Guess this is a stupid question but how many degrees should a std servo travel? On my HS55 i've got +-19 degrees, is this normal?

The reason why i ask is that i need 13.5 mm servo travel for retracts, and with the included servo arm (25mm long) i only get 8mm.


//Hans

Most servos are capable of 60 deg full travel rotation. You'll probably need a retract servo for your retracts. The rotation of a retract servo is about 180 deg.

This is a retract from GWS that only needs 13.5 mm travel, sure a HS55 should be able to manage that?

its not all about the amount of travel when you use retract servos there is positive up and down locking, without loading your battery and running it down during flight, the amount of travel can be adjusted in the servo arm as you know, I am surprised you are getting so little travel from your servo, check your end point adjustment for your retract channel some radios have power on power off for this channel, depends on your set up you should be getting more travel.
it sucks having to spend 30$$ on retract servos but you will be better off for it

Dooh, 38 deg was only in one direction [sm=red_smile.gif] with 125% travel (max). I have a Hitec Optic 6 and want to use the HFS-05MS rx, can i use this for retracts? The rx only have ch1, 2 ,3 ,4 and ch6. I dont want to use any rudder so ch4 is available for retracts, can i use ch4 for retracts or must i use the dedicated ch5 as decribed in the manual?

For these retracts i want the servo to be in one of the max end positions and should travel all the way to the other end position with a switch on the tx, is this possible?


//Hans

Hans you need to use the dedicated channel 1-4 channels are proportional yes? meaning they can travel the same as the sticks are moved and let me repeat my self with a standard servo you do not have positive locking, as far as I know without battery drain.
positive lock means that when the servo is finished moving it is in a locked position so the gear doesn't fold on landing standard servos do not have this feature so user beware.
coming for a landing and having your gear fold on you sucks and can damage or destroy a plane pretty quick.

Bigtim, thanks for replying. This is from the GWS site:

Do you have any experience with the GWS retracts. Of course there is nothing to hold the retracts up so i guess i will drain the battery a bit?

/Hans

no I don't know those in particular, I have 2 Hangar9 mechanical retract models and even though they also have a locking feature in the retract system.
I still would be ultra cautious with battery drain possibility make sure there is no chance of a loss of control from battery running down, sounds like you are dead set on using the servos on hand, I personally would not use them, but thats for me to decide.
I have a ARF Hangar9 mustang on hold waiting for a retract servo so you know where my personal position is.I use Robart and Century jet air retracts on my kit built warbirds so servo operated units I have limited knowledge, but I have read allot of information and have some idea of what I am telling you, and am just passing it along

Hans

I will assuse with a hs55 as a retract servo this is a park flyer? The optic 6 should have channel mixing or programable mixes. Set channel 5 as master and channel 6 as slave should work ok. If you need more servo travel than the arm will give extend the arm with some thin plywood. I hope this makes sense.

A retract gear that locks is one thing.
A retract servo is another thing.

Most retract gears are designed so that when the gear is fully opened or fully closed, the strut is held and supported by the structure of the mechanism. No effort is needed on the pushrods to resist the force of landing nor to hold the strut/wheel up in the wheelwell. When the gear is up, there is no load on the pushrods. When the gear is down, there is no load on the pushrods.

Retract servo's are designed so that when the servo arm is at either end of it's travel, the servo motor is "turned off." That way, the servo is not constantly working to hold the gear down or up. It only works to move it. That saves constant drain on the battery. When the servo is all the way "up" it will not draw from the battery. When it is all the way "down" it won't draw.

The problem you have with a standard servo, even with good retract mechanism design, is that unless the linkage is adjusted perfectly a standard servo will feel a load and fight it. If the linkage is too long and pushes or pulls the retract unit past either "at rest" location, the standard servo will work and work and work and drain the battery. If the linkage is too short etc etc

however...................

however..........

Most non-digital servos draw less current at their center point. So if you've got to use a standard servo for gear retraction, you can use that design feature for a slight advantage.

Center the servo for gear up. Then keep the airplane turned off except when actually in use. And of course, don't use a digital servo.

I am not that up on Servo's and servo travel, but there is a gizmo sold as advertized here on RCU. The gizmo is called TXServo. It connects the servo's to a computer controlled testing program that will exercize servo's through their entire span of rotation. I tried a couple different types on this thing and got pretty mucn 180 degrees of movement out of them both. The device is reasonable (price wise) because it includes the software to test with.

Anyway, I was having problems with one of my servo's used on the throttle of a fuel plane. I could not get what I thought was full throw out of this thing so that I had to use mechanical adjustments to get full throttle movement with the servo only rotating about 40 degrees. One of the guys at the field recognized the problem and we worked through it by resetting the throw of the servo which included centering, and so on. I did not write down the procedure, nor do I remember the process, but can certainly find out what he did so I can pass it on.

Basically, it re-set the transmitter for servo throw, end points, centering, and so on, so that full servo action was achieved. This may be what you need to do.

Did you 'copy' a model for a multiple model memory transmitter? If so, you may have done exactly what I did and simply need to reset that channel for full throttle throw.

Someone on here may know the process, and may post it, but, as I said, I don't exactly remember the process so I cannot relate it to you.

Hope this helps a bit.

DS.