Rocketdyne A-7 rocket engine used in the Redstone rockets, on display at the Air Zoo, Kalamazoo, Michigan. The museum sign describes this as an A-6 engine but the nameplate includes an A-7 serial number
<a href="//commons.wikimedia.org/wiki/User:Rmhermen" title="User:Rmhermen">Rmhermen</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>