According to official FAA documentation, the first stage of Falcon 9 v1.1 is capable of holding 119,100 Kilograms of Rocket Propellant 1 and 276,600kg of Liquid Oxygen. The empty mass of the first stage is not known, but can be estimated at around 23 to 26 metric tons, depending on the version used (earlier estimates ranged from 18 to 25 metric tons).
Let’s do the math(s) for the return flight
For simplicity we may leave out the Potential Energy (PE) that is needed to gain altitude and which is recoverable on descent.
This is negligible compared to the kinetic energy (KE) involved
At the point of separation the velocity is 5,600 Km/h
Let’s first use the handy calculator
Rocket Equation Calculator http://bit.ly/2aLwPOG
to check on the launch parameters. (approximate numbers)
Full mass = 500,000 Kg
Dry mass = 100,000 Kg
Specific impulse = 282 (published figures)
Delta – V = 4,500 ( Km/h?)
That’s near enough for rocket science.
Now for the return trip.
Full Mass = X
Dry mass = 25,000 Kg
Specific impulse = 282
Delta-V = 6500 Km/h
( assuming 2000 Km/h supersonic return velocity)
Calculate to find Full Mass…..click
Full Mass = 200,000 GOLLY!!
You need 200 Tons of fuel to make the rocket stop and fly backwards at supersonic speed.
And then you need rather a lot more to slow it down and land.
Elon’s not using rocket science.
He’s using VOODOO Science.
Where are the videos from TV stations covering the landing?
I can only find videos from Elon’s gasping followers that show a bright light in the sky.