Quote:
Originally Posted by AntH
Here's a challenge for you. Name any other form of Motorsport apart from tractor pulling where adding weight is considered a good idea. You can include any other form of RC racing in that too. 1/8th OR, no , any on road class, no. Post up a list.
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Can you name any other form of motorsport comparable to off road RC racing, or RC racing in general? I can't think of any series where a base chassis is produced that incorporates a multitude of layouts for various engines, gearboxes, steering layouts etc. Full size racing cars can be designed from the outset to have a perfect, or near enough perfect given the design limitations, weight distribution for the components involved. Imbalances from front to rear can be tuned out with aerodynamic adjustments. Stacking weight is a hindrance because the amount of weight required to make a difference to the weight distribution of the car would ruin the car's handling, and you're very right with your observation of increasing the roll moment.
However, your argument is very black and white, and I've seen you mention "flaky science" in several posts - but you don't seem to be applying the theory correctly. By the same logic, we should never use wings because of the drag they generate. You're right in pointing out the negative impacts adding weight can have from a physics standpoint, but with an RC car, the driver is never connected to the car physically. You drive through visual feel and the confidence you get from the car. Adding 50 grams might mean the car will lose 0.1 mid-corner in perfect conditions, but if it's the difference between a driver turning in and feeling the car float, and then a driver turning in and feeling his car much more planted and stable, the driver is going to be able to pull out more time over a 5 minute run than is lost with the added weight.
With regards to the idea that suspension tuning is the answer to all stability issues, you again seem to have a very black and white idea of how the car performs. 2wd buggies will never have perfect weight distributions out of the box. It would be nice if they all did, because it would mean that we could all install electronics of a specific weight in a specific place and end up with a perfectly balanced car, but that's not how cars are designed. If you go up in size on your front pistons to cope with one bump better, you might get the car riding the same over that bump as if you dropped 25 grams under the servo. Great - it handles that one bump better. What about the other 10 corners on the track that might be very high grip and smooth? You'd want a firmer front end for that, but you've just sacrificed a cumulative second or two by gaining a tiny bit of stability over one bump. You can't say there's one clear-cut solution that suits every car on every track, and in constantly trying to adjust your shock setup to find a better balance for the track and conditions you'd be chasing your tail. I understand why you're thinking what you're thinking - but you're thinking in terms of ideals, and that's just not how you can set up an RC car. A chassis has virtually infinite possibilities for weight distribution within the confines of the kit layout, with speedos, motors, batteries, receivers and servos of differing weights, but it's very rare that you can position them in such a manner that the left/right and front/rear distribution produces a nicely balanced car. Weight isn't just an option if you're wanting to be competitive on a wide variety of tracks, it's virtually a necessity.
With regards to the RZ6 and B5 differences, the motor and battery being transverse on the Associated already puts the two heaviest things on the chassis further back than the Kyosho. It's little surprise they decided to run more brass up front than Tebo did. You can't compare them directly though, because they had different geometry with different front shock setups, different electronics placements, different chassis shapes, different plastic grades, different CGs, different screw mounting points so different flex characteristics, different alignment... saying "one didn't run as much weight as the other and it was faster over a lap so weight is useless" is very much specious reasoning.
It's interesting to see people come up with different theories, but to try and claim one thing has no benefits using one incorrectly applied theory, and subsequently rubbishing anyone who thinks the opposite (which seems to be every other driver or professional engineer on the planet) is a bit daft, to say the least.