not sure if I should use one or two servo's on elevator
01-19-2002, 01:46 AM
#1
not sure if I should use one or two servo's on elevator
Need a jet mans opinion, building a topcat, and it uses one servo for the elevator, thought about splitting the elevator and using two 8411's instead of one just for safety sake if one goes bad maybe have enough elevator left to save it, dont want to loose it to a bad servo. What do you guys think? is the chance of one going bad rare? I dont want to crash it. Thats one more $100 servo, versus the possibility of saving the plane is worth that though, or am I thinking too much here?
Thanks, I appreciate the opinions.
Thanks, I appreciate the opinions.
01-19-2002, 07:24 AM
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REDUNDENT
JOHN,
if you have the space to do a clean instalation, a redundent elv. is a great thing, all of the yellow kits use two elv. servos and bvm also, your thinking of safety is right on the money !!
if you can get it in there, go for it .
regards, scott
yellow a/c
if you have the space to do a clean instalation, a redundent elv. is a great thing, all of the yellow kits use two elv. servos and bvm also, your thinking of safety is right on the money !!
if you can get it in there, go for it .
regards, scott
yellow a/c
01-19-2002, 07:48 AM
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not sure if I should use one or two servo's on elevator
John: I got 4 servoes on my Roo wing. Not that uncommon but there are others that do not. I did it for your same reason. Bkf
01-19-2002, 06:17 PM
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not sure if I should use one or two servo's on elevator
veiw one.
Twice the amount of servos equals twice as likely of a failure.
veiw two.
Twice the servos means you MAY be able to control it if on happens to fail close to the neutral position.
Someone needs to try a split elevator system on a Topcat and put one of the elevator servos on a mixer switch then we will know if it will work.Any volunteers?
jason
Twice the amount of servos equals twice as likely of a failure.
veiw two.
Twice the servos means you MAY be able to control it if on happens to fail close to the neutral position.
Someone needs to try a split elevator system on a Topcat and put one of the elevator servos on a mixer switch then we will know if it will work.Any volunteers?
jason
01-19-2002, 06:31 PM
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not sure if I should use one or two servo's on elevator
Jason: Perhaps what you say is true but one must think what the most common servo / control surface failures are. Usually striped gears, linkage failure, hinge failure, or control horn failure. All of which will let the failed surface float. Even in a worst case servo motor failure the forces on the surface would try to rotate the servo to a point where the force on the surface was less. Thats why they tell you not to move a servo using the surface by hand. There is alot of leverage there. Bkf
I probably will end up doing it.
01-20-2002, 03:31 AM
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not sure if I should use one or two servo's on elevator
Using more than one servo to power a surface is very common in giant scale planes. If you set it up right you should not have any binding issues.
01-20-2002, 06:20 PM
#12
not sure if I should use one or two servo's on elevator
John,
I'm pretty sure I'll be splitting the elevator on my Topcat also, as shown above. One could say there might be twice the chance of an elevator servo failing, but you could also say the chances of total loss of all elevator control is reduced to 25%, as opposed to using a single servo.
Now for the question: what servo torques to use? I would think 50-60 oz-in would be enough, per elevator side. I'll probably try that Multiplex torque calculator on their website...
I'm pretty sure I'll be splitting the elevator on my Topcat also, as shown above. One could say there might be twice the chance of an elevator servo failing, but you could also say the chances of total loss of all elevator control is reduced to 25%, as opposed to using a single servo.
Now for the question: what servo torques to use? I would think 50-60 oz-in would be enough, per elevator side. I'll probably try that Multiplex torque calculator on their website...
01-20-2002, 06:23 PM
#13
not sure if I should use one or two servo's on elevator
How about putting two 60-80 oz. digitals on a nonsplit elevator and running the new JR matchbox on it? That would cure the fighting and if one failed probably be enough servo there to get it back?
01-20-2002, 06:26 PM
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not sure if I should use one or two servo's on elevator
Take a look at the thread subject "10X Programming Question". This relates to the redundant elevator discussion. Comments are welcome.
