60" Molded racers for MoM

[Konrad]

Well, I think I recovered from this fiasco. I need to give a shout out to Doc. for encouraging me to try these epoxy wipers.

Servorahmen IDS servo mounts etc - step by step install?

As to filler is it cabosil, or milled fiber? I see the spoon supporting the front of the control surface like a shear web. I'm concerned with the hole, or lack of continuity, in the sub spar of the wing itself in which the push rod travels. P.S. Sorry I see the you clearly state the sub spar...

forum.alofthobbies.com

While far from perfect, I’m actually happy with the results. In fact I like this hinge more than the OEM flex hinge we get with the elevator.
Double sided interrupted wipers are not what I would recommend as a starting point for a first time attempt! I used the method where one uses tape as the carrier for the epoxy. I think that the use of a 1.5mil mylar would have given better results. But as there was so much going on trying to work around the hinge pins I choose tape.

While it didn't take a lot of man hours, it did take 4 days to accomplish, as one needs to wait for the curing of epoxy during each step.


Wow, those photos are horrible!! I need to try again after a cup of tea.
(new photos are only a bit better)

All the best,
Konrad

 

[Wayne]

No, no no.. You need to show the steps. I have never done these and would love to see how you did them.

 

[Konrad]

Sorry, I really didn’t take any in process photos, as the video in the link earlier really did a great job of describing the process.

Now the issue I had was with the Robart pinned hinges. Getting the axis of both pins aligned is an art! That is why I only used 2 pins! They are the large steel pinned hinges so I’m sure they are up to the task. I had some concerns with the stability of the hinge but I used a lot of epoxy to support the barbs against the fin and rudder skins.

The key to this rudder was epoxying in a nut to allow the control horn to thread into. And to make a seal on each side of the rudder. This takes time as one needs to wait for the one side to cure before doing the other side.
The fact that there are hinges in the way made it difficult to control the epoxy. I didn’t want the epoxy the hinges motionless. To that end I used silicon oil to lube the pivot pins prior to glueing the hinges into the fin.

The secret is to do one thing at a time! Glue the nut into the rudder. Glue the two hinges into the fin with the pivots aligned. Let cure. Add fillet to the hinge barb and vertical fin skin. Glue rudder onto hinges with a bit too much glue. You want a good rudder to hinge bond. Let cure. Tape up wiper and add epoxy per the video. Flip tape under the fin. But leave the surface flexed open while still allowing the tape end to be under the skin. When the epoxy has set (3hours) cut the wiper for clearance of the hinges in the wiper (notches). Let cure. Repeat for the second side. Then admire your work, and thumb your nose at the OEM for such poor documentation!

 

[Konrad]

I just got back from a visit to Aloft and have to say I'm rather pleased how well my ad hoc rudder hinge repair looks against some of the other professional builders hinge lines.

You can see some waviness in the wiper. If I had used stiffer mylar I think I could have corrected this. I also had my knife slip when I first made the cuts for the rudder.

 

[Konrad]

Earlier in this thread (post #4)Wayne showed a nice green Dart III. You might notice that the fuselage to stab joint is very nice. Now my red Dart III shows this void at the fuse to stab intersection. What I’d like to ask is; are you guys having to raise the stab’s LE to get the most out of your Dart III? Is this why the current mold has this void? Or is it just wear in the mold and I should just fill it in?
TIA,

 

[Wayne]

Fly it first and see how she does. We only got a couple of these Darts in and I think at least one has flown and I don't recall any issues with it. But I'd fly it first before doing any filling.

 

[Konrad]

At the April 20th MOM 60" race I was asking those that had this fuselage (under various names) if they changed the stab incident. Most said that they had raising the LE of the stab.

 

[Konrad]

What is wrong with this picture? A $10 servo in an $15 servo frame!

It is no secret that I like the PDI-0902MG servo, love the PDI-HV0903MG. I’ve also recently become enamored with servo trays with external bearing support.
By chance I noticed that the splines of the PDI servo match the splines of the KST XO-8 servo. So this got me thinking!

Well not a perfect fit the servo tray for the KST X0-8 can be made to work with the PDI servo.

JX PDI-0902MG Servo - 2.6 Kg (36.11 oz in), .07 sec - High Voltage

Digital control, high torque and a metal gear train make this servo an attractive choice but the thin profile (8mm) is really where it shines. A great servo for lighter gliders, thermal ships, and entry level DLG's at a great price.

alofthobbies.com

IDS KST X08 Mono

The Integrated Drive System, aka IDS is the cutting edge method for mounting wing servos in high performance aircraft. The servo trays have an outboard ball bearing that helps to carry the servo shaft loads and greatly reduces servo play. The result? Gr

alofthobbies.com

All the best,
Konrad

 

[Wayne]

LOL - That is great.