To reduce the loads on
the nose gear and the airplane it is important that the wheel can
move
a long distance up and backwards when it meets some resistance.
The nose gear described here is designed by me and I have used it,
with success, on two small EDF models.
First J35J DRAKEN made by
Shenzhen E-Do Model Co.
Then I built a similar retractable gear for Durafly D.H. 100 Vampire MK 6.
Gear design
The
body consists of two collars and a brass tube soldered together to
one unit.
The wheel is mounted on a piano wire bent i both ends and is fixed
with a collar.
The bent part in the other end of the wire goes thru a bras
tube serving as a bearing.
The wheel is hold in its down position by a coil spring around the
brass tube.
Bill of material
1.4
pcs Stop collars with 3 mm hole and 7 mm diameter. 2.1
pcs Brass tube with 2 mm hole, 3 mm diameter and 18 mm long. 3.1
pcs Piano wire for the gear and the stop pin with 2 mm diameter. 4.1
pcs Piano wire for the coil spring with 1 or 1.5 mm diameter,
depending on the desired stiffness. 5.1
pcs Stop washer of steel with 2 mm hole.
6. 1 pcs Wheel with 2 mm hole.
Building instructions
Two
stop collars and the brass tube are soldered together. Soldering
should be done with silver solder to get sufficient
strength.
Grind the parts smooth to get a good joint.
Use iron wire to hold the part in place during soldering. See the
picture below.
Flux and a gas flame completes the soldering.
The coil spring is twisted around an axis with 3 mm diameter (
e.g. a drill steel).
Notice that it should be twisted in different directions depending
on how the gear can be mounted and retracted in the plane.
Bend the piano wire to fit the wheel and the brass tube.
The part that goes thru the brass tube and the stop collar is
about 25 mm long.
Solder the stop washer to the piano wire.
Drill a hole for the stop pin in the collar and solder it in
place. Mount the parts to a complete nose gear.
