If you really want to get to the bottom of something form a committee. That way you will get to the bottom and still not have a proper solution.
This may get a bit complex but please bear with me.
According to the Rogers commission the Challenger was lost for the following reasons. First an “O” ring that sealed the circumferential area of two mating sections of the solid rocket booster engine was compromised by being exposed to very low temperatures. This allowed hot gasses and eventually a flame to escape from the damaged “O” ring. The flame impinged on the liquid oxygen tank and when it burned through the tank catastrophically exploded. That was the company line and that is what was told to the press and the world’s public.
Here is my theory and in order to explain it you the reader need an exposure to rocket science.
There are various types of solid motor the most prevalent is employed on small missiles such as those used on aircraft. These are what are called an end burn or cigarette burn propellant grain. The propellant grain burns like a cigarette and as the grain is consumed the internal pressure drops due to consumption of the grain and an increase in the internal volume. However, as the interior volume increases the consumption of the grain decreases the weight of the missile and the speed does not drop off until the grain is almost completely consumed.
On larger solid motors the grain is cast with a geometric shape in the center. It could be cruciform in shape or possibly star shape. If you were to measure the geometric shape by starting at one point and covering the distance around the grain until you reached the starting point the measurement would be equal to the internal circumference of the containing vessel. Because of the physical size of the Challenger Solid Rocket Motors (SRM) they had to be cast in sections with one section mated on top of another until the motor was fully assembled. To maintain a positive seal between the segments an “O” ring was installed. In this type of motor the burning takes place on the exposed surface of the geometric shape and as the grain is consumed the internal pressure remains the same and the thrust is stable.
One of the characteristics of a solid rocket motor is that the relationship of the burning surface has to remain constant within allowable parameters. If at ignition a large chunk were expelled from the motor nozzle the relationship would be disturbed resulting in combustion instability or even worse, explosion. The explosion would result from more propellant burning surface resulting in higher internal pressures. This could also be caused by a crack in the grain.
Now lets’ look at the Challenger report. The report stated that the flame front escaping from the damaged seal impinged on the tank. In just about every film I have seen the flame was pointing away from the tank. There may have been two flames but I have only seen one. Lets’ assume there was a flame that impinged on the tank and liquid Oxygen escaped and flowed into the flame. If you remember back in Jr. High science they taught about the fire triangle which stated that in order to have a fire you had to have fuel, Oxygen and a fire source. Where was the fuel that would result in such a violent explosion?
Now we get back to the flame that was escaping from the compromised “O” ring seal. In order to have a flame escaping it meant that the two mating surfaces of the adjacent segments had to be on fire otherwise, the flame could not get to the seal. Now go to the second paragraph above that deals with an increase of pressure. If the two adjacent surfaces were burning it could result in a significant increase in the internal pressure of the SRB resulting in a catastrophic rupture of the motor case. This would be analogous to a crack in the grain,
When you look at the pictures of the explosion you do not see any fire. What you do see is a white cloud made mainly of liquid Oxygen and possibly liquid Hydrogen. If the Oxygen and Hydrogen combined and ignited you would not see any flame but there might be some frozen condensation resulting from any combustion.
The question is, what do you think?
I shall now retire to paint a bull’s eye on my chest.
