i have done some air show flying with foamies with streamers. i use the thin neon materal you can find at home depot for marking off land. it's about 1 inch wide and i usually make them about 7 to 8 feet long. i have tried them on planes with alot of power and planes with just enough and i have had found no power effects from the streamer, just have to be carefull in snaps and stalls to keep them from getting in the prop!!!! lol. trust me i have learned this one!!! but i had one of the balsa products extra 32" wingspan models with an hacker a20-20l motor and put 8 foot stremaers on each wind tip and i had no trim change or change in flight time.

mike