Why all the added weight in setups??
09-09-2011, 03:56 PM
#167
Let me sum this thread up.
Mechanical weight does effect the handling negatively on paper.
The fact of the matter is, weight can make the car easier to drive. It's WAY easier to plug weights into a car in the right spots to settle it down than breaking out charts and spending weeks testing spring rates mixed with oil weight, piston hole sizing, pre-loads, anti-squat and on and on and on just to get a good minimum weight setup.
Think about it, we're driving a tiny, super fast go kart on dirt from a distance and expect to react and "feel" the car.....pfft, you just can get that in tune with a vehicle you have no physical connetion with.
Adding weight is like driving a 1/10 buggy and then picking up your SCT with 17.5, it feels like your in slow motion and you can drive the S!*t out of it.
Light + offroad is difficult, it's technically faster on paper but definitely not in my hands. Same reason I blow out my laptimes when I grab more motor then a 13.5.
Use the weight, learn the car and then work on lightening it up when you peak in lap times. Chances are you'll get quicker. Can i get an AMEN.
Mechanical weight does effect the handling negatively on paper.
The fact of the matter is, weight can make the car easier to drive. It's WAY easier to plug weights into a car in the right spots to settle it down than breaking out charts and spending weeks testing spring rates mixed with oil weight, piston hole sizing, pre-loads, anti-squat and on and on and on just to get a good minimum weight setup.
Think about it, we're driving a tiny, super fast go kart on dirt from a distance and expect to react and "feel" the car.....pfft, you just can get that in tune with a vehicle you have no physical connetion with.
Adding weight is like driving a 1/10 buggy and then picking up your SCT with 17.5, it feels like your in slow motion and you can drive the S!*t out of it.
Light + offroad is difficult, it's technically faster on paper but definitely not in my hands. Same reason I blow out my laptimes when I grab more motor then a 13.5.
Use the weight, learn the car and then work on lightening it up when you peak in lap times. Chances are you'll get quicker. Can i get an AMEN.
09-09-2011, 04:03 PM
#168
A M E N
09-09-2011, 04:09 PM
#169
Tech Regular
Thread Starter
If you want a full size vehicle with a power to weight ratio similar to an RC car to base your comparisons.....
http://www.arielatom.com/specs/atom-500-v8
roughly .45 HP per pound.
http://www.arielatom.com/specs/atom-500-v8
roughly .45 HP per pound.
09-09-2011, 08:09 PM
#170
http://hyperphysics.phy-astr.gsu.edu/hbase/frict.html
Frictional resistance to the relative motion of two solid objects is usually proportional to the force which presses the surfaces together as well as the roughness of the surfaces. Since it is the force perpendicular or "normal" to the surfaces which affects the frictional resistance, this force is typically called the "normal force" and designated by N. The frictional resistance force may then be written:
The premise that several other users are trying to make (and failing, btw) is that the weight isn't "free", as you have to pay a price to drag that extra ballast around the track via (insert all the bad things that happen when you are heavy here).
The problem we have on this thread is nobody has quantified when the tradeoff between the extra ballast and grip is. And I doubt very much anyone here is going to answer that one.
Well, one guy got it close and I busted him up for it, but what the heck.
09-10-2011, 06:01 AM
#171
Personally I don't run that much weight in my cars. Everyone seems to be comparing are little toys to 1:1 race cars, well in most case real race cars have a minimum weight they have to meet and its car in full race trim minus driver. Example Nascar minimum weight is 3400 lbs. this weight includes everything but the driver. So when the driver gets in the car you now have added about 200 lbs to the car. They do count for this when they setup the car, that the drivers weight will not throw off the balance. While Tebo may run 27g in the front of his car, I only run 20g and my son only has about 7g in the front of his but he only runs a 17.5. So if you want to add weight then add it if not then don't, Just have fun racing!
09-10-2011, 08:42 AM
#172
It has been adequately explained a number of ways. Just because some don't understand does not mean the explanations don't make sense.
09-10-2011, 02:22 PM
#173
Tech Adept
Let me sum this thread up.
Mechanical weight does effect the handling negatively on paper.
The fact of the matter is, weight can make the car easier to drive. It's WAY easier to plug weights into a car in the right spots to settle it down than breaking out charts and spending weeks testing spring rates mixed with oil weight, piston hole sizing, pre-loads, anti-squat and on and on and on just to get a good minimum weight setup.
Think about it, we're driving a tiny, super fast go kart on dirt from a distance and expect to react and "feel" the car.....pfft, you just can get that in tune with a vehicle you have no physical connetion with.
Adding weight is like driving a 1/10 buggy and then picking up your SCT with 17.5, it feels like your in slow motion and you can drive the S!*t out of it.
Light + offroad is difficult, it's technically faster on paper but definitely not in my hands. Same reason I blow out my laptimes when I grab more motor then a 13.5.
Use the weight, learn the car and then work on lightening it up when you peak in lap times. Chances are you'll get quicker. Can i get an AMEN.
Mechanical weight does effect the handling negatively on paper.
The fact of the matter is, weight can make the car easier to drive. It's WAY easier to plug weights into a car in the right spots to settle it down than breaking out charts and spending weeks testing spring rates mixed with oil weight, piston hole sizing, pre-loads, anti-squat and on and on and on just to get a good minimum weight setup.
Think about it, we're driving a tiny, super fast go kart on dirt from a distance and expect to react and "feel" the car.....pfft, you just can get that in tune with a vehicle you have no physical connetion with.
Adding weight is like driving a 1/10 buggy and then picking up your SCT with 17.5, it feels like your in slow motion and you can drive the S!*t out of it.
Light + offroad is difficult, it's technically faster on paper but definitely not in my hands. Same reason I blow out my laptimes when I grab more motor then a 13.5.
Use the weight, learn the car and then work on lightening it up when you peak in lap times. Chances are you'll get quicker. Can i get an AMEN.
I get about the same results when I play around with adding weight. I try to run my cars light as I can. Then use a little weight in one end or the other if it needs to calm down a little. For me it feels like a little weight makes that end of the car feel a little more stable. It's a fine line though, to much makes it feel as if that end resists what I want it to do. Usually a half onuce to an once is plenty. But I have used more before. It's just a little easier and quicker than testing shock setups. I usually find one that works for me and go a little lighten the oil a little if the track is blown out or up the oil if it's pretty smooth. To each his own I guess. I work alot in different areas and there isn't always a track close by or time to make it, but when I do get the chance I like to show up and blow up kinda deal. Just run the crap out of my rigs for practice and racing to just relax. Not really into wrenching a bunch if it ain't broke.
09-10-2011, 02:47 PM
#174
Tech Addict
Let me sum this thread up.
Mechanical weight does effect the handling negatively on paper.
The fact of the matter is, weight can make the car easier to drive. It's WAY easier to plug weights into a car in the right spots to settle it down than breaking out charts and spending weeks testing spring rates mixed with oil weight, piston hole sizing, pre-loads, anti-squat and on and on and on just to get a good minimum weight setup.
Think about it, we're driving a tiny, super fast go kart on dirt from a distance and expect to react and "feel" the car.....pfft, you just can get that in tune with a vehicle you have no physical connetion with.
Adding weight is like driving a 1/10 buggy and then picking up your SCT with 17.5, it feels like your in slow motion and you can drive the S!*t out of it.
Light + offroad is difficult, it's technically faster on paper but definitely not in my hands. Same reason I blow out my laptimes when I grab more motor then a 13.5.
Use the weight, learn the car and then work on lightening it up when you peak in lap times. Chances are you'll get quicker. Can i get an AMEN.
Mechanical weight does effect the handling negatively on paper.
The fact of the matter is, weight can make the car easier to drive. It's WAY easier to plug weights into a car in the right spots to settle it down than breaking out charts and spending weeks testing spring rates mixed with oil weight, piston hole sizing, pre-loads, anti-squat and on and on and on just to get a good minimum weight setup.
Think about it, we're driving a tiny, super fast go kart on dirt from a distance and expect to react and "feel" the car.....pfft, you just can get that in tune with a vehicle you have no physical connetion with.
Adding weight is like driving a 1/10 buggy and then picking up your SCT with 17.5, it feels like your in slow motion and you can drive the S!*t out of it.
Light + offroad is difficult, it's technically faster on paper but definitely not in my hands. Same reason I blow out my laptimes when I grab more motor then a 13.5.
Use the weight, learn the car and then work on lightening it up when you peak in lap times. Chances are you'll get quicker. Can i get an AMEN.
These are RC cars, we have no physical touch to them and have no seat of the pants feeling with them. We go by what we see with our senses really. Actually if you think about how we drive these things it's quite amazing that we can even drive them as fast as we do.
These are not real full scale cars. We do not have equipment to put these things through suspension test. We do not have access to the same thing the F1, Indy Car, NASCAR or any other touring series teams have access to.
How many people have 2 million dollars to spend on a 7-Post Rig to simulate their toy car on a track?
http://www.youtube.com/watch?v=f79D0...eature=related
http://www.youtube.com/watch?v=mBRSt...eature=related
Exactly like a thought, like no one. So I think we will all just just keep on doing what works for us.
09-10-2011, 03:57 PM
#175
Let me sum this thread up.
Mechanical weight does effect the handling negatively on paper.
The fact of the matter is, weight can make the car easier to drive. It's WAY easier to plug weights into a car in the right spots to settle it down than breaking out charts and spending weeks testing spring rates mixed with oil weight, piston hole sizing, pre-loads, anti-squat and on and on and on just to get a good minimum weight setup.
Think about it, we're driving a tiny, super fast go kart on dirt from a distance and expect to react and "feel" the car.....pfft, you just can get that in tune with a vehicle you have no physical connetion with.
Adding weight is like driving a 1/10 buggy and then picking up your SCT with 17.5, it feels like your in slow motion and you can drive the S!*t out of it.
Light + offroad is difficult, it's technically faster on paper but definitely not in my hands. Same reason I blow out my laptimes when I grab more motor then a 13.5.
Use the weight, learn the car and then work on lightening it up when you peak in lap times. Chances are you'll get quicker. Can i get an AMEN.
Mechanical weight does effect the handling negatively on paper.
The fact of the matter is, weight can make the car easier to drive. It's WAY easier to plug weights into a car in the right spots to settle it down than breaking out charts and spending weeks testing spring rates mixed with oil weight, piston hole sizing, pre-loads, anti-squat and on and on and on just to get a good minimum weight setup.
Think about it, we're driving a tiny, super fast go kart on dirt from a distance and expect to react and "feel" the car.....pfft, you just can get that in tune with a vehicle you have no physical connetion with.
Adding weight is like driving a 1/10 buggy and then picking up your SCT with 17.5, it feels like your in slow motion and you can drive the S!*t out of it.
Light + offroad is difficult, it's technically faster on paper but definitely not in my hands. Same reason I blow out my laptimes when I grab more motor then a 13.5.
Use the weight, learn the car and then work on lightening it up when you peak in lap times. Chances are you'll get quicker. Can i get an AMEN.
I doubt anyone could sum it up better...I'm going to print this out and put it in my notebook
...Racer53
09-10-2011, 08:11 PM
#176
back in the day.......
I had an RC10 well under 3 lbs ready to race....
It was wicked fast and fun, however being so light it was very difficult to tune so I rarely used it on anything but my home track.
Today I don't think I'd be as concerned with the weight. With Lipo's and brushless the horsepower is way higher than it was 20 years ago so weight as a "performance" issue to me is almost a non-issue to me in anything other than stock class.
With that said I would still hesitate to add weight if I could find another method of tuning my rig.
I had an RC10 well under 3 lbs ready to race....
It was wicked fast and fun, however being so light it was very difficult to tune so I rarely used it on anything but my home track.
Today I don't think I'd be as concerned with the weight. With Lipo's and brushless the horsepower is way higher than it was 20 years ago so weight as a "performance" issue to me is almost a non-issue to me in anything other than stock class.
With that said I would still hesitate to add weight if I could find another method of tuning my rig.
01-26-2012, 06:10 PM
#177
Parachute effect is not so much a factor of the truck as the driver not knowing how to jump a truck so I don't buy that one either. Get the nose down on the jump and it's not an issue.
Horsepower can overcome the mass durring acceleration but slowing down and changing directions can not be cured by more motor.
Most of the time spent is decelerating, setting up for and exiting a corner. If a car is lighter, it can carry more corner speed and accelerate faster with less HP.
The only valid excuse I have heard so far is from others at the track, weighting the truck is a defensive manuver to keep other heavy trucks from knocking you around in the corners.
AND A +1
01-27-2012, 06:59 PM
#178
The extra weight works because the cars are easier to drive. The power of rc cars has increased quite a bit in the last 4+ years due to higher voltage lipo and brushless motors.
An example from the on road side, on a carpet track where traction is not an issue. We were testing trans am cars, and every time we added weight the car went faster on the stop watch. Another group of guys racing trans am used to give "penalty weight" for victories but all it did was make the cars faster. Now, the tires for t/a cars are not the best ever, and the bodies are like shoeboxes, so they need some help.
On the other hand, an F1 car on foam tires racing on carpet goes faster the lighter you make it. At one point I went to an 1800 mAh mini revo battery weighing 96g and picked up about .3-4. sec a lap over a 200g full size lipo battery. That's because the car already has plenty of traction, and the wimpy 540 mabuchi motors don't put out much power.
On the other hand the same F1 car on the Tamiya USA track with the not so good Tamiya rubber tires is so much better with upwards of 5 oz (140g) added it is ridiculous. The amazing part is that tire wear was actually reduced with the extra weight. The car was not sliding and used the tires much better. Especially in a simple car like an F1, where there are not so many options for setup, weight can be a huge help.
Sure in an ideal world, the lighter car is always better. It seems like we have to make compromises since we are not in the cars, the power to weight is insane, and we can't take much weight off the unsprung parts.
And while everything a pro driver does shouldn't be taken as gospel, when everybody is doing the same thing and it's working, it shouldn't be dismissed out of hand because it's not "right".
An example from the on road side, on a carpet track where traction is not an issue. We were testing trans am cars, and every time we added weight the car went faster on the stop watch. Another group of guys racing trans am used to give "penalty weight" for victories but all it did was make the cars faster. Now, the tires for t/a cars are not the best ever, and the bodies are like shoeboxes, so they need some help.
On the other hand, an F1 car on foam tires racing on carpet goes faster the lighter you make it. At one point I went to an 1800 mAh mini revo battery weighing 96g and picked up about .3-4. sec a lap over a 200g full size lipo battery. That's because the car already has plenty of traction, and the wimpy 540 mabuchi motors don't put out much power.
On the other hand the same F1 car on the Tamiya USA track with the not so good Tamiya rubber tires is so much better with upwards of 5 oz (140g) added it is ridiculous. The amazing part is that tire wear was actually reduced with the extra weight. The car was not sliding and used the tires much better. Especially in a simple car like an F1, where there are not so many options for setup, weight can be a huge help.
Sure in an ideal world, the lighter car is always better. It seems like we have to make compromises since we are not in the cars, the power to weight is insane, and we can't take much weight off the unsprung parts.
And while everything a pro driver does shouldn't be taken as gospel, when everybody is doing the same thing and it's working, it shouldn't be dismissed out of hand because it's not "right".
01-27-2012, 07:36 PM
#179
The extra weight works because the cars are easier to drive. The power of rc cars has increased quite a bit in the last 4+ years due to higher voltage lipo and brushless motors.
An example from the on road side, on a carpet track where traction is not an issue. We were testing trans am cars, and every time we added weight the car went faster on the stop watch. Another group of guys racing trans am used to give "penalty weight" for victories but all it did was make the cars faster. Now, the tires for t/a cars are not the best ever, and the bodies are like shoeboxes, so they need some help.
On the other hand, an F1 car on foam tires racing on carpet goes faster the lighter you make it. At one point I went to an 1800 mAh mini revo battery weighing 96g and picked up about .3-4. sec a lap over a 200g full size lipo battery. That's because the car already has plenty of traction, and the wimpy 540 mabuchi motors don't put out much power.
On the other hand the same F1 car on the Tamiya USA track with the not so good Tamiya rubber tires is so much better with upwards of 5 oz (140g) added it is ridiculous. The amazing part is that tire wear was actually reduced with the extra weight. The car was not sliding and used the tires much better. Especially in a simple car like an F1, where there are not so many options for setup, weight can be a huge help.
Sure in an ideal world, the lighter car is always better. It seems like we have to make compromises since we are not in the cars, the power to weight is insane, and we can't take much weight off the unsprung parts.
And while everything a pro driver does shouldn't be taken as gospel, when everybody is doing the same thing and it's working, it shouldn't be dismissed out of hand because it's not "right".
An example from the on road side, on a carpet track where traction is not an issue. We were testing trans am cars, and every time we added weight the car went faster on the stop watch. Another group of guys racing trans am used to give "penalty weight" for victories but all it did was make the cars faster. Now, the tires for t/a cars are not the best ever, and the bodies are like shoeboxes, so they need some help.
On the other hand, an F1 car on foam tires racing on carpet goes faster the lighter you make it. At one point I went to an 1800 mAh mini revo battery weighing 96g and picked up about .3-4. sec a lap over a 200g full size lipo battery. That's because the car already has plenty of traction, and the wimpy 540 mabuchi motors don't put out much power.
On the other hand the same F1 car on the Tamiya USA track with the not so good Tamiya rubber tires is so much better with upwards of 5 oz (140g) added it is ridiculous. The amazing part is that tire wear was actually reduced with the extra weight. The car was not sliding and used the tires much better. Especially in a simple car like an F1, where there are not so many options for setup, weight can be a huge help.
Sure in an ideal world, the lighter car is always better. It seems like we have to make compromises since we are not in the cars, the power to weight is insane, and we can't take much weight off the unsprung parts.
And while everything a pro driver does shouldn't be taken as gospel, when everybody is doing the same thing and it's working, it shouldn't be dismissed out of hand because it's not "right".
The traction from a rubber tire is NOT linear with respect to the force on the tire. The different scenarios you mention happen to be on different parts of a complicated relationship/curve. Sometime we are on the short side of ideal. Obviously with too much weight we are then on the other side of optimum.
This is the same reason why anti-sway bars work. If the tire coefficient of friction was linear, anti-sway bars would not change understeer/oversteer. They exploit the rubber non-linearity to achieve the effect.
How do I know? Nearly 30 years in rubber and full scale power train engineering, much of it on suspension, for a good chunk of the worlds automakers. I routinely work with wheel force data and such.
So yes, it is quite possible for added weight to make the car faster despite it’s increased mass, all supported by quite straightforward physics. Just not simplified physics.
01-27-2012, 08:29 PM
#180
Thank you.
Good post. What you are describing, some others have touched on to various degrees, is a significant piece of the puzzle.
The traction from a rubber tire is NOT linear with respect to the force on the tire. The different scenarios you mention happen to be on different parts of a complicated relationship/curve. Sometime we are on the short side of ideal. Obviously with too much weight we are then on the other side of optimum.
This is the same reason why anti-sway bars work. If the tire coefficient of friction was linear, anti-sway bars would not change understeer/oversteer. They exploit the rubber non-linearity to achieve the effect.
How do I know? Nearly 30 years in rubber and full scale power train engineering, much of it on suspension, for a good chunk of the worlds automakers. I routinely work with wheel force data and such.
So yes, it is quite possible for added weight to make the car faster despite it’s increased mass, all supported by quite straightforward physics. Just not simplified physics.
The traction from a rubber tire is NOT linear with respect to the force on the tire. The different scenarios you mention happen to be on different parts of a complicated relationship/curve. Sometime we are on the short side of ideal. Obviously with too much weight we are then on the other side of optimum.
This is the same reason why anti-sway bars work. If the tire coefficient of friction was linear, anti-sway bars would not change understeer/oversteer. They exploit the rubber non-linearity to achieve the effect.
How do I know? Nearly 30 years in rubber and full scale power train engineering, much of it on suspension, for a good chunk of the worlds automakers. I routinely work with wheel force data and such.
So yes, it is quite possible for added weight to make the car faster despite it’s increased mass, all supported by quite straightforward physics. Just not simplified physics.
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
