Drones and Helicopters - How do they compare

[voyagerB]

Hi guys, here's my maiden posting. I hope that I will not offend anybody here, since this is a helicopter forum.

 

My question is: How do multi-rotor aerial vehicles or drones compare to helicopters in terms of performance?

 

Let me elaborate. I know the basics of helicopters: ability to adjust the rotor to optimize lift and efficiency, auto-rotate to the ground in case of an engine failure. What I am interested in is in comparision figures with regard to:

 

1. How big does a rotor system of a drone need to be to have the same lifting power of a comparable helicopter? Quad or Hexa configuration (four or six thrusters)?
2. Diameter of the individual rotors? How many blades would be ideal? Let’s compare this to the cheapest choppers around, the Robinson R22. It uses a Lycoming 130 hp 320 Nm 5.2 liter 4-cyl. that’s able to lift 620 kg. Main rotor diameter 7.67 meters. Sorry for the metrics.
3. If the multi-rotor aerial vehicle uses hybrid electric drive, what will be the required ‘oomph’ to get the same 620 kg off the ground?

My interest of course is manned VTOL vehicles other than helicopters. Thx.

[avbug]

You may want to pick up a degree in aeronautical engineering. It will help you in your search. Your questions will require one.

 

This is not the domain of pilot training.

[Astro]

Buy this guy a bottle of vodka and maybe he'll share some tidbits with you?

 

 

https://youtu.be/JkIc2Y5gKYM

[crashed_05]

I cannot answer your exact questions, but in many cases, manned helicopters are being converted to unmanned or optionally piloted aircraft. The newer MQ-8C used by the Navy is a Bell 407 converted to an unmanned machine. The K-MAX is another manned helicopter made into a a remotely-piloted aircraft. These aircraft are capable of lifting just as much or more than their manned versions (weight of pilot replaced with more fuel or more cargo/payload) and completely capable of selecting a clear landing zone all on their own.

 

<iframe width="560" height="315" src="https://www.youtube.com/embed/FzqMeAaOIYI"frameborder="0" allowfullscreen></iframe>

 

<iframe width="560" height="315" src="https://www.youtube.com/embed/AaG2EDPVBqc"frameborder="0" allowfullscreen></iframe>

[voyagerB]

Sometimes the possibilities suggested seem 'massive'. Like this DARPA project:

 

[Wally]

Hi guys, here's my maiden posting. I hope that I will not offend anybody here, since this is a helicopter forum.

 

My question is: How do multi-rotor aerial vehicles or drones compare to helicopters in terms of performance?

 

Let me elaborate. I know the basics of helicopters: ability to adjust the rotor to optimize lift and efficiency, auto-rotate to the ground in case of an engine failure. What I am interested in is in comparision figures with regard to:

 

1. How big does a rotor system of a drone need to be to have the same lifting power of a comparable helicopter? Quad or Hexa configuration (four or six thrusters)?
2. Diameter of the individual rotors? How many blades would be ideal? Let’s compare this to the cheapest choppers around, the Robinson R22. It uses a Lycoming 130 hp 320 Nm 5.2 liter 4-cyl. that’s able to lift 620 kg. Main rotor diameter 7.67 meters. Sorry for the metrics.
3. If the multi-rotor aerial vehicle uses hybrid electric drive, what will be the required ‘oomph’ to get the same 620 kg off the ground?

My interest of course is manned VTOL vehicles other than helicopters. Thx.

 

 

Having had a couple of exciting events in my life as a pilot as a result of failures of structure and drive train issues, I am Horrified at the idea of relying on more than two rotors to fly, much less survive. The power systems are redundant, the failures are unlikely, blah blah blah. I assure you that at least three failures I survived were highly improbable, especially compared with having 4, 6, 8 or more rotors to operate harmoniously. Even two lifting rotors introduce failure modes that increase risk,,,

[voyagerB]

 

Having had a couple of exciting events in my life as a pilot as a result of failures of structure and drive train issues, I am Horrified at the idea of relying on more than two rotors to fly, much less survive. The power systems are redundant, the failures are unlikely, blah blah blah. I assure you that at least three failures I survived were highly improbable, especially compared with having 4, 6, 8 or more rotors to operate harmoniously. Even two lifting rotors introduce failure modes that increase risk,,,

 

The whole idea is that manned drones shouldn't be piloted in the sense of needing training and a license to keep your balance up in the air, but flown autonomously like the unmanned camera drones that have flight stabilisation systems. Obviously, the failure of a single motor would tip a quadcopter (four thrusters) off balance. A hexacopter (6 thrusters) however may well stay in the air long enough for a safe landing. They throw tanks out of a plane hanging from a chute. I guess that you can expect the same thing with multi-rotor drones to prevent them from falling from the sky.

[Guest pokey]

.

 

This is not the domain of pilot training.

 

The main title of this section of the forum is: "General Helicopter Forum

Post messages about ANYTHING relating to helicopters!" SO? this if perfectly legitimate question for this section.

 

I cannot answer your exact questions, but in many cases, manned helicopters are being converted to unmanned or optionally piloted aircraft. The newer MQ-8C used by the Navy is a Bell 407 converted to an unmanned machine. The K-MAX is another manned helicopter made into a a remotely-piloted aircraft. These aircraft are capable of lifting just as much or more than their manned versions (weight of pilot replaced with more fuel or more cargo/payload) and completely capable of selecting a clear landing zone all on their own.

 

 

 

And don't forget Schweizer's UAV ! This was the reason Sikorsky bought the company. (oh right, the real reason was sickhorsey wanted to get into the light helicopter flight training business)

[SBuzzkill]

This article should answer all your questions.

 

https://www.forbes.com/sites/quora/2013/12/23/what-makes-the-quadcopter-design-so-great-for-small-drones/#73021dd8654f

 

I just want to highlight:

 

 

 

So there you have it: quadcopters are mechanically simpler (therefore potentially cheaper), but not necessarily any more stable, and definitely less efficient than conventional helicopters. And because the mechanical simplicity becomes less of a benefit as you increase the size, while the inefficiency becomes more of a hindrance, they do not scale well, and are not used for large-scale transport (and probably will never be used for large-scale transport).

Edited May 8, 2017 by SBuzzkill

[voyagerB]

This article should answer all your questions.

 

https://www.forbes.com/sites/quora/2013/12/23/what-makes-the-quadcopter-design-so-great-for-small-drones/#73021dd8654f

 

I just want to highlight:

 

Thanks. I have read that. But experts seem to disagree on the inefficiency. Generally, a fixed-pitch propeller (FPP) is both cheaper and more robust than a VPP. Also, an FPP is typically more efficient than a VPP for a single specific rotational speed and load condition... I guess that still a lot needs developing in terms of fixed-pitch rotor designs. The biggest problem will be in generating enough 'oomph' from the electric motors and having adequate range. The basic simplicity of multi-rotor designs is too good not to upscale them from carrying cameras to carrying people.

[chris pochari]

https://aviation.stackexchange.com/questions/3300/why-havent-quadcopters-been-scaled-up-yet Here is your answer. Stack Exchange vs Vertical Reference!

[voyagerB]

https://aviation.stackexchange.com/questions/3300/why-havent-quadcopters-been-scaled-up-yet Here is your answer. Stack Exchange vs Vertical Reference!

Thanks. Of course, I had been reading that one too. What I noticed, however, is that all new initiatives with regard to next-gen VTOL craft are based on fixed-pitch propellers... Must tell something.

[chris pochari]

Thanks. Of course, I had been reading that one too. What I noticed, however, is that all new initiatives with regard to next-gen VTOL craft are based on fixed-pitch propellers... Must tell something.

The V22 is not a fixed pitch propeller tho

[voyagerB]

The V22 is not a fixed pitch propeller tho

I know. But Osprey prototyping dates from the 80's. And it's ICE propelled. Paramount about using FPP is using electric drive.

[chris pochari]

I know. But Osprey prototyping dates from the 80's. And it's ICE propelled. Paramount about using FPP is using electric drive.

What's your take on the AW609?

[voyagerB]

What's your take on the AW609?

Both were Bell developments. Both beautiful designs. I mean, what's not to like about a craft that is both: airplane and chopper. Bell was taken over by AgustaWestland. It says (on wikipedia) that AgustaWestland estimated a market of 700 aircraft over 20 years. Doesn't seem that much. The propellers are of the variable pitch kind (of course).

[Guest pokey]

tilt rotors, WHY?,, then again: whynot?

Like Mt Everest: "because its there"

space exploration: "because its a challenge"

the 6 million $$ man: "because we have the technology"

ice cream: "YUM"

 

My opinion (which don't add up to a small hill of beans), is that the tilt rotor really has no future-anywhere. It can't do all that either an airplane nor a helicopter can do, it takes the best of both?-yes. But also the worst. It's a bit like owning a boat, why? well, its a deep hole to dump $$ into. Plus? gets me out of the house on the weekends and golf is boring. The space shuttle and the Concorde were great achievements too, but where are they now?

 

Don't get me wrong, i'm all for progress, new stuff needs to be tried, developed & then scrapped.

[Wally]

Tilt rotors are less efficient than both airplanes and pure helicopters.

[avbug]

 

They throw tanks out of a plane hanging from a chute. I guess that you can expect the same thing with multi-rotor drones to prevent them from falling from the sky.

 

 

Huh?

 

Are you suggesting using parachutes to solve deficiencies in helicopter or rotor operations?

 

Are you comparing parachute extracted drops from fixed wing aircraft to deploying a parachute from a rotorcraft? What's your point?

 

Also, an FPP is typically more efficient than a VPP for a single specific rotational speed and load condition...

 

Absolutely untrue.

 

Angle of attack at any given point on the propeller (or rotor) is dependent not only on rotational speed, but airspeed and the angle of operation in relation to the relative airstream. In a fixed wing aircraft, propeller efficiency is a significant variable with airspeed, and more so with pitch angle which can vary considerably with airspeed. It's for this reason that on most counterclockwise turning fixed wing propellers, considerably more right rudder is required in slow flight. Fixed wing propellers are never more efficient than variable pitch propellers

 

To apply the concept to rotorcraft, the concept of a fixed wing propeller is tantamount to eliminating the collective.

[Hand_Grenade_Pilot]

'Drone-type' aircraft are too inefficient when scaled up; specifically, too low of a useful load and too slow. Combine that with a mechanically complex design and it ends up being more trouble than its worth.

 

Compound helicopters (such as the Sikorsky X2) are the next logical step. While the design will initially be cost prohibtive for civilian application, it will make an excellent platform for VIP transport, EMS and deep water O&G operations when the technology becomes more affordable.

[Guest pokey]

Ballistic chutes are common on ultralites. Also doesn't Cirrus have a parachute system too?

 

Don't most single engine airplane propellers rotate 'clockwise' (the ones built on this side of the pond anyhow) & the reason for right rudder/high climb angle is P-factor. On ccw, that would be left rudder.

 

The toy model drones use FFP and vary the electric motor speed, thus eliminating all them moving parts. Would take detailed analysis to compare that type of thrust variation to that of VPP. I'm sure on the 'net it could be found, but? i'm not all that interested in it to do any research.

[r22butters]

How do they compare?

 

The future for drones is bright!

 

The future for helicopters is getting dimmer and dimmer and dimmer,...?

 

[Guest pokey]

i hate to bring this topic up, especially to a man like butters. But? what are the odds of your toast falling butter side down?

 

i just realized that it may be taken in the wrong way butters. My intention was towards "statistics" not you personally

 

butter side down is directly proportional to the last time you cleaned the floor, and if the cat is in or outside, the dog comes into play too, OK,, i think i covered most of the bases.

Edited May 11, 2017 by pokey

[r22butters]

Hmmm, well statistically I don't eat toast,...and I don't butter my bagel either, but if you're a betting man, my money is on drones!

 

I have of course always favored doom and gloom,...though I've also noticed a lot of movies these days hinting at a more dystopian future, so I guess Im not alone?

[voyagerB]

Hmmm, well statistically I don't eat toast,...and I don't butter my bagel either, but if you're a betting man, my money is on drones!

 

I have of course always favored doom and gloom,...though I've also noticed a lot of movies these days hinting at a more dystopian future, so I guess Im not alone?

 

Helicopters have their advantages. So have multi-FPP systems. The last ones still need developing whereas helicopter development (already underway since WW2) is more incremental. All (!) new ventures in manned VTOL craft focus on FPP systems.