Begin by increasing accuracy for current F9 RTLS. Paint four small boxes on the landing pad and try to bullseye the leg tips. Explore enchancements to the landing radar + software, rinse, repeat. A low-cost way to start. If successful, graduate to four receptacles for the leg tips. Then, maybe, consider a portable on-pad cradle, at which point you build a core with fins/cradle guides instead of legs.
Quote from: Robotbeat on 01/24/2017 02:36 pmMasten Space Systems achieved the required accuracy as part of the lunar lander challenge. It's possible SpaceX may have to forgo hover slamming in order to get accurate enough, so the system has time to null all the rates. For the first flights, at least. The bad part of that isn't so much the performance loss as the wear and tear of hovering a rocket right about the cradle mechanism.Full throttlable control so that you can take some time to set down gently is essential. The F9 style hover slam is not going to get it there.Edit: spelling
Masten Space Systems achieved the required accuracy as part of the lunar lander challenge. It's possible SpaceX may have to forgo hover slamming in order to get accurate enough, so the system has time to null all the rates. For the first flights, at least. The bad part of that isn't so much the performance loss as the wear and tear of hovering a rocket right about the cradle mechanism.
Quote from: wannamoonbase on 01/24/2017 02:48 pmQuote from: Robotbeat on 01/24/2017 02:36 pmMasten Space Systems achieved the required accuracy as part of the lunar lander challenge. It's possible SpaceX may have to forgo hover slamming in order to get accurate enough, so the system has time to null all the rates. For the first flights, at least. The bad part of that isn't so much the performance loss as the wear and tear of hovering a rocket right about the cradle mechanism.Full throttlable control so that you can take some time to set down gently is essential. The F9 style hover slam is not going to get it there.Edit: spellingIt may, eventually. But getting it to work at all is going to be more important at first. And honestly, I think F9 can actually hover, they just don't do it for every flight.
honestly, I think F9 can actually hover, they just don't do it for every flight.
As for integrated second stage /cargo hold - that's the only way you can achieve multiple-per-day launches.Separate payload/fairing integration works for one launch per week, tops. Any kind of rapid reuse must have a "payload bay mentality",which means the payload bay is part of the vehicle. (Whether tanker, cargo, or people)
Quote from: Robotbeat on 01/24/2017 03:03 pmQuote from: wannamoonbase on 01/24/2017 02:48 pmQuote from: Robotbeat on 01/24/2017 02:36 pmMasten Space Systems achieved the required accuracy as part of the lunar lander challenge. It's possible SpaceX may have to forgo hover slamming in order to get accurate enough, so the system has time to null all the rates. For the first flights, at least. The bad part of that isn't so much the performance loss as the wear and tear of hovering a rocket right about the cradle mechanism.Full throttlable control so that you can take some time to set down gently is essential. The F9 style hover slam is not going to get it there.Edit: spellingIt may, eventually. But getting it to work at all is going to be more important at first. And honestly, I think F9 can actually hover, they just don't do it for every flight."Hovering is for humans"If flight control computers could goose a bumper sticker, that'd be it.When you hover you just give winds and other unknowns more time to influence your position.The best way to increase X-y accuracy is to hit the pad at higher velocity. Less time for unknown forces to act and unlike a human, a computer doesn't need to hover nearby to estimate the IIP.The only problem is that a you try to hit the pad at higher decelerations, you increase your Z uncertainty.The remedy for this is increase Z travel on capture. Which means a heavier mechanism.This is the gain of the cradle - you don't have to carry the landing gear with you, you leave it on the ground. Make it as tall and heavy as you want, to absorb as much residual vertical velocity as you need.My bet is that we'll see more slam, and less hover, but that because of the increased physical size, it'll look about the same.----As for integrated second stage /cargo hold - that's the only way you can achieve multiple-per-day launches.Separate payload/fairing integration works for one launch per week, tops. Any kind of rapid reuse must have a "payload bay mentality",which means the payload bay is part of the vehicle. (Whether tanker, cargo, or people)
Cradle and hold downs are feasibly exclusive
Quote from: Robotbeat on 01/24/2017 02:36 pmMasten Space Systems achieved the required accuracy as part of the lunar lander challenge. It's possible SpaceX may have to forgo hover slamming in order to get accurate enough, so the system has time to null all the rates. For the first flights, at least. The bad part of that isn't so much the performance loss as the wear and tear of hovering a rocket right about the cradle mechanism.Full throttlable control so that you can take some time to set down gently is essential. The F9 style hover slam is not going to get it there.
Quote from: Jim on 01/24/2017 04:46 pmCradle and hold downs are feasibly exclusiveI only partied with Mechanical Engineers in college so I might be missing something but why? If there's a flame trench below the cradle, why can't the cradle have hold down pins that are driven home after the stage is in the cradle, and that are released in the normal way?
Quote from: Lar on 01/24/2017 04:50 pmQuote from: Jim on 01/24/2017 04:46 pmCradle and hold downs are feasibly exclusiveI only partied with Mechanical Engineers in college so I might be missing something but why? If there's a flame trench below the cradle, why can't the cradle have hold down pins that are driven home after the stage is in the cradle, and that are released in the normal way?There aren't pins. They are clamps and they have to hold a vehicle during static fire. Just the opposite catching a vehicle during hoverslam.
Quote from: raketa on 01/23/2017 05:54 pmTheir landing is accurate, that I have no doubt, that will start to test their cradle technology.Based on what? Current accuracy is not enough for a cradle.
Their landing is accurate, that I have no doubt, that will start to test their cradle technology.
The cradle will do doubt be a GSE nightmare. But if you can solve it....
Quote from: Robotbeat on 01/24/2017 05:18 pmThe cradle will do doubt be a GSE nightmare. But if you can solve it....Maybe something like this.
The catch mechanism is gonna be awesome.
Quote from: IainMcClatchie on 01/25/2017 08:44 amThe catch mechanism is gonna be awesome. Yes, fantasy items always are