stunthanger.com
Design => Engineering board => Topic started by: Tim Wescott on June 30, 2016, 02:25:25 PM
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Just sitting here in uffish thought, wondering:
One of the cited advantages for a large tail in a stunter is because it makes setting the CG less critical, and the flight characteristics thus do not change as much over the course of the flight. But in an electric plane, which carries its spent fuel with it throughout the flight, the CG does not change.
So, if you're designing specifically for electric, would you contemplate making the tail smaller?
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Just sitting here in uffish thought, wondering:
One of the cited advantages for a large tail in a stunter is because it makes setting the CG less critical, and the flight characteristics thus do not change as much over the course of the flight. But in an electric plane, which carries its spent fuel with it throughout the flight, the CG does not change.
So, if you're designing specifically for electric, would you contemplate making the tail smaller?
Tim, my understanding of the larger tail is different, ( both of us may be wrong too) I was under the impression that having a larger tail allows you to carry the CG farther back on the MAC and still maintain stability. Electric airframes tend to want to be more nose heavy than IC setups, so I would think shrinking the tail would exasperate the problem and possibly cause you to push the cg farther forward
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Tim, my understanding of the larger tail is different, ( both of us may be wrong too) I was under the impression that having a larger tail allows you to carry the CG farther back on the MAC and still maintain stability. Electric airframes tend to want to be more nose heavy than IC setups, so I would think shrinking the tail would exasperate the problem and possibly cause you to push the cg farther forward
As far as I know, the larger tail increases the range and moves it back. But -- what's wrong with having a narrower, more forward range? (Note: I'm not arguing for or against this -- I'm just curious if anyone's run it through their gray matter, and what they thought of it).
When you balance your electric ship more forwardly than your gas ship with an empty tank, are you going further forward than your gas ship with a full tank?
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As far as I know, the larger tail increases the range and moves it back. But -- what's wrong with having a narrower, more forward range? (Note: I'm not arguing for or against this -- I'm just curious if anyone's run it through their gray matter, and what they thought of it).
When you balance your electric ship more forwardly than your gas ship with an empty tank, are you going further forward than your gas ship with a full tank?
as normal Tim, I am blathering too, hoping if I am whacked that Brett or Paul will pop in and correct us/me
The CG can affect the point the airplane pivots in the corners and the appearance of the corner thus affecting scoring.
and YES the happy place CG on my electric airframe is farther forward than it is with a IC GLow and full tank Happy place.
I think if you actually tested the CG shift on a glow airframe you might be surprised and how little it moves. but thats my opinion,, I know I can move my battery ( 14 ounces) and I was surprised I thought the room I had was going to make a big difference,, not as much as I thought
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A bigger tail allows you to move the CG farther aft for the same stability or farther forward for the same turning ability. My guess is that the electric Impact's tail is sized by its ability to rotate the airplane. Because the happy-place CG on an electric Impact is forward of the full-tank happy-place CG on an IC Impact, I'd guess the electric Impact's tail would need to be bigger.
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A bigger tail allows you to move the CG farther aft for the same stability or farther forward for the same turning ability. My guess is that the electric Impact's tail is sized by its ability to rotate the airplane. Because the happy-place CG on an electric Impact is forward of the full-tank happy-place CG on an IC Impact, I'd guess the electric Impact's tail would need to be bigger.
Hey I was kinda right for once,, miracles never cease
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I think the big tail makes all ships better. I have changed the tail on an electric powered Tutor II, going from the original about 18% up to 23%. The ship in level flight flew pretty much the same. In maneuvers the big tail gave better shape at the same CG location. When I started to move the CG back the big tail came alive. I was able to move the CG back to the 25 - 27% point and tightened maneuvers size almost to tight (nice to have that option) and still be stable in level flight and coming out of corners. I like setting the CG to achieve the smoothest, tightest (closer to the rule book size) maneuvers that you can get. The electric power allows moving in this direction without having to compromise for the CG shift.
Best, DennisT