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RTH speed in P or S mode
- Thread starter AlanTheBeast
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The speeds you have quoted seem to be the max for the applicable modes- you won't get anywhere near that in RTH. For the earlier models RTH was 10ms (36km/hr)- the P4P may be quicker, to the extent it is it won't be close to the max available in the relavent flight mode.
RTH will work in ATTI mode providing enough satellites are available for GPS positioning and the compass if functioning properly.
RTH will work in ATTI mode providing enough satellites are available for GPS positioning and the compass if functioning properly.
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Just don't ever forget returning in headwinds that are strong. Because that speed is also about cut in half. Heard over 100 times of people flying out with a tailwind really far and not making it back because they didn't take into account the returning headwind speeds. I know this isn't answering your question but just a friendly reminder to not forget.
It doesn't normally use full power, normally 10m/s on the P4P too. I think part of the reasoning for this is to use a speed that is more battery efficient, and a speed that collision avoidance works on. Although it does look like it tries to do 10m/s ground speed, not airspeed, so in high headwinds may use near full power to achieve that. You can use the stick to speed things up, but as others have said, a headwind on RTH can make for dicey returns.
It is well proven that 10ms is somewhere around 40% below the airspeed that provides greatest flight distance on the phantom 3 series and we have no reason to suspect the P4 might be significantly different.
22mph is just shy of 10ms. I understand the P4 is the same however only going by what I have read, I haven't tested it.
Meta4
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10 m/s is very battery inefficient and you'll go much further at 13-14 m/s.
DJI set 10 m/s for RTH long before they had OA on Phantoms.
The reasoning is a total mystery.
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Flying outbound into a headwind is one of my top mantras. Or if unavoidable, then to curtail both range and loiter time and come back in S-mode.
From the replies I'm gobsmacked that DJI haven't used the most range efficient speeds. Or even higher if they consider a headwind (more power needed than in still air to make a given groundspeed).
That's really interesting. I didn't state that as fact, ("I think") as it was the most likely reason. If they don't use the most battery efficient speed to RTH, and still have collision avoidance working, I really don't understand why they would do anything else. It just makes sense to give yourself the most range when doing RTH. Does anyone have a link to a chart on this information? I'd like to understand it.
Meta4
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Here's the best thread on speed/distance efficiency: Best fuel efficiency tests
Wow. I sounds like 10m/s was randomly chosen as it's a round number. I am totally surprised they would not use a more efficient speed. Even more so when returning to home in a headwind. That warrants going very fast. In fact, there is enough data onboard to even compensate for wind measuring the highest efficiency over the amount of distance covered. I'm surprised they don't use it as RTH battery use is especially important when triggered by low battery.
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