DIY roof rack for Discovery 2

[MLu]

Let me start off with saying that I now understand why most roof racks are made out of tubes, not square stuff. This is less of a build thread and more of a practical lesson in aerodynamics.

A bit of background; I decided to try and see if I could modify my Thule roof bars to be a bit more all-round usable and more roof rack like, while still leaving the ability to carry various home renovation related things on there. Long pieces of wood and the like. Working in our apartment building's garage limits my ability to do... well, anything other than the odd hole or cut. No fabrication, no welding. Bolts and nyloc-nuts is what we're going for.

I figured some aluminium L-profile bars would be just the ticket to get a base to work from. From there, the plan is to attach some more bars in between, maybe some sand ladder holders and places for a shovel and a couple of pelican cases.

Said and done - an absolutely never-ending amount of measuring and fitting and fiddling around later, and I have some 4x4 cm L-shape aluminium for sides, and 3x3 cm for the front and back. It feels really sturdy. Not walk-on-it sturdy, but sturdy enough that any weight I'm comfortable with carrying on the roof will have no problem. To get the load to spread evenly between the Thule bars and the first and last L-shaped piece, I figure to invert the front and rear piece. That turned out to be a mistake.






(All pictures are before turning the front bar over, but you can figure it out)

The front bar sounded like a helicopter taking off when driving about 75 km/h and up. Didn't shake and rattle one bit, it just created an enormous noise and an equally enormous wind resistance. The Disco has the aerodynamic features of a brick, but with this thing on it felt like I was towing a parachute. Lesson learned. I took the front piece off and turned it around so that it's now a regular box shape in the front. Still makes a bit of noise, but it no longer feels like a parachute. However; it wobbles and shakes in a really bad way.

As you may or may not see from the pictures, the front bar is almost 30cm above the roof, and roughly at the front edge of the sunroof. My theory, based on absolutely no understanding of aerodynamics (if I had that, I probably wouldn't be driving a Land Rover), is that the air being pushed up by the windscreen hits the front bar and causes the wobble.

Next plan is to try moving it back a bit towards the front Thule bar and see what that does. Anyone else with similar experiences from trying to cook up a roof rack?

EDIT: Yup, that was exactly what it was. Moving the front piece back a bit takes it out of the airstream coming over the bonnet and up the windshield.

 

[MLu]

Right... time for the next step in this project that advances at a pace that varies wildly from a slow crawl to positively glacial; flooring.

Weatherproof plywood is heavy, and because I've designed the frame like a monkey, the spans that it needs to.. span are a bit wide. Just supporting the weight of the plywood itself means it needs to be thick and heavy, never mind with any kind of load, and forget stepping on it. So; I've had a pair of waffleboards laying around for a while, which I've never gotten around to actually use for anything. After fiddling with them for a while, I decided to just bolt them to the load bars and the aluminium. There's a bolt and a nut sticking up from the load bar, the waffleboards are placed on top of them, and secured with a large washer and a hand-tightened eyelet-thing (in lieu of a wingnut). Good enough to stand on. Heavy as all hell, but at least they theoretically serve a dual or triple purpose as flooring on or off the rack, and traction aids / bridges.







The keen-eyed reader will have noticed that so far the fancy aluminium does nothing except add weight and catch the wind, so the next step is to add a bit more light-weight flooring, think of some sort of way to store a couple of pelican cases (pictured in close-up above), maybe a jerry can and just possibly some sort of seriously, seriously ghetto think-two-pieces-of-conduit-and-a-tarp awning. I also need to go and actually drive this thing somewhere.

 

[MLu]

So we went off for a few days, a couple of countries and a couple of thousand kilometers and we never really did anything with the roof rack, except listen to it make sort of a whining sound at about 60-70 km/h and a general whooshing sound above that. Ok, once we almost took down the sand ladders to negotiate a small stream on a beach, but ended up tearing up the front bumper instead.

The middle part of the rack is quite simply a 9 mm marine plywood sheet that fits between the green tracmat-things. It's supported from underneath by a couple of sturdy (something like 3x6cm) lengths of wood that are screwed through from above. The whole thing got REALLY sturdy all of a sudden.



I've been driving around with my 10$ folding chairs on my rack, looking expo-as-******k, and the experience has taught me that there's no way I'm putting any more height on this thing for daily use. Going into parking garages is starting to be a bit nervous... with just the rack, 2,1 meter garages are borderline, but with the chairs on top (which add maybe 10-15 cm max) I'm dodging (or hitting) light fixtures and low-hanging signs. I'd love some sort of rails on the rack because frankly the aluminium is not ideal for tying stuff to, but not real hot on the idea of more height.

On that note, my solution for getting an additional 100-200 km of range is a 20 liter jerry can mounted to the ladder, rather than to the roof. Yes, I know more weight on the door is bad, but realistically it won't be filled very often, and when empty it's negligible. It' simply a generic jerry can holder that sits on the lowest rung of the ladder and is held in with a couple of wingnuts for easy removal to a piece of aluminum that is in turn bolted to the ladder frame. Strapped in to stop vibration and as an extra precaution.



Next steps are to fiddle about with the lights, move them up a bit to get a more usable are of illumination, and make the wiring a bit more civilized, and I've been eyeing the various DIY-awning projects...