What do you think of my "Hexapod Locomotive" conjecture?
Quote from: Stan-1967 on 10/18/2016 07:51 amWhat do you think of my "Hexapod Locomotive" conjecture?No way that is happening. The number of legs reduces the loads by each individual leg and hence the attach point structure on the vehicle.
Added mass to turn the landing gear into hexapod locomotion would reduce payload. Increasing complexity increases cost and reduces reliability.Best to keep the ground support equipment on the ground.
1) 6 means it can an be symmetrical with the 6 engines. Something else than 3 or 6 would mean much more complex mechanical structures.2)6 means there is redundancy. on the legs. One leg can fail totally and it's still stable. At least 5 legs needed for this, but 5 would be bad for symmetry. At least one F9 1st stage landing failed due failing leg, so the redundancy can be important.
Quote from: RonM on 10/18/2016 03:23 pmAdded mass to turn the landing gear into hexapod locomotion would reduce payload. Increasing complexity increases cost and reduces reliability.Best to keep the ground support equipment on the ground.You may be right, you may be wrong. There is no baseline of knowledge to weigh the advantages vs. disadvantages for this case. The few cases of reuse that have been attempted ( STS ) ended up being very expensive. Even F9 doesn't look too efficient in all the time, labor, & equipment needed to barge land, take the returned vehicle from vertical to horizontal, transport it & integrate a new payload. In this case, the advantage is enabling rapid reuse by quickly returning the rocket to the pad for another launch. Is it worth it? What does it cost vs. the alternatives?
Every addition of a features to a rocket that make it reusable ( legs, fins, multiple engines) is less mass efficient, & reduce the payload compared to an expendable vehicle, & increase complexity. The requirements for reuse then push the size of the rocket to be bigger & more costly. Your logic dismisses all of these options because they reduce payload, and yet multiple companies are out there pushing for reusable rockets. Why?
In the end, reuse is judged economically by adding up all the extra costs that amortize over N# launches against the cost of expendable. A walking hexapod rocket would be no different. You would tally all costs associated with adding more degrees of freedom into the mechanics of the legs, as well as any other ground equipment needed, and compare against the alternative. Finally, I see no requirement that all the hydraulics and power generator to articulate this hexapod concept be contained in the rocket. What is required is that each leg has enough degrees of freedom to articulate the CG within a tight range of motion. The mass intensive parts of a hydraulic system ( working fluid, pumps, generators) can be contained in mobile GSE.
1. Turning a rocket into a legged robot won't help with a barge landing. Like any other cargo, a crane is the best way to get the stage off of a barge.2. ...To make a rocket reusable you add what is necessary. Your lack of logic assumes it's a good idea to add unnecessary items to a rocket.3. Having to add the hydraulics and power after the rocket lands will take time, effort, and of course money. It would be easier and quicker to use a crane and transport vehicle.4. It's obvious that this idea would cost more than current landing operations.5. It might have some merit if the landing pad was on the Moon or Mars. There are no cheap cranes and transporters available off planet.
This is clearly an idea that Stan-1967 likes a lot, and nothing is going to change his mind.
Quote from: RonM on 10/18/2016 05:41 pm1. Turning a rocket into a legged robot won't help with a barge landing. Like any other cargo, a crane is the best way to get the stage off of a barge.2. ...To make a rocket reusable you add what is necessary. Your lack of logic assumes it's a good idea to add unnecessary items to a rocket.3. Having to add the hydraulics and power after the rocket lands will take time, effort, and of course money. It would be easier and quicker to use a crane and transport vehicle.4. It's obvious that this idea would cost more than current landing operations.5. It might have some merit if the landing pad was on the Moon or Mars. There are no cheap cranes and transporters available off planet.1. Has Blue said they will land New Glenn on a barge? RTLS? No they have not. Can New Glenn land and be stable on a small barge, or will it need to scale up to something much bigger and more expensive? You are assuming facts without evidence. Do you have inside information on SpaceX cost for barge, labor, storage, etc? 2. I am not assuming it is a good idea. I think it is possible to make it happen, but there is no basis either way to say if its better or worse without knowing specific costs.3. Again, you don't know any of this. It has taken over a week to get an F9 off a barge and back to horizontal storage. A walker articulating 1m/min could have the rocket back at the launchpad in less than a day if doing a a RTLS closeby. Everything takes time and money, so that fact is not a reason to do nothing. Do what is efficient.4. It is not obvious. What is your cost data that makes this obvious?
Maybe after landing the legs could be lifted one at a time and set down on wheeled bogeys? Then once all legs are up on wheels, a tug pulls it?
5. So you like the idea then!
1. Has Blue said they will land New Glenn on a barge? RTLS? No they have not.
Present plans call for returning first stages for a landing on a downrange ocean-going platform, and return it to a facility for reuse.[...]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: Stan-1967 on 10/18/2016 06:29 pm1. Has Blue said they will land New Glenn on a barge? RTLS? No they have not. Yes they have. To directly quote from Blue's planning application for the CCAFS pad;QuotePresent plans call for returning first stages for a landing on a downrange ocean-going platform, and return it to a facility for reuse.[...]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.
Dismissing ideas out of hand without any data, or pretending that optimal solutions to new problems (i.e reuse) are known, when they are clearly not, is boring and unimaginative.
Quote from: Stan-1967 on 10/18/2016 07:09 pmDismissing ideas out of hand without any data, or pretending that optimal solutions to new problems (i.e reuse) are known, when they are clearly not, is boring and unimaginative.Throwing stuff against the wall and seeing if it sticks is childish. Some basis thought has to be put into ideas. It is easy to dismiss ideas when they fail the eye test. This is a prime example of a solution looking for a problem.