Retractable Landing Gear Question

J

jhardway

Member
I am in the midst of putting together a new Tarot x8 (frame name its really a octo)m super nice frame. The frame comes with Tarot electric retractable landing gear. I have not build any copters with retracts before, but I have seen videos showing people having issues when they tie thethe landing gear power system in with the main power system.

I have seen video showing when the gear is powered all together and the retract are activated, it caused the copter to crash because the draw on the system somehow dipped the voltage below the ESC minimum voltage cut off.

My question,
Is there reason to worry about powering the retract gear with main battery or is it better to power the gear on its own battery.


Any advice or information is welcomed.

thanks all. Jack
 

Carapau

Carapau

Tek care, lambs ont road, MRF Moderator
The main thing is to ensure that the FC and your receiver are getting a separate feed although they will all eventually get their power from the main battery. Or in otherwords put in a separate BEC for the landing gear.
 


Rotorfreek

Rotorfreek

Member
The main point is this...

What is supplying the 5V feed to power the retracts... Are they fed from the same place as the Fc? If so, change it. You only need them to bind up and you will overload the shaired BEC and brownout.

One BEC for the flight controller and reciever, and another for accessories. That way you won't ever drop out of the sky.

Well, not because of a power loss to the Fc anyhow!

Sent by my thumb, a trusty slave to my crazy mind. The above is the ramblings of a lunatic, and should be treated as such. Terms and conditions apply.
 

J

jhardway

Member
Thanks everyone

I just want to get back with you, Looking at the way the system lays out I believe they most likely have some type of regulator with the gear. Along with the 2 legs, and 2 motors, there is a junction box that takes a pwm feed from the receiver to active the lifting and dropping of the gear. The junction box on a separate feed, can take a battery ranging from 3s to 6s, and it works fine when you pull the power pin out of the receiver wire. The fact that its has the ability to take such a range of power there's got to be something that sends the motors a consistent power voltage.

I will always take feed back about this topic, since this is an area I do not have much experience at.

I am planning to try to do some type of test to see if there is a draw that takes place while spinning the motors, not sure exactly how yet but I am planning to do so.

If I know anything I will post back my results.

best Jack
 

J

jhardway

Member
first flight, for the time I separated out the gears power supply with a little 3s battery. The gear and the copter did fine. I may appear in the video for clips, I would say I'm a little dressed down. :)

 

SamaraMedia

SamaraMedia

Active Member
This is a timely thread Jack since I just ordered the same retracts for my DIY 900mm hex. I liked the junction box being able to take a 6s battery straight off the PDB. Let me know how they work, look pretty smooth in your vid.

Swapping out my NAZA for a SuperX starting tonight, we'll see how that goes.
 

Carapau

Carapau

Tek care, lambs ont road, MRF Moderator
It sounds as if it is wired just as the DJI retracts are in which case it shouldn't cause huge problems with your FC voltage supply. It shouldn't do that even if you are plugged into the flight packs- providing they are rated to a high enough C rating which for MRs is usually to a minimum of 15c constant.
 

dtw

dtw

KC1UAV
jhardway said:
first flight, for the time I separated out the gears power supply with a little 3s battery. The gear and the copter did fine. I may appear in the video for clips, I would say I'm a little dressed down. :)
Click to expand...

Love the X8 frame - just curious if that's as high as those retracts go, i.e. do they angle up like the arms, or is that it?

I always thought the reason for the arms angling up is for stability AND so they're out of the way of the camera. Then the manufacturers add the retracts, which only lift up parallel with the body instead of parallel with the arms, and once again, there's something back in the way of the camera... (well... unless you mount the gimbal a little lower and other mods).

Anyway, some retracts have adjustable travel - just wondered if those have that?
 

J

jhardway

Member
On the retract they do not go any higher but in general they should not cause to much of an issues on getting in the picture for a few reasons. A good amount of time you will be above what ever the subject is, the camera in these case will be pointing more downward then horizontal. If the camera has an wide angle lens on it you may have an issue. Also I have been making bigger copters for the reason to make something that can carry more then a goPro style camera and its ultra wide results. Also when shooting a good amount of the time you will be shooting forward and with a horizontal to downward area. Over all in the past with my other octo I have not had many issue with the arms, etc..

Angling the arms and not getting in the camera's view is an added benefit to the reason why. The angling is called dihedral or the dihedral effect and its for a stability reason. On an airplane you will see the area that attaches to the fuselage is lower the end of the wing. Real basic but if you had an airplane out in the sunlight and you the sun was directly above you, the planes shadow coming off the wings would be equal, now if you roll the airplane to the right a until the right wing became horizontal with the ground and measured the shadows, you will see that the right wings shadow would be larger then the left wing's.

dihedraleffect4.jpg

This difference in the shadows size is like the difference in lift you will gain for each side. The right shadow side would grow adding lift while the left side shadow would be smaller, taking away lift. At this point if you had your controller stick in a neutral position the copter will want to correct itself to a equal state, making for a better stability.

I am not sure if I am to the one to even touch this topic and it goes way deeper then that, but at its very basics, this is how I thought I could give a decent idea of the concept.

In my video of the copter as I am going back and forth in the picture you can kinda see what I am getting at. In each move you can see how responsive it copter is at leveling itself off.

I have done the same with a straight arm frame, at this weight, and gains. I definitely see a difference in its stability, actually in controlling landings and taking offs of the copter.
 

dtw

dtw

KC1UAV
Right, agreed. I have/fly an S1000+, which is similar and very stable... and like I said in my post, it's for stability and they're out of the way of the camera. On my M680, my retracts are in the way, sometimes... My camera person complains about it (a.k.a. girlfriend), as she operates the gimbal. It's not always an issue, but according to her, only at the most inopportune times... :)

The Tarot X8 is very similar to the S1000 or S900 in so many respects, I just wondered if the retracts were adjustable - some of them are, i.e. http://www.arrishobby.com/landing-s...rc-multicopter-retractable-landing-skid-p-954

Thanks for the explanation though! :)
 

J

jhardway

Member
dtw

no worries I did not know how in depth you where you were in your copters, I will take a good look at the gear over the next day and let you know but my over all I am pretty sure there is not an adjustment, but also my camera is hanging pretty decent below them.

best
 

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