The Vector-R P-19H engineering model during an aborted launch in April. The rocket flew what the company said was a successful, but low altitude, test flight May 3. Credit: Vector

Updated May 5.

WASHINGTON — Vector, one of several companies currently developing small launch vehicles, said it successfully flew a prototype of its vehicle in a low-altitude test flight May 3.

The company, previously known as Vector Space Systems, said an engineering model of its Vector-R rocket, designated P-19H, lifted off from a pad in California’s Mojave Desert at around 3 p.m. Eastern May 3. The test took place after the computers aborted an earlier attempt April 6 because an unspecified problem in the final seconds.

The company, in a statement, declared the launch a success but provided few technical details about the flight. Company spokeswoman Sarah Nickell said that the planned maximum altitude for the rocket on this launch was 1,370 meters, but said later that the company will not release the flight’s actual peak altitude.

The Vector-R vehicle under development by the company will have three 5,000-pound-force engines in the rocket’s first stage, and one smaller engine in the second stage. It is designed to place up to 60 kilograms into low Earth orbit.

The vehicle that launched from Mojave had only one engine in place, and photos of the rocket the company posted on social media earlier this year suggested the rocket had only very small propellant tanks. The P-19H designation appears to be a holdover from Garvey Spacecraft Corporation, which tested a small suborbital rocket called the P-19 in 2014. Vector formally acquired Garvey in mid-2016.

That design for this prototype was an intentional choice in order to incrementally test the vehicle, James Cantrell, chief executive of Vector, in a May 4 phone interview. “It’s an incremental development approach that gradually adds more and more complexity and performance to the vehicle as we go along,” he said. The use of small propellant tanks, he explained, limited the vehicle’s performance for this flight and allowed them to meet Federal Aviation Administration regulations for a waiver from a commercial launch license.

He contrasted that with the approach taken by many other launch vehicle developers, who first fly their vehicle on a full-up orbital mission. “In my experience, people do that because they see that as the shortest and most inexpensive path to getting to that point,” he said. “My theory is that it’s actually not.”

A second test flight is planned to take place in about two months, Cantrell said, and will feature larger propellant tanks to allow the vehicle to fly supersonic. A third test flight, intended to demonstrate the vehicle’s thrust vector control system, would take place two months after that. He said he expects to carry out five to six test flights of Vector-R prototypes, culminating in an orbital test flight.

The company disclosed in April that it raised a “bridge round” of $4.5 million to support company operations until it can close a larger Series A round later this year. The company is also planning to build a new headquarters and vehicle factory in Tucson, Arizona, where it is based.

The company put a model of its Vector-R rocket on display at the Kennedy Space Center Visitor Complex in Florida last month. The company is considering performing launches from a pad at Cape Canaveral. Vector also said it will carry out a suborbital launch this summer from a site in Camden County, Georgia, where local officials are seeking to develop a spaceport. An environmental assessment for the proposed spaceport, a key step in the FAA launch site licensing process, is underway.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...