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Japan Successfully Launches Solid Fuel Rocket (oann.com)
randomErr writes: Japan successfully launched a solid fuel rocket named Epsilon-2. The 26-meter-long rocket launched from the Uchinoura Space Center at about 8 p.m. local time. Japan Aerospace Exploration Agency (JAXA) said this is the latest in Tokyo's effort to stay competitive in an industry that has robust growth potential and strong security implications. Also, this is to curb costs for rocket launches. The Epsilon-2 three-stage rocket [is part of a new generation of solid propellant rockets that aim] to put communication and weather satellites in space.
https://www.nasaspaceflight.co...
This is news for nerds. Any "nerd" who doesn't think rocketry is awesome should probably turn in their badge on the way out.
Usually you have to fill liquid fuelled ones up just before you launch them. This means if anyone is observing you, they know in advance that you're going to launch.
This can be a disadvantage for certain applic@.m,mk
no carrier
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Solid rocket motors have tradeoffs. In some circumstances, they make sense.
They are long-term storage-stable. Build it, stick it in a silo somewhere, and leave it be for a few years, it will still launch just fine. Hypergolic liquid-fueled rockets can't be kept ready-to-launch for more than a few days*, and cryogenic liquid-fueled rockets can't be kept ready-to-launch for more than a few hours. This makes them particularly preferable for military uses, everything from little anti-tank rockets to ICBMs. This also reduces the number of ground crew needed - you don't need to worry about fueling, just electricals and signals.
They have extremely high levels of thrust, due to the extremely high energy density. The Shuttle's SRBs were each twice as powerful as the largest liquid-fueled rockets. This makes them very popular as boosters.
They have a lot of impulse per unit volume. What most rockets care about is impulse per unit mass (aka specific impulse), but some cases care about volume. If you're launching from an aircraft, like Stratolaunch or Pegasus, this matters. If you have constrained volume because you're in a fixed-size fairing, this matters. If you're launching from a submarine, this matters.
It's also often a matter of economies of scale. Countries with military missile programs (which have many reasons to go solid-fueled) often use them for other things as well, either to subsidize their military-industrial complex or to take advantage of existing scale to make civilian rocketry cheaper, depending on how cynical you are. The US, masters of solid-fueled ICBMs, used a pair of massive SRBs on the Space Shuttle, and will use them again on SLS, if that ever flies. The ESA's Ariane 5 uses SRBs based on a French SLBM. Japan may not field ICBMs, but they too have a reason - the first stage of this rocket is almost identical to the booster of their H-II rocket.
The higher stages are solid-fueled presumably to maintain that low-ground-crew capability, and the minor reduction in drag can't hurt either.