RTH question

Joined
Feb 22, 2017
Messages
426
Reaction score
135
Age
63
since i don't want to experiment i thought i'd ask the pros . If i take off and have RTH set to say 60 m and i fly up a mountain to an alt of lets say 900' above take off point . if RTH kicks in will the bird slam into the ground or will it know it's only 100' above hard ground even though the alt is 900' above take off ?
 
since i don't want to experiment i thought i'd ask the pros . If i take off and have RTH set to say 60 m and i fly up a mountain to an alt of lets say 900' above take off point . if RTH kicks in will the bird slam into the ground or will it know it's only 100' above hard ground even though the alt is 900' above take off ?
1. You should experiment with RTH.
The day you need RTH is the worst day to start learning how it works.

2. There's no way your Phantom can know how far it is above the ground beneath it.
It only knows that home = zero.
If it is below your set RTH height above home, it will rise to the RTH height you have set to come home.
If already higher than the RTH height, it will come straight home.
 
  • Like
Reactions: flyboy73
1. You should experiment with RTH.
The day you need RTH is the worst day to start learning how it works.

2. There's no way your Phantom can know how far it is above the ground beneath it.
It only knows that home = zero.
If it is below your set RTH height above home, it will rise to the RTH height you have set to come home.
If already higher than the RTH height, it will come straight home.
I've used RTH many times but never in the situation i described. so you're saying that if I'm higher then the preset RTH alt it will fly back and then descend . I'll give that a try but over flat ground
 
Just to clarify, when your home points sets in preflight your aircraft think that is ground zero regardless of your actual altitude above sea level. When it returns to home it will try to land back at the same altitude it took off from. Hope that's helpful
 
  • Like
Reactions: PhantomWetSuits
Just to clarify, when your home points sets in preflight your aircraft think that is ground zero regardless of your actual altitude above sea level. When it returns to home it will try to land back at the same altitude it took off from. Hope that's helpful
Rth works great use it often , just never when i was up a mountain side . Needed to know if i set RTH at 90m or 500m . Since it seems the drone will stay at alt above RTH alt until it get over home . going to go test it now
 
  • Like
Reactions: 3rdof5
I've used RTH many times but never in the situation i described. so you're saying that if I'm higher then the preset RTH alt it will fly back and then descend . I'll give that a try but over flat ground

As mentioned, the Phantom does not "land" (shut off the motors) based on it's altitude. When it lands on its own, it slowly descends until it's barometer tells it that it is no longer descending. It then shuts off the motors. It does not care if the barometer tells it that is is at 10' above the take off point, 1' above the take off point and 10' under the take off point... if it is flying downward and stops loosing altitude for a few seconds, it turns off the motors. Again, this would happen no matter what it stopping it. It could be an object such as being caught in your hand, because it is on the roof of a building, etc. it does not care what it's altitude above the home point is.

I'll add that, as mentioned above, the altitude it thinks it is at is.... based on it's altitude above _the take off point_, which is the home point. If you take off on a cliff and fly down, it will show that it is at a negative altitude. It won't think it's landing and shut off. It only senses when it's flying downward and _can't_ fly downward... that is, it stops for a descending for a few seconds. This is the trigger is uses to shut off the motors.
 
  • Like
Reactions: 3rdof5
I've used RTH many times but never in the situation i described. so you're saying that if I'm higher then the preset RTH alt it will fly back and then descend . I'll give that a try but over flat ground
I'm curious about this as well. Not too sure your question was answered to the point that it will not descend to RTH altitude before heading home. Please let us know what you find out.
 
I've use it since I started flying these things and I promise you it will turn and come home when you hit RTH.
Just say you are on flat ground .
If you are below what you have set say 60m it will rise first to that then come straight back .
If you are at 120m it will just turn and stay at that if you let it till it gets overhead then land.
If that don't make it clear I don't know what will other than using it and like Meta said not practicing with it and trusting it will get you in trouble.
But let me say this . I have mine at 40m . I went down a field about a mile at 20m and the field took a left .I continued down that field and lost contact . It did rise to 40 m but there was a hill between it and me and was more than 40m .Had I not made contact in the app I would have hit the trees on it but saw them in time to rise above them so just be aware of whats between you and the bird ,being a pole ,tower or whatever . Hope that makes it clearer .
 
What dirk says is spot on. In my opinion its ok to trust the aircraft to a point. However i think the most important part of the preflight planning is to scout ur surroundings first to learn what the safe altitude to fly at in any mode and use that for your default RTH altitude and avoid these issues entirely
 
  • Like
Reactions: MotorCycle-Man
I'm curious about this as well. Not too sure your question was answered to the point that it will not descend to RTH altitude before heading home. Please let us know what you find out.
I don't think I could have made it much clearer than:
If it is below your set RTH height above home, it will rise to the RTH height you have set to come home.
If already higher than the RTH height, it will come straight home.
 
All cleared up. Thanks for driving it Into my thick scull.
 
I've use it since I started flying these things and I promise you it will turn and come home when you hit RTH.
Just say you are on flat ground .
If you are below what you have set say 60m it will rise first to that then come straight back .
If you are at 120m it will just turn and stay at that if you let it till it gets overhead then land.
If that don't make it clear I don't know what will other than using it and like Meta said not practicing with it and trusting it will get you in trouble.
But let me say this . I have mine at 40m . I went down a field about a mile at 20m and the field took a left .I continued down that field and lost contact . It did rise to 40 m but there was a hill between it and me and was more than 40m .Had I not made contact in the app I would have hit the trees on it but saw them in time to rise above them so just be aware of whats between you and the bird ,being a pole ,tower or whatever . Hope that makes it clearer .
Very clear ! lol just asked a simple question . when above RTH alt does it descend to preset alt first . no it does not it flys back and then descends . i thought that's what it did but didn't want to chance it
 
  • Like
Reactions: dirkclod
Very clear ! lol just asked a simple question . when above RTH alt does it descend to preset alt first . no it does not it flys back and then descends . i thought that's what it did but didn't want to chance it
I was kinda addressing Maddy with my post as I saw you had already been answered. :)
 
I was kinda addressing Maddy with my post as I saw you had already been answered. :)
oh . i was wondering why all the in depth answers for such a simple question . i kind of knew this all ready but getting old brain and spaced it out . came here for a refresher
 
  • Like
Reactions: dirkclod
I don't think I could have made it much clearer than:
If it is below your set RTH height above home, it will rise to the RTH height you have set to come home.
If already higher than the RTH height, it will come straight home.
Meta4, in no way was I criticizing your response, but I still needed a bit more clarification to the question. Being new to drones I find myself questioning and analyzing all of the posts here to a point of probably conflicting confusion upon myself. When I read “straight home" I seem to have taken it too literally as flying diagonally to the point of the RTH height, thus descending during the stretch to reach the correct height above the home point.
 
Surrounded by trees and forest here in a valley, what you asked was one of my first questions. Did some short hop missions to verify that indeed it will maintain its last waypoint altitude till it arrives over the take off point, then descend and land.
 
Interesting discussion. I've used RTH but ive always been lower than my set altitude and it always rose to 35m and then came home. Didnt know what it did if you were higher than that when u hit RTH. Good to know now that it will maintain its current height if higher than the set point until its over home point :)
 
oh . i was wondering why all the in depth answers for such a simple question . i kind of knew this all ready but getting old brain and spaced it out . came here for a refresher
Think ya got it didn't't ya .lol:)
 

Members online

No members online now.

Forum statistics

Threads
143,066
Messages
1,467,358
Members
104,936
Latest member
hirehackers