Brushless EDF Tamiya F103GT

[What's_nitro?]

I will make a bench test video in the near future. A road test video will take a bit longer since I'm still trying to work out the brakes.

I need to do three (3) things to finish this project:

1: Cut/bend the battery trays.

2: Solder-up a parallel plug for the batteries.

2.0001: Figure out the brakes...
2.9999: ...etc.

3: Done!

[Mallanaga]

done! is not a thing...

you have two (2) things you need to do to complete this project... get 'er done!!

[suicideneil]

Are you still goinf with the magnetic brake drum idea was it, or something different- I think some kind of disc brake mounted on the rear shaft would be good provided you could fab a hub/mount for the disc, then you just have to build somewhere for the pads to mount and then link them to a brake servo.... sounds so much easier when you type it, but building it is somewhat harder me thinks..... good luck!!!

[What's_nitro?]

I abandoned the magnetic brake because I could'nt find magnets with the correct radius, and because it locked out the differential which cut my turning radius a bit. It made the tires slide instead of roll and the foam wouldn't last long like that.

The only problem with a disc brake, as well as any other brake, is that it needs to be able to stop both sides of the differential or it wont do much at all. Usually this means replacing the differential gear with a brake disc with holes cut out for the diff balls. I thought about this method but I don't have the tools to be precise enough in making the custom disc, and I don't think any stock brake disc out there has the holes in the correct places let alone the right size hole in the center to fit the bearing.

I think I will try to modify the stock differential gear with some metal rings on the side for a disc brake setup. Some standoffs to hold the calipers, a servo, and voilla! Done! You're right- it does sound easier when you're typing it!

[lincpimp]

Use a pinion gear meshed with the diff gear like stock and attach the disk brake to that, at least it will brake like a stock electric motor vehicle would.

[suicideneil]

Ooh, good idea. If the stock motor mount was there still you could rig up a mechanism in the motor's place.... nice thinking that man.

[lincpimp]

Thanks neil, love that blue blob killing off the red blob, he sure is handy with a pistol!

I only say that cause I have experience with a f103gt. Never had any luck getting mine to track straight, so I sold it. Possibly mount a cut down section of a 2wd nitro trans so that the disk brake sits where the motor usually does and the shaft extends out to allow a pinion gear to be fitted. If the section was small enough a sub sized servo could be mounted on the other bulkhead and it would all be contained inside of the motor pod. It would add some unsprung weight though.

[suicideneil]

I dont think a few extra grams would make that much difference really, especially given the size of the motor/fan. **does the bonkers dance again**

[What's_nitro?]

I do have a disc brake setup from a N*tro Rustler that I could try to make work. I'd just have to fab some brackets and figure out a way to fit a pinion on, like lincpimp said. It would be sweet if everything could be made to fit in the motor pod.

[lincpimp]

I wish I still had my f103, I could make you a disk brake that would fit the bill just fine. The only problem i can see is that the shaft that the brake and pinion are on would have to be supported with 2 ball bearings. You could use the ctr bulkheads from a 1/8 buggy to hold the bearings and turn one inside out to but the brake assy between the bulks. The you just need a shaft that has the correct interface for the disk and machined down to 1/8" for the pinion. Or you could make the required bulks and shaft from scratch and use whatever brake disk that would fit in the space. Would be no bigger than 35mm, same size as a 540 motor.

[What's_nitro?]

Thanks for the help. I can't work on it right now since I'm in Arizona visiting family. When I get home on the 9th I'll take the topshaft out of the Rustler tranny and see how it fits.

What about reverse thrust as brakes? It seems that would be so easy to set up that it would be worth trying.

[What's_nitro?]

B15, the thought had occurred. I could do it, but it would require much more fabrication. Physically turning the fan around would be impractical, and reversing the fan would not work well since the thrust produced while running in the reverse direction would be minimal. The only other way would be to construct ducting around the sides to face forward, and then a means to convert from normal thrust and re-route the air through these side ducts. Extra servos/radio channels would be required. It wouldn't be as easy to drive with either, if you think about it, since brakes can usually stop a vehicle much more quickly than the vehicle can accelerate. With reverse-thrust brakes it would be a 1:1 ratio between acceleration and braking, therefore you need as much room to stop as you did to get going at that speed. I can see this method working perfectly for a drag car since they usually have plenty of room to stop.

Originally Posted by What's_nitro?

since brakes can usually stop a vehicle much more quickly than the vehicle can accelerate. With reverse-thrust brakes it would be a 1:1 ratio between acceleration and braking, therefore you need as much room to stop as you did to get going at that speed. I can see this method working perfectly for a drag car since they usually have plenty of room to stop.

I think youre going to have this problem anyway; if that fan can produce 5lbs of thrust, its going to be accelerating at well over 1g. The rear wheels wont be able to decelerate it anywhere near that hard.

[What's_nitro?]

If need be I'll put rubber slicks on the rear axle, instead of foams, to get some extra stopping power. If it turns out that this thing can't stop well enough then I might consider an air brake as well. Like the big flaps that open up on a 747 when it lands.