mark kibort

I found out how they work. they work on a basic bubble meter inside. so, if it is standing up, it thinks you are pulling 1 g in decel or accel, depending on which is up. so, it needs to be level or 0'ed out to find level. dive and rocker will toss off g acceleration rates, but lap times should not be effected.


mk

mark kibort

Ill have to check it out for my next race at Thunderhill and the toyo vs Hoosier tests.

mk

timmhaines

rubber band around ashtray and phone holds it in place, use a silcone case for phone. Dynolicious is pretty accurate, good enough to show improvements quick and easy.

ervtx

My observations on Larry's Lap Timer Pro after using it at 3 different tracks...

GPS reception: average of 32 ft. accuracy using the internal GPS receiver; 16 ft. accuracy using the Bad Elf external GPS receiver for the iPhone. I've seen other reports that the Tom Tom adapter works better than the Bad Elf, but it would have to be a lot better in order to map useful lap to lap comparisons.

Accelerometer: it does use the iPhone built in accelerometer to augment the GPS data. Lat/long g force readings are therefore more consistent/accurate than track position and speed.

Automatic overlay of log data onto video: The app controls the internal camera application for video recording, and is able to overlay track map/position, lap timer, g-force, and speed data onto the recorded video as a separate step after the fact. The iPhone cannot handle the bandwidth of continuous and simultaneous video buffering/writing and data logging, so the app will record video only for every other lap. This means that you may not have video of the lap that you want to evaluate together with the log data (e.g. "best" or "reference" laps). Here's an example of the video overlay:



You do not need to have the iPhone mounted for video recording, but you do have to have it mounted somewhere on the dash or windscreen for decent GPS reception. I have an extension cord for the bad Elf GPS receiver, so if I'm not interested in any of the real time displays, I can put the iPhone in the glove box and simply route the cord to a location on the dash or windscreen.

Log files: The unit of reference is a single lap. Every file that the app produces is for a single lap. If you want to compare two laps, you have to select each lap and export the files for those two laps. I believe that the cvs output option is compatible with TrackVision, but have not confirmed this. Additional outputs that can be exported include .kml (Google Earth). The overlay looks cool, but due to GPS accuracy issues, it is fairly usesless (see pic below, and my "apparent" off at 78mph on my best lap of the day). The kml output only includes GPS accuracy readings, GPS fixes, Lateral Acceleration, and straight/corner speeds, but the cvs logs have much more detail. Output options include email, and dropbox. I use dropbox and it works perfectly.



The app also has some basic analysis views right inside the app. I've included some screen shots below.








More screenshots here... https://rennlist.com/forums/members/...timer-pro.html

Tracks: extensive database of tracks, including separate POI sets for tracks that are run both CW and CCW. The POI sets for the tracks that I run on are split into either 2 or 3 sectors. (In the video above, you can hear a beep as I cross each of the POI's). The start/finish line is always the 1st POI, and this facilitates accurate overlay onto any video recordings, as well as the most useful feature of the app: automatic start of logging and video recording. In the most basic mode, just launch the app on the grid, and it does everything else automatically.

Online publishing... the app has the ability to publish log data to an online server in near-real-time. When this option is "on", anyone else with the app has the ability to see your track position and lap times on their iPhone or iPad. Not that useful while in the car (unless knowing a competitor's position is more important to you than the other readouts on your own laps). However, it's potentially useful for watching 2 or more cars using the app from track side. No gap information in the display, but it does keep the last 6 lap times overlayed on the display, so if you're monitoring 3 cars, you see each of their last 2 lap times.

I've stopped using my previous data logger (Performance Box), and no longer mount a dedicated video cam. It's an excellent alternative for the casual track day user at a much lower cost and hassle factor. But it's not going to be useful for those who need a more accurate and robust solution for race conditions. I think that the best part of the app is yet to be understood... the potential network effect from online publishing. I can imagine all kinds of uses. For example, imagine a typical PCA club DE, where students in the advanced run group usually have on-track observations that they want to compare with others' in the classroom sessions for the benefit of one or more drivers. Now imagine these discussions augmented by the observations of an advanced instructor who had been watching the results in this app from track side, or even using the drivers' dropboxed files to illustrate coaching points on Trackvision. All it would take is for enough drivers to individually purchase the app in order to participate (network effect), plus one additional purchase of the app by the PCA club for instructor use. I know that something similar has been tried before using Trackmate and video, but it was logistically not practical in the context of a DE schedule. The ease of publishing data from this app is a huge step forward IMO.