The latest was 0.7 meters off-center from the platform.This is quite good but might not be enought for the cradle landing.
Probably 2m or so
Is there any compilation of F9 landing precision statistics?The latest was 0.7 meters off-center from the platform.This is quite good but might not be enought for the cradle landing.What about earlier ones?Has the accuracy been about the same with some random variation, or been improving?(and has it always been off-center to same direction or to random direction?)I wonder if thy are constantly tweaking their landing control algorithms(so that they can in the future get it to the precision required by the cradle), or have they decided that the current algorithm is accurate enough for F9 and don't want to risk introducing some bug by changing it?
Continuing the trend of landing on the aft half.
There was a plot recently from the landing bingo game that showed the winning location for each landing. (BTW did I miss landing bingo for these last two launches?) it showed there was a consistent drift direction that we suspected was wind related. It is probably possible to calculate the distance from center for each one and plot over time to determine how landing accuracy has changed over time. Can anyone find that plot to post into this thread? I'm on my phone only and searching abilities are limited.
Quote from: cppetrie on 08/25/2017 02:28 pmThere was a plot recently from the landing bingo game that showed the winning location for each landing. (BTW did I miss landing bingo for these last two launches?) it showed there was a consistent drift direction that we suspected was wind related. It is probably possible to calculate the distance from center for each one and plot over time to determine how landing accuracy has changed over time. Can anyone find that plot to post into this thread? I'm on my phone only and searching abilities are limited.Data for landings on the barge shouldn't be included since there are errors in the location of the barge. Only data on ground based landings should be looked at.
The cradle itseft might move to match the stage. I've seen a 400mT crane in an well intervention ship (oil & gas) moving sideways and up/down by 2.5 meters to each side, to account for sea motion.
Quote from: IRobot on 08/25/2017 08:32 amThe cradle itseft might move to match the stage. I've seen a 400mT crane in an well intervention ship (oil & gas) moving sideways and up/down by 2.5 meters to each side, to account for sea motion.It doesn't even have to move... If the cradle has some sort of vanes/glove that can shift the landing vehicle to its final resting position. Building something like this that can handle a 2m horizontal error is certainly possible. And more likely than a dynamic moving system, IMO.Think of the landing cradle as the equivalent of the passive cone in a probe & drogue docking system. (see image)
Quote from: Lars-J on 08/25/2017 05:58 pmQuote from: IRobot on 08/25/2017 08:32 amThe cradle itseft might move to match the stage. I've seen a 400mT crane in an well intervention ship (oil & gas) moving sideways and up/down by 2.5 meters to each side, to account for sea motion.It doesn't even have to move... If the cradle has some sort of vanes/glove that can shift the landing vehicle to its final resting position. Building something like this that can handle a 2m horizontal error is certainly possible. And more likely than a dynamic moving system, IMO.Think of the landing cradle as the equivalent of the passive cone in a probe & drogue docking system. (see image)Seems to me that tis would require some large, robust (heavy) surfaces on the returning booster. The equipment on the ground can be arbitrarily robust, the modifications to the booster have to be significantly lighter than landing gear for the effort to pay off.Matthew
I think they need a lot more return to launch site and see how accurate they can get before using a landing cradle.
Is there any compilation of F9 landing precision statistics?The latest was 0.7 meters off-center from the platform.This is quite good but might not be enought for the cradle landing.
I agree with Jim. The ship is moving or trying to stay in one position in a moving sea. It is usually more windy at sea also. The landing pad(s) are fixed and never move. It is all up to the rocket to hit the center on land. I think they need a lot more return to launch site and see how accurate they can get before using a landing cradle. Maybe the could land on a movable landing cradle, that can land it away from the launch pad. The cradle could then carry the rocket over the launch pad for refueling and launching. Then having a spare movable cradle in case of crash so as not to keep other rockets from launching and landing. Something like the mobile platform for Saturn V, shuttle, and SLS, but either on tracks for a traditional locomotive to move or wheels.
Quote from: hkultala on 08/25/2017 06:51 amIs there any compilation of F9 landing precision statistics?The latest was 0.7 meters off-center from the platform.This is quite good but might not be enought for the cradle landing.If they can routinely get 0.7 meters, or even close, it's plenty good enough for landing two boosters on one ship. That would result in a big boost in FH payload, at the cost of two ships in one ocean (one to catch the outside boosters, and one further downrange to catch the central core).
Quote from: LouScheffer on 08/26/2017 01:50 pmIf they can routinely get 0.7 meters, or even close, it's plenty good enough for landing two boosters on one ship. That would result in a big boost in FH payload, at the cost of two ships in one ocean (one to catch the outside boosters, and one further downrange to catch the central core).Might want to build the second ship to be larger.What would happen to boosters that close together? If one was landed briefly before the other. What would the affects of the second landing (engine exhaust) be on the first?
If they can routinely get 0.7 meters, or even close, it's plenty good enough for landing two boosters on one ship. That would result in a big boost in FH payload, at the cost of two ships in one ocean (one to catch the outside boosters, and one further downrange to catch the central core).