RTH and Optimal Speed

[Paul Schulze]

What speeds are Phantom pilots recording on RTH?

 

[stones]

22 mph

 

[Meta4]

What speeds are Phantom pilots recording on RTH?

The Phantom's RTH speed is well below top speed and if you find yourself in a low battery or headwind RTH situation, you will do better to switch of object avoidance and push the right stick forward to get more speed.
The best speed for distance is just a fraction below top speed.
Leaving your Phantom out there putting along slowly is not the way to get home when every milliamp-hour counts.

 

[Brockrock]

I have read multiple posts here in the past by some of the long distance, adrenaline enthusiast that approximately 30 MPH is the most efficient overall speed for the P4 regarding their purposes. I enjoy taking the copter out to some of the small atoll islands offshore to do a bit a seal watching from time to time, and I have found this to be a good speed to get the copter out and back while giving me the most time on site to look around.

 

[Paul Schulze]

There has been much discussion about the RTH speed for best battery use. The conclusion from PhantomPilots is faster rather than slower. Here is a link to a study of several popular models which shows a different result (article has been mentioned in another thread):

Airdata UAV - Flight Data Analysis for Drones
From their study:

"Interestingly, the Martice 600 is the only aircraft that is working significantly harder while hovering than while moving (12% less efficient). This may be due to the aerodynamics of the aircraft as it expends energy to stay in one place."

How does this fit with what others have been saying? Confused???

 

[Meta4]

There has been much discussion about the RTH speed for best battery use. The conclusion from PhantomPilots is faster rather than slower. Here is a link to a study of several popular models which shows a different result (article has been mentioned in another thread):
How does this fit with what others have been saying? Confused???

The Airdata blog post only looks at Minutes per Battery which is fine if you just want to hover nearby.
But it tells you nothing about distance and most pilots are a lot more concerned about distance rather than time..
You get great flight time at 5 mph and less at 35 mph but it takes you a lot further.
And if you are running low on battery coming home, flying at 5 mph won't cover the distance in time.

 

[blackcrusader]

I've had 50 mph plus but that was on return from a flight into a headwind. Had a nice quick return.
Phantom 3 Standard

 

[Duchunter]

Seems like the faster you go the more efficient it would be. At least for a p3\p4 type airframe. Its more or less a lifting body so increased speed means increased lift.

 

[Crack The Sky]

Seems like the faster you go the more efficient it would be. At least for a p3\p4 type airframe. Its more or less a lifting body so increased speed means increased lift.

Drag increases 4 to1 over lift. Basic physics.

 

[Meta4]

Seems like the faster you go the more efficient it would be. At least for a p3\p4 type airframe. Its more or less a lifting body so increased speed means increased lift.

Drag increases 4 to1 over lift. Basic physics.

It all depends on how you define efficiency.
The Airdata post looked at time per battery.
If you look at miles per battery, hovering or moving slowly is the least efficient because the Phantom uses most of its energy just to fight gravity.
The Phantom doesn't develop much lift from airflow over the body like a plane's wing does.
If you are interested in what speed is most efficient, this post is for you:
Best fuel efficiency tests

 

[Crack The Sky]

It all depends on how you define efficiency.
The Airdata post looked at time per battery.
If you look at miles per battery, hovering or moving slowly is the least efficient because the Phantom uses most of its energy just to fight gravity.
The Phantom doesn't develop much lift from airflow over the body like a plane's wing does.
If you are interested in what speed is most efficient, this post is for you:
Best fuel efficiency tests

You are correct. Not being a true lifting body, (having a lift producing wing), the Phantom, at slow speeds uses a tremendous amount of energy just remaining aloft. At some higher forward speed, it is fighting enough drag that it is wasting energy. Somewhere in the middle is the "sweet spot"; the maximum distance able to be traveled, for the least amount of energy use possible, to maintain altitude.

 

[Crack The Sky]

It all depends on how you define efficiency.
The Airdata post looked at time per battery.
If you look at miles per battery, hovering or moving slowly is the least efficient because the Phantom uses most of its energy just to fight gravity.
The Phantom doesn't develop much lift from airflow over the body like a plane's wing does.
If you are interested in what speed is most efficient, this post is for you:
Best fuel efficiency tests

Thank you so much for the link to "Best Fuel Efficiency Tests". So, 13-14 m/s is the "sweet spot"for energy consumption. 29-31 mph.

 

[CharlieU]

I've had 50 mph plus but that was on return from a flight into a headwind. Had a nice quick return.
Phantom 3 Standard

View attachment 82173

This is an interesting discussion. My top speed was 59.24 mph returning from headwind.

My maximum Flight Time 22m 15s. Take off battery 100% Landing battery 17%. Speed was set at 18 mph. Flight was supposed to be 18 mins. 18 mins into the flight the P4 was still 2300 ft. from home I increased speed to 42 mph and made it home over 4 minutes late.