Roofrack measurements

[Gerrit Loubser]

Stefan,

I have a Frontrunner Windcheetah full length rack (By the way, if you still need it, I can also get dimensions of my rack to you, but it seems like you are sorted?). In my experience, the Windcheetah does not cheat the wind so well, or perhaps the wind got upset over being cheated and is now hissing like a cornered rooikat .

I think the reason for the wind noise is the fact that the Windcheetah has only transverse slats. This makes for a sturdy rack with minimum slat span, but all those slats are presented to the airflow transversely as well. I have noticed that some other racks (e.g. African Outback?) have slats that run longitudinally predominantly with a smaller number of widely spaced transverse ones to ensure adequate support. Perhaps you should consider this issue and adapt your design as I notice that you have gone for the transverse slats as well.

The Windcheetah racks get a deflector plate bolted in right at the front between/over the first two slats. This is supposed to help, but mine has this and the wind noise is still significant...

[SRXy]

I have the plate and have little to no noise from my roofrack. I do however make sure that the front of the rack is in the right place aerodynamically when I fit it. If you push it too far forward it creates drag and will make noise.

[JG Shields]

I had the Windcheetha on a previous vehicle, including the noise reduction plate. It is a great roofrack, however it is no comparison to the Outback roofrack ito construction, noise and practicality...especially on the Patrol.

[Sias]

I do however make sure that the front of the rack is in the right place aerodynamically when I fit it. If you push it too far forward it creates drag and will make noise.

Please elaborate? How do you know how far back to go? What length rack do you have?

[Stefan]

Frans: Enige tyd!

Thanks SRXy, do you also have the solid bar at the bottom of the feet?

Gerrit, I'll do that. Luckily the design is easily changeable. I'll probably still fit 2 transverse elements at the B & C pillar feet attachment points.

[Russ Kellermann]

I understand the theory of the "wind cheater" and other low profile racks, but surely this only helps if your rack is fitted permanently, as, in my mind, surely as soon as you pop a jerry can or spare tyre on the thing its not gonna make a hoots difference which way they slats run or how low the rim is, or, how far back. I've never used one so i'm not talking from experience here, yet, i can't see how one can cheat wind with any items actually loaded above, particularly if they are various shapes and sizes, as this would surely cause increased turbulence and in turn, noise (hiss), and resistance.

Stefan, do you plan on keeping yours on full time? I am also building a roof rack to mount on my new alu canopy so all this is interesting.

[SRXy]

I do however make sure that the front of the rack is in the right place aerodynamically when I fit it. If you push it too far forward it creates drag and will make noise.

Please elaborate? How do you know how far back to go? What length rack do you have?

It's an eye-balling thing that I've kinda figured out with putting it on and driving with it and then moving it and driving with it etc. I lined it up so that it runs with the line of the vehicle (as in not overhanging the front windscreen)..this seems to stop it from getting hammered by the wind and keeps it pretty quiet. I have the 2.2m rack so I can do this....and I use a flat bar at the back to mount the rear of my tent onto. Works like a charm....

Of course once you stack it full of crap then it makes little to not difference....I always try (where possible) to keep the front a sloped as possible to ensure that it doesn't create a wind dam and lots of turbulence.

@Stefan: yep....the "feet" have a flat bar at the bottom. They don't clip over the edges, but fit into the rails and then the silver clamp goes over the side (like in your mock-up).

[Gerrit Loubser]

I have the plate and have little to no noise from my roofrack. I do however make sure that the front of the rack is in the right place aerodynamically when I fit it. If you push it too far forward it creates drag and will make noise.

SRXy, could you please post a picture (perhaps a side view) of your Troll with roofrack on so that I can see how your roofrack location compares with mine?

My roofrack is 2130mm long and is mounted so that the rear edge of the rack is vertically above the rear edge of the roof of the car, so the front is far back. It still creates a lot of wind noise...

[SRXy]

I have the plate and have little to no noise from my roofrack. I do however make sure that the front of the rack is in the right place aerodynamically when I fit it. If you push it too far forward it creates drag and will make noise.

SRXy, could you please post a picture (perhaps a side view) of your Troll with roofrack on so that I can see how your roofrack location compares with mine?

My roofrack is 2130mm long and is mounted so that the rear edge of the rack is vertically above the rear edge of the roof of the car, so the front is far back. It still creates a lot of wind noise...

Interesting....maybe it's too far back and hooking into the turbulent air that's flowing over the windscreen..lol? It's not on the car at the moment, I'll dig around and see if I can find any side profile pics from my last major trip.

[Stefan]

I'm planning on keeping the rack fitted to the Patrol permanently. Although if it's made from Aluminium, it should be light enough to remove - storage is always an issue though.

Below is the next evolution of the design, after contacting a lot of the aluminium suppliers down in the cape and finding out who has what stock of which profiles.

Rack:


Foot assembly:


This version uses:
> 50mm x 20mm x 2mm rectangular hollow for the sides and longitudal slats
> 76.2mm x 6.36mm for all the flatbar sections
> 25.4mm x 6.36mm for the 2 "feet runners"
> 8mm threaded bar for the foot fasteners
> Some 1.5mm stainless plate for the 8x foot fasteners

Ps. Will I have any problem welding 6.36mm aluminium flatbar with a proper Tig/Mig welder?