The Pilot Down Force works well in a wide range of situations.

The Pilot Down Force is our favorite pressurized ink pen for the broadest range of applications. It works well in most circumstances, including writing at an angle, on wet paper, and in cold or heat. It does not write well on oiled paper. It has a wide body and a firm, slightly concave rubber grip. Despite its sturdy construction, its plastic body is quite light. We found it the most comfortable to hold of all the pressurized ink pens.

The Down Force’s large binder clip is its most noticeable feature. It attaches firmly to notebooks and includes a lanyard hole if you need to fasten it more securely. Overall, the pen has a practical yet cohesive design that is suitable for casual environments without appearing too inelegant for more professional situations.

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• Test Results
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• How We Approach Research & Testing
• A Pen That’s Out of This World
• Conclusion

Regular ballpoint pens rely on gravity to dispense ink, which is why they cannot write at certain angles. Although perfectly adequate for writing on horizontal surfaces, what happens when you're faced with a vertical or upside-down surface? To tackle the problem, pressurized ink pens were were developed. These pens compress the air inside the ink cartridge to force ink out, allowing you to write on difficult surfaces at varying angles. This is achieved in one of two ways.

The first method uses pre-compressed air in the ink cartridge to ensure that ink is continually pushed toward the tip. The ink used in these pressurized cartridges is also more viscous, preventing unwanted leaks, and only liquefies as a result of friction during writing. The second method uses a mechanism on the pen body to inject air into the cartridge, called the retraction method. The energy from each push of the pen cap forces air into the ink cartridge, creating a pressurized state which allows the ink to be pushed toward the tip.

Contrary to popular belief, NASA did not spend millions of dollars trying to perfect an anti-gravity pen while the Russians simply used pencils. In fact, NASA did have a stint with pencils, but they came with their own set of problems. Pencils were prone to breakage and the little wooden shards could cause dangerous situations as they floated around the cabin. Moreover, the wood and graphite could burn rapidly in a pure oxygen environment. After a fire in Apollo 1, where three astronauts tragically died, it was obvious that they needed a better solution.

At the same time, independent of NASA, Paul Fisher was working tirelessly on the "perfect pen"--a pen that wouldn't leak or dry up, would write underwater, and would write in extreme temperatures. After many iterations and over a million dollars of research and development, he finally presented the "Anti-Gravity" Pen to NASA in 1965. NASA tested the pen for two years before determining that the pen indeed fulfilled all the requirements that NASA had for a writing instrument. It would work:

• In a vacuum.
• In zero gravity.
• In hot temperatures.
• In cold temperatures.
• Without burning in a pure oxygen atmosphere.

Fisher's pen famously accompanied Apollo 7 astronauts into space, and the rest is history.

As the saying goes, the future is now. Have you tried pressurized ink pens before? Let us know what you use them for in the comments below!