Noseweight Technicalities

[Ian_5040589]

I spent a couple of hours on our new Swift Challenger 540 yesterday, preparing it for a holiday next week (can't wait).

I always battled with our previous van to get the noseweight down to my towbar limit (85kg) and usually had to take out one of our two 4.5kg gas bottles.

The Challenger seems to be a different story completely - I had to replace an empty gas bottle to get the noseweight up. After years of battling to keep it down this seems odd! The noseweight measured around 85kg with the jockey wheel off the ground, although I think the front of the van was slightly nose down compared to how it rides level on the car. I guess this would make the noseweight slightly lighter?

The new van is a fixed bed, with the cooker etc over the axle and the wheels in the middle of the van. Presumably the weight of the bed at the back has some effect.

Our previous van was a 5 berth twin dinette with the wheels set back towards the rear. I guess this may have forced the noseweight up?

I guess it just goes to prove what an in inexact science caravanning is!

 

[Rod_5041370]

Wheels set towards the rear should produce a lighter noseweight.

 

[Lutz]

The noseweight should always be measured with the coupling at the same height as when the caravan is hitched up to the car and this is not necessarily in the level condition.

If you measure noseweight with the caravan level and then find that it is nose down when connected to the car, the actual noseweight will be higher than what you measured.

 

[ShadySadie]

I'm still mystified by these nose weight problems, a reply in the question about rear of caravan bike rack makes me wonder if some caravanners think they can just fill the cupboards and wardrobe space with the families requirement and then wonder why the nose weight is way out.

 

[Ian_5040589]

So am I right in thinking that if the noseweight is 85k with the noseweight guage taking the full weight of the van at the front (ie jockey wheel off the ground) the actual noseweight is lighter as the van is slightly nose down whereas it rides level on the car?

 

[Lutz]

If the noseweight is 85kg with the caravan level, it will be more when you lower the front end and less when you raise it.

 

[Ian_5040589]

Thanks Lutz.

It just seemed odd that two vans of similar MTPLM and similar overall length could have such differing noseweights.

I guess layout must have something to do with it. The new one seems to be much more stable towing which I have put down to the cooker and fridge being right over the axle, whereas previously the cooker and fridge were infront of the axle.

 

[Chrisbee]

Wheels set towards the rear should produce a lighter noseweight.

I think you'll find that the further back the axle, the greater the nose weight.

 

[Lutz]

Definitely the layout has a very important influence on the location of the centre of gravity of the caravan relative to the axle. However, modern CAD design techniques allow caravan manufacturers to calculate the position of the centre of gravity without even ever having built a prototype. Therefore, there is no excuse for caravans leaving the factory without an acceptable noseweight.

 

[Rod_5041370]

I think you'll find that the further back the axle, the greater the nose weight.

Really!

 

[Glenn_5132962]

Calculating weight & centre of gravity is what I do for a living! (On aircraft, not caravans).

 

[Lutz]

With due respect for what you do for a living, Glenn, but the CAD techniques that I referred to do not require anyone to calculate centres of gravity. Just by entering details of the material into the computer, the software will automatically do the calculation of weight and centre of gravity of each component for you based on its design math data. Knowing where each component will be located in the assembly (in this case the caravan), the sum of weights will give you the total calculated weight of the caravan as well as its overall centre of gravity. There really isn't anything that anyone has to do. It's all done for you.

 

[Reg]

Lutz

If only life was that simple........ I have spent quite a long time in CAD/Software applications.

But if you are happy with your analysis then thats fine.

 

[Lutz]

Maybe in your case, the automatically generated data is not accurate enough for aircraft applications but from my experience in the car industry, it is perfectly adequate and would certainly be OK for caravans where a couple of kilos either way in total are not going to make any difference.