Its so close to going Bert... You could give it more nose up in the ground stance but that could make for a tricky takeoff even if it went off the grass as you would be leaving with lots of up elevator in a high drag condition. Better to find a field that offers less "resistance". It looks to have plenty of power for a delta and once it breaks ground I think you will have a winner. I love deltas and have flown quite a few. They are odd as they are a very efficient planform once "on the step" but sometimes its tricky to get them there. I have done a few models of the Iconic Canadian Avro Arrow. Most flew around at very low power settings once airborne but took a good push to get them going. Also be careful getting them too slow and getting the nose up as they can become unpredictable and hard to get "on the step" again. Your design, like a jet, lacks the low speed flow over the controls.