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SureFly – a personal helicopter designed for safe and easy flight

workhorse.com

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Re: SureFly – a personal helicopter designed for safe and easy flight

#71

Post by FabHK »

SideburnsOfDoom wrote: post #2

What is the benefit of more, smaller rotor blades over fewer, larger ones? I thought that the area of air that the blades worked on scaled with pi-r-squared, which favours fewer larger rotor blades, as seen on most helicopters?

With multiple smaller rotors you control by differential speed of the rotors, which are then fixed pitch, and much simpler mechanically. Smaller (lighter) rotors allow for quicker speed adjustments.

Coaxial counterrotating rotors, as here, have two further advantages:

1. they're much more efficient, as less energy is converted into (useless) air rotation.

2. in forward flight, one side of the rotor "sees" higher relative speed, thus extra lift, while the receding side sees less lift. That's cancelled out by the counterrotating rotor above.

Generally, larger diameters are good for hover performance and better autorotation, though autorotation is not really a factor for this design.

EDIT to add: Note that the total disc size of one large rotor is of course the same as the one of 4 smaller ones with half the radius.

Re: SureFly – a personal helicopter designed for safe and easy flight

#72

Post by michaelbuckbee »

sp332 wrote: post #70
laythea wrote: post #69

Earlier quoted context omitted.

I wouldn't worry about that. Most people can't even drive cars in "2D" safely, never mind helicopters. The general public will never be given the skies, unless the flights are automated.

It's much harder to hit something in the air.

But much easier to hit something on the ground (powerlines, houses, highways).

Re: SureFly – a personal helicopter designed for safe and easy flight

#73

Post by FabHK »

bri3d wrote: post #21

Why this and not single-rotor collective pitch? There's no good explanation in the marketing material.

That's the whole point of these drone-like copters: instead of one engine and main rotor with mechanically complicated collective pitch, you have many fixed-pitch variable speed rotors sitting directly on an electric motor. The complexity thus wanders from hardware to control software.

Re: SureFly – a personal helicopter designed for safe and easy flight

#74

Post by FabHK »

neurotech1 wrote: post #30
advisedwang wrote: post #11

I'm very skeptical of their claims of "unparalleled safety". Thanks to "autorotation"[1] regular helicopters can safely land in most situations even with complete power failure. The claims of safety of this craft seems to derive from N+1 battery redundancy which isn't that impressive. They say they have 8 independent motors, but don't say how many are needed to stay aloft. [1] https://en.wikipedia.org/wiki/Autorotati…

Small "personal" helicopters like the Robinson R22 are quite difficult to autorotate safely in a real emergency, due to low rotor inertia. [0] For the SureFly, Hypothetically if loss of several motors caused the aircraft to be unable to maintain altitude, the aircraft would not suddenly drop like a brick, but drift down to a controlled landing. [0] http://philip.greenspun.com/flying/robinson-r22

> For the SureFly, Hypothetically if loss of several motors caused the aircraft to be unable to maintain altitude, the aircraft would not suddenly drop like a brick, but drift down to a controlled landing.

Source? I'd think loss of two stacked rotors would lead to loss of control, tumble, and dropping like a brick (until BRS deployed), not controlled descent and landing.

Re: SureFly – a personal helicopter designed for safe and easy flight

#77

Post by georgeecollins »

nine_k wrote: post #62
egeozcan wrote: post #46

Earlier quoted context omitted.

An average plane carries around 150 to 200 people and planes are used only for long distances. Living in a world where the affordability of these are like cars, would be far worse, I imagine.

Unlike cars, these machines would not be tightly packed into roads, concentrating the noise and pollution; likely they'd have to keep a serious distance. Also, with a top speed of 70 mph and range of 70 miles, it does not look like a great daily-commuter vehicle. This device looks like a good fit for an expensive urban fast-jump service, or a good solution for places where roads are hard to build, like going to a for…

I think there are a lot of places (SF, Los Angeles) where if you could travel 25 miles at a consistent 50 MPH speed that would be a huge improvement over many people's commute. It would be great for my commute personally. I can see reasons why this would not work as a commuter vehicle, but speed and range don't seem to be the issue.

Re: SureFly – a personal helicopter designed for safe and easy flight

#78

Post by gr3yh47 »

FabHK wrote: post #74
neurotech1 wrote: post #30

Earlier quoted context omitted.

Small "personal" helicopters like the Robinson R22 are quite difficult to autorotate safely in a real emergency, due to low rotor inertia. [0] For the SureFly, Hypothetically if loss of several motors caused the aircraft to be unable to maintain altitude, the aircraft would not suddenly drop like a brick, but drift down to a controlled landing. [0] http://philip.greenspun.com/flying/robinson-r22

> For the SureFly, Hypothetically if loss of several motors caused the aircraft to be unable to maintain altitude, the aircraft would not suddenly drop like a brick, but drift down to a controlled landing. Source? I'd think loss of two stacked rotors would lead to loss of control, tumble, and dropping like a brick (until BRS deployed), not controlled descent and landing.

there's a parachute

Re: SureFly – a personal helicopter designed for safe and easy flight

#79

Post by georgeecollins »

laythea wrote: post #69
oliv__ wrote: post #19

A part of me thinks this is really cool tech and it would be amazing for anyone to be able to just hop aboard their personal helicopter and fly wherever they want, but then another part of me thinks of the future this would create, skies no longer clear, filled with objects buzzing around and what hell that would be, on top of the already stressful and crazy life we have now. It's the kind of situation where I think…

I wouldn't worry about that. Most people can't even drive cars in "2D" safely, never mind helicopters. The general public will never be given the skies, unless the flights are automated.

Don't today's drones and airplanes demonstrate that automating flying is a lot easier than automating driving?

Re: SureFly – a personal helicopter designed for safe and easy flight

#80

Post by FabHK »

_ph_ wrote: post #61

For drone-style helicopters, I find the Volocopter ( https://www.volocopter.com/de/ ) the most intriguing concept. The designers of the Volocopter took extreme care for redundancy. It can keep flying with up to 6 of the 18 rotors failing. Even the electric system and the controls have multiple redundancies. The first craft already got licensed for flying in Germany.

Much prefer the Volocopter as well. Better redundancy, further down the line (manned flights since 2016, negotiations with regulators progressing), not vapourware, more visually pleasing (though that's subjective, obviously).

In this design, I like the compactness (foldability), counterrotating rotors (for efficiency), the fact that the rotors are not in knee-height (like in this eHang 184 abomination), and the electric/fuel hybrid system.

BTW, I like PEVA as a name for this type of vehicle: Personal electric VTOL aircraft.

EDIT to add: Volocopter and eHang 184 have been around for years, and SureFly "reinvented" the helicopter? Right...

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