Is thrust to weight ratio based on weight of the copter alone or including payload as well?
For example, say I have copter which ways 1000g and carrying a 200g camera. If i want a 2:1 thrust to weight ratio, should I design it so that the thrust is 2400g or 2000g? Is there an official method for which this value relates to?
1200g of thrust at 50% throttle minimum. Because thrust is not linear with throttle (there is Expo involved) you would aim for higher than that. Buy a subscription to eCalc and run some scenarios. If the result is 50% linear mid-throttle or less it will work.
Note: You may read some criticism of eCalc as not being accurate. They most likely don’t know how to use it (GIGO). I have been using it for years with I don’t remember how many builds and it has always been very close to actual. So much so that I buy the battery last based on it’s weight to meet the desired thrust/weight.