Posted on 08/02/2005 8:56:13 AM PDT by jbstrick
> An exploding liquid booster cannot be "shut down."
Agreed, but it's also not likely generating much thrust,
which allows the escape tower to function.
If you're riding a solid, and range safety detects a
failing O-ring, you may not be able to uncouple until
the tube ruptures and/or the stack veers out of control.
Like I said, I'd like to see the scenarios.
Along with...I dunno...large tungsten rods?
That's probably true. There would be some failure modes that would be difficult. John Glenn's escape rocket would have provided thrust in excess of what would be needed as a minimum to get away from the Atlas under full thrust. Apparently the escape tower had quite a kick. Lots of gee force.
> a capsule with a parasail lacks the cross-range capability of a true lifting body design
Actually, the Apollo capsule *did* have an impressive cross-range. Remember, it did not drop straight in, blunt end directly forward; it was asymmetrically balanced, so it "leaned" over to one side. That turned it into a half-ass decent lifting body with several hundred miles cross range. Hypersonic L/D was surprisingly good.
Only the second and third stages of the Saturn stack could be powered down. When the S-1 was lit, you were committed to see it through. The Atlas booster used for Mercury also had no shut-off switch.
The range safety officer would push the red button immediately, pop the forward pressure port, and thrust would end nearly instantly. There could also be a red button aboard the ship.
Yes, it should, but a snail-like pace is already built into the timeline.
> It wasn't easy to get it to burn and it burned hard--took a good roaring wood fire.
Modern solid rocket propellants don't burn well at low pressures. When the Shuttle RSRM is fired on the static pad, there's always a goodly amount of propellant left over... propellant that was snuffed out when the pressure got too low at burnout. I can explain the physics, but it's boring.
> If you're riding a solid, and range safety detects a
failing O-ring...
You ride all the way to orbit. The Challenger failure, if it were to be applied to "The Stick" CEV-launcher, would have resulted in a successful orbital flight. Remember... after the ET and the Challenger were reduced to confetti by aerodynamic forces...the two SRBs had to be intentionally destryoed by explosive charges on ground command. Shuttle SRB's are *tough*.
The Apollo capsule has a flattish, broad base. It can glide fairly far in a chosen direction. Even so, it landed a couple hundred miles from where they hoped it would at least once. They need a large open space to land, and they chose a water landing in the open sea. Soyuz and the Chinese divine craft land on the hard earth, and sometimes land hard and nowhere near where they hoped.
Your explanation has TMA* that WDU**. Could you UPE** please?
*Too Many Acronyms
**We Don't Understand
***Use Plain English
Okay, I'll STFU.
And that won't happen with a liquid fueled booster?
#4 — The SRBs (Solid Rocket Boosters) cannot be shut down, does that make it less safe than using liquid rocket engines? This is a very commonly asked question. In reality, once the vehicle is launched, the last thing the astronaut crew would want to do is shut down the main engines. The most reliable liquid rocket engine manufactured today is the Space Shuttle Main Engine (SSME), and the most reliable solid rocket motor is the SRB. Recent Probabilistic Risk Assessment (PRA) analysis for the Space Shuttle show that the contribution to risk during launch from the SRBs is an order of magnitude less than from the SSMEs. Also, shutting down a liquid rocket engine is not trivial. An important parameter used to look at the effects of shutting down a liquid rocket engine, which is suffering a malfunction, is what is referred to as the "catastrophic failure ratio." This is defined as the percent of time that an engine will fail catastrophically. The accepted value for current rocket engines is 20-30%. The SSME and the J-2 are the only engines with in-flight shutdown capability in response to malfunctions. Even if the engine is designed to enable in-flight shutdown, there are failure modes that will be catastrophic for both liquid and solid rocket motor designs. The advantage of a solid rocket motor is that the chance of having a catastrophic failure is less likely. This is due to its simplicity relative to the liquid design. In the event of a catastrophic failure, a solid rocket motor actually provides more reaction time and better survivability for a launch escape system to protect the crew. Most catastrophic failures of a solid rocket motor actually result in a phenomenon referred to as thrust augmentation, which is easily detected by an In-Vehicle Health Monitoring System (IVHM), which can be used to signal the Launch Escape System.
That's only because of the fragility of the components riding atop the stack.
The new CEV and SRB vehicle apparently is designed not to need to throttle back for that.
Can the Pegasus get a payload to the ISS? Maybe the Pegasus could be used to re-fuel a space tug.
Holtz
JeffersonRepublic.com
> it landed a couple hundred miles from where they hoped it would at least once
Yes. Even though the Apollo capsule ahd a good cross range... it was a capability that I believe went unused. Imagine it as a lifting body that they just locked the control surfaces on, and just let it go where it was gonna go. Steering Apollo would have meant using the RCS jets and/or shifting CG in flight, and I believe they never did this in actual practice.
Reliability and Crew Safety Assessment for Solid Rocket Booster / J-2S Based Launch Vehicle
> Even if the engine is designed to
enable in-flight shutdown, there are failure modes that
will be catastrophic for both liquid and solid rocket motor
designs.
Which was the whole reason for the recent launch delay due to the sensor. If the SSME suddenly ran out of hydrogen without going through proper shutdown procedure... the turbopump would likely tear itself to bit, with effects similar to when that DC-10's engine tore itself to bits.
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