Saturday, January 9, 2010

Easy Star Mark ][

Began work on the new FPV airframe (a new grey wing colored Multiplex Easy Star). One thing I really wanted to do, after learning a lot from the first one, was to put the elevator and rudder servos (Hitec HS-81's in this case) embedded in the tail section and to put most of the electronics in the fuselage beneath the wings. This should move the CoG back quite, which was needed for larger 3000+ maH LiPo in addition to the pan/tilt camera pod and to allow a lot more space for in the front hatch and (hopefully) clean up a lot of the massive amounts of wiring with the Eagle Tree Systems OSD Pro, eLogger, GPS, Altimeter, Mic and all the cabling daisy chained from the Rx to the OSD Pro for Return to Home (RtH) operation (sort of like autopilot when you lose radio contact).

Build Log
First, I got all the parts out and cleared some space on my work table to begin building the Easy Star II.



I began with cutting in the elevator and ruder servo holes into the tail portion of the fuselage.



Next, I began planning the cuts for the hatches in the bottom to open up the belly and cargo area where the bulk of the electronics would be fit as well as the receiver. I decided to keep the two pockets separate, for strength, and opened up two cargo hatches in the bottom.



It takes careful slicing away and matching up and slowly augering out the interior.



I beveled the cuts, so that when I got done, I could glue the pieces I removed together for the hatch cover and so that it would not push into the cavity. I also cut small notches in the cross braces of the center of the fuselage to run the tail mounted servo wires up through.



I also had planned to cut an air scoop in the front to help cool the lipo and electronics (seen here).



Finally, I glued the hatch pieces together, and put packing tape on one side to act like a hinge (after cutting a small finger hole out to make it easy to open). I also cut an exhaust hole to allow the air to push out of from the scoop in the front. Also, glued small rare earth magnets to the bottom of the fuse and the hatch covers so that they snap firmly in place and hold. I was actually very pleased with how strong and positive and seemless the hatches snap back into place.



Next, I began test fitting the OSD, eLogger, altitude sensor, microphone, and all the servo extensions from the OSD to the Rx, as well as the video and audio in/out feeds. I'll also have 2 tempsensors as well as one more batter monitor for the video batt and the GPS connection.



I put labels on the connectors, as it begins to quickly get messy and disorganized, especially once you pull stuff out later to refit. I also found I had to cut out more of the bracing between the bays to allow the OSD Pro to sit snuggly in there and pass all the cabling easily through to the forward bay, where I was placing the Rx.



Finally, with most of the test fitting of the electronics all done, and seeming like it was going to work ok. I went ahead and glued the two fuse halfs together and put the tail feathers on and connected the servos. I always have to trim the rudder up a little, because I don't get as much authority out of the elevator throw if I don't. I'm not planning to do anything with the rudder (a lot of folks put a larger one on for more turn authority, but with the aileron mod I'm planning, I never found a great need for more rudder control before). I am disappointed, however, after all these years, that they have not gone with a longer portion of the vertical stab being rudder (and making it about twice as deep on the surface).



Next was the motor and ESC. I had problems last time with the motor twisting in the motor mount, so I just put a drop of CA on the 3 points that touch the motor from the foam to hold it. I also cut a slight flat spot on the top to put the velcro that holds the ESC and cut a channel down the pod face for the wires to fit in with the canopy and/or the easy camera pod on.



While I still have to build the camera pod, put all the electronics in and get the aileron mods cut (as well as the GPS mounted in the wing), went ahead and got the wings finished, as well as magnets at the wing butt to hold them together (this really helped the old one, as the wing jig-saw fit gets loose after time). Also got the cockpit setup with just a tab at the front and rare earth magnets at the back, so either the canopy or the easy camera pod can fit on.



After putting the Rx, motor, 2600mAh 3S1P Lipo, and all the stuff for "basic" flight in, the CG is about half an inch too far to the back, even with the lipo all the way toward the front. Should be perfect once everything is in. AUW in this basic configuration is 26oz.



I am planning on putting some small wooden dowl/rods down the sides where the push rods were suppose to go (not carbon fiber rods, as those steal precious RF signal). I'm also not sure if I will try to fill in the original servo placement holes or not.

1 comment:

  1. Always a great job Jeff! Good Luck! Robert.

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