Apple has the pedal to the metal on iOS 11, as it released the second developer beta in a week. iOS 11 Developer Beta 9 (15A5370a) is available now through the Apple Developer Connection for compatible iPhone, iPad, and iPod touch models.
iOS 11 developer betas require an Apple Developer account and an iPhone SE or newer, fourth generation iPad or newer, or a sixth generation iPod touch. The update is available through the iOS Software Update option, or through the Developer website if you haven’t signed up for beta testing yet.
This release does not affect those who are running the public beta of iOS 11.