Originally Posted by
fyrstormer
Physics doesn't scale.
Of course Physics scale
... they have whole series' of classes they teach in physics at school about scaling laws and how to apply them. They may not always be simple as 1+1 but they do scale!
Originally Posted by
fyrstormer
It doesn't matter how 1:1 race cars are engineered, because 1:1 race cars have hundreds, if not thousands, of pounds of frame and drivetrain parts outside the engine bay, and that will always represent the vast majority of the vehicle's weight, whereas a 1:10 FWD touring car will be about evenly split between the weight of the motor/front gearbox vs. the entire rest of the chassis, assuming it uses a carbon-fiber double-deck chassis. Moving the motor is fine-tuning for a 1:1 race car, but it has an ENORMOUS effect on a 1:10 touring car.
Simple response - bollocks. Complicated response - The motor in the average 1:10 car represents about 12% of the total mass of car RTR. I've not weighted a 1:10 RC gearbox lately but I doubt it would be anymore than half of the motor weight (since you say the frame etc is separate I am only including the rotating parts of the gearbox) so even using that as a basis the motor and gearbox would equate to around 17% of the total car weight.
In 1:1 (depending on which series you base it on but since we are comparing TC), its hard to find specifics as a lot of racing people are pretty secretive, but even the bespoke (and therefore light) engines/gearboxes used in DTM still represent around 16% of the total car weight. For other categories, such as V8SC in Australia, it can be as high as 19% of the total weight. So your assertion that the motor and gearbox in a 1:10 car is considerably more of the proportional weight compared to a 1:1 car is not just flawed it is incorrect and therefore any claims you make based on that assertion are also incorrect.
Of course I am basing all this on the rules I have to run to here in Australia. You may run to different rules and this may skew this slightly but not significantly enough to change my point.
The biggest issue with gaining traction in a FWD (or any layout for that matter) 1:10 car is down to 2 things - power and weight transfer/balance. It is extremely difficult to make a FWD drive car transfer the weight back onto the driving wheels when the weight of the motor, and even the effects of its rotation, are trying to force the suspension to do the exact opposite. Some cars try to use this leverage to "increase" traction but they tend to have more issues in fast corners as the weight hanging so far forward changes the characteristics of the grip/slip circle and the front wheels simply lose grip sooner. Moving weight over the centreline of driving wheels is one of the holy grail's of chassis design and its no different in 1:10 or 1:1, but just moving the motor with no thought to suspension dynamics and weight balances etc won't provide a miracle cure.
Originally Posted by
fyrstormer
My experience with FWD is that having the motor anywhere except in front of the front axle is disastrous because it's impossible to get any traction to accelerate with. (even with the motor overhanging the front axle it's still hard to get traction, hence the reason for the part-time-4WD car I built.)
Your part time 4WD car is simply "cheating" by using 4WD when its advantageous (under power out of a corner or off the start line) and then going 2WD the rest of the time. Its essentially a version of how we used to run all 4WD cars when we used a series of one-ways, before we realised that brakes were important too.
When mini classes first moved to lipos (and lower weight) a lot of people struggled with car balance and handling and it wasn't until they added the weight back they had lost from going to the lipo battery that they got on top of it again.
My experience is that time and again people underestimate the importance of the rear suspension in a FWD car. In a 1:10 FWD car the battery (which comprises around 14-15% of the total RTR weight btw) is placed in the middle or even towards the rear of the car so the rear suspension actually has a lot of influence on how the car turns and handles. The only time it's useless is under power as the front does almost everything.