GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT
Thanks. I know the post is long...I'm sure it's my longest yet. Perhaps it should have been titled 'Too much coffee'.
Now to answer your questions:
1. No extra nose weight was required to get it to balance near the aft recommended CG. IMHO, people who are adding nose weight or moving the servos amidships to get the CG in the recommended range are doing the airframe a great injustice...my CG is still too far forward for my liking. I consider any CG recommendation to be just that...it's not a 'limit'. You gotta fly the plane to find the sweet spot. I spend the first ten or so flights of any plane working on setup (CG, mixing, thrust line, etc.). If you spend the time on the planes it will show...if you don't it will show. Too many people think the work is done after the first successful flight. To me it's just beginning...
2. The wing tube is 30mm. Finding an off the shelf CF tube might be tough. I considered making one but don't think it would be worth the trouble. Maybe later...
3. The CF tube I used is roughly the same diameter as the anti rotation pins. The CF tube extends all the way through the fuselage whereas the pins only penetrate part way. When you build it you'll know what I'm talking about.
4. You can make a tool from music wire to hook the springs. The tool should be long enough to go all the way through the fuselage, hook onto the spring, then you can pull the spring tight. After I pull one spring through the fuselage I use 1/8" bamboo skewers to temporarily hold it in place while I'm stretching the other spring through the fuselage. I stick another skewer through the other spring, slide the wing on, then stretch the springs over the eyebolts. Works OK but I think I'm going to opt for another set of bolts to hold the wing to the fuse and do away with the springs altogether. I could save a few ounces this way and I'm sure that it would be strong enough...plus the springs are a pain.
5. A top-access hatch would be nice but I didn't feel like putting the effort in. The small hatch provides enough room to get to the servo leads and wing bolts.
6. I'm sure the covering on mine is just as good (or bad) as everyone elses. I'm very picky on the things I BUILD but not very picky about the things I ASSEMBLE.
7. I hate to say this but if you have to 'Y' the servos together it sounds like you could benefit from a better transmitter...like a JR 8103DT. It's tough to recommend servos. Use the best ones that you can afford. I'm sure that you could get away with HS605s all the way around, but they don't center well and aren't nearly as powerful or fast as the HS5925s or S9402s even though the specs will tell you that they are. Feed the servos with 6V for extra punch.
My fingertips are bruised...
-Tom