Apr 10, 2011, 09:40 AM
United States, GA, Valdosta
Joined Jan 2009
Okay a little behind...lets see if I can catch up today!
Finished the build last night. Overall a fairly straight-forward sequence but there were a few snags, mostly related to the business end of the plane.
You will need spacers to move the motor 3/16" to 1/4" forward. Plywood rings come with the kit but I haven't had much luck with them as they tend to compress even when given a generous coat of thin CA. My favorite spacers for this are 1/4" x .140 x 1/4" nylon spacers from Hillman...available at Lowes. These fit over the M3 hex screws nicely and are very light weight. You will need M3 screws at least 15mm long too.
The cowl will need to be shimmed on the right side (left side looking at the plane) in order to get the spinner aligned with the opening. I used three M3 washers on each of the two cowl screws to get a near perfect fit. I was a bit skeptical about the hidden cowl mounting system but, it worked out fine...tight work area with my big ol' biscuit hooks.
Hand thread the wing bolts into the wings first! You will want to do this a few times minimum to get the nylon wing bolts ready. I tried to tread them with the wings on the plane and almost cross threaded them!
With my setup 1/3 of the FlightMax 2650 battery was on the wing tube to get her to balance! This turned out to be a non issue for flight because the velcro mounted on the battery and wing tube, along with the battery strap, held it in place very well. Also, the fuselage and canopy framing is open enough to allow the battery to stick up into the canopy somewhat.
The published flying weight range is 1300g to 1600g My AUW is 1636g/3.6 lbs. I don't see how the 1300g weight is even remotely possible! Here is a list of added weight due to my equipment:
IceLite 75A instead of Atlas 60A = +3g
Metal geared servos = +4g
2650 FlightMax (313 actual) instead of Hyperion 2600 VX (273 published) = +40g
Total = 47g/1.7 oz heavier than recommended set-up.
Balance point is at 100mm (published range 95 -105 mm) behind wing root/fuselage point. This puts it right at the center of the wing tube. Installing the ESC near the wing tube would help with moving the battery off of the wing tube and onto the battery tray. However doing this would mean making motor wire extensions. I've read somewhere that extending the motor wires a little is better than extending the battery connection wires...I welcome comments from someone who can confirm or deny this!
The cowl has somewhat small openings for cooling and no method of directing air onto the motor or ESC. After my maiden flight the motor was very warm.
I chose not to use the links provided with the kit and instead went with all ball joint hardware and M2 fully treaded rod. Wing and elevator rods are 45mm long while the rudder rod is 62mm long. I had to search the internet to find the M2 rod but given that I had lots of 2mm ball joint connectors from other kits I thought the effort was worth it. Dubro makes 2mm ball joint connectors that are much better than the kit hardware in my opinion. I looked at switching over to the 2-56 connectors but with all the planes coming from China, thus being metric, it made sense to stick with metric.
Seeing the max current amp numbers (65A) for the motor on the Hyperion web site I decided to go with a IceLite 75. I drilled small holes in the base of the motor cage far enough apart to let me run a strip of velcro for the battery between them on the inside of the cage/battery box. This also enabled me to locate the zip ties away from the critical parts of the controller. As you've seen in the issues section above, I may very will move the ESC to be on the CG location.
I believe the plane could be lightened somewhat. Using the current weight of my plane, 3.6 lbs, 722 watts would give one 200w/lb. With that number in mind, I believe the following configuration would work:
800W motor: Scorpion 3020-780 (166g/5.8 oz) = -31g
50A ESC: IceLite 50 (48g/1.7 oz.) = -20g
2200 30C 4s: FlightMax 2200 (268g/9.4oz.) = -44g
Total = 95g/3.3 oz. less or .2 lbs. New weight 3.4 lbs. or 680 watts @ 200W/lb. 800W motor would be 235W/lb.
Is it worth all that? I don't know...I was very anxious about the weight when I took her up for her maiden but those fears were quickly put to rest once she left the ground! One click of left aileron and one click of down elevator proved to be all she needed for straight and level flight. She flew great during the 6 minute initial shakedown and will head uphill like she was kicked in the rear! 100mm is a good balance point. I'll post amp/volt/watt numbers soon.
I'm going to fly again this afternoon and may have some video...we don't have a video camera proper but will try some with my Wife's new camera on video mode to see how it does. Pictures coming ...
Last edited by daedalusrobert; Apr 10, 2011 at 02:29 PM.