As the campaign season heats up for the November 25 polls in Rajasthan, charter rates for helicopters have doubled or even tripled. Single-engine choppers that were available for Rs 1 lakh per hour until six months ago now cost Rs 2 lakh or more, while double-engine choppers have almost doubled to Rs 3-4 lakh. The demand for helicopters is expected to increase further as more candidates are declared for the elections.