Some helpful websites...

Having trouble understanding a concept?  Khan Academy does a really good job of explaining almost anything math-related.

https://www.khanacademy.org/math

This site has a lot of useful information about algebra.

http://www.algebrahelp.com

Lots of stuff about engineering.

http://www.engineering.com

 
Information on aircraft design.

http://ostrevolution.blogspot.ca/p/aircraft-design.html

 

 

If you come across a website that isn't listed here, let me know and I'll add it.