amyvega2005(at)earthlink.
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 Posted: Thu Jul 31, 2008 8:05 am Post subject: 1 Last Post-open to critizism both constructive & otherw |
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I would just ask AMD if they changed the angle of incidence to the horizontal stab, the engine mount as well as the wing? If they changed the stab and wing, the speed would not vary significantly. Engine mount would be insignificant at torque and speeds we fly,You could probably change the angle enough with a few well placed washers. You could do all three to the 601.
I disagree with the thought the "Bad name" of the 601 would go away. What bad name? Some guys flew it out of spec so blame it on the plane?
Interesting how we always blame the machines not the men.
Juan
| Quote: | From: Paul Mulwitz <psm(at)att.net>
Sent: Jul 31, 2008 11:22 AM
To: zenith-list(at)matronics.com
Subject: Re: 1 Last Post-open to critizism both constructive & otherw
Hi Sabrina,
I agree with your analysis and conclusions.
By lowering the trailing edge ZAC has not only increased the
decalage, they have also changed the wing incidence angle as compared
to the fuselage. I think both approaches (yours and theirs) add a
bit to the pitch stability compared to the original design.
From the comments posted by others, I think ZAC's goal was not to
increase the stability but rather to increase the forward
visibility. By changing the incidence they have made a bigger impact
on the airspeed capability of the plane. The fuselage (or wing,
depending on how you hold your head) has more parasitic drag because
of the incidence change.
In short, I think you have traded stability for drag while they have
traded forward visibility and stability for even more drag.
I don't know what happens if they align the engine thrust with the
longerons rather than the wing. I guess throttle changes will have
more impact on elevator trim. I have no opinion on your pre-loading
point with regard to the spar angle.
However, I still think (as I posted a few days ago) they are hoping
the bad publicity associated with the XL will all go away because
they changed the model name.
Paul
XL getting close
At 07:29 AM 7/31/2008, you wrote:
>The decalage change still bothers me...
>
>I increased the decalage, be it aerodynamic or geometric, by
>pitching my horizontal stabilizer down two degrees.
>
>Zenith has now increased the decalage by lowering the rear of the
>wing and maintaining the status quo on the horizontal stabilizer. I
>am told, second hand, this is done without ANY change to the main
>spar set angle (that is why I wanted to compare plans.)
>
>Both the 650 and Sabrina are inherently more stable than the 601
>with this increased decalage giving it the ability to dampen larger
>vibrations/oscillations. We both loose performance. The 601 is
>more efficient. Correct?
>
>With a factory O-200A engine mount, the engine mount aligns the
>center of trust with the main longerons.
>
>Does the twisting of the 650 main spar (if indeed it remains as
>speced in the 601 plans) add strength to the structure by pre-loading it?
>
>I lowered the leading edge of the my horizontal stabilizer to better
>balance the airplane so will it fly level without trim (heavy
>engine) compared to the line of thrust and main longerons. The
>added benefit was additional stability.
>
>By lowering the rear spar, the aircraft will fly more nose
>down. To fly level, the 650, with a 601 engine mount, no longer
>flies along its line of thrust or main longerons. Correct?
>
>Comments?
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