WASHINGTON (States News Service) - Lockheed-Martin released Friday an early image of its re-designed VentureStar launch vehicle, which boasts an external payload bay not found on earlier models. This will result in greater fuel efficiency.

Lockheed-Martin's top executive on VentureStar, Vice President Jerry Rising, told States News Service and space.com that the new configuration has already been wind-tunnel tested and should provide greater mission flexibility for the proposed re-usable vehicle.

"As we continued... the packaging efficiency was maximized by taking the payload bay out of the vehicle altogether," Rising said.

"It did increase drag," Rising said, "[but] we're more concerned about stability and controllability. Drag is an issue of course, but with this vehicle, we're able to fly a lifting trajectory -- the maximum lift-to-drag ratio."

VentureStar, like its under-construction prototype, the X-33, will take off vertically like a rocket and then land horizontally like an airplane.

Rising said the size of the payload bay remains the same - 15 feet in diameter and 53 feet long - but moving it outside the craft may allow it to be wider and longer if needed.

"We feel we could safely increase the width a little bit and increase the length up to 63 feet," Rising said. Details may not be exact until the design is finalized next October.

The re-design may make for easier integration with NASA's proposed Crew Return Vehicle (CRV) for the International Space Station (ISS). NASA is developing the un-powered vehicle primarily as a lifeboat that will be used to ferry a crew back to Earth in the event of a space station emergency. Current plans call for it to be transported to the ISS in either the Space Shuttle or VentureStar payload bays.

With the new configuration, Rising said, VentureStar could just remove the payload bay and clamp the CRV directly onto the craft's back.

The VentureStar design schedule has not been delayed at all by the new configuration, Rising said. The vehicle remains "very traceable" to the X-33, he said, meaning that the small-scale prototype will still give a good demonstration of many of VentureStar's technologies and concepts.