I am trying to build a rocket. How much lift do I need to clear earth's gravitational pull?

Question

Let's assume the rocket carries four passengers and their belongings for a two-year tour.... and the rocket weighs roughly 18.631 tons. that includes fuel load. my tests thus far have proved disastrous. it's possible only three passengers will be well enough to make the trip.

Answer 1

This is a question of simple double differential calculus as applied to the Eigenvector of force formulation within a quadratic equation. Assuming a fuel with a specific impulse of 100, 000 giga newtons per cm3 then of your 18.63 tons of payload approximately .01grams of that would need to be fuel. The rest would have to made up of passengers and cargo which only account for aprox 1 ton and the rocket structure say 2 tons leaving 15.5 tons of ballast to prevent your rocket overshooting and escaping the gravitational pull of the Solar system. Don't forget to pack clean underwear, lots of it.

Answer 2

Your project is ambitious even for the wealthiest nation on earth. The Apollo Project of the late 1960's and early 1970's put three men into a trans lunar orbit and the mission lasted less than two weeks. The Saturn V rocket was required to escape the gravity of Earth with sufficient additional energy to allow the capsule to coast to the moon.

You will need to generate sufficient force to accelerate your rocket from 0 to 11.2 kilometers per second without crushing your passengers. The numbers are huge. If you phrase your query just right, I'm sure there is a web site that could give you the answer.

Answer 3

You simply need thrust that is higher than the force of gravity, i.e. the weight of everything carried, the rocket and the fuel itslef (you have to lift the fuel along with you).
But then, how much more thrust you have above the weight makes the difference between hovering there and wasting all the fuel going nowhere and actually picking up speed on the way to orbit.
The Atlas missile that was used to put the first American astronauts in orbit in the early 1960's, weighted over 127 tons--most of it being fuel-- and that was with only one person capacity.
And only in orbit, for a trip that lasted less than one week.
Your 18 tons are waaay too low, unless you'd have access to nuclear power.

Answer 4

Lift is not what you're looking for, it's "delta v"...how much the rocket can change it's velocity. It starts on the pad, going 0 mph, and goes...somewhere, most likely at a speed of at least 18,000 mph. So, you need a delta v of 18,000 mph, at the very least, just to make earth orbit.

"Lift" would usually be thought of as "thrust", or how hard the engines push against the structure of the rocket. Launching from earth with a rocket that weighs 18.631 tons, at a minimum, you need 18.631 tons of thrust. Unfortunately, that would only make it hover above the pad, not go anywhere. Large rockets intended for space travel have a thrust anywhere from 1.25 times their weight (the Saturn V moon rocket) to 1.5 times their weight (the Space Shuttle). For your rocket, that would be 23.289 tons to 27.947 tons of thrust.

As the rocket burns off fuel, it weighs less and less. Unless the rockets "throttle down" to produce less thrust, the acceleration will rise and rise. So long as it doesn't get too high for your passengers or cargo, that's a good thing! For example, the Shuttle starts off at 1.5 times it's own gravity at the pad, but by the time it reaches orbit, they have to throttle down the engines to keep the thrust below 3 times the weight of the vehicle (it burns that much fuel)!

Good luck with your rocket.

Answer 5

How can you know how much your fuel load is going to weigh if you do not even know how much lift you are going to need to make orbit?

Answer 6

damn man, i wish if i could help
pray for some one like NEWTON is alive so that he could help!!!
wish u all the best....