Stupid Questions May 2015

Gondolinian

This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.

Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.

To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.

Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.

To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.

I see, that makes much more sense now. Thank you!

So I (now) understand that rockets are designed to be thin and light to reduce drag and gravitational forces. As far as the cost-benefit of adding a protective layer, the cost is the added drag/gravitational forces, but the benefit seems to be huge (able to land it in water). Is it really that hard to generate the necessary propulsion forces?

Obviously the answer is "yes", but that goes against what makes intuitive sense to me. Can you explain?

I think part of the problem is a fundamental misunderstanding of what parachuting into the ocean does to a rocket motor. The motors are the expensive part of the first stage; I don't know exact numbers, but they are the complicated, intricate, extremely-high-precision parts that must be exactly right or everything goes boom. The tank, by comparison, is an aluminum can.

The last landing attempt failed because a rocket motor's throttle valve had a bit more static friction than it should, and stuck open a moment too long. SpaceX's third launch attempt - the la... (read more)

0Viliam11y

Each additional kilogram of the rocket is probably extremely expensive. I don't how much weight would that extra protective layer add, but I can imagine it could more than double the weight of the rocket, and the weight of the fuel it needs, etc.