The wings should have their center of drag in line with the center of mass of the craft to avoid introducing the pitch moment that caused the oscillations. This is tough because the wings would have to be mounted even farther outboard to avoid colliding with the rotors. If the front/rear motor pairs were moved more frontward/rearward instead, clearance for the wing could be introduced without elongating it and the available pitch moment from the motors pair would be increased, allowing it to more effectively counteract any pitch-wise disturbance.
that plus these wings are dead they have no control surfaces to combat aerodynamic forces like you would have in any real or model rc aircraft, adding this would likely fix it. ditch the homemade wing and get one for a rc plane that has all the control surfaces built in and intergrate it into the drone so that its software begins operating them to keep it in line with its stabilization programing. Also there's another way to improve efficiency , by changing out the rotors for the torodial design they not only improve flight BUT are near whisper quiet making the drone hardly noticable
Yes. It should have neutral static stability so the rotors have authority. I.e. the aero body must be orientation agnostic with respect to the relative wind and generate no torques about the cg. I don't know how close one can come to this in reality. None of these designs ever come close though because they don't even try.
The other thing to consider is the fact that, not only is the wing causing a pitch moment due to induced forces, the center of mass is now shifted higher if not above the motors creating an unstable system. Even just adding a ballast below the quad could theoretically make the motor control play a little nicer.
I had a thought in a slightly different direction. How about 2 smaller wings, one in front of the front motors and staggered vertically but forward and out of the prop wash path, and the rear staggered slightly below the vertical rotation axis of the rear motors, behind the rear motors, again out of the wash path. So front and rear wings. This would of course require a landing gear to prevent awkward takeoff. But with the same pivoting wing with rotation stops would certainly have fair upward lift without the interference with prop flow paths. It should also equalize the load decrease across the motors..
The wing should be placed in the same way as it would be on an airplane, at the center of mass or further back. to me it looks like the quad is fighting against the instability of its back heavy nature. "A front heavy plane flies badly, a back heavy plane flies once" - Some kerbal space program enjoyer
For years we have been privately testing this exact concept with over 300 test flights on DJI and other drones and we filed a patent in 2019. All the issues mentioned in the comments have been resolved and patented in US Patent US20210107637A1 "Universally attachable hinged wing and vlos aid for multirotor drones". We are scheduled for the release of our product line soon.
With a properly tuned flight controler taking the wing into account, I think your preliminary data shows the wing it might have a significant efficiency gain in forward flight. I think for certain mission profiles you're onto something. As always great video Thanks
At Warwick university I saw a drone/fixed wing hybrid that had a stationary delta wing which was vertical when on the ground and then the drone completely turned horizontal during free flight thus turning into a fixed wing plane with a rotor above and below each side of the wing. I imagine this required custom software to calculate the best angle of attack for different speeds.
The RC aircraft X-Vert seems to be what you are describing, but with only a pair of motor. It uses pre-programmed maneuvers to transition to fixed wing and back again, while also changing the flight controls to be the standard for each.
Tailsitters are efficient for long range, although as a camera drone the body interferes with the downward field of view at low speeds or hovering, and cannot fly sideways at higher speeds. The concept in this video has been patented in US patent US20210107637A1 "Universally attachable hinged wing and vlos aid for multirotor drones" and we are scheduled for the release of our product line soon.
Move the wings down to the center of mass of the drone, to avoid having it add a speed-pitch feedback making it unstable. Control the wing AoA with a servo so that it's always correctly oriented relative the direction of travel through the air. Perhaps add a few degrees of dihedral to the wings to get a bit more stability. Use an airfoil section optimized for the very low speeds seen here, something appropriate for maybe 1-3 million Re.
The "dihedral=stability" equation is not so clear cut. the way dihedral works is by rolling the plane in the direction opposite sideslip at positive AOA, but with this arrangement that just adds more complexity for the control system to fight against.
All the issues mentioned have been resolved and patented in US Patent US20210107637A1 "Universally attachable hinged wing and vlos aid for multirotor drones". We are scheduled for the release of our product line soon.
Maybe have the rod going through the wings be closer to the center of mass of the wing so it's easier to reach the edge case. This way, the drone uses less energy to keep the wing up
agreed. i have been watching his videos for years and its always fascinating yet informative along with his uniquely deep voice being chill to listen to lol
rctestflight your research is inspiring and see where you are going. Based on your RPM data showing distinct differences between 4 rotors perhaps prudent to try positioning 4 separate wings behind the thrustline (beneath) of each rotor. So as each rotor thrust will behave independently and observe any change in stall threads attached on low pressure surface of each wing in full throttle forward cruise. In turn cumulative lift may show where lift disparities exist. Good job of messing around so much with this, excellent!
How about the sort of angle-of-attack control tail/elevator thing you used on your rigid wing sailboat? I think that would be a lot smoother than the hard stop on the wing angle.
Or an tuned progressive elastic resistance to the AOA? Like 3 different surgical tubing lengths in parallel, that way the AOA would be a function of the airspeed. You could still have a hard stop and the period of the oscillations may be longer as well. The tuning might be tricky, but maybe with force meter measurements on a hard stop for several AOA/airspeed combos you could tune the elastic dampening. Great video!
No way bud. The wing should be centered on the CG. Any aerodynamic stability, positive or negative, is going to fight the pid controllers. Aerodynamic stall is desirable in some cases and a normal part of the maneuvering flight regime. An AoA sensor should feed the FC to inform cruise efficiency. Get all these nasty aerodynamic flipperon things out of here. This is a quadcopter!
I'd really like to see this experiment repeated with the anomalous motor issue fixed. Like you said having one motor completely idled is really going to mess up the quads ability to stabilize itself and it might be a lot better without that problem present.
A tail-sitter craft with four props in a quadcopter orientation, can easily make the transition to forward flight. The camera gimbal can be held on a swinging (pitch) axis. Keeping the entire camera assembly below the craft as it transitions back and forth between forward flight.
The way you mounted the wing high above the quad puts the center of lift ahead of the CG when the quad pitches to translate forward. Thats almost certainly the main cause of your pitch instability in fast flight. The front motors are decreasing in speed to the point of idling because pitch moment from the forward positioned wing is so large it's taking all the load off them.
What if you put the wing fixed perpendicular to the rotors and in flight go full throttle and angle the quadcopter 90° forward and use it as a conventional aircraft. But then basically you've converted it into a VTOL
I love the idea and it apparently works a bit, extend the wings out beyond the rotors and mount it to the bottom of the frame of the unit. maybe make the size of the wings about 1/4 of the size that you have on there now. just a thought from my head.
For a future video, try mounting the wing below the rotors, this may seem more unstable but it's highlighted to be just as viable as above aerodynamically by the drone pendulum fallacy. Having the wings below will allow them to rotate without the consequence of hitting the rotors, potentially allowing you to bring the CoL closer to the CoG (although, I'm not sure whether the downwash from the rotors will impact this).
Great idea but I think it would need a rewrite to the controller. Combining what Zipline does with being able to take off and land anywhere would be great
You essentially made a canard aircraft without the rest of the air frame and gave it some alternative form of P thrust. Thinking about how it all interacts is making my head spin, so keep going and make more iterations!
The drone is missing some kind of more effective pitch control like in standard airplanes, i think this is causing the oscillations. Also fins below the rotors maybe would prevent the rotation of the airflow, which could boost efficieny as well
I agree. I think the flight controller program would need to be designed for this hybrid design and also include servo control for wing pitch, and then it should be able to effectively counter the instability.
I'd love to see you push this idea a bit further. an idea I had would be to have 2 wings across with 2 rotors set into each wing. That might give you more stability. in any case, love the vids and cant wait for the next one!
Late to the party, but I think the performance would be better with the wing mounted just below the props instead of above them. It'll also be a more compact overall package.
the down wash of the props would keep pushing the wing down aswell as messing with the airflow over the wing so idk if it would be better, would like to see it tested still
Very interesting, even to a non mechanical/non engineer amateur drone enthusiast like me. I subscribed after watching your first Dyson vacuum engine powered airplane flight . The more I watch, the more I'm hooked on watching your UA-cam videos. You're a very smart young whipper snapper. And as I watch this video, it makes me proud to be from the Pacific Northwest. ( grew up in Bellevue) but live in downtown Seattle now. Keep up the good work!
Here's my silly idea: Instead of large solid foam wings, use small spools of fabric and pairs of linear tracks to create the airfoil. Winches made with continuous servos will be used to extend the fabric, while the spool will be tensioned back by coil springs. This could provide more adjustments besides rotation, as there's total control over the airfoil's surface area. For example, to retract it partially or entirely when hovering or in turbulence. Wait a minute, did I just reinvent sails and repurpose it as a motorized kite...? 🤔
Check out the British designed Fairey Rotodyne from the late 1950s. A single rotor was used for take off and landing and which was then then put into auto-rotation during level flight. Lift also came from 2 short span conventional wings where the propeller engines were mounted. The system worked well but the biggest con was the noise made by the rotor tip jets on take of and landing. Not a good point as the aircraft was intended to be operated from city centres. There was a hush kit in design when the project was cancelled but by then it was too late to get any more government funding :(
Finally! I've been periodical searching online to see someone do this... I've been thinking of it as an attachment to dji drones that already have long flight times!
Whenever I move to Washington in the future I hope I get to see your inventions getting tested around Seattle. How fun would that be to see some device and think "oh that's just rctestflight"
I actually made something a lot like this a few years ago, but for a 4' quad style base, and rather than 1 wing in the middle, I had 2 wings front and back. They were automatically put level with 1 servo that was linked to both of them. It kinda worked for the lift aspect but the control algorithm had a ton of trouble with it. I never ended up getting a chance to fix that though.
Nice work. Look at the scorpion/stargazer freewing UAV and design your wing the same way. Use a pitch neutral airfoil (flying wing airfoil) and you can remove the stops and have the wing self align regardless of airspeed. Aurora flight sciences also had a vtol with this idea many years ago
Agreed with all the comments about the CG vs center of drag, but something else that might be worth trying is no stop on the AoA and then some kind of tail boom and stabilizer attached to the wing in the same way those drone sailboats get the perfect AoA on their sail
I like the approach as I've made similar concepts some time ago. I used servo-like stabilized AoA of the wing to maintain constant angle regardless copter pitch and current sensor to get real power consumption. I notified significant gain in efficiency, however I dealt a lot on control algorithms as copter's autopilots does not like a wing to be attached and provide lift. It is bit misleading to autopilot, you increase the forward speed and you generate lift so it needs to decrease the thrust having less authority to control pitch, roll and yaw.
Thanks for another great video! I was wondering, have you ever thought about giving a drone a body that acts as a lifting body? Or any other shape that generates lift?
Have you considered a "freewing" system? Essentially, build the wing as a flying plank with a reflexed airfoil, or with a trim tab to adjust the reflex for different speeds, and then set the pivot so that it matches the flying plank's CG. With this setup the wing should hunt for the ideal angle of attack in the relative wind without needing a stop.
Wow, this idea looks great, but I would suggest to mount the wing further rearwards and with a fixed pitch angle because when the center of lift of the wing is behind the CG the wing actually provides positive pitch stability so it wont get into those oscillations. Also would negative angle of attack not cause the drone to crash because it would limit the maximum forward pitch of the quad. I really would like another video of this concept with some design improvements.
I was thinking the same thing about wing location. When the drone tilts forward, the wings move forward causing lift in the front so the drone tilts back, shifting lift to the back etc etc. I have no expertise though so was looking for a comment that was similar.
I am currently completing my senior design and my project is a fixed wing (piper cub style) with vertical take-off and landing capability and a forward pulling traditional style motor. This is interesting because it's such a different approach from the previously mentioned Warwick university example. I would see this design being helpful at very slow speed but testing this to a slow flying fixed wing VTOL would be interesting to see what design is more efficient. could be useful for package delivery applications... maybe... as you mentioned high wind would be extremely detrimental to this design.
I don't want to give any suggestions but...The whole wing looks oversized. Try making it less wide (less wingspan) and possibly thinner with slightly reduced area and even 6 degrees dihedral. I believe it will help especially at 12+ m/s. I hope you can try again. Good Luck
Also, the wing will be doing some crazy stuff to the airflow into the top and bottom pairs of rotors during the different flight regimes, potentially creating a negative feedback loop and reducing control authority - ie accelerating the air into the bottom rotors reducing their net thrust and slowing the air into the top rotors increasing their net thrust
A wing mounted on top, like Chocolate Rocket commented, added a pitch moment because the drag force is acting a distance away from the center of mass. On top of that, the center of mass has been shifted upwards, creating even more instability. To counteract both of these points, you could try sizing down the airfoils and adding equivalent airfoils to both the top and the bottom of the quad. You technically don't know exactly where your center of mass is unless you're able to model all of the parts in CAD and use an assembly to let the computer figure it out for you, but you can use intuition to approximate where it is. Even if the top and bottom airfoil aren't the same distance from the center of mass, the resultant forces and moments will bring the system much closer to stability.
In the hover (or "drone") orientation, having the wing above the center of mass increases stability. (In terms of forwards/backwards speed: going forward increases drag on the wing, which is above the center of mass, so it pitches you back, which decreases drag, and so on.) If your drone pitches forwards into "plane-like" orientation and tries to go fast, it is putting the wing in front of its center of mass - A very famous thing that is making a craft unstable. There's 2 possible solutions: *Either* move the pivot rod to *below the rotors* to get it to the same height as the center of mass or below it. In this case you'll loose the stabilization in drone-mode. *Or* move the pivot rod further *towards the rear* of the drone. That will increase the stability in the airplane-like orientation. You can get away with keeping the wing above the propellers if your drone never pitches more than 35° or so down (which may _not_ be true, since I expect optimal efficiency gains close to 90° down pitch).
Cool idea. We went through this with the UAVforge spy drone project. Fixed wing VTOL planes do exist. Motors are mounted on the wings, but the whole wing can rotate so it effectively becomes a bi-copter.
Two ideas that occurred to me watching this: 1.) Add four wings to a quadcopter where the propeller arms form the main spars. I think that with the right control algorithm you could directly control angle of attack (not just with ailerons/elevators), but could also purposely induce side slip/lateral motion without rolling or turning, which a conventional aircraft cannot really do. 2.) Create an aircraft with no control surfaces, that controls its orientation solely through rotating internal weights and conservation of angular momentum.
So, in my experience, drones often have to run their rear motors faster than their front motors when moving quickly because the faster they go the higher the righting moment in pitch due to aerodynamic forces. I don't know if that's universal, though. Maybe it depends on how your central body is shaped? But, as others have said, you are also getting a pitching moment from having the wings so high above the center of mass. Putting that all together, I'm impressed that it worked as well as it did.
I’ve been designing and flying RC planes for 40+ years. In order for this to have any chance of working, you need to do two things. First, get the center of mass (CG) of the drone about 35% back from the front of the wing. Second, use an accelerometer, servo, and small microcontroller that can adjust the wing’s angle of attack so regardless of the flight angle of the drone, you keep the wing’s angle of attack to the wind in the 0 to +3° range, depending on the airfoil. Otherwise, the wing just acts like a big sail.
Aeroespace engineering student here, those oscilations are caused by positive arch wings by definition having a positive pitch moment alpha derivative, thats why flying wings need to be delta shaped or atleast have some negative tip angle of atack so that the total pitching moment derivative is negative, crating a self stabilized flight
Oh, also, just a fun note, but the actual oscilations are caused by the angle of attack becoming so steep that the wing stalls and the nose falls back down and the cycle repeats again
Could you use glider wings pivoting at the center of mass of the rotorcraft? You might be able to make those clearances work with the downside of being much wider.
An idea I recently considered: Attaching helium filled balloons to a quadcopter to offset some of its weight and therefore reducing energy consumption for hovering. I have not gotten around to doing even some cursory math on how big these balloons would have to be to make any noticeable difference and so that the (volume of gas)/(weight of mount + balloon) works out to be at all productive, but I think it could be a fun thing to try. The attachment of the balloons would certainly have to be static, so that it is not a quadcopter swinging around helplessly on a cord below a balloon, and the large surface of a balloon could create some real problems with wind. Idk, maybe one could design a funky looking quadcopter airship.
i think this is the application of tilt rotor aircraft. Being able to rotate the propellers forward allows the payload to stay in the same orientation while flying vertically and laterally.
Love it!!! one thing we didn't see was the wind direction, which could have explained the no thrust motor. and as other said, think the wings need to be closer to the center of mass, or maybe double them up as a large biplane?
Awesome idea to improve drone efficiency! I think the main cause of instability is the aerodynamic pitch instability induced by the airfoil. As soon as the wing starts flying. Every normal aircraft needs to adress this problem. Usualy its done by choosing diferent agles of incident between main wing and tail wing. The simplest way to fix this on your drone would be probably by using a stable airfoil like its used for flying planks. No need for a tail anymore.
Build one you can fly yourself around, everyone seems to place the pilot at or above the rotors, on a hard landing the pilot could be thrown down onto the rotors, and if the pilot is at rotor level a blade could snap and impale them, i'd like build my own with a fuel engine with two counter rotating props for the main lift, and four battery rotors for control. really enjoy your videos
The best example to take inspiration from for fixed wing efficiency & Quadcopter type VTOL (vertical take-off & landing ) performance will be a US made military aircraft called V-22 osprey . Hope some makes a RC drone based on it
Could a rear stabiliser be attached to the wing spar, reaching back between the rear rotors I wonder? So that it could pivot with the wings, but not be affected by the rear rotor wash. Almost like a quad/ultralight? Hmm.
I wonder what would happen if you added control surfaces to the wing for pitch control, and then added some sort of basic gyro stabilizer to control them. Independant of the flight controller on the quadcopter. Or maybe some sort of mechanism to control angle of attack in the same way
That's what I was thinking. Stage 1 add control surfaces which try to keep the wing AOA independent of drone AOA. Then stage 2 could be adding roll control assistance stabilization.
Great video, thanks a lot for this story, and for the already thorough analysis. We have similar ideas, that we should try in the next months, I'm looking forward to being able to report on our own progress.
Drone programmer here, the wing seems way too complex system for the PID to handle, especially may be the following: at speed X, the wing is pushing you UP, and if this is more than the drone can compensate lowering motor speed, it goes crazy. Also sudden loss of lift (stalling) is something PID cannot handle. Also, where is your center of lift? PID are a more a final touch, the more the drone guidance know about its physic, the better result you have Edit: if you would ask me how to start programming this, i think that first think you need to control electronically the pitch, or you cannot handle dynamic speed, you have one speed that is your most efficient and you cant exceed without keeping altitude requirements. I would create a test in something like xplane, as it does actually simulate propeller physics and other aero property; and create a table to what best pitch give the best result. It is simply too many hour to properly create an optimizer , the lookup table is the best. Also while the wing are engaged, you probably want to use less motor and more wing control, as the wing itself will stabilize pitch roll and yaw.
Feedback: one way to avoid negative pitch moment at high speeds is mount a fixed-pitch wing forward of CG (1-3 degrees positive AoA); a slow climb is way better than a high speed crater Next experiment: Place the wing below the rotors & fix the pitch (to eliminate oscillations). Test your theory regarding rotor wash. You might also want to experiment on wing placement (test forward of CG & aft of CG).
One key difference with the flight testing in this video is the all-up-weight of the drone was not the same with and without the wing. When flying without the wing an equivalent amount of weight should have been carried by the drone. Expect we'll see much better efficiency when the challengers have same AUW. (12:28) To avoid sketchy flight maneuvers, it would help to add a radius between waypoint legs. Those 180º turns are just asking for craziness. Not having a fixed wing (non-pivoting) would cause he centre of lift to vary as pitch angle varies. Location of centre of lift vs. centre of mass can effect stability. Overall a fascinating experiment Daniel. Like how you totally skipped any testing with a robust 5-inch, or 7-inch freestyle quadcopter and went straight to flight testing on a 13-inch monster-copter.
Separate the wings by more so they are outside the area of the rotors . Also id lose the pitching of them. Not quite fixed but way less movent away from facing the way a wing should.... You know better than me AND know the quad but that still seems like what it wants..... Keep them coming dude! I love your videos. They're like mental chewimg gum.... 😎 Also.... It might be worth at least trying having the wing UNDER the rotors.... You never know it might add the low pressure needed above the wing if its at a helpful angle or something. In any case i think getting the wimgs outside of the rotor footprint would be a very good thing......
how does this compare to tilt rotors? this actually has some really interesting utility for giving extra range to infiltration and reconnaissance drones
The wings should have their center of drag in line with the center of mass of the craft to avoid introducing the pitch moment that caused the oscillations. This is tough because the wings would have to be mounted even farther outboard to avoid colliding with the rotors. If the front/rear motor pairs were moved more frontward/rearward instead, clearance for the wing could be introduced without elongating it and the available pitch moment from the motors pair would be increased, allowing it to more effectively counteract any pitch-wise disturbance.
that plus these wings are dead they have no control surfaces to combat aerodynamic forces like you would have in any real or model rc aircraft, adding this would likely fix it. ditch the homemade wing and get one for a rc plane that has all the control surfaces built in and intergrate it into the drone so that its software begins operating them to keep it in line with its stabilization programing. Also there's another way to improve efficiency , by changing out the rotors for the torodial design they not only improve flight BUT are near whisper quiet making the drone hardly noticable
Yes. It should have neutral static stability so the rotors have authority. I.e. the aero body must be orientation agnostic with respect to the relative wind and generate no torques about the cg. I don't know how close one can come to this in reality. None of these designs ever come close though because they don't even try.
You can technically solve this by just adding an equivalent system to the other side. Could try using smaller wings mounted top and bottom.
The other thing to consider is the fact that, not only is the wing causing a pitch moment due to induced forces, the center of mass is now shifted higher if not above the motors creating an unstable system. Even just adding a ballast below the quad could theoretically make the motor control play a little nicer.
I had a thought in a slightly different direction. How about 2 smaller wings, one in front of the front motors and staggered vertically but forward and out of the prop wash path, and the rear staggered slightly below the vertical rotation axis of the rear motors, behind the rear motors, again out of the wash path. So front and rear wings. This would of course require a landing gear to prevent awkward takeoff. But with the same pivoting wing with rotation stops would certainly have fair upward lift without the interference with prop flow paths. It should also equalize the load decrease across the motors..
The wing should be placed in the same way as it would be on an airplane, at the center of mass or further back.
to me it looks like the quad is fighting against the instability of its back heavy nature.
"A front heavy plane flies badly, a back heavy plane flies once"
- Some kerbal space program enjoyer
A front heavy plane flies badly unless it is flying very fast.
this is the kind development and testing I want to see more of.
mee too !!
For years we have been privately testing this exact concept with over 300 test flights on DJI and other drones and we filed a patent in 2019. All the issues mentioned in the comments have been resolved and patented in US Patent US20210107637A1 "Universally attachable hinged wing and vlos aid for multirotor drones". We are scheduled for the release of our product line soon.
100% 👍
@@dronedevices Will be watching for this release! ;)
@@AirtimeAerial Thank you for your interest!
With a properly tuned flight controler taking the wing into account, I think your preliminary data shows the wing it might have a significant efficiency gain in forward flight. I think for certain mission profiles you're onto something. As always great video Thanks
At Warwick university I saw a drone/fixed wing hybrid that had a stationary delta wing which was vertical when on the ground and then the drone completely turned horizontal during free flight thus turning into a fixed wing plane with a rotor above and below each side of the wing. I imagine this required custom software to calculate the best angle of attack for different speeds.
You could always abruptly transition to forward flight mode, stall, and recover
The RC aircraft X-Vert seems to be what you are describing, but with only a pair of motor. It uses pre-programmed maneuvers to transition to fixed wing and back again, while also changing the flight controls to be the standard for each.
Yep, they're known as Tailsitters.
Though there's not usually any custom programming required, Arduplane supports the configuration out of the box.
Tailsitters are efficient for long range, although as a camera drone the body interferes with the downward field of view at low speeds or hovering, and cannot fly sideways at higher speeds. The concept in this video has been patented in US patent US20210107637A1 "Universally attachable hinged wing and vlos aid for multirotor drones" and we are scheduled for the release of our product line soon.
PteroDynamics has released the video of their transwing drone the uses fold of wings with the props on to go from vertical to horizontal flight.
Move the wings down to the center of mass of the drone, to avoid having it add a speed-pitch feedback making it unstable. Control the wing AoA with a servo so that it's always correctly oriented relative the direction of travel through the air. Perhaps add a few degrees of dihedral to the wings to get a bit more stability. Use an airfoil section optimized for the very low speeds seen here, something appropriate for maybe 1-3 million Re.
The "dihedral=stability" equation is not so clear cut. the way dihedral works is by rolling the plane in the direction opposite sideslip at positive AOA, but with this arrangement that just adds more complexity for the control system to fight against.
it will the the blades
@@hazza2247 my in goes with pitch up free
@@brycering5989 what?
All the issues mentioned have been resolved and patented in US Patent US20210107637A1 "Universally attachable hinged wing and vlos aid for multirotor drones". We are scheduled for the release of our product line soon.
How do I increase the range of a helicopter
Google: Make a tiltrotor
Bing: Duct tape a wing on it lmfao
Maybe have the rod going through the wings be closer to the center of mass of the wing so it's easier to reach the edge case. This way, the drone uses less energy to keep the wing up
Wow this is so much fun and relaxing to watch these types of videos from you.
agreed. i have been watching his videos for years and its always fascinating yet informative along with his uniquely deep voice being chill to listen to lol
rctestflight your research is inspiring and see where you are going. Based on your RPM data showing distinct differences between 4 rotors perhaps prudent to try positioning 4 separate wings behind the thrustline (beneath) of each rotor. So as each rotor thrust will behave independently and observe any change in stall threads attached on low pressure surface of each wing in full throttle forward cruise. In turn cumulative lift may show where lift disparities exist. Good job of messing around so much with this, excellent!
There are still possibilities. I like that you illustrate the challenges and lessons learned. Great job!
man i love this channel. cant wait for the PeterStripol colab
How about the sort of angle-of-attack control tail/elevator thing you used on your rigid wing sailboat? I think that would be a lot smoother than the hard stop on the wing angle.
Or an tuned progressive elastic resistance to the AOA? Like 3 different surgical tubing lengths in parallel, that way the AOA would be a function of the airspeed. You could still have a hard stop and the period of the oscillations may be longer as well. The tuning might be tricky, but maybe with force meter measurements on a hard stop for several AOA/airspeed combos you could tune the elastic dampening. Great video!
No way bud. The wing should be centered on the CG. Any aerodynamic stability, positive or negative, is going to fight the pid controllers. Aerodynamic stall is desirable in some cases and a normal part of the maneuvering flight regime. An AoA sensor should feed the FC to inform cruise efficiency. Get all these nasty aerodynamic flipperon things out of here. This is a quadcopter!
I'd really like to see this experiment repeated with the anomalous motor issue fixed. Like you said having one motor completely idled is really going to mess up the quads ability to stabilize itself and it might be a lot better without that problem present.
Flight controller: “u wot m8”
Don't think a motor was actually idle, just the motors and telemetry were not calibrated.
@@AerialWaviator he said it was idled and it looked idled.
A tail-sitter craft with four props in a quadcopter orientation, can easily make the transition to forward flight. The camera gimbal can be held on a swinging (pitch) axis. Keeping the entire camera assembly below the craft as it transitions back and forth between forward flight.
The way you mounted the wing high above the quad puts the center of lift ahead of the CG when the quad pitches to translate forward. Thats almost certainly the main cause of your pitch instability in fast flight. The front motors are decreasing in speed to the point of idling because pitch moment from the forward positioned wing is so large it's taking all the load off them.
LOL why are there Hot Dogs on that Little VTOL?
Probably for stability. Hot dogs are great vibration dampeners. Some real science shit
What if you put the wing fixed perpendicular to the rotors and in flight go full throttle and angle the quadcopter 90° forward and use it as a conventional aircraft. But then basically you've converted it into a VTOL
The high levels of Sketch is one of the main reasons I watch ths channel.
I love the idea and it apparently works a bit, extend the wings out beyond the rotors and mount it to the bottom of the frame of the unit. maybe make the size of the wings about 1/4 of the size that you have on there now. just a thought from my head.
Having the centre of lift below the centre of mass could cause issues, although the drone could probably keep it stable.
For a future video, try mounting the wing below the rotors, this may seem more unstable but it's highlighted to be just as viable as above aerodynamically by the drone pendulum fallacy. Having the wings below will allow them to rotate without the consequence of hitting the rotors, potentially allowing you to bring the CoL closer to the CoG (although, I'm not sure whether the downwash from the rotors will impact this).
Great idea but I think it would need a rewrite to the controller. Combining what Zipline does with being able to take off and land anywhere would be great
You essentially made a canard aircraft without the rest of the air frame and gave it some alternative form of P thrust. Thinking about how it all interacts is making my head spin, so keep going and make more iterations!
The drone is missing some kind of more effective pitch control like in standard airplanes, i think this is causing the oscillations.
Also fins below the rotors maybe would prevent the rotation of the airflow, which could boost efficieny as well
I agree. I think the flight controller program would need to be designed for this hybrid design and also include servo control for wing pitch, and then it should be able to effectively counter the instability.
What if you put a servo on it? Going trough the fc gyro for pitch
I'd love to see you push this idea a bit further. an idea I had would be to have 2 wings across with 2 rotors set into each wing. That might give you more stability.
in any case, love the vids and cant wait for the next one!
That is exactly what I have seen patented
Your projects are so unexpected.
Love your ideas.
Late to the party, but I think the performance would be better with the wing mounted just below the props instead of above them. It'll also be a more compact overall package.
the down wash of the props would keep pushing the wing down aswell as messing with the airflow over the wing so idk if it would be better, would like to see it tested still
@@hazza2247 Think it would be more drastic than the props pulling the air past the wing in the current configuration?
@@Stormclowe i mean both are bad, i don’t know enough about this stuff to have anymore of an opinion
Very interesting, even to a non mechanical/non engineer amateur drone enthusiast like me. I subscribed after watching your first Dyson vacuum engine powered airplane flight . The more I watch, the more I'm hooked on watching your UA-cam videos. You're a very smart young whipper snapper.
And as I watch this video, it makes me proud to be from the Pacific Northwest. ( grew up in Bellevue) but live in downtown Seattle now.
Keep up the good work!
If you put a laser on it with longitudinal light, it will become one of the earth invasion films from before👽
Loved this video. Loved your approach to the experiment and the way you analyze the results. Speaks really well for the company.
Ok now we need to send this to Ukraine
I love the frequency of your video-output these days :)
Here's my silly idea: Instead of large solid foam wings, use small spools of fabric and pairs of linear tracks to create the airfoil.
Winches made with continuous servos will be used to extend the fabric, while the spool will be tensioned back by coil springs.
This could provide more adjustments besides rotation, as there's total control over the airfoil's surface area. For example, to retract it partially or entirely when hovering or in turbulence.
Wait a minute, did I just reinvent sails and repurpose it as a motorized kite...? 🤔
Sounds like a fun project.
Daniel, look into the “free-wing” concept. The wing adjusts the AOA automatically. Think you could build Rutans Scorpion as a model.
Put stabilize system into the wings to servo on either side
This is a fun experiment in seeing how positive you can possibly make Cm alpha.
Check out the British designed Fairey Rotodyne from the late 1950s. A single rotor was used for take off and landing and which was then then put into auto-rotation during level flight. Lift also came from 2 short span conventional wings where the propeller engines were mounted. The system worked well but the biggest con was the noise made by the rotor tip jets on take of and landing. Not a good point as the aircraft was intended to be operated from city centres. There was a hush kit in design when the project was cancelled but by then it was too late to get any more government funding :(
Finally! I've been periodical searching online to see someone do this... I've been thinking of it as an attachment to dji drones that already have long flight times!
Whenever I move to Washington in the future I hope I get to see your inventions getting tested around Seattle. How fun would that be to see some device and think "oh that's just rctestflight"
I actually made something a lot like this a few years ago, but for a 4' quad style base, and rather than 1 wing in the middle, I had 2 wings front and back. They were automatically put level with 1 servo that was linked to both of them. It kinda worked for the lift aspect but the control algorithm had a ton of trouble with it. I never ended up getting a chance to fix that though.
Nice work. Look at the scorpion/stargazer freewing UAV and design your wing the same way. Use a pitch neutral airfoil (flying wing airfoil) and you can remove the stops and have the wing self align regardless of airspeed. Aurora flight sciences also had a vtol with this idea many years ago
Agreed with all the comments about the CG vs center of drag, but something else that might be worth trying is no stop on the AoA and then some kind of tail boom and stabilizer attached to the wing in the same way those drone sailboats get the perfect AoA on their sail
I like the approach as I've made similar concepts some time ago. I used servo-like stabilized AoA of the wing to maintain constant angle regardless copter pitch and current sensor to get real power consumption. I notified significant gain in efficiency, however I dealt a lot on control algorithms as copter's autopilots does not like a wing to be attached and provide lift. It is bit misleading to autopilot, you increase the forward speed and you generate lift so it needs to decrease the thrust having less authority to control pitch, roll and yaw.
nice video! keep it up!
Thanks for another great video!
I was wondering, have you ever thought about giving a drone a body that acts as a lifting body? Or any other shape that generates lift?
There was a great Dutch project just like that see also Manna delivery drones
We need a UA-cam X-Prize for guys like you to encourage this sort of thinking and building.
@@jcd-k2s Not necessarily. There are ways to filter out the big guys.
Hey I work only five min away from Freefly Systems. What an awesome place to work!
A very interesting video. Surely, adding a tail with a depth rudder would greatly improve stability. Best regards.
@5:13! That's it! Nailed it! Not wrong. Right. That was the transition into lift. Freaked the FMC out though.
Have you considered a "freewing" system? Essentially, build the wing as a flying plank with a reflexed airfoil, or with a trim tab to adjust the reflex for different speeds, and then set the pivot so that it matches the flying plank's CG. With this setup the wing should hunt for the ideal angle of attack in the relative wind without needing a stop.
Wow, this idea looks great, but I would suggest to mount the wing further rearwards and with a fixed pitch angle because when the center of lift of the wing is behind the CG the wing actually provides positive pitch stability so it wont get into those oscillations. Also would negative angle of attack not cause the drone to crash because it would limit the maximum forward pitch of the quad. I really would like another video of this concept with some design improvements.
I was thinking the same thing about wing location. When the drone tilts forward, the wings move forward causing lift in the front so the drone tilts back, shifting lift to the back etc etc. I have no expertise though so was looking for a comment that was similar.
this was awesome, would like to see more of this type of thinking!!!
Would be interesting to control the wing pitch with an AOA servo to keep the wing at +5deg relative to the quad pitch angle.
7:35 lol this was awesome and so funny .. LOL ! great video man
I am currently completing my senior design and my project is a fixed wing (piper cub style) with vertical take-off and landing capability and a forward pulling traditional style motor. This is interesting because it's such a different approach from the previously mentioned Warwick university example. I would see this design being helpful at very slow speed but testing this to a slow flying fixed wing VTOL would be interesting to see what design is more efficient. could be useful for package delivery applications... maybe... as you mentioned high wind would be extremely detrimental to this design.
Amazing that you had people at work filming you doing your thing. That's so rare from my experience.
I don't want to give any suggestions but...The whole wing looks oversized. Try making it less wide (less wingspan) and possibly thinner with slightly reduced area and even 6 degrees dihedral. I believe it will help especially at 12+ m/s. I hope you can try again. Good Luck
Nice work .
Keep it up.
Also, the wing will be doing some crazy stuff to the airflow into the top and bottom pairs of rotors during the different flight regimes, potentially creating a negative feedback loop and reducing control authority - ie accelerating the air into the bottom rotors reducing their net thrust and slowing the air into the top rotors increasing their net thrust
A wing mounted on top, like Chocolate Rocket commented, added a pitch moment because the drag force is acting a distance away from the center of mass. On top of that, the center of mass has been shifted upwards, creating even more instability. To counteract both of these points, you could try sizing down the airfoils and adding equivalent airfoils to both the top and the bottom of the quad. You technically don't know exactly where your center of mass is unless you're able to model all of the parts in CAD and use an assembly to let the computer figure it out for you, but you can use intuition to approximate where it is. Even if the top and bottom airfoil aren't the same distance from the center of mass, the resultant forces and moments will bring the system much closer to stability.
It needs a tail with horizontal and verical stabilizers. 👍👍👍
In the hover (or "drone") orientation, having the wing above the center of mass increases stability. (In terms of forwards/backwards speed: going forward increases drag on the wing, which is above the center of mass, so it pitches you back, which decreases drag, and so on.) If your drone pitches forwards into "plane-like" orientation and tries to go fast, it is putting the wing in front of its center of mass - A very famous thing that is making a craft unstable.
There's 2 possible solutions:
*Either* move the pivot rod to *below the rotors* to get it to the same height as the center of mass or below it. In this case you'll loose the stabilization in drone-mode.
*Or* move the pivot rod further *towards the rear* of the drone. That will increase the stability in the airplane-like orientation. You can get away with keeping the wing above the propellers if your drone never pitches more than 35° or so down (which may _not_ be true, since I expect optimal efficiency gains close to 90° down pitch).
Good to see you in the air again.
Cool idea. We went through this with the UAVforge spy drone project. Fixed wing VTOL planes do exist. Motors are mounted on the wings, but the whole wing can rotate so it effectively becomes a bi-copter.
Two ideas that occurred to me watching this:
1.) Add four wings to a quadcopter where the propeller arms form the main spars. I think that with the right control algorithm you could directly control angle of attack (not just with ailerons/elevators), but could also purposely induce side slip/lateral motion without rolling or turning, which a conventional aircraft cannot really do.
2.) Create an aircraft with no control surfaces, that controls its orientation solely through rotating internal weights and conservation of angular momentum.
Wow , the exact idea that i even drawed it in my notes , thanks for creating it.
So, in my experience, drones often have to run their rear motors faster than their front motors when moving quickly because the faster they go the higher the righting moment in pitch due to aerodynamic forces. I don't know if that's universal, though. Maybe it depends on how your central body is shaped? But, as others have said, you are also getting a pitching moment from having the wings so high above the center of mass. Putting that all together, I'm impressed that it worked as well as it did.
I’ve been designing and flying RC planes for 40+ years. In order for this to have any chance of working, you need to do two things. First, get the center of mass (CG) of the drone about 35% back from the front of the wing. Second, use an accelerometer, servo, and small microcontroller that can adjust the wing’s angle of attack so regardless of the flight angle of the drone, you keep the wing’s angle of attack to the wind in the 0 to +3° range, depending on the airfoil. Otherwise, the wing just acts like a big sail.
Now that was a creative way of finding new employees.
Kudos!
Still comeing back for this nice idea to see the performance. No clickbait bullshit. Top.
Beautiful idea! I think your on to something there!
I figured the possibility was likely, but it's nice to see such a clear difference in the data. Very cool. :)
This channel has become my favorite out of nowhere.
Aeroespace engineering student here, those oscilations are caused by positive arch wings by definition having a positive pitch moment alpha derivative, thats why flying wings need to be delta shaped or atleast have some negative tip angle of atack so that the total pitching moment derivative is negative, crating a self stabilized flight
Oh, also, just a fun note, but the actual oscilations are caused by the angle of attack becoming so steep that the wing stalls and the nose falls back down and the cycle repeats again
Daniel: So, any efficiency increases?
Alta: I'm just fighting to survive!
So many questions I've wondered about answered!!
@rctestflight. Mind if I ask what current metre you are using. I was looking for a power logger for ages but could'nt find anything suitable.
Could you use glider wings pivoting at the center of mass of the rotorcraft? You might be able to make those clearances work with the downside of being much wider.
Thanks for the information!
Awesome work. Keep it up!
An idea I recently considered: Attaching helium filled balloons to a quadcopter to offset some of its weight and therefore reducing energy consumption for hovering. I have not gotten around to doing even some cursory math on how big these balloons would have to be to make any noticeable difference and so that the (volume of gas)/(weight of mount + balloon) works out to be at all productive, but I think it could be a fun thing to try. The attachment of the balloons would certainly have to be static, so that it is not a quadcopter swinging around helplessly on a cord below a balloon, and the large surface of a balloon could create some real problems with wind. Idk, maybe one could design a funky looking quadcopter airship.
Very cool experiment dude, keep up the good work
i think this is the application of tilt rotor aircraft.
Being able to rotate the propellers forward allows the payload to stay in the same orientation while flying vertically and laterally.
Love it!!! one thing we didn't see was the wind direction, which could have explained the no thrust motor. and as other said, think the wings need to be closer to the center of mass, or maybe double them up as a large biplane?
Awesome idea to improve drone efficiency!
I think the main cause of instability is the aerodynamic pitch instability induced by the airfoil. As soon as the wing starts flying. Every normal aircraft needs to adress this problem. Usualy its done by choosing diferent agles of incident between main wing and tail wing. The simplest way to fix this on your drone would be probably by using a stable airfoil like its used for flying planks. No need for a tail anymore.
Not baaaaaad! Interesting idea, please continue testing! :)
Build one you can fly yourself around, everyone seems to place the pilot at or above the rotors, on a hard landing the pilot could be thrown down onto the rotors, and if the pilot is at rotor level a blade could snap and impale them, i'd like build my own with a fuel engine with two counter rotating props for the main lift, and four battery rotors for control. really enjoy your videos
The best example to take inspiration from for fixed wing efficiency & Quadcopter type VTOL (vertical take-off & landing ) performance will be a US made military aircraft called V-22 osprey .
Hope some makes a RC drone based on it
Could a rear stabiliser be attached to the wing spar, reaching back between the rear rotors I wonder? So that it could pivot with the wings, but not be affected by the rear rotor wash. Almost like a quad/ultralight? Hmm.
That was my first thought!
I wonder what would happen if you added control surfaces to the wing for pitch control, and then added some sort of basic gyro stabilizer to control them. Independant of the flight controller on the quadcopter. Or maybe some sort of mechanism to control angle of attack in the same way
That's what I was thinking. Stage 1 add control surfaces which try to keep the wing AOA independent of drone AOA. Then stage 2 could be adding roll control assistance stabilization.
Great video, thanks a lot for this story, and for the already thorough analysis. We have similar ideas, that we should try in the next months, I'm looking forward to being able to report on our own progress.
How do you calculate for wind variation between fixed wing and just the rotors?
Drone programmer here, the wing seems way too complex system for the PID to handle, especially may be the following: at speed X, the wing is pushing you UP, and if this is more than the drone can compensate lowering motor speed, it goes crazy. Also sudden loss of lift (stalling) is something PID cannot handle.
Also, where is your center of lift?
PID are a more a final touch, the more the drone guidance know about its physic, the better result you have
Edit: if you would ask me how to start programming this, i think that first think you need to control electronically the pitch, or you cannot handle dynamic speed, you have one speed that is your most efficient and you cant exceed without keeping altitude requirements.
I would create a test in something like xplane, as it does actually simulate propeller physics and other aero property; and create a table to what best pitch give the best result. It is simply too many hour to properly create an optimizer , the lookup table is the best. Also while the wing are engaged, you probably want to use less motor and more wing control, as the wing itself will stabilize pitch roll and yaw.
Feedback: one way to avoid negative pitch moment at high speeds is mount a fixed-pitch wing forward of CG (1-3 degrees positive AoA); a slow climb is way better than a high speed crater
Next experiment: Place the wing below the rotors & fix the pitch (to eliminate oscillations). Test your theory regarding rotor wash. You might also want to experiment on wing placement (test forward of CG & aft of CG).
One key difference with the flight testing in this video is the all-up-weight of the drone was not the same with and without the wing. When flying without the wing an equivalent amount of weight should have been carried by the drone. Expect we'll see much better efficiency when the challengers have same AUW. (12:28)
To avoid sketchy flight maneuvers, it would help to add a radius between waypoint legs. Those 180º turns are just asking for craziness. Not having a fixed wing (non-pivoting) would cause he centre of lift to vary as pitch angle varies. Location of centre of lift vs. centre of mass can effect stability.
Overall a fascinating experiment Daniel. Like how you totally skipped any testing with a robust 5-inch, or 7-inch freestyle quadcopter and went straight to flight testing on a 13-inch monster-copter.
Damn is that your garage with the X5 in the background? Looks like an awesome garage or workspace.. Cool video like always! Thanks
Separate the wings by more so they are outside the area of the rotors . Also id lose the pitching of them. Not quite fixed but way less movent away from facing the way a wing should.... You know better than me AND know the quad but that still seems like what it wants..... Keep them coming dude! I love your videos. They're like mental chewimg gum.... 😎 Also.... It might be worth at least trying having the wing UNDER the rotors.... You never know it might add the low pressure needed above the wing if its at a helpful angle or something. In any case i think getting the wimgs outside of the rotor footprint would be a very good thing......
how does this compare to tilt rotors? this actually has some really interesting utility for giving extra range to infiltration and reconnaissance drones
Great work . I like the way you think .
I had that thought for my Chimera 7 built , but I had my hesitations .
Not any more 👍