Hi,

I am a newbie here and I have a few small question regarding the IMU theory.. 

First question is that for example if we are using 3 helicopter tail gyros in 3 axis of an aircraft why cant we successfully stabilze the aircraft ?

According to the paper http://144.206.159.178/FT/CONF/16421939/16422032.pdf

A gimbaled vertical gyroscope is able to meet the requirements for
attitude measurements. But the volume and power consumption of vertical gyroscope is so large that it can not meet the requirement of small UAV.

And according to the 

gentlenav.googlecode.com/files/DCMDraft2.pdf

Mixing. It was recognized that in a banked turn, there were two
problems arising from the bank angle. First, the yaw rotation of the
aircraft around the turn generated a nuisance signal in the pitch gyro,
because of the banking. Second, in order to make a level turn, the
elevator needed some “up” deflection. The amount of deflection
depends on the bank angle, which could not be directly measured.
Both issues were opposite sides of the same coin.
• Acceleration. An accelerometer measures gravity minus
acceleration. The acceleration is equal to the total of all of the
aerodynamic forces (lift, thrust, drag, etc.) on the plane, plus the
gravity force, divided by the mass. Therefore, the accelerometer
measures the negative of the total of all of the aerodynamic forces.
The measurement of gravity is what is needed to level the plane but
that is not what you get out of an accelerometer during accelerated
motion. Acceleration is a confounding variable. In particular, when
the aircraft pitches up or down, for a short while it accelerates in
such a way that the output of an accelerometer does not change.

Can you please explain this thing a little bit. 

I tried so hard to find this thing in the internet but ended up bad.

I appreciate it verymuch and thanks a lot for your time and cooparation..

BR

Kanishka