RFA - Redshift Hot Fire

Image: RFA One Redshift hot firing. Credit: RFA

Today, RFA announced on X that they successfully conducted a hot-fire test of the third stage of the RFA One rocket.

Link to announcement

Introduction

Before we dive into this article, if you're unfamiliar with the RFA One or need clarification on "Redshift," please read this informative article: RFA: The Automotive Approach to Rockets.

At 4 p.m. on July 17th, RFA announced on X, "All good things come in threes. Keep an eye on this account today..."

I speculated that this could be them announcing RFA One Reusable and RFA One Max, making three versions of RFA One. Alternatively, I thought it might be the construction of two additional launch sites.

However, I was completely wrong. One of our readers, @Ownitt_UK on X, guessed correctly - it was a static fire test. Well done!

Previous static fires

RFA said, "All good things come in threes". What do they mean by this?

Difference between a hot fire and static fire

A static fire is generally a shorter-duration burn meant for monitoring the engine's performance. It allows engineers to verify the results and overall stability while the rocket remains on the ground. On the other hand, a hot fire is usually a reenactment of the official mission, following the mission profile closely.

First-stage static fire

Image: RFA One First Stage static firing. Credit: RFA

On May 16th, RFA performed an unannounced static fire of their first stage vehicle. The static fire lasting for 20 seconds was a success.

The RFA One first stage, equipped with 9 Helix engines, holds the record for the most engines on a European rocket to date.

Second-stage hot fire

Image: RFA One Second Stage hot firing. Credit: RFA

On June 2nd, RFA performed a hot-fire of their second stage. After 280 seconds, the hot fire test was classified as a success.

The successful hot fire of the Helix engine represents the first time that a privately developed European staged combustion engine has been successfully hot-fired.

Third-stage hot fire

Image: RFA One Redshift hot firing. Credit: RFA

Today, RFA announced that they successfully completed a hot-fire test for their third stage, Redshift.

Redshift, which is powered by the in-house developed Fenix engine, ran for 280 seconds, and no damage could be observed, meaning the test was a success! The 3rd stage is now qualified and will be integrated into RFA at SaxaVord Spaceport later this year.

Technical specifications

Redshift is RFA's OTV for RFA One. It is powered by the in-house-developed Fenix engine, which produces 1.5kN of thrust. Fenix uses a green nitromethane-based bi-propellant system. When paired with the correct oxidizer, nitromethane acts as a hypergolic fuel, meaning it instantly combusts upon contact with the oxidizer. Hypergolic fuels are preferred in space capsules and OTVs due to their reliability, simplicity, and high thrust output.