A simple test, next time you are out in the car stick your hand out of the window (if its safe to do so) keep it flat and you will find very little resistance, tip your hand forward (like a caravan nose down) and you will find your hand pushed down towards the floor, now tip your hand upwards (like a nose high caravan) and your hand will rise with quite a bit of pressure in to the air, now cup your hand to give a smaller area at the back than the front and you will struggle greatly with the amount of lift generated. this is exactely as it was described to me and exactely as it happens to a caravan which is nose high, as for the car pushing the air away from the van ? why does fuel consumption rise so much its not all down to weight i know ive seen my fuel consumption rise dramatically when towing in to a head wind. Sorry to be argumentative but i really do not believe that either of the clubs would give information that had not been thourally researched.
Fuel consumption increases because of the large frontal area of the caravan and the high drag coeffiecient of something as boxy as a caravan.
What you are describing with holding your hand almost flat outside the window when travelling at speed has little resemblance to airflow around a caravan. If you hold your hand vertically instead you will notice an enormous force against it. If you can then imagine that this has to be held back by something at the bottom of the hand (resembling the reaction of the towbar), you will see that the hand would be rotated backwards. This rotation manifests itself as front end lift in the case of a caravan. That's why it's so important to have enough static noseweight, so that dynamically there is still a downward force on the towball. An outfit will become potentially unstable as soon as the air drag at speed is so high that it causes the towbar to lift, thereby reducing the rear axle load of the towcar even further.
What you are describing with holding your hand almost flat outside the window when travelling at speed has little resemblance to airflow around a caravan. If you hold your hand vertically instead you will notice an enormous force against it. If you can then imagine that this has to be held back by something at the bottom of the hand (resembling the reaction of the towbar), you will see that the hand would be rotated backwards. This rotation manifests itself as front end lift in the case of a caravan. That's why it's so important to have enough static noseweight, so that dynamically there is still a downward force on the towball. An outfit will become potentially unstable as soon as the air drag at speed is so high that it causes the towbar to lift, thereby reducing the rear axle load of the towcar even further.
I was refereing to lol's suggestion that the towing vehicle would remove most of the air form the caravan which as you have also pointed is not correct as the van is much larger, of course this is going to increase drag, what i was trying to demonstrate is that there is still a serious amount of wind present to effect the van. now as you point out with enough speed the van will create lift on the hitch now couple this with a nose high attitude even with enough nose weight and the effect of the wind going under the van with a reduced out let area at the rear will create lift and inherant instability. try carrying a six foot piece of ply wood down the road on a windy day and see what happens then imaginee it being twenty odd feet by 7 feet wide at sixty mph. as i said before i have attended both club towing courses and it was dealt with in great detail that a nose high attitude was a definate no no.
Hi Tony i tow with a ford Mondeo estate 2 litre 130 BHP estate and a Nissan Terrano which is a 2.7 125 BHP ,and i allways travel along motorways at 70 MPH ,because when i was doing 60 MPH i had trucks driving behind me a foot away from the rear of the caravan , and i sometimes use the third lane ,i was in the second lane once with a truck in front of me and a truck right up my rear ,i couldnt see in front i was to frightend to brake so the only option i had was to put my foot down and pull into the third lane to escape , joby
Can I answer this tomorrow? Just noticed your reply Icemaker and would like to reply but it will take me some time. (Slow typer)
Hi Toby - your statements re driving over the speed limit and in the 3rd lane and the reasons why would have be no excuse if pulled in by the police.
I have found that in the main that most HGV drivers are very good and the pests these days seem to be coach and box van drivers.
I have found that in the main that most HGV drivers are very good and the pests these days seem to be coach and box van drivers.
I think you have not read this post correctly Shiraz.... I go back to me guess about you and your profile. I dont condone speeding and you called me dangerous...I do 60 on a motorway! You admit 50MPH is your speed. Are you being a hypocrite ?? You are one who preaches about speeding. Sorry to bring this up again but you are full of Cr4p! Drive to the conditions is one thing but 50mph on a clear motorway is stupidity.
"I just feel that some seem to enjoy preaching about speeding and driving 4x4s whereas the real issues are dangerous driving; driving under the influence; driving whilst being uninsured. the list goes on.
So the next time a powerful outfit overtakes you at 60 mph+ perhaps the more appropriate response would be to question whether or not the conditions are suitable or not. As people have suggested, if the same happened in France none of you would notice; but because we are in Old Blighty that doesn't automatically make it more dangerous, it just means that one has broken the law, and risks being fined etc."
Hi every one
Just back from the Hospital with new valve in the old ticker and now I really do tick !
Observation for Joby,
If you were so close to the vehicle in front, and you believe the lorry behind was within a foot of your caravan, what would you have done if the lorry in front had started to brake?
Realistically, it is unlikely that an experienced HGV driver would endanger themselves by driving so close to your tail, I I am willing to bet that it was considerably more than 1 foot. And on the other side of things, Why were you so close to the lorry in front as to make it a matter of concern to brake?
Like Shiraz, I believe your explanation and reasoning about using the offside lane and speeding would win you no friends in the police force and courts.
Give yourself enough room to drive and manoeuvrer, If that means slowing down then so be it.
Just back from the Hospital with new valve in the old ticker and now I really do tick !
Observation for Joby,
If you were so close to the vehicle in front, and you believe the lorry behind was within a foot of your caravan, what would you have done if the lorry in front had started to brake?
Realistically, it is unlikely that an experienced HGV driver would endanger themselves by driving so close to your tail, I I am willing to bet that it was considerably more than 1 foot. And on the other side of things, Why were you so close to the lorry in front as to make it a matter of concern to brake?
Like Shiraz, I believe your explanation and reasoning about using the offside lane and speeding would win you no friends in the police force and courts.
Give yourself enough room to drive and manoeuvrer, If that means slowing down then so be it.
Welcome back John. Now take it easy for the first few days, but after that we want you doing the dishes, hovering and windows as per normal.
;o)
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