In our previous discussions (3 part series), we covered various methods to reach space without the use of rocket propulsion in its entirety. We have covered static, dynamic structures and use of projectiles.

Though we concluded the series, there is still one topic without which the discussion would not be complete. Today we will discuss about the spaceflight technology development company – SpinLaunch. This company is working on mass accelerator technology to move payloads to space.

Company Logo (Credits: spinlaunch website)
Company Logo (Credits: spinlaunch website)

Introduction

Founded by Jonathan Yaney in Sunnyvale, California in 2014, it aims to develop a kinetic energy space launch system that reduces dependency on traditional chemical rockets.  It has created an alternative method for putting 200 kilogram class satellites into low earth orbit. Unlike traditional fuel-based rockets, SpinLaunch uses a ground-based, electric powered kinetic launch system that delivers a substantially less expensive and environmentally sustainable approach to space access.

An Orbital Accelerator (Credits: spinlaunch website)

Technology

As such the SpinLaunch system’s historical predecessors are the centrifugal guns.

The technology uses a vacuum-sealed centrifuge to spin a rocket and then hurl it to space at up to 5,000 miles per hour (8,000 km/h). The rocket then ignites its engines at an altitude of roughly 200,000 ft (61,000 m) to reach orbital speed of 17,500 miles per hour (28,200 km/h). Peak acceleration would be approximately 10,000 G’s. If successful, the acceleration concept is projected to lower the cost of launches and to use much less power, with the price of a single space launch reduced by a factor of 20 to under US$500,000.

One can view the concept video here.

Challenges

The system presents unique engineering challenges as follows:

  1. Given a projectile weight of 1,000 lbs (approx 455 kg) a rotational speed resulting in 10,000 G’s, the spinning arm of the system will need to control approximately 20 million pounds of mass (This represents the projectile and counterweight, not counting the mass of the arm itself).
  2. When released from the centrifuge the payload will be immediately subject to immense heating through air friction and 72,818 lbs/ft^2 (approx. 3.5×10^6 pascal) of air pressure.
  3. If the system uses a counterweight its unclear how the spinning arm will manage the asymmetrical loading once the payload is released. If the counterweight is released at the same time as the payload, in order to maintain balance, it will be traveling with the same velocity and kinetic energy as the projectile itself, posing a significant threat to safety.

Despite the above challenges, SpinLaunch conducted the first vertical test of their accelerator at 20% of its full power capacity. This test accelerator (at Spaceport America in New Mexico) is 108 ft (33 m) in diameter, which makes it a one-third scale of the operational system that is being designed.


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