## The passion. Why not building a drone?

Drones have seen a quick development in the last decade. Many are already commercialized like any other technological toy of our days. As prices get lower and lower, they spread around the world sometimes creating serious concerns about their safety and possible privacy violations.

Why start to build a drone then?

The ones that can be bought are not exactly what you’re searching for. Adapt it as you want depending on the mission it has to accomplish.

Test personal skills and see how far can you go when in comes to build a drone. And why not, learn a lot of new things about robotics.

Want to start a business based on the use of such technology. Give an important aid to the human society by offering an usefull service.

Etc. Of course add many other reasons, different for each one of us…

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Many would like to build their own drone. Let’s say it’s a passion. But as Mike Rowe once said Don’t follow your passion, but always bring it with you. He’s just a Tv presenter, but I found the idea quite interesting.
Well drones are not only complicated but also quite expensive due to necessary tests and failures. Make sure you have all you need and the ambition necessary to fulfill the mission before starting something you’re not able to do.

Annunci

## Greece, the use of a secondary currency

Greek government does not want to take into account the possibility of using a secondary currency to solve the banks liquidity crisis due to BCE decision to stop ELA.

They have 5 more days till sunday, but it’s clear that if they’ll not find an agreement quickly a second currency could actually be necessary in order to sustain the internal market. This can be just a temporary choice, or a long term solution.

The first case allows to gain time, and the currency will keep be relatively stable compared to euro, since people will expect to get back euros in the future. The EU will need to deal with a less dramatic humanitarian crisis.
Instead the use of the currency as a long term solution may open the door to inflation.

## Greece after Varoufakis “minister no more”

With Greece falling in deep economic uncertainty, Italy will be the next target on the market. But at least after the Greek referendum it is clear that the european and perhaps world’s economic situation is dramatic. As finance tries to survive, social instability sets to be become a commune condition worldwide.

Originally finance should have helped the economy to defend the social stability by redistributing wealth and encouraging new ideas and progress. But something went terribly wrong…

## Why are chemical rockets so useful when it comes to leaving the planet?

In order to reach a stable orbit it’s necessary to generate enough thrust to overcome the resistances, mainly gravitational and aerodynamic. We therefore consume energy, but what is important is how we consume that energy.

A thrust that is equal to the gravity force would not move the rocket at all. It requires an infinite quantity of energy just to maintain the condition of equilibrium.

Propellant is the main component when it comes to weight before take off. As the rocket becomes heavier, it will require more and more propellant. Technological limits indicate an optimal condition that allows to leave the planet, and the gravitational field, quickly consuming a reasonable quantity of propellant.

Usually to optimize the fuel consumption, rockets are divided into stages. This allows to get rid of components, and weight, that aren’t useful anymore.

$I_{sp}=\frac{I_{tot}}{m_{f}g_{0}}$
$I_{tot}=\int_{0}^{t}Tdx$

Chemical rockets have smaller specific impulse compared to electrical propulsion, which is usually choose for orbital maneuvers. That because in space we can build up necessary accelerations in weeks, months or perhaps years. In fact missions last for very long periods and slow accelerations build through electrical systems bring the advantages of having lighter space systems that can cover major distances.

Rockets are used because of the high power they can generate. This way it’s possible to leave the planet in the shortest time at maximum efficiency. Though they have a very short lifetime compared to the electric propulsion systems.