I have just bought Rhino bars with a Thule roof pod, I did like the look of some of the roof trays though, some had a wind deflector on the front (see the Rhino site). I decided against them as I will only be carrying light stuff and I prefer it to be out of site when parked in towns etc and also better protection from the weather etc. The roof trays will carry a much heavier load though, but the load rating of the roof bars need to be taken into account (some add a third one in the middle, mine only has two).
The shop people told me that you will get some wind resistance with the bars but very little, although the roof trays apparently make a fair bit of noise compared to the pods according to them. You will get some fuel use increase and he said better to remove pods and baskets (roof trays) when not in use. On one of the sites I looked at it had a pod on one side of the roof bars and a narrow basket on the other.
Here is a pic of mine, Rhino bars and Thule pod, the side rails were already on the vehicle;
-- Edited by Duh on Sunday 10th of November 2013 03:32:04 PM
-- Edited by Duh on Sunday 10th of November 2013 03:38:49 PM
I recall either choice or NRMA doing tests through some areo engineering school on the effectiveness of wind deflectors .
The item below is a statement that came from a Canadian assessment of deflectors on their version of our semi trailers ( Tractor Trailers ) , there is a lot of writing on the subject on the net if you are in need more confusion in your life .
"Since aerodynamic drag is but one source of fuel consumption, it is important to understand its effects on overall fuel consumption. At 80 km/hr, a 20% reduction in drag will contribute to about a 10% reduction in fuel consumption. These fuel savings would rise as speed increased to a value of approximately 15% at 120 km/h. Examples like these are over-simplifications of higher-order engine specific calculations; however, they do provide a way to estimate the contribution to fuel burn from aerodynamics at various vehicle speeds."
-- Edited by Wombat 280 on Sunday 10th of November 2013 06:38:29 PM
-- Edited by Wombat 280 on Sunday 10th of November 2013 06:39:50 PM
elliemike said
11:49 PM Nov 10, 2013
No matter what shape you put up there it will create resistance.
Some streamlining shapes offer less resistance than others. But you still have to drag that silhouette/cross section through the air.
I dont think I have ever seen any comparison figures for these items. Be interesting to see what comes up.
I try to keep the roof bars empty when doing long journeys. Even a shovel strapped up there adds to the fuel consumption.
Duh said
11:58 PM Nov 10, 2013
Do you remove the cross bars too Ellie and Mike or leave them on there when you remove anything on them? Do they make a noise or use some fuel as well?
The chap I spoke to did say they would use some on their own but it is minimal. The luggage carriers and pods though did give an noticeable increase according to him, and the luggage carriers and trays made more wind noise than the pods.
elliemike said
01:59 AM Nov 11, 2013
Duh wrote:
Do you remove the cross bars too Ellie and Mike or leave them on there when you remove anything on them? Do they make a noise or use some fuel as well?
The chap I spoke to did say they would use some on their own but it is minimal. The luggage carriers and pods though did give an noticeable increase according to him, and the luggage carriers and trays made more wind noise than the pods.
I now have an Awning on the Isuzu Dmax so the wing bars and awning are there sort of permanently. As we use the Dmax specifically for trips away.
Coincidentally I took them all off the Dmax yesterday, as I had noticed a fixing fault in the awning attachment to the wing bar. They had used the wrong fixing bolt and it was damaging the wingbar "T" track.
Actually it does not take long to get the awning and wing bars off the roof.
Having done it once I think 30 mins from whoa to finish stored in the garage would be about right.
cultana said
02:01 AM Nov 11, 2013
There is a thread on caravan wind deflectors here on Australia4WD:
Thanks for the feedback Ellie and Mike, everything has a calculated price if you want to use it (eg; airconditioning on the move) I am happy to have my additions for the purpose I had them fitted and of course as you said remove what you don't need when you are not using them.
Interesting about the nose cone Cultana, I was wondering what they were, thanks for the link.
I knew fuel consumption did rise at a certain point Wombat280 and thanks for details. Tyre wear will also increase at higher speeds too according to the experts.
ken thomas said
12:45 PM Nov 12, 2013
closer picture of nose cone
Ken
-- Edited by ken thomas on Tuesday 12th of November 2013 12:46:08 PM
Caravan and Motorhome magazine did a write up on the nose cone some time ago and gave it e thumbs-up. Was mounted on an old Millard and hinged up to access front windows. Its main benefit was that I held the van steadier when being overtaken by semi-trailers because of better airflow around van frontal area.
Peter
ken thomas said
08:44 PM Nov 12, 2013
I have a nose cone on my van and I am happy with it, the van seems more stable when towing and in headwinds. It still gets buffetted around with side winds but less than without it
Check avatar
Ken
hi , has anyone seen a comparison data sheet on these items. i was just looking to see which system to use regarding fuel,wind drag etc.
please let me know, terry. i forgot to mention that i wiil be towing a van around . have seen some ads for nose cone attached to van,
but dont know which would be best, terry
-- Edited by terry and leanne on Sunday 10th of November 2013 06:00:06 PM
If you google Rhino Racks and Thule (pronounced Tool'e or Tooley) that should give you some info Terry. (Edit: Links added)
http://www.thule.com.au/
http://www.rhinorack.com.au/products/luggage-carriers
I have just bought Rhino bars with a Thule roof pod, I did like the look of some of the roof trays though, some had a wind deflector on the front (see the Rhino site). I decided against them as I will only be carrying light stuff and I prefer it to be out of site when parked in towns etc and also better protection from the weather etc. The roof trays will carry a much heavier load though, but the load rating of the roof bars need to be taken into account (some add a third one in the middle, mine only has two).
The shop people told me that you will get some wind resistance with the bars but very little, although the roof trays apparently make a fair bit of noise compared to the pods according to them. You will get some fuel use increase and he said better to remove pods and baskets (roof trays) when not in use. On one of the sites I looked at it had a pod on one side of the roof bars and a narrow basket on the other.
Here is a pic of mine, Rhino bars and Thule pod, the side rails were already on the vehicle;
-- Edited by Duh on Sunday 10th of November 2013 03:32:04 PM
-- Edited by Duh on Sunday 10th of November 2013 03:38:49 PM
I recall either choice or NRMA doing tests through some areo engineering school on the effectiveness of wind deflectors .
The item below is a statement that came from a Canadian assessment of deflectors on their version of our semi trailers ( Tractor Trailers ) , there is a lot of writing on the subject on the net if you are in need more confusion in your life .
"Since aerodynamic drag is but one source of fuel consumption, it is important to understand its effects on overall fuel consumption. At 80 km/hr, a 20% reduction in drag will contribute to about a 10% reduction in fuel consumption. These fuel savings would rise as speed increased to a value of approximately 15% at 120 km/h. Examples like these are over-simplifications of higher-order engine specific calculations; however, they do provide a way to estimate the contribution to fuel burn from aerodynamics at various vehicle speeds."
-- Edited by Wombat 280 on Sunday 10th of November 2013 06:38:29 PM
-- Edited by Wombat 280 on Sunday 10th of November 2013 06:39:50 PM
Some streamlining shapes offer less resistance than others. But you still have to drag that silhouette/cross section through the air.
I dont think I have ever seen any comparison figures for these items. Be interesting to see what comes up.
I try to keep the roof bars empty when doing long journeys. Even a shovel strapped up there adds to the fuel consumption.
Do you remove the cross bars too Ellie and Mike or leave them on there when you remove anything on them? Do they make a noise or use some fuel as well?
The chap I spoke to did say they would use some on their own but it is minimal. The luggage carriers and pods though did give an noticeable increase according to him, and the luggage carriers and trays made more wind noise than the pods.
I now have an Awning on the Isuzu Dmax so the wing bars and awning are there sort of permanently. As we use the Dmax specifically for trips away.
Coincidentally I took them all off the Dmax yesterday, as I had noticed a fixing fault in the awning attachment to the wing bar. They had used the wrong fixing bolt and it was damaging the wingbar "T" track.
Actually it does not take long to get the awning and wing bars off the roof.
Having done it once I think 30 mins from whoa to finish stored in the garage would be about right.
There is a thread on caravan wind deflectors here on Australia4WD:
CARAVAN WIND DEFLECTOR
And it relates to this crowd, Nosecone, who make them in Oz.
NOSECONE
No idea if they work or not.
Thanks for the feedback Ellie and Mike, everything has a calculated price if you want to use it (eg; airconditioning on the move) I am happy to have my additions for the purpose I had them fitted and of course as you said remove what you don't need when you are not using them.
Interesting about the nose cone Cultana, I was wondering what they were, thanks for the link.
I knew fuel consumption did rise at a certain point Wombat280 and thanks for details. Tyre wear will also increase at higher speeds too according to the experts.
closer picture of nose cone
Ken
-- Edited by ken thomas on Tuesday 12th of November 2013 12:46:08 PM
Peter
Check avatar
Ken