After my experiments with the first fan car, I was really impressed with it’s speed on good surfaces (laminate, thin carpet), but it was entirely dependent on a smooth surface due to it’s limited (front) or no (rear) suspension.
For the second version, I thought I may as well start with an already competent RC chassis. For this I chose the WLToys 284161 – this is very similar to the K969, except it has stronger drivetrain (metal diff pinions), and uses longer spindles for the wheels to support the larger wheels. Like the K969, this has double wishbone suspension all round, and has a solid metal chassis base.
The modifications I had to make to this chassis in order to support the propellers were really quite minimal. I removed the driveshafts and prop shaft, both diffs, the motor. I made some minor modifications to one of the diff housings to make space for the controller. Then I modified a WLToys rear bumper to allow me to glue the existing prop nacelles from v1 onto the back of it.
Initially I was using all four of the 284161’s wheels – which are large off road wheels, but after a while I decided (almost entirely for aesthetic reasons) to change to an aggressive stagger, evoking 60’s F1 cars. I did this by putting shorter spindles in the front uprights, and using K969 wheels. This looked quite cool, but caused a fair amount of rake, which was reducing the ground clearance ahead of the front axle. In order to remedy this I have entirely removed the rear axle’s shocks. This has the benefit of also increasing oversteer.
After adding the staggered wheels, I also fixed the receiver/ESC directly to the chassis’ baseplate. My reason for doing this was to reduce the amount of the fans that are obscured – with the receiver sitting on top of the chassis brace, it was obstructing perhaps 20% of the frontal area of the two props.
Electronically, I didn’t really make many changes. I just took the two motors in parallel from the previous attempt, and soldered them to the plug for the WLToys motor, so they plug straight in. I don’t think these motors are technically compatible with this ESC, but I don’t know. The old motor and the new motors are both DC, but I’m not sure what kind of ESC you would typically use for a coreless motor. It works fine, however at full throttle the ESC seems to have issues, and will cut out. I have reasoned that the coreless motors have lower resistance and are pulling more amps? I don’t know though, my understanding of this side of it is quite lacking – I typically just plug stuff in and see if it works.
I have been considering whether/how to make a body for this. I think it would be interesting to make one from rolled out drinks cans.
This fan car handles well too. It slides less than v1, as you may expect with the massively increased contact area. The increased rolling resistance and weight does create a marked reduction in performance, but it’s still quite fast. It should be more forgiving of different surfaces with it’s suspension though.