Do we have a freeware take off data calculator?

There is none. I believe during beta testing when the T7 was not in TOPCAT and TOPER didn't exist the beta team used a derated takeoff of 1. You could try this if you don't want to spend any money.

There is none. I believe during beta testing when the T7 was not in TOPCAT and TOPER didn't exist the beta team used a derated takeoff of 1. You could try this if you don't want to spend any money.

 

The process was more "I have a lot of thrust, and I'm kinda heavy, so TO2 with no assumed temp should work...I hope...maybe...damn...well I'll send the virtual arborists out to plant more virtual trees next to the virtual airport."

 

...that or I'd just leave the rated thrust and just ignore the idea that you usually get an initial altitude. In fact, my first takeoff, I removed the payload, set about 10,000 pounds of fuel, left rated thrust, firewalled the throttles, and went rocketing off into the skies over DC.

There is a 777-200 derate calculator in the avsim library. In the FSX utilities section.

 

http://library.avsim.net/download.php?DLID=179410

I believe Aurasim will be producing a performance app shortly for the 777; they already have one for the Q400. You have to pay a small fee though.