Power Expander or not -that's the question
12-04-2008, 04:11 PM
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RE: Power Expander or not -that's the question
I never said planes would fall out of the sky if you don't use a Power Expander.
If you have limited current flow, chances are everything will still work, just not as good as it should.
People have lost planes to limited current flow though. Did you not hear about all the Spektrum rx lockouts which were caused by voltage drops which were caused by limited current flow? This was a big indicator to me that the set ups we had been using were just not up to the task.
We didn't use to have the option of using better set ups, because this new technology wasn't available to us a few years back. We have the option now though.
Jim
If you have limited current flow, chances are everything will still work, just not as good as it should.
People have lost planes to limited current flow though. Did you not hear about all the Spektrum rx lockouts which were caused by voltage drops which were caused by limited current flow? This was a big indicator to me that the set ups we had been using were just not up to the task.
We didn't use to have the option of using better set ups, because this new technology wasn't available to us a few years back. We have the option now though.
Jim
12-04-2008, 05:25 PM
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RE: Power Expander or not -that's the question
ORIGINAL: Hammbone
I never said planes would fall out of the sky if you don't use a Power Expander.
If you have limited current flow, chances are everything will still work, just not as good as it should.
People have lost planes to limited current flow though. Did you not hear about all the Spektrum rx lockouts which were caused by voltage drops which were caused by limited current flow? This was a big indicator to me that the set ups we had been using were just not up to the task.
We didn't use to have the option of using better set ups, because this new technology wasn't available to us a few years back. We have the option now though.
Jim
I never said planes would fall out of the sky if you don't use a Power Expander.
If you have limited current flow, chances are everything will still work, just not as good as it should.
People have lost planes to limited current flow though. Did you not hear about all the Spektrum rx lockouts which were caused by voltage drops which were caused by limited current flow? This was a big indicator to me that the set ups we had been using were just not up to the task.
We didn't use to have the option of using better set ups, because this new technology wasn't available to us a few years back. We have the option now though.
Jim
That was an example of not using the proper battery set up with newer higher amp servos.
12-04-2008, 05:28 PM
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RE: Power Expander or not -that's the question
ORIGINAL: flatspinjim
I'll have my new extra all ready to maiden this weekend but this snow might postpone that! [:@]
I'll have my new extra all ready to maiden this weekend but this snow might postpone that! [:@]
Jim
12-04-2008, 05:47 PM
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RE: Power Expander or not -that's the question
ORIGINAL: exeter_acres
That was an example of not using the proper battery set up with newer higher amp servos.
ORIGINAL: Hammbone
I never said planes would fall out of the sky if you don't use a Power Expander.
If you have limited current flow, chances are everything will still work, just not as good as it should.
People have lost planes to limited current flow though. Did you not hear about all the Spektrum rx lockouts which were caused by voltage drops which were caused by limited current flow? This was a big indicator to me that the set ups we had been using were just not up to the task.
We didn't use to have the option of using better set ups, because this new technology wasn't available to us a few years back. We have the option now though.
Jim
I never said planes would fall out of the sky if you don't use a Power Expander.
If you have limited current flow, chances are everything will still work, just not as good as it should.
People have lost planes to limited current flow though. Did you not hear about all the Spektrum rx lockouts which were caused by voltage drops which were caused by limited current flow? This was a big indicator to me that the set ups we had been using were just not up to the task.
We didn't use to have the option of using better set ups, because this new technology wasn't available to us a few years back. We have the option now though.
Jim
That was an example of not using the proper battery set up with newer higher amp servos.
Some were batteries with low current output ratings, some were regulators with low amp ratings, some had wiring that was not capable of passing enough current, some had inline switches with insufficient ratings, some used standard plugs in areas where they shouldn't have, etc., etc.
The point is, limited current flow is not a good thing, and we should try to avoid it now that we can.
You are correct in mentioning the new higher amp servos we have now. They use more curent than ever, which makes it even more important to upgrade our power distribution systems.
A Power Expander is not the only way to improve your current flow, but it's probably one of the best ways to do so.
You have to look at the complete system though. One weak link and you have limited current flow.
As mentioned earlier, some Li Ion batteries are rated at only 4 amps output. Even if you use these batteries with a Power Expander, you are limited to 4 amps per battery. If you use 2 batteries you have limited yourself to 8 amps, even if you use a Power Expander. I used these Li Ion batteries for years with regulators and inline switches. I didn't realize it at the time, but I probably had limited current flow. I didn't know any better at the time, and we really didn't have many other options available to us back then.
We've come a long way in the past few years though, and we have many good options available to us now to improve our current flow.
Every single component in your set up is important. All it takes is one item that's not up to the task, and you have limited current flow. Keep it simple, but make sure each component is capable of supplying the current flow you need.
Power Expanders are our friends, not our enemies.
The JR Powersafe rx's are a great new device available to us now as well. Jr has taken some of the best features of a Power Expander (high current inputs and failsafe switch) and put them into their Powersafe rx's for us.
Jim
12-05-2008, 12:18 AM
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RE: Power Expander or not -that's the question
So I guess it boils down to those that know what they are doing don't need an expander for safe flight while those that don't have a clue need one. The so called "drop outs" are an age old problem. If you didn't get enough juice to the receiver nothing worked. Too small or a run down battery and you hit the ground. Same thing happens in a battery powered flash light. It quits working when the battery goes daed. So what's really changed?
The new high amp servos only draw the amperage they need to overcome the load imposed. Most everything that's set up as it should be doesn't really have that high of a load. Those set up with binds or with under sized servos will draw a lot more. So once again it comes back to those who know what they are doing succeed while those that don't have to spring for extra equipment with the hope of over coming other weak points through additional accessories.
I'm not at all against expanders, but I am of the opinion that they have been glorified as the cure for a problem that was never there.
The new high amp servos only draw the amperage they need to overcome the load imposed. Most everything that's set up as it should be doesn't really have that high of a load. Those set up with binds or with under sized servos will draw a lot more. So once again it comes back to those who know what they are doing succeed while those that don't have to spring for extra equipment with the hope of over coming other weak points through additional accessories.
I'm not at all against expanders, but I am of the opinion that they have been glorified as the cure for a problem that was never there.
12-05-2008, 01:44 PM
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RE: Power Expander or not -that's the question
ORIGINAL: mrbigg
"I'm not at all against expanders, but I am of the opinion that they have been glorified as the cure for a problem that was never there." [sm=lol.gif][sm=lol.gif][sm=lol.gif]
"I'm not at all against expanders, but I am of the opinion that they have been glorified as the cure for a problem that was never there." [sm=lol.gif][sm=lol.gif][sm=lol.gif]
That could be the post of the year....
I agree
12-06-2008, 05:23 AM
#87
RE: Power Expander or not -that's the question
Power systems are nice, and they do provide piece of mind, and I can understand how a "need" for them was "created".
However, I have personally seen a 42% 260 fly with a single futaba 72mhz receiver and 9 high-powered servos, and it was being fed by a single 3,000ish mah 5-cell nimh through s standard HD switch with a SINGLE lead plugged into the receiver.
Not only did I see this install, I saw it fly, and it wasn't just flying, it was flying in the Invitational class at the 2007 Tucson Aerobatic Shootout, and it performed well enough for a 7th place finish. That right there goes to show that fancy power systems really aren't necessary.
I have done it both ways - heck, all sorts of different ways!
My last 100cc plane had a Power Expander Pro to distribute power to 7 high powered servos and an AR9000 receiver. I liked the smart switch and batt share technology built into it, and I liked knowing that my receiver had it's own source of power (two A123 2300's were up to the task).
My current 42% IMAC bird has the AR9100. It is all the features of a power expander pro, except for the multiple output ports per channel, which I really don't need anyway. This is the simplest and most effective setup I have ever done!
My current 100cc bird has an AR9000 powered by two A123 1100's through a wolverine switch, and then the receiver has a DC-up blugged into it for back-up power. I like this setup, but if I didn't already have the AR9000 sitting around, I would have just gone with another AR9100...
However, I have personally seen a 42% 260 fly with a single futaba 72mhz receiver and 9 high-powered servos, and it was being fed by a single 3,000ish mah 5-cell nimh through s standard HD switch with a SINGLE lead plugged into the receiver.
Not only did I see this install, I saw it fly, and it wasn't just flying, it was flying in the Invitational class at the 2007 Tucson Aerobatic Shootout, and it performed well enough for a 7th place finish. That right there goes to show that fancy power systems really aren't necessary.
I have done it both ways - heck, all sorts of different ways!
My last 100cc plane had a Power Expander Pro to distribute power to 7 high powered servos and an AR9000 receiver. I liked the smart switch and batt share technology built into it, and I liked knowing that my receiver had it's own source of power (two A123 2300's were up to the task).
My current 42% IMAC bird has the AR9100. It is all the features of a power expander pro, except for the multiple output ports per channel, which I really don't need anyway. This is the simplest and most effective setup I have ever done!
My current 100cc bird has an AR9000 powered by two A123 1100's through a wolverine switch, and then the receiver has a DC-up blugged into it for back-up power. I like this setup, but if I didn't already have the AR9000 sitting around, I would have just gone with another AR9100...
12-06-2008, 09:20 AM
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RE: Power Expander or not -that's the question
ORIGINAL: bodywerks
However, I have personally seen a 42% 260 fly with a single futaba 72mhz receiver and 9 high-powered servos, and it was being fed by a single 3,000ish mah 5-cell nimh through s standard HD switch with a SINGLE lead plugged into the receiver.
Not only did I see this install, I saw it fly, and it wasn't just flying, it was flying in the Invitational class at the 2007 Tucson Aerobatic Shootout, and it performed well enough for a 7th place finish. That right there goes to show that fancy power systems really aren't necessary.
However, I have personally seen a 42% 260 fly with a single futaba 72mhz receiver and 9 high-powered servos, and it was being fed by a single 3,000ish mah 5-cell nimh through s standard HD switch with a SINGLE lead plugged into the receiver.
Not only did I see this install, I saw it fly, and it wasn't just flying, it was flying in the Invitational class at the 2007 Tucson Aerobatic Shootout, and it performed well enough for a 7th place finish. That right there goes to show that fancy power systems really aren't necessary.
It sounds like you are saying a set up like this is O.K. to use. I hope that's not what you are saying. To come on here and basically say that a set up like this is fine is both irresponsible, and disrespectful to other people in this hobby. Do you want other pilots planes to fail or operate poorly because you said a set up like this is fine? Are you flying a set up like this? I doubt it. No one in their right mind with an ounce of knowledge would ever recommend a set up like this.
I really hate to see bad info like this put forth on the forums. Please don't anybody try a set up like this, unless you hate your plane and want to lose it.
Jim
12-06-2008, 12:10 PM
#89
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RE: Power Expander or not -that's the question
So noiw the next question becomes one of asking who is posting in this thread that might be sponsored or employed by a company making power expanders? DEvery new product that comes out is usually "pushed" by one or a few people that fly lots of public exposure, high visibility events and obtain those products for free.
A lot of products have made the market that were nice to have and use but not creitically necessary. Power Expanders just happen to be one of them. As for irrresponsible, anyone that makes it to a major event in the invitational class is rarely irresponsible, and generally rather savvy about what they fly. They might fall into a "reckless" category because they will risk the plane everytime in order to win, bu that's not the same as irresponsible. A single receiver buss will handle all the current any of the planes currently on the market will ever need to fly safe and effectively.
A lot of products have made the market that were nice to have and use but not creitically necessary. Power Expanders just happen to be one of them. As for irrresponsible, anyone that makes it to a major event in the invitational class is rarely irresponsible, and generally rather savvy about what they fly. They might fall into a "reckless" category because they will risk the plane everytime in order to win, bu that's not the same as irresponsible. A single receiver buss will handle all the current any of the planes currently on the market will ever need to fly safe and effectively.
12-06-2008, 12:30 PM
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RE: Power Expander or not -that's the question
To answer your question, I am not sponsored by anyone.
Yes, a single rx bus will handle the current, but you are not going to push enough current for 9 high power servos through one standard connector that is going into that rx, not even close.
Tired Old Man, you still don't get it.
Jim
Yes, a single rx bus will handle the current, but you are not going to push enough current for 9 high power servos through one standard connector that is going into that rx, not even close.
Tired Old Man, you still don't get it.
Jim
12-06-2008, 12:59 PM
#91
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RE: Power Expander or not -that's the question
First, I don't supply a receiver with only one battery plug, so I most certainly DO "get it". When I can input 4 battery leads into a receiver (that's up to 16 amps at standard draw rates btw) the receiver will have no problem at all pumping all of it back out to the servos. Now will the receiver EVER have an issue with a "brownout" as long as I keep the batteries charged. Will I EVER NEED 16 (or more) amps? I seriously doubt it. I haven't needed it yet on a multiple servo per surface plane and unless I intened to use 4 or more servos per surface I doubt I ever will. Now if I wanted to go waaaay over the top I might simply run power direct to a matchbox or two in a 4 servo application, providing even more direct amperage to those groups of servos and augmenting the receiver power supply. Now using all the burst capacity that available in a pair of A 123, 2,300 mAh batteries you would melt all the connectors in a power expander just as easily as a receiver. At 50 to 80 amps burst per battery it would not matter what you used because the ser vos would go up in flames if that power ever got to them.
I don't think you get it. People that understand how to set up servos, calc the line losses incurred by long extensions, and use servos sized to the application and use, just don't need all the whistles and bells that others seem to. I don't go to a field to wow anyone with all the neat widgets I have in the plane, I go to fly. How much I spent to get the fancy doodads doesn't impress anyone. What does is how effective and safe the system in use works, and if done economically, makes it even sweeter. You fail to consider that a lot of the problems people have encountered have likely been because all the factory research for the 2.4 systems was not complete before they marketed their products and the customers were used as lab subjects. That's why all the later accessory add ons hit the market. A simple attempt to offset the deficiencies originally marketed with the 2.4 systems. Now factor in the number of people that don't understand how to set up a single servo installation, let alone a multiple servo installation, and you magnify the failure rate even further. Now add in the almost total lack of system information provided in the 2.4 radio instructions and perhaps you might finally start to "get it".
BTW, if your servo leads are longer than 5 feet you better be pumping about 8v to the servos if you want to have 6v at the servo end. That presumes you have at least one connector or solder joint somewhere in the servo wire. Can your expander provide that on a per channel basis? Most adjustable regulators don't.
I don't think you get it. People that understand how to set up servos, calc the line losses incurred by long extensions, and use servos sized to the application and use, just don't need all the whistles and bells that others seem to. I don't go to a field to wow anyone with all the neat widgets I have in the plane, I go to fly. How much I spent to get the fancy doodads doesn't impress anyone. What does is how effective and safe the system in use works, and if done economically, makes it even sweeter. You fail to consider that a lot of the problems people have encountered have likely been because all the factory research for the 2.4 systems was not complete before they marketed their products and the customers were used as lab subjects. That's why all the later accessory add ons hit the market. A simple attempt to offset the deficiencies originally marketed with the 2.4 systems. Now factor in the number of people that don't understand how to set up a single servo installation, let alone a multiple servo installation, and you magnify the failure rate even further. Now add in the almost total lack of system information provided in the 2.4 radio instructions and perhaps you might finally start to "get it".
BTW, if your servo leads are longer than 5 feet you better be pumping about 8v to the servos if you want to have 6v at the servo end. That presumes you have at least one connector or solder joint somewhere in the servo wire. Can your expander provide that on a per channel basis? Most adjustable regulators don't.
12-06-2008, 01:48 PM
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RE: Power Expander or not -that's the question
You were defending the set up mentioned above that used one standard connector going into a rx to power 9 high power servos. If you agree that one standard connector is not enough, why were you defending that set up?
Yes, losses are incurred by long extensions, but I bet you don't know that the Power Expanders make up for this too, if I understand it correctly. It says right on the Smart Fly website that the Power Expanders have: Long servo lead line matching. I'm not sure about this, but I think that means that the Power Expander boosts the signal and the current flow on long extensions to equal things out (someone correct me if I'm wrong). Even if I am wrong on this, you're still better off with a Power Expander because it provides for several output ports per channel. It's much better to have each servo have it's own power source than to have servos ganged together with "Y"s and plugged into one channel through on standard plug on a rx without a Power Expander. This is especially true with long extensions.
There were problems with the early Spektrum rx's taking too long to reboot under low voltage cut out situations. The rx's did not cause limited current flow, they showed the limited current flow problems that were already present due to poor power distribution set ups. These rx's brought the problem to light. Before this, most of us had no idea we had limited current flow problems. It was a real eye opener to me! Guys had been flying around for a long time with a 72Mhz rx, then they put in a 2.4Ghz rx and had a rx brown out due to limited current flow. A lot of them lost their planes because of this. The only thing they changed was the rx. The 72Mhz rx just kept working, even though they had low voltage caused by limited curent flow, but they early Spektrum rx's would cut off when voltage dropped below a certain point. The rx was not really the cause, the limited current flow was the cause. If they would have had better power distribution set ups, this would not have happened.
You don't seem to know much about Power Expanders. First you said they drop the voltage, now you're saying they don't compensate for long servo leads. Do yourself a favor and read up on them. Try to keep an open mind. You may just figure out how good they are.
What in the world could you possibly have against them anyway? The added cost? You just said you were willing to buy a couple of matchboxes if needed. Two matchboxes cost about the same as the entry level Power Expander does, you'd get a lot more bang for your buck with a Power Expander though. So please tell me, what do you have against Power Expanders? Name one bad feature of a Power Expander, or tell me one thing that it can't do, that your set ups can do.
Jim
Yes, losses are incurred by long extensions, but I bet you don't know that the Power Expanders make up for this too, if I understand it correctly. It says right on the Smart Fly website that the Power Expanders have: Long servo lead line matching. I'm not sure about this, but I think that means that the Power Expander boosts the signal and the current flow on long extensions to equal things out (someone correct me if I'm wrong). Even if I am wrong on this, you're still better off with a Power Expander because it provides for several output ports per channel. It's much better to have each servo have it's own power source than to have servos ganged together with "Y"s and plugged into one channel through on standard plug on a rx without a Power Expander. This is especially true with long extensions.
There were problems with the early Spektrum rx's taking too long to reboot under low voltage cut out situations. The rx's did not cause limited current flow, they showed the limited current flow problems that were already present due to poor power distribution set ups. These rx's brought the problem to light. Before this, most of us had no idea we had limited current flow problems. It was a real eye opener to me! Guys had been flying around for a long time with a 72Mhz rx, then they put in a 2.4Ghz rx and had a rx brown out due to limited current flow. A lot of them lost their planes because of this. The only thing they changed was the rx. The 72Mhz rx just kept working, even though they had low voltage caused by limited curent flow, but they early Spektrum rx's would cut off when voltage dropped below a certain point. The rx was not really the cause, the limited current flow was the cause. If they would have had better power distribution set ups, this would not have happened.
You don't seem to know much about Power Expanders. First you said they drop the voltage, now you're saying they don't compensate for long servo leads. Do yourself a favor and read up on them. Try to keep an open mind. You may just figure out how good they are.
What in the world could you possibly have against them anyway? The added cost? You just said you were willing to buy a couple of matchboxes if needed. Two matchboxes cost about the same as the entry level Power Expander does, you'd get a lot more bang for your buck with a Power Expander though. So please tell me, what do you have against Power Expanders? Name one bad feature of a Power Expander, or tell me one thing that it can't do, that your set ups can do.
Jim
12-06-2008, 03:42 PM
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RE: Power Expander or not -that's the question
If you have extra long servo leads, you could put 4 power expanders in and it would not "get" any more voltage to the servo than if you did not have one at all. You only get out what you put in.(actually a little less) There is no way to "boost" voltage and current. If you step up voltage you lose current. If you step down voltage you can can use more of your available current however you now have less pushing it, so that would not make sense. The way I kinda' see it is that power expanders tidy things up, wich is sweet and I will own one just for that reason. The only cure for long servo leads is proper source voltage, and a power cell capable of delivering the current needed.
ORIGINAL: Hammbone
You were defending the set up mentioned above that used one standard connector going into a rx to power 9 high power servos. If you agree that one standard connector is not enough, why were you defending that set up?
Yes, losses are incurred by long extensions, but I bet you don't know that the Power Expanders make up for this too, if I understand it correctly. It says right on the Smart Fly website that the Power Expanders have: Long servo lead line matching. I'm not sure about this, but I think that means that the Power Expander boosts the signal and the current flow on long extensions to equal things out (someone correct me if I'm wrong). Even if I am wrong on this, you're still better off with a Power Expander because it provides for several output ports per channel. It's much better to have each servo have it's own power source than to have servos ganged together with "Y"s and plugged into one channel through on standard plug on a rx without a Power Expander. This is especially true with long extensions.
There were problems with the early Spektrum rx's taking too long to reboot under low voltage cut out situations. The rx's did not cause limited current flow, they showed the limited current flow problems that were already present due to poor power distribution set ups. These rx's brought the problem to light. Before this, most of us had no idea we had limited current flow problems. It was a real eye opener to me! Guys had been flying around for a long time with a 72Mhz rx, then they put in a 2.4Ghz rx and had a rx brown out due to limited current flow. A lot of them lost their planes because of this. The only thing they changed was the rx. The 72Mhz rx just kept working, even though they had low voltage caused by limited curent flow, but they early Spektrum rx's would cut off when voltage dropped below a certain point. The rx was not really the cause, the limited current flow was the cause. If they would have had better power distribution set ups, this would not have happened.
You don't seem to know much about Power Expanders. First you said they drop the voltage, now you're saying they don't compensate for long servo leads. Do yourself a favor and read up on them. Try to keep an open mind. You may just figure out how good they are.
What in the world could you possibly have against them anyway? The added cost? You just said you were willing to buy a couple of matchboxes if needed. Two matchboxes cost about the same as the entry level Power Expander does, you'd get a lot more bang for your buck with a Power Expander though. So please tell me, what do you have against Power Expanders? Name one bad feature of a Power Expander, or tell me one thing that it can't do, that your set ups can do.
Jim
You were defending the set up mentioned above that used one standard connector going into a rx to power 9 high power servos. If you agree that one standard connector is not enough, why were you defending that set up?
Yes, losses are incurred by long extensions, but I bet you don't know that the Power Expanders make up for this too, if I understand it correctly. It says right on the Smart Fly website that the Power Expanders have: Long servo lead line matching. I'm not sure about this, but I think that means that the Power Expander boosts the signal and the current flow on long extensions to equal things out (someone correct me if I'm wrong). Even if I am wrong on this, you're still better off with a Power Expander because it provides for several output ports per channel. It's much better to have each servo have it's own power source than to have servos ganged together with "Y"s and plugged into one channel through on standard plug on a rx without a Power Expander. This is especially true with long extensions.
There were problems with the early Spektrum rx's taking too long to reboot under low voltage cut out situations. The rx's did not cause limited current flow, they showed the limited current flow problems that were already present due to poor power distribution set ups. These rx's brought the problem to light. Before this, most of us had no idea we had limited current flow problems. It was a real eye opener to me! Guys had been flying around for a long time with a 72Mhz rx, then they put in a 2.4Ghz rx and had a rx brown out due to limited current flow. A lot of them lost their planes because of this. The only thing they changed was the rx. The 72Mhz rx just kept working, even though they had low voltage caused by limited curent flow, but they early Spektrum rx's would cut off when voltage dropped below a certain point. The rx was not really the cause, the limited current flow was the cause. If they would have had better power distribution set ups, this would not have happened.
You don't seem to know much about Power Expanders. First you said they drop the voltage, now you're saying they don't compensate for long servo leads. Do yourself a favor and read up on them. Try to keep an open mind. You may just figure out how good they are.
What in the world could you possibly have against them anyway? The added cost? You just said you were willing to buy a couple of matchboxes if needed. Two matchboxes cost about the same as the entry level Power Expander does, you'd get a lot more bang for your buck with a Power Expander though. So please tell me, what do you have against Power Expanders? Name one bad feature of a Power Expander, or tell me one thing that it can't do, that your set ups can do.
Jim
12-06-2008, 06:28 PM
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RE: Power Expander or not -that's the question
ORIGINAL: houdinimkii
If you have extra long servo leads, you could put 4 power expanders in and it would not "get" any more voltage to the servo than if you did not have one at all. You only get out what you put in.(actually a little less) There is no way to "boost" voltage and current. If you step up voltage you lose current. If you step down voltage you can can use more of your available current however you now have less pushing it, so that would not make sense. The way I kinda' see it is that power expanders tidy things up, wich is sweet and I will own one just for that reason. The only cure for long servo leads is proper source voltage, and a power cell capable of delivering the current needed.
If you have extra long servo leads, you could put 4 power expanders in and it would not "get" any more voltage to the servo than if you did not have one at all. You only get out what you put in.(actually a little less) There is no way to "boost" voltage and current. If you step up voltage you lose current. If you step down voltage you can can use more of your available current however you now have less pushing it, so that would not make sense. The way I kinda' see it is that power expanders tidy things up, wich is sweet and I will own one just for that reason. The only cure for long servo leads is proper source voltage, and a power cell capable of delivering the current needed.
ORIGINAL: Hammbone
You were defending the set up mentioned above that used one standard connector going into a rx to power 9 high power servos. If you agree that one standard connector is not enough, why were you defending that set up?
Yes, losses are incurred by long extensions, but I bet you don't know that the Power Expanders make up for this too, if I understand it correctly. It says right on the Smart Fly website that the Power Expanders have: Long servo lead line matching. I'm not sure about this, but I think that means that the Power Expander boosts the signal and the current flow on long extensions to equal things out (someone correct me if I'm wrong). Even if I am wrong on this, you're still better off with a Power Expander because it provides for several output ports per channel. It's much better to have each servo have it's own power source than to have servos ganged together with "Y"s and plugged into one channel through on standard plug on a rx without a Power Expander. This is especially true with long extensions.
There were problems with the early Spektrum rx's taking too long to reboot under low voltage cut out situations. The rx's did not cause limited current flow, they showed the limited current flow problems that were already present due to poor power distribution set ups. These rx's brought the problem to light. Before this, most of us had no idea we had limited current flow problems. It was a real eye opener to me! Guys had been flying around for a long time with a 72Mhz rx, then they put in a 2.4Ghz rx and had a rx brown out due to limited current flow. A lot of them lost their planes because of this. The only thing they changed was the rx. The 72Mhz rx just kept working, even though they had low voltage caused by limited curent flow, but they early Spektrum rx's would cut off when voltage dropped below a certain point. The rx was not really the cause, the limited current flow was the cause. If they would have had better power distribution set ups, this would not have happened.
You don't seem to know much about Power Expanders. First you said they drop the voltage, now you're saying they don't compensate for long servo leads. Do yourself a favor and read up on them. Try to keep an open mind. You may just figure out how good they are.
What in the world could you possibly have against them anyway? The added cost? You just said you were willing to buy a couple of matchboxes if needed. Two matchboxes cost about the same as the entry level Power Expander does, you'd get a lot more bang for your buck with a Power Expander though. So please tell me, what do you have against Power Expanders? Name one bad feature of a Power Expander, or tell me one thing that it can't do, that your set ups can do.
Jim
You were defending the set up mentioned above that used one standard connector going into a rx to power 9 high power servos. If you agree that one standard connector is not enough, why were you defending that set up?
Yes, losses are incurred by long extensions, but I bet you don't know that the Power Expanders make up for this too, if I understand it correctly. It says right on the Smart Fly website that the Power Expanders have: Long servo lead line matching. I'm not sure about this, but I think that means that the Power Expander boosts the signal and the current flow on long extensions to equal things out (someone correct me if I'm wrong). Even if I am wrong on this, you're still better off with a Power Expander because it provides for several output ports per channel. It's much better to have each servo have it's own power source than to have servos ganged together with "Y"s and plugged into one channel through on standard plug on a rx without a Power Expander. This is especially true with long extensions.
There were problems with the early Spektrum rx's taking too long to reboot under low voltage cut out situations. The rx's did not cause limited current flow, they showed the limited current flow problems that were already present due to poor power distribution set ups. These rx's brought the problem to light. Before this, most of us had no idea we had limited current flow problems. It was a real eye opener to me! Guys had been flying around for a long time with a 72Mhz rx, then they put in a 2.4Ghz rx and had a rx brown out due to limited current flow. A lot of them lost their planes because of this. The only thing they changed was the rx. The 72Mhz rx just kept working, even though they had low voltage caused by limited curent flow, but they early Spektrum rx's would cut off when voltage dropped below a certain point. The rx was not really the cause, the limited current flow was the cause. If they would have had better power distribution set ups, this would not have happened.
You don't seem to know much about Power Expanders. First you said they drop the voltage, now you're saying they don't compensate for long servo leads. Do yourself a favor and read up on them. Try to keep an open mind. You may just figure out how good they are.
What in the world could you possibly have against them anyway? The added cost? You just said you were willing to buy a couple of matchboxes if needed. Two matchboxes cost about the same as the entry level Power Expander does, you'd get a lot more bang for your buck with a Power Expander though. So please tell me, what do you have against Power Expanders? Name one bad feature of a Power Expander, or tell me one thing that it can't do, that your set ups can do.
Jim
Jim
12-06-2008, 06:54 PM
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RE: Power Expander or not -that's the question
Clever marketing... maybe, I dont know. If they have somehow come up with some new loop hole around Ohms law I'd love to get in on it!
Good clean high flow connections and busses, that minimize voltage drop, sure. It all comes down to matching source to load i.e. servos, connections, length of wire, load imposed on servo.... ect. If you were to get into the engineering side of we would be here all week. All I'm sayin' is you cannot "boost" voltage without an ampere trade off, unless your "boost" is source voltage.
Good clean high flow connections and busses, that minimize voltage drop, sure. It all comes down to matching source to load i.e. servos, connections, length of wire, load imposed on servo.... ect. If you were to get into the engineering side of we would be here all week. All I'm sayin' is you cannot "boost" voltage without an ampere trade off, unless your "boost" is source voltage.
12-06-2008, 10:33 PM
#96
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RE: Power Expander or not -that's the question
Thank you. That saved me a lot of work and typing.
As I've said before, I have nothing against power expanders, juswt that they are not genrally necessary. There are and have been far too many large scale planes flying around with extreme effectiveness for too long without a power expander, proving their lack of need. They are one more fairly complicated piece of electrical equipment tossed into a system creating another failure source point. The more complicated the equipment, the greater the chance of failure. I know that syndrome much too well to have any doubts about it.
If you feel you just gotta have a power expander, then by all means get one. A pair of Matchboxes at $125.00 may cost close to an entry level expander but they are pretty damn easy to set up and a lot easier to locate inside a fuselage. If you split receivers you wouldn't even need to think about a matchbox in most cases, again eliminating any need for an expander. All you need is volts, amps, and the means to deliver both to the working end of the system. The receiver generally fills that category quite well.
I really don't even feel a need to argue it any any further. Want one? Then get one. Just don't tell people they are an absolute necessity in order to operate a safe flight system in a responsible manner.
As I've said before, I have nothing against power expanders, juswt that they are not genrally necessary. There are and have been far too many large scale planes flying around with extreme effectiveness for too long without a power expander, proving their lack of need. They are one more fairly complicated piece of electrical equipment tossed into a system creating another failure source point. The more complicated the equipment, the greater the chance of failure. I know that syndrome much too well to have any doubts about it.
If you feel you just gotta have a power expander, then by all means get one. A pair of Matchboxes at $125.00 may cost close to an entry level expander but they are pretty damn easy to set up and a lot easier to locate inside a fuselage. If you split receivers you wouldn't even need to think about a matchbox in most cases, again eliminating any need for an expander. All you need is volts, amps, and the means to deliver both to the working end of the system. The receiver generally fills that category quite well.
I really don't even feel a need to argue it any any further. Want one? Then get one. Just don't tell people they are an absolute necessity in order to operate a safe flight system in a responsible manner.
12-06-2008, 11:46 PM
#98
RE: Power Expander or not -that's the question
ORIGINAL: Hammbone
If he would have done this with one of the early Spektrum rx's, I would bet good money that he would have lost the plane due to rx lockout (brown out) caused by limited current flow. There are many, many guys that this happened to with better set ups than this.
It sounds like you are saying a set up like this is O.K. to use. I hope that's not what you are saying. To come on here and basically say that a set up like this is fine is both irresponsible, and disrespectful to other people in this hobby. Do you want other pilots planes to fail or operate poorly because you said a set up like this is fine? Are you flying a set up like this? I doubt it. No one in their right mind with an ounce of knowledge would ever recommend a set up like this.
I really hate to see bad info like this put forth on the forums. Please don't anybody try a set up like this, unless you hate your plane and want to lose it.
Jim
ORIGINAL: bodywerks
However, I have personally seen a 42% 260 fly with a single futaba 72mhz receiver and 9 high-powered servos, and it was being fed by a single 3,000ish mah 5-cell nimh through s standard HD switch with a SINGLE lead plugged into the receiver.
Not only did I see this install, I saw it fly, and it wasn't just flying, it was flying in the Invitational class at the 2007 Tucson Aerobatic Shootout, and it performed well enough for a 7th place finish. That right there goes to show that fancy power systems really aren't necessary.
However, I have personally seen a 42% 260 fly with a single futaba 72mhz receiver and 9 high-powered servos, and it was being fed by a single 3,000ish mah 5-cell nimh through s standard HD switch with a SINGLE lead plugged into the receiver.
Not only did I see this install, I saw it fly, and it wasn't just flying, it was flying in the Invitational class at the 2007 Tucson Aerobatic Shootout, and it performed well enough for a 7th place finish. That right there goes to show that fancy power systems really aren't necessary.
It sounds like you are saying a set up like this is O.K. to use. I hope that's not what you are saying. To come on here and basically say that a set up like this is fine is both irresponsible, and disrespectful to other people in this hobby. Do you want other pilots planes to fail or operate poorly because you said a set up like this is fine? Are you flying a set up like this? I doubt it. No one in their right mind with an ounce of knowledge would ever recommend a set up like this.
I really hate to see bad info like this put forth on the forums. Please don't anybody try a set up like this, unless you hate your plane and want to lose it.
Jim
The fact that the guy that did this was an Invitational-class pilot and a Futaba factory team pilot and a 7th place finisher at the TAS should show that he is not an ignorant idiot. He has also made it to the finals at every TOC he ever competed at and finished as high as 3rd. He has been flying for a while so his setups have come from experience, probably more experience than you or I combined.
Sure, there are other factors I didn't mention in that post, like the plane was only 36 pounds and the geometry on the servos wasn't set up for 3D, but the fact that it was a plane that was flown in a precision aerobatics contest eludes to a high-resolution setup and not a 3D throw setup, and that it used minimal servos and equipment would indicate that the plane was not over-built or over-equipped.
You can't cure Stupid, Jim. If someone with little giant scale experience wants to read what I wrote and take it as a recommendation to set up all their planes like that and expect that it should work perfectly for them, then they deserve the fate of their plane.
12-07-2008, 10:04 AM
#99
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RE: Power Expander or not -that's the question
Nick,
You came on here and described a grossly insufficient set up, and told everyone that this set up flew fine at an invitational event, so obviously Power Expanders are not necessary. No, you didn't say that this set up was suitable for all conditions, but you didn't say that it wasn't either. You also didn't tell us all the facts involved with the set up. You just basically said here's a simple set up that worked fine.
What are people supposed to think? It sounded like a recommendation to me.
I guarantee you that guy was not getting proper current flow to his servos. I don't care who he was, the laws of physics work the same for everyone. A standard connector does not pass more current when flown at an invitational event, and neither does a standard HD switch.
I wouldn't use that set up on my glow planes! He might as well just use standard 40 in oz servos in his 42% plane, he'd get the same results.
This guy was asking for trouble.
Nobody should ever use a set up like that on a 42% airplane, even if "the plane was only 36 pounds and the geometry on the servos wasn't set up for 3D".
Not only was he risking his plane, he was also risking the safety of other pilots and spectators in the area.
At least now you've made it clear that it wasn't a recommendation, and that if anyone did use that set up they would be risking their plane.
Please don't anybody use a set up like that on a giant scale plane.
Jim
You came on here and described a grossly insufficient set up, and told everyone that this set up flew fine at an invitational event, so obviously Power Expanders are not necessary. No, you didn't say that this set up was suitable for all conditions, but you didn't say that it wasn't either. You also didn't tell us all the facts involved with the set up. You just basically said here's a simple set up that worked fine.
What are people supposed to think? It sounded like a recommendation to me.
I guarantee you that guy was not getting proper current flow to his servos. I don't care who he was, the laws of physics work the same for everyone. A standard connector does not pass more current when flown at an invitational event, and neither does a standard HD switch.
I wouldn't use that set up on my glow planes! He might as well just use standard 40 in oz servos in his 42% plane, he'd get the same results.
This guy was asking for trouble.
Nobody should ever use a set up like that on a 42% airplane, even if "the plane was only 36 pounds and the geometry on the servos wasn't set up for 3D".
Not only was he risking his plane, he was also risking the safety of other pilots and spectators in the area.
At least now you've made it clear that it wasn't a recommendation, and that if anyone did use that set up they would be risking their plane.
Please don't anybody use a set up like that on a giant scale plane.
Jim
12-07-2008, 10:15 AM
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RE: Power Expander or not -that's the question
I asked Smart Fly what it meant on their website when it says that their Power Expanders have "Long servo lead line matching". Here is the reply:
What that means is that we use a series resistor to help match the impedance
of the servo wires so that when the pulse is sent down the wire to
the servo there
is less ringing on the signal edge when it gets to the servo. This
reduces potential
interference from the servo wires.
So, here is yet another great feature of a Power Expander.
There is some compensation for long leads as far as the signal goes, but it does not compensate for voltage losses.
I had read somewhere else that Power Expanders did boost voltage in long leads, but it wasn't what I consider a reliable source, and I wasn't sure it was possible. Then I read that line on the Smart Fly website and got to wondering if it was somehow possible. It looks like it's not possible, but a Power Expander will help keep long lead voltage losses to a minimum by providing each servo with it's own power source (each servo plugs into it's own port on the Power Expander).
Jim
What that means is that we use a series resistor to help match the impedance
of the servo wires so that when the pulse is sent down the wire to
the servo there
is less ringing on the signal edge when it gets to the servo. This
reduces potential
interference from the servo wires.
So, here is yet another great feature of a Power Expander.
There is some compensation for long leads as far as the signal goes, but it does not compensate for voltage losses.
I had read somewhere else that Power Expanders did boost voltage in long leads, but it wasn't what I consider a reliable source, and I wasn't sure it was possible. Then I read that line on the Smart Fly website and got to wondering if it was somehow possible. It looks like it's not possible, but a Power Expander will help keep long lead voltage losses to a minimum by providing each servo with it's own power source (each servo plugs into it's own port on the Power Expander).
Jim