Fly by Light Eurocopter

[NigD]

Anyone have any details about the EC135 with the fly by light control system.

Just know that you are supposed to only have to move the cyclic. Software, a powerful computer and sh*t fast fibre optic cable data transfer take care of the pedal, collective and engine management.

If it gets ant easier, you pro pilots will have to take a pay cut:D

NigD

[MightyGem]

It will NEVER get that easy:D :D

[tecpilot]

@NigD

I've seen you are an engineer and here are now some engineers words.

EC develops that ship for the german DLR, the german aerospace center as a primarily inflight helicopter simulator. The EC 135 called ACT/FHS, Active Control Technology Demonstrator/Flying Helicopter Simulator, is a unique, advanced airborne testbed. The aim of the development project, which is commonly funded by the German Ministry of Defense, DLR, and industry, is to validate key technologies for the future generation military and civil helicopters for extending the flight operation in direction of 24h and all- weather conditions. EC 135 ACT/FHS is designed to allow the in-flight evaluation of new control technologies, cockpit designs, and man-machine interfaces in a real environment and with the pilot in the loop. A/c is a normal serial ship s/n 28 and refitted with fly-by-light technology, smart actuators, high speed processors, state-of-the-art sensors, and advanced, programmable display systems. Accordingly, the system is structured with a hierarchical architecture and consists of two associated on-board units, a core system, developed by industry, and an experimental system, developed by the DLR.
Core system:
The core system, which is a four times redundant direct link (1:1) fly-by-light control system, is designed with a 10-9 failure probability in accordance with the operational certification requirements.
It's the redundant direct link fly-by-light system, which is the primary control system for both pilots without any restrictions in the flight envelope. The main structure is composed of the quadruplex pilot input position sensors, the four-lane control signal processing computer (CSPC), and "smart" actuators for the four axes, each supplied with a four-lane actuator electronics box, which is an integral part of the actuator block and performs internally the closed loop actuator control. The CSPC is the central processing unit of the core system, where the functions for switching, fading, and blending between the modes, the signal monitoring, and the signal filtering are implemented. The CSPC is the only interface to the experimental system. In the experimental mode, the evaluation pilot’s control inputs are transferred via CSPC to the experimental flight control computer and the rotor control commands are sent to the actuators.
Experimental system:
The experimental system is designed as a simplex system and fulfills the demands of a modular multi-role system. The prospects for future system modifications and an extension of system redundancy are considered. It's designed as a fail-safe system and consists of the flight control computer, the data management computer, two multi-function displays with the graphics processors, various sensors, interfaces to the basic helicopter equipment, and the data acquisition and telemetry system. Standard type interfaces are provided to allow integration of additional components. The modularity provides the capability to easily replace or add individual components and to modify or extend the system.

The installation of side arm controllers is optional. For the pilots, the control and display units (CDU) for the core and experimental systems are integrated in the center console. The test engineer can use a multi-function display and the CDU for the experimental system, which are installed in the engineers panel. In addition, he can use quick look and experimental system management capabilities.

Not uncommon for a unique and new technology ship, EC is unfortunately behind the development schedule.
The first flight of the converted EC 135 s/n 28 , initially scheduled for 2000, took part on 28/01/02. As a precursor DLR has utilized a BO 105 "fly by wire" until the helo crashed in 1995.
The new ship will be operated by DLR and will serve as a technology testbed until about 2020.

Engines and the main parts are the same as serial.

And NigD :) it's fitted with TWO collectives and "Praise the lord, there is a future" needs human pilots (with engineering background) to leave the good ol' earth...

[Vfrpilotpb]

Hey Tecpilot,


Sorry you lost me just after the word German, but never mind I want one, where can it be had and how much warranty is with this sort of thing, can it all be retro'ed into uncle franks most popular craft,( dont want to say the number for fear of setting off the more disdainful type's):D

[NigD]

Wow. Thanks for that.

I think I'll stick to retrofitting EGPWS/TCAS/RVSM and FMSs onto older corporate jets.

My head aches trying to comprehend all the quadruple redundant systems:D

Regards

Nigd

[Lu Zuckerman]

Unless they have four separate and independent electrical systems with inter lane-switching capability they will never reach 10-9 mean time between catastrophic failure. If they did have these systems they could reach 10-9 but only on paper.

It should be noted that all commercial aircraft have a system catastrophic failure rate of 10-9 and not one has ever achieved that goal although they were certified based on paper calculations showing the attainment of that goal.




:eek:

[tecpilot]

Hey Lu,

that's the words you are famous. :cool:

"Unless they have four separate and independent electrical systems with inter lane-switching capability they will never reach 10-9 mean time between catastrophic failure. If they did have these systems they could reach 10-9 but only on paper. "


It's not necessary to told you that digits like 10-9 are important for the certification process. May be there was a time you took part on the design of such authority-regulations? :D

We have structural and fail-safe definitions on both sides of the atlantic sea. Written on papers (sometimes with blood), defined on papers, count on papers. You are working the whole day with papers? :p But that couldn't be! You are thinking about ... Respect and thumbs up!

Thanks god, there are cool men (sometimes certified as pilot AND engineer at once) to hold down the scientifics and desktop engineers to leave the earth.

Therefore on TP's wishes s/n 28 is equipped with an additionally emergency set of good ol' mechanicle controls. Initiated by clutches. Sorry forgotten to say :rolleyes: Absolutely needless, additionally costs and weight or ???????????
10-9 !!!

The ship will get only an restricted civil certification. Only to fly by a 3-man standard crew (2 TP's and 1 FTE) also on ferry.

@Vfrpilotpb
That's a 30 Mill€ project, but you know, you can buy nearly allmost on that world and with a small serial production, the price will going down :D :D :D

Due to the computercontrolled handling and flightcharacteristics it should be possible (with the right software) to "inflightsimulate" uncle franks crafts in experimental mode and to go through the barriers without danger. Just flip the "Red" switch and it's the normal EC135. Really impressive imagination :) But it would be difficult to copy the T-bar stick. Could be restricted by copyright ...

[Lu Zuckerman]

To: Techpilot

The calculated failure rate for an electromechanical clutch is approximately 1.5 10 6. Since all four clutches must be available to actuate in the event of a failure warranting the disconnect of one servo the ability to reach 1 10-9 for the system becomes even more difficult to achieve. The collective failure rate for the clutches is 166,666 MTBF.

:eek:

[Nick Lappos]

The Fly-by-light system is an excellent research tool, somewhat transparent from the Fly-by-wire aircraft that have been around, at least as far as the pilot is concerned. The light transmission system (fibre optic) has the advantage of weight and HIRF protection (High Intensity Radiation Fields, like a close by radar) ease. It has disadvantages, mostly in the need for optical transducers for the stick motion detectors which are somewhat risky from a production standpoint (but surely a technology waiting for the chance to prove itself). The first Fly-by-light flights in helicopters took place about 20 years ago, in the ADDOCS H-60 that Boeing Flew as a research aircraft to prove out LHX (now Comanche) control schemes.

The older BO-105 they used was a very capable aircraft, and this EC135 should serve very well.

As far as Lu's pronouncements, the score is about 1,257 : 1 against Lu, since the Boeing 777 and Airbus systems were certified by very stringent governments as meeting the one in a billion chance of catastrophic failure. It is not worth debating Lu, I will not bother, but I'll wage the certificate of Airworthiness for the Boeing 777 can probably trump any post Lu types out.

Now I will lay back and just wait for Lu's response. Let's take a bet how many lines of text he uses to "prove" his point. Any takers? I say more than 23 lines. Do I hear 30?

Nick

[Lu Zuckerman]

To: Nick Lappos

Quote:
“As far as Lu's pronouncements, the score is about 1,257: 1 against Lu, since the Boeing 777 and Airbus systems were certified by very stringent governments as meeting the one in a billion chance of catastrophic failure. It is not worth debating Lu, I will not bother, but I'll wage the certificate of Airworthiness for the Boeing 777 can probably trump any post Lu types out”.

It seems that you are using your position of prominence on this forum to belittle any thing that I say. Well in this case you are totally wrong. You make a simple caustic statement about how many words I will use in responding to your comments above. I could use more if I addressed the explosion of a 737 in Manchester, England or the loss of three 737s due to a rudder malfunction. All of these crashes were due to inadequate testing and or analysis yet these aircraft had a systems failure requirement of 1 10 9.

The Boeing 777 as well as all of the Airbus aircraft were designed to have a system catastrophic failure rate of 1 10 9. This is not the catastrophic failure rate for the aircraft. Considering the total number of critical systems on a complex commercial aircraft and using Boolean Algebra it can be shown that most commercial aircraft have a potential for catastrophic loss of the aircraft somewhere around 10 7 or thereabouts. This also holds true for the 767 and the 737 and most other commercial aircraft. On the 767 they had two incidents where they lost all electrics and they had to navigate and land using the RAT. The total loss of electrics was I believe not to occur more frequently than 1 10 9. The FAA requires that the manufacturers prove their ability to meet this requirement by analysis or test. Since it is much cheaper to perform an analysis the manufacturer in some cases takes the easier route. A case in point. Boeing had to prove the low probability of a deployment in flight of a thrust reverser. On paper the frequency of occurrence of an uncommanded deployment was well below the 1 10-9 requirement so Boeing opted out of performing a test because it was too dangerous. So, they performed a computer analysis, which indicated that the uncommanded deployment was survivable. This satisfied the FAA however; Nikki Lauda proved them wrong.

On the A310 the flaps and slats are not grounded to the airframe and under certain conditions a lightning attachment could cause the wing to blow off. On the same aircraft they experienced during systems test that an internal crack in a power control unit could cause an uncommanded movement of the flaps or slats which were mandated to never occur more than one time in 10 9 flight hours. A change was made but the change will only delay the occurrence of uncommanded movement. Airbus Industrie was not notified of this problem although it was required in the design spec. The same was true for the ungrounded secondary control system. The flap system was inadequately tested on the A 310 and an FMECA was never performed on the flap slat computer. On the first revenue flight from Germany to Egypt an A 310 landed and could not retract the flaps. No amount of troubleshooting could discover the cause. The aircraft had to return to Frankfurt with the flaps fully deployed. Upon its’ return they could not isolate the problem because the flap slat computer could not recognize that a problem existed.

To sum it all up I challenge you to identify any commercial aircraft that has or could meet the 1 10 9 requirement based on the accident record for the fleet. Granted the 777 has not suffered a catastrophic failure but remember these words. Fate is the hunter.

You don’t have to look any further than your S 76. How many blades were lost due to a design error and what were the hours on the fleet at the time of the occurrences? The blades had the same requirement of one catastrophic failure in 10 9 flight hours for the fleet.

:D

[Nick Lappos]

I was right, he couldn't keep it below 23 lines. I count well over 50!

:D

[tecpilot]

@ Lu, really impressive mathematics, :eek:

but one of the "fly by light" ship advantages is the reduced total number of control system moving parts (always a sensitive issue on rotorcrafts). And anyone on that kind of business knows that electromechanical parts doesn't have the 10-9 failure rate. :p

The mechanical emergency controls came to the ship on the last design phase to serve as an "ultima ratio" (last exit) part and should not be used under the normal and experimental modes. The "normal" bypass system for the safety pilot is the "fly by light" system.
If they had ordered a chute for the crewmembers as last chance exit, how would you define the fail safe rate of that old textile? :D

Additionally, as Nick explained, fly-by-light offers, at least theoretically, total resistance to electromagnetic control interference. Some losses of fly-by-wire dependent helos in military training and testing exercise have led to concerns over the battlefield robustness of fly-by-wire systems. Practically, incidents of heavy electromagnetic interference encountered around high-tension power transmission lines have resulted in control troubles for some tech-heavy helicopters and fixed-wing aircraft.

Using your Algebra, what's the all around failure rate on the good ol' but most used crafts? And should we are mad to go up and away with the ships? :D :D :D

[Lu Zuckerman]

To: Nick Lappos

Quote: “I was right, he couldn't keep it below 23 lines. I count well over 50”!

Well at least we know that you can count. Your response is typical of those you made in the past where you tried to vindicate yourself in the eyes of the other contributors to this forum by saying you were right all along but in the process you avoided responding to the technical content of the post.

To: tecpilot

Please understand I am not being critical of the design or the application of the fly-by-light control system, as I believe it is the wave of the future for both aircraft and helicopters. What I was critical of was the statement of having a catastrophic failure rate of 1 10 9. It is the means of determining that it is possible to meet the requirement. Reliability and its’ companion System Safety are totally dependent upon the manipulation of numbers in a database. For any given component you may have as many as 50 different entries showing the failure rates. Notice I indicated rates as opposed to rate as they are all different. In order to calculate the reliability of a system the analyst will pick a number that will allow him/her to show that the system meets the spec requirements. If the analyst can’t find the number he or she is looking for they can pick a number from a component that is used in a totally different environment and multiply it by certain K factors dealing with operational environment. This provides the required number but it does not truly represent the same item that is in the system.

Once the system reliability has been established (on paper) the end failure rates are plugged into a mathematical calculation that is representative of a fault tree. The fault tree consists of And gates and Or gates. On an Or gate any failure that occurs will pass onto the next level. With an And gate all of the failures that feed into it must be present for the failure to pass on to the next level. The failure that passes through any gate is calculated by either adding the entering failure rates or multiplying those failure rates. This process continues upward until the catastrophic failure rate for the system is calculated. Using the failure rates compiled by the reliability engineers who in most cases are not truly representative of the real failure rate the safety engineer runs his calculations. The end result is that at the system level the analyst can show that the system has met or exceeded the requirement for a catastrophic event established by the certifying authorities (As indicated in Nick Lappos’ post above). On one program I worked on the calculations for the systems catastrophic failure rate was as high as 1 10 18 (I can’t even count that high. Maybe Nick can).

There is one major problem in this method. Only system catastrophic failure rates are determined. There is no calculation at the aircraft level. If you can visualize the fault tree with its’ various combinations of And or Or gates then take it one step further and create an Or gate that is representative of the aircraft. Any system failure that can down the aircraft feeds into this Or gate so that any one will cause the loss of the aircraft. If you use the same Boolean Algebra used at the system level then it can be shown that the aircraft does not meet the certification requirements of 1 10 9 catastrophic failure rate. This is the point I was trying to make to Nick Lappos. The 1 10 9 rate is for the systems not the aircraft. I have worked to FAA and JAR requirement as well as Def Stan requirements and the methodology of calculating failure rates at the aircraft level are all the same. To put 1 10 9 in perspective Jesus Christ was born 17,542,776 (approximately) hours ago. The ratio of his birth to 1 10 9 is 1:57. Granted, we are not working with a system in isolation. The 1 10 9 represents accumulated flight hours for the fleet. Lets address a typical long haul jet that flies 3500 hours per year and there are 100 in the fleet. It would take 2,857 years to accumulate one billion hours. Can you visualize any mechanical or electrical system lasting that long or longer prior to catastrophic failure? If you placed an anvil in an airless chamber it would not last that long. Neither will the airless chamber.

However if you employed the approved data bases and used the approved calculation methods the certification authorities will approve the design. The only document related to the whole process that is turned over to the certification authorities is the safety hazards analysis. They never see the FMECAs or the reliability analysis unless they come into the offices of the firms Assurance Engineering Department. It all boils down to Garbage in-Garbage out.

Nick to save you the time in calculating the verbiage in my post here are the stats:

Pages 2 (when prepared in Word)
Characters (no spaces) 3923
Characters (with spaces) 4800
Paragraphs 9
Lines 65

:D

[Dave Jackson]

Lu,

You mentioned " Lets address a typical long haul jet that flies 3500 hours per year and there are 100 in the fleet. It would take 2,857 years to accumulate one billion hours. Can you visualize any mechanical or electrical system lasting that long or longer prior to catastrophic failure? "

Everything eventually 'wears out'; be it people, planes, pyramids or planets. It's just a mater of time.

I don't believe that, when discussing statistics and probability, it is correct to equate [1000 items lasting 1000 hours each] with [1 item lasting 1,000,000 hours]. Would you agree?

[Lu Zuckerman]

To: Dave Jackson

What you say is true however the requirements that govern Reliability at least as far as aircraft are concerned deal with the probability of failure per million hours of operation of the total number of items under analysis. This is expressed as failures per 10 6 hours. In the case of a weapon it might be expressed as shots per million hours of operation per that specific weapon. In some cases it is expressed as cycles per million hours of operation.

When it comes to systems safety especially on commercial aircraft the probability of a catastrophic system failure that can down the aircraft or cause death to the occupants is specified as 1 10 9. Although different certification agencies use different terminology the basic mathematical figures expressing failure are basically the same 1 10 9.

In reliability the probability of failure for one hour of flight is expressed as 1 10-6 and for safety the probability of system failure is expressed as 1 10-9 per hour of flight.


:D

[NigD]

Hey Lu

Is the probability of you not hijacking a thread 1 in 10-9, a good bit of calculation:D

Just kidding Lu, I've enjoyed reading the facts and figures for certification etc, especially working in the aviation industry as a non-pilot (to fund a CPL(H) though), and especially liked the ding-dong battles.

Keeps it interesting

:D :D :D :D

NigD

[What-ho Squiffy!]

I understand that an optical system would confer immunity to HIRF/EMR; but as there are electrons running around in the transducers/actuators/processors of the system, wouldn't these areas be the vulnerable link?

[tecpilot]

@ What-ho Squiffy!

The isolated and theoretical technology itself offers total resistance to electromagnetic control interference.

Fiber is immune to electromagnetic interference, including high intensity radiated fields (HIRF), lightning, aircraft electric power and switching transients and high power microwave, thus improving safety, signal fidelity and reliability. Because information is transmitted in the form of light through fiber, not electricity, "by light" solutions minimize wire and shielding, reducing the risk of sparks and fires as well as weight and cost.
Light in a fibre:
The light propagates along the fibre by the process of total internal reflection. The light is contained within the glass core and cladding by careful design of their refractive indices. The loss along the fibre is low.

But shure we need an interface and from that point electricity is in the game. Electricity and HIRF/EMR means shielding , grounding, filtering and test in a radiation chamber.

Fibre optic is information transmission not information control! ;)

[What-ho Squiffy!]

So, are you saying if the majority of the control system is constructed from fibre optics, and the (electrically operated) interfaces are adequately sheilded, susceptibility to HIRF is reduced to a point where it is negligible?

I suppose the less electrical wire used, the smaller the chance of a current being induced by HIRF?

[Nick Lappos]

What-ho Squiffy!

The light signal running down the fibre-optic link is quite immune to all but the largest burst of radiated energy, but then again so is a well shielded wire (Comanche FBWire is tested to EMP levels - nuclear event stuff!).

Your instinct is quite right, the computation and general control of the flight controls of a fly-by-light are all done by conventional electronics, as are the transducer devices at the servos and in the sticks. These electronics must be shielded just as a FBW system. That being said, the greatest vulnerabilities are in the long runs to and fro in the machine, which is easier to protect in an FBL system.

The greatest advantage of FBL is that the busses that carry the signals has much more signal carrying capacity (bandwidth), although honestly, most flight controls tasks are easily carried in conventional wire busses.

[What-ho Squiffy!]

At the moment it seems that the advantages of FBL are not so great over FBW technology. With this massive bandwidth that FBL offers, do you think we are heading towards a more lofty goal such as active flight control surfaces (for lack of a more techo term)? Is that what the proposed high speed VTOL aircraft will use (I forget the name of it)?

[tecpilot]

@ What-ho Squiffy!

Different ways exits to minimize the influence of HIRF/EMR. But a complete protection is at the moment impossible. We are on the jump to a new helicopter generation, recognicable by a massive use of new generation technologies. The older generation shared the older electrics with barometric instruments. Now we have the new equipment from GSM Phone or special transmitting links as the worst, obstacle warning systems, up to some small or embedded computers in your GPS or displaying unit. They all have their spectrum of radiation with different frequencies and different transmitting power. They all need their data or power links to and from sensors, antennas, displays... And they are have HIRF/EMR problems. That means miles of wires (EC 135 German Border Guard, small Twin but >10 NM wires), massive problems with shielding and detecting HIRF/EMR inducted problems or an ordinary short-circuit, a lot of weight and costs. That's a big disadvantage for the whole aviation industry. "Fly by light" seems at the moment to be the best way to reduce the problem (not to solve utterly). Theoretically could ONE fibre with 235µm core diameter replace the whole stuff of linking wires with little losses (Please, no fail-safe discussion)and 80%-90% of the mechanical linking parts of the control system. Without any HIRF/EMR problem! Two of several available methods:
TDM - Time Division Multiplexing - a method of incorporating many signals into one. Many slower speed signals are sampled onto one high speed signal.
DWDM - Dense Wavelength Division Multiplex
Dense Wavelength Division Multiplexing is a method of expanding the bandwidth of fibre. Many high speed signals are multiplexed together using different wavelength (or colours) for transmission over one fibre.
With that bandwith of transmission, gathering, computing and storing possibilities it would be no problem to develop and to handle the new "crafts" new technologies like smart actuators, active and individual blade control, new FADEC and HUMS systems.
;)