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Old Sep 10, 2012, 06:08 PM
Grrr :-)
nerys's Avatar
Levittown PA 19057
Joined Aug 2006
435 Posts
no the board still knows "up from down" the props are just bits of plastic there is no programming in the props. so why you would think swapping the props would be the same as flipping the board is curious to me.

I want to flip the board so it thinks its right side up (because the board WILL be right side up)

try it without swapping the props. just hold it upside down and throttle up a bit. you will hear it scream and fight your hold trying to "right" itself.

I even tried hanging it from a string upside down and the moment I applied power it "flipped over" or tried too (tangled with the string of course)
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Old Sep 10, 2012, 06:13 PM
RC beginner
New York
Joined Oct 2008
5,622 Posts
Quote:
Originally Posted by nerys View Post
no the board still knows "up from down" the props are just bits of plastic there is no programming in the props. so why you would think swapping the props would be the same as flipping the board is curious to me.
because swapping props to other motors does just that.

anyway like i said turning a prop around (no swapping) reduces but does not reverse direction of thrust. so that should not have any effect on stability but you say it did.

btw is the udi known for sure to have accelerometer in addition to the gyro? do you know the part number? your mention of gyros is what threw me off because they cannot tell up from down. but that should not make any difference.
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Last edited by dave1993; Sep 10, 2012 at 06:30 PM. Reason: flipping prop does not change thrust direction
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Old Sep 10, 2012, 06:43 PM
Grrr :-)
nerys's Avatar
Levittown PA 19057
Joined Aug 2006
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you know you're absolutely right gyros can only sense relative motion not absolute position so it must have an accelerometer because the clearly knows up and down

I will post a video later
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Old Sep 10, 2012, 06:53 PM
RC beginner
New York
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i cant view flash videos and doubtful they would demonstrate anything. but a closeup of the board or chip numbers would be more important anyway.

and most important do you realize that turning a prop around has no effect on direction of thrust? this is key to our discussion.
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Old Sep 10, 2012, 07:49 PM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,266 Posts
Gents,
The UDI U816 does in fact have a Ivensense MPU 6050 3-axis gyro + 3-axis accelerometer, so yes the board must be mounted and flown as it it in the U816 or right-side up.. Not sure exactly what you are trying to do, but you could mount the motors upside down on the arms. You would have to insure the motor direction was the same and the props were flipped to properly force the air down, so the "top of the prop" is facing towards the motor when the motor is inverted. Since the motor rotation must be reversed to move the props in the same direction, you must also swap the CW and CCW props orientation from the normal arm positions or in other words to the other axis. The reason the motors must turn in the same direction when inverted is the code is using that motor direction on the arms in the code to yaw properly and hold heading. This has been done successfully in the last 10 years with many other quads flight controller boards. Clear as mud I'm sure...but hope that helps...
Cheers,
Jim
Quadrocopter and Tricopter Info Mega Link Index
Quote:
Originally Posted by nerys View Post
you know you're absolutely right gyros can only sense relative motion not absolute position so it must have an accelerometer because the clearly knows up and down

I will post a video later
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Old Sep 10, 2012, 09:43 PM
Grrr :-)
nerys's Avatar
Levittown PA 19057
Joined Aug 2006
435 Posts
I just wanted to see if it could hover upside down. IE I was curious why no one has made a 3D quad. something like a 929 probably would not work. To much inertia for direct drive (props too large)

but something like the u816 and the LB style direct drive tiny props type quads low inertia in the props COULD bring the motors to a stop and reverse rotation fast enough to go "inverted"

from the way I understand it this would all have to be done in programming IE the unit would have to make "changes" in what equals what so you could actually control the darned thing :-) but it should be very doable.

for me? heck no I can barely keep the thing inside a 3x3ft square FORGET a 3x3x3 cube I am just not good enough yet :-)

my LB is so bad in mixing Z rotation and throttle I was seriously considering rigging up some genuine rudder pedals so my feet could so Z rotate and my left hand could just do throttle :-)

but I have seen people do some truly insane crap so the skill is out their. Just needs the programming.

of course ideally you would want a deeper "pitch" to the prop and a bit more "torque" so you could have a more efficient "two way" propeller.

yeah I checked the picture it looks like the manufacturer intentionally obfuscated the processor for some reason.

Sorry about the terminology confusion I was using "gyro's" as a catch all term for the methods it uses to "right" itself.

Full size
http://i.imgur.com/x6NTq.jpg

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Old Sep 11, 2012, 12:39 AM
Registered User
Joined Sep 2012
16 Posts
I learned so much from this post. You guys are awesome.

Here are some photos of my Syma X1 bumblebee. I really like it. It actually looks much better than the photo.

I am not really good at doing review. And I dont own other models that mentioned here. All I can say is that it is easy enough for newbie like me to fly and enjoy it. It seems to be durable too, I have crashed it few times already. But still working as new.

Tried to fly it outside as well. Not a big fan of wind.

Overall, I am satisfied with the quality/performance and the money I spent.

I hope to keep learning new tricks here.
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Old Sep 11, 2012, 07:52 AM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,266 Posts
N,
A sustained upside down multicopter hover would only be possible with a collective or variable pitch setup. Some Gents have been experimenting with this. The irony is that the added complexity and expense of such a system makes it a bit less likely for one to want to go out and possibly destroy it attempting 3d flight

Form the Project Quads/Hexas/Octos section in the
Quadrocopter and Tricopter Info Mega Link Index

--Variable Pitch Quad builds: Variable Pitch Quad build by Redfox74 and his Multipilot board using variable pitch heli blades and three in-line motors running the shaft driven props: http://www.rcgroups.com/forums/showthread.php?t=1187308 and http://www.rcgroups.com/forums/showthread.php?t=1211064, Variable Pitch 2-Meter Quad build by Arrio: http://www.rcgroups.com/forums/showthread.php?t=1222990, Variable Pitch Multicopter Development by Outsider787: http://www.rcgroups.com/forums/showthread.php?t=1189826 , National Chong Kung University Taiwan (R.O.C) collective pitch: http://www.rcgroups.com/forums/showp...96&postcount=3 , MIT's variable pitch quad: http://www.youtube.com/watch?feature...&v=VIkqqVr_u9U
Cheers,
Jim

Quote:
Originally Posted by nerys View Post
I just wanted to see if it could hover upside down. IE I was curious why no one has made a 3D quad. something like a 929 probably would not work. To much inertia for direct drive (props too large)...
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Old Sep 11, 2012, 09:08 AM
Take flight
jameschen072's Avatar
Joined Aug 2004
2,165 Posts
I did a review on the Walkera V2... Questions and comments are welcome! =]

a tiny tiny video I made can be found here regarding the V2's precision in flight.
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Last edited by jameschen072; Sep 11, 2012 at 09:34 AM.
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Old Sep 11, 2012, 10:21 AM
RC beginner
New York
Joined Oct 2008
5,622 Posts
Quote:
Originally Posted by nerys View Post
I just wanted to see if it could hover upside down. IE I was curious why no one has made a 3D quad. something like a 929 probably would not work. To much inertia for direct drive (props too large)
atually just the opposite. we are talking muliticopter here so prop efficiency is far more important and since the dd quad is 1/3 to 1/2 that of mqx types theres little chance of flying one upside down. doubtful it could be done even with the big ones.

and since you seem to be ignoring my comment about backwards prop not changing thrust direction im guessing youve figured out that your flips have nothing to do with firmware, gyros, or accelerometers. if the udi props were actually symetrical like you think simply reversing them would allow it to fly.
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Old Sep 11, 2012, 12:26 PM
it was just a bumpy landing...
jlcamp7's Avatar
United States, WV, Hurricane
Joined Jan 2010
2,735 Posts
just another canopy I ran across on ebay that would work for the v929/mqx and probably any other model in that size range. Kind of cool looking. Comes clear so paint the way you want. However, I really like the way they painted. I wish they would sell them prepainted for a decent price.

ebay canopy
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Old Sep 11, 2012, 12:40 PM
it was just a bumpy landing...
jlcamp7's Avatar
United States, WV, Hurricane
Joined Jan 2010
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I agree with earlier post that it would be nice to keep seeing some other canopy options that actually felt like a hobby grade item. I'm not complaining but all these star wars knockoff's, smiling bee's and sad/angry ladybugs just really ruin the look of these quads. I mean the reality is the technology of these aircraft is absolutely unblievable. This is crazy technology and then you slap a weird plastic ufo on it. There has got to be something that makes this look more like a hobbygrade item.

It's like doing this to a ferrari
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Old Sep 11, 2012, 12:48 PM
Safety : practice & promote!
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Joined Dec 2011
4,300 Posts
To each their own, I say! I think that once the manufacturers catch wind of all of these custom canopies AND the apparent demand, they might step up to the plate. We'll see!
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Old Sep 11, 2012, 01:04 PM
it was just a bumpy landing...
jlcamp7's Avatar
United States, WV, Hurricane
Joined Jan 2010
2,735 Posts
Holy Crap! Has anyone seen this?



Just popped up in the deal section on rcgroups:
http://www.rcgroups.com/forums/showthread.php?t=1730133

Brushless motors! and 6 axis

Who knows how well it flies, but this is exactly what I was talking about when I was talking about not looking like a cheap toy. Now this looks like a nice piece of technology.
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Old Sep 11, 2012, 01:05 PM
it was just a bumpy landing...
jlcamp7's Avatar
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Joined Jan 2010
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Already sent info in hopes to get a hold of one for review.
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