The way landing burns work right now is the rocket calculates what speed it should be traveling at based on it's altitude mass and the pre-selected thrust level.
If you set it to do a 60% thrust landing, it will calculate how long it will take to slow down at 60% thrust and then another function will use that time to calculate what speed it should be traveling at the current altitued. Once the calculated speed is aproching the current actuall speed of the booster, engine ignites and a PID loop is setting the thrust to try and match the calculated speed.
While this approach works, the landings are a bit hard because if you do a 90% thrust landing, the booster will be touching down at a Thrust To Weight ratio of over 3. Not even mentioning three engine landings.
The solution to this is to split the landing burn into two parts. The first part will essentially work the same way as it does now. But then for the final touchdown a different method will be used to make sure that the landings are equally smoth no matter what kind of landing it is.
This should also make three engine landings possible as the three engines will only be used in the first phase, and then for the touchdown pahse, two outer engines will be shutdown and only the centre one will be used.
The way landing burns work right now is the rocket calculates what speed it should be traveling at based on it's altitude mass and the pre-selected thrust level.
If you set it to do a 60% thrust landing, it will calculate how long it will take to slow down at 60% thrust and then another function will use that time to calculate what speed it should be traveling at the current altitued. Once the calculated speed is aproching the current actuall speed of the booster, engine ignites and a PID loop is setting the thrust to try and match the calculated speed.
While this approach works, the landings are a bit hard because if you do a 90% thrust landing, the booster will be touching down at a Thrust To Weight ratio of over 3. Not even mentioning three engine landings.
The solution to this is to split the landing burn into two parts. The first part will essentially work the same way as it does now. But then for the final touchdown a different method will be used to make sure that the landings are equally smoth no matter what kind of landing it is.
This should also make three engine landings possible as the three engines will only be used in the first phase, and then for the touchdown pahse, two outer engines will be shutdown and only the centre one will be used.