Tuesday, June 5, 2012

Needle 100 DSL assembly Part 2

Wing servo installation:

Upon recommendation from Thuro, I switched to the DS6125 glider instead of the the DS6125 mini. I had a small trouble during the installation because the horn location of the ailerons was too much within the servo bay location (1cm). I had to open the servo bay a bit more. This is not a big issue, easy to fix, and which doesn't affect the robustness or thiffness of the wing.

at Order, there is the choice between normal control horn and DS control horn. The last ones are longer, so installation is a bit different. I choose the DS horns. They are CNC milled in epoxy board, and the hole is exactly at the right dimension to avoid any command slop. I carefully followed Thuro's instructions. After doing the holes at the exact place in the wing skin, I glued the epoxy control horns with the command in place. I used rapid epoxy (10 minutes) from R&G as I'm very satisfied with it. I added some micro balloon in it.

Then, this the servo arm at the right position, and the right neutral shift programmed on the tramsitter program, I glued the MKS wood servo frames in place, with the servo connected to the control command. I used aluminium servo arms, drilled at the right diameter, paying attention to have absolutely no slop again.

Aside, I prepared the wiring using MPX green connectors. Despite using the MKS SBEC in the wings, I calculated the wire length without taking it into account., in order to make the SBEC accessible, or be able to run without the SBEC.

The green connector is glued in place in the root of the wing, with the wing connected to the fuselage, where the connector is already installed and glued. I used Polyvinyl Alcohol Release Agent to be sure that the 2 connectors won't glued together as it happened once.

After fixin the servos on the servoframe with screws, I used transparent servo covers from Samba Model that allow a quick preflight checking, and wich is very convenient from my point of view for maintenance.

Fuselage installation completion

I needed 250g of lead to obtain the rigth balance with a CoG at 86/87mm. Hopefully the nose is long enough to host the lead (melted at the right shape), The LiFe battery, the RG631B  DMSS 6 channel JR receiver with its satellite, and the Zepsus magnetic switch.

Empty flying weight is 2600gr, which is above the expected weight, but given the usage of the plane (DS and strong condition flying) it is not worrying me.

I'm also very happy with the wing servo commands and epoxy horns. There is absolutely no slop at all, and I have the deflection I needed, using the whole servo arm rotation. I agree that the epoxy horn and command is a bit visible on the upper side of the wing, but this is the price to pay for an efficient and robust command.

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