Crazy question: could you help the boosters separate by spinning the rocket along the axis of flight?
Quote from: Eerie on 07/03/2017 06:56 pmCrazy question: could you help the boosters separate by spinning the rocket along the axis of flight?Oh you mean like an aircraft roll? I guess it is theoretically possible, but it seems risky. I expect the separation to be done using a combination pushers (like stage separation) followed by nitrogen thrusters to assure separation. Some have speculated that the center engine of the boosters will keep firing to provide additional control.
Quote from: Lars-J on 07/03/2017 07:03 pmQuote from: Eerie on 07/03/2017 06:56 pmCrazy question: could you help the boosters separate by spinning the rocket along the axis of flight?Oh you mean like an aircraft roll? I guess it is theoretically possible, but it seems risky. I expect the separation to be done using a combination pushers (like stage separation) followed by nitrogen thrusters to assure separation. Some have speculated that the center engine of the boosters will keep firing to provide additional control.I do this often in KSP if I have recontact issues during sep. Induce stable roll, stage, then allow the boosters to spin away, then de-roll. Works like a charm
Quote from: TomH on 07/03/2017 06:58 amQuote 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.No, the SRB's were jettison when they could no longer carry their own weight. That is why they drop away
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.
Didn't the shuttle SRB's have some residual thurst at separation that sent them to higher trajectories?
Why are people coming up with all these Heath Robinson separation schemes when the booster CBCs on Delta IV have a perfectly sensible system? Boosters burn out, Booster Separation Rocket Motors (BSRM), located near the nose, fire, boosters tumble away from core. What do they Falcon Heavy boosters have conveniently located near the nose? Ah some, N2 thrusters which we know can flip a stage around in no time.....
For the same reason that SpaceX uses spring or some other inert pushers to separate S1 and S2 instead of explosive bolts or rocket motors. They also have grid fins conveniently located near the nose
Because there aren't any N2 thrusters at the base of the rocket, so the booster wouldn't be capable of lateral movement only rotational. Rotating both boosters about their center of gravity only would cause the tails to colide in the absence of any lateral movement. ...
Quote from: jak Kennedy on 07/04/2017 01:25 pmFor the same reason that SpaceX uses spring or some other inert pushers to separate S1 and S2 instead of explosive bolts or rocket motors. They also have grid fins conveniently located near the nose Where in using the N2 thrusters are explosive bolts or rocket motors involved? Also, how are you planning on unfolding the grid fins while the boosters are still attached? They take several second to unfold after all, and you'd need their control authority immediately following booster staging. Also, at what altitude is booster staging? Is there even enough atmosphere left for the grid fins to have any control authority? That I very much doubt that
Quote from: GWH on 07/04/2017 01:17 pmBecause there aren't any N2 thrusters at the base of the rocket, so the booster wouldn't be capable of lateral movement only rotational. Rotating both boosters about their center of gravity only would cause the tails to colide in the absence of any lateral movement. ...This is why they have two pusher mechanisms for each side booster octaweb. They detach and pivot the forward ends away using the N2 ACS, then they detach and push away the octawebs with the two outside octaweb connections (see Lars-J's helpful drawing).
Quote from: old_sellsword on 07/04/2017 01:52 pmQuote from: GWH on 07/04/2017 01:17 pmBecause there aren't any N2 thrusters at the base of the rocket, so the booster wouldn't be capable of lateral movement only rotational. Rotating both boosters about their center of gravity only would cause the tails to colide in the absence of any lateral movement. ...This is why they have two pusher mechanisms for each side booster octaweb. They detach and pivot the forward ends away using the N2 ACS, then they detach and push away the octawebs with the two outside octaweb connections (see Lars-J's helpful drawing).Yeah those two struts at the bottom of the wind tunnel model could definitely have a pusher component to them, Would simplify the whole arrangement a lot. Do you know this for fact or are you speculating?