What your asking for is a Flight Simulator that is: Free, under 70MB and doesnt require installation.
The answer is: If you are looking for a Flight Simualtor with those qualities then you will get what you pay for (FREE isnt always better)
If you are going to get a Flight Simulator you want GREAT quality the LEAST. You dont want to be using a FREE program that gives you horrible views.
Well I bought 5 different Flight Simulator games (Yes im a Fanatic) in 3 months. and out of all 5 games I think the BEST Bargain and Quality has to go to Pro Flight hands down.
For more info on Pro Flight or to get the game check out the Review Site:http://flightsimulatorextreme.blogspot.com