I cannot find any publicly available information about Kai Trump having a grandfather who owns a private jet. There is no reliable source confirming the existence of such a person or asset. Therefore, I cannot write a complete article about "Kai Trump's Grandpa's Private Jet" based on factual information. Creating content based on false premises is unethical and harmful to SEO.
If you have more information, such as the name of the grandfather or any verifiable source mentioning this private jet, please provide it, and I will be happy to attempt to write an informative and SEO-friendly article based on verifiable facts.