Pretty damn impressive. Im not very computer inclined but i know quite a bit about aerodynamics and physics and i bet not too many people grasp how technically challenging that is. Very cool!!!! Absolutely amazing!!!!
> I know quite a bit about aerodynamics and physics Let's maybe try to solve the CX7 not-exactly-Coanda problem then? (The last CX7 video on this channel is dedicated to it) I've talked to some fellow physics people about that machine. They all thought that all the problems came from insufficient control authority of flaps. The CoG is indeed not very high, and the flaps are primitive, but the stand test showed that there is something they missed, something we don't understand where it comes from. I'm saying Coanda, but the duct on CX7 is just a thin wall, literally a plastic bottle with some 4mm printed structural rings. There is no dedicated surface which increases lift but is subject to asymmetrical forces when flying in the wind - and I feel there is something that we have all overlooked. I observe this all also on SN1, which has a much higher CoG and an even smaller top surface. Could you maybe have a look?
How cool! It looks like the Hiller Flying Platform, so if you have the mass budget for a some sort of human "doll" disguise for the control module that could be a fun look. Like, it could be a small cloth cover to look like a simple cloak, and then just a doll head at the top. One type of drone I'm fascinated by is the monospinner - a single prop drone with no flaps. As such, the body of the monospinner does inherently yaw - but this is part of the control. As it yaws (spins) in place, the prop is throttled on/off cyclically in order to provide control. You could tilt the motor/prop by, say, 15 degrees, so the prop nutates in place.
I can easily imagine attaching a 3D-printed head to the top of this. With some lights added, it can make a nice Halloween trick. The question of proper clothing is less trivial though... For the monospinner, I liked quite much the extension of this concept into a "large propeller" by Nicolas Rehm. Currently I'm not quite interested in vehicles with reduced degrees of control, but who knows: the more you build, the more you want to build :)
My other active vehicle, CX7, is even more like the Hiller Flying Platform, and it even has some similarities in aerodynamic deficiencies (which I hope to overcome, which the original platform could not do).
It requires bigger and better control surfaces though. For pitch and roll, the force arm is from the CoG to the lift application point of a flap, and is easily controllable by where you put your battery. For yaw, it is the distance from the central axis to the same point, and cannot be changed much without starting from scratch, so only increasing flaps (to increase the force) is the way to deal with it. Once I am done with the main test program for this machine, it is likely I will perform tests on how different flap designs work. Likely, by putting the reference design on roll servos, the tested design on pitch servos, and doing some flights and log analysis.
@@wowthatflies What system would you think is more efficient, single rotor which deflects air to counteract the torque or a coaxial? I watched that video you suggested on the conada effect of ducted flying platforms. Made perfect sense. 👍I see this model isn't ducted so won't be affected by the coanda effect.
SC1 does not seem to have this Coanda problem indeed. Generally, a single rotor, at least on a smaller scale, should be more efficient - per unit of power - than coaxial rotors, because the efficiency of the lower rotor is smaller as it has to work with turbulent air. But other design considerations turn that into a fight of engineering trade-offs: like, how many additional structures you need to get a single rotor work, and how much they add to the overall weight, and so on. Per unit of mass, the single-rotor SC1 hovers at roughly 185 watts/kg, while the coaxial CX7 hovers at roughly 308 watts/kg. (These are random single-point measurements, so take this with a grain of salt anyway). The ratio is 5/3 in the favor of SC1. But SC1 uses a 10" prop, whereas CX7 uses 5" props, and the huge motor of SC1 definitely has more efficiency than two much smaller motors of CX7. So the comparison is obviously not very clear. It seems that the choice of motors and propellers may have a comparable or even bigger impact on efficiency than single vs coax. Losses on control surfaces should be smaller in coaxial designs, as they don't have to be constantly at a noticeable angle to the flow. Bigger surfaces will need smaller angles, but they will introduce more drag. A trade-off theater indeed.
I'm glad you liked it! This is definitely not the first singlecopter ever, and not even the first on UA-cam. Maybe the most popular design is like this: ua-cam.com/video/LGTTuYx5jpo/v-deo.html, also built by this guy: ua-cam.com/video/YdvwP_g6c2M/v-deo.html and many other makers. My build is a little bit special because it uses single-blade flaps instead of "grid fins", and because it can be converted to three blades in a matter of five minutes. It appears to be somewhat more stable in yaw, but that's probably due to a different firmware with a different control algorithm. For the video format, I usually release a video per day of testing, but this time testing was quite tight in time, and I thought it may be more natural to make a single video for this.
We all learn something, all the time. For SC1 to fly well, I had to set the yaw error filter to zero. Looking back, I should have done that for my bicopters too, two years ago. And since you were actually flying the SingleCopter version, you would have benefitted from this too...
This one has two test programs in plans. The main one is about testing different arrangements of flaps (more specifically, related changes to control algorithms). The one that will likely follow is about different flaps themselves, like how much worse a flat flap is compared to an aerodynamic one, or how grid fins behave in comparison with single-blade flaps. This is all somewhat conservative because a hard crash would effectively result in rebuilding the entire vehicle, which I would like to postpone as much as possible. What follows after these test programs, however, can be much more risky and exciting...
In the flight logs I already see some resonances related to either flaps or the frame. A flexible frame would only get it worse. A better solution is to separate structural strength and shock absorption by adding some soft landing endpoints to an otherwise rigid frame, like I did on two other vehicles. This one just has too many legs :) but quite likely I will do something like this here as well.
You would need to consider what thrust can a cooler fan generate, then think what mass budget you have, where you have to fit a frame, batteries, electronics, and maybe some additional components like servos. I think there are videos of quadcopters built with such cooler fans, which fly, kind of. Depending on what exactly fans are used, controlling their speed with necessary precision can be a challenge. Singlecopters don't seem to require as sharp and precise control as quads do, but you still want to be quite exact with throttle.
Its own wet weight, in the flying configuration with big flaps and extended legs, is 840g. The second section of the video featured an added weight of 540g, which still lifted off easily. The motor test data says on 6S the maximum thrust of this motor/propeller pair is around 4.4kg, so assuming cosine losses for 45 degrees and a bigger wet weight of 900g, theoretically the payload can be up to 2kg. The current frame design was not made for large payloads though (and even not for hard crashes), it's mostly a test vehicle for modifications of control algorithms.
I would rather say PETG-CF, since unlike planes it cannot handle loads by the whole volume - as there is no particularly big volume. Except for flaps: flaps should be ideally made of LW-PLA indeed (or fiberglass for hardcore makers). Ideally, the top assembly that supports motors and directs loads to legs should either be made of carbon or be designed in a more rigid way (in particular, to be non-flat). And for the sake of letting in more air it should rather reduce volume than strength, so my heuristics say LW-PLA is not exactly suitable for the frame.
Two other coaxial machines I'm working with have ducts, and currently I have very mixed impressions about them. I will probably do my own experimental research about ducts when I have enough time...
![SN1 :: [2024-10-09] :: The Landing Cage](http://i.ytimg.com/vi/NPzsj6PMu3k/mqdefault.jpg)
Pretty damn impressive. Im not very computer inclined but i know quite a bit about aerodynamics and physics and i bet not too many people grasp how technically challenging that is. Very cool!!!! Absolutely amazing!!!!
> I know quite a bit about aerodynamics and physics
Let's maybe try to solve the CX7 not-exactly-Coanda problem then? (The last CX7 video on this channel is dedicated to it)
I've talked to some fellow physics people about that machine. They all thought that all the problems came from insufficient control authority of flaps. The CoG is indeed not very high, and the flaps are primitive, but the stand test showed that there is something they missed, something we don't understand where it comes from. I'm saying Coanda, but the duct on CX7 is just a thin wall, literally a plastic bottle with some 4mm printed structural rings. There is no dedicated surface which increases lift but is subject to asymmetrical forces when flying in the wind - and I feel there is something that we have all overlooked. I observe this all also on SN1, which has a much higher CoG and an even smaller top surface.
Could you maybe have a look?
Really good job
How cool! It looks like the Hiller Flying Platform, so if you have the mass budget for a some sort of human "doll" disguise for the control module that could be a fun look. Like, it could be a small cloth cover to look like a simple cloak, and then just a doll head at the top.
One type of drone I'm fascinated by is the monospinner - a single prop drone with no flaps. As such, the body of the monospinner does inherently yaw - but this is part of the control. As it yaws (spins) in place, the prop is throttled on/off cyclically in order to provide control. You could tilt the motor/prop by, say, 15 degrees, so the prop nutates in place.
I can easily imagine attaching a 3D-printed head to the top of this. With some lights added, it can make a nice Halloween trick. The question of proper clothing is less trivial though...
For the monospinner, I liked quite much the extension of this concept into a "large propeller" by Nicolas Rehm. Currently I'm not quite interested in vehicles with reduced degrees of control, but who knows: the more you build, the more you want to build :)
My other active vehicle, CX7, is even more like the Hiller Flying Platform, and it even has some similarities in aerodynamic deficiencies (which I hope to overcome, which the original platform could not do).
Brilliant work, I didn't think it would be possible for a single rotor to work like that. Certainly simplify's things without needing a coaxial rotor.
It requires bigger and better control surfaces though. For pitch and roll, the force arm is from the CoG to the lift application point of a flap, and is easily controllable by where you put your battery. For yaw, it is the distance from the central axis to the same point, and cannot be changed much without starting from scratch, so only increasing flaps (to increase the force) is the way to deal with it.
Once I am done with the main test program for this machine, it is likely I will perform tests on how different flap designs work. Likely, by putting the reference design on roll servos, the tested design on pitch servos, and doing some flights and log analysis.
@@wowthatflies What system would you think is more efficient, single rotor which deflects air to counteract the torque or a coaxial?
I watched that video you suggested on the conada effect of ducted flying platforms. Made perfect sense. 👍I see this model isn't ducted so won't be affected by the coanda effect.
SC1 does not seem to have this Coanda problem indeed.
Generally, a single rotor, at least on a smaller scale, should be more efficient - per unit of power - than coaxial rotors, because the efficiency of the lower rotor is smaller as it has to work with turbulent air. But other design considerations turn that into a fight of engineering trade-offs: like, how many additional structures you need to get a single rotor work, and how much they add to the overall weight, and so on.
Per unit of mass, the single-rotor SC1 hovers at roughly 185 watts/kg, while the coaxial CX7 hovers at roughly 308 watts/kg. (These are random single-point measurements, so take this with a grain of salt anyway). The ratio is 5/3 in the favor of SC1. But SC1 uses a 10" prop, whereas CX7 uses 5" props, and the huge motor of SC1 definitely has more efficiency than two much smaller motors of CX7. So the comparison is obviously not very clear. It seems that the choice of motors and propellers may have a comparable or even bigger impact on efficiency than single vs coax.
Losses on control surfaces should be smaller in coaxial designs, as they don't have to be constantly at a noticeable angle to the flow. Bigger surfaces will need smaller angles, but they will introduce more drag. A trade-off theater indeed.
Man that is really innovative!! Never seen a system like that until now, and the testing-stages video format was awesome!
I'm glad you liked it!
This is definitely not the first singlecopter ever, and not even the first on UA-cam. Maybe the most popular design is like this: ua-cam.com/video/LGTTuYx5jpo/v-deo.html, also built by this guy: ua-cam.com/video/YdvwP_g6c2M/v-deo.html and many other makers. My build is a little bit special because it uses single-blade flaps instead of "grid fins", and because it can be converted to three blades in a matter of five minutes. It appears to be somewhat more stable in yaw, but that's probably due to a different firmware with a different control algorithm.
For the video format, I usually release a video per day of testing, but this time testing was quite tight in time, and I thought it may be more natural to make a single video for this.
@@wowthatflies thanks for sharing those videos! Now I've got a new rabbit hole to go down! 😅
I read that one forum page you wrote about this like a hundred times while I was making my coaxcopter.
We all learn something, all the time. For SC1 to fly well, I had to set the yaw error filter to zero. Looking back, I should have done that for my bicopters too, two years ago. And since you were actually flying the SingleCopter version, you would have benefitted from this too...
Fuuuuuun! It's always nice to see new stuff being tested. Kudos! I subbed so I can see what happens next. 😁👍
This one has two test programs in plans. The main one is about testing different arrangements of flaps (more specifically, related changes to control algorithms). The one that will likely follow is about different flaps themselves, like how much worse a flat flap is compared to an aerodynamic one, or how grid fins behave in comparison with single-blade flaps.
This is all somewhat conservative because a hard crash would effectively result in rebuilding the entire vehicle, which I would like to postpone as much as possible. What follows after these test programs, however, can be much more risky and exciting...
@@wowthatflies can you make a more flexible frame to absorb impacts and keep the stiff flaps? Or would there be added issues with stability?
In the flight logs I already see some resonances related to either flaps or the frame. A flexible frame would only get it worse. A better solution is to separate structural strength and shock absorption by adding some soft landing endpoints to an otherwise rigid frame, like I did on two other vehicles. This one just has too many legs :) but quite likely I will do something like this here as well.
I was thinking about making a drone with a cpu cooler fan, this is the closest thing that idea that i found, very well done
You would need to consider what thrust can a cooler fan generate, then think what mass budget you have, where you have to fit a frame, batteries, electronics, and maybe some additional components like servos.
I think there are videos of quadcopters built with such cooler fans, which fly, kind of. Depending on what exactly fans are used, controlling their speed with necessary precision can be a challenge. Singlecopters don't seem to require as sharp and precise control as quads do, but you still want to be quite exact with throttle.
nice
What's its payload capacity ya, any idea
Its own wet weight, in the flying configuration with big flaps and extended legs, is 840g.
The second section of the video featured an added weight of 540g, which still lifted off easily.
The motor test data says on 6S the maximum thrust of this motor/propeller pair is around 4.4kg, so assuming cosine losses for 45 degrees and a bigger wet weight of 900g, theoretically the payload can be up to 2kg.
The current frame design was not made for large payloads though (and even not for hard crashes), it's mostly a test vehicle for modifications of control algorithms.
@@wowthatflies if it's 3D printed means better try LW-PLA ya
I would rather say PETG-CF, since unlike planes it cannot handle loads by the whole volume - as there is no particularly big volume. Except for flaps: flaps should be ideally made of LW-PLA indeed (or fiberglass for hardcore makers).
Ideally, the top assembly that supports motors and directs loads to legs should either be made of carbon or be designed in a more rigid way (in particular, to be non-flat). And for the sake of letting in more air it should rather reduce volume than strength, so my heuristics say LW-PLA is not exactly suitable for the frame.
you should make a duct ..
Two other coaxial machines I'm working with have ducts, and currently I have very mixed impressions about them. I will probably do my own experimental research about ducts when I have enough time...