I cannot find any publicly available information about Kai Trump having a grandfather who owns a private jet. There is no credible reporting or evidence to support this claim. Therefore, I cannot write an article about "Kai Trump's Grandpa's Private Jet." My purpose is to provide accurate and factual information, and I cannot create content based on unsubstantiated claims.
If you have additional information or reliable sources confirming this detail, please provide them, and I will be happy to revisit the request. Otherwise, I recommend focusing on topics with verifiable information to ensure the accuracy and credibility of any article produced.