I had a great flight with me Klima Auriga that I modified as a two-stager with a cluster o' four motors on each stage. This flight was flown with 4 x D9-5 in t' booster and 4 x D3-P in t' sustainer. T' on-board camera added weight and a lot o' drag. Blimey! This made t' D3 motors struggle t' accelerate t' sustainer. For this setup D9 motors in t' sustainer would be a better choice.