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Previous Vehicle Design by Dan DeLong

Illustration of Frequent Flyer design by Dan DeLong

The Lynx is not the first reusable launch system designed by XCOR’s Chief Engineer Dan DeLong.  He designed launch systems for Teledyne Brown Engineering, all of which emphasized reliability, simplicity, and low operating costs.  His efforts included two air-launched reusable vehicles, the Spaceplane and the Frequent Flyer, as well as work on NASA’s Shuttle C and a commercial expendable launch vehicle.

Spaceplane was a high capacity launch vehicle design, which would mount on a 747 Carrier and launch a six to seven ton payload to low earth orbit (LEO).  Spaceplane was proposed for low development cost, low cost to orbit, ease of launch and landing, short development time, and a high market value. It was intended as a joint enterprise between NASA and Industry, and would be built with existing components, including Space Shuttle Main Engine (SSME).

The potential applications of Spaceplane included personnel and materials transportation to Space Station, flight testing components for other programs, and commercial, scientific, and military satellite launches. However, the design was optimized for freight hauling.

The Frequent Flyer was designed to be launched from either a military cargo aircraft or a Boeing 747.  It was created primarily as a cargo-carrier, so it was not piloted by a human or encumbered with the weight and complexity of a pressurized cabin and life support systems.  If NASA wanted the Frequent Flyer to take passengers into space, it would carry them in a self-contained pod.  

The Frequent Flyer was intended to launch 600 to 1,000 pound satellites into low earth orbit.  In an engineering philosophy that has been maintained on the Lynx, DeLong emphasized reliability and low operational costs over wringing every last ounce of performance out of his designs.  For example, by using lower wing loading, he sacrificed some weight and speed, but was able to design a vehicle that did not need the Space Shuttle’s heavy, fragile, and expensive heat protection tiles for re-entry.

Teledyne Brown Spaceplane concept by Dan DeLong

DeLong found that while air launching confers advantages on orbital launch systems, these advantages are not always obvious and they do involve trade-offs.  “The contribution of the carrier aircraft to the launch vehicle’s actual altitude and velocity is actually pretty small. The release angle actually helps more than the initial altitude.” he said, but there are several other factors that significantly affect performance. These include the ability to design the engines to be more efficient because they do not need to operate in high density air.  In return for the greater complexity and cost of using two vehicles, air launching gives engineers more freedom in designing landing gear, wings, and other parts of the launchers that improve performance. Most importantly, the advantage of air-launching an orbital system is that it allows a single upper stage to make it to orbit without the nearly impossible difficulties of Single-Stage-To-Orbit (SSTO).

All of DeLong’s designs entail low cost operations.  And, while the Lynx is planned to take off and reach the edge of space on its own, DeLong’s earlier designs will certainly play a role when XCOR moves beyond the suborbital Lynx and builds a fully orbital launcher.

The bulk of the work was done by Dan on his own time, and in recognition of this effort Teledyne Brown assigned ownership and intellectual property rights to DeLong when he left the company. He gratefully acknowledges help and support from Ernst Stuhlinger, Scott Spearing, Ken Farnell, and Jim Richard.

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