Q: Beyond kicking the tires and flying a couple of trips around the pattern, why do you need to test Eve and gather so much data?

A primary reason for doing flight test on Eve is to inform our models. We have the ability to model our vehicle in terms of aerodynamics, loads and systems. Our engineers are able to use these computer models to predict how the vehicle will perform in different phases of flight. So, for flight tests, we actually go out and fly very specific conditions, gather data from the vehicle, such as airspeed, altitude, and various other aircraft parameters. Then the engineers look at the data and determine things like; to what degree did the wing bend or not bend? Our engineers take all of that information and update their models because, although we don't fly every possible situation, our computer models can and do!

And we also conduct what's referred to as a "functional check flight". It's a standard practice in the aviation industry and is always a key step after maintenance or modifications are performed on the aircraft. We check everything on the ground and then again in flight, during different maneuvers at different altitudes and temperatures – especially extremely cold temps.

Q: How do you get all that data from Eve? Is it like hooking her up to an EKG?

It is something like that, yes! As an example, we use "strain gauges," which are devices that measure stresses and strains. We have a number of strain gauges, and we put them on specific areas of the wing, the landing gear, the tail surfaces, and along the fuselage. They measure different areas on the aircraft, and when we do a maneuver that should stress the aircraft, our engineers collect the data and go back and then update their model. So yeah, there's a number of different gauges throughout the vehicle. We also measure the stuff you would normally measure – attitude, airspeed, altitude. We have a data system that collects all of that information and puts it onto a drive. We can also send that information down to our control room so we have engineers that watch in real time as we're doing this, and they can see exactly what the aircraft is doing as we're flying.

Q: Pilots say every plane has its own flying characteristics. After modification, will Eve fly differently?

After we go through and re-rig our flight controls, it won't be exactly the same. We have specifications, of course, so we know the aircraft will fly properly, but it may not be exactly as it was before. Now, for the pilot, you may or may not notice it, but of course, that's why we get the data. The test pilot has an opinion, but the data has the facts!

Regardless, I'm always impressed by how well Eve performs, especially when it doesn't have to carry a spaceship. For such a large aircraft, it's got a lot of get up a go! On take-off it practically leaps off the ground. And that's not even at full power! Now remember, it has two fuselages and that does take some getting used to because we're not sitting in the center of the airplane.

Q: The biggest change to Eve is the launch pylon, the assembly in the center of the wing between the two fuselages, that cradles VSS Unity and releases it. It's the primary role Eve plays – to carry our spaceship to launch altitude. Is it possible to test the pylon without actually attaching Unity to it?

Yes! One thing we will do is take it out – without any spaceship attached to it – up to high altitude, cold-soak it (make sure everything operates in extremely cold temperature), then we actuate the hooks that would normally attach to the spaceship and collect data on how they performed.

Q: After Eve passes its flight test, when will it head back to Spaceport? And is VSS Unity ready to go for a ride?

Yep, Unity is ready and waiting! After we complete system checks during initial flight test, Eve will fly what we call a ferry flight to New Mexico. The team is excited to see Eve and Unity reunited again, and we have some more testing to do with the mothership and spaceship combined – including more ground testing, glide and powered flight to complete the required validations of the vehicle's modifications.

Virgin Galactic Completes Glide Flight From Spaceport America

Company to Prepare for Rocket Powered Spaceflight Pending Data Analysis

"Releasing Unity for a glide flight today (April 26) is one of the final steps towards commercial spaceline operations," said Mike Moses, President of Spaceline Missions and Safety at Virgin Galactic. "The ability to conduct glide flights – allowing us to gain critical performance metrics without the need for rocket- power – is one of the benefits of our distinctive flight system. The data from this validation flight will clear the way for our return to space and, ultimately, lead to the launch of commercial service."

Mission Objectives

• Evaluate the performance of the spaceship in the glide phase of flight, following the modification period.

• Continue evaluating the handling qualities and flight controls of the spaceship.

• Gather data on the new mothership pylon with the spaceship attached during standard climb and release.

Next Steps

• Today's successful glide flight closes out the final validation test points, in addition to data gathered in a mated configuration flight last week.

• The data collected today will be analyzed over the coming weeks. Pending data analysis this will clear our vehicles to return to spaceflight.

• The next mission will be a rocket-powered spaceflight. This flight will carry two pilots and four Virgin Galactic mission specialists in the cabin to assess the customer experience and ground-based training prior to the launch of commercial service, expected in Q2.

In Flight Facts: Unity's 24th Mission

• Take-off Time: 06:53 MST
  
• Altitude at Release: 47,000'
  
• Release Time: 07:47 MST
  
• Landing Time: 07:56 MST
  
• VSS Unity Pilots: CJ Sturckow, Nicola Pecile
  
• VMS Eve: Kelly Latimer, Jameel Janjua