> Your run of the mill quadcopter is an ideal example of just throwing together motors + batteries + tech and getting a flying machine out of it.

There's the old saw that airplanes fly using lift, but helicopters fly by beating the air into submission.

Helicopters fly by trying to tear themselves apart, and mostly failing at this.

> the art/science of aerodynamics in modeling has fallen by the wayside.

You are not wrong. That is a valid lament.

But, this is the definition (or at least a very common result) of innovation/progress.

Tech/automation advances to the point that non-artists, non-experts can do a thing competently or even expertly. Photography use to require expensive equipment, skill, and knowledge. Modern advances in digital sensors/lenses/flashes/post-processing makes everyone able to take professional quality photos. There is, of course still masters and talented artists that surpass. But the floor for everyone has been brought up to expert level at least.

Same for film/video, driving, complex maths, and many more.

> Modern advances in digital sensors/lenses/flashes/post-processing makes everyone able to take professional quality photos.

For newspapers, maybe, but the tiny optics on phones rule out a lot of photographic techniques, to say nothing of sensor quality when trying to pull 20+ MP out of a sensor the size of a tab of acid

My iPhone 11 Pro still takes crap pictures compared to my FX (or even DX) camera body, and that's with all of Apple's idiot-proofing AI bullshit

Of course, otherwise those fancy cameras would have no market and disappear. Just like film is pretty much completely gone now, as are glass plate cameras. The truly inferior tech disappears and what's left fits some extreme niche where it surpasses the cheap consumer stuff in some way. There are things you can do with a PC that you can't with a smartphone too.

That's incredibly optimistic of you to call the PC dead. I really, really, hope (and am pretty sure) that you are wrong

I think the death of the PC won’t happen until phones and similar have the same power user capabilities as one. As long as we need a PC to build things for our phones, they’ll exist in some form.

The PC for everyday regular usage though is indeed dying. My girlfriend has an iPad Air with the keyboard case from Apple and it’s her primary computing device!

Not death of the PC! Just the presence of more numerous and cheaper smartphones. They're superior to PCs for most people but not for everyone.

It's a matter of scaling laws. You don't see insects or hummingbirds gliding anywhere, small things fly differently.

Butterflies do glide sometimes.

Dragonflies, too. But it's true that they can only do so for short distances. I don't think I've seen either glide for longer than a meter.

Lol

And dangerously. There is no redundancy.

For insects, hummingbirds, and quadcopters of similar size, there’s no danger in dropping from the sky.

J.S. Haldane in “on being the right size”:

“You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom it gets a slight shock and walks away, provided that the ground is fairly soft. A rat is killed, a man is broken, a horse splashes. For the resistance presented to movement by the air is proportional to the surface of the moving object. Divide an animal’s length, breadth, and height each by ten; its weight is reduced to a thousandth, but its surface only a hundredth. So the resistance to falling in the case of the small animal is relatively ten times greater than the driving force.

An insect, therefore, is not afraid of gravity; it can fall without danger, and can cling to the ceiling with remarkably little trouble.”

(These wing suits are man-sized, so they would break their wearer on impact)

> A rat is killed, a man is broken, a horse splashes.

I had thought that cats could fall from any height safely, but that's not quite true: observational studies suggest [0] they have a 50% or 90% survival rate from terminal-velocity height onto hard surfaces, but not without injury.

Still, I'd expect a rat could also "walk away". It's quite a lot smaller than a cat, though it may lack other evolutionary adaptations for falling. And a rat is a mouse, taxonomically: we just informally call the bigger species of mice rats.

[0] http://www.todayifoundout.com/index.php/2010/11/domestic-cat...

The dual taxonomy of so many animals is interesting. The line between a pigeon and a dove seems to be one of judgment, like with rats and mice. Or the slightly more distant mantis and roach.

Not quite. http://www.ratbehavior.org/RatsMice.htm http://www.ratbehavior.org/RatMouseHybrid.htm

Rats lack the long legs of cats that allow them to cushion their fall, though. Cats have a ton of adaptations that each help with some aspect of landing from a fall.

a huge portion of that is that humans have a much worse weight to surface area ratio, cats hit at about 60mph and humans at 120 mph. very few humans survive falls in which they reached terminal velocity.

I don't understand the lasting appeal of quadcopters in particular. We can build remote-controlled 'normal' helicopters that have fantastic performance and much greater efficiency (no need for 4x the motors and stubby blades).

The only downside I understand is that R/C helicopters are very difficult to fly, but that should be straightforward to overcome by putting a basic computer + sensors between the controller and the servos - the user could control the helicopter as if it were a quadcopter, and the electronics transforms those inputs with its sensors/gyros to control the helicopter appropriately.

This would seem to save costs due to fewer parts, lower weight, better battery efficiency, etc, but no-one seems to do it. I must be missing something?

Quadcopters are enormously more robust. With an RC helicopter any hard landing probably means replacing hundreds of dollars of finicky bearings and swash plates. Racing drones on the other hand smash into stuff all the time and keep going.

I think a large part is that they’re inherently safer with four smaller propellers rather than one big one. So suddenly applications where you’d need a helicopter are accessible to people with less training and skill. Particularly with the robust flying assists and mechanical simplicity.

Then they also turn out to be a readily accessible tinkering hobby very suited to flying around in areas people have nearby. The whole FPV and racing scenes bought in a demographic shift compared with helicopters and fixed wing. Quads are also fantastically agile so quite a different experience to anything else.

Most quad copter blades won’t go through your skull:

https://abcnews.go.com/US/minute-mechanical-error-led-teens-...

Proper helicopters also require a complicated control linkage on the main rotor and a separate tail rotor. Quad copters (and other multi-blade devices) only need to modulate power to the rotors for control.

I would never ride a quad copter, but they’re better for unmanned use.

I think you are probably correct about creating an easier to fly helicopter using a intermediate processor. I also think the argument of longer flight times due to less power draw may be true also.

But cheaper and fewer parts I'm not so sure, part of the reason drones are so popular is the low parts count and part price.

Most low price hobby copters use 3 motors, driving two opposing rotor blades for stability and a tail blade for steering. There are also several gears and bearings to support their functions. Far easier to strap 4 motors with props to a cross and drive them using a solid state SBC integrated with RF,6 axis gyro and 4 power transistors.

Many of these new hobby drones use all the same parts across several different manufacturers so there is an economy of scale to considet too.

Having 4 weaker motors is generally safer than one big one if something were to hit it, and you can shorten the blades because the lift is spread across 4x as many blades.

Multiple motors is good as well for any motor failures, as quads (if they're well designed) can fly after even multiple motor failures.

With a helicopter, even if you lose the motor (lift) you still have control by adjusting the pitch, angle and ratio of the blades.

A quadcopter depends on the motors for any control. While it is possible to regain control after a single motor failure on a quadcopter, it's extremely difficult and not something a human pilot could do, so you'd be relying on software. Also, if you don't detect the failure instantly, the craft will flip over before the software can react because of the inherent instability.

Any solution where you have some kind of passive lift and inherent stability (eg. parachute, wing, etc.) is always going to be much safer.

Would a proper parachute on a quadcopter be fine in case of motor failure / etc. be okay, then?

Multirotor designs are not limited to 4 motors. You can add more for redundancy. Four is common because it’s the smallest number that has good control characteristics.

Mind explaining that one? To me it seems they have an unnecessary degree of freedom: the "diagonal" one.

    ox
    xo

What issues do you get with three motors in an equilateral triangle?

EDIT: I managed to find it, with even number of motors you can prevent unwanted yawing, by letting half spin clockwise and other half spin counterclockwise.

Yep. More generally, you can induce the yaw rate you want (up to a limit) in either direction, including zero.

I’m not an expert but IIRC with three rotors you need to be able to control a bit of roll of just one of them to have stable flight control.

As they say "If you're in a helicopter and the fan goes off, you'll start sweating" :)

If you lose power on a quad they become unstable, if you lose power on a heli you can pitch the blades slightly downwards which keeps rotation in them and level out close to the ground landing perfectly smooth. IIRC this is something you practice to get your license. Can be done with both RC helicopters and real ones.

But brushless electric motors are so much more reliable than combustion engines (internal or turbine), the comparison is not even funny. They are basically solid state devices. "Losing power" is simply not much of an error state outside of complete battery failure. And if you still want to be safe from motor failures (or from propeller failures), octocopters exist. I share the "multicopters are boring" attitude, but they are boring for a reason.

Absolutely, as long as they're operating within parameters there's no failing them. I've been running brushless systems in RC cars for the last 7 odd years. The only motor failures has been when It's been subject to extreme abuse, as in the rotor reaching 100+° (internally), going from ~55-60K RPM to 0 in fraction of a second or the rotor being forced through the bearings.

For unmanned flight i do agree on multicopters being the best option. See this[1] video for an example of a multicopter flying with disabled props.

However, as you see this flightmode isn't appropriate for human beings, humans should keep flying helis for now. The swash plate design even though more complex than a prop mounted on a shaft is still a rather simple design, litterally a bearing mounted on a 2 axis system and rods attached to rotate the blades. Multicopters with swash plates are interesting too as they can be simplified not to tilt the plate but only offset it up and down to alter pitch the same way all around the rotation. If. This exerts less force on the bearing, but considering there's still 4 of them rather than one might increse failure rate. With swash plates on multicopters we could have two motors driving one system that drives the props, and do many amazing things with computer aided controls in case of failure.

Idk why i keep on going, TL;DR: Being able to control pitch is key, multirotor or not.

I'm not really with Elon Musk on alot of things, but personal human flight is one thing where i agree with him, It's not going to happen.

[1]: https://www.youtube.com/watch?v=w2itwFJCgFQ

Well, simple propeller pitch control is a lot easier than a swash plate because it's idle when the pitch is kept the same and it's no problem if making it slower simplifies it. A swash plate is active on each rotation and needs to be fast enough to work the blade through a certain range of pitch values within have a rotation interval.

I don't think a quadcopter is controllable with 3 engines.

However, a drone designed to carry pax can be designed with redundancy - the Volocopter, for example, has 18 rotors and engines, and can withstand at least 3 failing.

Mechanical simplicity in not having rotating blades I think is a big part of it. Its a lot easier to just use more motors and a 3d printer for the body then design the complex blade control system for a helicopter.

You're just vastly underestimating the stability four rotors bring. They're not flying in a vacuum. There are gusts of wind on top of actually moving the copter where you want him to go.

That can't be reasonably compensated by unless you use a processor which requires way more energy then the rotors ever will.

Fantastic performance as in? Quadcopters routinely reach 60km/h, and cheap racing models can go over 100km/h. I doubt any kind of heli will ever perform like that

One could argue that the increase in hardware performance of computers has led to the art of software design falling by the wayside. Horribly inefficient software runs because the hardware performance hides the truth under the hood.

That in theory gives a programmer who does care about performance an edge: they can leverage the amazing performance of modern day chips in a way that the average product doesn’t, and it should mean a business advantage...

In practice it seems more complex than that — but I have experienced a softer version of that idea in practice with my own work. Performance does matter, but it isn’t the only factor.

Unfortunately, you lose that advantage because in days of yore, people knew the implementation details of their hardware, and would optimize around that. With microcode. and the sheer size of certain instruction sets, it is very difficult to do the same thing, particularly mow that the philosophy of programming/computing has shifted to accomodate the industry as an omnipresent actor in your execution environment, and furthermore one with even more rights to observable machine state than you, the owner of the damn thing.

Your point on inefficient code stands, but there is far more at play than mere "programmers aren't skilled enough" and "imagine the possibilities!"

I'll wager a true Mel would not be an easy thing to reoccur nowadays.

http://www.catb.org/jargon/html/story-of-mel.html

Wingsuits are much closer to gliders than rocks aerodynamically. They can generate lift and fly upwards for a short time. Ram air wingsuits have only been around for less than 25 years but have developed dramatically during that time, even without power. They are amazing gliding craft.

Quadcopters also usually have terribly autonomy. Gliding is a lot more efficient at conserving energy so there's still a lot good engineering to be had in aerodynamics whenever you need to be in the air for more than a handful of minutes at a time.

That's why if you look at professional drones you generally only see quadcopters when being able to hover and/or execute very precise motions is required, for the rest wings are still generally superior.

It seems to me like there's a good future for electric VTOL. Whether for package delivery or for carrying people, you can take off vertically, and then transition to a horizontal flight regime using wings that's more energy efficient, so you can get more range.

This feels like the golden path to me, too. Lilium is claiming 300km range at 300km/hour, and appears to transition nicely to horizontal flight. Maybe not a great glide ratio on those stubby little wings, but it looks safer than quadcopters. They don't need all 36 ducted fans for normal flight, so eating a bird shouldn't spell death.

Has anybody else shown off similar craft? Uber Air's eVTOL looks about 50% CGI/50% hype, but maybe I've missed something.

My layman's aerodynamic hunch says that Lilium is on the right design track for practical, reliable, long-range electric VTOL aircraft.

There's two critical ingredients: Transitioning out of powered lift immediately after takeoff, and having a battery mass fraction that's as high as possible. Obviously, VTOL & payload limits the latter.

Multicopter designs won't work; their power requirements are too high.

That's what they're hoping for at Joby Aviation: https://www.jobyaviation.com/

I fly FPV drones and can confirm the propellers and motor technology has come quite far. Not to mention the leaps and bounds of flight controllers in the last few years. There seems to increasingly few things that can go wrong with my drone. Bent prop/motor shaft; no problem. Missing parts of propellers; you can still fly home. Its aerodynamics, materials and software... and most of those things are off the shelf, just an afterthought for the drone builder and pilot. Its cool to be able to shift focus to flying but agree heavily its a different craft now.

This reminds me of various videos I've seen where people strap the guts of a quadcopter to various lightweight things to make them fly (the most recent being the Corridor Crew video on making a flying Nerf gun), and they just...work. (With much shorter battery life.) Of course, that's almost entirely thanks to the control electronics - that sort of active stabilization enables almost anything to fly. You couldn't do the same thing with a passively-stable R/C airplane, for example (speaking from experience).

What is the difference between what you are describing and a helicopter? Obviously comparing quad drones to fixed wing aircraft is going to make it seem that the quad drones thrown out 100 years of innovation and theory, but they are very different things.