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The engine in the June 4, 2024 headline was not a scramjet and it was not tested in hypersonic flight. It was Ursa Major’s Draper, a 4,000-pound-thrust liquid rocket engine that completed an initial hot-fire campaign in May 2024. Designed for hypersonic test vehicles, missile-defense targets and other tactical systems, Draper uses storable hydrogen peroxide and kerosene instead of cryogenic propellants.
The program has since advanced from engine testing to an integrated vehicle demonstration. Ursa Major reported more than 200 Draper hot-fires in 2025, a full-duration static fire later that year and a supersonic flight of the Draper-powered Affordable Rapid Missile Demonstrator (ARMD) in March 2026. Those milestones are significant, but the public information does not establish a sustained Mach 5 flight or operational deployment.
What was actually tested?
Draper was tested at Ursa Major’s facility in Berthoud, Colorado, during a series of ground hot-fires. In a hot-fire test, an engine is mounted to a test stand and operated with live propellants. Engineers measure performance and examine ignition, combustion, controls, thermal behavior and hardware durability.
That is different from a component test, which evaluates items such as valves or injectors; an integrated static fire, which operates the engine installed in a complete vehicle while the vehicle remains restrained; and a flight test, which exposes the complete system to aerodynamic loads, vibration, guidance demands and the actual flight environment.
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The 2024 event was an engine-level ground demonstration—not a hypersonic missile launch, an operational weapon test or proof that a complete vehicle had sustained speeds above Mach 5.
Ursa Major introduced Draper publicly in May 2023 under development funding from the U.S. Air Force Research Laboratory (AFRL). The company’s technical description of Draper identifies it as a 4,000-pound-thrust, closed-catalyst-cycle engine intended for hypersonic-defense and tactical applications. The original New Atlas report was published on June 4, 2024.
Is Draper a scramjet?
No. Draper is a liquid rocket engine. A rocket carries both fuel and oxidizer, so it does not need to obtain oxygen from the atmosphere. A scramjet, by contrast, is an air-breathing engine: it uses atmospheric oxygen while maintaining supersonic airflow through its combustor.
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| Engine type | How it produces thrust | Key implication |
|---|---|---|
| Rocket | Carries fuel and oxidizer | Can operate outside the atmosphere and at low speed, but must carry oxidizer |
| Ramjet | Uses atmospheric oxygen and burns fuel after slowing incoming air to subsonic speeds | Needs an external boost to reach its operating regime |
| Scramjet | Uses atmospheric oxygen while combustion occurs in supersonic airflow | Can be efficient for high-speed atmospheric flight, but inlet, ignition, fuel injection and thermal management are difficult |
| Dual-mode ramjet/scramjet | Uses different combustion regimes during different portions of flight | Can cover a wider operating envelope, with added design complexity |
NASA’s hypersonics overview provides background on air-breathing programs such as X-43A and HIFiRE. Those systems should not be conflated with Draper.
How Draper’s propulsion cycle works
Draper uses hydrogen peroxide as its oxidizer and kerosene as its fuel. The peroxide is decomposed catalytically to create hot gas and oxidizing flow for the engine cycle. The resulting flow supports combustion with kerosene in the main chamber. Ursa Major describes this as a closed catalyst cycle.
The cycle is unusual in this context not because it is scramjet-like, but because it attempts to combine characteristics normally associated with different propulsion classes:
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- Liquid-engine control: A liquid engine can be throttled, allowing thrust to be actively adjusted.
- Restart potential: A restartable design could support multiple burns or maneuvering, subject to the final vehicle configuration and qualification.
- Solid-motor readiness: Storable propellants can avoid the long-term refrigeration needed for liquid oxygen or liquid hydrogen.
- Tactical packaging: The company presents Draper as a relatively compact propulsion option for constrained vehicles and test targets.
“Storable” does not mean maintenance-free or risk-free. Hydrogen peroxide is a reactive oxidizer that requires compatible materials, contamination control, concentration management and strict handling procedures. The more precise comparison is that Draper’s propellants are less logistically demanding than cryogenic combinations, not that they are harmless.
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Why use a rocket in a hypersonic system?
A rocket can generate thrust independently of atmospheric oxygen. That makes it useful for boost and acceleration, maneuverable test targets, missile-defense simulations and shorter-duration tactical missions. Throttle control and restart capability may also be valuable when a vehicle needs more than the largely fixed thrust profile associated with many solid motors.
The trade-off is oxidizer mass. An air-breathing vehicle operating in the atmosphere collects its oxidizer from the air, while a rocket must carry its own supply. For sustained atmospheric cruise, that can reduce the mass available for payload or fuel compared with an efficient air-breathing architecture.
Therefore, Draper should be understood as an alternative propulsion architecture—not a universal replacement for scramjets or solid rocket motors. A rocket may be preferable when readiness, controllability, range of operating conditions or test-target affordability matters more than the efficiency of long-duration atmospheric cruise.
What the 2024 hot-fire demonstrated
At minimum, the successful hot-fire showed that Draper had progressed beyond paper studies and isolated component development. The engine could be ignited and operated with its intended hydrogen-peroxide-and-kerosene combination, generating data for further maturation.
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It did not, by itself, demonstrate:
- sustained hypersonic flight;
- operation across a complete flight envelope;
- successful integration with a missile or test vehicle;
- terminal maneuvering or survivability against defenses;
- production readiness or battlefield availability;
- lower total system cost than competing propulsion systems; or
- superiority over scramjets, ramjets or solid motors.
Engine thrust alone also cannot establish a vehicle’s speed or range. Those depend on vehicle mass, drag, trajectory, burn duration, guidance, thermal protection and many other factors. Public information does not provide the initial test’s specific impulse, chamber pressure, mass, dimensions, burn duration, restart count or flight performance.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What happened after the original hot-fire?
The program’s later milestones make the 2024 test more than an isolated laboratory event:
| Date | Milestone | What it means |
|---|---|---|
| May 2023 | Draper publicly introduced under an AFRL contract | Established the engine’s intended role, propellants and cycle |
| May 2024 | Initial successful Draper hot-fire campaign | Engine-level ground demonstration |
| May 1, 2025 | AFRL awarded Ursa Major a $28,565,857 follow-on contract | Moved the program toward an integrated flight demonstration; Ursa Major reported more than 200 Draper hot-fires |
| December 1, 2025 | Full-duration static fire of the Draper-powered ARMD vehicle | Demonstrated integrated ground operation over the mission cycle, according to Ursa Major |
| March 12, 2026 | AFRL and Ursa Major announced an ARMD flight reaching supersonic speeds | Confirmed a flight demonstration and supersonic operation |
The follow-on contract is described in Ursa Major’s May 2025 announcement. The company’s reports cover the December 2025 static fire and the March 2026 flight demonstration.
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How significant is Draper?
Draper’s significance lies in its attempted combination of liquid propulsion control with tactical storable-propellant logistics. If the system proves reliable and affordable at vehicle scale, it could support more responsive hypersonic test targets and development vehicles, as well as selected tactical applications.
That promise still depends on more than engine operation. The complete vehicle must withstand vibration and aerodynamic loads, manage intense heating, guide and control itself, communicate as required and perform its mission reliably. A design optimized for a test target or missile-defense surrogate may also have different requirements from a long-range strike vehicle.
Ursa Major’s hypersonics portfolio page includes company positioning around Draper, flight readiness and Mach 5-plus applications. Such claims should be treated as company statements unless supported by detailed, independently available test data. Terms such as “low cost,” “green,” “safe,” “reusable” and “flight-proven” also need a defined scope: they may refer to an engine, a particular demonstrator or a broader product portfolio rather than an operational missile system.
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The “radical” aspect of Draper is its propulsion and logistics concept, not the creation of a new scramjet. It is a throttleable, potentially restartable liquid rocket using storable hydrogen peroxide and kerosene, developed for hypersonic-defense and tactical testing where readiness and control may outweigh the efficiency advantages of air-breathing cruise.
The May 2024 milestone was a meaningful engine hot-fire, but it was not hypersonic flight. By March 2026, the program had reached a reported supersonic flight demonstration through the ARMD vehicle. That is a stronger result, while still falling short of public proof of sustained hypersonic operation, production deployment or an operational weapon.
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