Eli5: what are the benefits of a normal helicopter design vs a quadcopter we see on drones?
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In addition to what else was said here.. a single engine/motor failure on a quadcopter is not recoverable while an engine failure on a helicopter can result in a safe descent via autorotation.
The company Joby is scaling up what is essentially an electric quadcopter. The rotors pivot to face forward when traveling.
Not knowing very much about helicopters, though I do know some about product design.
Generally you want to go by the keep it simple principle, having 4 rotors means you need 4x everything, engines, steering, rotors, etc. Also you need a system which will be very complex to ensure everything is working together.
There’s is no need to 4x all of your costs to your entire supply chain, not to mention huge amounts of time spend on research and development if the current way a helicopter works, works well enough for all required use cases.
There also seems to be a common case where combustion engines is involved. Usually you want 1 engine moving as much stuff as possible. It’s the same reason we use 1 truck and not 4 vans, 1 container ship and not 600 boats, 1 train with 20 carts. It’s just way more efficient.
Though I guess there could be a case where there is a niche requirement for a quad copter, because of faster steering, stability or whatever they do really well. In that case there would be an argument for it, if the requirement deems it worth the effort. Though in niche areas, it’s probably much cheaper just using 3 helicopters hoping one succeeds rather than reinventing a helicopter.
I feel like something everyone is missing here is that the OPs question seems like a question of design, rather than a question of current practical implementation. One user commented about autorotation being missing from current drones, but didn’t consider adding it to hypothetical quadcopters and seeing if they are still as safe or unsafe.
So the question could be, and is possibly still unanswered: assuming each style (quadcopter and single-with-tail) has all of the general technology benefits of the other style (having rotors on a quadcopter, for example), what are the inherent benefits of the heli styles single-with-tail versus the quadcopter style, for the same payload capacity?
My first thought, is that two motors is less expensive than four motors. The takeoff/landing ground area is smaller. What else?
No, it’s not, that’s why I said faking it. It’s a way to allow the craft to land safely using rotation, but obviously working on a completely different principal. The only reason they even get mentioned together is that was the original inspiration for why they explored using rotation to assist. I only know that because I know one of the people who originally developed it. Like you said, they quickly figured out it wouldn’t make sense to use the same principal.
quad-coptors (drones) require instant torque in order to make the microsecond corrections that they need to make every microsecond to stay afloat. You need electric engines to do that – combustion engines have to rev up to produce torque.
However, batteries are *WAY* less energy dense than gasoline is, so in order to have a drone as big as a helicopter, you’d need a prohibitively heavy amount of batteries.
Significant benefit of an RC helicopter vs. quad-rotor drone – both using lithium-polymer battery for driving an electric motor(s) is it’s more quiet – longer blades spinning more slowly mean a lower frequency sound which is also much more difficult to locate vs. high pitch sound.
RC helicopter vs. conventional quad-rotor drone is significantly more agile/maneuverable. For example, can fly inverted. If your exposure to drone flight is via DRL, watch YouTube videos of RC helis – watch this – [https://www.youtube.com/watch?v=QSiwyoQldfo](https://www.youtube.com/watch?v=QSiwyoQldfo) – but this machine is set up for absolute performance. Set up for lower rotor head speed and the model is not as agile but is much more silent/stealthy.
Helicopter needs a tail rotor and the blades of the main rotor have to be articulated – they have to change pitch as the blade goes around the circle to allow the helicopter to hover or fly forward or to sides. This mechanism is very complicated and very expensive.
With quadcopter you need four rotors with fixed pitch – basically normal propellers run by four motors. You then simply control the rotation of individual motors through electronics. MUCH simpler construction.
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what are the benefits of a normal helicopter design vs a quadcopter we see on drones?
There are many benefits to a traditional helicopter design over a quadcopter drone. Some of these benefits include:
– Helicopters can fly in all directions, whereas quadcopters can only fly forwards, backwards, left, and right.
– Helicopters can hover in one spot, whereas quadcopters cannot.
– Helicopters can fly at much higher altitudes than quadcopters.
– Helicopters can carry much heavier payloads than quadcopters.
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