Yes, I agree all is very easy - to slow down a heavy (43 000 kg) space ship in space from one high speed to another, little lower high speed, you apply a substantial force on it (eg 97 400 N), e.g. by using a 1960's rocket engine. The rocket engine consumes fuel in order to slow down the space ship. What is the fuel consumption (kg/s) to produce a certain force (N). According my calculations one kg fuel can produce 1.63 MJ energy to produce the required force.
This is where you err. And where you will never be able to achieve the right answers.
Let's put it as a thought problem. Say I have a little wind-up toy car. With the spring fully wound, that spring stores enough energy to drive the car forward about 8 meters on a smooth, level floor.
I take my little wind-up car with me on a flight from New York to Paris. After the airplane has reached cruising altitude and level flight I set my little wind-up toy down in the center aisle.
Does it travel the same distance it did back in my room at home? Does it travel further if I turn it around so it is rolling from the front of the airplane to the back?
The equations you are using claim that, yes, not only will the range of my little wind-up toy car be affected by the fact that I am using it in an airplane in flight, it will be GROSSLY affected; enough so that I would be lucky for it to roll at all.
It is not very efficient = more fuel is needed than can be carried, it seems.
Applied to a seagoing ship means that the ship sinks prior departure. Not very nice.
Imagine a 43 tons car on your door step. Imagine the engine you need to accelerate this heavy car to 2 400 m/s speed. It will be quite big. And now you want to brake from 2 400 to 1 500 m/s speed using a brake. You agree it is a big brake.
Or take the Shuttle - about 78 tons - flying at 7 800 m/s speed around the Earth at 400 000 m altitude to/from the ISS. To slow down for going back to Earth, the Shuttle is turned around and the engines are on full blast but the only result is that the altitude becomes lower and the speed increases to 9 000 m/s at 150 000 m altitude ... while you are still going backwards. You are flying backwards! How to stop?
No. After one burn, regardless of which way the Orbiter is facing, it will NOT be in a circular orbit that is higher or lower in altitude. It will not be in a circular orbit, period.
I'd suggest at this point getting a copy of Lunar Orbiter or similar and playing around until you get an actual feel for orbital mechanics. Because your attempts to model it mathematically are leading you astray.
It is not possible. Not even a computer can land the Shuttle. But Captain Mark Kelly managed to do it. I explain how in my presentation. Enjoy.