EC135 questions for (recreational) sim
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EC135 questions for (recreational) sim
Hello all, long time reader, first time poster.
I'm doing research on building myself an EC135 simulator. First and foremost, I'm not a pilot, so I apologize if my questions are stupid/out of place. The reason I'm building this thing is as much due to an interest in electronics/control theory/automation, as the more obvious love for helicopters. So, I was wondering if I could ask a few questions and hope for a few answers regarding this particular aircraft? I have a couple of questions of immediate interest, and if it's ok I'll revisit this thread when more arise.
First off, hardware, the cyclic: What are the spring forces in the force trim system, roughly? If, hypothetically, I were to move the force feel neutral fully left, what force would I have to put on the stick to put it fully right?
Secondly, hardware, hyd. failure: When suffering a hydraulic failure in one channel, what control forces could I expect respectively on the cyclic, collective and pedals (system 2)? What would be a good way to "emulate" this, a friction brake system acting on the controls, or some sort of damping system (counterforce prop. to speed of control movement)? What about a dual hydraulic failure? Can the controls be moved?
Final question, software (for me at least), the SAS: I've had the opportunity to skim through small parts of training material for this aircraft, and it states something like "after a corrective input, the actuator goes back to its neutral position to ensure full authority" about the basic SAS (not AP-provided, I sadly know nothing about that). Now, here's where my lack of knowledge potentially becomes really apparent, this is uncharted territory for me. If I've gotten this completely wrong, please tell me. But let's consider the yaw-SAS. For a short-term effect, say a gust of wind, I would imagine the SAS correction to go unnoticed by the pilot. What happens with a long term effect, say an increase in torque? Is the SAS a rate damper (always struggling to ensure 0 rotational speed around its axis) or an acceleration damper (always struggling to ensure a constant speed around its axis, i.e. 0 rotational acceleration). Will the SAS see the increase in torque as a prolonged gust of wind and put up a good fight, or will it merely lessen the impact of it, do a small correction to ensure a smooth start in the rotation around the yaw axis, and leave it to the pilot to stop the rotation? A short anecdote on how SAS changed the helicopter pilot's life ("there I was...") would be very valuable for me!
Please note that English is not my native language, if something is totally incomprehendable, I might be able to rephrase it.
Thanks!
I'm doing research on building myself an EC135 simulator. First and foremost, I'm not a pilot, so I apologize if my questions are stupid/out of place. The reason I'm building this thing is as much due to an interest in electronics/control theory/automation, as the more obvious love for helicopters. So, I was wondering if I could ask a few questions and hope for a few answers regarding this particular aircraft? I have a couple of questions of immediate interest, and if it's ok I'll revisit this thread when more arise.
First off, hardware, the cyclic: What are the spring forces in the force trim system, roughly? If, hypothetically, I were to move the force feel neutral fully left, what force would I have to put on the stick to put it fully right?
Secondly, hardware, hyd. failure: When suffering a hydraulic failure in one channel, what control forces could I expect respectively on the cyclic, collective and pedals (system 2)? What would be a good way to "emulate" this, a friction brake system acting on the controls, or some sort of damping system (counterforce prop. to speed of control movement)? What about a dual hydraulic failure? Can the controls be moved?
Final question, software (for me at least), the SAS: I've had the opportunity to skim through small parts of training material for this aircraft, and it states something like "after a corrective input, the actuator goes back to its neutral position to ensure full authority" about the basic SAS (not AP-provided, I sadly know nothing about that). Now, here's where my lack of knowledge potentially becomes really apparent, this is uncharted territory for me. If I've gotten this completely wrong, please tell me. But let's consider the yaw-SAS. For a short-term effect, say a gust of wind, I would imagine the SAS correction to go unnoticed by the pilot. What happens with a long term effect, say an increase in torque? Is the SAS a rate damper (always struggling to ensure 0 rotational speed around its axis) or an acceleration damper (always struggling to ensure a constant speed around its axis, i.e. 0 rotational acceleration). Will the SAS see the increase in torque as a prolonged gust of wind and put up a good fight, or will it merely lessen the impact of it, do a small correction to ensure a smooth start in the rotation around the yaw axis, and leave it to the pilot to stop the rotation? A short anecdote on how SAS changed the helicopter pilot's life ("there I was...") would be very valuable for me!
Please note that English is not my native language, if something is totally incomprehendable, I might be able to rephrase it.
Thanks!
Mate, you've really taken on a MAJOR project for yourself...good luck.
Can I make one TEENSY suggestion. I work in a full motion simulator at the moment, so what I'm about to say is genuine (no sarcasm, seriously).
People who make simulators are generally not pilots and thats what leads to simulators not behaving like real aircraft. If you were a pilot and a software engineer, you'd probably have a better chance of getting it right, but those two fields just don't seem to go together here in the real world (thats my observation anyway).
What I'd suggest is that (a) you get yourself at least SOME time in the aircraft type you want to emulate...have a FEEL of the trim, talk to the people who fly it and have them show you how all the bits and pieces work...the investment will probably be fun and will save you pulling your hair out in clumps trying to figure out what we're saying in PPRUNE. (b) dig into the systems books...as many smart people as there are in this forum, you're never, NEVER going to get the right formula for this without doing both a and b above...again, my opinion and not meant to deter you in any way from your project.
On the SAS question, some flight control systems have both inner loop and outer loop systems. Inner loop inputs arent felt in the controls (ie a gust of wind will be corrected for but you wont feel it in your cyclic or pedals)...outer loop is stuff you'll feel feedback through the controls (maybe an altitude hold...if altitude is low, the collective will actually move up to correct)...now this is a GROSS generalisation and I'm sure it has no bearing on your specific aircraft type (which I know nothing about).
Happy to discuss further...and good luck.
HP
Can I make one TEENSY suggestion. I work in a full motion simulator at the moment, so what I'm about to say is genuine (no sarcasm, seriously).
People who make simulators are generally not pilots and thats what leads to simulators not behaving like real aircraft. If you were a pilot and a software engineer, you'd probably have a better chance of getting it right, but those two fields just don't seem to go together here in the real world (thats my observation anyway).
What I'd suggest is that (a) you get yourself at least SOME time in the aircraft type you want to emulate...have a FEEL of the trim, talk to the people who fly it and have them show you how all the bits and pieces work...the investment will probably be fun and will save you pulling your hair out in clumps trying to figure out what we're saying in PPRUNE. (b) dig into the systems books...as many smart people as there are in this forum, you're never, NEVER going to get the right formula for this without doing both a and b above...again, my opinion and not meant to deter you in any way from your project.
On the SAS question, some flight control systems have both inner loop and outer loop systems. Inner loop inputs arent felt in the controls (ie a gust of wind will be corrected for but you wont feel it in your cyclic or pedals)...outer loop is stuff you'll feel feedback through the controls (maybe an altitude hold...if altitude is low, the collective will actually move up to correct)...now this is a GROSS generalisation and I'm sure it has no bearing on your specific aircraft type (which I know nothing about).
Happy to discuss further...and good luck.
HP
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EC 135 Sim
Bond Air Services Ltd, Staverton Airport, UK have a full 3 axis motion simulator for the EC 135. 
It may be worth a call, or buy yourself a trip in it and see how its done first hand. Good luck with your project. BB
It may be worth a call, or buy yourself a trip in it and see how its done first hand. Good luck with your project. BB
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Thank you both for your comments and suggestions! However, I realize that I've been a bit unclear about what I want to do. The actual flight simulation is going to be provided by X-plane (Laminar Research) and/or Flight Simulator 2004/FSX (Microsoft), so that part is not something I plan on writing myself (atleast not until everything else is working). What I'm going to put together is the cockpit and a visual system. The actual feel of the helicopter, flight dynamics and such, I'll pretty much have to settle for what they can provide, but the hardware feel I can contribute to. I'm slightly involved in a project in this category (recreational sims of complicated aircraft), so I know so much as to say that much can be done to get a fair, not totally unrealistic simulation of the real deal in many cases. I wish to make the EC135 one such case.
So, to make things even more clear (I hope), I will add that I have a pretty good sense of how the mechanical and hydraulic systems of the flight controls are designed in this particular aircraft, I know how the trim actuators are put together and some things like that. What I know nothing about is how these systems feel. I'm looking for statements from the community of pilots here to somehow quantify this, in order for me to build a good representation.
On the SAS, I basically know where the SAS is located in the control loop, I have figures for actuator authority and such, what I would like get a feeling for is the control laws and what sensory inputs the SAS has, also to get a somewhat good representation of the real thing. In this type of simulation, SAS and AP systems are easily put "between stick and simulator" so to say, but in order to write this software, I need some input on how the helicopter feels in this respect.
I've been planning on getting some simulator time, but I plan on waiting a bit longer with that. For one, I suspect it will be hideously expensive, and this is basically a hobby project. Furthermore, I think it would be more productive if I already have a working implementation of my own, to compare to the "reference" simulator the day I've managed to collect enough money and courage to try the real (simulated) thing.
So, further comments are greatly appreciated!
So, to make things even more clear (I hope), I will add that I have a pretty good sense of how the mechanical and hydraulic systems of the flight controls are designed in this particular aircraft, I know how the trim actuators are put together and some things like that. What I know nothing about is how these systems feel. I'm looking for statements from the community of pilots here to somehow quantify this, in order for me to build a good representation.
On the SAS, I basically know where the SAS is located in the control loop, I have figures for actuator authority and such, what I would like get a feeling for is the control laws and what sensory inputs the SAS has, also to get a somewhat good representation of the real thing. In this type of simulation, SAS and AP systems are easily put "between stick and simulator" so to say, but in order to write this software, I need some input on how the helicopter feels in this respect.
I've been planning on getting some simulator time, but I plan on waiting a bit longer with that. For one, I suspect it will be hideously expensive, and this is basically a hobby project. Furthermore, I think it would be more productive if I already have a working implementation of my own, to compare to the "reference" simulator the day I've managed to collect enough money and courage to try the real (simulated) thing.
So, further comments are greatly appreciated!
