Comparison of fixed, mobile and partially mobile launch sites

Comparison of stationary, partially mobile and mobile cosmodromes. Comparison of stationary, partially mobile and mobile cosmodromes.



Author: Igor Makarov.


Part 3


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The flying cosmodrome (from the side of the aircraft) has the advantage over the ground location of mobile cosmodromes (implying the offshore platform), because the latter (the sea platform) is in the troubled waters of the Pacific and must correct its position relative to the equator, in addition, the offshore platform has a partially restricted zone Launch (due to rocket debris, and also the presence of civil vessels in this area). The aircraft can be moved to any point on the planet from where it will be possible to launch the missile, in addition, it can be done in the shortest time.

For comparison, the launch of a ground-based platforms (eg Baikonur Cosmodrome), has significant negative consequences for the realization of such a platform to launch: the most favorable slope when you start from the cosmodrome is 51O degree - it gives the greatest acceleration booster. Compared with stationary aircraft cosmodrome favorably with his mobility and ability to deliver the booster directly to the place where the missile was produced to the point of its launch. To illustrate the benefits of air penalty author of the work here is an example.

The main advantage realized by the Pegasus air start system, currently the only provider of air launch into orbit, is the flexibility of the system. Air launch into orbit gives the potential to dispose of an aircraft such as launch on demand, and is also less affected by such starting components as the weather. This allows an aircraft to fly relatively to the weather conditions as well as to fly in the best starting points. Another advantage includes a reduction in the range of national restrictions on the schedule of launches, minimum requirements for the launch site, the requirements for range and flight safety and equatorial launch are reduced.

One of the advantages of an air start is the huge savings in rocket fuel. This is because the airplane is capable of raising the rocket to a height much more economically / more efficiently using turbojet engines that do not require the supply of an oxidizer on board. This allows the launcher system to save an extreme amount of mass that would otherwise be used for fuel, thus reducing the overall size. Then a large part of the total mass of the rocket can be utilized by a payload, thereby reducing the cost of launching the payload. Running from the height also adds a significant gain in the technical characteristics (EFFICIENCY) of the rocket. High horizontal speed provided ​​aircraft missile provides high initial velocity vector and reduces the growth rate, which is required for entry into orbit. High speed can reduce the requirements for the growth rate to 15% as compared to the vertical start.

It may seem at first glance that the airplane is the accelerator to increase the payload. Really into the "Air Launch" is primarily used to reduce the cost. 10 000metriv is only about 8% minimum height required to release the temporarily stable orbit, and 4% of the height of a generally stable low orbit of the earth. Airliner is designed to speed about 0.8 Mach it's about 3% of the orbital velocity.

The only reason for the postponement of the launch is the traditional weather. Pegasus Rising to a height of 10 thousand. Meters he gets beyond the troposphere to the stratosphere. Traditional weather is bounded by the troposphere and the cross winds at the height of 10 thousand. Meters is much softer. Thus, at an altitude of Pegasus is largely protected from the bad weather caused delays the start, and the related costs. (Bad weather is still a factor in the take-off, climb and flight to the starting point).

Air start reduces infrastructure costs. No explosion-proof starting table, blockhouse or associated equipment is required. This allows takeoff from various bases, mainly limited by the requirements of the payload for its provision and preparation. The aircraft's flight range allows launch from the equator, which increases the capability and is a requirement for the orbits of some missions (projects). Launches from the shores of the ocean also reduce insurance costs, which are often large for booster fueled with volatile fuel and an oxidizer.

Running from a height allows more effective, hence cheaper first-degree nozzle. Its expansion factor can be designed for low-pressure external (streamlined) air without the risk of separation of flows and instability in low-altitude flight. A high-altitude nozzle of increased diameter would make it difficult to control the thrust vector. And with reduced lateral winds, the tail stabilizers can provide sufficient controllability of the first stage of the missile's flight. This allows you to make a fixed nozzle, saves money and weight, unlike a nozzle with a swivel joint.

In recent years, this method run on a low Earth orbit at under certain conditions (for satellites of relatively small mass output at low orbits) is gaining popularity (has implemented projects and more projects many companies are considering this type of startup) due to the high economic efficiency and mobility (not required construction space centers).