What causes pogo effect?

During the last ten seconds of that first stage burn, the rocket experienced longitudinal oscillations called “pogo effect.” Pogo occurred when a partial vacuum in the fuel and oxidizer feed lines reached the engine firing chamber causing the engine to skip.

What is Pogo on the Apollo?

Pogo oscillation is a self-excited vibration in liquid-propellant rocket engines caused by combustion instability. The name is a metaphor comparing the longitudinal vibration to the bouncing of a pogo stick. Pogo oscillation places stress on the frame of the vehicle, which in severe cases can be dangerous.

What happened on the day Apollo 6 launched?

Apollo 6 was intended to demonstrate the ability of the Saturn V’s third stage, the S-IVB, to propel itself and the Apollo spacecraft to lunar distances. Its components began arriving at the Kennedy Space Center in early 1967….Apollo 6.

Spacecraft properties
Period	389.3 minutes
Epoch	April 4, 1968
Apollo program Apollo 7 →

What went wrong with the first stage on Apollo six?

Two minutes into the flight, the first stage experienced about 30 seconds of vertical oscillations known as “pogo effect”, which caused no serious damage but would have been very uncomfortable for any crew. Then during the second stage burn, two of the five engines shut down prematurely.

What is thrust oscillation?

Also called “resonant burning,” thrust oscillation is a phenomenon in all solid propellant rockets forcing vibrations through the entire structure, in the case of Ares I, that includes the Orion crew module.

What is Pogo stability?

POGO is the longitudinal instability of liquid propellant launch vehicles due to the interaction of structural dynamics with the propulsion system. This interaction may give rise to the initiation of vibrations of large magnitudes when the propulsion and structural frequencies are nearer.

Did Apollo 7 fail?

Extensive testing of the CSM took place, and also the first live television broadcast from an American spacecraft. Despite tension between the crew and ground controllers, the mission was a complete technical success, giving NASA the confidence to send Apollo 8 into orbit around the Moon two months later.

Was there an Apollo 7?

Apollo 7 was the first crewed spaceflight of the Apollo program that went into space. The crew of Wally Schirra, Don Eisele and Walter Cunningham spent nearly 11 days in space as they orbited Earth and tested out the command module spacecraft that was designed to bring humans safely to the moon and back again.

What is a Pogo accumulator?

The 3-D printed part tested, called the pogo accumulator, is a beachball-sized piece of hardware that acts as a shock absorber by regulating liquid oxygen movement in the engine to prevent the vibrations that can destabilize a rocket’s flight.

Did the Apollo 8 Land on the Moon?

December 27, 1968
Apollo 8/Land dates

What causes a pogo oscillation in a rocket?

The most famous pogo oscillation was in the Saturn Vfirst stage, S-IC, caused by the cruciform thrust structure. This structure was an “X” of two I-beams, with an engine on the end of each beam and the center engine at the intersection of the beams.

What happened to the pogo effect on the Apollo 13 mission?

Apparently the issue could not be addressed in time for the Apollo 13 mission as is evidenced by this note in the NASA archives available online. During the Apollo 13 flight the pogo effect had reappeared, this time on the second stage. Severe oscillations had forced an early shutdown (two minutes ahead of schedule) of the inboard engine.

What was the cause of the pogo engine failure?

Pogo occurred when a partial vacuum in the fuel and oxidizer feed lines reached the engine firing chamber causing the engine to skip. These oscillations then travelled up the axis of the launch vehicle resulting in intense vibration in the Command Module and causing some superficial structural damage to…

What is Pogo and how does it occur?

The vehicle oscillations cause pressure oscillations in the propellant system, leading to an oscillating flow rate in the pumps that results in thrust oscillations from the engine that further excite the structure. A key factor in the occurrence of Pogo is how the pumps respond to pressure oscillations in the feed lines.

https://www.youtube.com/watch?v=f320m5x89MY