Count Until a Staff Member Posts! (394)

[Bricket]

19
Brisky, talking about rocket science

[Emtile]

20
Ha ha ha! Comedy.....

[Brisky]

21

I'm not the one talking, this is all straight from the can...

S-IC thrust comparisons
Apollo 17 ascent flight parameters

Because of its large size, attention is often[citation needed] focused on the S-IC thrust and how this compares to other large rockets. However, several factors make such comparisons more complex than first appears:

    Commonly referenced thrust numbers are a specification, not an actual measurement. Individual stages and engines may fall short or exceed the specification, sometimes significantly.
    The F-1 thrust specification was uprated beginning with Apollo 15 (SA-510) from 1,500,000 lbf (6,670 kN) to 1,520,000 lbf (6,770 kN), yielding 7,610,000 lbf (33,850 kN) for the S-IC stage. The higher thrust was achieved via a redesign of the injector orifices and a slightly higher propellant mass flow rate. However, comparing the specified number to the actual measured thrust of 7,800,000 lbf (34,800 kN) on Apollo 15 shows a significant difference.
    There is no way to directly measure thrust of a rocket in flight; Rather, a mathematical calculation is made from combustion chamber pressure, turbopump speed, calculated propellant density and flow rate, nozzle design, and atmospheric pressure.
    Thrust varies greatly with external pressure and thus with altitude, even for a non-throttled engine. For example, on Apollo 15, the calculated total liftoff thrust (based on actual measurements) was about 7,830,000 lbf (34,810 kN), which increased to 9,200,000 lbf (40,800 kN) at T+135 seconds, just before center engine cutoff (CECO), at which time the jet was heavily underexpanded.
    Thrust specifications are often given as vacuum thrust (for upper stages) or sea level thrust (for lower stages or boosters), sometimes without qualifying which one. This can lead to incorrect comparisons.
    Thrust specifications are often given as average thrust or peak thrust, sometimes without qualifying which one. Even for a non-throttled engine at a fixed altitude, thrust can often vary somewhat over the firing period due to several factors. These include intentional or unintentional mixture ratio changes, slight propellant density changes over the firing period, and variations in turbopump, nozzle and injector performance over the firing period.

Without knowing the exact measurement technique and mathematical method used to determine thrust for each different rocket, comparisons are often inexact. As the above shows, the specified thrust often differs significantly from actual flight thrust calculated from direct measurements. The thrust stated in various references is often not adequately qualified as to vacuum vs sea level, or peak vs average thrust.

Similarly, payload increases are often achieved in later missions independent of engine thrust. This is by weight reduction or trajectory reshaping.

The result is there is no single absolute figure for engine thrust, stage thrust or vehicle payload. There are specified values and actual flight values, and various ways of measuring and deriving those actual flight values.

The performance of each Saturn V launch was extensively analyzed and a Launch Evaluation Report produced for each mission, including a thrust/time graph for each vehicle stage on each mission.[40]

[Emtile]

22

Copy pasting?

[Brisky]

23

No, it's the spam I bought!

After the construction and ground testing of a stage was completed, it was then shipped to the Kennedy Space Center. The first two stages were so large that the only way to transport them was by barge. The S-IC, constructed in New Orleans, was transported down the Mississippi River to the Gulf of Mexico. After rounding Florida, it was then transported up the Intra-Coastal Waterway to the Vertical Assembly Building (now called the Vehicle Assembly Building). This was essentially the same route which would be used later by NASA to ship Space Shuttle External Tanks. The S-II was constructed in California and thus traveled to Florida via the Panama Canal. The third stage and Instrument Unit could be carried by the Aero Spacelines Pregnant Guppy and Super Guppy, but could also have been carried by barge if warranted.

On arrival at the Vertical Assembly Building, each stage was inspected in a horizontal position before being moved to a vertical position. NASA also constructed large spool-shaped structures that could be used in place of stages if a particular stage was late. These spools had the same height and mass and contained the same electrical connections as the actual stages.

NASA stacked or assembled the Saturn V on a Mobile Launcher Platform (MLP), which consisted of a Launch Umbilical Tower (LUT) with nine swing arms (including the crew access arm), a "hammerhead" crane, and a water suppression system which was activated prior to launch. After assembly was completed, the entire stack was moved from the VAB to the launch pad using the Crawler Transporter (CT). Built by the Marion Power Shovel company (and later used for transporting the smaller and lighter Space Shuttle), the CT ran on four double-tracked treads, each with 57 'shoes'. Each shoe weighed 2,000 pounds (910 kg). This transporter was also required to keep the rocket level as it traveled the 3 miles (4.8 km) to the launch site, especially at the 3 percent grade encountered at the launch pad. The CT also carried the Mobile Service Structure (MSS), which allowed technicians access to the rocket until eight hours before launch, when it was moved to the "halfway" point on the Crawlerway (the junction between the VAB and the two launch pads).

[Bricket]

24, sorry had to go for a bit

[Brisky]

25

The Saturn V carried all Apollo lunar missions. All Saturn V missions were launched from Launch Complex 39 at the John F. Kennedy Space Center in Florida. After the rocket cleared the launch tower, flight control transferred to Johnson Space Center's Mission Control in Houston, Texas.

An average mission used the rocket for a total of just 20 minutes. Although Apollo 6 experienced three engine failures,[41] and Apollo 13 one engine shutdown,[42] the onboard computers were able to compensate by burning the remaining engines longer to achieve parking orbit. None of the Saturn V launches resulted in a payload loss.
S-IC sequence
A condensation cloud surrounds the Apollo 11 Saturn V as it works its way through the dense lower atmosphere. See max Q.

The first stage burned for about 2 minutes and 41 seconds, lifting the rocket to an altitude of 42 miles (68 km) and a speed of 6,164 miles per hour (2,756 m/s) and burning 4,700,000 pounds (2,100,000 kg) of propellant.[43]

At 8.9 seconds before launch, the first stage ignition sequence started. The center engine ignited first, followed by opposing outboard pairs at 300-millisecond intervals to reduce the structural loads on the rocket. When thrust had been confirmed by the onboard computers, the rocket was "soft-released" in two stages: first, the hold-down arms released the rocket, and second, as the rocket began to accelerate upwards, it was slowed by tapered metal pins pulled through dies for half a second. Once the rocket had lifted off, it could not safely settle back down onto the pad if the engines failed. The astronauts considered this one of the tensest moments in riding the Saturn V, for if the rocket did fail to lift off after release they had a low chance of survival given the large amounts of propellant. A fully fueled Saturn V exploding on the pad would have released the energy equivalent of two kilotons of TNT. To improve safety, the Saturn Emergency Detection System (EDS) inhibited engine shutdown for the first 30 seconds of flight. (See Saturn V Instrument Unit)

It took about 12 seconds for the rocket to clear the tower. During this time, it yawed 1.25 degrees away from the tower to ensure adequate clearance despite adverse winds. (This yaw, although small, can be seen in launch photos taken from the east or west.) At an altitude of 430 feet (130 m) the rocket rolled to the correct flight azimuth and then gradually pitched down until 38 seconds after second stage ignition. This pitch program was set according to the prevailing winds during the launch month. The four outboard engines also tilted toward the outside so that in the event of a premature outboard engine shutdown the remaining engines would thrust through the rocket's center of mass. The Saturn V reached 400 feet per second (120 m/s) at over 1 mile (1,600 m) in altitude. Much of the early portion of the flight was spent gaining altitude, with the required velocity coming later. The Saturn V broke the sound barrier at just over 1 minute at an altitude of between 3 and 4 nautical miles. At this point, shock collars, or condensation clouds, could be seen forming around the bottom of the command module and around the top of the second stage.
Apollo 11 S-IC separation

At about 80 seconds, the rocket experienced maximum dynamic pressure (max Q). The dynamic pressure on a rocket varies with air density and the square of relative velocity. Although velocity continues to increase, air density decreases so quickly with altitude that dynamic pressure falls below max Q.

I think lot'sa people went...

[Bricket]

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We were so close, multiple time 

[Emtile]

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Yet we can do it again

[Bricket]

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yes indeed we can!

[Aveq]

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boop bepbep

[Bricket]

30
welcome back Aveq

[Brisky]

31

Ow, yeeeet!

Let's keep going!

[Bricket]

32
yes indeed!

[Emtile]

33

All aboard the noot train! Noot Noot!