Help with my new Katana 46  
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All Forums >> RC Airplanes >> Profile and Fun Flying Planes >> OMP - Ohio Model Products Support Forum >> Help with my new Katana 46
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Help with my new Katana 46 - 5/30/2007 3:30:06 AM   
gipper6


 

Posts: 42
Joined: 8/19/2005
From: DFW, TX, USA
Status: offline 		At idle throttle, this things drops like a rock nose first. I balanced it per the instructions @ 5 1/4 from the wing root. Is it too nose heavy or is this the way they fly? Help.

< Message edited by gipper6 -- 5/30/2007 3:45:06 AM >
       Post #: 1

RE: Help with my new Katana 46 - 5/30/2007 11:37:46 PM   
skukreja


 

Posts: 264
Joined: 8/14/2004
From: Chicago, IL, USA
Status: offline 		i can fly mine slow.. but it's true of all profiles vs. conventional fuses... you won't generate quite as much lift with a profile and yes, they will stall like any other plane..

(in reply to gipper6)
       Post #: 2

RE: Help with my new Katana 46 - 5/31/2007 12:13:14 AM   
gipper6


 

Posts: 42
Joined: 8/19/2005
From: DFW, TX, USA
Status: offline 		I can fly it at slow speeds also, but when it's time to land I either add power or nose dive. Is that normal with profiles?

(in reply to skukreja)
       Post #: 3

RE: Help with my new Katana 46 - 5/31/2007 12:51:02 PM   
southern_touch9


 

Posts: 1549
Joined: 7/11/2003
From: Columbus, GA, USA
Status: offline 		My Katana never did that. I could come in at a crawl. It always landed best to line it up with zero throttle and at about 5 ft add a little a milk the landing.

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Layne Minor

(in reply to gipper6)
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RE: Help with my new Katana 46 - 5/31/2007 12:53:48 PM   
AFSalmon



Posts: 3822
Joined: 5/24/2002
From: Beavercreek, OH,
Status: offline 		Gipper, I answered your PM with the same question but to sum up here most likely your engine thrust line is off. Probably pointing up which creates climbing when under power and diving when power is off.

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Mike (Salmon) Pilkenton, Chief Slab Designer
Ohio Model Planes, Team OMP Captain

(in reply to southern_touch9)
       Post #: 5

RE: Help with my new Katana 46 - 6/1/2007 4:20:50 AM   
gipper6


 

Posts: 42
Joined: 8/19/2005
From: DFW, TX, USA
Status: offline 		It's not the thrust line - I rechecked. I moved the cg farther back and it seemed to help a little, but I get the usual porposing from the aft cg. Any other suggestions.

Could the stab be incorrect? The kit had a poor stab slot - the gap was way too wide.

(in reply to AFSalmon)
       Post #: 6

RE: Help with my new Katana 46 - 6/1/2007 6:47:46 PM   
Berwyn Bill



Posts: 188
Joined: 7/19/2004
From: Berwyn, IL, USA
Status: offline
quote:

ORIGINAL: gipper6

It's not the thrust line - I rechecked. I moved the cg farther back and it seemed to help a little, but I get the usual porposing from the aft cg. Any other suggestions.

Could the stab be incorrect? The kit had a poor stab slot - the gap was way too wide.


Could be. Run a yardstick along the chord of the wing at the tip and then eyeball the incidence of the horizontal stab to see if it matches. Also god to check the thrust line this way too.

My favorite way to check the CG on a 3D bird is to get it up in the air and then roll it onto its back at about 1/2 throttle or so. If the plane wants to dive (needs lots of down elevator to stay level) it's nose heavy. I like my planes to need just a hint of down elevator to mantain level inverted flight. If it wants to climb inverted, it's tail heavy. Land and adjust then fly again.



< Message edited by Berwyn Bill -- 6/1/2007 6:50:42 PM >

(in reply to gipper6)
       Post #: 7

RE: Help with my new Katana 46 - 6/1/2007 11:33:30 PM   
AFSalmon



Posts: 3822
Joined: 5/24/2002
From: Beavercreek, OH,
Status: offline 		Thanks Bill and that's exactly how I check cg. Trim upright and then roll invereted to see where the nose goes. If the stab is off then you would have a permanent trim problem that would be solved with elevator trim. For the plane to change trim with engine thrust, your thrust line has to be off. Can you loosen your engine bolts and tilt the front of the engine more down slightly? At least try this and see how it helps.


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Mike (Salmon) Pilkenton, Chief Slab Designer
Ohio Model Planes, Team OMP Captain

(in reply to Berwyn Bill)
       Post #: 8

RE: Help with my new Katana 46 - 7/2/2007 7:02:09 PM   
renglishjr


 

Posts: 2
Joined: 2/12/2007
From: Omaha, NE, USA
Status: offline 		Did you ever get this issue worked out? I have the same problem with mine, though possibly a bit more pronounced. With the nose level, my Katana 46 will not slow down at all without the nose dropping like a brick (though it will harrier nicely). When carrying a bit of forward speed the plane flys beautifully upright and inverted, but slowing it down produces a pronounced drop of the nose - so much so that it can be almost impossible to get it back to the field in a dead stick situation. I moved my CG a half an inch aft of the suggested 5 1/4" and added down thrust to the motor and saw no improvement.

As a side note, I just put together the same ARF (though I believe a little older kit) for another member of our club and found that his flew flawlessly. Landings were an absolute pleasure with no tendancy to drop as I was able to bring the plane to almost a standstill with the nose fairly level pointing into a light wind. I was thinking that maybe a heavier motor could cause this kind of change, but upon investigation found that my motor weighed almost 1 OZ less than his.

Any suggestions?

(in reply to AFSalmon)
       Post #: 9

RE: Help with my new Katana 46 - 7/3/2007 9:21:25 PM   
AFSalmon



Posts: 3822
Joined: 5/24/2002
From: Beavercreek, OH,
Status: offline 		Well basic aerodynamics says either balance is off or you are simply stalling. Make sure you are trimmed as described previously. Trim at level flight and then roll inverted to see where the nose goes. It should remain level or drop just slightly. If all else is fine you are probably getting too slow with a high AOA and simply stalling. Go back to the basics of landing normally versus a high alpha landing. Sometimes we all get into bad habits of doing harrier landings but forgetting to keep extra power in there. You may inadvertently be thinking you are landig normally but be holding back elevator thus a high alpha AOA and stalling.

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Mike (Salmon) Pilkenton, Chief Slab Designer
Ohio Model Planes, Team OMP Captain

(in reply to renglishjr)
       Post #: 10

RE: Help with my new Katana 46 - 7/4/2007 5:16:01 PM   
gipper6


 

Posts: 42
Joined: 8/19/2005
From: DFW, TX, USA
Status: offline 		Never got the issue resolved. I changed thrust lines, cg and engines to no avail. I think the stab line is off and could be a construction flaw on some of the planes from the factory. I'm not giving up on OMP, I just think I got one that fell through the cracks. I'm open to any suggestions but I have not been able to resolve the issue.

(in reply to AFSalmon)
       Post #: 11

RE: Help with my new Katana 46 - 7/5/2007 7:45:44 PM   
AFSalmon



Posts: 3822
Joined: 5/24/2002
From: Beavercreek, OH,
Status: offline 		You guys have me puzzled. Since these are mass produced via laser parts I doubt there is any serious differences in stab alignment. Honestly it sounds like a classic stall to me.

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Mike (Salmon) Pilkenton, Chief Slab Designer
Ohio Model Planes, Team OMP Captain

(in reply to gipper6)
       Post #: 12

RE: Help with my new Katana 46 - 7/6/2007 1:44:34 AM   
gipper6


 

Posts: 42
Joined: 8/19/2005
From: DFW, TX, USA
Status: offline 		So how do I resolve a problem that doesn't exist on my other profiles?

< Message edited by gipper6 -- 7/6/2007 1:45:29 AM >

(in reply to AFSalmon)
       Post #: 13

RE: Help with my new Katana 46 - 7/6/2007 6:08:07 AM   
XJet


 

Posts: 3619
Joined: 3/31/2003
From: Tokoroa, NEW ZEALAND
Status: offline
quote:

ORIGINAL: gipper6

I can fly it at slow speeds also, but when it's time to land I either add power or nose dive. Is that normal with profiles?


Look at the thick wing section -- that's a lot of drag.

When you button off the throttle the drag slows the plane down real quick so the nose drops, it's normal behavior.

Just learn to use the elevator and remember that when you're landing: throttle controls your altitude, elevator controls your speed.

Good landings require more than just cutting the engine to idle and pointing the plane at the runway. Throttle control is what makes or breaks a landing.


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When I'm not here, I'm at RCModelReviews

(in reply to gipper6)
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RE: Help with my new Katana 46 - 7/6/2007 6:45:31 AM   
RaceCity



Posts: 1842