What's the biggest plane you'd run Nylon geared servo's?
04-28-2007, 10:41 AM
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What's the biggest plane you'd run Nylon geared servo's?
I am just wondering what the biggest plane most people would still run high torque nylon geared servos on? The reason I ask, is I remember not too long ago, all our big planes were flown with 50oz, nylon geared servos. It seems today, anything over a .90 size plane and companies start demanding high torque mg servos. I understand that is in part to the huge control surfaces 3D planes have now. Opinions?
04-28-2007, 12:05 PM
#2
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RE: What's the biggest plane you'd run Nylon geared servo's?
The question seems loaded but … I am using standard servos for aileron control on a 22-pound airplane (92†span) but boost tabs are also used. The roll rate is less than desired but can probably be attributed to the design of the airplane.
Bill
Bill
04-28-2007, 10:48 PM
#4
RE: What's the biggest plane you'd run Nylon geared servo's?
It depends on what application. I would use nylon geared servo's on a large scale piper cub but for a 3D machine I would not used nylon on anything bigger than 23%ish
04-29-2007, 07:14 AM
#7
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RE: What's the biggest plane you'd run Nylon geared servo's?
Nylon geared servos come in many different forms and therefore there is no absolute rule about using them or not using them. I would stay away from Carbonite gears in any high vibration situation though.
04-29-2007, 09:41 AM
#8
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RE: What's the biggest plane you'd run Nylon geared servo's?
I have been running a Phaeton 90 with a Quadra 72cc engine with all nylon geared servos for over seven years, no problems with gears and all Futaba servos.
04-29-2007, 11:22 AM
#9
RE: What's the biggest plane you'd run Nylon geared servo's?
you could have asked "why use stronger gears"
that is the real issue
the servo guys typically make the gear trains strong enough for their servos to work reliably up to 6V inputs (modern servos )
so if you reach out and stall a servo at 6 volts (not a good idea ) the servo will stop but not break the gears . the small micro/mini servos ar not as forgiving by the way.
The rush to 3D stuf called for long servo arms and lots of models ended up with -you guessed it - stalled servos at end points and stalled servos from airloads exceeding the servo output
lots of these simply up n died -
the metal geartrains usually have one or more nylon gears but the idea was to strengthen the last gears and output shaft to accept the ABUSE from metal arms with offset ball links and all sorts of really bad geometry.
The filled nylon gears such as Hi Teck and some others use are a mixed blessing - used correctly - good gears --
so if you are flying a larger model which is subject to being banged into the ground and or has large control surfaces which have a lot of inertia when banged or hit --expect to break gears or use metal gear trains.
what size model needs metal gears??
you are going to have to make an informed decision based on yourr own use and ability.
the price of metal gear trains is dropping so price is not a real issue now
One more thing -depending on the type of battery pack you use - you may /may not have increased the serovo output to the point that the gears simply can't push back the motor under high current .
that is the real issue
the servo guys typically make the gear trains strong enough for their servos to work reliably up to 6V inputs (modern servos )
so if you reach out and stall a servo at 6 volts (not a good idea ) the servo will stop but not break the gears . the small micro/mini servos ar not as forgiving by the way.
The rush to 3D stuf called for long servo arms and lots of models ended up with -you guessed it - stalled servos at end points and stalled servos from airloads exceeding the servo output
lots of these simply up n died -
the metal geartrains usually have one or more nylon gears but the idea was to strengthen the last gears and output shaft to accept the ABUSE from metal arms with offset ball links and all sorts of really bad geometry.
The filled nylon gears such as Hi Teck and some others use are a mixed blessing - used correctly - good gears --
so if you are flying a larger model which is subject to being banged into the ground and or has large control surfaces which have a lot of inertia when banged or hit --expect to break gears or use metal gear trains.
what size model needs metal gears??
you are going to have to make an informed decision based on yourr own use and ability.
the price of metal gear trains is dropping so price is not a real issue now
One more thing -depending on the type of battery pack you use - you may /may not have increased the serovo output to the point that the gears simply can't push back the motor under high current .
04-30-2007, 02:29 PM
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RE: What's the biggest plane you'd run Nylon geared servo's?
Wow, thank you Dick, that was very informative. I am asking because I have been using JR 821 digital servo's for quite some time now, and have ended up with alot of them, mainly because people were selling them very cheap when they bought their DX7 systems. I put a complete set in a 13 pound scratchbuilt Ultimate and they have worked out great. Now, I have a 12 pound Cap that I plan on flying on the fairly aggresive side, and am wondering if I am going to push those servo's too far.
ORIGINAL: dick Hanson
you could have asked "why use stronger gears"
that is the real issue
the servo guys typically make the gear trains strong enough for their servos to work reliably up to 6V inputs (modern servos )
so if you reach out and stall a servo at 6 volts (not a good idea ) the servo will stop but not break the gears . the small micro/mini servos ar not as forgiving by the way.
The rush to 3D stuf called for long servo arms and lots of models ended up with -you guessed it - stalled servos at end points and stalled servos from airloads exceeding the servo output
lots of these simply up n died -
the metal geartrains usually have one or more nylon gears but the idea was to strengthen the last gears and output shaft to accept the ABUSE from metal arms with offset ball links and all sorts of really bad geometry.
The filled nylon gears such as Hi Teck and some others use are a mixed blessing - used correctly - good gears --
so if you are flying a larger model which is subject to being banged into the ground and or has large control surfaces which have a lot of inertia when banged or hit --expect to break gears or use metal gear trains.
what size model needs metal gears??
you are going to have to make an informed decision based on yourr own use and ability.
the price of metal gear trains is dropping so price is not a real issue now
One more thing -depending on the type of battery pack you use - you may /may not have increased the serovo output to the point that the gears simply can't push back the motor under high current .
you could have asked "why use stronger gears"
that is the real issue
the servo guys typically make the gear trains strong enough for their servos to work reliably up to 6V inputs (modern servos )
so if you reach out and stall a servo at 6 volts (not a good idea ) the servo will stop but not break the gears . the small micro/mini servos ar not as forgiving by the way.
The rush to 3D stuf called for long servo arms and lots of models ended up with -you guessed it - stalled servos at end points and stalled servos from airloads exceeding the servo output
lots of these simply up n died -
the metal geartrains usually have one or more nylon gears but the idea was to strengthen the last gears and output shaft to accept the ABUSE from metal arms with offset ball links and all sorts of really bad geometry.
The filled nylon gears such as Hi Teck and some others use are a mixed blessing - used correctly - good gears --
so if you are flying a larger model which is subject to being banged into the ground and or has large control surfaces which have a lot of inertia when banged or hit --expect to break gears or use metal gear trains.
what size model needs metal gears??
you are going to have to make an informed decision based on yourr own use and ability.
the price of metal gear trains is dropping so price is not a real issue now
One more thing -depending on the type of battery pack you use - you may /may not have increased the serovo output to the point that the gears simply can't push back the motor under high current .
04-30-2007, 02:56 PM
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RE: What's the biggest plane you'd run Nylon geared servo's?
Nylon gears per se are not the full issue. More to the point is whether a specific servo model is up to the application. Servos like the Seiko put out 24 ft lbs of torque(4608 oz in) through a nylon gear train with no gear stripping.
Gears are just one of many things that can cause servo failure. Mounting servos with the case in a strain and using connections on the output arms that produce couples put heavy loads on both the top bearing and the output gear. anything that works to force the gears out of proper mesh will serve to create tooth failure as quickly as heavy loads will.
Gears are just one of many things that can cause servo failure. Mounting servos with the case in a strain and using connections on the output arms that produce couples put heavy loads on both the top bearing and the output gear. anything that works to force the gears out of proper mesh will serve to create tooth failure as quickly as heavy loads will.
04-30-2007, 03:23 PM
#12
RE: What's the biggest plane you'd run Nylon geared servo's?
I would stay away from Carbonite gears in any high vibration situation though.
I have been using Hitec 6965 s on the tail control of two of my helicopters without any trouble. And we all know how shaky some helicopters are.
Rafael
