by Tow Itch Mon 06 May 2013, 11:56 pm
Think I misread or misunderstood a part of the above.
According to the head of Bath University's group looking at caravan stability the mass of the caravan doesn't affect its desire to be stable or unstable. So the relationship of the relative mass of the trailer and towing vehicle is not important.
I'll hold with the mass not affecting the desire of a trailer to be stable or unstable as that is what they said.
I think I need to cancel the statement about the relative mass of the trailer and towing vehicle being unimportant. The trailer will behave in the way that it's own dynamics determine but the affect on the towing vehicle will be affected by their relative masses.
navver wrote:The yaw inertia will be higher with a heavy trailer and with a longer trailer.
The nose weight distribution will require a noseweight higher than the towing vehicle can tolerate with a heavier trailer.
Trailer axle position will affect noseweight.
So these things are measurable factors which affect whether a snake will occur or not but they are closely related to the weight and length of the trailer relative to the towing vehicle. So with a heavy long trailer there will be more of these factors. Both factors are very closely related to the loading and resulting weight distribution of the trailer.
A heavy car will be able to withstand more yaw inertia, nose weight and hence greater axle distance and a long heavy trailer will produce more of it.
"The yaw inertia will be higher with a heavy trailer and with a longer trailer.
The nose weight distribution will require a noseweight higher than the towing vehicle can tolerate with a heavier trailer.
Trailer axle position will affect noseweight."
It might be higher but you can have a high mass contained within a smaller volume. The increased mass could be at or closer to the axle. Old trailers with solid floors tended to be heavy but not as long.
A high mass trailer does not have to have a high noseweight indeed in both the Bath University and Collyn Rivers articles there are several statements about suitable noseweights not being linear to trailer weight.
"A heavy car will be able to withstand more yaw inertia, nose weight and hence greater axle distance and a long heavy trailer will produce more of it."
A heavier and certainly a long towing vehicle could withstand greater forces from a trailer. Though a vehicle with a greater distance from the rear axle to the hitch point will also create more instability because it magnifies any sideways movement of the rear of the car.