Dragster shut down area - Printable Version

Dragster shut down area - Printable Version

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Dragster shut down area - Pineman - 4th-Nov-23

Hi, building a test track to try out my 1/24 scale dragsters, how do I go about calculating a shut down area for the car to stop ?

My space is limited, about 16 feet, was thinking of cutting the power off about 11 feet, anyone have any suggestions on how to go about this ?

Mike

RE: Dragster shut down area - woodcote - 4th-Nov-23

Ultimately, it’s going to be trial and error. As your strip is relatively short, the cars won’t have quite the same momentum through the finish line as with a longer strip - and they should stop sooner. Five feet of shutdown after 11 feet of powered running seems a good place to start experimenting.

For my HO strip, I cross-wired the rails after a short dead section to create a dynamic braking circuit in the shutdown. I don’t know if that would risk damage with the sort of motors you’ll be using? You certainly want to use some heavy gauge wire under the track and maybe introduce some resistors or diodes into the circuit to reduce the braking effect. A 1/24 drag strip owner would give better advice. The amount of braking effect will vary depending on the motor being used, so that’s another factor to throw in to the trial-and-error process.

An HO shutdown benefits from friction of the cars’ traction magnets - I’m not sure if there’s a safe way to add an element of friction to a 1/24 car. However, you could use gravity to help slow the cars, by adding an upward slope to the shutdown. It won’t have too much effect, but might shave a couple of inches off the required shutdown length.

You will absolutely, definitely need a well-padded catch box at the end, just in case things go wrong Ambulance

RE: Dragster shut down area - Pineman - 5th-Nov-23

Hey Andy,

Yes, ultimately will be a trial and error, I wish I had more space. That is a good idea with elevating the end of the track, will try that.

On your Ho track, regarding " I cross-wired the rails after a short dead section ,"can you explain specifically what you did ?

RE: Dragster shut down area - woodcote - 5th-Nov-23

There’s an image and explanation in this post: https://slotracer.online/community/showthread.php?tid=1253&pid=7413#pid7413

RE: Dragster shut down area - Kevan - 5th-Nov-23

Would a low reverse polarity voltage work better than a dead short?

RE: Dragster shut down area - Pineman - 7th-Nov-23

(5th-Nov-23, 07:11 AM)woodcote Wrote: There’s an image and explanation in this post: https://slotracer.online/community/showthread.php?tid=1253&pid=7413#pid7413

Hi Andy,

Not quite following what you doing, could you just explain in a brief sentence?

Also, for example, if the track is 20 feet, why not just place a tape where you have no connection after like 15 feet ?

RE: Dragster shut down area - KensRedZed - 7th-Nov-23

Tape will prevent dynamic braking, and allow the car to coast way too far.

Tape will peel off. Andy's solution is permanent.

RE: Dragster shut down area - woodcote - 7th-Nov-23

(7th-Nov-23, 07:31 PM)Pineman Wrote: Not quite following what you doing, could you just explain in a brief sentence?

I'll try...

The blue wires in the image are soldered to underside of the rails in the shutdown section.

The longer answer being...

After my powered section I have a 3" section that is unpowered and isolated from both the proceeding powered section and following unpowered section. That next section is unpowered, but the left hand rail of each lane is connected by wire to the right hand rail of the same lane. As the car freewheels, the motor creates current which is then short-circuited by the cross-wire. This applies a reverse force to stop the motor (and hence driven wheels) turning - also the principle of dynamic braking in any 3-wire controllers hook-up. Without the dynamic braking, the car would coast a long way, requiring a lengthy shutdown.

Hope one or both helps!

RE: Dragster shut down area - Pineman - 9th-Nov-23

Hi Andy,

Okay, thanks for the info.

RE: Dragster shut down area - Pineman - 28th-Dec-23

[attachment=33177]

[attachment=33177 Wrote:Pineman pid='35151' dateline='1699500559']Hi Andy,

Okay, thanks for the info.

okay, will this set up do the trick ?

of course will use thicker gauge wires and add in something for the missing rails.