I tried both solutions, but the problem persists. I made sure that the models were very rigid, and straight landing gears, for now, the only solution was to apply two pairs of LG (front and back), but it is good only for large aircraft, for small planes, Having regard to the limited space, I have to opt for a tricycle gear configuration, and with only a few models can complete a take-off. what seems strange is that the landing gears despite the apparent rigid, during "rush" on the runway, they seem made ​​of jelly also coming to bend 45 degrees