HPI R40 Nitro Car Forum
07-01-2005, 10:34 PM
#7711
Originally Posted by Hesky
I think I can see your point, above all its the way the car handles that matters and if using a bendy chassis helps then it has to be done. just finding it hard to get my head around this 'controlled' chassis twisting, I mean 'scale' is the word here and when we're talking about suspension dynamics the SAME theory apples to 1:1, 1:5, 1:10 just as aerodynamics does hence why there are scale aerodynamic test tunnels for motor racing.
With regards to F1 cars I'm guessing when you talk of flex you mean the anti-roll bar or torsion spring passing trough the middle bell crank linkage fixed to the chassis, these bars serve a different purpose much like the sway bar of our rc cars. This bar has nothing to do with spring rate, and has a different effect on handling than a bendy chassis. F1 chassis are as rigid as they come! really the only components that compress or flex on an f1 car are the spring's, the arb's and tires. these bar the tires are easy to CONTROL,the chassis is much harder to measure, rate and adjust so this is why its not designed to flex and its is not really desirable when they do so.
With regards to F1 cars I'm guessing when you talk of flex you mean the anti-roll bar or torsion spring passing trough the middle bell crank linkage fixed to the chassis, these bars serve a different purpose much like the sway bar of our rc cars. This bar has nothing to do with spring rate, and has a different effect on handling than a bendy chassis. F1 chassis are as rigid as they come! really the only components that compress or flex on an f1 car are the spring's, the arb's and tires. these bar the tires are easy to CONTROL,the chassis is much harder to measure, rate and adjust so this is why its not designed to flex and its is not really desirable when they do so.
I was talking about the 2004 Ferrari which I believe did away with springs altogether at one point and used the flex in the actual front suspension rods as the "springs" rather than using a sprung damper unit. I could be wrong and cant find the magazine I read this in, but I recall the concept being something like the rear end of a 1/12 scale rc car just in the front suspension. 1/12 is another example of when a chassis flex is used as a suspension component of the vehicle
I was not comparing our cars to f1 cars, but you are spot on scale is the word here. Certain things just dont scale. Our cars in full size would weigh 17kg for example and have 15 horsepower. Air does NOT scale, the molecules remain the same size, the aero on our cars is quite different to full size aero. This info comes from some VERY VERY reliable sources.
07-01-2005, 10:48 PM
#7712
Anyway I am not trying to be a dick but point is you can use the inherent flex in the chassis to your advantage and I have. Examples:
I recently got a 2005 edition pro 4 with a 2.0mm (down from 2.5mm) bottom deck and a 2.25 mm more flexible top deck. I also removed the centre brace post. On a high grip asphalt track using foam I was .3 seconds faster and also more consistent.
On a very fast high grip asphalt track I installed the graphite arms on my R40 and went 1 second (!) per lap quicker, now I am onto the front runner pace. So stiffening can work to your advantage, just need to use it in the right way.
I recently got a 2005 edition pro 4 with a 2.0mm (down from 2.5mm) bottom deck and a 2.25 mm more flexible top deck. I also removed the centre brace post. On a high grip asphalt track using foam I was .3 seconds faster and also more consistent.
On a very fast high grip asphalt track I installed the graphite arms on my R40 and went 1 second (!) per lap quicker, now I am onto the front runner pace. So stiffening can work to your advantage, just need to use it in the right way.
07-01-2005, 11:20 PM
#7713
Its funny your hear of rc manufactures speak of ultra stiff chassis platforms and on the other hand you get random yokos with a spring on the top deck like my old yr4. I guess suck it and see is the best bet. as racers I guess being quick is better than stuff making sense. 
about rc aerodynamics what your saying is correct the air molecules are a constant but there size is minute so the differing influences they will have on a 10th scale car when compared to a full scale will be negligible near nothing, yes the factors are multiplied but it is fully calculable and the principles of course are the same. The aero on a full size car is the same as that of an rc car it is simply multiplied by a set factor but has identical influences.
I know what you mean about power output and weight I guess a mathematician could explain why our 1:10th rc cars dont scale in that respect. Its all about the math
about rc aerodynamics what your saying is correct the air molecules are a constant but there size is minute so the differing influences they will have on a 10th scale car when compared to a full scale will be negligible near nothing, yes the factors are multiplied but it is fully calculable and the principles of course are the same. The aero on a full size car is the same as that of an rc car it is simply multiplied by a set factor but has identical influences.
I know what you mean about power output and weight I guess a mathematician could explain why our 1:10th rc cars dont scale in that respect. Its all about the math
07-02-2005, 03:08 AM
#7714
Originally Posted by Hesky
Its funny your hear of rc manufactures speak of ultra stiff chassis platforms and on the other hand you get random yokos with a spring on the top deck like my old yr4. I guess suck it and see is the best bet. as racers I guess being quick is better than stuff making sense.
about rc aerodynamics what your saying is correct the air molecules are a constant but there size is minute so the differing influences they will have on a 10th scale car when compared to a full scale will be negligible near nothing, yes the factors are multiplied but it is fully calculable and the principles of course are the same. The aero on a full size car is the same as that of an rc car it is simply multiplied by a set factor but has identical influences.
I know what you mean about power output and weight I guess a mathematician could explain why our 1:10th rc cars dont scale in that respect. Its all about the math
about rc aerodynamics what your saying is correct the air molecules are a constant but there size is minute so the differing influences they will have on a 10th scale car when compared to a full scale will be negligible near nothing, yes the factors are multiplied but it is fully calculable and the principles of course are the same. The aero on a full size car is the same as that of an rc car it is simply multiplied by a set factor but has identical influences.
I know what you mean about power output and weight I guess a mathematician could explain why our 1:10th rc cars dont scale in that respect. Its all about the math
Anyway by all means try stuff out, but also be open to things which "should not" work like playing with chassis rigidity.
07-02-2005, 04:21 AM
#7715
Originally Posted by AMGRacer
Yep if you like it knock yourself out I hope it works out for you. My experiences are very opposite to what you are saying is all, take that with a grain of salt.
07-02-2005, 04:34 AM
#7716
Originally Posted by AMGRacer
You got it Harry. People can get too obsessed with an ultra stiff car. I have done it myself before today and what you can end up with is a car that is VERY VERY darty and extremely difficult to drive.
Im almost hoping my car does become darty. Cause them im going to tune to that and calm it. Also if it does get darty thats becuase its doing its job.
Now its almost like a personal setup. Some like this , some like that. Some oversteer , understeer and some nuetral.
Once I tune the car to the brace if it does get darty. The suspension should have a more efficient platform to work off of. Rather then soak up A. Road bumps + B. Chassis Flex = work force. The extra work force has now been cut out and not only thats its not a secondary force acting upon it. Flex is just like sound waves or any other waves. It comes in and travels through the car. At a certain point youll hit a bump and the car will immediatly detect it with the suspension and expand or contract. While that bump hits a wave goes through the car and probably after the car has taken the bump the wave gets to the top and probably causes it to counter that wave.
Otherwise if the chassis was stiff. The wave would die as it couldnt keep flowing. Basically think of a wave in water , now freeze the lake. No wave.
No think of the car going over the water....just use your imaginary rc float tires. Going over all those changing waves. Now freeze the water , now drive on it. Thats essentially what removing flex does just the opposite. It makes your car that is flexy and freezes it so things arent moving like water aka waves over it.
Just how Ive come to know cars. Why I like stiff chassis. Im guessing though there is a point to where the suspension cannot act on all the bumps alone and perhaps the secondary waves or flex help counter the bumps better. In this case it sounds like the suspension on our cars could be better developed for super stiff chassis platforms.
So with a little cost cutting they probably did envelope tuning towards using a more flexy chassis base.
But sounds like the pros dont use it and im sure there is some sort of handling or feeling that makes it worth to keep it stock. Even with all sorts of knowledge when it comes to full vehicle tweaking its still sometimes black magic.
Ask the formula 1 camps.
07-02-2005, 05:15 AM
#7717
Tech Elite
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this thread is getting to be better than the 710 thread(and thats a compliment).....the more people we get running the r40,and the better we run it as racers,maybe we can get HPI to keep on developing the car....
07-02-2005, 07:36 AM
#7718
Anyone care to share how tight/loose their gear mesh is??? I just added added a new engine to mine (bought the chassis used) and the gear mesh looked a little tight...
I look thru the manual and they have nothing in there...I know with electric cars, you want a little "play" in the gear mesh - but what about nitro??
I look thru the manual and they have nothing in there...I know with electric cars, you want a little "play" in the gear mesh - but what about nitro??
07-02-2005, 11:07 AM
#7720
Originally Posted by Artificial-I
No think of the car going over the water....just use your imaginary rc float tires. Going over all those changing waves. Now freeze the water , now drive on it. Thats essentially what removing flex does just the opposite. It makes your car that is flexy and freezes it so things arent moving like water aka waves over it.
Originally Posted by Artificial-I
In this case it sounds like the suspension on our cars could be better developed for super stiff chassis platforms.
Its pretty cool that racers have come to compensate for things like this and are trying different braces, chassis etc to basically go faster. As fastharry says by experimenting and improving our cars ourself like this its only gonna entice HPI to keep on developing the car.
07-02-2005, 11:25 AM
#7721
Yeah my guess is there is some bonus from the flex or what im thinking is its twisting. Im guessing some sort of torsional twist allows the car to track better. Kinda like an animal with a spine. It can now turn/angle a tad bit to enhance the turn... Kinda like a car thats been bent. It will go one way much easier. With the twist it can go either way and go back to center so your not driving a car that goes in circles.
This is just my guess of whats possibly happening when you allow the car to twist at that point.
Im sure something or other like that is going on and I guess otherwise the car is now like a 2 piece car. While when im using the aluminum its now a one piece chassis. In which that could be right in which its not good. Basically like a single linked suspension vs a multi-link or independant suspension. So I can see how this is something you want to have aflex in.
I also have a feeling hara and the rest are addicted to weight savings. So they probably only use something when really beneficial otherwise its a weight gain and I even know thats not good for suspensions as it now has to lift more up and down.
When you lighten your car it benefits many ways. Acceleration , Braking , Turning all enhanced. Even wear is reduced normally. Even engine wear!
The list of benefits from a lightweight car is insane. But even that some people say comes to a point to where too light of a chassis will not drive good. But even though it may stop driving good. It will go faster and faster , easier , use less gas , cooler engine....on and on and on.
So I definently wont be adding this part unless its way worth it and im already kinda decided its no good. But if I dont notice anything bad Ill probably just stick with it...cause its just so darn pretty. LOL.
This is just my guess of whats possibly happening when you allow the car to twist at that point.
Im sure something or other like that is going on and I guess otherwise the car is now like a 2 piece car. While when im using the aluminum its now a one piece chassis. In which that could be right in which its not good. Basically like a single linked suspension vs a multi-link or independant suspension. So I can see how this is something you want to have aflex in.
I also have a feeling hara and the rest are addicted to weight savings. So they probably only use something when really beneficial otherwise its a weight gain and I even know thats not good for suspensions as it now has to lift more up and down.
When you lighten your car it benefits many ways. Acceleration , Braking , Turning all enhanced. Even wear is reduced normally. Even engine wear!
The list of benefits from a lightweight car is insane. But even that some people say comes to a point to where too light of a chassis will not drive good. But even though it may stop driving good. It will go faster and faster , easier , use less gas , cooler engine....on and on and on.
So I definently wont be adding this part unless its way worth it and im already kinda decided its no good. But if I dont notice anything bad Ill probably just stick with it...cause its just so darn pretty. LOL.
07-02-2005, 12:57 PM
#7723
Hey guys. How do you get the clutch to engage earlier / later?
I never had to mess with it until now. Also what shoe do you reccomend. I see people saying the black slips.
Im having trouble engaging now. I have to get really high to get anything.
I never had to mess with it until now. Also what shoe do you reccomend. I see people saying the black slips.
Im having trouble engaging now. I have to get really high to get anything.
Last edited by Artificial-I; 07-02-2005 at 01:19 PM.
07-02-2005, 02:53 PM
#7724
Tech Initiate
I see people are using the Mugen Grey Shoe for the clutch...... and the Mugen Super Hard Spring too......