Which is why it is better to bench run than to fly the plane. If it is running hot you can shut it down or richen the mixture. In the air you may not notice before the engine is fried. Also you would have to hold on the model to be as save as a bench. I do not trust the stabilizer to hold the model for more than a short run to adjust the mixture. I have seen them fail to see the model shoot off the end of the stand.