At 14lbs thats gonna be tough, its hard enough for a 14lb byron jet to get off of grass. And how short of a field are we talking? Bigger wheels may help a little, and the only other thing I can suggest is moving the CG back a little or maybe moving the rear wheels forward a little so that the plane can rotate easier, but if it does rotate be careful it will be flying slow and easy to stall, if it does get off you will need a clear and flat area ahead of you, keep it low and level until you pick up speed, if there are any obsticals at the end of the runway don't even try it. 14lbs on a Dynamax fan from grass will be very tough.