My Octocopter Project!

[Uncle Manuel]

None. Multi-rotors are not safe for manned flight. Period.

Tell that to companies like Volocopter...

Oh man, this thread brings back memories! I had a buddy who 10 years ago made his scratch build octocopter with laminated carbon fabric to carry a full size DSLR for aerial photography. Back then the whole multirotor thing was just getting started and there were no commercial consumer quads available, just kits and few control boards...

 

[ChrisOlson]

Tell that to companies like Volocopter..

I don't need to convince Volocopter. Volocopter needs to convince the civil aviation authorities. Otherwise, no Type Certification, no flying it allowed except under controlled experimental, or unmanned, conditions. And it's pretty simple, basically. The Volocopter aircraft meets none of the Type Cert requirements for manned rotary wing aircraft. They will likely only get approval to fly it in countries with rather poor aviation safety records like India or Korea.

 

[rockyboy]

Full Scale Multirotor Receives Experimental Airworthiness Certificate from the FAA

After 78 years, the helicopter has been reinvented. SureFly is a personal full-scale helicopter/VTOL aircraft designed for safe and easy flight.

- By Jim T. | Jan 19, 2018, 12:03 PM

https://www.rcgroups.com/forums/sho...mental-Airworthiness-Certificate-from-the-FAA

 

[cranialrectosis]

I think I would want to stack the rotors.

Just my un-tested opinion, but I would think that 4 booms with 4 areas for spinning props would be simpler and safer than 8.

I think it would also be easier to board and off-load.

Just my 2 cents.

 

[ChrisOlson]

After 78 years, the helicopter has been reinvented. SureFly is a personal full-scale helicopter/VTOL aircraft designed for safe and easy flight.

An experimental is not a Type Certificated aircraft
https://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/experiment/

And the helicopter has not been re-invented. It has taken a huge step backwards. When you add up all the blade tip losses of a multi, losses in multiple drives, and losses in rotor disc solidity, they are not even close to the power efficiency of a regular helicopter. There's a big love affair with multi's because of market hype. But re-writing the laws of aerodynamics and power systems engineering is not going to happen.

Multi-rotors have several problems with aerodynamics:
1) they have to maintain significant throttle "overhead" for stability control. Helicopters do not - they can be operated at maximum collective pitch range and still maintain full roll and pitch control with the cyclic - important for operating at the edge of the aircraft's performance envelope at maximum payload in turbulence, etc..

2) multi-rotors are most efficient in hover, least efficient in forward flight. Helicopters are the other way around and enter translational lift like an airplane with forward airspeed. Even the handling of a helicopter is the same as an airplane in forward flight, short of collective management. Multi's depend totally on frame tilt angle and differential thrust to maneuver.

It has to do with the fact that kinetic energy is given by 1/2mv^2. It takes four times more energy to move a mass of air at twice the speed, compared to only twice the amount of energy to move twice the mass of air. In both cases, the same amount of momentum is conferred (m*v). And you must displace air equal in mass to the mass of the aircraft to become airborne. So the helicopter moving a mass of air at slow speed with a single large rotor is simply more efficient than moving the same mass at high speed with multiple rotors with higher disc loading.

3) To get Type Certification, demonstration of maneuverability, control, and landing, without power, must be done. Even the largest multi-engine airliners must demonstrate it. It is why airliners are equipped with emergency ram-air turbines (RAT) for hydraulic and electrical power for the flight systems. This is impossible to do with multi-rotor fixed pitch designs. Parachute emergency landing does not meet Type Cert requirements.

So while the market hype will continue and breed a lot of crazy schemes, the basic laws of manned flight and aerodynamics are set in stone. You can get a Russian-built Micron coaxial, or a US-built Mosquito helicopter, and enjoy manned flight safely, and with quite high performance for an ultralight aircraft. I looked over the Micron at Heli Russia 2016 when it debuted and I am quite impressed with it. It is a much more robust design than the Mosquito, IMO, which I have flown quite a few hours.

 

[rockyboy]

An experimental is not a Type Certificated aircraft
https://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/experiment/

And the helicopter has not been re-invented. It has taken a huge step backwards. When you add up all the blade tip losses of a multi, losses in multiple drives, and losses in rotor disc solidity, they are not even close to the power efficiency of a regular helicopter. There's a big love affair with multi's because of market hype. But re-writing the laws of aerodynamics and power systems engineering is not going to happen.

Completely agree this isn't anywhere near a safety level where I'd want to see it in wide use. And it's a ton of marketing hype. But so was heavier than air flight at one point. And then rotary wing flight. And then supersonic. And then space flight. We come up against barriers that experts say can't be overcome, and then with years of work and research and experimentation, we overcome those barriers. And yes there are some weird miss-steps along the way, but given a long enough horizon engineering problems are overcome.

 

[WERA22]

Anybody who thinks there is going to be anything resembling an FAA Part 23 certification for a multirotor is just ignorant of the process. It is not going to happen.

Bell has been trying to certify a tiltrotor for a LONG time. I'm guessing at least 20 years. As far as I know there is still no set in stone standard for them to meet, much less have they proved they can meet it.

 

[ChrisOlson]

And yes there are some weird miss-steps along the way, but given a long enough horizon engineering problems are overcome.

Ah, but consider something here. Multi-rotors are not a new concept. They were the first designs tried in the evolution of the helicopter, and they were not then, and not now, aerodynamically stable.

The one and ONLY thing that made them popular with hobbiests is the advancment of cheap electronics to stabilize them. So suddenly people who know nothing about aviation, how to build a proper airframe, or even how to fly, can buy, build and fly mechanically simple devices and let the electronics fly it for them. Enter in marketing, lots of hype, the availability of relatively cheap lithium batteries and you have the drone industry.

And you have people that do not know better now coming up with totally crazy schemes, thinking the multi-rotor drone is a helicopter "advancement". In contrast, helicopters are inherently very stable machines. They do not need electronics to stabilize them. They are proven over better than 70 years and millions of flight hours doing things no other aircraft can do, from air ambulance to heavy-lift sky cranes.

Many people don't know it, but you can put the same autopilots used in multi-rotor drones in a RC helicopter. And the helicopter literally kicks a multi-rotor's butt for flight time, performance, sustained cruise speed, stability, and ability to handle wind. This is one of my commercially-flown helicopters with an autpilot in it, and note the absolute superb stability and smoothness with solid-mounted cameras - no gimbals or vibration isolation required for a helicopter

The difference between doing it with a helicopter vs bolting a couple sticks in an "X" and strapping on some motors, props and an electronic controller, is that you have to know what you're doing to do it with a helicopter. Interfacing an autopilot with the helicopter's controls and setting it up mechanically and tuning it is not exceedingly simple. And you have to have extensive helicopter experience either with RC or the real thing to do it. So it is far beyond the scope of the average "joe or jane" that flies multi-rotor drones because the attraction of those is "anybody can do it". But that does NOT make them suitable for manned flight. Flying anything with people in it has long involved lots of training, certifications and standards that must be met. It is not like driving a car or flying your multicopter "drone", and never will be.

 

[rockyboy]

I agreed with everything you said till this part;

It is not like driving a car or flying your multicopter "drone", and never will be.

This is where the adage comes in "When an expert tells you something is possible, they are almost certainly right. When an expert tells you something is impossible, they are almost certainly wrong." It isn't safe yet, it isn't cost/energy efficient yet, but with experimentation, research, and advances in technology that are always happening, is most certainly could be. After all, we have electric self-driving cars now - and loads of experts over the last 50 years saying it could never happen.

So rather than try and shut down a person who wants to experiment and learn, how about we all provide them constructive information and safety warnings instead of telling them it's impossible.

 

[RMDC]

Certainly, I'd like to do everything we can to remove the pilot for commuter vehicles as a factor except in the unique case of operating a vehicle for recreational purposes. Human-operated, crewed multirotors aren't feasible? Sounds great! Let's make it autopiloted and give it enough redundancy to survive some failures. After all, that's what self-driving cars are doing. Will there be failures that result in injury and death with self-driving cars? I'm sure there will. Will it be anything approaching the meat grinder of the human-operated highway? I sincerely doubt it.

 

[ChrisOlson]

So rather than try and shut down a person who wants to experiment and learn, how about we all provide them constructive information and safety warnings instead of telling them it's impossible.

There is no where I said it is impossible. It is impractical. The engineering and evolution of the helicopter as we know it today has proven it time and time again. It is quite amazing that the early helicopter designs are strangely reminiscent of what some people consider to be an "advancement" in helicopter technology.

This is a sketch of one of the early designs from the late 1800's



And another unmanned experimental design from the early 1900's



Igor Sikorsky, Art Young and Stanley Hiller were the inventors of the modern helicopter that evolved from these early designs. And Sikorsky continues to advance the design to the next level with the X2/S-97 Raider concept of compound helicopters.

I am all for somebody experimenting, trying new things. BUT - the last thing we need is to hear about is somebody that got killed putting their life in the hands of electronics that are not even CLOSE to the reliability standards for manned aviation, flying an aircraft that cannot fly without them. I get a big laugh out of outfits like Volocopter claiming redundant everything, when fuel onboard ANY aircraft is a finite thing. I've been in aviation for almost 40 years as a commercial pilot and some of these schemes I see are just plain nuts.

So if you really want to invent something, invent a redundant flight control system that can land a multi-rotor with no power. It might help reduce the insurance rates for Part 107 drones, that have skyrocketed due to property damage claims because they fall out of the sky all the time and hit stuff. Unmanned multi's already have a bad reliability and safety record and are under scrutiny by lawmakers restricting them. Maybe consider working on that first.

 

[VolksRocket]

Thread Focus

Hi,

Great conversation, but I want to keep it to solving the issues to actually do this, it is going to happen. We understand all the philosophical and ideological issues, but we are here to solve the technical issues. If it splats will load another monkey and try again!

Flying in the air in ANY vehicle, has it's risks, and we accept them.

This vehicle requires NO certification because it will be in the "experimental" ultralight category.

We are just seeking the "safest" way to do it! Can't do it, is NOT part of the equation.

What we are doing here is NOT rocket science, and I am a rocket scientist, I am seeking knowledge and input so we can build the wheel better and "safer" if possible. RPVs (Remotely Piloted Vehicles) are a HUGH market for the future, and PAVs (Personal Air Vehicles) are a HUGH market for the future also.

Let's not get bogged down in ideology, let's solve the issues!

So which layout would be the "safest", most practical for use, and redundancy of performance and maintenance, and engine out survivability, and programming? Again, we are going to use either: (1) Octo Straight, (2) Octo +, or (3) Octo x.

Please provide your choice and why.........if you want!

Sincerely and Respectfully,
Terry W. Wheelock

 

[cranialrectosis]

I would add the 4 boom coaxial config.

At the least, I think it would be easier to board.

 

[jhitesma]

So which layout would be the "safest", most practical for use, and redundancy of performance and maintenance, and engine out survivability, and programming? Again, we are going to use either: (1) Octo Straight, (2) Octo +, or (3) Octo x.

Doesn't matter. They're all the same in those respects. Just whatever is mechanically easiest for you to physically build.

A better question would be whether coaxial motors in a quad configuration or a discrete octo layout is better.

I'm not saying it can't be done...but will suggest that maybe more experience and research is in order before you get too much further. It sounds like you're trying to re-invent a couple of wheels along the way and may not be spending your energy in the most useful way.

 

[VolksRocket]

We have evaluated that.

I would add the 4 boom coaxial config.

At the least, I think it would be easier to board.

Hi,

Yes that configuration was researched and was found that the engines will not be running during boarding, and if an engine out or FOD failure occurs it possess more danger, then eight overhead engine placement.

 

[VolksRocket]

Doesn't matter. They're all the same in those respects. Just whatever is mechanically easiest for you to physically build.

A better question would be whether coaxial motors in a quad configuration or a discrete octo layout is better.

I'm not saying it can't be done...but will suggest that maybe more experience and research is in order before you get too much further. It sounds like you're trying to re-invent a couple of wheels along the way and may not be spending your energy in the most useful way.

Hi,

Yes, those configurations were tested and found to have a lower safety rating for engine out, engine FOD failure, engine redundancy failure. We have been working (or planning this) for over 15 years, but since now we are putting a monkey in it, we want to see if we can maximize the "safety", so we don't end up with mutilated monkey meat!

We like to use the axiom: Ok we are ready to build so what did we forget! It's always good to have another view!

 

[cranialrectosis]

Gotcha! Thanks for the update and insight.

Pop was a rocket scientist with Douglass then Northrop from the 50s into the 90s. He built an autogyro in the late 50s because PAVs were gonna be YUGE. I wish he could be here today to see how far we have come.

Please keep us posted.

 

[ChrisOlson]

Yes, those configurations were tested and found to have a lower safety rating for engine out, engine FOD failure, engine redundancy failure.

I am totally confused. What "safety rating" is this you refer to? I happen to know how these things work, inside and out. I am one of the developers on the ArduPilot project, and chief test pilot for TradHeli, being the various frame layouts you posted are direct from Mission Planner.

https://github.com/orgs/ArduPilot/people

FYI, those frame layouts have ONLY to do with the orientation of the autopilot in the frame and selecting drive rotation direction accordingly. It has nothing to do with "safety" or performance. The software is developed and maintained by a team of professional engineers and pilots, is flown by virtually every university aeronautics research dept, even Boeing and NASA flies our software. But this is the very first I have heard of a "safety rating" based on frame layout. Since I am 100% familiar with how the code that flies these things works, I would be really interested in learning more about this "safety rating".

 

[VolksRocket]

Safety Rating?

I am totally confused. What "safety rating" is this you refer to? I happen to know how these things work, inside and out. I am one of the developers on the ArduPilot project, and chief test pilot for TradHeli, being the various frame layouts you posted are direct from Mission Planner.

https://github.com/orgs/ArduPilot/people

FYI, those frame layouts have ONLY to do with the orientation of the autopilot in the frame and selecting drive rotation direction accordingly. It has nothing to do with "safety" or performance. The software is developed and maintained by a team of professional engineers and pilots, is flown by virtually every university aeronautics research dept, even Boeing and NASA flies our software. But this is the very first I have heard of a "safety rating" based on frame layout. Since I am 100% familiar with how the code that flies these things works, I would be really interested in learning more about this "safety rating".

Hi,

Nope, it is a simple screen shot capture to illustrate the layouts we are discussing, which has to do with frame layout, motor direction, flight controller orientation, programming configuration, visual layout, maintenance feasibility, engine out recovery, FOD engine failure survivability, redundancy ability, flight stabilization in manual, auto-stabilized, and autonomous flight mode, which all result in a "Safety Rating" that is based on General Aviation Safety Standards as to which layout would be best to use after weighing all the criteria to put a monkey in this thing.

We realize what we are doing is ahead of and beyond the available "consumer" flight controllers, educational research, as is with the ArduPilot Project. Again, you maybe assuming to much. We are just building a "personal air vehicle", that can be built in your garage, and by the average person. We are working with real world design, building, testing, and application, not educational theory.

I guess we are ahead in exploring, testing, and setting the standards for the "Minimum Safety Rating" of a PAV. Again, we have tested ALL conceivable configurations, we are just asking for people's views, maybe they see or know something we haven't looked at already. Remember what we are doing here ain't Rocket Science.

So again, which layout do you believe would be the best layout (of the three we have put forth)?

 

[VolksRocket]

The Dream!

Gotcha! Thanks for the update and insight.

Pop was a rocket scientist with Douglass then Northrop from the 50s into the 90s. He built an autogyro in the late 50s because PAVs were gonna be YUGE. I wish he could be here today to see how far we have come.

Please keep us posted.

Cool, yep sounds like Pop had the dream that one day there would be a vehicle you could roll out of the garage, get in, push the buttons and tell it where to take you, and then have coffee and read the paper on the way! Beyond the Jetsons! We have that dream too, and believe we can (or are gonna try) to take us a step closer! Hell, they promised us "HOVERCARS" back in the 50s, where they crap are they! Don't even get me started with MOLLER!

We will keep you posted! And you have to vote on which layout (of the three layouts) you think we should use?