RE: [Flightgear-devel] Electrical system work..
And actually, you get quite a variety of ammeter variation depending on if you are running battery only, have an alternater fail, have the alternator working, have the engine running, and or have a lot of devices and lights going. This change in current must be due to the voltage on the supply changing, thus we actually need to know the resistance of each load, and the output voltage of each source. Then the current on the system is then calculated from Ohm's Law, V=IR, or in this case I=V/R. You probably need to know internal resistances of each power source as well to do a proper model, but that might be a step too far in the first instance. Richard ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
Richard Bytheway wrote: This change in current must be due to the voltage on the supply changing, thus we actually need to know the resistance of each load, and the output voltage of each source. Then the current on the system is then calculated from Ohm's Law, V=IR, or in this case I=V/R. Well, since you know the nomincal current draw and the operating voltage, it is easy to calculate the (average) resistance at runtime. Erik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
The starter motor(s) and APU should also be included in the electrical system. In real life the battery can't keep turning that engine over indefinately. In the light aircraft it might not be such an issue but when you get to the commercial jets you have to be very careful about your startup procedures otherwise you can get yourself into a situation where you have to call for some help from an external power source. Also on most multi engine aircraft you can't start all the engines at once because the battery(s) won't handle the current draw. Paul ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
Paul Surgeon wrote: The starter motor(s) and APU should also be included in the electrical system. In real life the battery can't keep turning that engine over indefinately. In the light aircraft it might not be such an issue but when you get to the commercial jets you have to be very careful about your startup procedures otherwise you can get yourself into a situation where you have to call for some help from an external power source. Also on most multi engine aircraft you can't start all the engines at once because the battery(s) won't handle the current draw. Which raises another issue. To get it one more step more realistic I think it is important to know bot nominal and maximum draw and we should define whether a consumer device is either capacitive or inductive. This is often quite easy to guess (a CRT or everything using motors is inductive) and adds the possibility of popping circuit breakers when too many inductive devices are turned on at once. Not to mention we get more accurate current flows (actually battery lifetime) simulated. Erik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
Hi Gene Gene Buckle writes If you're so stuck on random event generators, go use MSFS. It's full of 'em, including the flight model. I am not stuck on randon event generators it is just that in the real world thats the way things seem to happen.Otherwise they would be planded events.And I can just see someone taking a cessna up knowing that 30 mins into the flight the engine is going to catch fire. How do you determine when the instrument is working normally and when it is not.My guess is the the program is going to say so. The idea here is to be able to create an accurate representation of an aircraft electrical system. Have you ever seen or worked on anything bigger that a light twin electrical system. Lets look at the 747(only because I am most familiar with that) 4 engine driven generators 2 APU driven generators 2 external power connections Then these are spilt up into 115v 3 phase AC 115v single phase AC 28v AC 28v DC ciruits.And then hundreds of CB's.You are not trying to tell me you are going to try and simulate that.The wiring diagrams alone if stacked would be 4 feet high. Every commercial simulator I've worked with has had some kind of electrical system simulation running I have had the fortune of actually opperating 707, 767, 747 and DC10 simulators and yes they have fully functioning electrical systems. But they also have a randon event renerator called a HUMAN and he or she sits at a control panel and selects the system failures. does this not happen in other simulators. The only thing I would ask is if you make these plans to be aware that there a lot of A/C that dont use battery start in fact hardly use a battery at all. And if as I understand FG is a full spectrum simulator then we must consider all types of A/C Cheers Innis The Mad Aussi _ Hot chart ringtones and polyphonics. Go to http://ninemsn.com.au/mobilemania/default.asp ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
Curtis L. Olson [EMAIL PROTECTED] said: I know this is probably comparing apples to oranges, but back when I was young and daring, I drove my car about 150 miles with no alternator belt. I survived by making sure every possible electrical item was turned off. If I even hit the turn signal or hit the brakes (brake lights) the engine would sputter and nearly die. Hehe. I did that...at night...once. It was a much shorter distance, in rural Maine, very late at night. I didn't encountered a single other vehicle on the road, which is a good thing in a way, but at the same time it reinforced the likelyhood that my best option was to keep going. Went _very_ slow after the headlights had to be turned off :-). Fortunately, it was a clear night with a bright moon. Pretty cold without the heater fan though. Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
Lee Elliott writes ...but I have a reasonable founding in it (from about eight years old). Each individual instrument will try to draw it's own current. Assigning ratings to the instruments makes a lot of snese to me, as would the supply capacity of the generator system and batteries. LeeE Why ?.To both this and the WB. As Dave says the empty weight is part of the certification.And I would think it would be more important to worry about fuel ,baggage,passengers and the like than the weight of the ASI. Why you would need to know the current draw of each instrument escape's me.Surely this could be better handled on the power supply side.EG. A fully charged battery will operate the the essential instruments for a given time.If you loose a generator then you loose what ever it was feeding.If it was feeding a buss system then you may not loose anything except the power to the coffee maker. What exactly will this information be used to do???. Cheers Innis The Mad Aussi _ Hot chart ringtones and polyphonics. Go to http://ninemsn.com.au/mobilemania/default.asp ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
Curtis L. Olson writes Innis Cunningham writes: Why ?.To both this and the WB. As Dave says the empty weight is part of the certification.And I would think it would be more important to worry about fuel ,baggage,passengers and the like than the weight of the ASI. Why you would need to know the current draw of each instrument escape's me.Surely this could be better handled on the power supply side.EG. A fully charged battery will operate the the essential instruments for a given time.If you loose a generator then you loose what ever it was feeding.If it was feeding a buss system then you may not loose anything except the power to the coffee maker. What exactly will this information be used to do???. To make the panel's ammeter behave realistically. Seeing how the ampere draw and the voltage would under normal conditions hardly move (except maybe at start). The information could be programmed into the electrical supply system.I assume we are dealing with light A/C here as I doubt anyone flying a 737 would see an amp metre in their life time.If we are talking about failures then would they not be better handled by a random event generator.After all I guess you are going to have a random event generator tell you the instrument is drawing excess current and then pop the C/B.Why not just tell the elecrical system to pop the circuit breaker. To be able to have circuit breakers pop automatically (lower priority). Once again random event generator To be able to have things start on fire when they are really overloaded (really low priority.) And again random event generator. Curt. Cheers Innis The Mad Aussi _ Hot chart ringtones and polyphonics. Go to http://ninemsn.com.au/mobilemania/default.asp ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
Innis Cunningham writes: Seeing how the ampere draw and the voltage would under normal conditions hardly move (except maybe at start). The information could be programmed into the electrical supply system.I assume we are dealing with light A/C here as I doubt anyone flying a 737 would see an amp metre in their life time.If we are talking about failures then would they not be better handled by a random event generator.After all I guess you are going to have a random event generator tell you the instrument is drawing excess current and then pop the C/B.Why not just tell the elecrical system to pop the circuit breaker. To be able to have circuit breakers pop automatically (lower priority). Once again random event generator To be able to have things start on fire when they are really overloaded (really low priority.) And again random event generator. Curt. Ok, how about a 4th reason. :-) Because I'm currently working on a project that would benefit from having the current draw modeled as realistically as possible. And actually, you get quite a variety of ammeter variation depending on if you are running battery only, have an alternater fail, have the alternator working, have the engine running, and or have a lot of devices and lights going. I know this is probably comparing apples to oranges, but back when I was young and daring, I drove my car about 150 miles with no alternator belt. I survived by making sure every possible electrical item was turned off. If I even hit the turn signal or hit the brakes (brake lights) the engine would sputter and nearly die. Anyway, for a C172, and for pilot training, it might be handy to do various electrical system failures. They don't put an ammeter on the panel just because they had extra room and it was cheaper than a tracheon radiation indicator. Alternator failures can happen, and the ammeter (if you are paying attention to it) can give you an early warning of a problem that would perhaps give you time to find a close airport and get on the ground before your lights, radios, and entire electrical system fails. I heard a story about a guy who had to enter a busy pattern, late in the day, with no radios, no lights, (no flaps?). There's no reason an aircraft building would *have* to model the electrical system in this detail. We provide a generic configuration for people who don't want to worry about it ... Regards, Curt. -- Curtis Olson HumanFIRST Program FlightGear Project Twin Citiescurt 'at' me.umn.edu curt 'at' flightgear.org Minnesota http://www.flightgear.org/~curt http://www.flightgear.org ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
On Sunday 16 November 2003 01:08, Innis Cunningham wrote: Curtis L. Olson writes Innis Cunningham writes: Why ?.To both this and the WB. As Dave says the empty weight is part of the certification.And I would think it would be more important to worry about fuel ,baggage,passengers and the like than the weight of the ASI. Why you would need to know the current draw of each instrument escape's me.Surely this could be better handled on the power supply side.EG. A fully charged battery will operate the the essential instruments for a given time.If you loose a generator then you loose what ever it was feeding.If it was feeding a buss system then you may not loose anything except the power to the coffee maker. What exactly will this information be used to do???. To make the panel's ammeter behave realistically. Seeing how the ampere draw and the voltage would under normal conditions hardly move (except maybe at start). The information could be programmed into the electrical supply system.I assume we are dealing with light A/C here as I doubt anyone flying a 737 would see an amp metre in their life time.If we are talking about failures then would they not be better handled by a random event generator.After all I guess you are going to have a random event generator tell you the instrument is drawing excess current and then pop the C/B.Why not just tell the elecrical system to pop the circuit breaker. To be able to have circuit breakers pop automatically (lower priority). Once again random event generator To be able to have things start on fire when they are really overloaded (really low priority.) And again random event generator. Curt. Cheers Innis The Mad Aussi I don't think that having simple random event generators would be realistic. The thing about faults is that they're often, if not usually linked and tend to cascade. Sometimes it can end catastrophically and sometimes not. It'll be easier to incorporate these sorts of scenarios and posibilities if the underlying system follows the real world stuff so we can get real cause and effect. LeeE ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
Seeing how the ampere draw and the voltage would under normal conditions hardly move (except maybe at start). The information could be programmed into the electrical supply system.I assume we are dealing with light A/C here as I doubt anyone flying a 737 would see an amp metre in their life time.If we are talking about failures then would they not be better handled by a random event generator.After all I guess you are going to have a random event generator tell you the instrument is drawing excess current and then pop the C/B.Why not just tell the elecrical system to pop the circuit breaker. To be able to have circuit breakers pop automatically (lower priority). Once again random event generator To be able to have things start on fire when they are really overloaded (really low priority.) And again random event generator. If you're so stuck on random event generators, go use MSFS. It's full of 'em, including the flight model. The idea here is to be able to create an accurate representation of an aircraft electrical system. To be able to do this accurately, building blocks like circuit breakers are required. The model that Curt and I have been hashing back and forth is actually quite straightforward and easy to use. Terminal Reality used a similar method for their electrical systems in Fly! II, but they went so far as to identify individual wires. We're not getting that detailed. (Yet! *laughs*) Every commercial simulator I've worked with has had some kind of electrical system simulation running. Only video games use random event generators in lieu of proper systems. FlightGear is a _simulator_ first and foremost. g. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
.Gene Buckle wrote: Avionics power ratings are always available as nominal and max normal draw. Electrical systems are designed with a bit of extra capacity to deal with power on rush current, etc. The only time an aircraft author would have to give the the current draw any thought at all is if they're also building special avionics and even then, they only really need to specify the nominal draw. The only time the breakers will pop is either on command from an instructor station or via a random systems failure routine. But then there is no need to define amperage in the instruments, is there? Erik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
.Gene Buckle wrote: Avionics power ratings are always available as nominal and max normal draw. Electrical systems are designed with a bit of extra capacity to deal with power on rush current, etc. The only time an aircraft author would have to give the the current draw any thought at all is if they're also building special avionics and even then, they only really need to specify the nominal draw. The only time the breakers will pop is either on command from an instructor station or via a random systems failure routine. But then there is no need to define amperage in the instruments, is there? Yes there is. That's where the load definition belongs. The load figure should follow the equipment, not the bus it's connected to. g. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
Gene Buckle wrote: .Gene Buckle wrote: Avionics power ratings are always available as nominal and max normal draw. Electrical systems are designed with a bit of extra capacity to deal with power on rush current, etc. The only time an aircraft author would have to give the the current draw any thought at all is if they're also building special avionics and even then, they only really need to specify the nominal draw. The only time the breakers will pop is either on command from an instructor station or via a random systems failure routine. But then there is no need to define amperage in the instruments, is there? Yes there is. That's where the load definition belongs. The load figure should follow the equipment, not the bus it's connected to. Ah, I didn't realize those where two separate issues. So we need the nominal power consumption for the battery lifetime and such. That makes sense. This would be an excellent improvement. Erik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Electrical system work..
Also, on some small twin's you can't run everything on only one bus. So if you have a problem with one of the buses or the alternator you will have to shut down some extra stuff or risk draining your battery. Ryan -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Erik Hofman Sent: Friday, November 14, 2003 9:42 AM To: FlightGear developers discussions Subject: Re: [Flightgear-devel] Electrical system work.. Gene Buckle wrote: .Gene Buckle wrote: Avionics power ratings are always available as nominal and max normal draw. Electrical systems are designed with a bit of extra capacity to deal with power on rush current, etc. The only time an aircraft author would have to give the the current draw any thought at all is if they're also building special avionics and even then, they only really need to specify the nominal draw. The only time the breakers will pop is either on command from an instructor station or via a random systems failure routine. But then there is no need to define amperage in the instruments, is there? Yes there is. That's where the load definition belongs. The load figure should follow the equipment, not the bus it's connected to. Ah, I didn't realize those where two separate issues. So we need the nominal power consumption for the battery lifetime and such. That makes sense. This would be an excellent improvement. Erik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
On Friday 14 November 2003 15:42, Erik Hofman wrote: Gene Buckle wrote: .Gene Buckle wrote: Avionics power ratings are always available as nominal and max normal draw. Electrical systems are designed with a bit of extra capacity to deal with power on rush current, etc. The only time an aircraft author would have to give the the current draw any thought at all is if they're also building special avionics and even then, they only really need to specify the nominal draw. The only time the breakers will pop is either on command from an instructor station or via a random systems failure routine. But then there is no need to define amperage in the instruments, is there? Yes there is. That's where the load definition belongs. The load figure should follow the equipment, not the bus it's connected to. Ah, I didn't realize those where two separate issues. So we need the nominal power consumption for the battery lifetime and such. That makes sense. This would be an excellent improvement. Erik I'm not an eletrics scientist... ...but I have a reasonable founding in it (from about eight years old). Each individual instrument will try to draw it's own current. Assigning ratings to the instruments makes a lot of snese to me, as would the supply capacity of the generator system and batteries. LeeE ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
Gene Buckle wrote: In part of my learning the ins and outs of how FG really works, I found another space I can contribute - the electrical system. The current system has no way of handling circuit breakers or measuring a load across a whole bus. The system now expresses a bus like this: bus name.../name prop/systems/electrical/outputs/device/prop prop/systems/electrical/outputs/device2/prop . . . /bus What I propose is something like this: bus name.../name circuit name.../name capacitycapacity_in_amps/capacity prop/systems/electrical/outputs/device/prop prop/systems/electrical/outputs/device2/prop . . . /circuit /bus At this point, the bus can be organized into multiple breaker protected circuits on a single bus. The only part of missing data is the Ampere draw of each device. This could be done within the electrical system definition like this: prop/systems/electrical/outputs/device load=n.n/prop This would be the easy way to supply the data. However, I think it might be better if the power draw figure was part of the instrument definition itself. This would require 2 new tags added to the xml files that are used to define each instrument - I'm referring to the configurationd data found in data/Aircraft/Instruments. This sounds like a good idea, but I expect that the lack of good information spoiled the idea. One might be able to get the power consumption by a device, but often the peak power consumption is much higher. And it's the peak power consumption that causes circuit breakers to pop out. I could imagine that certain actions can cause circuit breakers to pop most of the time on some aircraft, but defining the power consumption based on specific actions might be a little to much to ask for aircraft developers. The first tag would be device-class. This would be something like nav-radio or avionics-fan. It would be used by the load calculator to locate the load value associated with a particular device. The second tag would be load or power-draw or something similar. It would be a double value containing the total draw for the device. When the load calculator comes by, this is the number that gets added to the total (obviously). The idea is to allow custom devices to hold their own power draw values independant of the wiring. For instance, you could change out the stock nav radio for some fancy unit that combines more than one function but has a higher power draw. The device would still be of the class nav-radio but would contain an updated power draw figure. The change would only occur within the instrument panel file and would make sure that no matter the unit installed, the power draw value would follow the device and not the wiring harness. The circuit load would be calculated each time the electrical system's update method is called. If the total load exceeds the circuit capacity for longer than 2 seconds, the breaker would pop and power for that circuit would be cut off. If this is something that you think should be implemented, let me know and I'll start working on the code for it. Erik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Electrical system work..
This would be the easy way to supply the data. However, I think it might be better if the power draw figure was part of the instrument definition itself. This would require 2 new tags added to the xml files that are used to define each instrument - I'm referring to the configurationd data found in data/Aircraft/Instruments. This sounds like a good idea, but I expect that the lack of good information spoiled the idea. One might be able to get the power consumption by a device, but often the peak power consumption is much higher. And it's the peak power consumption that causes circuit breakers to pop out. I could imagine that certain actions can cause circuit breakers to pop most of the time on some aircraft, but defining the power consumption based on specific actions might be a little to much to ask for aircraft developers. Avionics power ratings are always available as nominal and max normal draw. Electrical systems are designed with a bit of extra capacity to deal with power on rush current, etc. The only time an aircraft author would have to give the the current draw any thought at all is if they're also building special avionics and even then, they only really need to specify the nominal draw. The only time the breakers will pop is either on command from an instructor station or via a random systems failure routine. g. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
