On Monday, September 5, 2016 at 9:13:46 PM UTC+12, Fred J. McCall wrote:
William Mook wrote:

On Saturday, September 3, 2016 at 7:44:26 AM UTC+12, Fred J. McCall wrote:
William Mook wrote:

On Friday, September 2, 2016 at 2:19:19 AM UTC+12, Fred J. McCall wrote:
Rick Jones wrote:

Jeff Findley wrote:
The "violence" of a launch is largely a myth for liquid fueled
launch vehicles.

Myth or "history"? eg pogo/whatnot.


Pogo means the rocket has a problem. It's not a 'normal' liquid
rocket effect. The vibe environment from a solid is much, MUCH worse
than from a liquid.


Pogo oscillation is a self-excited vibration in liquid propellant rocket engines caused by combustion instability. The unstable combustion results in variations of engine thrust, causing variations of acceleration on the vehicle's flexible structure, which in turn cause variations in propellant pressure and flow rate, closing the self-excitation cycle. 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 potentially dangerous.


We all know what it is, Mookie. We don't need you plagiarizing Wiki
so you can try to sound like you know what you're talking about.

How I sound to others is of overweening importance to you emotionally isn't it? lol. What I reproduced here is accurate appropriate and informative. That is what you're saying, even though you constitutionally cannot bring yourself to say it in a way that isn't denigrating to me personally. Which says far more about you than it does about me.


No. The fact that you plagiarize sources fairly disgusting.




The nature of the pintle fed engine is such that Pogo oscillation does not occur.


Nobody anywhere promises that but you.

Promise? That's an interestingly inappropriate word choice. Facts are not promises. You obviously have not read and understood the pintle engine patents Grumman sued SpaceX over did you? I urge anyone to go and look at those, or this one;


You've made a statement you cannot support.

No, you've made a mistake and are blaming others instead of correcting your mistake.


https://www.google.ch/patents/US7827781


Note the use of the word "reduce" and not the word "eliminate".

Context friend. Context. The patent says in part, "improve rocket engine combustion stability and reduce harmonic disturbance within the engine chamber"

So, what is being reduced? Harmoinc disturbance. Now, WHY is that important?

to quote the patent yet again, "The longitudinal resonance is often multiplied by the effect of the variable backpressure created at the injector, and thus causes a varying flow rate through the injector. This leads to varying thrust from the engine known as the “pogo” effect."

which finally concludes with the word, "phased damping methods to eliminate multiple orders of combustion instability."

Got it?

So go **** yourself you blowhard knowitall.


snip MookMuck


--
"You take the lies out of him, and he'll shrink to the size of
your hat; you take the malice out of him, and he'll disappear."
-- Mark Twain