jmellipse

Motors in the wheel is something I have on my mind for a long time now.
Simple out runners that are used for indoor rc planes. You do get more weight in the suspension, but the possibilities are endless.

Everything will be in software and be dynamic.
Differential can be done in software based on the servo angle input.
Overdrive and under drive (what used to be a bigger or smaller pully) can be done while accelerating or braking.
Also brake harder front or back, esp etc.

4 small escs (or 4 in one) with small gauge wire. Imagine how much freedom you have in the car that only needs to house the esc(s), battery and steering servo.

EDWARD2003

iTrader: (8)

That's a good thought jmellipse.. Eliminate having a drive shaft all together, and just run two brushless motors in sync with each other providing direct power to the gear boxes. No need for spur gears and pinions. The motor shaft would act as the input shaft which the small gear will be mated to the differential ring gear. This would leave the middle of the chassis for electronic placement.

Just an idea : )

niznai

This has been done already by Hirobo years ago. I bought one of these cars NIB and sold it on immediately because I did not like the design. Theirs was not a top racer (the year is 1988) but in context perhaps good enough. To me it looked fragile. Apart from this, the design does not address the issue of torque steering and raises the CG considerably because of the motor position above the shaft.

http://www.tamiyaclub.com/showroom_model.asp?cid=112445

niznai

The motor does not have to be physically in the wheel. It can be on the chassis and use a short driveshaft to drive the wheel. Diff becomes redundant and you only need one ESC with multiplexed output signal to each motor kinda like the ESC used in Tamiya tanks with two motors.

ESC/transmitter settings can then take care of diff action and I would imagine a simple dial would be enough to switch from spool to diff to limited slip/torque biasing. Endless possibilities.

bucketboy

People shout "cheat" with ESC that give boost or motors with supidly high timing built in, although the electronic diff sounds doable, it would need to be connected to the steering, it would be way too easy to build in some sort of gyro to assist the driver.

Also, modern R/C electronics are very reliable it is the only reason I have had any DNF's in a very long time, having two (or four) motors and the speedcontollers for them could result in too many faiure to be race worthy.

Bb

inpuressa

iTrader: (10)

To me, Tamiya is the only company that constantly thinks outside the box and actually produces a product. It may or may not be a hit, but at least they act on it. The DB02 and the TA06 is a prime example. After all, they brought the TA01 and the TRF414 to the world.

BTW, who decided that you cannot have a slipper clutch on TC?

terry.sc

To be exact, Peter Winton when he wrote the first draft of rules for touring cars way back in 1996, rules which were then ratified by the BRCA members (a majority vote by drivers in the UK) for racing in the UK, then copied by IFMAR and all other racing organisations around the world. So if you want someone to blame, then that's all of us who race in the UK.

At the time slipper clutches were only available as an expensive upgrade for the YR4 and HPI RS4 costing half the price of the car kit, and nothing else. Banning slippers meant there was one less option part that could be sold to us on top of the price of the chassis, and they weren't really necessary even back then when we had much harder tyres and less sophisticated chassis designs. They are even more pointless in touring car racing today, but if they were allowed everyone would be buying them anyway.

terry.sc

You mean like we had all through the 90s, right up until the manufacturers decided the low level layshaft was the way to go. The early Yokomos up until the MR4TC had the spur on one end of the layshaft with a low drivetrain, but it means an upper deck high enough to pass over the top of the motor as the motor has to sit across the middle of the chassis unless you use really long pinions to reach across to the spur gear.

The low transmission with a low top deck chassis design lowers the CoG for better performance. Replacing the spur gear isn't that important, usually drivers will know what gear ratio to run at a specific track and if a spur gear is damaged it isn't that difficult to remove the layshaft in a modern chassis.

terry.sc

Motors are usually placed where they are after extensive testing by the manufacturers so they have already decided what they think is the best location, although as the layshaft mount is separate from the rear gearbox these days it's not difficult for anyone to move the motor forwards by making a new chassis and top deck and sourcing a pair of different length belts. In fact, drifters turn around the drivetrain to mount the motor forwards usually by just cutting a new chassis plate.

inpuressa

iTrader: (10)

ah, so that's what happened. I guess that shuts the door on the possibility of a center differential. But on-road touring defies several conventional vehicle tuning (like the use of a front spool), so a center diff might not do anything.

So I guess the general consensus is that the general designs of TC will not change for at least the next 10years. Why change something that works?

niznai

Because you designed something better and perhaps even cheaper?

I contemplated the possibility and usefulness of having a front slipper clutch instead of the spool (my car doesn't have ECS driveshafts as an option) and still am. I think it would be a good compromise between having a spool but no ECS and set right it would be exactly the same minus the understeer.

syndr0me

iTrader: (32)

Hudy's latest column has some good info in it about what went into the design of the T4, and why they made the decisions they did.

Of particular interest to me was the part about the car stopping in the corners. That's what I felt every second I drove the T3'12, and Martin explained it perfectly. What's odd is many other people told me they never felt anything of the sort. So maybe it's an issue that's exposed by certain driving styles? I dunno. That car always felt so weird mid-corner. Perhaps that's fixed on the T4 now.

terry.sc

Nothing in the rules bans a centre diff, it's just there isn't a performance advantage to using them. You could try a centre diff, they used to be used quite often in 4wd buggies in the 80s until we started to run more power through them.

With the low weight of r/c cars what happens is all the power ends up being sent to the end of the car with lower grip, so when accelerating the power goes to the front wheels which leads to wheelspin, and under braking it brakes the rear wheels, so locking them up.

R/C cars use exactly the same dynamics as full size cars, it's just that the dynamics don't actually scale. Touring cars in full size would be a 4wd rally chassis, with about 1000hp and the weight of a kart.

terry.sc

Associated already make one.
http://www.teamassociated.com/parts/details/31174/

Lessen

iTrader: (2)

I made one of these for my JRXSR. Just removed the balls and inserted a couple fabricated pieces of lexan to take up the gap. I hated it, but I am also used to running a front diff.