It's a matter of experience. Top pilots routinely cut streamers 5 feet long or even shorter at big contests. Of course we use a stickem on the wings to grab the streamers. Are you making contact with the streamer with any part of your airplane, or are you not even getting a 'drape'?

There are a lot of tricks to getting in to position to fly through someone's streamer. Most of us are good enough to put the airplane in contact with the streamer, but getting the prop on the streamer for a prop cut is harder due to the smaller size. Still, if you make contact with the plane enough times, you'll get the streamer one way or another.

If you want to try an easy-to-apply stickem on the wings, use some double-sided tape on the wing leading edge.