says that a shorter wheelbase is advantageous for this. I need to understand the process better before signing on.
Stan
"If it's not for the boys, it's for the birds!"
"If it's not for the boys, it's for the birds!"
Re: Front Wheel Location
The issue of the front wheel sticking to the track and tracking straight is key. I think the rule of thumb from hard experience is 1 once of weight on the track. Also you want to leave your tool marks on the wheels to avoid slipping. I checked my physics text for mechanical losses and slipping is one of them. A long wheelbase creates a longer turning radius helping with the alignment of the car.
Ever thought of putting a spoiler on the front to create a down force at speed so you could maybe put a little more weight in the back to generate more energy? Perhaps this is just another bad idea to be crossed off and put into the flawed concept pile. Still you might be able to get away with .8 ounce of weight up front. You could use an adjustable fore and aft weight on a screw and put your front spoiler on a pivot point to investigate this possibility?
Perhaps it would be interesting to consider moving the raised wheel back an inch or two. This would improve the rotational inertia of the car somewhat and when the wheel hits the center rail there may be less losses. A radical design might be all four wheels asymmetrically placed in the body to optimize inertia, straight tracking, and bump/vibration losses.
Ever thought of putting a spoiler on the front to create a down force at speed so you could maybe put a little more weight in the back to generate more energy? Perhaps this is just another bad idea to be crossed off and put into the flawed concept pile. Still you might be able to get away with .8 ounce of weight up front. You could use an adjustable fore and aft weight on a screw and put your front spoiler on a pivot point to investigate this possibility?
Perhaps it would be interesting to consider moving the raised wheel back an inch or two. This would improve the rotational inertia of the car somewhat and when the wheel hits the center rail there may be less losses. A radical design might be all four wheels asymmetrically placed in the body to optimize inertia, straight tracking, and bump/vibration losses.
It's great when it goes straight.
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gpraceman
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Re: Front Wheel Location
What you may gain by pushing the front end down aerodynamically will also have a horizontal vector component that will serve to slow the car down. Just having the weight there instead will let gravity do the job of stabilizing the front end without the loss of speed due to air resistance.Jewel wrote:Ever thought of putting a spoiler on the front to create a down force at speed so you could maybe put a little more weight in the back to generate more energy? Perhaps this is just another bad idea to be crossed off and put into the flawed concept pile. Still you might be able to get away with .8 ounce of weight up front. You could use an adjustable fore and aft weight on a screw and put your front spoiler on a pivot point to investigate this possibility?
Randy Lisano
Romans 5:8
Awana Grand Prix and Pinewood Derby racing - Where a child, an adult and a small block of wood combine for a lot of fun and memories.
Romans 5:8
Awana Grand Prix and Pinewood Derby racing - Where a child, an adult and a small block of wood combine for a lot of fun and memories.
Re: Front Wheel Location
Nice point.
It seems like a problematic idea. If you have .8 ounces on your front wheel and generate .2 ounces of down force, you may be able to get .2 ounces of weight further up the hill, which may over come the greater air resistance. You basically want to achieve performance something like a 5.2 ounce car. Their are tradeoffs involved but the higher energy may be greater than the air resistance, in that case it may be a good trade off.
It seems like a problematic idea. If you have .8 ounces on your front wheel and generate .2 ounces of down force, you may be able to get .2 ounces of weight further up the hill, which may over come the greater air resistance. You basically want to achieve performance something like a 5.2 ounce car. Their are tradeoffs involved but the higher energy may be greater than the air resistance, in that case it may be a good trade off.
It's great when it goes straight.
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gpraceman
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Re: Front Wheel Location
There is probably some break even point where you may gain some benefit, but it has been too many years since I used all of those formulas to calculate those type of things to determine where that point would be. There are so many other variables that come into play as well (besides a rusty brain).Jewel wrote:Nice point.
It seems like a problematic idea. If you have .8 ounces on your front wheel and generate .2 ounces of down force, you may be able to get .2 ounces of weight further up the hill, which may over come the greater air resistance. You basically want to achieve performance something like a 5.2 ounce car. Their are tradeoffs involved but the higher energy may be greater than the air resistance, in that case it may be a good trade off.
Maybe GrandPa or Michael Lastufka could be of help (I think we have to drag these guys into the forum
). I'm not sure about GrandPa, but Michael has an excuse, his daughter is helping out with a NASA experiment for the shuttle, and he has other things on his slate.Randy Lisano
Romans 5:8
Awana Grand Prix and Pinewood Derby racing - Where a child, an adult and a small block of wood combine for a lot of fun and memories.
Romans 5:8
Awana Grand Prix and Pinewood Derby racing - Where a child, an adult and a small block of wood combine for a lot of fun and memories.
Re: Front Wheel Location
Am I correct to surmise that lifting one of the front wheels is a standard practice? I've done quite well with all 4 on the track but if 3 will make it faster I'm for it. How will this affect performance on an edge guided track?(Supertrack) I generally put my front axle hole approx 1" from the front edge of the car which definitely improved directional stability on a rough (AWANA Catalog plans) track.
TIA
TIA
Awana Commander
Jeep Fleet Maintenance Director
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Bowhunter
I can't break the rules, I write them!
Jeep Fleet Maintenance Director
Dad
Bowhunter
I can't break the rules, I write them!
Re: Front Wheel Location
Three wheels are faster for a number of reasons.
The most important reason is that your car only has to accelerate 3 masses so it gains speed faster. A key concept is to reduce total rotational inertia, faster accleration means more speed at the bottom of the hill. Some folks consider the fly wheel effect, having more mass in the wheels, this idea may make the car roll farther, but it will act against speed.
Secondly, you cannot get all four wheels touching the tracking perfectly, this creates a car that will teter back and fourth to so some extent.
Thridly, it is easier to make the car go straight with one dominant wheel doing all the steering.
Most pine people go for three wheels. I have lost races going four wheels, and comeback and won going with three.
The most important reason is that your car only has to accelerate 3 masses so it gains speed faster. A key concept is to reduce total rotational inertia, faster accleration means more speed at the bottom of the hill. Some folks consider the fly wheel effect, having more mass in the wheels, this idea may make the car roll farther, but it will act against speed.
Secondly, you cannot get all four wheels touching the tracking perfectly, this creates a car that will teter back and fourth to so some extent.
Thridly, it is easier to make the car go straight with one dominant wheel doing all the steering.
Most pine people go for three wheels. I have lost races going four wheels, and comeback and won going with three.
It's great when it goes straight.
