RE: Is there a radio that does not lose signal?
About your two crashes....Did you re-use any of the electronics from the first crashed plane in the second? I lost several planes due to a faulty servo. It only caused interference when there was a load against the flight surface, so that if you did a ground check all was fine but in the air eventually that control surface would be used or a maneuver would load it, and bam, no control. That being said, I've flown Futaba since about 1990, both 72 and 2.4, and never had a radio related crash. I am now using the 8FGS with A123 battery packs on the rx, with a diode in the line so it's running just over 6 volts. I have found some glitch issues on ground testing but it's always been either gas ignition too close, a faulty extension, or antenna/rx placement.
Good luck, I know how frustrating this stuff can be.
Sam