I was wondering if it is normal for 8411s to have a lot of slop when they are new? I installed them in the ailerons and connected them to the RX. With the power on the servo allows the trailing edge of the aileron to move almost 1/8" both ways. The 8611s on the flaps allow almost no movement. Is this normal for these servos? Will it get worse?

BTW I tried two 8411s with the same results.

None with the ones I used...the linkage is tight, right?

There is slop inherent in the gear lash of most metal geared servos, but this is magnified by a poor geometry setup. Most jets do not have good pushrod geometry as standard due to the desire to hide linkages. Use the shortest servo arm coupled to the longest control horn you can stand that will give you the throw you need and not one degree more. This should be done with the ATV's up around 135-140%.

Thanks I will try some different arm geometries.

Kenny,
Doug is correct however.... What he has failed to mention is the 8411 has inherently more gear slop than most metal geared servos. I have never found this additional slop to be an issue with flight control or performance.
It is important to optimize the likage geometry to reduce the play....
Todd

I have been using a program to help me do just what these guys are saying

The program helps calculate the linkage angles as well as the torque required at any given airspeed.

I have just been doing an elevator that requires 1.125" up/1" down travel...pretty typical. But I wanted the maximum servo travel. Turns out an 8611 can be driven about 58 to 60 degrees give or take in each direction. I feed that into my program and I can play with the arm lengths to get it right. Now the servo travels to its extreme limits to get the required surface throw

I also got rid of clevises, I rarely use them now except for pull-pull installs that do not have linkage slop in the traditional sense. I use helicopter ball links and dubro large ball links on almost everything else.

Kenny did you get a second turbine for your F-18 yet?

i changed all my 8411 servos to the SA gears. around $5 gets you 2 sets of tight gears (not metal)



Wojtek

KFalcon,
what you can do is pack the 8411 with white lithium grease - no more slop - servo feels as tight as a hydraulic actuator.

Jackjet

How can we get this program Mr. Matt?

http://members.cox.net/evdesign/page...ge_design.html


Believe me this is worth the money

Thank you all for it input.

Matt, That program is neat. No I don't have the second P-120 yet. I am still looking and fighting what seems to be a losing battle for the money. Tell Bob you need one for a good cause and I will pay $500 a week... Keep your eyes open for me.

You do need to be careful doing this.. The 8411SA (what you basically get by changing the gears) is NOT designed for very high stress uses. With the original 8411, you'll stall the servo before any damage. With the 8411SA it's actually possible to fail the gears before the motor stalls.

Need to be careful with this too.... The extra grease can make the gear train to tight causing excessive current draw from the servo....

Adding some grease will help the slop though?

Todd I just read the e-mails you company sent me about the status of my order. It is nice that it will e-mail you every time there is a change in status. I don't usually order from the internet with out talking to someone but you system kicks *****.

Hey Kenny,
Yes, grease will help eliminate some of the slop by filling the gap between the gear mesh. You have to be careful with this though. I did some experiments using the in-line amp meter and can see some noticeable increase in current draw if too much is added. With all the 8411's I have installed, I have yet to have any issues related to the slight play created by 8411 gear mesh. Once under flight load the play is a non issue (assuming you have the correct linkage geometry). If your really worried about the play, use 8611's instead .
I appreciate the feedback about the site. We all like to know what the status of our orders are, and we usually want the items asap. I felt it was important to integrate an order status update into my system to notify you as your order progresses through to shipped status. I always like to hear feedback from my customers, if there is anything I can do to improve the product or the website please let me know . Thanks for the order....
Regards,
Todd

I tried but they are to big to fit in the aileron spot. I don't care about the slop as long as it doesn't effect the flight characteristics. Thanks for the input guys.

Kenny,

What little slop there is will not be noticed really. 1/8" each way seems excessive though.. Did you find any way to change the geometry of the setup? Let me know when you and Joe are going to fly it and I'll come up and help out with anything I can JR related.

Doug,

I haven't tried yet but I will let you know as soon as I do.

I will definitely let you know when we go! There is a lot of JR firsts for me in this thing (Match Box, servo Xpander etc.) and I will definitely appreciate the help!