Kerbweight v 85% ratio

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Jul 18, 2017
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Well for the first time ever with our current caravan we have the porch awning inside the caravan and I am quite happy.
 
Mar 14, 2005
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I am with the Prof on your statment, going to the Max permissable nose weight is not always the best. Also caravans do not always lift as going along as the airflow overthem, is not a true aerofoil. . But yet again we are getting away from the Original posters Question, about Kerbweight.
And into the " Pandorras Box " of nose weights.
The projected frontal area of a towed caravan above the roof line of the towing vehicle is normally quite large. In view of the fact that the aerodynamic centre of pressure of that exposed frontal area is so far above the axle height, the resultant couple will always cause the noseweight to decrease with increasing speed. In fact, at some stage, it can even result in negative noseweight. For that reason, adequate noseweight is absolutely essential. Only structural constraints limit the ultimate degree of noseweight applied. Sources in the UK often recommend 7% of the total weight of the caravan although in many cases this is more than what the car manufacturers allow and therefore not achievable. In the USA and Australia they even recommend 10% and that is even less possible in our part of the world.
In Germany, one of the requirements that must be fulfilled in order to receive a concession to be allowed to tow at 100km/h instead of the regular 80km/h is that the noseweight must be set at the max. limit prescribed by the manufacturer.
 
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Mar 29, 2021
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I am with the Prof on your statment, going to the Max permissable nose weight is not always the best. Also caravans do not always lift as going along as the airflow overthem, is not a true aerofoil. . But yet again we are getting away from the Original posters Question, about Kerbweight.
And into the " Pandorras Box " of nose weights.
The lifting effect isn't cause by aerofoil but by the front of the caravan hitting air resistance this causing the hitch to lift.

If you push your hand, the wind resistance, against the front top of a suitable object, pop bottle in my case, the base of this lifts up, that in effect is what happens whilst we tow.
The greater the speed the more effect the hand has.
 
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