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Joined: 2/16/2007 From: Houston,
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SEBART KATANA 50E - FLIGHT REPORT
Ok, with a half healed thumb, and 20MPH wind gusts I coud not wait any longer and proceeded maiden flight.
I timed my flight for 6m30s, and commenced count down the moment I went hot with the radio and not the moment I began take off, i wanted to be using battery power for only that time for test purposes. (Timed from switch on to off).
Balanced at 122mm from leading edge could not go any further back with the battery which is kind of a bummer, I might have to get creative like remove the spinner or something I really wanted to go 130-135mm, Sebart recom. 130mm back for good 3D.
Checked flight control surfaces, I have 35 deg on high rate on all surfaces with 45% expo. I chose to do the maiden entirely on low rates. Which is set 40% of those values at the same expo rate. Cleared flight and went to crosshairs on the runway.
Take off was done with moderate parallel wind (10-12mph measured) with high gusts of 20-23mph. Throttle was applied slowly and absolutely no yaw coupling was necessary to keep the Katana straight as an arrow. When I reached half throttle the Katana began rotation and I pushed to about 3/4 throttle and began my crosswind leg, amazing tracking thus far . Downwind pass was done with the throttle reduced to half after adequate altitude was achieved for comfortable testing. The katana flew straight and level downwind and no trim was necessary, I was very very impressed. Came around on base leg, and during the first upwind pass one click of right aileron was required for staright and level flight at half throttle.
With trimming out of the way I began a series of aerobatic tests, and decided to throw my idea of doing all this on low rates out the window !! Rolls, inside & outside, axial and hell fast. Loops, power was steady and plentiful through all the maneuver, the big prop slowed it down nice coming down and out. Stalls, vertical and no wing drop noted. Snaps, inside & outside, up & down, were amazing the plane seemed to come loose during the snap and lock back up like two earth magnets whe you released the stick. These 4 snaps were done inverted as well, and same behavior was noted. No 3D was attempted during maiden flight.
THIS IS WHERE I NEED HELP, I have never encountered this before and I think I may know the culprit. I tried then to do a series of knife edge passes up and down wind. The moment I fed any amount of rudder in, the Katana would pull to the belly like I was putting a considerable amount of down elevator, but I wasnt it was the action caused by applying rudder in knife edge. I literally had to put very close to full up elevator on low rates to keep her straight, and with all that input during knife edge, it looks ugly!! So I thought at that time it would be perfect to test stall turns and hammerheads, SAME THING!! Everytime I apply rudder the plane doesnt pull, it YANKS to the belly. Even during straight and level flight, trying to test yaw authority causes it to descend and pull to the belly.
I think I could have possibly not have the motor stand-offs measured exactly. Or I may have to install a little up thrust into the motor standoffs. I have a digital incidence/throw meter and could accurately measure and adjust. But I dont know for sure that is where the problem could be. SOme guys at the field mentioned balancing but its balanced perfect, and flew that way as well.
When I heard the last minute alarm I landed the Katana with no incident, greased her in, went full crow, up with both ailerons, and elevators and slowed her down to a stop. Taxi is easy with full steering authority even in the gusty wind.
I removed the canopy and the battery was warm to the touch, and maybe even hot. But nothing that I would consider worrying about, I only went full throttle twice during the whole flight. I am most worried about the knife edge pulling to the belly than anything else.
** My test revealed I would definatlely like to change my battery, it seemed the power system had more in it, this flight stressed no part of the system all components were either warm or luke warm to the touch. I am going to remove my spinner to get the CG to move back a few MM. I want to move my BEC as far back as I can get it too help the CG as well. I am stuck on this knife edge problem though, Low Knife Edge passes are probably my favorite things to do Knife Edge Stalls, Knife Edge harriers, I love these show stoppers. And Im afraid of not being able to do them with this plane, im hoping modifying the standoffs will help me negate this issue....
< Message edited by aryajet -- 4/17/2008 7:10:38 PM >
Posts: 1504
Joined: 1/8/2002 From: Glendale,
AZ, USA Status: offline
Tail heavy will make it go to the belly. A tail heavy aircraft requires some down elevator to trim straight and level flight. Down elevator will cause it to go to the belly on KE. This is not the only cause but it is a factor. rudder can also just cause a plane to pitch to the gear, try a flat rudder turn with no elevator and see what happens. Now try it inverted and watch it climb.
Posts: 30
Joined: 2/16/2007 From: Houston,
TX, USA Status: offline
Hey man thanks a whole lot for the feedback. I am pretty sure I have a tail heavy airplane on my hands, because its overly sensitive on the controls and pitch motion is like a fishes tail (quick and snappy).
I am really excited to get it dialed in right, because even with a tail heavy condition it was still under control and relaxed. So set on point I can only imagine what a graceful flyer it can be. I am going to be getting that new aluminum balancer so I can do this with absolution.
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Joined: 1/15/2004 From: Kuala Lumpur, MALAYSIA Status: offline
Thanks a lot Amir ... how is the power on your plane, can she prop hang? I got the same motor for my plane but my batts will be EVO25 5S 4,900 ... she will be slightly heavier. Guess it will be ok for F3A flying. I am going with a 14x10 and then 15x10.
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Posts: 30
Joined: 2/16/2007 From: Houston,
TX, USA Status: offline
I meaured 9 lb 10 oz static thrust, with an AUW 6 lb 2 oz.
My batt is weak, and a cheapy. I bought 2 3S 3300 25C batt's that I plan to wire in a series. So it will be a 6S 3300 25C/50C burst. With that setup I plan to get 1 to 2 thrust ratio but it will prop hang at 3/4 the way it is now......
With your batt and prop you will get at a bare minimum 1 to 1.3 thrust ratio probably even more. Im guessing somewhere from 800-1000 watts but I might be mistaken. What ESC are you running?
Posts: 8159
Joined: 1/15/2004 From: Kuala Lumpur, MALAYSIA Status: offline
Amir ... you got over 9.5 lbs on your 5S set up? I put the watt meter on and I got 750W only on the 14x10. It was pulling 45A. I am using a cheap Himodel 120A, I will change it soon. I also have the AXI 4130/16 in my EP box of toys.
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SEBART KATANA 50E - FLIGHT REPORT - 
RE: KATANA 50E - FLIGHT REPORT - 
I am going with a 14x10 and then 15x10.