Question about Licensing
 

Hi

Immagine you build a prototype of an Helicopter, and you want to test this for real, so after all the sizing and engineering and simulation, you actually built a real scale prototype of this thing and want to fly it using an RC control.

Does one need a special authorization to do this...?

Even considering that you will be doing it far away from any city or urban settlement... ?

I am talking of a contraption weighing about 790 kg, with a co-axial rotor with a span of 8m...


BRGDS

Alex

before of paper work that may depend on your country you may just want to make all security precautions. If ok, than you can do some basic test for research purposes.
You basically need authoritzation/company to develop helicopters but if it's just homebrew than maybe you can do it as long as noone complains;)

It is not my company's... If it were, all the bureaucratic infrastructure would already be setup...

It is my thing...

I designed it, sized it, bought an engine for it, validated it with simulation tools, all OSS, only used a company's proprietary app to create some piece geometry specs for the CNC milling, mainly the rotor assembly, where precision specs/surface finishes are more stringent because of fatigue failure probs... and I am now in the process of assembling the thing...

But I am just too chicken to sit in the pilot's seat in it's maiden flight... so I will probably RC the thing to take off, and test it while staying in ground.

800kg. That's about as much as a Robinson R44 (alternative post-flight configuration) or the bull that got granny weighs. Since the R44 equivalent has a 183 kW powerplant, which should be enough power to dig a nice hole in any close by Karesansui garden, I'd contact the Japan Transport Safety Board.

What happened to that old kamikaze spirit? Get in it and fly!!! :)

Remote controlling it will add a whole new dimension to the experience - and I am not suggesting that as a good thing. You'll increase your complexity and even if you are a fully qualified helicopter pilot, you won't be able to automatically fly the RC version; controls are too different and your inputs are too different.

You'll probably crash it if you try it that way unless you make truly extensive preparations (including learning to fly an RC helicopter). For reference, I DO fly RC aircraft (including helicopters), and I used to fly full-sized fixed wing; it is very different from a kinaesthesia standpoint.

As for regulations: I have no idea about regulations in Japan governing use of the RF spectrum, but I'd bet there are laws on the books pertaining to remotely controlled aircraft above a certain weight.

Hi BrianL

There was much Honor and Love in dying to try to save the ones a person loves from Hardship... this is why Japanese Pilots in WW2 resorted to Kamikaze attacks when War economics no longer supported a "normal" operating navy air force or army air force with all of its logistics problems ( air force was not an indpendent arm in the Empire of Japan ), like fuelling, maintenance, replacement aircraft, scarcity of materials... etc.

Piloting my "yet wannabe" helicopter and dying in it would not be honourable... It would nonetheless be a testimony of my "courage" and confidence in my Engineering Skills, and to boil this down, a testimony of my Ignorance of what Helicopter design is really about... :)

Many "hard bearded" engineers all over the world have made gross mistakes when designing aircraft, bridges, warships, etc...

... It is a bit of an "unfair fight" trying to design something to operate in an environment out of which you KNOW nothing... you design based on estimations of the reality not on a reality which you do not access that's why Engineers use safety factors... Physicists do not...

BRGDS

Alex

Hi jiml8

Is there no RC control system with Haptic feedback on actuator forces...?

Some sort of "Hydraulic feedback servomechanism" relayed through the data channel of an RC...?

... even if this exists, must be overly expensive...

Is it difficult to fly an RC chopper...?

BRGDS

Alex

I am aware of no such mechanism. The military incorporates such devices in full-motion simulators, but I know of no commercial products that do it.

RC helicopters are generally difficult to fly, though it has gotten easier as gyroscopic technologies for use onboard with negative feedback for stabilization has matured. The gyro will make the machine neutrally stable, which greatly simplifies the learning curve. However, consider that you'll be operating a full collective rotor head, with tail rotor yaw control with no feedback other than visual, and you figure it out. It isn't easy.

RC helicopter masters can perform amazing acrobatics with their machines, so it certainly can be done.

Hi

I do not use Tail rotor yaw control, I get yaw control from relative torque magnitudes of the two main rotors in my co-axial bi-rotor... a bit more complex mechanically speaking, but less so dynamically speaking... :

I decouple the reactive pitch torque from tail rotor speed variation from yaw control... In "conventional" helis, yaw control introduces pitch changes...

That will be slow. What kind of yaw rate do you expect to achieve?

Complicated transmission too.

Hi,

Building an active physical model aka prototype vs computer model is jumping some design levels. Prove the design. I would use a small scale prototype to prove the functionality & design validity. For one it's cheaper let alone safe. Tether control could be used to prove and provide the means for instrumentation testing.

If your prototype does prove to be practical via experimentation for the systems then proceed to the flight stage. Hopefully you can test things without damage or hazardous situations.

Here in the U.S. we have several areas that are used for active testing. Restricted land & air space for both private and military usage. Land & air space availability for such testing in Japan would be limited.

Hi

My Yaw PID controller has a saturation at +-12º/s... The structure has been designed to resist to +-30º/s in Yaw...

This is Slow... It is not a Kamov-50 I'm designing here... :)

BTW... Kamov claims Yaw rates of +- 30º/s... and they use co-axials too... how do they do it...?

Why is it that American combat helicopters never used Co-axial rotor technology...? Lesser availability/reliability ( more complex transmission ) in combat scenarios ? The dynamics is not as "Entangled" as with the Tail rotor control... has no Lift assymetry... better hover charateristics... what are the probs of Co-Axials besides of maintenance/reliability...?

The Kamov's are splendid war machines... IMHO


BRGDS

Alex

This is easier to fly, and to build than a full featured Helicopter... :)

http://www.youtube.com/watch?v=_EFt7cLCRSY

And this can reach greater speeds than any Heli... ( Excepting Sychropters probably... )

Coaxial technologies have been explored at least as far back as the early 1930s using counter-rotating coaxial propellers on airplanes. Technology never caught on here. I'm not really sure why; we've been unafraid of complexity on many other systems (notably the F-35 with its wind turbine system) and there are a lot of efficiency and performance advantages to counter-rotating coaxial rotors.

I personally have done work on US Navy helicopter systems where vibrations from the tail rotor system were causing some massive headaches for a critical avionics suite. The problems would have vanished if the platform had been tail-rotorless.