Hello everyone  I've a question,

 

For example I'm flying with headwind 70-80 knots. This will cause engines to run faster and so I will have fuel problems. How can I calculate how much extra fuel do I need for strong headwinds (e.g. 70-100 kts )

It wont cause the engines to run any faster. They will run as normal and your cruise KIAS or Mach number will be the same as in still air.

 

What will be different is the chunk of air you are flying in is being moved away from your destination at say 70 nm per hour. Thus your groundspeed, lets say 450 knots in still air, will now be 380 knots.

Assume the cruise section of the flight is 450 nm and this is where you encounter the headwind. in still air you would cover that in 1 hour at 450 knots groundspeed. At 380 knots groundspeed it will take you 1.18 times as long , so 1 hour and 11 minutes. You will need to know how much fuel your aircraft burns per hour, do the calculation for 11 minutes extra and add that on.