Hybrid Rocket Milestone: Letara's Camui-style HTPB Engine Achieves 5000N Thrust and 7 Seconds of Stable Burn at World’s First Firing Test

On Tuesday, July 1, 2025, Letara Ltd (Head Office: Sapporo, Hokkaido, Japan; Representatives: Shota Hirai and Landon Kamps) conducted a successful engine firing test of its hybrid rocket engine at its test facility in Akabira, Hokkaido together with Innovative Space Carrier (headquartered in Chuo-ku, Tokyo; Kojiro Hatada, President; hereinafter referred to as “ISC”). The test confirmed two major performance goals: a sustained 7-second burn and thrust output of 5000 newtons. Reaching this level of thrust marks a critical milestone, providing essential data for the reliability of Letara’s engine technology. Letara is currently developing a rocket engine capable of delivering a 100kg-class satellite to a 500km orbit, targeting a launch demonstration by 2028.

The engine used in this test was fueled with HTPB (Hydroxyl-Terminated Polybutadiene), a synthetic rubber material. This choice enables faster development cycles and the ability to produce powerful, scalable, and cost-effective rockets. Leveraging HTPB gives Letara a major competitive edge in the future of space transportation by reducing development time and accelerating technology maturation.

HTPB also enables the design of rockets using a single large engine block, allowing more payload, such as satellites, to be delivered to orbit, while also significantly reducing launch costs. This represents a new and promising alternative to the plastic-based fuels utilized thus far. Notably, this test marks the world’s first successful firing of a CAMUI-type hybrid engine using HTPB fuel.

The 7-second burn duration was sufficient to confirm stable combustion behavior and to generate large volumes of high-resolution internal engine data. This data will be used to refine the engine development process for a successful launch demonstration in the next few years. This would mark a major milestone in Japan’s spaceflight history.

‍What is a CAMUI-Type Rocket?

The CAMUI rocket fuel design features multiple aligned hollow cylindrical channels made of solid fuel pucks to maintain consistent burn surface area, enabling stable long-duration combustion. Compared to conventional hybrid rocket fuel styles, this design offers easier combustion control and longer burns. HTPB-based CAMUI fuel also burns faster and produces more thrust than traditional plastic fuels of the same size, allowing for smaller, lighter engines without sacrificing power.

Letara’s co-founders Shota Hirai and Landon Kamps have a long history of CAMUI research and development at Hokkaido University, and their expertise continues to shape Letara’s engine technology today.

‍Firing Test Information

• Test Objectives
  • Verify ignition and combustion of CAMUI-type solid fuel using synthetic rubber
  • Achieve stable combustion for 7 seconds
  • Achieve thrust of 5000 newtons
• Test Results
  • Confirmed ignition and continuous 7-second burn using synthetic rubber fuel
• Test Date
  • Tuesday, July 1, 2025
• Location
  • Letara Test Site (Uematsu Electric Co., Ltd., 230-50 Kyowa-cho, Akabira-shi, Hokkaido)

‍Innovative Space Carrier Inc.
‍CEO: Kojiro Hatada
Head office: 1-4-1 Nihonbashi, Chuo-ku, Tokyo
Established: May 2, 2022
Business description: Commercialization of innovative space transportation systems.
URL: https://innovative-space-carrier.co.jp

Letara Ltd.
‍CEOs: Shota Hirai and Landon Kamps
Head office: 2-10, Hassamu 9-jo 10-chome, Nishi-ku, Sapporo, Hokkaido
Established: June 23, 2020
Business description: Development and provision of rocket and satellite propulsion systems.
URL:  https://www.letara.space

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