As an american my novice view of the USSR was that they had huge problems with production, organization, infrastructure, and corruption. Spread out over an entire country it seems like these things would cripple their economy. I understand that the USSR eventually fell (probably contributed to by these things) but how were they able to keep up with the incredible economic might of the post-war USA for so long?
The Soviet economy had enormous problems with consumer goods. The centralized economy was very bad at planning, creating and distributing them and there were chronic problems with shortage. When people think of the problems of the Soviet economy, this is generally what they are thinking about. Shortage, waste, problems with quotas, etc.
However, the centralized economy was plenty good at major economic projects. Mass industrialization in the late 1920s and early 30s, converting the economy for World War 2 (including moving many factories literally brick by brick eastward to protect the industrial infrastructure), and cold war military projects were all things that the Soviet economy did well (if often at great human cost!).
Furthermore, the Soviet Union had enormous natural resources at its disposal. I actually just wrote about this the other day so I'll copy that again here:
That all being said, it's also very clear that later on the abundance of oil played a HUGE role in keeping the Soviet economy humming along. Stephen Kotkin talks a lot about this in the opening to his retrospective on the disintegration of the Soviet Union Armageddon Averted. He (and others) argue that it oil really saved the Soviet economy in the 1970s and when global oil prices dropped, the Soviet economy suffered greatly, including during the 1980s when things ultimately fell apart. So, I think you can make an argument that the Soviet economy really did depend a lot on the natural resources on which it stood. This was particularly important to the Soviet economy in the last 20 or so years of its existence. However, the economy to extract and distribute those resources had to be built essentially from scratch by the Soviet state - and it did that.
Hey!
I think it's very important to note that contrary to what you would think, the Soviet people were very well educated. School being free, they never had a shortage in scientists/engineers, both being crucial in the industrialization process of the country. Additionally, as was previously said, heavy industry was where the USSR was doing really well, exporting tons of raw materials and weapons all over the world (AK-47 being the most sold weapon in the world).
Considering military spending and keeping up with the US, I believe more than 20% of GDP went to the military to 5-8% in the US (depending on the administration in power) during the Brejnev era, yet both were roughly equivalent.