The Aviation Herald has a very good writeup: <a href="http:&#x2F;&#x2F;avherald.com&#x2F;h?article=47770f9d&#x2F;010&amp;opt=0" rel="nofollow">http:&#x2F;&#x2F;avherald.com&#x2F;h?article=47770f9d&#x2F;010&amp;opt=0</a>