RE: GPS guidance

RE: GPS guidance
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RE: GPS guidance - 5/6/2006 2:13:45 AM

lvspark

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From: WALLA WALLA, WA,
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It might, but you won't see me standing anywhere near-by!

(in reply to Widgeo)

Post #: 26

RE: GPS guidance - 5/7/2006 8:25:00 PM

vortex00

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From: Edgewood, KY, USA
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Can I use my Garmin etrex with the new RCAP2?

Jack

(in reply to Widgeo)

Post #: 27

RE: GPS guidance - 5/7/2006 8:40:16 PM

kd7ost

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From: Nampa, ID,
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quote:

ORIGINAL: vortex00

Can I use my Garmin etrex with the new RCAP2?

Jack

Yes,

Go into the "Setup" menu then "Interface" menu option. If not already done, select NMEA out in the I/O format. Garmin units come defaulted to Garmin I/O. It's an easy swap. Then just use an eTrex serial to DB9 cable to connect up to your RCAP unit. You can also custom make smaller lighter cables. I recommend powering the eTrex from an auxilliary regulated power source. This keeps it operating in the air much better. The Garmin units in my assessment and experience can shut themselves off under vibration conditions. This might be due to battery compartment connections. I never have experienced a shut down with my geko while powering it externally. Here's a thread on a hack that may or may not do you any good. It's a lot cheaper than a factory OEM cable and is very secure if done properly. The little connector Garmin uses on the back of the eTrex has to be handled pretty carefully to stow in flight. You don't want that little thing popping off or your guidance is gone in a heartbeat. http://www.rcapa.net/forums/viewtopic.php?t=503

Dan

(in reply to vortex00)

Post #: 28

RE: GPS guidance - 5/7/2006 9:42:05 PM

vortex00

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From: Edgewood, KY, USA
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Dan,
Thanks for the good info and start into the UAV world. Excellent link.

Jack

(in reply to kd7ost)

Post #: 29

RE: GPS guidance - 5/8/2006 6:42:01 PM

wsmalley

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From: Monterey, TN, USA
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What's the least expensive GPS today for flying waypoints? I have an old Garmin 12 which is too heavy. I have an original PDC 10 and an overlay from BlackBox in the UK. Was thinking of getting the eTrex-the first yellow one. It appears the WAAS data is not sufficient for altitude purposes at our scale. I read somewhere the 'automatic landing systems' on some full scale A/C uses 2 units with DGPS. I thought WAAS was supposed to be extremely accurate? Maybe the guys in black suits are varying the data.

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Post #: 30

RE: GPS guidance - 5/8/2006 8:35:55 PM

kd7ost

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A lot of us are using the Garmin geko 201. It's pretty small and pretty adaptable to our use. I always try to tell people it's best, especially with wet fuel planes, to use auxilliary or external regulated power to the GPS. There have been reported and I have seen the GPS shut off in flight if you only use internal batteries. The battery holder in the back case of the unit just has two tabs holding power to teh circuit board so I suspect this is the problem. There is also a tiny battery inside that I've had vibrate loose and cause me to have the GPS shut down. There's a link to a modification and cabling that makes the unit more UAV freindly that I can post later. It's on the RCAPA forum site but they have me blocked from my work e-mail address so I can't recover the link for you.

Dan

(in reply to wsmalley)

Post #: 31

RE: GPS guidance - 5/9/2006 1:40:33 AM

kd7ost

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Here's the link.

http://www.rcapa.net/forums/viewtopic.php?t=503

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Post #: 32

RE: GPS guidance - 5/10/2006 11:03:45 PM

wsmalley

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Thanks for the info and the link. The hack looks pretty simple. Does the 'geko' have features that the basic eTrex doesn't have? I guess, that is, features beneficial to UAV use. Bill S.

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Post #: 33

RE: GPS guidance - 5/11/2006 3:55:36 AM

kd7ost

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They have pretty much the same features and software. Newer units have WAAS enabling which gets it a little more accurate. Either one will do you. The geko is a little smaller than the eTrex. I prefer my eTrex for back country use over the geko. But the geko over the eTrex in the plane just for size. Also, depending on how you mount it, the eTrex has buttons on the side and can be hard to access. The geko has them on the front panel. The geko buttons are easy to get to if the mount wraps around the case. It's really just DC. (Designers Choice)

Dan

(in reply to wsmalley)

Post #: 34

RE: GPS guidance - 5/11/2006 4:01:02 PM

wsmalley

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Good info! Question that comes to mind, though, is plotting waypoints in advance of a flight. That is, how? It seems the points have to be greater between them than the time it takes for the GPS to refresh. Then, does one normally walk, or drive, the anticipated route to set the wp's, or can you plot them off a map accurately enough? And, finally, can the GPS become confused as to which wp it's trying to acquire-seem to remember reading that somewhere long ago? Bill

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Post #: 35

RE: GPS guidance - 5/11/2006 10:22:58 PM

typicalaimster

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quote:

ORIGINAL: wsmalley
Then, does one normally walk, or drive, the anticipated route to set the wp's, or can you plot them off a map accurately enough? And, finally, can the GPS become confused as to which wp it's trying to acquire-seem to remember reading that somewhere long ago?

Bill,
Usually when I setup my routes I do it in TopoFusion and Expert GPS. These are programs that allow me to edit waypoints and routes. After I'm done editing my route I upload it to my GPS. If you have 'urban' satellite image coverage you can get some pretty accurate routes built. I've attached 3 jpg's to give you an idea of some routes I might fly....

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(in reply to wsmalley)

Post #: 36

RE: GPS guidance - 5/11/2006 10:38:33 PM

wsmalley

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Cool! I presume these are commercial software programs-expensive? Can your 'finish' point be at, or slightly past, your start point. My question being, basically, can you program your plane to literally fly down the runway? Sort of an automatic landing system.

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Post #: 37

RE: GPS guidance - 5/12/2006 1:35:15 AM

typicalaimster

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quote:

ORIGINAL: wsmalley
Cool! I presume these are commercial software programs-expensive? Can your 'finish' point be at, or slightly past, your start point. My question being, basically, can you program your plane to literally fly down the runway? Sort of an automatic landing system.

I think they cost like $30-$40 each. It's some software that I've been accustom to. There is other GPS software out there, it's just a matter of what you want to do with it.

As far as autoland this is something that has not been focused on by modelers just yet. There are some complications with it. I've been tempted to give it a try, just haven't had the time yet. Garmin's GPS's have something called Smart Route in them. This sometimes messes up your route. This is also why I put Start and Waypoint 1 very close together. When you start a route it automatically skips past 'start' and starts navigating to WPT1. If you put your Ending waypoints to close to the start it will skip over everything else and go right to the end.

If I was going to land with just a RCAP and a FMA CoPilot I'd have to set my route to overshoot the landing zone. In reality I'd still be landing at WPT10.. The Overshoot is so the RCAP doesn't hit the last waypoint and start circling. I'd still have to manage the throttle myself. The FMA CoPilot would then keep everything level. Then the RCAP would just stear the route. I'd still have to flare at the very end. If you look at the attached WPT6 to the end would be me attempting to keep the RCAP on a straight line.

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(in reply to wsmalley)

Post #: 38

RE: GPS guidance - 5/12/2006 3:40:15 AM

kd7ost

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Here's a thread thats worth reading at this time. It explains how steering devices control the rudder and farther on, how "smart route finding" gets in the way of what we're doing and how to get around it.

http://www.rcgroups.com/forums/showthread.php?t=475531

Dan

(in reply to typicalaimster)

Post #: 39