Tonto (D 515)
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Jan 30, 2005, 12:30 PM
Post #1 of 30
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161 MPH...
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Maximum ground speed on Foretrex 101 29 January 2005.
True, I was exiting in 40 kt uppers and heading downwind, but I still worked at it - and seeing the ground move by below at that speed is something worth remembering for a while.
Also did a tracking dive with 2 former AFF students of mine wearing FS suits and flew with them before climbing away.
Time? Umm. Looked at my Neptune for the 1st time after opening.. (Pro-Dytter and 2000+ dives at the same DZ precludes much staring at the clock) and the screen was blank but for a thin line. Flat battery.
I won't get full distance or time off the GPS either, as I turn it on just before exit and it takes 15 - 20 secs to get a lock. Doing it this way prevents me from recording the plane speed as my Maximum. (although I think a Porter would need to work quite hard on jump run to get 161 mpm..)
I won't get full distance or time off the GPS either, as I turn it on just before exit and it takes 15 - 20 secs to get a lock. Doing it this way prevents me from recording the plane speed as my Maximum. (although I think a Porter would need to work quite hard on jump run to get 161 mpm..)
I'll try download the dive tonight.
t
I just turn off logging until people start to leave the plane and then turn on logging. The GPS is on the whole time in the plane. This allows for better GPS accuracy due to the satelites having been accquired for a while.
I always go to the log for speeds because I enable logging just before exit. The forward speed drops quite a bit when you exit the plane. Since the GPS also logs altitude, the point when ground speed decreased and a descent has started is the exit point.
Even if the plane does some turns and descends slowly in between exits it is fairly easy to figure out the exit point from the log.
Which GPS are you using? Can it "see" the satellites from inside the plane, or does it just reacquire more quickly after exit due to having been on previously?
Tonto (D 515)
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Jan 31, 2005, 11:34 AM
Post #11 of 30
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Other than using AAA batteries the difference between the 101 and the 201 is that the data is not downloadable.
I upgraded my ForeTrex 201 to software version 2.40 and it is not connecting to my computer. I replaced serial cables and tried it on 3 different computers before sending it back to Garmin to be tested/replaced.
Kris.
Tonto (D 515)
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Feb 14, 2005, 3:33 AM
Post #14 of 30
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I thought the only difference was the power source. Taya and I chose batteries over the rechargeble version due to our frequent trips to places that preclude a recharge every 14 hours.. A pocket full of tripple A's weighs very little..
It has the plug and the PC connectivity cable, and I've managed to upload waypoints, routes and tracks from our Garmin E-Trex Venture and Legend.
I'm not sure what software version I'm running though.
I looked at the website (I do not own one) but i would think that it could download to a computer. Only thing I could see different is the size and battery. The 201 also looks different by saying it is like the 101 ... "yet is chocked full of GPS navigation features like the geko 201".
Quote:
The Foretrex 101 has all the features and functionality of the Foretrex 201, including PC interface capabilities for downloading waypoints, tracks and routes, but operates on two AAA batteries.
Again I do not own one so do not quote me but thought the stuff on the website was interesting. Also this looks like a fun device so I am interested to hear what it can and can not do.
(This post was edited by op5e on Feb 14, 2005, 4:35 AM)
In fact, the Max Speed foretrex show is not the horizontal speed, but the real 3D speed. You have to use some analysis software to get the horizontal speed.
In reply to:
So that's about 2,5 miles per minute...way cool!
What was your total distance (and time) on that flight?
Are you sure about that because I could not find anywhere that it mentions altitude on the foretrex. So if this is the case the only way I could see them getting speed is GPS. Asuming GPS is the only way they get the speed, it is still a good indicator of how fast you went, but yes there may be some variables (ie if you zigzag, 15m accuracy).
Anywhere near 161 is fast, wd tonto.
Tonto (D 515)
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Feb 14, 2005, 5:32 AM
Post #18 of 30
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leoholanda is right about the 3D speed, I think. When I turn the unit on, and it's aquiring, it 1st says 2D plus the accuracy, then later 3D plus the accuracy. That may drop the true speed quite dramatically.
I emptied the memory completely yesterday and wore it on one (pretty crappy as far as the numbers go) flight. I'll try and download that one - but not tonight... as it's Valentines day!
Yes, I'm sure... Foretrex does not have barometric altitude info, but it does have an altitude info by GPS. When I get home, I will take some pictures of its screen and I will write a step by step how to see the altitude info. When I jump, I use it as an digital display altimeter (like neputne). But, the altitude info is not above ground level. You can not zero it when on the ground. The altitude is above sea level.
Don't you have a serial interface to connect to your PC?
In reply to:
Are you sure about that because I could not find anywhere that it mentions altitude on the foretrex. So if this is the case the only way I could see them getting speed is GPS. Asuming GPS is the only way they get the speed, it is still a good indicator of how fast you went, but yes there may be some variables (ie if you zigzag, 15m accuracy).
Anywhere near 161 is fast, wd tonto.
(This post was edited by leoholanda on Feb 14, 2005, 5:41 AM)
LouDiamond (D 25931)
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Feb 14, 2005, 5:41 AM
Post #20 of 30
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A GPS receiver must be locked on to the signal of at least three satellites to calculate a 2D position (latitude and longitude) and track movement. With four or more satellites in view, the receiver can determine the user's 3D position (latitude, longitude and altitude). Once the user's position has been determined, the GPS unit can calculate other information, such as speed, bearing, track, trip distance, distance to destination, sunrise and sunset time and more.
leoholanda is right about the 3D speed, I think. When I turn the unit on, and it's aquiring, it 1st says 2D plus the accuracy, then later 3D plus the accuracy. That may drop the true speed quite dramatically.
Yes. Let's suppose you are moving at 126 mph of forward speed. If you are falling at 100 mph, the GPS will show 161 mph of total 3D speed. Since the square root of 126x126+100x100 is about 160.9...
I'm using CompeGPS Air to analyze all the flight data. It is just excellent! It also make 3D animation of the flight.
Ahh. That's sounding a lot more "real" now. Someone calculated the 161 MPH less the 40kt uppers as 114 MPH. Now with the 3D component added - the speed comes down closer to the 90 MPH that Birdman Inc believes the suit is capable of.
The economical Foretrex™ 101 is the wrist-mount GPS that frees up your hands so you can focus on your outdoor activities. This product joins the Foretrex 201 in Garmin’s growing line of wearable, wrist navigation devices. The Foretrex 101 has all the features and functionality of the Foretrex 201, including PC interface capabilities for downloading waypoints, tracks and routes, but operates on two AAA batteries.
Funny, for some reason I thought Excluding.....and I have not had a drink this year
It all depends in the fight angle you can do. I the example I draw, the angle was of about 38.5 degrees (assuming an horizontal line as zero), since tg(38) is aprox 100/126. In a real flight, the flight angle can vary a lot.
The attached picture of the jump profile was get using foretrex 201 and GPSTrackMaker software. I opened the parachute at 4000ft. At the first 3000ft the flight angle was about 56 degrees... but, as the flight goes on, the flight angle becomes better to 36 deg (at the last 2000ft) before parachute opens.
In reply to:
Ahh. That's sounding a lot more "real" now. Someone calculated the 161 MPH less the 40kt uppers as 114 MPH. Now with the 3D component added - the speed comes down closer to the 90 MPH that Birdman Inc believes the suit is capable of.
FasterGenes.JPG
Umm. Looked at my Neptune for the 1st time after opening.. (Pro-Dytter and 2000+ dives at the same DZ precludes much staring at the clock) 
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