Drone crashed after using RTH

[fiberdude]

A parabolic reflector is analogous to a reflector in a car headlight or flashlight, it reflects and focusses the RF.

Can you tell us about the wavelength of visible light, Prof With-the-birds?

 

[fiberdude]

Look at the physical dimension of a satellite dish for 12-14 Ghz EM transmission -- you will see the dish size is at least an order of magnitude larger than the wavelength of the EM transmission, @With The Birds :

 

[With The Birds]

Look at the physical dimension of a satellite dish for 12-14 Ghz EM transmission -- you will see the dish size is at least an order of magnitude larger than the wavelength of the EM transmission, @With The Birds :

View attachment 94356

This is a different configuration again, it employs a wave guide as the driven element. It might help you to understand that your thinking on this is off- simply because it will still perform well over a very wide frequency band, you can even fit multiple feed horns without issue- what is important is that the feed horn are at the focal point of the dish.

I know what the wavelength of light is. What’s your point? Forget RF for a second, stick a microphone at the focal point is a reflector and you will get gain.

 

[fiberdude]

The point being: the visible light has wavelengths about 390–700nm, which is 6 orders of magnitude smaller than the size of the reflectors in the car or in the flashlight. Thats how reflectors of EM waves would work. If the reflectors are about the same size as the EM wavelength, you need to study wave diffraction etc, not reflection. Perhaps its a good idea for you take a course on how to solve the set of four coupled Maxwell equations in 3 dimension

This is a different configuration again, it employs a wave guide as the driven element. It might help you to understand that your thinking on this is off- simply because it will still perform well over a very wide frequency band, you can even fit multiple feed horns without issue- what is important is that the feed horn are at the focal point of the dish.

I know what the wavelength of light is. What’s your point? Forget RF for a second, stick a microphone at the focal point is a reflector and you will get gain.

 

[Russ43Phantom]

I fly my P4P with multiple devices: (1) BT-300, (2) iPhone X, and an iPad. Updating software in the device DOES NOT change the settings like RTH altitude so automatic updates in device software should not have been an issue. The variables like RTH altitude, appropriately, are kept either on the drone or on the RC Controller.

I also learned, that, for the P4P, collision avoidance does not work with leafless branches. Another important consideration, which DJI won’t acknowledge, is that in many cases, the RTH altitude must be set to a MAX altitude vs. a MIN altitude. Here in NH, I often fly under a canopy of tall trees. I need to set my RTH altitude to 30’ to avoid flying directly up into the over hanging branches.

 

[With The Birds]

The point being: the visible light has wavelengths about 390–700nm, which is 6 orders of magnitude smaller than the size of the reflectors in the car or in the flashlight. Thats how reflectors of EM waves would work. If the reflectors are about the same size as the EM wavelength, you need to study wave diffraction etc, not reflection. Perhaps its a good idea for you take a course on how to solve the set of four coupled Maxwell equations in 3 dimension

The larger the reflector the higher the gain obviously. And yes being larger than a wavelength is preferable but not necessary.

The windsurfers do work. You should try them

 

[RC Madman]

Sorry you crashed. I have learned over the years that we as pilots should never rely on settings staying "Set". I think it has been said a number of times in this thread "Preflight" which if done properly each flight saves many of us headaches. Always check your settings. Just assume that they are wrong before each flight and check them.

 

[fiberdude]

I fly my P4P with multiple devices: (1) BT-300, (2) iPhone X, and an iPad. Updating software in the device DOES NOT change the settings like RTH altitude so automatic updates in device software should not have been an issue. The variables like RTH altitude, appropriately, are kept either on the drone or on the RC Controller.

I also learned, that, for the P4P, collision avoidance does not work with leafless branches. Another important consideration, which DJI won’t acknowledge, is that in many cases, the RTH altitude must be set to a MAX altitude vs. a MIN altitude. Here in NH, I often fly under a canopy of tall trees. I need to set my RTH altitude to 30’ to avoid flying directly up into the over hanging branches.

See this dropbox clip (720p) -- The DJI OA system was able to detect those leafless winter branches, and moved the AC up (and backward) until re-establishing RC contact. Maybe the lighting condition was at optimal at the time for the OA.

 

[bsartist]

See this dropbox clip (720p) -- The DJI OA system was able to detect those leafless winter branches, and moved the AC up (and backward) until re-establishing RC contact. Maybe the lighting condition was at optimal at the time for the OA.

Heartstopping. Where was this filmed? Nice countryside.

 

[fiberdude]

Heartstopping. Where was this filmed? Nice countryside.

West Lake in China's finest city, Hangzhou (not exactly countryside -- the home point was very close to the evening concert of 2016 G20 Hangzhou summit).

 

[RémyHeli]

Impressive RTH manoeuver with negotiating obstacle and raising altitude in two steps

 

[bsartist]

West Lake in China's finest city, Hangzhou (not exactly countryside -- the home point was very close to the evening concert of 2016 G20 Hangzhou summit).

Surprised you were allowed to fly with all the security that must have been around. Surprised it wasn’t a no-fly zone.

 

[bsartist]

Impressive RTH manoeuver with negotiating obstacle and raising altitude in two steps

It looked like the second ascent may have been manual after he got RC control back.

 

[fiberdude]

It looked like the second ascent may have been manual after he got RC control back.

You are absolutely correct!

The second I saw on the phone the AC being so close to the tree branches I pushed left stick forward the backward move was not done by me, though. Movements other than ascent (and some horizontal motion) are not written anywhere in the manual

 

[fiberdude]

Surprised you were allowed to fly with all the security that must have been around. Surprised it wasn’t a no-fly zone.

It's barely outside the NFZ, and its a restricted zone with a ceiling of 120m.

 

[Droning in AR]

See this dropbox clip (720p) -- The DJI OA system was able to detect those leafless winter branches, and moved the AC up (and backward) until re-establishing RC contact. Maybe the lighting condition was at optimal at the time for the OA.

That's a beautiful piece of video there.

 

[sar104]

See this dropbox clip (720p) -- The DJI OA system was able to detect those leafless winter branches, and moved the AC up (and backward) until re-establishing RC contact. Maybe the lighting condition was at optimal at the time for the OA.

That worked nicely, but it's not clear that it was the small leafless branches rather than the abundant foliage in the field of view that triggered the OA.

 

[apprentice]

Copy that. I just didn't expect my settings to be changed. That's bad business on DJI by auto changing settings on updates especially without notification.

I'm sorry. I'm usually quite angry when I lose all of my settings. That happens.

But to avoid any damage I follow my Check list. And it's in my check list that I have to check Maximum altitude, Return to Home / Failsafe altitude, Compass, Battery temperature, Voltage of each battery cell, and lots of other settings. And when I'm flying after an update I always do a test flight. Test flight is just a short flight where I just check if everything works right.

 

[dcdogg]

Odd because I changed both to 120m and never changed it back. Something other than me changed it back. I never went back into those settings to default it back. In fact my last flight rose to 120 when I used RTH. Also the sensors didn't detect the tree or try to go higher to avoid collision. I never had any problem with RTH before this flight.

I'm hoping DJI will do something about this.

Good luck with dji doing anything.

 

[Anzacjack]

I think we have all experienced this in some way. We make a mistake and immediately look to blame someone else. But in the end the fact is "we made a mistake"
DJI are a company that revolves around making money. ALL companies are. They cant afford to fix all of our mistakes