Clutch! (sorta)

Steve · #1 03-02-2006, 04:36 PM

I'm not sure if this does anything yet, but here's the general idea.

The drive gear hole is enlarged so it spins freely on the axle. A slot is cut in the gear so as to accept a pin that extrudes from the wheel. Once assembled, the drive gear will have some "play" before it is engaged by the wheel pin. In essence, the motor and drive gear start spinning before the wheels are forced to spin.

I was hoping this might give the car a little boost out of the hole, though it might just cause the tires to spin easier... testing is definitely in order.

Michael.mt2k · #2 03-02-2006, 08:07 PM

Interesting idea!

I'm looking forward to seeing how that works out.

frizzen · #3 03-03-2006, 12:02 AM

Might help, but I'm not sure that it'll let it slip enough to get RPM up enough for the horsepower to help it with the lack of torque. You might want to add some mass to the geartrain on the motor side of that, otherwise it might not be able to do anything more than *free spin, boom, bog, spin up normally*

Michael.mt2k · #4 03-03-2006, 08:47 AM

Like a flywheel or something!

#5 03-03-2006, 02:15 PM

If this is going on a higher power system, I think you're going to get a lot of wear on the plastic gear. It's definately a unique thought and I'd be interesting in what it does. I would have done it with a blue set first rather than wrecking the fastest gears.... I have a few extra blue, but all my red are being used. Let us know.

Steve · #6 03-03-2006, 05:44 PM

Quote:

Originally posted by frizzen
... otherwise it might not be able to do anything more than *free spin, boom, bog, spin up normally*

Yeah, I was thinking the *BOOM* might do a "little" something. Actually I was pretty bored and it was simple enough to try. Someone mentioned adding mass to the motor side somehow, and that sounds like another really good idea...it would make the *BOOM* have more of an impact.

Michael.mt2k · #7 03-03-2006, 08:06 PM

Maybe you could get a similar effect without the added mechanical concerns.

Well, it just transfers the concerns to electrical/electronic ones!

What I was thinking was maybe the use of a cap or something to give a slight boost at launch.

frizzen · #8 03-03-2006, 08:43 PM

But by using the fastest gears (least torque) it'll make the difference (if any) much more apparent.

Anyway, looks good. Keep us updated!

Steve · #9 03-04-2006, 08:20 AM

Quote:

Originally posted by Michael.mt2k
...What I was thinking was maybe the use of a cap or something to give a slight boost at launch.

I've been working on the capacitor NOS system for quite a while now, though I've never been successful. If only I was an electrical engineer...

Steve · #10 03-04-2006, 08:47 AM

Initial results are in!

Red Motor, Red Idler, orange (clutched) drive gear, Stock 4th Gen SE.

First tested with the pin forward in the slot so no play available.

3 foot trap, 5 run average: .8346 eta / best run .820

Second test with play available.

3 foot trap, 5 run average: .8166 eta / best run .808

BOOYAAH! IT WORKS! There is certainly a difference in accelleration. However, there is also more wheel spin off the start using the slot, so it's my bet that if traction issues were solved, there would be even better numbers. Exciting news from the engineering front!

...and then there is balance. I imagine this axle setup will have balance issues at higher speed. But that's for another day.

Steve · #11 03-04-2006, 10:48 AM

here's what it looks like in slow-mo, though not quite slow enough, you'll need to go frame by frame to really see it. The colored dot goes from red (no power), yellow (power to motor), green (power to wheels).

200k WMV Video

Steve · #12 03-04-2006, 10:51 AM

Here it is with a body and a little added CG for effect. If you really look close, you can actually see the car lurch and twist from the torque, I had no idea these little things could do that.

1MB WMV video

frizzen · #13 03-04-2006, 06:57 PM

That's a very nice set of hole-shots!!! Didn't expect nearly that much wheel spin out of it, how sticky of rubber are you running? So am I seeing silicone or foam tires in your future?

So is your 3' trap roughly scale for the 60' trap? Anyway, killing 0.020 /sec at the traps that close to the tree is amazing! Glad to hear it doesn't go *boom, bog* but *boom, spin* I wish the KITT Racer gears were still possible to find....

VERY nice to see what happens when you can basically wind it up a bit and side-step the clutch!

Steve · #14 03-05-2006, 10:27 AM

Right now, I'm using the Radiohack wide tires, with the shiny rubber sanded off, scuffs if you will. I wish I could find silicon tires that fit. I know they make them for slot cars, but I can't find a shop near me that carries them. I'd like to get my hands on them first before buying them just to see for scale and fit purposes. I don't think foam tires would help my cause, my track surface is just paper (foam board), so unless a lot of traction compound was used, I don't think they'd hook up.

As for the trap, it's 3 foot (1:1), so in 1/64 speak that's 192 feet. I tried a scale 60 foot trap, but my timer is not accurate enough to measure it. In any event, if my math is right, the car averages roughly 240MPH scale speed in that 3 foot span.

In regards to traction, I'm working on a pro-stock dragger with the batteries moved to the rear of the car (mid engine mount). I'm hoping to experiment with weight transfer, such that the weight of the car really sits on the rear tires during launch. I don't want to add weight to do it, just move whats already there around.