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Ok, let's start working it out-
1) what track and width
2) motor configuration
3) gearbox layout

won't the car need to be direct drive (or close to it like a trackmaster or something 2 gear instead of 3 gear) in order to make the most of the limited voltage/power, like a pan car?

Charlie don't surf wrote:Ok, let's start working it out-
1) what track and width
2) motor configuration
3) gearbox layout

That's what would need to be figured out. Sized approx the same as current 2wd 1/10 buggies.

kaiser wrote:won't the car need to be direct drive (or close to it like a trackmaster or something 2 gear instead of 3 gear) in order to make the most of the limited voltage/power, like a pan car?

Motor kv rating x battery voltage gives you motor max rpm. With a lower voltage battery we'd need a higher kv motor to get the same rpm. Obviously we'd have to gear it very differently since the motor would have far less torque but we'd also be pushing around less weight. This is the whole point. How should it be approached?

kaiser wrote:won't the car need to be direct drive (or close to it like a trackmaster or something 2 gear instead of 3 gear) in order to make the most of the limited voltage/power, like a pan car?

Current roar rules state 3 gear reduction. You can have more but not less- you can however argue that the spur is the first reduction gear.

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i always wanted to build a car or buggy, with a similiar design to what the fully electric mercedes gullwing has, which is 4 motors at each wheel.. providing superior traction/handling.

if i had the time/money/know how, i would use 380 sized brushless motors at each wheel, with some type of direct motor to cvd to wheel hub system, instead of using gearboxes, and have 1 speed controller controlling all 4 wheels independently to adjust for traction and slippage. Problem here is designing the speed controller capable of doing all of this.. 4 speed controllers just wouldnt work, unless you had some sort of modified 5-6 channel reciever, allowing for basically a 4 channel combined control from the trigger, and the normal 1 channel steering with the wheel.

if direct drive, each of The Rear CVD's would have a built in slipper, sort of like the hotshot slipper shown below, which is inline with the shaft.
http://www.rc10talk.com/download/file.php?id=44113&mode=view

would probably use a HPI drift assist module also for steering control.
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXMVE1&P=7

i have thought about this for a while, the major holdback is a proper speed controller, and would it actually work the way it was designed to?

I actually like this idea a lot. Who cares if you're B4.1 can do 80 MPH down the back straight and jump a 60 ft. triple. I'd like to see the "slower" speeds we were used to with modern battery runtimes.

And honestly, lighter cars would be a little more safe for turn marshals and spectators. I remember being hit in the ankles and shins while marshalling a carpet oval! And seeing cars cartwheeling into the crowd that was sitting 10 feet away from the track. No one ever got seriously injured, but it could happen.

I used to love racing because there was no weight limit. I remember doing everything I could to get my cars and trucks as light as possible. Right before my local track closed, they started having weight and height requirements. I remember adding several ounces of weight and adjusting my shocks just to make the cut.

I think the 1S and 3.5T brushless would be a great idea.

ya know ive had this though and similar conversations with the "old guys" at the track. i agree that a smaller voltage and higher kv is a valid idea but you do get more efficiency out of a setup with lower kv/ higher voltage

i do believe in adding weight to tune the car though not to just add weight to make the car more drivable.

A higher turn motor is more efficient. There's no denying that. Still, a modern low turn brushless motor is still far and away more efficient than the old brushed motors.

I do add weight to my cars to help in the handling department but the weight is strategic.

The idea just came about as I said when we were thinking about American vs Japanese sports cars. American cars have more power but are heavier. Japanese sports cars were lower in power but lighter. Each design had merit. They each also had their advantages and disadvantages compared to the other camp. The idea was that modern rc has turned more into the American sports car. What would it be like to take a Japanese sports car like approach to rc cars by going really light but with lower power?

It's merely an idea, not a wish for any official class to be created around it. I honestly don't think any exotic materials would have to be used to accomplish it. At least nothing more exotic than anything else used today. Most cars can be made quite light without the electronics installed. It's mostly through the weight savings of the electronics and battery that I'm basing the idea around.

We had also talked about another setup that is similar in some ways. On ebay a company called Team Blue Groove sells SCT bodies that are made for 1/10 buggies. They are smaller than the SCT trucks that everyone drives. These are literally just SCT bodies you put on a 1/10 buggy, 2wd or 4wd. In some ways they remind me of the Pro Light series of the real short course race trucks. Those trucks are smaller, lighter, and less powerful. Yes they are slower too. We started talking about these and then evolved our conversation to our old real cars which then evolved into the light rc car idea. We think differently! I actually kind of like the idea of using one of those SCT 1/10 bodies on my RC10. I've heard the quality of their bodies isn't all that great though but it could still be fun.

It's like the real pavement modifieds we run in New England-you get the car as light as possible. Then you add weight where you want it on the chassis to get your desired "weights" on each wheel. Fortunately, I have never seen someone scale an RC car. Granted we run strictly ovals, but to be able to add here or there on the chassis can only benefit depending on track, conditions, etc.

Surprised no one has mentioned the shorty Losi lipo pack (and others now coming along) that some are running, plus lipos are lighter to begin with than the round nickel thingies (at least I didn’t notice if anyone did mention). Although the top Losi guys appear to be going back to full size packs.

I fought the heavy off road car thing for a long time, but gave up when I finally tried adding weight after my Son did and liked it. Takes some retuning but it just seems to work.

My theories, and they are just that, theories, because I agree it just doesn’t seem to jive with ol’ Isaac’s Laws and all of the full scale racing I’ve been involved in:

1) Cars don’t scale exactly, a 1/10 scale car is ~1/1000 the weight, and the tires are pretty big scale wise. The tires don’t seem to dig in and develop traction with a light car. There is a limit to how soft they can be to regain traction, etc. Yes, less mass should take less traction, I know, but I also work in the rubber biz and know tire traction is not linear with weight. (Rubber is a unique material, counter intuitive more often than not. Off subject a little but the non linear tire traction is also a big part of why anti-sway bars work)

2) Unlike full scale we don’t have the seat of the pants accelerometer to use to respond to the nimbleness of a light car. Just seems easier to push a heavier car, more stable in ruts and slides and such. In the same way a larger scale RC is generally easier to drive. Ever wonder why 1/8 is so popular and 1/12 not so much anymore? (Yes, I suspect a certain gender symbolism has something to do with it too, and other factors of course)

3) Unlike full scale we routinely jump 10 story buildings. The weight is really noticeable in truck, helps keep it stable in flight. (I haven’t tried short bus yet, but if and when I do will that thing ever be a lead sled, they look like parachutes out there sometimes)

I know first hand that one of the fastest trucks in all the land, multiple ROAR national champ in stock (with brushed) and super stock, every modified A main since including a 2nd, is also the heaviest truck I’ve ever seen. No matter how many times I look at it I’m still amazed how much lead that thing has in it. Yet it still looks as nimble as they get. Sure he’s a world level (literally, just made both As) driver, but he’s slower without the weight.

Sorry if I’ve rambled some.
Regards

I run 6 oz in my RC10T, way more consistent-

I added a half pound to my RC10 lengthwise down the chassis on either side of the battery and had it handling great. it broke pretty quickly when i wrecked it though. Clearly you need some weight since a car that is weightless would have zero traction.

Have any of you guys ever seen the 1/16th scale Traxxas trucks run around? There was a guy in a mini E-Revo chasing use around the track with our 1/10 scale buggies and he was having no problem whatsoever keeping up with us. it was a bit maddening actually. Our cars definitely weighed more! The mini E-Revo actually uses 2.2 tires but it has a shorter wheelbase than we run. For a small truck it is quite large, if that makes any sense, but still smaller than us by a fair amount. Again, no problems keeping up. They do run 2S lipo batteries but on smaller 380 motors at 3800 kv pushing less weight.

Yeah, they are also 4wd-