Noseweight advice
Comments
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Who has said that the towbar or A-frame doesn't weight anything
well actually you did!
Who cares what the A-frame (or the baby) weighs? The towbar certainly doesn't so its not part of the noseweight
Perhaps you didn't mean to say that but read it? If you meant the weight of the towbar has no affect on noseweight then put your van's jockey wheel on a bathroom scale and a few of you stand on the towbar
Your arguments are very theoretical and seem to disconnect with their actual impact in practical real live situations.
mmm, interesting point, perhaps you should google engineering disasters and look at some reasons? Miscommunication is a large one, namely imprecise language and assuming the obvious, or assuming the other person sees it as obvious, has happen in a lot. usually by engineers not following the theoretical aspects by people who know what they are talking about. See Hyatt Regency walkway. If you find my physics theoretical at least it is totally correct, you are somewhat cavalier with yours. By any chance do you work with VW emissions?
Oh, few things g varies here on the surface of the earth, and g on the moon is 'supplied' by the moon itself not from earth. Your outfit would weight a max of about 75 Kg more depending where it was on the earth, interesting? Well it is to me
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what really? Ok, weight is a force and relies on gravity to function. Mass is simply the amount of matter with a body. It is constant no matter where you are in the universe (actually there are some theories about inside black holes but moving on). Weight is Mass x g (acceleration due to gravity) As gravity is an inverse square law, the force of gravity, or g, varies with the reciprocal of the distance to the centre of the earth squared. So as the planet is not a perfect sphere, it's fatter around the equator than the poles, and it's got hilly bits all over the place, so this distance changes and hence g changes. And then the change in gravity due to local geology, as density affect gravity. Add in centrifugal force as well.
Pass the digestives?
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Now look Corners, I'm following this to the letter
but although my English grades were only average, you will have to come see me after class After all, a slip up in a word could spell disaster theoretically, luckily in the real world it matters not 
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ok before anyone points out my mistake, 25kg, mistyped
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LOL no, very true, I hate tablets.
You are wright tho. When students ask me why I studied maths I always used to say, I can't spell and I can't add up, what else was their?
(yes I know)
I recognise that people view and treat the world in different ways. maths people want the absolute, while Lutz sees the practical I admit. I did say he was right a few hundred pages ago, there is room for both and a bit of fun in debating the difference. Used to do it a lot while studying round at the Cross Keys in Cottingham with maths v physicists v engineering students. Used to get quite heated and only the local brew and fish and chips later kept the peace or is it piece?
No offence meant to Lutz if it came across that way
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Indeed it does, a body will lose and gain mass (ie fat in my case) all the time bits will get worn from tyres. I meant if in an insatne a body has 5 Kg of mass and it was instantly transported to Mars, it would still have 5kg.
Ok (lovely custard creams) here's the next question: where does all this lost matter from radio active decay actually go? and what does it do when its gets there?
Nice coffee
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Posted on 10/11/2017 15:21 by Cornersteady
Who has said that the towbar or A-frame doesn't weight anything
well actually you did!
Who cares what the A-frame (or the baby) weighs? The towbar certainly doesn't so its not part of the noseweight
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I didn't. I only said that they are irrelevant to the discussion. As far as the towbar is concerned it doesn't matter what the A-frame on its own weighs. It's the load exerted by the whole caravan on the towball that counts.
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where does all this lost matter from radio active decay actually go? and what does it do when its gets there?
Why ask me .... I'm an engineer! I presume given a chance it will go hither and thither and of itself might further decay or form an inert substance or gas.
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I haven't followed this thread since about page 4 and now its got 10 more pages. Seldom have I read so much fuss & bother on a subject of caravanning before. I have caravanned since 1977, so about 40 years! I have always ensured that my car to caravan weight ratio was well within recommended limits, and that my car was well maintained and well powerful enough to tow my van with consumate ease.
I have always preferred big and powerful cars with minimal rear overhang and as a result not really worried too much about nose weight, apart from always following the well documented advice on proper load distribution in the caravan itself.
I suppose that at each van change I have checked the nose weight the first time of hitching the new van up, but hardly ever after that. What I have done, was always to take a few steps back to ensure that the rig itself was riding level. In a previous occupation, I dealt with many accidents caused by instability - almost certainly caused by bad loading, causing a nose high attitude. Why do so many caravaners not realise that a nose high attitude encourages too much air flow underneath the van and then instability?
I agree with JVB66 in theory, that your insurers might have some indigestion resulting out of paying a claim for an accident thought to be caused by a nose weight issue. But in practice the devastation caused to almost all the vans that I swept of the road after an accident, I would challenge any one to prove what the nose weight had been!!
Seriously there has been an awful lot of Technical advice levelled over these pages, but you really don't need a slide rule on this just common sense. (1) Is your car/van ratio within guidelines (2) are they both properly maintained, engine wise and suspension wise. (3) Is the car and clutch strong enough to do the job? and finally and most importantly (4) Load your caravan sensibly, having regard for all the advise available, & is it hitching up level? All OK? Then you'll have a good holiday!
TF
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That a nose up attitude is inherently responsible for an unstable outfit is a myth. At the sort of speeds that caravans are towed, the differences in aerodynamic flow between nose up or nose down are negligible. Caravans are too big and boxy to have anything like aerofoil properties.
A nose up attitude simply only 'looks wrong' and reduces ground clearance at the back of the caravan, but it is otherwise of no functional consequence.
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A nose up attitude simply only 'looks wrong' and reduces ground clearance at the back of the caravan, but it is otherwise of no functional consequence.
However given the normal range of towbar heights and hitch heights a caravan that looks markedly up at the front could well be badly loaded perhaps. I say this because it is not something that I have often observed.
More often likely to see one very low down at the front with car rear sagging badly
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but it's given off as energy isn't it?
Anyway, back on topic, like TF I have only checked nose weigth with a new van, empty at first, then half full then fully loaded for long stay. I'm also a creature of habit and will pack the van the same way each time with those blue IKEA bags that when full weight about 6Kg (anyway done centre out) so if it was OK for the three trails it should be ok ever since.
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well no I'm with TF on this one. Under braking a nose up attitude could cause instability problems. I know you won't believe me but:
If the caravan is “nose high” this can have an effect under braking and reduce the stability of the towing vehicle and caravan. The normal cause of this is the hitch height on the towing vehicle being too high, even with the correct nose weight, this could cause instability problems. As can be seen (right) we have a similar situation to braking with the caravan not being aligned with the towing vehicle. In this case, the forces acting as the caravan “pushes” into the rear of the braking vehicle are not in line and have the slight effect of trying to “lift” the vehicle’s rear end. This is also compounded by the fact that under braking, the vehicles centre of gravity moves forward, transferring weight to the front wheels and off the rear wheels so the rear of the vehicle
taken from here, so a nose down attitude would mean, under braking, that the van pushes downwards.
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As I said! Ensure that the rig is even. Neither nose up Or nose down!
40 years of many thousands of miles, with no incidents, let alone accidents, must tell you something! Get the loading right! Do not get in a lather about an exact nose weight!
TF
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Nose weight as important as it is re stability is far from the only weight [well mass really] aspect of loading that needs to be right. The distribution of those collections of masses, so the moment of inertia is very important too.
IMO a factor, so often forgotten or not understood, often in the drive to the correct nose weight.
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Just to help perpetuate this long-running thread on simple issue... Under heavy breaking, the nose of a car will dip thus raising the hitch. Even a level caravan could thus end up in a nose up attitude.
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Are you changing your mind now a bit ? you did mention a nose up being the cause of possible accidents: I dealt with many accidents caused by instability - almost certainly caused by bad loading, causing a nose high attitude. and when leaving is it hitching up level?
Now you're saying nose up or down?
Personally a nose down attitude is better, probably not going to make that much difference but under severe conditions or braking it all helps, as I described before.
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Why, with correct nose weight, can a nose up attitude cause instability? When the caravan's brakes are applied, the front end will always tend to dip, the same as the car when its brakes are applied, and that is so regardless of whether the caravan's nose was already down in the first place or nose up.
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suggest you direct your questions at that website that I took the quote from(did you look at it?) https://caravanchronicles.com/guides/understanding-the-dynamics-of-towing/
It seemed convincing to me and I agree with it's findings. But perhaps you could go into the forces and moments and prove your statement to contradict their findings? as maybe it's not that obvious?
also are you contradicting one of your previous posts? that nose weight is less when you have a nose up attitude?.
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"https://caravanchronicles.com/guides/understanding-the-dynamics-of-towing/
It seemed convincing to me and I agree with it's findings."
The "chronicler" seems to have forgotten halfway through the van is not an unbraked trailer but has its own brakes. So unless its braking is ill set up the forces it transfers will be low in magnitude.
Plus they are simply assuming the van's centre of mass is located vertically inline with the axle; that the nose weight varies much when lifting and lowering the hitch of particular vans indicates that there that is not the case. Realistically it must be higher than the axle as all but everything is physically above the axle.
I do have my suspicions that the nose up attitude would bring in "ground effect" wedging of what air is getting trapped under the van? This coupled to the tipping from the drag forces on the front of the van both contribute to lowering the dynamic nose force. Not the best of news re stability.
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Posted on 11/11/2017 09:51 by Cornersteady
also are you contradicting one of your previous posts? that nose weight is less when you have a nose up attitude?.
I see no contradition. A nose up attitude will result in a slightly lower nosweweight, but this will increase again under braking, just as it would nose down. Besides, the difference in static noseweight between nose up and nose down is minimal compared with the dynamic forces that occur under braking and disappear into insigificance in the resultant net effect.
The 'caravanchronicals' article has a number of shortcomings that don't stand up to scrutiny.
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The thing is Lutz, and don't get offended by this, but it's a pattern that you state things like the website has shortcomings that don't stand up to scrutiny or that nose up will reduce nose weight and you expect us all to accept your statements as if they are true? For example it is so easy to say that about the website but you don't say how/where these shorting comings are or how they do not stand up to scrutiny. Equally you never give any real maths/physics behind your statements, just assuming we accept your profound knowledge as gospel.
Yes my reasoning and the underlying maths is pedantic, I gladly admit it, I was 'educated' not to make mistakes which are easy to do in mechanics, where things look to be explained but aren't, hence how Newton really showed what was happening rather than the errors in Aristotle's physics (heavy bodies fall faster than light ones is a classic case which seems true but isn't) which everyone accepted for a few thousand years because they appeared to work.
But while pedantic no one has pointed out any errors in my maths/physics (while plenty in my use of English
) and I can show things to be true.So how does nose weight decrease when nose up and increase when nose down. It's a clockwise moment whether (or is that weather) above or below the horizontal? Over to you.
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"So how does nose weight decrease when nose up and increase when nose down".
Is this seriously in question?
Relative to what it is if horizontal and moving within realistic amounts.
Because the van's C of G is located higher than and forward of the wheel axle shafts.
So lowering the nose moves the C of G forwards away further from the vertical through the axles and the hitch lever length reduces. Lifting the hitch also shortens the lever arm but the C of G moves backwards more towards the axle overcompensating this.
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Thanks but it was aimed at Lutz, who I hoped would have provided a explanation rather than one if his statements.
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I think ocsid explained quite well. I would have said about the same, but using other words. Tipping the nose of the caravan up shortens the horizontal distance between the centre of mass and the axle, hence reduces the moment about the pivot point (the axle). As, at the same time, the horizontal distance between the hitch and the axle remains virtually unaltered because hitch and axle are roughly at the same height, the force at the hitch will also reduce.
In the case of my small trailer one can tip the nose end up so far that the centre of mass moves behind the axle, so the noseweight crosses zero and turns negative so that the trailer stays like that on its own until physically pushed down again.
To go into details of where the 'caravanchronicals' article doesn't stand up to scrutiny would be beyond the scope of a forum thread like this. In order not to bore other readers it would have to be discussed separately elsewhere.
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To go into details of where the 'caravanchronicals' article doesn't stand up to scrutiny would be beyond the scope of a forum thread like this. In order not to bore other readers it would have to be discussed separately elsewhere.
Ok I'm sure that's what VW said when first confronted with the emission scandal
BTW Lutz you do realise as a teacher I've heard the cop out stories? In my youth I probably wrote a few
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