I actually always wanted to be a pilot but my vision is terrible. I never worked as an aircraft engineer but was always very interested in planes. Obviously nobody would release information that shows how much explosives are needed and where but here is why I think small explosives are so dangerous:
-An aircraft that flies to high altitude is basically a large cylindrical pressure vessel with comparatively very thin walls. The skin is 1-2mm, about as thick as a dime or quarter. The maximum pressure differential in flight is less than 10psi and airframes are typically pressure tested to only 150% of the maximum expected in flight. I don't know what the burst strength is but it cannot be much higher than 20psi for commercial airliners. Planes are designed to handle normal operating stresses and pressures at the lowest weight possible, not bombs. There is not much safety factor or overdesign in aircraft since weight is so crucial. I’m sure you know that an airframe can be overstressed just by flying too aggressively.
-A bomb creates a local high pressure zone around it several times higher than 20psi. The velocity of the explosion is almost 30,000fps. At cruising altitude, the walls are already loaded and a high explosive placed at the exterior wall is guaranteed to punch through with some degree. A jagged hole at cruising speed can quickly begin to tear and disintegrate the plane. How big of a hole and how damaging it will be depends on many factors. It can also punch through the floor and spark the center fuel tank. I didn't say a tiny charge absolutely will take down a plane. I'm saying it can.
We already have seen a few incidents that prove how damaging explosives are:
-The Lockerbie bomb was only 300 grams of mainly RDX. That is about 200cc, the volume of a small 6.7oz cup of water. It is believed that the bomb was concealed inside a walkman tape player. However, the bomb was randomly placed in the cargo hold inside a suitcase and not at the wall. RDX produces incredible pressure up close but has a smaller blast radius than some other explosives. This was also a 747 and large planes have more room for expansion. Even so, the bomb instantly blew multiple holes in the side of the cargo hold, the bulkhead, the floor and the roof of the 747. The plane disintegrated seconds after. A bomb of this size can be fairly easily hidden INSIDE someones body. No gropers or scanners will see it.
- Ramzi Yousef placed a small liquid bomb on a Philippine Airlines 747. The exact quantity was not calculated like in Lockerbie but he claimed that it was only 1/10 of a bottle of contact lens cleaner. This is only 1 to 1.5oz and judging by how much less damage there was compared to Lockerbie, this is an accurate estimate. It was placed under a seat away from the exterior and closer to the center of the plane because his intent was to hit the center fuel tank. It blew a man-sized hole in the floor, cut the control cables in the ceiling and completely blew off the lower half of the man sitting there. The plane did not go down because he miscalculated the location of the tank, placed it in the wrong seat and it was far from the blast radius. It was also was too far inside to punch an exterior wall.
A whiteout bottle is about 1oz. IMO, a crude high explosive of that size can bring down a plane under certain conditions. A shaped charge of that size most definitely will.
Nicely explained. I offer as a counter argument Aloha Airlines flight 243 of April 28, 1988.