mithrandir
Posts: 742
Score: 100
Joined: 7/16/2003
Last Login: 3/16/2010
From: adelanto,
CA, USA
Status: offline
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Hidee ho there neighbors...
I have 30 flights on my KATANA , Got it from Chief, only cuz it is 3 days closer to me in california. I made the mods to the DEFECTIVE SPAR DESIGN. Basically framed around the tube with .125" spruce, and a piece of 1/32" aircraft ply pasted to the shear web (At a grain angle of plus'n'minus 45 degrees of course). When all done with servo, 15 oz/wing panel. Initially I thought it was gonna be tail heavy, I used pushrods and servos up front. Not easy thru little hole! OK... here are stats: OS 160, Bisson Pitts muffler, 20 oz tank, Futaba 9 ZAP with some fairly standard servos, one per ail, one per elev. I have tried the Mejzlik and APC 18 x 6 props, the APC was superior for me (3000 msl altitude). No mods other then the wing thing, and some pinning of the fire wall. I used the CA hinges through out and at flight 25, all but 1 rudder hinge failed!!! One hinge, and PULL-PULL cables were all that held it on!! ALSO... the cheesey tail wheel had to go... used a CG or Dubro tail wheel assy. The cheesey screws for the canopy and cowl never last for me, I simply taped the canopy, and installed blind/"T"-nuts for the cowling. A healthy soaking inside fuselage joints with CA was also done. Motor inverted with Perry pump. Pump is set to maximum pump, needle at about 1 turn (or in a little more) and I get... no kidding 26 minutes on that 20 oz tank!!! I do a lot of torque rolls and deep stalls at fractional power settings. Hovers at about 80% power @ 3000 Feet msl, at a take off weight of 12.6 pounds. (By the way, my YS 140 will not turn the APC 18 X 6 prop like the OS!!) I am still using the same plug as I broke it in with! 15% nitro fuel. Clearly as the fuel burns off and it gets lighter, it flies better! Will take about a pound out of GTOW and a half pound from MLW when I move battery back, (Take 4 oz from tail OUT) and put in a smaller tank, and prob'ly a lighter gear. The glass (Heavy, soon to be replaced) gear that comes with it is very STIFF!! Also, reinforce the cowl where the screws go thru it with a 1 inch square of CA Hinge material, this will prevent it from ovaling the hole!
OK... how does it fly???!!! Flies great, a couple of glitches though... There is just a touch of "ADVERSE ROLL" when rudder applied. A bit of pushing to the belly with rudder, both ways, easily mixed out thru normal flight regime. At HIGH RATE, HIGH BETA, (rudder deflected to point of hitting elevators) moderate power settings, I do not have enuff elevator to keep it from pitching nose down. Add power, and the nose will come back (Usually) OK.. the deep stall thing, it was a rocking SOB! Aft CG helped, a little. towards end of tank, not much better. OK... how did I fix this??? ZIG ZAG tape that they use on full size sailplane wings.!!! I placed this stuff at about 5% cord on top and bottom, from the tip inboard about 12 inches. HOLY SHEEP S%#T BATMAN.... a HUGE difference. I feel reasonably confident dragging it around at 45 degrees AOA at 30 feet above the ground! (Of course this little fix ruins this planes snap roll characteristics) No more doin 2 snaps on a vertical upline with this tape on it. This plane had a tendancy to snap out at just the right place in rolling circles too (I do it at 50% power... slow)... but the tape significantly reduced that.
One huge dissappointment though, I spoke with people at GSP and CA, both dealers basically denied any knowledge of the wings weakness. That was kinda CHICKEN S%#T. I of course got it anyway knowing the defect. Neither dealer would even imply that they were gonna fix this at the factory.
So basically I have rambled on here for a while, actually pleased with the plane, everything seems so light, 'cept the fuselage! This would be a real Humdinger at a GTOW of about 9 1/2 pounds!!! (10 1/2 would be great too!!) I would include a picture,... but we all know what it looks like!! LOL Well that is all I can think of saying, so have fun!!
PS. Simon, I got the "FUEL RETURN" idea from Perry, it was a miserable failure for me. I even tried a header tank, no good. But after flight 15 or so, it all gelled together and started to run GREAT, I don't know... Broke in finally?!?!? It has a totally even run through entire tank until last 3 teaspoons, then it gives me a little warning that it is time to land. I just used the pump in a normal manner. I have heard that there are some regulators out there that work better... no experiance there for me...
PPS... I also used very small Zip-Ties to secure all fuel lines to their respective nipples. I think I may also be a tad lean on the low end, takes a few seconds for the RPMs to finally drop to idle, but it is not running hot. I have the tank close to the CG, and 4 oz lead in tail, 600 mah nicad battery zip-tied to wing tube. Typically I will get 3 or 4, 13 to 16 minute flights with no indication of battery running low. Eventually I will move battery to rear and unload lead, (Just need free time right?!?) Actually it still flies nose heavy, I like'em to have a barely perceptable pull out in a dive test, this plane still pulls out a bit too much, and just a bit too much "TOP ELEVATOR" req'd whilst inverted.
mds
ZIG ZAG TAPE VENDOR- http://www.eglider.org/catalog/items/item296.htm
< Message edited by mithrandir -- 11/25/2003 5:06:54 AM >
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All Forums >> RC Airplanes >> ARF or RTF >> RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT 
RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 
RE: GSP Katana 72"...DETAILED BUILD and 3D FLIGHT REPORT - 
