cptcrusty1

I have a sig Kobra kit that I'm over powering with a 46AX I have lying around. I'm using HS65 servos that are too tall to mounting standing up in the wing. I'd like to mount them sidways with the arm moving forward and backwards. I've seen custom mounts where the servo is mounted to a plate that gets screwed to the wing. but whatever can provided is VERY appreciated.

Please Please Please.... HELP!!!!


Crusty.

Campgems

Crusty they are so easy. Basicly you frame up a bay between the ribs with some hardwood or ply, making sure it is resesed 1/16" below the wing surface. Then you make a 1/16" ply hatch to fit. Cut you arm hole and the epoxy two hardwood mounts on the hatch. Cover, and mount your servo and you are done..

The first photo is of a mount I retrieved from a bad crash. You can see the remainder of the ribs on either side of the hardwood rails.

The second is the outside view. You can see the 1/16" recesses of the rails. I cap the rails that run lengthwise with 1/16" balsa to complete a smooth frame.

The next shows the servo lugs. I use a little piece of a cracker box or like thickness between the servo and the lugs to make sure the servo has some wiggle room on the mounts.

Next is the hatch setting in the frame waiting for mounting screws.

The last is with a servo mounted.

I like the Dubro #2 sheet metal scrws, with the socket screw head. #254 if memory serves me right. They provide a low profile streamline head. Don't know if it helps with the aerodynamics but it looks goodl

Don

cptcrusty1

Are the rails mounted with epoxy only or do you use screws to hold it in place...

foodstick

Campgems, I hope you didn't rip those out of the plane just for this tutorial ! )

Good pictures though, much easier than writing it all out.

Campgems

Just 5 minute epoxy

Don

ByLoudDesign

Campgems
That is a cool mount, even if your servo and link stay completly with in the wing those mounting blocks could be longer. Nice way to be able to service or change the servo, plus when scratch building and find the servo over powered you could upgrade to a larger one if it fits through the hole!
Charlie

Campgems

Actually the plate with the servo came from my 4*60 that bit the dust on Saturday. I loved that plane. It was my second.

The other photos were from my Evolution (made up name) It started life as an Lanair Explor 40 trainer. I found that I was having aileron issues and my instructor kept telling me to ease up on the sticks. Turns out that there was no bearing tubes on the aileron torque rods so I cut the rods off and built my first set of servo boxes. Crashed the trainer destroying the fuselage but leaving the wings and tail intact. built a stick tail dragger out of the left overs and loved that plane. Lost it in the creek bed behind the field where it lay for over four months. I had a spare set of wings for the Explorer so I built another fuselage and awaay I went. One of the guys was trying to teach me inverted and I ended putting the plane at full throttle into the deer fence destroying the wing. From there I built a new wing with the same airfoil as the 4*60. That was a great flying plane until "the crash" which put my O.S. 52 four stroke into a pile of broken parts. The first photos with out servos are from that plane.

On a hard crash, sometimes you will snap off one of th lugs, but I've never had one come loose my it's self.

One thing that isn't obvious in the photos is that I sand a 45 around the lugs and then after gettting them epoxied but before it hardend I flow a bead of epoxy and fliet it around the base. It spreads the load further up on the lugs and further out on the plate.

Don

ByLoudDesign

Cool, Don!

Campgems

Oun of our guys used something similuar for the rudder and elevator servos on his four star. He took the cut out from the lightneing hole and set it up with the long lugs and the arms just barrely exit the fuselage. Very clean.

I like to keep the servo arm center line as close to the wing surface as possible. That lets me use maximum throw on the servo without the linkage fowling in the cutout.


Don

cptcrusty1

OK. here's a stupid question. I build the mounts, make them nice a pretty. Even mom would like them. But they are essentially holes in the wing.. is air going to get in there and cause the wing to fill like a balloon, or do you do something to keep that from happing?

Campgems

Well, when the wing blows up enouth that they pop, you get to cover them with a diffenent color that you really wanted in the first place

Joking aside, the wings don't fillup like a ballon. Rember that airflow over a surface results in a drop in pressure which translates to lift. There isn't going to be a build up pressure in the wings, but rather a vacuum. If there was a hole in the leading edge that could ram the air into the wing, it may cause some balloning. Seeing as the servo arm exits are well back from the spars, this just isn't going to hapen.

Don