I just finished Flight of Passage by Rinker Buck and recommend it to you. It is the true story of two boys, ages 17 and 15, who totally rebuilt a Piper Cub airplane over the winter of 1966/67and then flew it from New Jersey to California the following summer – without a radio. I don’t know if you can even do that now!
Lots of flying information and adventures, and a mention of New Holland airport. Yes there really was one. It was where Airport Drive and Runway Avenue are now, not far from New Holland Elementary School. If your grandparents are from New Holland, they will remember it.