[off topic]: IRL decoupler

[crunch]

i'm trying to do a report assessment on space craft and one the things i'm talking about is decouplers. the point is the only information i can fined is about the decouplers in KSP e.g. ( http://wiki.kerbalspaceprogram.com/wiki/Decoupler_and_separator ). if anyone knows where i can fined some info on the IRL decouplers, that would be really helpful.

[SkyRender]

That's because "decoupler" is not the correct term for those devices. The correct term is "pyrotechnic fastener".

[RainDreamer]

You should try asking in the science lab forums instead of general discussion. Lots of scientifically-minded people there with a wealth of knowledge about this stuff.

[Luis]

As Skyrender suggests, real rockets don't normally have a discrete ring-shaped device called a decoupler. Stage separation uses a series of charges and electronics that are integrated with the top of the stage. My copy of the Saturn V Flight Manual (Snowball Publishing) says this:

"Ordnance for first plane separation consists of two exploding bridgewire (EBW) firing units, two EBW detonators, and one linear shaped charge (LSC) assembly, which includes the LSC (containing 25 grains per foot of RDX) with a detonator block on each end. The EBW firing units are installed on the S-IC/S-II interstage slightly below the S-II first separation plane. The leads of the EBW firing units are attached to the EBW detonators which are installed in the detonator blocks of the LSC assembly. The LSC detonator blocks are installed on adjustable mounts to provide for length variations of the LSC assembly and the circumferance tolerances of the interstage. The LSC is routed from the detonator blocks around the periphery of the interstage. The LSC is held in place by retaining clips and encased by covers which are secured by clips and sealed to environmentally protect the LSC."

KSP just lumps all this together into a single component called a decoupler, for convenience.

[Nibb31]

Yes, real rockets typically use explosive bolts, because they are the less failure-prone method of separating two parts that were previously meant to be firmy attached. Pyros are also used for aircraft ejection seats and cockpit canopies and hatches.

Even with explosive bolts, there have been failures. A couple of Soyuz missions have had some hairy re-entrys because 1 or 2 explosive bolts failed to fire, causing the service module to stay attached until the attachment points were ripped off by the aerodynamic load.

SpaceX tends to use mechanical latches instead of pyros for obvious reusability reasons.

[Camacha]

Though you would have to independently confirm this, I am pretty sure I saw a vehicle with a screw and spring arrangement too. Large screws/threads kept the parts together, until they were unscrewed via motor and compressed springs pushed the parts apart.

Edit: I have found this, though this is off of a micro satellite. I think I saw them used on bigger craft too.

[magnemoe]

Yes, real rockets typically use explosive bolts, because they are the less failure-prone method of separating two parts that were previously meant to be firmy attached. Pyros are also used for aircraft ejection seats and cockpit canopies and hatches.

Even with explosive bolts, there have been failures. A couple of Soyuz missions have had some hairy re-entrys because 1 or 2 explosive bolts failed to fire, causing the service module to stay attached until the attachment points were ripped off by the aerodynamic load.

SpaceX tends to use mechanical latches instead of pyros for obvious reusability reasons.

You can reuse everything except the explosive bolts anyway, bombs and other heavy stuff are often mounted with explosive bolts on fighter planes, friend of mine had some used bolt ends.

However they might not want to use them inside the interchange faring then they want to reuse the lower stage and don't damage the upper.

Benefit of explosive bolts is that they can handle heavy load, they are hollow pipes of wanted diameter, and they can not jam no matter how much bend or vibration you have.

[GigaG]

Doesn't Falcon 9 use clamps instead of explosive bolts?

[Nibb31]

Doesn't Falcon 9 use clamps instead of explosive bolts?

Not sure about the trunk or upper stage separation events, but the first stage does.