My understanding is that labeling it a vacuum tube is a bit of a misnomer. It should be called a low-pressure environment or near-vacuum. Achieving that much

My understanding is that labeling it a vacuum tube is a bit of a misnomer. It should be called a low-pressure environment or near-vacuum. Achieving that much reduction in air pressure will greatly reduce drag and allow for increased speeds. It doesn't need to be in a vacuum.