3
$\begingroup$

Picture a standard quadcopter, with regular old propeller guards, which are generally just circles around the propellers. Now, take the propeller guards and stretch them so that they're cylinders surrounding the immediate cross-section of propeller blades, as well as some distance above/beneath them.

Now I am fairly certain that it would be able to go up/down. But would it be able to turn? I know it is a relatively vague question, but after thinking about it for some time, I really have no idea. I might just modify the propeller guards on my cheap little drone to see if this works.

$\endgroup$
2
  • 3
    $\begingroup$ Place to start reading: en.wikipedia.org/wiki/Ducted_fan $\endgroup$ Nov 28, 2018 at 21:49
  • 1
    $\begingroup$ Oh nice, I didn't know that was what they were called, thanks! I'm trying to make it such that the cylinders are longer than what a standard ducted fan looks like (it seems like they only protrude past the propeller a bit) but this is a good starting point. Thanks! $\endgroup$ Nov 28, 2018 at 21:52

4 Answers 4

5
$\begingroup$

Yes. It would be able to turn. Of your 4 propellers, 2 spin clockwise and 2 spin counterclockwise. The torques cancel out. To make it spin, you run the 2 clockwise propellers a little faster and the other 2 a little slower. Now the torques do not cancel out and the quadcopter spins. This does not change if you have a ducted fan versus a propeller

$\endgroup$
1
  • $\begingroup$ Yeah that's kind of what I was thinking, is that it is virtually the same system so it should work the same. The thing is my design requires "ducts" that are approximately 6 inches long so I'm not sure how efficiently it would be able to achieve static flight. I know ducted fans are less efficient when the vehicle is not in motion... Thanks though! $\endgroup$ Nov 28, 2018 at 23:59
0
$\begingroup$

Yes, it could fly. It would yaw and ascend and descend as usual, but the extra mass of the ducts would slow down how those maneuvers start and stop. (It would feel sluggish.) Ducts help when diameter cannot be large and efflux speed matters more than raw thrust. But thrust is what's needed for hovering by any kind of copter, quad or not, and thrust depends strongly on diameter.

On a quadcopter, ducts might help in a straight-line high speed drag race, but not for more general missions that need endurance or agility or payload.

$\endgroup$
0
$\begingroup$

Yes, such a craft would be controllable in all 6° of freedom. What you have essentially designed there is a quad copter powered by ducted fans as opposed to traditional propellers. The concept still works, regardless.

Quadcopters control yaw by means of reducing motor power to one set of transverse rotors and increasing power to the other set up. The upshot of which is the aircraft has the same amount of lift but an imbalance in net torque about the vertical axis, causing the craft to yaw. The craft you suggest could be control about its vertical axis using a similar system, or you could do so using an auxiliary ducted fan to create the imbalance in torque about the vertical axis.

$\endgroup$
-2
$\begingroup$

Yes, they'd essentially be thrust nozzles.

$\endgroup$
1
  • $\begingroup$ Can you give a bit more explanation about why that would be the case? On Stackexchange it's encouraged to explain your answer instead of one-liners :) $\endgroup$
    – ROIMaison
    Jan 16 at 9:31

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .