Static lift with independent motors, props & battery?

[Xtreme Drone Pilot]

I wonder if anyone explored the possibility of extending flight times/distances not by loading Mavic with additional batteries, but adding independent motors with props and separate battery? The goal is to effectively make Mavic lighter. Obviously, to achive this, the lift created by the additional props must be greater than the weight of these additional parts, plus some. Two props spinning in the opposite directions. Mounted on a long enough carbon fiber tubing running from left to right of the aircraft. Do you think this approach can extend Mavic's performance or traditonal battery mods are more efficient?

These additional motors don't need any control, just flip the switch to turn them on, and they just provide static lift until their battery dies. The advantages of this approach: you retain the battery % readout in the app so you always know when it's time to land; the voltage doesn't need to match Mavic's, whatever is needed by the extra motors, which gives more freedom in choosing batteries; unlimited possibilities in choosing motors, RPMs, props, etc.

 

[JetexJim]

That's a rather interesting idea...which makes me think of another variant. How about adding wings to to the Mavic?

A simple flat section with a few degrees of positive A of A to develop lift in forward flight. Potentially there's no need for tail surfaces to add stability the four props should maintain the correct attitude. I do wonder what the control system would make of it? Would the props unload as forward speed increased and aerodynamic lift was generated?

Hmmm?

 

[Xtreme Drone Pilot]

Wings should work as long as they generate more lift than they weigh, and don't interfere with the props' blast. Another area is simply reducing parasite drag by adding light foam or balsa flarings to arms and legs, they are currently square profiles and create a lot of drag! Also, a teardrop flaring to the tail.

 

[Xtreme Drone Pilot]

Continuing generating crazy ideas - how about a multistage drone? Like rockets. A large drone is a Stage I, with enough room in the middle for a smaller drone, Stage II, with yet smaller drone sitting on top, Stage III. As you fly this Babylonian pyramid of drones and the Stage I nears the depletion, you command the Stage II to takeoff. Finally, you launch the Stage III. The principle is the same as with rockets: you get rid of empty tanks as you go. Fractal drones, anyone?

 

[BigAl07]

Keep in mind that to use wings you'll need to maintain forward flight and in the correct direction all the time or you create a crap load of drag. The beauty of a MultiRotor is being able to stop on a dime and fly in any direction.

 

[sar104]

I wonder if anyone explored the possibility of extending flight times/distances not by loading Mavic with additional batteries, but adding independent motors with props and separate battery? The goal is to effectively make Mavic lighter. Obviously, to achive this, the lift created by the additional props must be greater than the weight of these additional parts, plus some. Two props spinning in the opposite directions. Mounted on a long enough carbon fiber tubing running from left to right of the aircraft. Do you think this approach can extend Mavic's performance or traditonal battery mods are more efficient?

These additional motors don't need any control, just flip the switch to turn them on, and they just provide static lift until their battery dies. The advantages of this approach: you retain the battery % readout in the app so you always know when it's time to land; the voltage doesn't need to match Mavic's, whatever is needed by the extra motors, which gives more freedom in choosing batteries; unlimited possibilities in choosing motors, RPMs, props, etc.

Given that additional motors plus a battery must weigh more than just an additional battery, it presumably has to be inferior in terms of stored energy per unit mass of aircraft. So why would you expect it to be the better solution for increasing range?

 

[Xtreme Drone Pilot]

Given that additional motors plus a battery must weigh more than just an additional battery, it presumably has to be inferior in terms of stored energy per unit mass of aircraft. So why would you expect it to be the better solution for increasing range?

Good point. But it's also not only about watt-hours per unit mass, but efficiency as well. (for example, an electric sailplane can have low Wh/kg, but can fly much farther due to efficient aerodynamics) Are there more efficient props and/or motors than Mavic's? Mavic's design is constrained by various requirements - flying characteristics, maneuverability, folding legs with props needed to fold, too, etc. etc. With the additional props, all you need is to provide efficient lift. Can, for example, ducted fans be used instead of traditional props? Maybe, they'll be more efficient? Maybe there are motors that don't have great "dynamic range" and acceleration, but are extremely efficient at certain constant RPM?

Another thing - additional props can be used not necessarily to create just lift, but thrust as well, by mounting them at some pitch angle. Many possibilities.

 

[sar104]

Good point. But it's also not only about watt-hours per unit mass, but efficiency as well. (for example, an electric sailplane can have low Wh/kg, but can fly much farther due to efficient aerodynamics) Are there more efficient props and/or motors than Mavic's? Mavic's design is constrained by various requirements - flying characteristics, maneuverability, folding legs with props needed to fold, too, etc. etc. With the additional props, all you need is to provide efficient lift. Can, for example, ducted fans be used instead of traditional props? Maybe, they'll be more efficient? Maybe there are motors that don't have great "dynamic range" and acceleration, but are extremely efficient at certain constant RPM?

Another thing - additional props can be used not necessarily to create just lift, but thrust as well, by mounting them at some pitch angle. Many possibilities.

Sure - if you include the possibility that there are more efficient motor/prop combinations than the Mavic uses then it could work. But in that case why would DJI not already be using them? That's basically becomes the same as asking if you can design a more efficient UAV.

 

[Xtreme Drone Pilot]

But in that case why would DJI not already be using them? That's basically becomes the same as asking if you can design a more efficient UAV.

Mavic's design is constrained by various requirements - flying characteristics, maneuverability, folding legs with props needed to fold, too, etc. etc. With the additional props, all you need is to provide efficient lift.

 

[sar104]

Mavic's design is constrained by various requirements - flying characteristics, maneuverability, folding legs with props needed to fold, too, etc. etc. With the additional props, all you need is to provide efficient lift.

That doesn't explain at all why it would require the use of less efficient motors.

 

[Xtreme Drone Pilot]

That doesn't explain at all why it would require the use of less efficient motors.

The same could have been said in pre-Platinum times. Then BOOM! - the new ESC and new props make Mavic more efficient by 10%. Somebody here installed non-folding, larger props - again, efficiency has improved. It's not just the motors, it's the whole system that matters, but even motors can be better than DJI's because they don't need to be similar to Mavic's in size and operational characteristics, they can be tailored to one specific task - spin at predefined constant RPM. I can imagine that bigger motors are more efficient than small ones. Also, cost efficiency of a mass-produced consumer product - there could be more advanced, and much more expensive motors that DJI chose not to use in Mavic to keep the price what it is.

 

[BigAl07]

I wonder how this new Thrust Line will affect the Flight Controller. Keep in mind it will control the motors (at least the factory ones) to maintain a certain angle of attack or level (depending on the requirement from stick inputs etc). Motors pushing the aircraft more forward might have a negative affect as the FC will try to maintain a certain attitude.

The factory FC is not going to play nice with these modifications... at least not without some deep tweaking.

 

[Xtreme Drone Pilot]

Besides general enthusiasm of tinkering with Mavic, Leaderboards, and measuring whose **** is the longest, there could be very practical uses for increased flight times. Take, for example, shooting a game from the air, for soccer you need uninterrupted 45 minutes of footage, plus some margin. AFAIK, there's no consumer drone capable of flying for an hour. Now, imagine the fractal drone in action: Mavic, being turned on and shooting footage, is sitting on top of a bigger drone capable of flying for 25-30 minutes (with 734g load). You fly the "mothership", when it's depleted, Mavic takes off from it as mothership starts landing and flies for another 25-30 minutes. Mission accomplished - 50 minutes of uninterrupted footage.

 

[sar104]

The same could have been said in pre-Platinum times. Then BOOM! - the new ESC and new props make Mavic more efficient by 10%. Somebody here installed non-folding, larger props - again, efficiency has improved. It's not just the motors, it's the whole system that matters, but even motors can be better than DJI's because they don't need to be similar to Mavic's in size and operational characteristics, they can be tailored to one specific task - spin at predefined constant RPM. I can imagine that bigger motors are more efficient than small ones. Also, cost efficiency of a mass-produced consumer product - there could be more advanced, and much more expensive motors that DJI chose not to use in Mavic to keep the price what it is.

Fair enough, especially if cost is not a constraint.

 

[Qoncussion]

Besides general enthusiasm of tinkering with Mavic, Leaderboards, and measuring whose **** is the longest, there could be very practical uses for increased flight times. Take, for example, shooting a game from the air, for soccer you need uninterrupted 45 minutes of footage, plus some margin. AFAIK, there's no consumer drone capable of flying for an hour. Now, imagine the fractal drone in action: Mavic, being turned on and shooting footage, is sitting on top of a bigger drone capable of flying for 25-30 minutes (with 734g load). You fly the "mothership", when it's depleted, Mavic takes off from it as mothership starts landing and flies for another 25-30 minutes. Mission accomplished - 50 minutes of uninterrupted footage.

Wasn't this the plot of Apollo 13?