Taking a look at the existing spaces & load bearing structures in a rocket design and then going with 6 legs is plausible. Walking rockets, not so much.Rapid reuse is not required to reduce launch costs. Cheap reuse is. If a stage needs to spend x days or even weeks in transfer that should not be that expensive in itself, you "just" need more hardware in rotation.That said a leg design that can be retracted at will goes a long way to make recovery and refurbish operations simpler and faster.What I find more interesting is the small footprint of the deployed legs (~1.8x tank diameter) compared to the F9 (~5.6x ?), even smaller(!) than NS (~2x). Blue must be very certain that they can land the stage perpendicular, with very small tipping moments. Given the offshore recovery plans downrange that makes me think less barge and more Sea Launch style platform. (Land on a platform, transfer on a ship with platform cranes, unload at launch site, repeat.)
Some math: R=L cos (180/n)where R=tipover radius, L=leg length, n=# of legs.
After arrival at the Integration Facility, the 1st Stage and 2nd Stage, and a possible 3rd Stage, would then be mated together and integrated onto the Transporter Erector system. Following integration of the booster stages, the SV (or PA) would be attached, and then the entire system would undergo a readiness test. The OLV would then be transported from the Integration Facility to the Launch Pad and erected for launch. After a successful launch the first stage would return to the Earth for recovery in the Atlantic Ocean approximately 750 nautical miles downrange in the Atlantic Ocean, east of and well off the Carolina coast, and any payload or capsule would land under parachute at a yet to be determined land site in Texas.
Quote from: leaflion on 10/19/2016 03:34 amSome math: R=L cos (180/n)where R=tipover radius, L=leg length, n=# of legs.Some calculations below.n R/L3 0.54 0.7075 0.8096 0.8667 0.9018 0.924My personal preference is five legs. That's the minimum number where you can have one leg fail and still be standing. Here's the probably of falling given probably of a leg failure is p = 1% = 0.01. With five legs there are five combinations of single leg and five combinations of dual leg failures that are survivable. Compared to four legs, we can reduce the failure rate from about 1 in 20 to about 1 in 2020. Six legs only goes down to 1 in 3250.n Pf p=0.013 1-(1-p)^3 = 2.97%4 1-(1-p)^4 = 4.94%5 1-(1-p)^5 - 5p(1-p)^4 - 5p^2(1-p)^3 = 0.0495%6 1-(1-p)^6 - 6p(1-p)^5 - 12p^2(1-p)^4 = 0.0308%