Reply #11: I think it is a silly concept .....

[Trajan]

I am no astronautical engineer ... but ...

That thing is going to suck down SO much fuel during 'hover' operations, and without considerable a fuel storage structure, it seems unlikely to possess the robustness required of a reliable spacecraft system ... It would need to land with enough fuel to power the landing .. but what if they used more than expected during launch ??? .... It is also prone to crosswind effects during the landing phase which could topple the system near earth ...

I am not hopeful that Blue Origin can overcome those difficulties ... Elon Musk's "Dragon" @ Space X seems the most likely candidate for the first private human flight to orbit, but it will be a more traditional multi-stage system, and the capsule will land with an extremely nostalgic ocean splashdown ....

Here is a pic of the 'original' vertical SSTO : The McDonnell Douglas DC-X





From Wikipedia: http://en.wikipedia.org/wiki/McDonnell_Douglas_DC-X

The future of the DC-X

Several engineers who worked on the DC-X have since been hired by Blue Origin, and their Blue Origin New Shepard vehicle is based on the DC-X design. Blue Origin does not require the high cross range capabilities, and therefore uses a base-first re-entry profile. Also, the DC-X provided inspiration for many elements of Armadillo Aerospace's, Masten Space Systems's, and TGV Rockets's spacecraft designs.

Returning the DC-X design to NASA's active research portfolio has been considered for some time now. Some NASA engineers believe that the DC-X could provide a solution for a manned Mars lander. Had a DC-type craft been developed that operated as an SSTO in Earth's gravity well, even if with only a minimum 4-6 crew capacity, variants of it might prove extremely capable for both Mars and Moon missions. Such a variant's basic operation would have to be "reversed"; from taking off and then landing, to landing first then taking off. Yet, if this could be accomplished on Earth, the weaker gravity found at both Mars and the Moon would make for dramatically greater payload capabilities, particularly at the latter destination.

Some proposed design changes include using an oxidizer/fuel combination that doesn't require the relatively extensive ground support required for the liquid hydrogen and liquid oxygen that DC-X utilized, and adding a fifth leg for increased stability during and after landing. Recently, NASA's Centennial Challenges program has announced a suborbital Lunar Lander Challenge which is a prize for the first team to build a VTVL rocket that has the same delta-v as a vehicle capable of landing on the moon and operate it under competition conditions.

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Here is an interesting snippet:

The first flight on 18 May 1996 resulted in a minor fire when the deliberate "slow landing" resulted in overheating of the aeroshell. The damage was quickly repaired and the vehicle flew two more times on 7 and 8 June, a 26-hour turnaround. On the second of these flights the vehicle set its altitude and duration records, 3140 meters and 142 seconds of flight time. Its next flight, on 7 July, proved to be its last. During testing, one of the LOX tanks had been cracked. When a landing strut failed to extend due to a disconnected hydraulic line, the DC-XA fell over and the tank leaked. Normally the structural damage from such a fall would constitute only a setback, but the LOX from the leaking tank fed a fire which severely burned the DC-XA, completely destroying it.

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For the Record: I worked for Rockwell at the time, who also proposed a SSTO vehicle known as 'X-33' ... It was based more or less on the existing space shuttle, and was rather conservative in that regard .... It lost out to the more exotic Lockheed VentureStar, which itself proved to be an unworkable design that never made it passed the 1/5 scale model stage after the composite fuel tank ruptured ... There was no feasible redesign possible .... It was cancelled as well ...

As it turned out, the 'conventional' Rockwell X-33 was the most viable option ....