E-Flight Airliner Retract Project

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Page 4

       To mount the nose gear to the support plate I decided to drill out three of the four screw holes in the retract mechanism. I removed three of the existing bolts in the case and then drilled straight through the case with an 1/8” drill bit. Notice I left the bottom left screw in place to hold the case together.

       I now could lay out where the gear would sit on the support plate. I moved the gear 32 mm forward from it’s original location so the nose wheel will clear the battery hatch when retracted. The retract case is placed 3 mm back from the forward side of the plate as well as 11 mm from the bottom left corner of the plate. The retract unit is squared up with the left side of the plate as shown below. Do not run the gear parallel with the bottom of the plate or the gear will not extend straight.

       I used a vise to help hold the retract unit in place while I drilled the holes in the plate for the hardware.

       I used a set of 4-40 X 30 mm cap screws and blind nuts to mount the retract unit to the support plate. Once the blind nuts were set, I cut off the excess screw length and sanded the surface flush. A small amount of thin CA glue was used to cement the ends of the screws in place.

       A wider hole needed to be cut into the fuse To allow for the new retract unit. I started out by cutting the hole 10 mm wide but would eventually cut it out to 35 mm as seen later in the photos.

       The original nose wheel had a ride height of 115 mm from the wheel to the bottom of the fuse at the strut. Luckily the nose strut did not need to be trimmed to meet this dimension. However the nose wheel used a much smaller gear wire than the mains so the strut needed to be drilled out to 1/8”. Be sure to remove the set screw before attempting to drill out the strut.

       Once again I needed to fabricate a shaft to mount the strut to so I cut a 45 mm long shaft out of the nose gear wire.

       I ground some flat spots on the nose gear strut shaft as I did the main gear shafts. Using the “set screw mark” method is the best way of laying out the places to grind flat spots on the shaft.

       I installed the shaft into the retract unit and used some blue threadlocker to seal the deal.

       The nose gear was soon to follow. Notice the steering arm is parallel to the wheel axle.

       I could now cut out the gear bay in the fuse. I used a small sanding drum to cut away the trough where the gear strut will lay when retracted. Once again with a little patients you can achieve great results by taking your time.

       I will be using the HS-81MG for the nose gear retract. They are amazingly powerful and only weigh 0.67 oz. I decided to get a preliminary CG on the jet before I continued to mount the servo. I placed the HS-81 servo on top of the jet at the battery hatch while I measured the center of gravity.

       Surprisingly the CG was right on with the servo close to the nose. This will make the install of the nose gear servo easy as it will not require a long linkage to move the servo back closer to the CG.

       I chose to mount the servo just in front of the battery bay for easy access. A plywood mounting plate was made for the HS-81 out of 1/8” birch ply. It measures 62 mm wide by 32 mm high. A couple of hardwood blocks were made to support the servo in the middle of the plate.

       The top of the servo case is set flush with the top of the plywood plate.

       A couple pieces of 1/2” angle stock was used as gussets for the plate. They were glued to the plate 40 mm apart with the flat sides facing outward.

       To glue the plate into the jet I used 30 minute epoxy with microballoons as before. The plate mounts so the bottom is flush with the “bottom” of the foam support pillars at the front of the battery bay as shown below.

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