Weight and balance

[Seeker]

Now and again I actually get on some one's six (strange, but true), and if I'm sucsessful at sniping their tail off at long range they invariably go nose up before fluttering to the ground.

My question is this:

As far as I know, all conventional aircraft have thier C of G forward of the MAC line; that's to say that the tail exerts an constant down moment to prevent the nose pitching down ( the centre of lift being the pivot point).


So I would expect to see a suddenly tailess plane go nose down first before doing the sycamore leaf manouver; not nose up.

Any one have a view on this?

[AKSWulfe]

In my days of building balsa wood models, I had a tail rip off a plane... it flipped nose first upward and eventually crashed into the ground.
-SW

[whels]

Originally posted by Seeker
Now and again I actually get on some one's six (strange, but true), and if I'm sucsessful at sniping their tail off at long range they invariably go nose up before fluttering to the ground.

My question is this:

As far as I know, all conventional aircraft have thier C of G forward of the MAC line; that's to say that the tail exerts an constant down moment to prevent the nose pitching down ( the centre of lift being the pivot point).


So I would expect to see a suddenly tailess plane go nose down first before doing the sycamore leaf manouver; not nose up.

Any one have a view on this?

Seeker a plane with power on tends to climb nose up without trim. tail gone = no down trim, so the engine over powers the CG
and nose goes up quickly.


whels

[Seeker]

Thanks guys.

I'm not at all saying HTC's got it wrong; because my empiracle observations match Wulfie's (I too break a lot of models ); I'm just trying to understand it out of idle curiosity.

However, Whels' point about engine thrust would mean that the thrust line whould be pointing up at a hell of an angle; which I would have thought would be very inefficient.

I've attatched a work of art to make Urchin jealous, hopefully it'll explain my confusion better!

[fats]

I've got my Fw 190 drawings somewhere, but the engine was angled up. Not by much but something like few degrees.

They are 1:8 scale and no source given. No way to tell if these are factory drawings or RC scale. They do list gunsight offsets and seating arrangements ( incline etc. ) and other non RC related so it would point to drawings of a real aeroplane?


// fats

[Joker312]

I happen to have a VHS of a Corsair knocking the tail off a Zeke.
The Zeke flips up and over very rapidly. I am not sure if this was due to the flight configuration or the aerodynamic principals involved.

[john9001]

the tail does not hold the back of the plan down  it holds the back of the plane up

[funkedup]

For a stable conventional aircraft, center of gravity is aft of the wing's center of lift.  Horizontal tail also generates lift, which moves the aircraft's center of lift aft of the center of gravity, giving the aircraft a margin of stability.  If the horizontal tail is removed or destroyed while the aircraft is in level flight, the aircraft should pitch up uncontrollably.  You can read this in any aeronautical engineering textbook.

Forgive my crude diagram:

     A.C.(wing)     A.C.(tail)
     |              | __
     |      A.C.    |/ |
     |       |      |  |
 ____|_______|_____/|__|
/   _|__  o  o      |_ |
\__/____\_|________/__\|
          |
          |
         C.G.

A.C. = Aerodynamic Center (center of lift) of the aircraft as a whole.
A.C.(wing) = Aerodynamic Center (center of lift) of the wing ONLY.
A.C.(tail) = Aerodynamic Center (center of lift) of the tail ONLY.
C.G. = Center of Gravity

[Holden McGroin]

Center of Gravity is generally in front of the Center of Lift, and in a conventional airplane, the elevator is a net down force, in a canard configuration, the front mounted elevator exerts a net lifting force

[Naudet]

As far as it relates to the FW190.

That plane had a nose down attitude in level fligh of about 5 degree.
So i think it's natural tendency would be to climb, without a counteracting force fro the tailplane resulting in that nose down level flight attitude.