UPDATED Washington: The Raytheon-Boeing team building took another significant step ahead of Lockheed Martin in the $5 billion Joint Air To Ground Missile competition, successfully testing its rocket motor for helicopter flight.

Raytheon officials said the fifth and sixth rocket engines were subjected to temperatures as low as -65 Fahrenheit and successfully fired after being subjected to helicopter motion and vibration stresses on July 13.

After our story first appeared this morning, Lockheed sent us an update, noting they also had successfully tested their rocket engines. Lockheed is actually a bit ahead of Raytheon in this stage of testing. Lockheed has already tested their rockets to helicopter stresses, as well as those similar to being mounted on an F-18 in combat.

“The results were exactly as we predicted,” a Raytheon-Boeing program official said. The July 13 tests were considered particularly daunting because of the low temperatures. Many solid rocket fuels will “glassify” at such low temperatures. If that happens, the engine explodes when fired.

One of the most interesting details about the JAGM engine requirements is that the engines must be almost smokeless, which industry officials say is technically challenging.

This marks the sixth straight successful for the Raytheon-Boeing JAGM team during this round of testing. The next set of tests involve the greatest stress since they will mimic the conditions of a rocket mounted on an F-18 in combat.

Lockheed sent us a press release Wednesday morning:

“These tests prove we can meet the more stressful environmental requirements necessary for fixed-wing aircraft with the same motor we are designing for rotary-wing use,” said Frank St. John, vice president of tactical missiles in Lockheed Martin’s Missiles and Fire Control business. “This takes us one step closer to demonstrating we can deliver one rocket motor for all platforms, which will yield significant sustainment savings and increased operational flexibility.”

Lockheed had been silent about its test results for some time. That silence began after a third Lockheed test at White Sands Missile went awry in September last year. Lockheed missed on two out of three tries during the government-sponsored testing. The company continued testing on its own dime after that and presented the data gathered to the government.