What's up with the slow speed?

[BudWalker]

Actually, I thought I had it in sport mode, but I think I may have turned it off on the way out. To be honest, I don't remember for sure if I did ever have it on. I'm sure the data says whether I did or not. I think I was freaking out so much knowing it wasn't going to get home at that speed and planning a field landing location that I didn't think about sport mode.

But to the issue of temp, it is still strange that the speeds increased when I got closer to home. Maybe the bird warmed up, maybe the headwinds died down. I guess it's hard to tell. I thought I'd be pretty safe as long as I was around 32 degrees. I've flown in colder temps with no apparent impact on performance-based the wind may have been lower too...

The data shows it wasn't in Sport mode.

The speed increased in the last part of the flight because it was doing an RTH. Before the RTH the lower pitch limit is -16. During an RTH the pitch has a lower limit of -24 allowing it to go faster.

@james_mav the forward thrust is dependent only on the pitch if the AC is at a constant altitude. The motor speeds can and do vary depending on things like temp and humidity. If the AC is at a constant height then the downward thrust has to be constant. If the thrust/RPM changes due to temp then the RPM has to change to keep the downward thrust constant. I.e., downward thrust is not dependent on temp. Since forward thrust is dependent only on downward thrust (which is constant) and pitch then forward thrust is dependent only on pitch.

 

[james_mav]

Actually, I thought I had it in sport mode, but I think I may have turned it off on the way out. To be honest, I don't remember for sure if I did ever have it on. I'm sure the data says whether I did or not. I think I was freaking out so much knowing it wasn't going to get home at that speed and planning a field landing location that I didn't think about sport mode.

But to the issue of temp, it is still strange that the speeds increased when I got closer to home. Maybe the bird warmed up, maybe the headwinds died down. I guess it's hard to tell. I thought I'd be pretty safe as long as I was around 32 degrees. I've flown in colder temps with no apparent impact on performance-based the wind may have been lower too...

How does the bird fly n

The data shows it wasn't in Sport mode.

The speed increased in the last part of the flight because it was doing an RTH. Before the RTH the lower pitch limit is -16. During an RTH the pitch has a lower limit of -24 allowing it to go faster.

@james_mav the forward thrust is dependent only on the pitch if the AC is at a constant altitude. The motor speeds can and do vary depending on things like temp and humidity. If the AC is at a constant height then the downward thrust has to be constant. If the thrust/RPM changes due to temp then the RPM has to change to keep the downward thrust constant. I.e., downward thrust is not dependent on temp. Since forward thrust is dependent only on downward thrust (which is constant) and pitch then forward thrust is dependent only on pitch.

Thanks for the explanation. Some guy was posting that he was flying in -40 degees so it doesn't look like temp plays a big factor in most instances.