Receiver: Hitec 555
Servos: Hitec HS-81
Transmitter: Futaba 6XAS
The EZ400G requires a larger landing area than planes like the Slow Stick. Despite what the NSP web site says you need to land fairly fast - if you slow down too much the EZ will stall and drop a metre or two.
It is possible that your pylon may fall to pieces under stress without strengenthing being added to the pylon. See rcgroups for details.
My suggested modification is as follows:
- Add a section of 12mm triangle section balsa to join the top plate of the pylon to the pylon side.
- Add vertical strips of hardwood down the side of the pylon.
This photo shows the repaired pylon with the additional strengthening. In addition this shows the Apitek camera mount and camera switch installed on the EZ400G.
The EZ400G motor mount consists of an oval piece of fibreglass with an appropriate hole and mounting points for the MPjet gearbox. This must be mounted onto the carbon fibre tube that is the fuselage. During the mounting procedure the appropriate thrust adjustments are built in.
It is somewhat tricky to get this mount to stay attached and to avoid it ripping of with the motor torque, especially with brushless motors.
My method of attaching this mount is described here, along with some examples of mounting various brushless motors.
Standard Motor and gearbox
This is the standard S400 motor as viewed from the front, with the motor removed from the gearbox and only one of the three mounting screw installed. Points to note:
- There are two 0.75mm music wire pegs that go through the timber mount support and stop the fibreglass mount from tearing itself free of the timber.
- There is one 0.75mm music wire peg vertically through the timber mount and also through the carbon fibre tube. This wire is visible as it goes through the centre of the tube. Note: this plane has been repaired and a 5.5mm tube glued inside the standard tube to repair a damaged outer tube.
- There are two ventilation holes bored through the gearbox to provide ventilation to the motor. The motor is put into the gearbox from the rear and oriented so that the holes in the front of the motor line up with those bored in the gearbox.
When viewed from the top you can see:
- The wire peg that attaches the timber mount support to the tube.
- The right thrust that has been build into the timber mount support. The down thrust is also sanded onto the timber mount support so that the fibreglass mount is attached to the mount support and this provides the thrust adjustment
The side view shows:
- The timber block at the rear of motor. This small block is filed and sanded to provide two appropriate angled grooves for the carbon fibre tube and the bottom of the motor. It is also slightly beveled to match the down thrust angle.
- A wire tie that is used to tie the rear of the motor down to the timber support and the carbon tube.
AXI 2212/26 brushless outrunner
The AXI is mounted using it's radial mount kit to a plywood mount adapter. The AXI standard mounting was made difficult by the timber mount support being in front of the fibreglass mount. The problem is that if the AXI is mounted it is 'normal' manner the prop is not sufficiently clear of the end of the carbon fibre tube.
A possible solution to this problem is to make the timber mount adapter so that it attaches behind the fibreglass motor mount. One detrimental effect of this change would be that the timber mount support no longer serves as an stop to keep the fibreglass motor mount on the tube. My experience is that one advantage of the mount as shown is that in the event of the motor mount breaking free, the timber mount support keeps the mount on the tube rather than the motor breaking free and flying off the front of the aircraft.
The AXI mount was also made so that the AXI was interchangeable with the other motors shown here - no additional mounting holes or other changes to the standard EZ motor mount were desired.
- The ply mount is cut so that it rests flush on the top of the timber mount support and then cut to the same shape as the oval support. Being flush with the timber mount helps transfer the torque to the timber support directly, rather than twisting the fibreglass mount off the support.
- Ventilation holes for the motor are drilled through the plywood mount, these open through the hole already cut in the fibreglass mount.
MPjet 25/35-20 brushless with 4:1 gearbox
This motor will fit onto the mount as supplied because the MPjet gearbox mounts are identical. However, the torque of the motor makes it easy to rip the mount off. The wire pins shown and described above were included in the mount to keep this motor attached. The standard motor, and the AXI, will mount without problems with the wire pins missing.
- Two rings of heatshrink tubing were used to increase the diameter of the plastic motor mount so that it was the same size as the S400 gearbox. This serves to keep the gearbox located and held by the circular gearbox cutout.
- In a similar manner to the standard motor mount a timber motor support and wire tie are used to attach the motor to the carbon tube.
The EZ400G wing is of light weight construction and there have been a number of reports of the wing folding, or breaking. See these two rcgroups threads for details. http://www.rcgroups.com/forums/showthread.php?t=258266 http://www.rcgroups.com/forums/showthread.php?t=260933
The commonly agreed solution to improve the strength of the wing, especially to twisting forces, is to add shear webs to the central section of the wing. Shear webs are sections of balsa sheet, with their grain running vertically, that fit tightly between the wing ribs and the top and bottom spars.
The following procedure, courtesy of Ironsides, explains how to add shear webs to your EZ400G wing. You will need:
- A sharp hobby knife
- A metal square and ruler
- A sheet of 2.4mm balsa (75mm wide is sufficient, you will need about 250mm)
- A sanding block (a piece of sand paper taped to a flat piece of timber)
- PVA wood glue
- one small and one slightly larger paint brush
- A small piece of covering material
The procedure is:
Step Description 1 Remove the wing covering material from the underside of the wing between the leading edge and the spar. Do this by running a sharp knife through the covering film on the back of the leading edge and then along the front of the spar and then down each side of the section. The covering should then come off. Save the piece of covering for measuring the replacement covering later on. 2 Now cut a piece of 2.4mm balsa with the grain running vertically that is just larger that the space between the ribs and the outside edge of the spars to fit into the first space. On my EZ400G wing 26mm high and 70mm wide was just the right size to start with. 3 Sand the sides of this piece of balsa until it is exactly the right size to fit into the first space. Use the sanding block so that you get nice straight sides. If you end up sanding a bit too much off a piece of balsa try one of the other spaces along the wing, they are not all exactly the same size. Make sure that the pieces of balsa do not stick out on the lower edge, this will ensure that the covering goes back on easily. 4 Repeat the above procedure to make a piece of balsa to fit each of the gaps between the ribs. Note that each piece will be a slightly different size, so leave each piece in the wing once you have it the right size. Eventually you will have all the shear webs cut and sanded to the correct size and sitting in the wing. 5 Now remove one of the balsa pieces and place it on the work space so you can replaced it into the wing exactly the same way it was originally. 6 Using a small brush paint the leading face of the top and bottom spars with PVA wood glue. Also paint a strip of glue along the ribs just in front of the two spars. 7 Put the piece of balsa back into the wing and gently press it down along the spars. If you look in through the wing covering you should see a small bead of PVA glue between the shear web and the spars and along the ribs. Wipe off any glue that is pushed out between the web and the underside spar, this will ensure that there is no glue to sand off when you get to the covering stage.
Repeat this procedure until you have glued in all the shear webs.
8 Wait 24 hours for the glue to dry properly. 9 Now make a mixture of PVA wood glue and a little water to make the glue more into a thick house paint consistency. Using a medium brush apply the PVA and water mixture all over the shear webs and also to the ribs where the webs meet the ribs. This step adds strength to the whole assembly. 10 Wait 24 hours for the glue to dry properly. 11 Now check that the webs do not sick out of the wing further than the underside spar. If they do then gently sand the webs back so that the covering will fit properly.
If the existing covering film is dirty clean the film and then wait to ensure it is completely dry. If you left the sticky tape on the joins between the flat wing section and the tip sections you will need to remove it where the covering will be attached.
12 Using the piece of covering that you removed in the first step cut a piece of new covering material that is 10mm larger all round. 13 Using a covering iron tack the new covering in place at each corner then along the edges, then shrink it in place and finally trim and seal the edges to complete the recovering.
With any luck you will get a better covering than this photo shows.
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