Moving this over from the L2 thread but in an edited format:Using the excellent FlightClub simulation, you can obtain propellant mass and acceleration at the point of booster seperation of T+142https://www.flightclub.io/results/?id=f18e450d-6562-4a57-ab0b-334977993d3a&code=FHD1I did the rough math in the L2 thread, but based off a sim that is stored there, the Flight Club sim is slightly different and means my old numbers aren't exact. Approximately though, it would have the center core throttle to about 70%, and the boosters shutting off all but 3 engines which are throttled to 70%. So, theoretically with the boosters matching core acceleration and being "unweighted" the top end of the boosters could push off pivoting about the lower attachment point, before gimballing inward towards the core while releasing to rotate the aft end of the booster away from the core while the core simultaneously throttles up to get away.Or that's all crazy and would never work, IDK not a rocket scientist.
The loads would be less than flight loads at the bottom connection point. Side boosters can throttle to where they are just matching core acceleration, so the loading during the pivot shouldn't be high at all. No other boosters have the thottle range present in 1-9 merlins
Quote from: GWH on 07/03/2017 04:47 amThe loads would be less than flight loads at the bottom connection point. Side boosters can throttle to where they are just matching core acceleration, so the loading during the pivot shouldn't be high at all. No other boosters have the thottle range present in 1-9 merlinsThis method is just so different than what anyone else does that it seems very risky. Getting those engines to stay plenty clear of each other at separation seems like a tall order without separation motors.
Didn't the shuttle SRB's have some residual thurst at separation that sent them to higher trajectories?
I wouldn't use the renderings to try and analyze this.
Quote from: GWH on 07/03/2017 05:13 amI wouldn't use the renderings to try and analyze this.We don't have much else. That's why I'm so curious about the separation method. It seems like a significant engineering task.
Quote from: yokem55 on 07/03/2017 06:40 amDidn't the shuttle SRB's have some residual thurst at separation that sent them to higher trajectories?IDK what the thrust was, but obviously you want to jettison while T/W is still slightly >1, otherwise they are a drag on the core. After jettison, T/W drops to <1, but even then, any thrust is partly offsetting gravity losses, therefore, yes, their thrust does still affect their trajectory to some small degree.
I would design the connection so that it detaches boosters and give them slight outward nudge on the nose, without any active mechanisms, when booster acceleration falls below core accel (and stays below - of course, the design needs to be resistant to vibration). IIRC R7 boosters do this.
Quote from: GWH on 07/03/2017 05:13 amI wouldn't use the renderings to try and analyze this.We do not have anything better (until we see actual FH photos), so...
Quote from: Mader Levap on 07/03/2017 06:33 pmQuote from: GWH on 07/03/2017 05:13 amI wouldn't use the renderings to try and analyze this.We do not have anything better (until we see actual FH photos), so...We do have pictures of actual Falcon Heavy boosters on the test stand at Mcgregor.Matthew