Disable MAC acknowledgement

Hi, I am working on some radios that are to be installed on a mobile vehicle. I’m currently using routerboards with XR9’s. I’m wondering if anyone knows if it is possible to disable MAC acknowledgement of wireless frames (like 802.11e NoAck policy).

Time critical data is being sent to the vehicle, and it must not be buffered/retransmitted. Any pointers would be greatly appreciated.