Newton's "Floating" Apple ?

This is about reducing the cost of weightlessness or Zero G to 1/100, that is, $5,000/ride to less than $50/ride so that everybody can afford it.  
Newton’s falling apple is the best known story in science, so famous that it eclipsed another equally significant work in the history of science, that is, Newton’s cannon ball. His imaginary experiment of firing cannon balls on top of a mountain provided the basis of modern space exploration. By ignoring the air drag, Newton imagined that if enough horizontal speed was given to a cannon ball, it would fall along the curvature of the Earth and never hit the Earth’s surface. His cannon ball in orbit is an artificial satellite similar to the Moon that falls along an Earth’s orbit forever. Newton’s apple will fall down to the Earth because it has no horizontal speed. Since everything inside a spacecraft in orbit falls together, the crew members onboard experience weightlessness as we have seen on NASA videos. If an astronaut stands on a scale it would read 0. An observer far away would realize that the reason for this phenomenon is because the astronaut and the scale are both following each other in a free fall path along the orbit.

Figure 1: Newton's cannon ball is the basis for modern Space exploration!

In science, Newton’s cannon ball is as important as his apple. Cannon balls A and B are falling back to earth like Newton’s apple because they do not have enough horizontal speed to fall along the curvature of the Earth. One of these cannon balls will finally be fast enough to fall forever along with the Earth’s surface and achieve a circular orbit, as ball C does in the diagram. This perpetual free fall may have caused many people to consider that only free fall creates weightlessness. 

Let us start a fresh approach to zero gravity and free fall. Encyclopedia Britannica and Wikipedia’s definitions of weightlessness are similar. Weightlessness, the condition experienced while in free-fall” (Encyclopedia Britannica). Weightlessness or zero gravity is “the condition that exists for an object or person when they experience little or no acceleration away from the acceleration that defines an inertial trajectory, or the trajectory of pure free-fall” (Wikipedia as of May 2012). Unfortunately, these definitions are incomplete and misleading. “Weightlessness = Free fall only” is a very common perception. This is why most people, even those well-educated in science, have the misconception that weightlessness can be created only during free fall. As a matter of fact, weightlessness can also be achieved while objects are going up within Earth’s gravitational pull by an upward momentum. We shall explain it in a moment. Let us check the following diagram. 

Figure 2: Something is not right in this diagram

The above illustration is supposed to explain how weightlessness works in today’s Zero G flights. It is misleading and associates weightlessness or zero G to free fall only. Can you tell what went wrong?

Please examine the powerful parabola portion at the upper left. The drop starts at 30 seconds and continues to 1 minute, a temporary zero gravity is achieved on the descent. It is very easy to mislead the readers into thinking that only the free fall part of the parabolic flight creates Zero G or weightlessness.

Believe it or not, the diagram is flawed. If a Boeing 727 was to be maneuvered like that, it would be a Kamikaze Divine Wind (神風) mission. The dive speed would be supersonic. It could not be recovered from a condition like that without damaging the structure of the aircraft. However, it is safe and true that more than 25 seconds of weightlessness can be achieved each cycle on this flight for paying thrill-seekers. The correct diagram should look like the following. 

Figure 3: This is the corrected illustration

What really happens is that the pilots engage a full throttle, accelerate the aircraft and pull up to the injection point as indicated in the diagram. There is a high G before the injection point. With a large upward speed accumulated, the pilots then reduce the throttle to minimum at the injection point. This is to overcome the air drag and keep the jet on a free ascending parabolic flight path, flying over the top and diving along the parabolic path to the recovery point. The cabin and everything inside experience Zero G during this time period. During the free ascent, everything inside is slowing down at the same rate. At least half of the weightlessness duration is achieved while the aircraft is still climbing by its inertia. During the free fall dive, everything inside is accelerating at the same rate. The free falling part contributes the other half of Zero G duration. An observer from far away would realize that the reason is that the aircraft, the passengers and everything inside are all following each other in a free ascending, and then free falling parabolic path. There is no contact force acting between everything inside the cabin. If a passenger stands on a scale it would read 0. Zero G is achieved on a powerful parabola, not just the falling part. 

Starting from the recovery point, the pilots pull up the aircraft to start a level flight at 24,000 ft and begin the next cycle. According to the company information, this kind of delicate maneuvering can not be done with an advanced onboard auto-pilot. The quality of the weightlessness is also up to the skill of the pilots, weather and other factors. The operation is expensive. The Zero G cost using this more than half century old technology is understandably very expensive. It was calculated that only one person out of a few hundred thousands in the population had the chance of experiencing this zero gravity. A completely different approach to achieve the same effect cheaply will be discovered as follows.  

We shall learn from Newton’s method of conducting conceptual or imaginary experiments to reach a different workable Zero G machine. The realization of this new Zero G machine will provide us with much cheaper and better weightlessness in the future. An analogy to the Zero G flight path is a mortar shell trajectory. The shell accelerates from the bottom of the barrel to the muzzle. The muzzle is equivalent to the injection point as seen in Figure 3 because the shell will be in a free ascending state after passing the muzzle. Once the shell leaves the mortar barrel, there is no external force applied to it. Everything is slowing down at the same rate, so weightlessness is experienced inside the shell as in a Zero G flight. Again, by ignoring the air drag like Newton did, the trajectory is also a parabola as the Zero G flight path. 

Figure 4: Modern mortar shells are used here instead of Newton’s old cannon balls. A mortar is different from the cannon for it is shooting with a high angle of elevation. An ant inside an empty shell will experience zero G during the free ascent and descent just as the passengers in a Zero G flight.

Next, imagine that we are firing the mortar with higher and higher elevation angles until it is shooting vertically up. It makes no difference for the ant inside the shell whether firing at 90 degrees up or any other angles. Zero G is inside the shell once it passes the muzzle (injection point) the shell is in a free ascent and then free fall. The horizontal speed is not changing and is irrelevant. There is no horizontal acceleration because the gravity is always downward. The horizontal motion is not felt by the passenger inside the Zero G flights either.

We are sure now free ascent and free fall have the same effects of achieving Zero G or weightlessness. This vertical method of making Zero G could have doubled the weightlessness time for the drop towers in our amusement parks today. The drop towers are not taking advantage of this upward free ascent because the technologies were not there yet. It requires a catapult to shoot thrill-seekers up safely. Shooting payloads up using explosive like mortars is not practical.

The various technologies required for a land-based vertical Zero G machine are already available. U.S. Navy and few defense contractors have developed and tested an Electro Magnetic Aircraft Launch System (EMALS) to replace the old steam powered catapults for navy carriers. The same technology has already widely used in amusement parks to drive roller coaster carts, like this zero G roller coaster in Six Flag Magic Mountain, Southern California.

   Figure 5: A zero G roller coaster for 6 seconds of weightlessness


Height is another requirement for the Zero G machine. A tall vertical structure is needed. A tall building of 200-meter (about 600 ft) above a 100-meter (300 ft) deep shaft structure for a total height of 300 meters (900 ft) can produce up to 12 seconds of 0G/weightlessness each cycle, similar to the zero G flights.


    Figure 6: A vertical zero G ride located in a downtown area

It is worth noting that if the zero G duration is to be reduced somewhat, the costs and height would be reduced exponentially because of the physics of linear constant acceleration. The terms of injection and recovery points are used in the Zero G flight industry. They are also very important points in designing the vertical Zero G facility. A high acceleration electromagnetic catapult is needed below the injection point to accelerate the Zero G vehicle up. The free ascending and descending sections need only a low acceleration linear motor similar to the propulsion of magnetic levitation (Maglev) trains. Ideally, there is no need for any propulsion during the free ascent and free fall periods. Low power propulsion is after all necessary just to overcome the air drags and other friction forces that Newton and we had ignored in the conceptual experiments. The electromagnetic catapult turns into a generator when the zero G vehicle falls below the recovery point to slow down and generates electricity like a hybrid car during braking. 

The readers may have noticed in Figure 2 that the lunar and Martian gravities can be performed with the Zero G flights. The vertical Zero G machine can also simulate better lunar and Martian gravities with the computer control automatically. This is a good arrangement for the riders to reduce motion sickness. During the high G period between the recovery point and next injection point, human muscles and bone structures need to adjust to the increase of forces applied to the body. This gradual ramp-up to high G's is smooth and exhilarating. Studies showed that this “G-forced” exercise is an excellent way of preventing and reducing obesity. This land based electromagnetically driven Zero G facility can be operated 24/7. All kinds of business operation models become possible with this new technology. For example, the Zero G facility can be a weightlessness attraction during the day and Zero G honeymoon suites during the after hours in order to maximize revenue. It is estimated the ticket cost of weightlessness can be reduced to 1/100 of today’s Zero G flights, that is, $50/ride vs. $5,000/ride.  

Zero G is different from the sport of indoor skydiving/vertical wind tunnel or ifly. During a skydiving your weight is supported by the strong wind and divers need heavy protective gears and goggles. Riders of the Zero G experience no weight at all like the astronauts in space, and can be dressed as usual. 

Newton had envisioned Zero G three hundred years ago. NASA had done that with a propeller passenger aircraft more than fifty years ago and few companies are running their businesses with commercial jets for the very few. It is time to make zero G available to everybody. If the Zero G tourist attraction can be realized in a U.S. city, it will draw visitors from around the world and boost local economy. The investment and operating costs is much less than today’s zero G flights. The business is very complementary to the commercial space travel industry that Virgin Galactic and SpaceX are pioneering. Inter-disciplinary cooperation and public support is critical to bring this Space Experience Economy (SEE as Space Tourism Society called) to consumers. It is a peaceful application of a defense technology. Your suggestions and ideas will be greatly appreciated!