# Aircraft Simulation for beginners

1. Apr 17, 2010

### eaglestrike

Hello everyone
For the past 2 years I have slowly and agonisingly tried to make a flight simulator in http://www.blender.org" [Broken]. I've gotten as far as this (regarding physics):
- got the Lift and Drag calculations
- got the thrust calculations
- got some REALLY basic roll calculations.
It is the the steering physics and flight dynamics I need help with now. I read that ailerons cause roll by deflecting air in certain directions. This causes the net lift to change and makes the aircraft rotate around its longitudinal axis. So I've come up with a whole lot of calculations that calculate the lift on different parts of the wing and calculate the difference in lift, and then use that to create torque. This works. But as I know, this isn't the only variable in aircraft roll... I know inertia is another one, but not much else (http://en.wikipedia.org/wiki/Flight_dynamics). What I need is some very simple but applicable roll calculations that can be used. I'm assuming at the moment that the same calculations can be adapted to work for the elevators and rudder. And as a note I would like to say that I am an eleventh grader with some common sense (hopefully!).
My current resources are:
http://www.auf.asn.au/groundschool/umodule4.html [Broken]
http://www.av8n.com/how/#contents

Thanks.

Last edited by a moderator: May 4, 2017
2. Apr 17, 2010

### fedaykin

Sorry to be of relatively little help, but here is a suggestion. You'll need the mass of the object and its moment of inertia. Moment of inertia, I, can be approximated by $$I = sum(m_i * r_i ^2, i, 1, N)$$ .

This only applies to rigid bodies, and even then, it's an approximation if the shape of the object is complex enough.

I is analogous to mass as rotational kinematics is to linear kinematics. Perhaps it would be accurate enough to approximate I with the sum written above. Chop the plane up into areas of known mass and center of mass. Then calculate the distance to the center of mass of the plane.

3. Apr 18, 2010

### eaglestrike

I was going to add that. Can you please explain the equation (as what mi is) ... also, will I have to integrate the different centres of the aircraft? as will the centre of lift have to be different altogether than the centre of gravity, or can I balance it with trig??

4. May 3, 2010

### fedaykin

$$m_i$$

The subscript i is for index. That means you sum up the each section's mass times distance from the plane's center of mass squared for as many sections of the plane as you want. You then repeat this for each section and add together all the results. You must do the whole plane though, and taking a very small number of sections can be quite inaccurate.