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R.T.H Question

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#1
Wonder if any of you know - how - blokes could clear something up for me..
Scenario - I take off - climb 50 feet - fly over a cliff which has a 100 foot drop - my altitude now is 150 feet - I decide to press R.T.H which is set for 50 foot altitude.. Does the H now descend 100 foot and crash into the cliff or does it remember the altitude from where it took off regardless of the height when R.T.H is deployed.
I think I know the answer , guess I just don't want to find out the hard way.
Thanks.
 
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#2
The H will return to it's last take off point.

Edit by Moderator: The H does not return to the takeoff point. It returns to the location of the ST16.
 
Last edited by a moderator:

Steve Carr

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#3
Wonder if any of you know - how - blokes could clear something up for me..
Scenario - I take off - climb 50 feet - fly over a cliff which has a 100 foot drop - my altitude now is 150 feet - I decide to press R.T.H which is set for 50 foot altitude.. Does the H now descend 100 foot and crash into the cliff or does it remember the altitude from where it took off regardless of the height when R.T.H is deployed.
I think I know the answer , guess I just don't want to find out the hard way.
Thanks.
The altitude is set to zero when you start the motors. The H has no ground detection system and has no idea what the AGL might be. It's all relative to the takeoff point.
 
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#4
Wonder if any of you know - how - blokes could clear something up for me..
Scenario - I take off - climb 50 feet - fly over a cliff which has a 100 foot drop - my altitude now is 150 feet - I decide to press R.T.H which is set for 50 foot altitude.. Does the H now descend 100 foot and crash into the cliff or does it remember the altitude from where it took off regardless of the height when R.T.H is deployed.
I think I know the answer , guess I just don't want to find out the hard way.
Thanks.
My "H" remember the last RTH setting. I usually set it to 120ft. Enterprise, why do you set you RTH as low as 50ft? Not smart at all. You almost ask for a crash.
 
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#5
Wonder if any of you know - how - blokes could clear something up for me..
Scenario - I take off - climb 50 feet - fly over a cliff which has a 100 foot drop - my altitude now is 150 feet - I decide to press R.T.H which is set for 50 foot altitude.. Does the H now descend 100 foot and crash into the cliff or does it remember the altitude from where it took off regardless of the height when R.T.H is deployed.
I think I know the answer , guess I just don't want to find out the hard way.
Thanks.
The H takes into account Height, not altitude; In the assumed scenario the aircraft would climb to your preset height of 50 meters above take off height, regardless of the drop below

So no, the aircraft would not descend to return.

Greetings!
 
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#6
The H takes into account Height, not altitude; In the assumed scenario the aircraft would climb to your preset height of 50 meters above take off height, regardless of the drop below

So no, the aircraft would not descend to return.

Greetings!
JulesTEO, Enterprise wrote 50ft, not 50meter. ;)
 
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#8
Heights are always relative to the point that you take off from. If you fly up to 50 ft above your take-off position then you are 50 feet up in the air. If you then fly out over the cliff which is, say, 100 ft high you are still 50 feet above your take off position. BTW, the H will always climb up to your RTH height but never descend to it before returning home. If you have set RTH to 100 feet,say, and you initiate RTH at a height of 50 ft, then it will climb to 100 feet before returning. If you initiate RTH when you are at 150 feet it will return at 150 feet.

Incidentally, and loosely related. In the U.K. the law about heights is always based on the ground level that the pilot is standing on. For the recreational flyer (at present), the advised maximum height is 400 feet. That is 400 feet above the position of the pilot. This means that you can fly your aircraft up to 400 feet then fly out over a 200 foot cliff meaning that the aircraft is now 600 feet above the ground directly below the aircraft and still be flying within the spirit of the CAA's advice. If, however, you take off from the beach below the cliff the advisory 400 foot height limit means that you can't fly over the higher ground 200 feet up at 400 feet above that higher ground. The 400 feet advisory is related to the ground the pilot is standing on, not the ground the aircraft is flying over. In the U.K. the height rules are not terrain following.

Of course, for the commercial flyer the 400 foot rule is law and not an advisory.
 
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#9
Well, I was not in the opportunity to test this yet, but to my belief RTH is related to the altitude the controller is at the moment you switch it on, not the take off. So if you descended steeply during flight the RTH altitude may be different in terms of clearing natural obstructions then you would want it to be.

I think the autopilot makes a snapshot of the position of the controller @the time you flip the switch and it will act accordingly .


:)
 
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#10
Well, I was not in the opportunity to test this yet, but to my belief RTH is related to the altitude the controller is at the moment you switch it on, not the take off. So if you descended steeply during flight the RTH altitude may be different in terms of clearing natural obstructions then you would want it to be.

I think the autopilot makes a snapshot of the position of the controller @the time you flip the switch and it will act accordingly .


:)
I agree for X and Y but the ST16 does not contain a barometer so how could Z be determined? The Wizard does have an internal barometer but I think RTH height is a function of take off altitude as recorded by the H's on board barometer.
 
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#12
I do not know for sure.
Neither of us, if I understand correctly.

My two pennies worth seem more logical though. We agree RTH aims @controller, and switching to RTH will take a snapshot of the controller's GPS position. In the GPS snapshot is of course not only X and Y but also GPS altitude (Z).
If the H does not take this in account and the pilot and thus controller ascends after take off during flight (almost the same or higher then programmed RTH height), the H might smash into the ground (or other obstacles).
I am sure it won't, although I did not test this yet.

I come to this belief because I am quite sure the H will check and update positions several times during its RTH. I did test (by coincidence) moving from the point of activation of RTH. Tthe H landed near the position I moved to (about 45 mtrs east from position of switching RTH on).


:)


A
 
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#13
Watch from 2:00. You will see the H has dynamic RTH. It will follow the Wizard and land near the last known position. As far as the RTH altitude goes I think it is using the take off altitude.

 
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Steve Carr

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#15
Two observations.
1. There is a subtle difference in selecting Home and a triggered RTH from signal loss. On signal loss the H is simply going to go back to the last know position of the ST16. It hovers waiting to regain signal. Home is a type of Smart mode. If you move while in Home the H will follow. If you move while it's landing, it may very well tip over just as it would if you moved in a Smart mode landing.
2. I believe the accelerometers may play a roll in "Home" landing. I think they will sense the ground effect and slow the rate of descent at that moment. It will be an interesting experiment. (Without the camera)
 

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