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Old Jul 15, 2014, 11:20 AM
Registered User
United States, LA, Shreveport
Joined Jul 2013
144 Posts
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Originally Posted by Witterings View Post
Maidened mine this morning :-)
Lots of discussing props at the moment, if you're using 13" props what difference will the pitch make, I've been trying to find some 13 x 4's but there only seem to be 13 x 5.5 or 13 x 6.5's available in the UK at the moment.
I can only speak from experience since im not well versed on the science. But lets say all things are equal: going from 4 inches of pitch speed to 5.5 inches of pitch speed will increase your overall max speed of the multirotor. It will also increase your amperage draw. Lets say you like the flight time from a 13x5.5 prop but are overheating your esc's a little bit; you can drop down to a 13x4 or 13x3.8 and keep the hover flight time of the 13" prop, but loose high end speed and gain pulling out torque. In general if your going to buy a prop with more pitch just make sure the esc's/motors can take the extra load from the increased pitch. Best way to keep all that in check is to put a watt meter on it and strap the hex to the ground and run the throttle up and make sure that even at its max it doesent exceede the esc/motor amp rating. Also feeling by touch or thermometer after the test as most esc's will go into thermal shutdown mode in mid air if your too hot. Id definately re-tune PID's on each prop size and find that sweet spot that feels the best to you.

I personally run the 4" when i want to cruise around and want to stay in the air longer, then switch to the 5.5" when I want it to move on out but give up flight time.
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Old Jul 15, 2014, 06:48 PM
Beware Of The Shills !!!
Chichester Sussex
Joined Aug 2007
2,446 Posts
Quote:
Originally Posted by AIRFED View Post
I personally run the 4" when i want to cruise around and want to stay in the air longer, then switch to the 5.5" when I want it to move on out but give up flight time.
OK, this is the bit I was really interested in, I'm not bothered about screaming around the sky with this particular machine, so is it a given that less pitch will give more flight time do you know??
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Old Jul 16, 2014, 04:14 PM
Registered User
United States, LA, Shreveport
Joined Jul 2013
144 Posts
Quote:
Originally Posted by Witterings View Post
OK, this is the bit I was really interested in, I'm not bothered about screaming around the sky with this particular machine, so is it a given that less pitch will give more flight time do you know??
Increasing the pitch will increase the amp draw which will pull more battery over time. There are diminishing returns on either side but going from a 4 to 5.5 will cost you. Keep in mind all things being equal, so going from a slow fly 4 to a graupner 5.5 will result in ambiguous results. I assume we're talking about the same types of props which is really important. There are some good pitch and prop articles in this forum and on google, the good ones are relatively similar and I'd suggest checking them out.
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Old Jul 16, 2014, 11:44 PM
Soon to be CrashMasterPhil
Rochester MN
Joined Dec 2007
702 Posts
Did you state what size battery you're running. I guessing you should be 6s with the 380kv? And yes, you need some 13" props.

Quote:
Originally Posted by AIRFED View Post
Increasing the pitch will increase the amp draw which will pull more battery over time. There are diminishing returns on either side but going from a 4 to 5.5 will cost you. Keep in mind all things being equal, so going from a slow fly 4 to a graupner 5.5 will result in ambiguous results. I assume we're talking about the same types of props which is really important. There are some good pitch and prop articles in this forum and on google, the good ones are relatively similar and I'd suggest checking them out.
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Old Jul 17, 2014, 08:45 AM
Dirty Side Down.......o~^o
Hiway's Avatar
United States, MD, Sharpsburg
Joined Mar 2014
678 Posts
bump-
Quote:
Originally Posted by Hiway View Post
I am curious about how all the builders of this frame addressed one issue- the stationary arms distance and length.

There is a listed measurement on the schematics of the frame from the factory- I forget the exact measurement and from which points it is taken, but since I have an issue with yaw, I am wondering if this is where it is happening as opposed to tuning.

Some base info:
Tarot 680 stock ironman version with aluminum arms running SS 3508-380kv's and 11x4.7 props
Pixhawk FC with 3D external compass mounted directly above FC on post per requirements to separate them.

My problem: Yaw "floats" first CW and then CCW and is sporadic with no real consistency but it is almost constant. It isn't always on the move- but given a few seconds or a minute and it will yaw- holds position in loiter like a rock- but will slowly turn back and forth.

I have leveled, and releveled the motors suspecting that was the problem- I have not done much tuning to the pixhawk and it is basically stock settings which I am sure are not appropriate for this rig- but it does fly well and lifts off at 50% throttle evenly and with authority... I am getting 23 plus minutes of hover time albeit with the hex rotating back and forth- I want to begin tuning, but I need to be sure that I have basics right first or it will be a digressive endeavor.

I have noticed that some hexarotors seem to have the 2 side motors almost at a shorter distance- but that could be an optical illusion in the pics... basically I am making sure that all 6 motors should be the same distance from center and not some value less. This is my first hex, so I am not familiar with flight characteristics or tuning... I also have no prior experience with the Pixhawk.

Any insight or advice is appreciated.
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Originally Posted by divemasterphil View Post
Did you state what size battery you're running. I guessing you should be 6s with the 380kv? And yes, you need some 13" props.
I run 6S with 380kv's and the 11x4.7 APC slowfly props net me 20 minute flights lifting an 8000lipo and an AUW of 3.5kg on this frame- stock arms.
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Old Jul 18, 2014, 07:19 PM
Registered User
Norway, Vestfold, Larvik
Joined May 2012
87 Posts
todays flight.. something went way wrong
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Old Jul 18, 2014, 07:26 PM
Registered User
Joined Feb 2013
638 Posts
Quote:
Originally Posted by Hiway View Post
I am curious about how all the builders of this frame addressed one issue- the stationary arms distance and length.

There is a listed measurement on the schematics of the frame from the factory- I forget the exact measurement and from which points it is taken, but since I have an issue with yaw, I am wondering if this is where it is happening as opposed to tuning.

Some base info:
Tarot 680 stock ironman version with aluminum arms running SS 3508-380kv's and 11x4.7 props
Pixhawk FC with 3D external compass mounted directly above FC on post per requirements to separate them.

My problem: Yaw "floats" first CW and then CCW and is sporadic with no real consistency but it is almost constant. It isn't always on the move- but given a few seconds or a minute and it will yaw- holds position in loiter like a rock- but will slowly turn back and forth.

I have leveled, and releveled the motors suspecting that was the problem- I have not done much tuning to the pixhawk and it is basically stock settings which I am sure are not appropriate for this rig- but it does fly well and lifts off at 50% throttle evenly and with authority... I am getting 23 plus minutes of hover time albeit with the hex rotating back and forth- I want to begin tuning, but I need to be sure that I have basics right first or it will be a digressive endeavor.

I have noticed that some hexarotors seem to have the 2 side motors almost at a shorter distance- but that could be an optical illusion in the pics... basically I am making sure that all 6 motors should be the same distance from center and not some value less. This is my first hex, so I am not familiar with flight characteristics or tuning... I also have no prior experience with the Pixhawk.

Any insight or advice is appreciated.

It's a tuning issue. You can configure the arms to be in all sorts of weird distances from the body, as long as the FC knows about the positioning, it will know how to fly the copter.
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