Draper engine – Behind The Black

Ursa Major wins contract for hypersonic test flight of its Draper rocket engine

May 2, 2025 9:29 am Robert Zimmerman

The rocket engine startup Ursa Major has now won a $28.5 million contract from the Air Force Research Laboratory to do a hypersonic test flight using its Draper rocket engine.

The contract, announced May 1, covers both the flight demonstration and integration of the engine into a test vehicle, with work scheduled through early 2027. The project aims to advance U.S. capabilities in hypersonic weapons, a category of defense systems that has become a top Pentagon priority amid competition with China and Russia.

The Draper engine is designed to produce 4,000 pounds of thrust and was developed by Ursa Major with U.S. Air Force funding. Its key differentiator is its use of storable, non-cryogenic propellants — specifically a kerosene and hydrogen peroxide combination — that remain liquid at ambient temperatures. This contrasts with traditional rocket engines that rely on liquid oxygen, which must be kept at ultra-low temperatures and handled with complex cooling infrastructure.

It certainly does appear that the Pentagon is ramping up its hypersonic research with a slew of contracts to many different new commercial space startups. In addition to this deal, Rocket Lab, Varda, and Stratolaunch have won contracts for similar hypersonic testing, with Rocket Lab winning the most. No wonder a new company like Radian (see previous post) is switching its focus toward this research.

Air Force awards Ursa Major rocket engine development contact

May 23, 2023 9:13 am Robert Zimmerman

The Air Force Research Laboratory (AFRL) has awarded the rocket engine startup Ursa Major a contract to develop two different rocket engines.

Under the contract, the Colorado-based firm will build and test a prototype of its new Draper engine for hypersonics, and further develop its 200,000-pound thrust Arroway engine for space launch.

…Under the AFRL contract, for which neither the lab or company provided a value, Ursa Major will also build a dedicated test stand for Draper and plans to hotfire the engine within 12 months.

Arroway, on the other hand, is a reusable liquid oxygen and methane staged combustion engine for medium and heavy launch vehicles. Ursa Major first announced development the 200,000-pound thrust engine last August, explaining that when clustered together, Arroway engines could replace the Russian-made RD-180 and RD-181, which are no longer available to US launch firms.

According to Ursa Major’s press release, the AFRL contract will allow further development of Arroway with a hotfire expected in 2025.

Ursa Major already has several contracts for its smaller Hadley engine, from the rocket startups Phantom, Vector, Astra, and the Air Force, and has built more than a hundred so far. The Arroway meanwhile is being developed as an American replacement for the Russian engines used by Northrop Grumman in its Antares rocket.

All in all, it appears Ursa Major is becoming a major challenger to Aerojet Rocketdyne, which in recent years had a lock on most government contracts for rocket engines. That lock resulted in very expensive engines that took years to build. The government (and others) are now finding someone else to provide this service at a better cost and far more quickly. We shall see whether Aerojet Rocketdyne responds to this competition properly, or goes the way of the horse carriage.