1/4 scale B25 ..... the video explanation on YT explains that he nearly loses it near the end as the undercarriage is not locked down - brilliant save - only a few seconds after saving it listen to the engine note suddenly rise - then he loses it completely due to catastrophic engine failure
The loss was due to the wooden prop rubbing against the engine nacelle and burning through and snapping off in flight
The very last shot of the video is of the damage to the offending prop 
This is such a basic error you'd have thought somebody would have spotted that - or felt it when turning the props over
