i have built a quadcopter using ducted fan with 400g thrust each, my quadcopter only weight about 750g,but it doesnt even lift off at half throttle only at full throttle. anyone have any suggestions on wat wrong or how i can improved it? my battery is charged btw.
Those thrust numbers are undoubtedly assuming horizontal mounting and higher speed, therefore greater efficiency.
I'm not any kind of an expert on this, but there have been many discussions here and at rcgroups about using ducted fans in a horizontal configuration.
You will need to provide more data such as:
A photo or two would help..
i used this ducted fans http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=...
apm1 and a 2cell 2000mah
i calculated and they are supposed to be able to carry a copter of 1kg. i tried decreasing the weight and it can fly now but not very high. but it spins, i dont understand why since i thought torque effect of ducted fan should be negligible?
Since torque isn't used to control yaw the EDF's must be installed at an angle so thrust controls yaw.
The instructions (control board) show proper prop rotation, rotate the EDF angle. If the prop rotates clockwise rotate the EDF clockwise, if the prop rotates counter clockwise then rotate the EDF counter clockwise. If the yaw gets worse the the rotation is opposite. Adjust angle of rotation to get the desired yaw control, 5 degrees would be a good starting point.
Since you are not using counter-rotating EDFs (i.e. all the props rotate in the same direction), are all the EDFs oriented at the same angle (relative to the vertical axis of the quadrotor)? I observed that the EDFs pairs on your quadrotor in the video seems to be oriented in opposite direction?(or is it due to camera's distortion?)
Also could the traditional control for yaw (based on counter-rotating props) be used without much modification? OR do you actually have to write your own control code for using the EDFs in your quadrotor? I guess I can just use a HK's KK board for the control ?
Hi Fun Wey,
All of the control boards have a diagram for prop rotation when looking down from the top, to achieve proper angle for the EDF's put an arrow on each boom showing the rotation for each motor then rotate the EDF in the same direction. People ask how long it took me to figure out the proper angle, about 5 minutes, my first try works so well I didn't make any changes. It only takes a couple of degrees to neutralize the torque of a prop (observed on my tricopters) so 5 to 7 degrees should be a good starting point. I don't know what the angle on mine are, I can't find my clinometer. If it is hard to yaw increase the angle, if it spins then the angles are reversed. The EDF's don't like ground effect so it needs to get about 3 feet off of the ground before it settles out. As you gain altitude less power is required to maintain flight. Not for the beginner. Don't try to fly it in the dirt, unless you like a layer of soil on everything in twenty feet.
No changes to software or code and since it is so stable stock PIDs on the Paris board work fine.
Good luck, Ed
Thanks for the info. BTW have you done aerobatics with the EDF rotor? I wonder if any of the controllers could help with the flip, or do we have to switch it off ?
Ducted fan quadcopters do work, not knowing any details I can't provide advice. You probably need to increase the cell count on the batteries, mine acts like your description on 4 cells but flies very well on 6 cells. If the ESC's are not sized properly they will overheat and shut down.
i tried increasing from my 2cells to a 3cells but the ducted fan shut down on its own when i go more than half throttle. its so stubborn its like telling me only a 2cells will do.
You need at least 30 amp ESC's, I had to use 60 amp ESC's with 90mm EDF even though they don't draw that much current. I think my 60mm EDF has 40 or 45 amp ESC's.
hey do you know whether number of blades on a ducted fans matters? for example two ducted fans of the same dimemsion and kv but one with 8 blades and other one with 6 blades, are there any differences? cus i orignally wanted to buy ducted fans with 6 blades for my tricopter,but there are only with 8 blades, so want to ask for your opinion.