Black Hawk Helicopters <br>
<br>


<a href="http://science.howstuffworks.com/black-hawk.htm">
How Black Hawk Helicopters Work</a>

<br>
<br>

<a href="http://www.youtube.com/watch?v=vsQ0tMoNBrg">
Black Hawk Helicopter 
</a>
<br>
<br>