The Time Magus by Phyllis Haislip
Approx. 36,210 words.
Published on November 17, 2010.
13-year-old, Jeff’s dad trusts him to test an advanced computer called the Magus. It mysteriously disappears, traveling back in time to 1937. Jeff has to get back the Magus before his father returns. Claire, seriously ill with tuberculosis, finds the Magus. The kids e-mail across time and have to save Claire's family from traveling on the Hindenburg.