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

chrisyuen3
Jul 2
2 min read

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.

From left to right: Landon Kamps (Letara Co-CEO), Tsutomu Uematsu (Uematsu Electric CEO), Kojiro Hatada (ISC CEO), Shota Hirai (Letara Co-CEO)

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)