GS023

Anyone tried any of the iphone lap timer aps?

Thanks

davidfarmer

I have Harry's Lap timer, and while it does a lot of cool things, the one time I used it along with a transponder, the times were not accurate at all. I'll be using it more, mounting it further up on the dash, to see if this helps, but then I won't be able to see it.

You can use an external GPS with it, but that sort of defeats the purpose of having an integrated device.

Anyway, if you want precision, it probably isn't for you. If you just want ballpark data, it is a great little app, with straight line speeds, corner speeds, G's, mapping etc.

95jersey

I use Harry's Lap timer as well, and it is very cool. It is an iPhone, so it will never be as accurate as an expensive GPS unit. The trick with using the iPhone as a lap timer is to securely mount it where it gets optimal reception. But again the key is to securely mount it so it doesn't move or vibrate. Needs to be rock solid.

GS023

Any recommendation for a mount?

Thanks

Richor

duck tape of course

95jersey

http://www.proclipusa.com/

I have had sucess with a belt clip on the visor, with the visor turned outwards so the phone has access through the windshield, but here is one made for the vette specifically and it states it is stronger than suction cup.

96CollectorSport

There is some good info on this thread over on the NASA forums, it starts out talking about transponders but then goes to lap timers from there.

http://www.nasaforums.com/viewtopic....&sd=a&start=10

95jersey

LapTimer heavily depends on GPS quality the iPhone delivers. This page discusses options and background information.

Device mounting is absolutely critical for accurate operation. When using LapTimer on a bike, mount it to your steering rod. This gives a perfect view to the sky. When using LapTimer in a car, positioning is trickier. As the car‘s body shields signals, move your iPhone as far to the windshield as possible. Testing this in my own car, I got an average accuracy of 40m when the iPhone was mounted near the dash board, and 20m when positioned directly behind the windshield.

LapTimer shows GPS quality as green / yellow / red. When the quality indicator drops to yellow frequently, or gets red, your mount position is not good enough and needs some more trials

longdaddy

an interesting option would be tomtom's iphone/ipod dock GPS reciever combined with an app like that (search for "TomTom car kit for iPhone")

still nowhere near the precision of pro/semi-pro data units, but probably a lot better compared to the pathetic GPS iphone has.

here are the specs for the GPS chip that tomtom uses (i think it's the same one "SiRF StarIII")

http://rightwaygps.com/pdf/mini-S3_specs.pdf

tomtom's "cradle" will run you about $120 but you get a charging ability, windshield mount and a GPS reciever in one package.

Corvee

Cantrell has a "stand-alone" application for I-phone. Based on your reception area, the lap timming is a bit inconsistent if you don't utilize an external GPS, but it is a "free application".

http://www.cantrellmotorsport.com/cm...mer/index.html