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Old Feb 16, 2013, 09:59 AM
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GetToDaChopper's Avatar
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it looks like it's tipping a bit forwards.......
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Old Feb 16, 2013, 11:11 AM
A man with too many toys
United States
Joined Feb 2001
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How well does the GPS hold altitude?


If I put it in a 2m hover will it hold that altitude fairly well?

Does GPS control both throttle and collective if I use a standard pitch curve or does it only control collective pitch and I have to use the governor more for throttle?

.
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Old Feb 16, 2013, 12:59 PM
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Lake Zurich, IL
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GPS without INS ( Inertial Navigation System) is not going to work much for most of RC flight.
http://en.wikipedia.org/wiki/GPS/INS

Altitude can be maintained within 1 meter using barometer sensor; GPS with INS is to hold position without much of drifting. Altitude hold can be done without GPS.

Collective does most of the work rather than throttle. However, for electric heli use of governor is not a must. This is from my experience flying GPS heli for about 19 months, not SK system.
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Old Feb 16, 2013, 04:17 PM
A man with too many toys
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So are you saying that Skookum forgot to add INS. For that price it had better have everything or I will definitely be looking elsewhere.


My low cost APM 2.5+ that I have on my Y6 and Quad has INS. I think Skookum has all the sensors necessary (3-axis accelerometers) so it will only take firmware to get INS up and running.


.
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Old Feb 16, 2013, 04:45 PM
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Quote:
Originally Posted by RC Man View Post
How well does the GPS hold altitude?


If I put it in a 2m hover will it hold that altitude fairly well?

Does GPS control both throttle and collective if I use a standard pitch curve or does it only control collective pitch and I have to use the governor more for throttle?

.
No, I did not say SK forgot to add INS which is the algorithm in flight controller using GPS. I was merely answering your question "How well GPS hold altitude?"
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Old Feb 16, 2013, 06:23 PM
A man with too many toys
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Ok then my new question is how well does the Skookum GPS hold altitude? Will it hold +/- 1 meter? I would think that would be the minimum acceptable for a 3D helicopter.


.
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Old Feb 16, 2013, 07:43 PM
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when you are flying 3D or stunt, you would constantly applying cylic/rudder while GPS position and altitude hold are meaningless. Only when you let go the control, the system would self level and maintain altitude. Holding holding position requires GPS/INS; holding altitude does not require GPS but barometer sensor; the biggest question is how quickly can the sensors react for split second stop and go plus the flight control algorithm perform.

I can't answer your question, I don't have one. I am sure others will comment.
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Old Feb 16, 2013, 09:15 PM
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Quote:
Originally Posted by RC Man View Post
Ok then my new question is how well does the Skookum GPS hold altitude? Will it hold +/- 1 meter? I would think that would be the minimum acceptable for a 3D helicopter.


.
You say that you think that 1m would be the minimum for a "3D helicopter" which makes me wonder what specifically are you wanting the GPS altitude hold to do in regards to 3D? 3D and altitude hold have nothing to do with each other in this case.

The rescue now function on the SK GPS will send the heli up to 8m when activated and hold it there if you get into trouble while doing 3D. You aren't anywhere close to the ground at that point. Its not going to lock it place where it sits in front of you while doing 3D if that is what you are asking.

If you are talking about simply locking the heli in place in hover wherever you want, then this is what the manual says regarding your controls when doing so:

"This will stop and hold the heli in both altitude and position. Pilots will still have normal yaw (rudder) control, but all other controls will not work normally. Instead, you can change the held position by slewing the heli using aileron, elevator and collective."

As Sidney stated, the barometer is what holds the altitude. There are plenty of videos out there of RC helis and quads using GPS and barometers from several vendors to hold them in place in hover. This isn't new or groundbreaking to do this, and the ones I have seen hold quite well. There is no moving up or down 3 feet while hovering, so I think your 1m wish is reasonable.
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Old Feb 20, 2013, 06:10 AM
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Quote:
Originally Posted by RC Man View Post
Ok then my new question is how well does the Skookum GPS hold altitude? Will it hold +/- 1 meter? I would think that would be the minimum acceptable for a 3D helicopter.


.
It hold beter than +/- 1m

SK GPS position hold (6 min 3 sec)


In this mode only rudder control.
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Old Feb 20, 2013, 10:30 AM
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Nice ! well done......
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Old Feb 20, 2013, 10:50 PM
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Quote:
I wouldn't call a magnitude 8 vibration 'not so much'. Those are almost catastrophic failure levels.
almost catastrophic failure levels !!! LOL not even but it all depends on what the cause is BUT still 8 vibration = catastrophic failure ??? how weak are the helis you build ??? lol
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Old Feb 20, 2013, 11:48 PM
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Got a question for you, GetToTheChopper,

How did you setup an SK720 to be a standalone vibration analyzer?
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Old Feb 21, 2013, 01:56 AM
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Just stick the SK720 on the heli, give it power, and it'll log all the vibration for you.
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Old Feb 21, 2013, 02:21 AM
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i did much more than just hooking it up (none of which is needed to use it as i do, i just wanted it to be smaller, lighter, and easier to hook up), so i cut off the connection rail and cut down the case to a 1 inch square then i took the S.Bus adaptor cable and cut it down so it was smaller and ca glued it to the CPU, i ran the S.Bus cable from the RX through a hole i drilled in the case to the skookum S.Bus adaptor that's now inside the unit but i took the power wires from there and ran them to the former power connection rail on the board connection so that whatever voltage my RX has the 720 does as well which is 6.0, then i took the skookum S.Bus adaptor signal wire and connected it to one of the sat port signal in on the inside of the unit because you need some kind of a signal to initialise the unit and then to trigger the 720 to start recording a log file, now it's smaller, lighter, and there is just one cable to connect to the RX, it still records everything it did before, it works awsome as a diagnostics tool that can log everthing from a flight for people who don't want to use a 720 oh and they already have the diagnostics software as well which is the skookum data viewer, i think skookum should make these and sell them as there is no development costs because they already have the hardware done so it's all off the shelf and they don't have to worry about how good they fly because they are just for logging and diagnostics, they would sell a ton of these things !

OH and one more thing, the micro SD card is now SUPER EASY to get to !!!
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Old Feb 21, 2013, 09:38 AM
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Quote:
Originally Posted by GetToDaChopper View Post
i did much more than just hooking it up (none of which is needed to use it as i do, i just wanted it to be smaller, lighter, and easier to hook up), so i cut off the connection rail and cut down the case to a 1 inch square then i took the

OH and one more thing, the micro SD card is now SUPER EASY to get to !!!
Wow,you are a real Skookum killer ;but, you know what's up, SK720 really doing well now.
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