The streaming data over onboard spacecraft and aircraft networks is considered in the paper. The SpaceFibre spacecraft standard could be successfully used for streaming. It is proven by the proposed comparison of SpaceFibre with other network standards. While investigating and analyzing SpaceFibre for streaming, the limitation of the SpaceFibre QoS mechanisms was found. The solution was also proposed. To evaluate its benefits the mathematical approach to quantity calculation of transmitted streaming data via SpaceFibre was develop. The paper is concerned with this approach and the mathematical model of the streaming data transfer over SpaceFibre virtual channels.