Dave,

good to hear that you've been making progress. I look forward to the picture updates.

Yea, the suggested servos, the Spektrum A5030's, are very popular and great mini servo's. In fact, they seemed to be unavailable anywhere for the entire time you mention. They were sold out for good reason, they have excellent specs and perform well. I'm glad they finally came in as it means that Spektrum must have produced a new batch and hopefully they will be widely available again. Spektrum has also been expanding their line of servos with HV versions of the existing ones and a few new ones. There is now an A5060 as well which is an impressive mini servo (albeit at 3 times the retail price), which can put out 118 oz in of torque when powered on 2s lipo's. Transit time is still 0.11 sec/60 degrees. These servos are excellent candidates for even rudders on 60-120 size classics. I'll probably try one on the rudder of my next 60 size build.

Another pretty good servo in the mini class, at least on paper, is the Tactic TSX25. It is also a mini servo slightly larger and heavier than the A5030 but it produces a great deal of torque, north of 90 oz in, at 6V. They are a tad slower than the Spektrum's but still pretty fast compared to many others in the mini category. I have purchased 5 of them to try out in a 50 or 60 size classic. I'll have further info once I receive them and check them out. By the way, these servos are all coreless, dual ball bearing digital servos.

Just quickly you mentioned 3040's which are also a Spektrum servo but they are micro metal gear servos. Any of the 3000 series servos (4 of them) would be well suited for carburetor controls, retract valves and steering of nose gears but don't use them on control surfaces of 40 size models. I wouldn't use them on the controls of 25 size models either (the 4000 series are there for that). They can be used on controls of foamy's and maybe 10-15 size classic glow models with narrow controls. I'd consider using them on ailerons of such a model but would still go with 4000's on the tail.

Speaking of ailerons, there are basically two ways I do individual aileron servo installations - either the servo is mounted upright with the servo wheel exposed on the surface of the wing bottom or the servo is side mounted so a servo arm protrudes through a hatch also mounted between rib bays on the underside. On the DB40 I suggested mounting the servos upright against the inside of rib R5. This puts the servo and control horn roughly at 1/3 of the aileron span and right beside a hinge - take a look at the plans for reference. What I usually do is cut a couple of lengths of 1/4" (or 3/8") square hardwood wide enough to span the servo width. The plans show rails that are 9/16" long. I then mark the rails for the servo holes to be drilled positioning the servo in the middle. Once mounted on the rails, I cut two rectangular pieces of 3/32" (or 1/8") balsa with their bases flush with the servo bottom. They are width sized to span the length of the servo and rail assembly and I generally cut them oversize height wise so the servo wheel needs to be removed when framing up the balsa box. With the two sides glued to the servo rails and level on a table top with the servo bottom, you can then cap the ends with more 3/32" balsa cut from the same length used for the sides. I keep the grain vertical so its easy to cut the sides. Finally, I usually also cap off the bottom of the pocket, primarily as it keeps the pocket square and gives it more strength. The entire pocket can be sanded smooth once glued up.

The servo pocket then gets glued up against a wing rib and against the spar shear web on the back of the spars (see plans). Unless the spar is square with the ribs (e.g., in a Kaos), you need to sand the front of the pocket at an angle so that it mates well against the shear web. In order to provide some material for sanding to an angle, I typically add another piece of 3/32" balsa to the front of the pocket or simply built up the front piece with 3/16" scrap - whatever scrap wood you have for these pockets does the trick.

Last but not least, I glue the pockets in so that the servo wheel is almost flush with the wing sheeting. Actually, placing it so the wheel is 1/8" higher than the rib works well. This allows for the 1/16" sheeting plus another 1/16" for the clevis attachment of the pushrod. The more concealed the servos the better. Mounting the servos laterally is more work and requires more material but is also a tad more elegant as it conceals the servo entirely leaving only the arm protruding from a slot in the 1/16" mounting plate. I tend to prefer the vertically mounted approach as it allows tthe servo to be installed/removed easily and doesn't require additional hardware and exposed screws to mount the plates to the wing. It really comes down to personal preference though. Both work equally well.

I have some pictures of the vertical mount somewhere but I can't seem to locate them. I might just take some others to post.

I hope this helps.

David