redundancy yes.....no..?
02-10-2005, 03:49 PM
#76
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RE: redundancy yes.....no..?
Those who bash ENGINEERS are often the TECHNICIANS who think they are always fixing engineers' f*kups. What they don't realize is that their are many more typical reasons a design fails than engineering imcompetency. Walk a mile in our shoes and you might begin to appreciate the CRAP we engineers have to deal with. Many of our problems aren't even technical ones. To wit, a few exmaples:
1. Sales sells a product before we even begin designing it.
2. Manufacturing fabricates products not exactly as engineering specified.
3. QC accepts "equivalent" part that aren't exactly equivalent, or just as bad, put a non-conformance on an item because it's a different shade of orange paint.
4. Field operations performs non-standard repairs or maintenance, and doesn't tell us about it.
5. Field operations buys "equivalent" parts, because it's 50 cents cheaper than ordering out of stock, and then *****es to engineering when the thing don't work.
6. Finally, two words: Upper Management. Need I say more?
Unfortunately for your technicians, sh*t flows downhill and you are near the bottom.[
]
1. Sales sells a product before we even begin designing it.
2. Manufacturing fabricates products not exactly as engineering specified.
3. QC accepts "equivalent" part that aren't exactly equivalent, or just as bad, put a non-conformance on an item because it's a different shade of orange paint.
4. Field operations performs non-standard repairs or maintenance, and doesn't tell us about it.
5. Field operations buys "equivalent" parts, because it's 50 cents cheaper than ordering out of stock, and then *****es to engineering when the thing don't work.
6. Finally, two words: Upper Management. Need I say more?
Unfortunately for your technicians, sh*t flows downhill and you are near the bottom.[
]
02-11-2005, 01:59 AM
#78
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RE: redundancy yes.....no..?
Ok i'm gonna start by saying I run a single receiver, two batts, two switches. I like to keep it simple, my preference....I do see a couple of discrepacies in all these posts: I'm not sure redundency is what everyone is talking about here. some are talking about true redundancy, (back up systems) and some are talking about two completely separate systems operating within the same plane. I agree that the true redundant systems add uneeded complexity to the plane, thus adding systems that have more weak links to fail. with two separate systems, you do have twice the equipment to fail, but one system does not effect the other and I'd like to say that the chances of both individual systems failing, other than rf interferance, are nil.
02-11-2005, 10:47 AM
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RE: redundancy yes.....no..?
ORIGINAL: Ryans Rebel
Volfy,
Sound like you work in the oilfield!
Volfy,
Sound like you work in the oilfield!
Stayed at the Comfort Inn(?) in New Iberia when I did field testing of a prototype choke system at a rig near Erath a couple of years ago. The rig took a kick and was blowing gas out to a flare pit WITH NO FLARES, and the rig was surrounded by cane fields where the farmers were burning harvest leftovers. Talk about pucker factor.
Anyhow, back on topic. Here is a product that does let you do true RX redundancy:
http://www.rc-electronic.com/html/en...dpsi_twin.html
Personally, I think the value of this kind of setup is dubious at best, as the vast majority of RX "failures" are caused by human error (e.g. some bonehead turninng on his TX on the same channel). Nevertheless, as ARFs get bigger and more expensive, folks will be more inclined to buy insurance, whether it's actually worth it or there just to make the owner sleep better at night.
02-11-2005, 11:10 AM
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RE: redundancy yes.....no..?
ORIGINAL: Volfy
Anyhow, back on topic. Here is a product that does let you do true RX redundancy:
http://www.rc-electronic.com/html/en...dpsi_twin.html
Personally, I think the value of this kind of setup is dubious at best, as the vast majority of RX "failures" are caused by human error (e.g. some bonehead turninng on his TX on the same channel). Nevertheless, as ARFs get bigger and more expensive, folks will be more inclined to buy insurance, whether it's actually worth it or there just to make the owner sleep better at night.
Anyhow, back on topic. Here is a product that does let you do true RX redundancy:
http://www.rc-electronic.com/html/en...dpsi_twin.html
Personally, I think the value of this kind of setup is dubious at best, as the vast majority of RX "failures" are caused by human error (e.g. some bonehead turninng on his TX on the same channel). Nevertheless, as ARFs get bigger and more expensive, folks will be more inclined to buy insurance, whether it's actually worth it or there just to make the owner sleep better at night.
DITTO whay Volfy says!
02-11-2005, 12:44 PM
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RE: redundancy yes.....no..?
I would also agree with VOLFLY that the comfort factor is the main reason that many people try to make redundant systems.
With very few exceptions, The primary mode of failure is almost never identified in model crashes. We go for the obvious or the pundits position. I have seen as many linkage and mechanical failures as I have seen electrical and electronic failures yet we don't go for redundant pushrods and control horns.
I do use multiple switches on battery packs simply because I do not vibration isolate every switch. I also use Battery isolators and separate receiver packs on large servo installations simply to insure a stable power supply to the receiver.
As for dual receiver installations I do run them in large scale planes but as separate systems controlling different parts of the aircraft. Balancing a 30# wing center section with my forhead while trying to hook up fuselage servo extensions and retract hoses doesn't work for me anymore.[8D]
With very few exceptions, The primary mode of failure is almost never identified in model crashes. We go for the obvious or the pundits position. I have seen as many linkage and mechanical failures as I have seen electrical and electronic failures yet we don't go for redundant pushrods and control horns.
I do use multiple switches on battery packs simply because I do not vibration isolate every switch. I also use Battery isolators and separate receiver packs on large servo installations simply to insure a stable power supply to the receiver.
As for dual receiver installations I do run them in large scale planes but as separate systems controlling different parts of the aircraft. Balancing a 30# wing center section with my forhead while trying to hook up fuselage servo extensions and retract hoses doesn't work for me anymore.[8D]
11-09-2005, 10:02 AM
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RE: redundancy yes.....no..?
ORIGINAL: branded
I'm an engineer for a major aerospace defense contractor and I can tell you that redundancy in a RC system detracts from the reliability of the system.
Redundancy only makes sense where there is automated decision making as in onboard computer control systems (as used on high tech "fly by wire" aircraft fighters) whereby the redundant systems poll each other and act on the result of the majority.
Running redundant wiring, dual; recievers, etc. only adds to the unreliabilty of the system by adding complexity and more components that can fail without the benefit of decision making.
I'm an engineer for a major aerospace defense contractor and I can tell you that redundancy in a RC system detracts from the reliability of the system.
Redundancy only makes sense where there is automated decision making as in onboard computer control systems (as used on high tech "fly by wire" aircraft fighters) whereby the redundant systems poll each other and act on the result of the majority.
Running redundant wiring, dual; recievers, etc. only adds to the unreliabilty of the system by adding complexity and more components that can fail without the benefit of decision making.
11-09-2005, 06:45 PM
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RE: redundancy yes.....no..?
Hi,
You can minimize the chance for failure:
1) dual batteries, dual switches with a single rx.
2) shrink wrap all connections
3) cycle batteries, check between flights
OR
You can plan for failure:
1) dual rxs with complete separate systems. When one side fails, you can usually land the plane either safely or in a controlled crash to minimize damage. I have done this numerous times with research planes which fly frequent and long flights
AND
You can use all of the techniques to minimize failure when you assemble your dual systems so you can both minimize failure and plan for failure.
Hope this helps to clarify
Elson
You can minimize the chance for failure:
1) dual batteries, dual switches with a single rx.
2) shrink wrap all connections
3) cycle batteries, check between flights
OR
You can plan for failure:
1) dual rxs with complete separate systems. When one side fails, you can usually land the plane either safely or in a controlled crash to minimize damage. I have done this numerous times with research planes which fly frequent and long flights
AND
You can use all of the techniques to minimize failure when you assemble your dual systems so you can both minimize failure and plan for failure.
Hope this helps to clarify
Elson
