Investing In a Friends Business

They’re planning on building a new airport in my town but they’re looking for support and a few small businesses to open up inside of the airport. A close friend of mine has been flying small commuter planes for a few years now but he wanted start his own small aircraft charter company. He asked me to come in as an investor. He said that it would be great and the revenue would be substantial because the next airport is over 350 miles away. I told him to draw up a business plan and shoot it over to me so I could decide to invest or not.