Canopy = better fuel economy???

I had a thought the other day, probably a bit far fetched, but you never know till you ask...

Has anyone experienced measurably better fuel economy by fitting a canopy to their vehicle? I'm going to assume it would improve the aerodynamics of the vehicle (assuming it follows the lines of the bodywork fairly closely.) so if the aerodynamic improvements are greater than the detriment of the added weight, then it can only improve the fuel economy, right?

IT would depend on what it was being compared to. An uncovered tray then most defentalaty as it would be more aerodynamic. But I would assume fuel economy would be fairly equal to a tourno cover, if anything a little worse of due to the extra weight.

Mythbusters tested the theory of tailgate up vs tailgate down, and tailgate up is more aerodynamic as it 'apparently' traps a pocket of air in the tray which acts to smooth the bluff body effect of the cab.

It's probably immeasurably close, you're comparing the pressure drag of the bluff body of the cab from the door handles up, plus the bluff body of the tray back, vs the two combined in the canopy scenario. I'm going to hazard a guess that without a canopy is more aerodynamic, but I'd be unsurprised to find I'm wrong.

Not sure what would be the case.

In my club motorsport experience when people were competing in Austin Healey Sprites at high speed tracks I have seen people when the competition is close at the end of the day, send someone to distract the other driver for a couple of minutes while they put the roof up just before going out on the track, leaving the other driver without time to do it. Apparently it was worth up to a couple of miles an hour on the front straight. I know that is covering the rough equivalent of an open tray, but being much smaller it would be reasonably well covered in the lee of the windscreen as the cabin in a sprite is pretty small.

I have wondered myself if a canopy would come out pretty neutral drag wise. I do know that you can hear the difference between having the bed covered or open. In the end cost and visibilty have kept me from doing it, last ute I had with a canopy was deadly in traffic, anything in the lane next to you that was level with the tray was utterly invisible no matter how hard you looked (That was in a Rodeo 4WD but it was an early 2000's model and had flat mirrors, the Nav with a pair of convex ones would be better) That canopy had the windows start well above the sides of the tray so you lost a lot of visibility, particularly at the rear where cars would dissapear completely. Plus the windows of the canopy were tinted for security which made it even worse in the dark.

Can't say I've noticed any significant differences since adding my canopy but then I've also not conducted Mythbuster type tests.

My canopy (according to the shipping certificate that was stuck on it) weighs about 180kg and since putting the canopy on it I've probably added another 100 odd kgs of permanent weight in the back so going but that alone any positive aspects of adding a canopy would have to be pretty damn good to counter the extra weight.

I'd say it depends on which canopy you have.
I've got a high roof ARB version.
It prob uses slightly more fuel than it did with just an open tray. (~0.3l/100km)

Like Pro-Nav I think it would be negligable. The extra weight of the canopy would have more of a negative impact on the economy than the shape.

Yeah I agree with Jason, I don't measure my fuel economy that well, but i certainly didn't notice any difference.

I think the added weight will use more fuel than improved aero.

My mate and I have measured fuel economy in our D22 TD Navaras. His without a canopy and mine with. There was no real difference in fuel economy.

In the greater scheme of things (being a flying model aircraft builder/pilot and knowing a little about finicky aerodynamics) the difference will be very negligible. A hard tonneau cover will probably be better (the soft one will flex and disturb the air passage over the surface creating turbulence = drag).

Given that this thing isn't travelling at Mach 1 or better, the actual real-world difference might be measurable over tens of thousands of kilometres but it's going to come down to a very small amount each time you fill.

For me, the difference is in storage capacity and convenience. I can fit my 60 litre Engel in the back with the canopy. I couldn't do that with either cover.

Although, I tell ya what, if someone can prove that small gains in aerodynamics can make a large difference in fuel savings, I'm going to take to my door handles with a grinder and make 'em flush like the Subaru Vortex.

KraftyPg said:

My canopy (according to the shipping certificate that was stuck on it) weighs about 180kg

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Wow.

My canopy is light enough to carry on my back, is yours made of lead?

Pro-Nav2.7TDi said:

Wow.

My canopy is light enough to carry on my back, is yours made of lead?

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No just made properly

The majority of the weight in mine is probably in the glass. Each window is tempered glass (2 pieces I think) about 2 inches thick and the locking mechanisms are quite weighty as well, the struts are strong enough that if you take them off the window you can't push them in by hand and in parts the fiberglass is up to an inch thick. It's an awkward 2 person lift because of it's size but weight wise two blokes have no problem putting it on.

2 inch thick glass? WTF? Pope mobile canopy or what? LOL.

Jason said:

2 inch thick glass? WTF? Pope mobile canopy or what? LOL.

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Or he has a pet tiger?

Mine is all steel and weighs approx 150kg. Sagged my original springs up a fair bit, My fuel economy went up noticeably.

08KINGCAB said:

Or he has a pet tiger?

Mine is all steel and weighs approx 150kg. Sagged my original springs up a fair bit, My fuel economy went up noticeably.

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Mine hardly even made a noticeable difference in the springs or the economy but then everyone and every vehicle is different.

I've always wanted a pet tiger but alas just because the canopy has thick glass it wont happen. Even so while nothing is completely unbreakable there is some added assurance (or feelings there of) when the glass is so thick and there is up to $10K of computer gear in the back. The one down side is that because of the height when open and the weight needed on the struts if you don't regularly use all the struts they do get a little heavy when shutting, especially for short people.

The one thing that annoys me a little bit is that the company advertising appears to be between two layers of glass so it can't be removed, thankfully though it's dark writing in between tinted glass which makes it quite hard to read.

so ur canopy glass is 5cm thick krafty?

What brand is it?

I thought it was an Avenger, and their website says nothing about it being suitable for the Pope.

50mm thick glass (2") is extraordinary. Laminated, it would probably be effective even against a round from a Barrett XM107.

Krafty, if you need that sort of protection mate, then I feel sorry for ya. Move to NSW, they only use knives and small calibre stuff up here. Oh, and the occasional crossbow in school playgrounds, but that's only for teens and under. Adults get to play with real live ammo.

I'd love to see a photo of that glass if you could Krafty!