Spot on.

Great points!

Sure. The motivation is the same.

Thanks! The balance we are striving for is useful information without extrapolating from dogma. If the viewer comes away thinking "now I get it, it's not really complicated and I bet I could do something even better if I just tried..." Perfect. Your suggestion about the bolts is excellent. Explain the engineering principal of mechanical modulus, find an elegant way to drill out existing aluminum hardware, test the practical balance of strength vs lightness and that would be the kind of video we would do.

nomenclature? wtf iz that? he never mentioned it.

@@weatherphobia lol, the irony. It's the lexicon used in a domain

Thanks. Have you taken a look at some of our other videos?

I will be, your edification rate sync's nicely with my receptors.

Great!

Thank you for watching and for your support.

Wow, thank you!

Ask for adoption?

Thanks!

I have a question, how do you make the least amount of supersonic drag?

I keep saying that! My family just rolls their eyes.😕

Thanks!

Thanks! You're suggestion might be a little lighter, but it probably won't be stronger. The spar can't accommodate a larger diameter aluminum tube, bolt etc.

Thanks!

Carbon is conductive, but not very much. That means it is very efficient at turning electricity into heat. The energy lost would almost certainly be more than the weight savings of some wire.

Thanks! I assume the viewer genuinely wants to understand and is able to understand. All I have to do is link principles to what is already known.

You're point about kevlar is true. Sometimes it is misunderstood that blending the kevlar and the carbon produce a superior composite other than Kevlar's ability to stabilize fragments.

Headroom,was a figure of speech to indicate that the motor is operating with a voltage drop of approximately 70% of the battery supply voltage. If we were using 8s batteries, the motor would be operating at approximately 35% of the supply voltage.

17:20 it is a matter of duty-cycle. At low demand there will be low duty cycle and that causes high switching loss. There isn't actually a voltage drop but for the moment of switching.

Thanks!

Boy, you have a lot of interesting ideas. Some we have considered, but many we have not. Larger radii? Do you mean larger outboard positioning of the aluminum folding brackets, larger spacing of the pivot screws or larger tube diameters. There are trade offs for each of these decisions, but maybe you meant something else. For the larger and many of the smaller Nylocks we have converted to aluminum. This was an EASY improvement...many are not. Strength is rarely an issue with fasteners for these craft, but point loading is. Load distribution with the lightest fasteners that are practical is often preferable. Titanium is not likely to be an advantage unless we wanted to sell this project and we needed to make the brochure sexier. The large rotors we built in subsequent videos were much easier to construct with a flat lower surface. A different construction method might allow this degree of freedom. Why would airfoil symmetry vs say AOA be useful near the motors?

Well, sometimes the obvious eludes the genius? I should think that the point of diminishing returns is not far off from your design, but are a few grams here and there that might be saved, which add up, and add up to a few more seconds of flight--or a slower decent on a hard landing. I meant a larger radius on the metal bracket, which holds long carbon spars/struts (which hold the motors.) Sometimes, when I draw up things, I ask myself: what has the right and justification to be here. I haven’t seen aluminum Nylocks. Interesting, thanks. Yes, I should think that point-loading / stress concentration is difficult because-not only because carbon fiber a little brittle, but it is so stiff elsewhere which yields little. I’ve worked with fiberglass a fair bit, but that’s much more forgiving. I thought that the spars/struts could be given a symmetrical airfoil shape to let the air pass around, to minimize the stagnation around the sides of the tube. Merging in with your box attachment idea, I drew up this quickie Rhino3D drawing. I’ve tried to keep the faired airfoil shape constant to the edge of the prop. www.dropbox.com/s/advi8vwf804woqw/Quad%20End.jpg?dl=0 Cheers P.S. Some free stuff: openfoam.org www.salome-platform.org/ code-aster-windows.com/ www.code-saturne.org/cms/ www.paraview.org/

Remember the old adage, "A good tool is one you can't add anything to and a great tool is one you can't take anything from". I appreciate your approach. You might find it interesting to take a look at the history of the development of the early Lotus automotive racing team. They carried this philosophy literally to destruction! Nice CAD. Now, I understand your comment about the arms, interesting, but remember the greatest impact will be where the rotor-wash velocity is greatest. Also, keep in mind that the arms have to resist torsional forces to prevent the discs from oscillating when maneuvering. They will need an increased cord length to compensate for the narrower profile. Still don't understand about the brackets. They are more massive than the arms and the central plate is heavier than both.

Interesting conversation you guys have been having! On the topic of the fasteners and the stiffness of Carbonfiber: I would estimate you could go down 1-2 sizes of fastener where your booms are attached if you cut a solid block of nylon or maybe balsa to fit inside the tube, with holes drilled through it for the fasteners. That would allow you to clamp down hard without any worries, and it would spread the radial load from the bolt along the whole cross-sectional area of the tube as well Beautiful bird! Almost twice the size of mine

Thanks!

On drone charging is the future. Roll with it.

Yeah, drop and roll.

The lift lost to the dihedral is quite small and reduces the demands on the active stabilization because the effect of the dihedral is instantaneous, there is no lag and concern regarding dephasing. This is why most aircraft have a dihedral in that it decreases the demands on the pilot. We also placed the batteries in the center and below the craft's center of gravity to enhance stability. Very large multi rotors do not have the same maximum lift/ weight ratio as small, highly powered craft and are slower to respond to flight corrections. inherent stability is a big advantage.

​@@TechIngredients Absolutely! Ultra heavy lift drones (50 to 250 kg of payload) have not only less lift/weight ratio, but also different flight characteristics because of inertia. We can not build a racer drone in such a scale. If a small racer drone can make, say 3 flips per second, then in large drone case it would not be possible to do at all. Even if it was physically done, the drone would just disintegrate mid air. Putting batteries closer to the motors would affect drone maneuverability especially around yaw axis (it is easier to start spinning empty carousel than full of kids). Drone has to be built so to survive also some harder landing and not just to support its own weight. Moving more mass farther from the center on the booms would cause higher load in the root of the booms and could easier “fold” them to the ground. Distributing mass closer to the center of gravity is right also because heavy lift drones usually are not made for flying around unloaded but made to lift things and the load is attached in the line with CG, otherwise the flight becomes inefficient because of uneven motor loading and reduced power reserve for more loaded motors.

Typically those elevators are constructed from concrete segments and concrete has good compressive strength, but very poor tensile strength. This is the principle that underlies pre stressed concrete engineering. Carbon fiber has balanced compressive and tensile strength and the value of additional stringers would be low.

​@@TechIngredients I was referring to the grain tubes that feed the grain from the leg, to the top of the silos. Without the tension wires, they would fold under their own weight.

Thanks for the suggestion. We're working on several new ones right now.