Acceleration testing

[Colin]

Anyone got any good ways they time their cars when doing acceleration testing? I've used the downloaded data and our one lap beacon, it's accurate but is very time consuming as you need to look at the wheel speed signal very carefully to work out when the car starts to roll. I was thinking of hooking up a couple of those light beam sensors they use in shop doorways to a stopwatch, any ideas.

[Colin]

Anyone got any good ways they time their cars when doing acceleration testing? I've used the downloaded data and our one lap beacon, it's accurate but is very time consuming as you need to look at the wheel speed signal very carefully to work out when the car starts to roll. I was thinking of hooking up a couple of those light beam sensors they use in shop doorways to a stopwatch, any ideas.

[Chris Boyden]

try two lap beacons.

One at the beginning and the other at the end.

[Mad Ruska]

We build a ligth barrier. We bougth the parts by an electronic shop in the net, cost us about 60 Euro, and put it together. The bad thing, you need up to 100 m cable, but it works perfect, best and cheapest way to make it.

Frank

Stralsund FASE 1999-2003

[The guru of guru's]

why not get a third beacon and hook it up so you eliminate the 100m cable?

[Colin]

I had a look at jaycar electronics, you and can get a IR reciever/transmitter kit for $12 it has a range of 3m so it would be suitable for the the sae car but would still require the 100m cable, as for the suggestion of using a second lap beacon from boyden i had thought of that it's just that i'm finding it hard to justify giving MOTEC another $500 for it.

[Chris Boyden]

Ouch...$500. Motec is sure proud of their stuff.

We're using a MYCHRON3 Gold from AIM Sports. Their beacon is like 40 bucks.

You might be able to "hack" their transmitter.
if it is an IR transmitter, then buy an OPT101(infrared light to voltage converter) chip from Texas Instruments. It's like 5 bucks U.S.
then look at the waveform on an O scope. If you guys are good with microcontrollers, you should be able to take a PIC processor ($2) and recreate the waveform.

I know MOTEC is the cadillac, but man, it's priced more like a rolls-royce.

[George]

You can use anything as a lap trigger.

An idea i have heard of is using a g sensor and then like a stick on the gound - you get a vertical g spike when you go over it, using that as a lap trigger.

Just a thought - i haven't actually tried it.

[Colin]

thanks boyden i might give that a try the only thing is i think motec has a pretty serious encoding system so that lot's of car's can use their becons during a race and only get triggered by their particular beacon. as for putting a "stick" on the ground, that sort of thing can work well but it's like looking at the ground speed you have to look carefully though the data and i don't want to waste track testing time between each run.

[Chris Boyden]

Colin,

you might want to look at a simple Mychron lap timer. They're pretty inexpensive. Basically,
it's just an LCD display that shows your fastest lap, rpm, current lap, and has a small memory for storage.

Anyway, good luck.

Chris