Blackstone Group LP, vying with financiers including Citigroup Inc., is starting a new fund to provide loans for a luxury-jet market projected to reach $280 billion over the next decade.

The fund’s creation adds Blackstone, the world’s largest alternative-asset manager, to a growing roster of lenders taking advantage of a business-aviation rally. The fund says it will be able to finance as much as $2.5 billion in plane purchases and will focus on the biggest models costing $30 million or more.