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Comment by dotancohen | Hacker News Reader

  > fuel doesn't care about the bobbing up and down

Maybe the fuel doesn't care, but the flight crew certainly will care about a large oscillating mass constantly changing the aircraft's center of mass.

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Baffles are typically used to control this, even in conventional aircraft fuel tanks. It's a non-issue.

I mean, baffles aren't free, since they add empty weight and reduce payload. The designers will be tempted to keep them to a minimum. There definitely will be at least some free surface effect and slosh.

Plastic bags to reduce slosh?

Plastic bags to vomit in.

Is it drastically different from conventional aircraft though? The KC-135 houses a great deal of it's own fuel in the wings as well. So does most commercial air liners AFAIK.

30% more efficient according to the article.

Surely the fuel will be separated in to multiple tanks with pumps between them, similar to conventional aircraft.

Wonder how much a computer can dampen/remove/counter these sloshing events by constantly adjusting the control surfaces. super interesting stuff.

What about an isolation platform aka a pilot cockpit and boom operator gimble?

I agree the computing tech should help a lot! Seeing what experiments were done with the ground effect RC project (what’s his name, cool YouTube vids) indicates the software exists or will soon for a large craft. Especially because this will be generation 3 of a flying wing!

> the flight crew certainly will care

How long will tankers be crewed?

The new Navy MQ-25 tanker is uncrewed. I expect this future Air Force tanker will be optionally manned. The main issue is that Air Force tankers use a boom system which requires an operator onboard to manually "fly" the boom into the receptacle. In theory that could be automated but it's a difficult technical problem. Navy tankers use a simpler drogue system which doesn't require a boom operator.

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