Horizontal Stabilizer in flight

[Yerich109]

Hey Guys,

New Mooney owner, lovin' it!  Great efficiency, comfort, speed, etc....  Quick question:

 

Given the relatively low drag of the design, I was a little surprised to look behind me last week (I know, probably the only Mooney driver looking backwards) and see that the elevator was not in allignment with the horizontal stabilizer.  Since the trim moves the entire empanage, and the elevator is spring loaded to center, I would have thought during any trimmed mode of flight, they would have been in alignment (especially at cruise).  BTW:  not that I think loading would necessarily affect it with this design, but I was flying single pilot with full fuel.

 

I've seen this plenty of times in conventional tailed (trim operates tab which moves elevator) aircraft when tail heavy, just didn't expect to see it with the Mooney.  Seems like it would be adding a little un-necessary drag.  Certainly being tail heavy (not that I was) reduces wing loading, less lift needed, less drag induced, fly faster...  all that stuff...  just can't figure out in my head why they don't stay aligned.

 

Thoughts/comments?

 

 

Eric H.

N3524N

1967 M20F

Central Mississippi

[N201MKTurbo]

Adjusting the spring bungees in the tail will change that. It doesn't make much speed difference.

 

You can find the optimal position by mis trimming the plane and leveling it with the elevator and noting if the speed increases or decreases. The fastest setting should be with the plane in trim. It is usually not the position with the elevator in trail.

[jetdriven]

Covered here:

http://mooneyspace.com/topic/5404-tailplane-and-elevator-in-line-in-flight/

[FloridaMan]

I was under the (possibly mistaken) impression that it's a CG thing. 

 

And if Al Mooney was really trying to reduce drag, why didn't he opt for the ruddervator like the Bonanzas of the time?  (I kid, I kid)

[M016576]

I was under the (possibly mistaken) impression that it's a CG thing. 

 

And if Al Mooney was really trying to reduce drag, why didn't he opt for the ruddervator like the Bonanzas of the time?  (I kid, I kid)

I guess Al actually liked Doctors, didn't want to kill them all ;-)

[sreid]

The elevator position varies with the position of the moon, and is always aligned with the stab at high tide. You will notice a higher TAS at high tide. This is why the Garmin 496 has a celestial tab, with sun/moon and tide sub-tabs.

[Yerich109]

Perfect. Thanks guys.

-Eric

[Alan Fox]

Correct me if I am wrong , but since the horizontal stab is almost flat , doesnt it need a little deflection to create lift and (fly) , as if it is flat , it is basically a weathervane.....

[Hank]

Only if it has zero angle of incidence. In other words, practically never.

[jetdriven]

Correct me if I am wrong , but since the horizontal stab is almost flat , doesnt it need a little deflection to create lift and (fly) , as if it is flat , it is basically a weathervane.....

Except the angle of deflection is backwards for that. The tail should provide downforce in cruise, but the elevator is deflected down.  I have no explanation for it, except perhaps the horizontal stabilizer has a negative incidence and the elevator trails behind it.

[Alan Fox]

Except the angle of deflection is backwards for that. The tail should provide downforce in cruise, but the elevator is deflected down.  I have no explanation for it, except perhaps the horizontal stabilizer has a negative incidence and the elevator trails behind it.

Depending on CG , the tail can "fly" with upward or downward force...

[jetdriven]

Only on a V-tail !

[Super Dave]

Depending on CG , the tail can "fly" with upward or downward force...

Unless it has canards or digital fly-by-wire, the tail will be producing downforce on any airplane within CG limits.

[Super Dave]

perhaps the horizontal stabilizer has a negative incidence and the elevator trails behind it.

I think that's exactly what's going on.

[carusoam]

Alan was flying inverted in the v tail...

Best regards,

-a-