I saw this project listed in the PBL STARTER KIT.

But the URL listed in the book (and the clickable link in the BIE project search) do not work.

I am not sure if their website just having a bad day or under maintenance.

Does anyone have this project that I could see it (e.g. in a PDF file)?

*************

Projectile Motion
High Tech High

Students design and construct a repeatable and quantifiable demonstration of projectile motion using low cost materials.  They also need to collect and analyze data in order to determine how the motion of their projectile depends of factors such as angle of elevation and initial velocity.

http://www.hightechhigh.org/projects/?name=Projectile Motion&uid=9791ee9af1e3574d950ce9dbada4c74e

The Project Search simply redirects to external websites, so (like you said) they could have been doing maintenance.
The High Tech High link appears to be working now.  I just tried it.

http://www.hightechhigh.org/projects/?name=ProjectileMotion&uid=9791ee9af1e3574d950ce9dbada4c74e