Air-breathing hypersonic powerplants are typically fighter-jet engine-sized. But Velontra has just test-run an 11-inch diameter, five foot-long turbojet that will be the core of its Bronco hypersonic propulsion system.

The Ohio-based company was launched in 2021 with a goal of one day producing a low earth orbit spaceplane to serve the satellite launch market. Like every other would-be hypersonic transport/launch developer, it will pursue government and defense technology contracts on the way there.

The small size of the Bronco propulsion system makes Velontra stand out. A ready-made hypersonic engine for smaller drones and other air vehicles is of obvious interest to a variety of national defense and commercial organizations, particularly if it can be delivered cost-effectively.

Velontra leaves little doubt on that point, claiming that the unit cost for Bronco will be “less than $200,000”. The company was started with cost and rapid development firmly in mind taking inspiration from SpaceX says Velontra CTO, Joel Darin.

“We don’t want to just ask investors to trust us with a ton of money and ten years later see if our idea works or not. We want to produce actual products at each stage that develop the technology we’ll eventually need. This small application lets us develop a product at a fraction of the cost [of full scale hypersonics] that people will buy.”

According to Darin, large hypersonic propulsion system testing in full-scale wind tunnel facilities can cost up to $50,000 per hour. “We’re paying $300,000 to get two to three months of testing,” he says. “The development is much cheaper but the lessons we learn are scale-able to bigger applications.”

Applications, particularly drone and test vehicle roles, are something Velontra expects to rapidly move its small hypersonic propulsion system into. The company has already taken the first step in doing so in signing a contract with hypersonic transport developer, Venus Aerospace to provide four Bronco propulsion systems to power a small-scale near-hypersonic UAV which Venus will use to test its own hypersonic propulsion technology.

I previously wrote about Venus’ efforts to realize its own hypersonic airliner and the likely defense technology development/sales route it will take to get there. I was unable to get confirmation of the supplier contract with Velontra from Venus by publication time.

However, it would seem reasonable that the Texas company may subcontract the air-breathing powerplant for a hypersonic test vehicle to perfect its own liquid-propellant rotating detonation rocket engine (RDRE). Darin asserts that it is remarkable for a seed-phase startup like Velontra to already have a hardware contract in hand. He also alluded to the model it establishes for his company.

“They’re [Venus] like an airframer buying our propulsion system,” Darin says. That could be a replicable business proposition for the small Ohio firm (currently it has a dozen staff) if anticipated flight testing of Bronco late this year in Venus Aerospace’ hypersonic drone is successful. Darin did not disclose the value of the Venus contract but did affirm that Velontra currently has a total of $2 million in contracts for Bronco.

A successful flight test and program with Venus would logically be watched by DoD’s science and technology community. Darin told me that Velontra has four Phase 1 research contracts with the Air Force’s AFWERX innovation hub although the organization confirmed only two Small Business Technology Transfer (STTR) projects.

Nevertheless, compact hypersonic propulsion systems will be avidly sought by the defense community which has repeatedly expressed its desire for a quick expansion of hypersonic development test resources. The Pentagon’s National Security Innovation Capital (NSIC) organization has already demonstrated such appetite, laying out $1.5 million in development funding earlier this year for a 3D-printed hypersonic rocket engine called “Mjölnir” from Seattle-based New Frontier Aerospace (NFA).

The size of Mjölnir isn’t clear but it appears to be small-ish. The engine has yet to run (testing is slated for 2024) and it is apparently not an air-breathing system. That Bronco is an already-tested, air-breathing hypersonic propulsion unit speaks to its advantages.

Its cost advantage derives from using an unconventional off-the-shelf core. Rather than a full-fledged turbojet engine like the GE J85 that hypersonic developer Hermeus uses in its Chimera powerplant, Bronco makes use of a small turbojet used in military target drones and hobbyist radio-controlled jet models – Atlanta-based PBS
PBS
Aerospace’ PBS TJ150.

In stock configuration the small engine provides 337 pounds of thrust. The Bronco design adds a Velontra-developed afterburner and a ramjet to get the system to hypersonic speeds. Joel Darin says the company is shooting for 500 to 600 pounds of thrust from the TJ150 core, enough to propel air vehicles with 700 to 1000 pounds dry weight to supersonic speeds and then to accelerate to hypersonic velocities as Bronco’s ramjet comes online.

The combination (including the ramjet) was tested this Spring in Purdue’s Zucrow Laboratories in a High Pressure Combustion Lab. Velontra CEO, Robert Keane III, said the Bronco was tested, “at speeds over Mach 4.5 and altitude simulated over 100,000 feet, and it successfully screamed through vigorous testing with flying colors.”

The results, combined with a real piece of hardware, have generated significant enthusiasm Darin says. “We’ve gotten nothing but good reaction to the test and even the [general] idea before that. With the [test] milestone we hit recently, we can start making the rounds, reminding [potential investors] we’ve done what we said we were going to do.”

As noted, investment could come from a variety interested parties including companies looking to meet the U.S. Air Force’s desire for attritable Collaborative Combat Aircraft (CCAs) for which the first performance metric is supposed to be cost. Low cost with hypersonic capability would indeed be big.

The next phase will see Velontra work towards optimizing Bronco for thrust, thrust vectoring, and durability as well as pushing to first-flight in the Venus Aerospace UAV Derin says. Success in such near-term development could attract both more attention and more money though Velontra’s CEO insists the company’s goal is to learn as quickly as possible by selling Broncos.

“This is not something that looks cool to raise money off of. This is a product.”