Are DS8411SA's OK in Gas Planes
01-01-2006, 01:30 PM
#1
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Are DS8411SA's OK in Gas Planes
Hello Danny,
For the last few seasons I have been using DS8411SA Digital servos in my 2 metre F3A competition aircraft. I have been very pleased with their performance and have found that the hybrid metal/resin gearbox gives a noticeably tighter deadband than the alloy gearbox in the standard DS 8411. That of course is one of the reasons why JR marketed the Special Application version in the first place!
For reasons of standardisation, I am keen to use DS 8411 SA’s in one of my larger 28% gasoline powered 3-D aerobatic airframes. In terms of torque requirement there ought not to be a problem. The specified requirement is for servos with a minimum torque of 100 oz in, and with both the DS 8411 and the DS8411SA being rated at 155 oz in there ought to be enough in hand.
However I have noticed that many manufacturers of 33% (and even 28%) gas powered models make a point of recommending servos with metal gearboxes. I can only assume that this is to offer more protection against the possibility of gears stripping due to control surface flutter (although interestingly, the standard DS8411 – in common with many metal geared servos from other manufacturers – includes a “sacrificial” nylon gear within the gear train!)
I should be grateful for any advice or experience that you might have to offer on the subject.
Many thanks
AA
For the last few seasons I have been using DS8411SA Digital servos in my 2 metre F3A competition aircraft. I have been very pleased with their performance and have found that the hybrid metal/resin gearbox gives a noticeably tighter deadband than the alloy gearbox in the standard DS 8411. That of course is one of the reasons why JR marketed the Special Application version in the first place!
For reasons of standardisation, I am keen to use DS 8411 SA’s in one of my larger 28% gasoline powered 3-D aerobatic airframes. In terms of torque requirement there ought not to be a problem. The specified requirement is for servos with a minimum torque of 100 oz in, and with both the DS 8411 and the DS8411SA being rated at 155 oz in there ought to be enough in hand.
However I have noticed that many manufacturers of 33% (and even 28%) gas powered models make a point of recommending servos with metal gearboxes. I can only assume that this is to offer more protection against the possibility of gears stripping due to control surface flutter (although interestingly, the standard DS8411 – in common with many metal geared servos from other manufacturers – includes a “sacrificial” nylon gear within the gear train!)
I should be grateful for any advice or experience that you might have to offer on the subject.
Many thanks
AA
01-04-2006, 10:26 AM
#2
RE: Are DS8411SA's OK in Gas Planes
The 8411SA is only recommended for up to 1.20 size models, the high torque of the servo combined with higher flight loads can lead to stripping of the servo gears. In the case of the metal geared servos, they must have a nylon gear in the gear train to prevent RF in the servo motor from being transmitted through the gear train, which would cause RF issues. The nylon gear is the first gear that meshes with the motor pinion and as such takes the least amount of shock of any of the gears in the servo.
