Small Launch Vehicles

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Technology Roadmap Sections and Deliverables

  • 1SLV - Small Launch Vehicles

Roadmap Overview

Small launch vehicles (SLVs, also called "Small launchers" or "Small-lift launch vehicles") are a category of orbital launchers capable of carrying a payload of maximum 2000kg* to LEO (Low Earth Orbit). Half a century ago, many families of launch vehicles have started as small launchers, as prototypes, and have led to today's large landscape of heavy launch vehicles (Ariane V, Falcon 9, Soyuz, Delta IV...). Today, the growing market of small satellites (below 500kg) - including, notably, LEO constellations projects and cubesats - pushes towards dedicated small launchers. This trend started in the 1990s and considerably accelerated in the 2010s with the development of a broad ecosystem of SLV startups. In comparison to conventional (heavy) launch vehicles, SLVs have: a higher scheduling flexibility, a higher launch frequency, a much lower total cost but a higher cost per kg of payload.

Categ.jpg Ng12timeline.jpg Rocketlab2.jpg Electron illustration.png

Captions: (1) Classification of SLVs among launch vehicles on their payload capacity. Source: SpaceCapital. (2) Launch profile of a typical SLV mission with 2 stages and non-reusable rocket (Antares here). Source: Northrop Grumman. (3) Launch of the Electron SLV (Rocket Lab). Source: Rocket Lab. (4) System decomposition of a SLV (Electron here). Source: Rocket Lab.

*: Diverse definitions exist. Some define small launchers as limited to 1 ton instead of 2 tons, some also define a lower boundary of 500kg under which launchers are called 'micro-launchers'.

Design Structure Matrix (DSM) Allocation

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The technology hierarchy demonstrates that such technologies as metal 3-D printing and modulable launchpads are supporting the development of small launchers. Initiatives and development plans for these technologies enhance small launchers by increasing their reusability, launch rate, scheduling flexibility, and reducing their cost per kilogram to launch payloads into orbit.

TechHierarchy.png

Roadmap Model using OPM

We provide below an Object-Process-Diagram (OPD) of the 1SLV roadmap. This diagram captures the main object of the roadmap, its decomposition into subsystems (engines, avionics, payload...), its characterization by Figures of Merit (FOMs) as well as the main processes and actors involved.

Opm.PNG

An Object-Process-Language (OPL) description of the technology is auto-generated and given below:

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Figures of Merit

Figures of Merit (FoM) used to evaluate small launchers are very similar to the FoMs of conventional launch vehicles, but they have redefined the priorities among these. Typical FoMs for small launchers are:


Launch Frequency [launch/month]

Reliability [% of successful launches]

Payload mass capacity [kg of payload to 500km LEO]

Total cost [$], Cost per kg [$/kg of payload to LEO]

Reusability [Number of reuse cycles]

Scheduling flexibility* [weeks or months or years] (Sometimes called Responsiveness, it is the duration between the launch window and the notification of its flight parameters - orbit, latitude, date, etc.)


In general, small launcher companies aim for very high launch rates (weekly instead of monthly), high scheduling flexibility (months instead of years), and low launch costs thanks to significant economies of scale enabled by mass production. Some also leverage uncommon launch strategies (balloons, planes, catapults), but here we only include into our scope actual orbital launchers with launching pads on earth or on sea.

The following plots have been built using a database our team built and plan upgrade regularly throughout time. Main sources of information are SpaceFund.com, Newspace.im and small launcher companies' websites and user guides.

LaunchChart.PNG Rate.PNG

Using a simple linear regression model, we can find a decreasing cost of: $$-2930.4\$/kg/year$$ This means that costs for launch are project to decrease by $2930.40 per year. This is a rough estimate and data is still being collected to make this model more accurate as small launchers are relatively new and data is scarce.

The physics of launchers is governed by the Rocket Equation:

$$\Delta V = v_e \log(\frac{m_0}{m_f})$$

<math> \Delta V </math> is the change of velocity available to the missile

<math> m_0 </math> is the initial wet mass

<math> m_f </math> is the (final) dry mass

<math> v_e </math> is the effective exhaust velocity