OlyII Spoiler installation

[Mike K]

Hello, everyone.

I'm probably obsessing over this a little bit too much, so I'd like some feedback.

I'm to the point on my OlyII wings where I need to install the servos for the spoilers.

I've been looking at various techniques people have used for a while. I really liked the ball link method used on the Ava, but as my transmitter is an old AM Futaba, I thought that this would be very difficult to get adjusted right as the two servos will be on a Y-harness.

A second option, mounting the servos onto the spoilers... They won't fit.

The next option is a simple one - Use a small magnet to hold them shut, then a small piece of wire to raise them up. Much easier to adjust, I think.
The issue being, every installation I have seen so far has had the servo so that the wheel is perpendicular to the wing. (Think servo motor parallel to wing span.) I don't think I can do it this way as the servo wheel would be too far back to raise the spoiler more than 1/4th of an inch.

So the next option is to turn the servos 90 degrees, so the wheel is parallel to the span. I can easily get the spoiler raised up to 60 or 75 degrees this way. The pressure is mostly down on the servo wheel though. I don't have any idea if this would be ok or not...

Thoughts?

Thanks in advance!

Mike K.

[rogerflies]

How about using the strings like the plans show? That always worked well for me after I installed the small (almost-touching) magnets to hold the spoilers closed.

Using the strings puts the servo forward of the CG, and that'll save you some weight.

If you're dead set on using a servo in the wing, why not use an arm instead of a wheel? Just cut off the parts you don't need. Note that some of the servo arms aren't the same angle with respect to the splines. You'll have to play around with them to get the exact same travel on both spoilers.

Roger

[OVSS Boss]

Make a torque tube, small music wire inside an aluminum tube, that is in the leading edge of the spoiler and that keeps it down. Then no linkage is needed from the servo, all the servo has to do is have arm contact and it will push the spoiler up and the torque tube will bring it down when the servo moves down, I will post pics later.

Marc

[jrgospod]

Mike K

I found this in a resent RCSE post and am planning on trying it. It looks easy and has positive open and close, which I like.

John

http://www.git-r-built.com/newsmgr/templates/grbNews.asp?articleid=29&zoneid=1

[OVSS Boss]

OK guys, the pics are not pretty, neither is the build, but it shows what I did. In the upper leading edge of the spoiler, is an aluminum tube holding a very fine wire bent in a "U" shape that the tube is the bottom ot the "U", you can see the tube. The tube is mounted in the upper leading edge of the spoiler with one end of the wire in the spoiler and the other in a tube that is mounted in the servo mounting plate. You can see this tube to the left of the first pic. This assembly keeps the spoiler down unless the spoiler servo "pushes" it up. The second pic just shows the servo in contact with the spoiler and and pushing it up into the open position. Ray Hayes can vouch for the install and it's effectice spoiler control. This wing is from a Grand Esprit and it allows for a very controlled deployment.

Marc

[trident58]

Marc,
That's a sweet setup! I've been agonizing over what to use in the spoilers on my Durex, but I think I'll try your method. Thanks for the idea!
Jon

[Mike K]

Make a torque tube, small music wire inside an aluminum tube, that is in the leading edge of the spoiler and that keeps it down. Then no linkage is needed from the servo, all the servo has to do is have arm contact and it will push the spoiler up and the torque tube will bring it down when the servo moves down, I will post pics later.

Marc

Keeping the spoiler down isn't the problem. The problem is that, as I have the spoilers set as per the plans that come with the kit, I cannot fit an HS-81 far enough forward to allow the servo arm to clear the rear of the spoiler. Even if I were to cut the plastic mounting point off the front side, I'd still need to cut out the balsa shear web to fit it in properly.

Somehow, I picture the wings folding... This isn't a pretty sight...

Since I cannot fit the servo in this way, my option was to rotate the servo 90 degrees. On the ground, this works fine. I don't see there being a problem with the force involved, hence my question here. I've got a couple of ideas I think would really work well...

I guess my second option is to move the entire assembly back from the spar about half an inch. That might be more work initially, but it would seem to be more in line with ever single other spoiler installation I've seen.

Regards.
Mike Kirda

[jrgospod]

Mike,

According to some of the experts I have seen on RCGROUPS, RCSE, and YAHOO groups it is better to have your spoilers farther back in the cord if it will work. Something about the air flow not being disturbed as soon and generating more lift. That said I would not do the extra work of moving them after they are installed. I also would not do anything to weaken the spar. If the servos give you enough deflection positioned at 90 degrees, then it should be ok. I have set them in at 45 degrees before and not had a problem. Your other choice would be to get different servos that would fit and save the HS-81s for another project.

John

[OVSS Boss]

Mike,
The HS81 is over kill for the spoiler, I have some Cirrus something in the Grand and it is a larger spoiler than the Oly has. Also, I think that you should have more thickness in the wing in the Oly too, so as John pointed out, save the 81's and find some other finer servo for the job.

Marc