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Old Oct 05, 2011, 06:42 AM
gravity is strong where I fly
Air Cooled's Avatar
United States, NY, Rochester
Joined Jul 2011
221 Posts
Quote:
Originally Posted by 4x4rc View Post
It has been mentioned and a search would have shown you this:

http://www.rcgroups.com/forums/showt...h#post16103745
What he did barely resembles what I was asking about, but thanx for pointing it out.
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Old Oct 05, 2011, 07:26 AM
RC Airplane (Recently Crashed)
mutha's Avatar
Australia, VIC, Melbourne
Joined Jan 2011
2,949 Posts
Quote:
Originally Posted by RoboSerg View Post
Flew again for 13 mins before aileron servo burned up What I noticed is that I cant do rolls like I saw on youtube. Thats why I want to extend aileron movement. But I dont understand what do you mean with "set up mechanical or radio (subject to your setup) differential." Could you explain little bit more?

On the TX I can extend the channel range, this should help doesnt it?- NO
Plagerised for speed ...
Aileron differential is usually applied on models having a non symmetrical airfoil such as hotliners, gliders, pylon racer and DLG rc planes. The up moving aileron moves more than the down moving aileron to account for the difference in lift and air pressure on the top and bottom wing surfaces. The ratio is generally 3:2 or slightly more.
A simple explanation of Aileron Differential is when the aileron of a plane goes up more distance than the down aileron to achieve the same deflection and with this adjustment, your airplane will roll in a perfect axial.


This can be achieved with a mechanical setting of the servo arm and control rod or with two servos on different chanels via a radio that can program dual chanel ailerons (Dx6i Dx7 ... and heaps of others).
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Old Oct 05, 2011, 08:01 AM
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Joined Sep 2011
478 Posts
My Turnigy ESC 25a just arrived. However if I plug everything in, the motor beeps like so "beep beep, pause, beep beep" and the prop jitters back and forth by an inch. What is wrong? If I plug another ESC it initializes well.

I also had to replace one aileron servo, but now ailerons go same way, but they should go opposite. I want to place new servo exactly same way the burned one was, due to wiring. I actually cant put in another way. But now flaps go to same direction, disabling turns (capt obv). Is there a way to make servo turn another direction? These are aileron servos hanging on Y wire.

Oh and one of two new servos actually jitters at neutral. Is that ok? Other 3 servos dont jitter at neutral, however they all jitter at max angle.
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Old Oct 05, 2011, 08:55 AM
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JLT_GTI's Avatar
Oviedo
Joined Jun 2010
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Quote:
Originally Posted by RedLine19k View Post
As for why the 6x5 prop pulls less amps, it is stalled and simply beating turbulent air. Static testing on props over 2/3 pitch diameter ratio is problematic for this reason. The rpms are likely higher on the 6x5 than the 6x4, but it's actually moving less air. At the 20 or so mph it became unstalled, amps would increase.
So does that mean that in flight power drain will actually increase? Should the 6X4 be expected to go down?.. 313W (and the 297 of the 6X5 wich may go up in flight) is really close to the 340W power limit of the 2212-6/2826-6 motor.. the funny part is that im using a 6X4 there wich is the all-recomended prop for this motor .. and tons of people use this motor in parkjets and planes with 6X4.. even some people are reporting using 6X6 in funjets and wings and they say it goes well...reporting loads of arround 25/26A (wich is pretty close to my static 6X4 tests)

Also the 5X5 pulling 269W is due to suffer from stalling in static too? is that figure realistic?


Quote:
Originally Posted by RoboSerg View Post
My Turnigy ESC 25a just arrived. However if I plug everything in, the motor beeps like so "beep beep, pause, beep beep" and the prop jitters back and forth by an inch. What is wrong? If I plug another ESC it initializes well.
Maybe you have to reverse the throotle channel or you have to set the throotle max and min by pluging the battery with the throttle at max and when it beeps after the first "wellcome" melody (before it beeps one time for each cell detected) go idle and it should arm (3 beeps in 3S and a long beep to indicate ARMED)
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Old Oct 05, 2011, 09:16 AM
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Joined Sep 2011
478 Posts
I also have troubles with servos. After I crashed one aileron servo broke, it was only jittering at neutral and not moving. I took the rudder servo which worked just fine, placed it into aileron holder, but now this servo jitters at neutral too and doesnt move! But it was working 2 min ago. Makes me crazy. Other servo I have go in the wrong direction Whats up with jittering? Is the servo dead? And how do I reverse servo direction without TX. Because now I have ailerons going same way with other spare servos (( Do I solder two wires that go to the servo other way around to give it opposite direction? Or are there cw and ccw rotation servos?
Oh and I cant move the arm of those jittering servos. Seems like the gear stuck. But why does it happend?

Also how should the prop be mounted. With the numbers 5x5E facing the nose or the tail? If its the nose, than the washer falls out.

Also where exactly should be the center of gravity.

Quote:
Originally Posted by JLT_GTI View Post
Maybe you have to reverse the throotle channel or you have to set the throotle max and min by pluging the battery with the throttle at max and when it beeps after the first "wellcome" melody (before it beeps one time for each cell detected) go idle and it should arm (3 beeps in 3S and a long beep to indicate ARMED)
Thank you very much. I had to set the range. Thx
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Old Oct 05, 2011, 11:41 AM
Dance the skies...
Tom Frank's Avatar
United States, MA, Walpole
Joined Dec 2003
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Quote:
Originally Posted by RedLine19k View Post
The blade angle varies along the length, but the pitch is close to constant. The tips of the blade travel much farther than the root, so the angle of attack is much less. Any given section would drive the prop forward the same distance in 1 revolution "geometric pitch" tho the "effective pitch" is less due to slippage in air.
...
Blade angle and angle of attack are two different things, but my main the point was that two different brand props that have the same diameter and pitch printed on the blade don't necessarily have the same exact diameter and exact same blade twist at each section of the blade, not to mention different blade airfoils and chord length at each section, so they should not be expected to perform the same on the bench (with portions of the blade also stalled), or in the air.
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Last edited by Tom Frank; Oct 05, 2011 at 11:51 AM.
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Old Oct 05, 2011, 12:03 PM
Registered User
United States, OH, Youngstown
Joined Nov 2004
593 Posts
JLT its difficult to predict because a lot of factors are changing at once. As the prop unstalls, amps increase. This is known by the LMR guys using square or oversquare props. But as the plane accelerates, the load on the prop is gradually reduced. This unloading will continue up to the max speed of the plane (drag=thrust). The difference between this speed and the pitch speed (i.e. slick airframes can unload more). Battery voltage is also continuously dropping, which may completely offset or mask the prop rpm increases due to unloading.

What you would expect to see, at constant throttle setting, is the voltage staying the same or decreasing but rpms increasing. The problem is, as the prop unloads, amps decrease, which can cause battery voltage to rebound.
And the motor is heating up. And it's very difficult to tell is the plane is level - and everyones heard props unloading in a dive.

These guys did a very good job trying to answer the question. Post 117 has a great graph that shows watts drop as speed increases. It also shows a vertical climb pulling as many watts as static.

6x4 with the 2212/6 is a very proven setup. There's so many variables (better batteries, Kv variance, different brand props, airframe etc) it would be impossible to predict your exact setup. but it's pretty easy to check with a datalogger. You might also find on draggier airframes, that the 6x5 might have similar top speeds, more amp draw but worse acceleration than a 6x4. This is assuming the props are the same brand and type, like you mentioned.

I plan on using a 2212/6 on the Cloud Fly. If i get some datalogs of 6x4 and 6x5 APC-E and TGS props i'll post them here with gps speeds.
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Last edited by RedLine19k; Oct 05, 2011 at 12:13 PM. Reason: forgot link
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Old Oct 05, 2011, 01:24 PM
Just thumbing through...
victapilot's Avatar
United States, SC, Simpsonville
Joined Feb 2009
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Redline, that would be great to have some loggers data. There's no doubt about unloading, everyone that flies glow knows it. I look forward to see your numbers.
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Old Oct 05, 2011, 04:12 PM
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One bit of lame question about all of this...

If the stock 2208N 2100Kv (some sources say 2150) CloudsFly motor at WOT with a 5X5 draws lets say 18.5A .. and the 2212 2200Kv with same prop draws 22.5A ..

Should i asume im getting more RPMs and so more thrust/speed or the motor may be burning that excess power in heat or some other loose and that gain not be real? Or electric motors are that trusty in numbers? (i dont know if im expressing well.. sorry)
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Old Oct 05, 2011, 04:28 PM
Just thumbing through...
victapilot's Avatar
United States, SC, Simpsonville
Joined Feb 2009
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Most likely you get more rpm and more power with the second motor. Easy to check with a tach. It's not impossible that a bad motor, eg wit displaced magnets, could draw more power due to innefficiency, but if both motors good, that's rare

It's possible to get RPM from a WAV file using Winscope. Many references to it on RCG, it's a free download
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Last edited by victapilot; Oct 05, 2011 at 04:57 PM.
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Old Oct 06, 2011, 07:13 AM
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Something i tought while planing the setup for the HawkSky (and its cooling actually)..

In the Clouds we have 2 air intakes in the nose and a big exaust in the rear.. principles say where the planes moves forward the air is forced into the front intakes and will exit throught the rear after streaming all internal components (more or less)..

I tought.. the rear exaust outtake is just in front of the propeller wich moves air backwards.. could the propeller be also creating an effect where it would be forcing air out of the fuselaje as well (wich would also force air inside from the front intakes) ?
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Old Oct 06, 2011, 07:21 AM
flying or crashing into air?
wizzard363's Avatar
Australia, VIC, Langwarrin
Joined Feb 2011
1,336 Posts
Hi guys
I want to add a pitch gyro to my cf using a Detrum GY48V
What channel do I use to set the gain and how do I set it on the DX6i ?.
In the heli setup it uses the flap/gyro switch but in the plane setup I have no idea what to use for gain.
Any help would be great thanks


EDIT I found these vids that explain everything http://www.mycoolrc.com/gyro/ruddergyroinstall1.html
I will leave this post as it may help others
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Last edited by wizzard363; Oct 06, 2011 at 07:54 AM. Reason: Found the info needed
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Old Oct 06, 2011, 09:09 AM
Argue for your limitations
ajbaker's Avatar
Lincoln, CA
Joined Oct 2006
8,422 Posts
Quote:
Originally Posted by RoboSerg View Post
I also have troubles with servos. After I crashed one aileron servo broke, it was only jittering at neutral and not moving. I took the rudder servo which worked just fine, placed it into aileron holder, but now this servo jitters at neutral too and doesnt move! But it was working 2 min ago. Makes me crazy. Other servo I have go in the wrong direction Whats up with jittering? Is the servo dead? And how do I reverse servo direction without TX. Because now I have ailerons going same way with other spare servos (( Do I solder two wires that go to the servo other way around to give it opposite direction? Or are there cw and ccw rotation servos?
Oh and I cant move the arm of those jittering servos. Seems like the gear stuck. But why does it happend?

Also how should the prop be mounted. With the numbers 5x5E facing the nose or the tail? If its the nose, than the washer falls out.

Also where exactly should be the center of gravity.



Thank you very much. I had to set the range. Thx
Turn the servo over. CG is 50-55mm. I prefer 55mm on mine. The numbers on a prop are meaningless. Manufactures put them on either side of a prop. See pic below for proper orientation.
AJ
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Old Oct 06, 2011, 06:25 PM
4 Heli's, 1 Plane, & 1 Car
kashalp's Avatar
Canada, ON, Angus
Joined Mar 2010
171 Posts
Quote:
Originally Posted by wizzard363 View Post
Hi guys
I want to add a pitch gyro to my cf using a Detrum GY48V
What channel do I use to set the gain and how do I set it on the DX6i ?.
In the heli setup it uses the flap/gyro switch but in the plane setup I have no idea what to use for gain.
Any help would be great thanks


EDIT I found these vids that explain everything http://www.mycoolrc.com/gyro/ruddergyroinstall1.html
I will leave this post as it may help others
i too have been contemplating putting a gyro on my axn. Not for regular flight but mostly cause i am now experimenting with fpv on this model. Although i have been thinking about putting it on the ailerons rather then the elevator and/or rudder. Anyone else do this and if so how did it work out?
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Old Oct 06, 2011, 06:34 PM
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brace's Avatar
Australia, NSW, Ashby
Joined Jul 2011
219 Posts
I have a gyro from Hobby King hooked into the 'Y' lead for my ailerons. Works great and steadies the plane considerably. Found it was also great in preventing damage when taking off and landing in strong winds as the gyro reacts quickly to any gusts that threaten a cart wheel type action when close to the ground. I have been following the following thread on this and it is very informative.
http://www.rcgroups.com/forums/showthread.php?t=1035605
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