That video is a watermelon to cumquats' comparison; that dog don't hunt. You're driving your brick, not towing it, big difference. I drive a brick too. If I can save a tenth of a gallon, I'm all in, and I don't care what any uppity mofo says. I'm with you bro!lol
you know that aero on a Brick of the Size of my RV makes a huge difference? When you go from 8 mpg to 10 or 11 mpg , that really has daily application impacts. First - my fuel Tank is 40 Gallon, that is a fixed value. When I add one MPG - that's 40 miles of more driving on the same tank.
First: The range on RVs is terrible and fuel stops really hold you up. Further, the gas station network is already bad in many parts of country and will get worse as electrification gets more popular, many back country roads Gas stations have already closed - and more to follow. So I'm slowly getting the the point of range anxiety with a gasoline power vehicle.
8 mpg 29.4 l/100km 9 mpg 26.1 l/100km 10 mpg 23.5 l/100km 11 mpg 21.4 l/100km
Second:
at this point it didn't cost me any more. Needed to elevate the Panels anyhow to clear the vent - so I just going to try it. Just didn't want to create a hazard.
I've got about half a year of fuel data on the RV without the panels mounted - now I can compare and see if it's better, same or worse.
My Thesis is that at least I'm not creating any significant more drag, with a small glimmer of hope to lift the air above the aerodynamic dirty roof with all the random items up there and reduce it.
A little sheet metal to round things off would help. Look at modern cross country big rigs for inspiration.
I'm going to cover the sharp edges with some flashing so that it will be much smoother.
that should be a easy enough modification. Should be as stable or even better then before. I would try it.
Are you always this condescending? The only helpful suggestion you had was proper tire inflation and type; look how much time you would have saved and come across more friendly.I have enough understanding to know the value of aerodynamics. I ran an aerodynamics testing business. Not for larger vehicles but human powered vehicles. Worked on multiple successful world records. Eeking out every last aero drop matters a lot. I get that.
I love your enthusiasm but frankly, your panels are going to make 2/5th of SFA difference.
If anything the sharp edges they present are probably going to increase your effective coefficient of drag rather than lower it (sharp edges like that are bad aero news) but either way the difference will likely be so small as to not be measurable within the precision of fuel consumption figures. At least not in any controlled manner such that you can make verifiable claims, especially considering the multitude of uncontrollable factors which influence such outcomes. IOW it will be lost in the noise.
You might after a while find your fuel economy improves because of a natural bias with your testing, IOW the very fact you have put them up there consciously or subconsciously results in you making changes to your driving habits. Or the changing engine state of tune, tyre wear, type and pressures, suspension, even seasonal and year to year variations in weather will confound any such assessment. And this assumes the driving locations and conditions net out to be the same.
If you want to save fuel while driving a vehicle of that size, weight and shape, find ways to (safely) lose some vehicle weight (this mostly helps on the inclines) and reduce your driving speed (helps everywhere for fuel economy). Also ensure tyre pressures are appropriate and consider the type of tyres you use and make sure they are aligned correctly and your suspension is in good order. Having a well tuned engine of course, clean air, oil and fuel filters, cooling system working as it should, not operating unnecessary devices to place additional drain on the alternator.
I think the biggest benefit of the panels on your fuel economy will be their utility in charging batteries for a tyre pressure inflation device to check your tyres at least weekly to make sure your rolling resistance remains optimal and your vehicle is as safe as it can be:
RYOBI ONE+ 18V Cordless Dual Function Inflator/Deflator P747 - The Home Depot
RYOBI introduces the 18V ONE+ Dual Function Inflator/Deflator (tool only). This inflator is capable of completing both high pressure and high volume applications. Powered by RYOBI 18V batteries, this unit has maximum portability for any location. Best of all, it is part of the RYOBI ONE+ System...www.homedepot.com
I work in Data Analysis and I'm aware of the various bias and measurements errors you can introduce into a data set.
This is a prototype and I want to see if I get a clear enough signal so that it warrants further investigation.
I didn't post it for a comparison, it just reminded me of an entertaining video.
No, but with help I can lift my game.
Cool. Good luck with it.
Not any more. I'm retired from that business. It was fun though and playing with aero analysis is a good learning. Much of it is counterintuitive.
Indeed. And then they go off and hide the answers they are looking for; why have 58 coefficients all named "C"?
Superb.
Well said, sir! Those boys out there on the highway hauling goods have to squeeze the squeal out of every ounce of fuel to stay profitable. These big trucking companies are serious about limiting drag, taking care of tires, and limiting idle time. Most trucks nowadays have small diesel generators, batteries, and solar panels for the drivers when parked at truck stops for the night, whenever that might be on a 16x8 hour shift. I tried driving for a while when I got out of the oilfields; it's brutal, but if you're willing to go for the miles, you can make 75 to 100k. I left the darn oilfields for the same reason, too many hours working and not enough me time.
This is essentially my concept for attaching as much solar power as practical to the top of a minivan. Sadly, I am not an aerodynamicist, but, I hope that making the bottom of the solar panel array clear the (so far smooth) top of the minivan by 2-3 inches and smoothing it with a cover which creates a plenum above the cover and below the panels, which I might have to drive with fans in some configurations, to keep the panels cool, but hopefully not most (the concept is a tilting array which is only locked down flat when the vehicle is soon to be, is, or just was, in motion) and round edges, except, I guess the trailing edge, will create acceptably low drag.
A point made in the video, and they do it by proper consultation and testing with aerodynamicists using all relevant tools at their disposal, be it CFD, model testing and full scale low speed wind tunnel testing.
Just coming back to the home brew physics in play here, to see a reduction in energy consumption from 8mpg to 9mpg at same speeds is going to require a ~15% reduction in the coefficient of drag (give or take). I could probably narrow that down a bit better with some better numbers on frontal area and likely rolling resistance of the vehicle but it won't be horribly (e.g. an order of magnitude) out.
Offset is the primary goal, if it helps the overall aero - would be cool.
The higher the length to width ratio is with any object moving through a fluid the less resistance it has to moving through that fluid so that makes sense.
www.openfoam.com
Give this a think.
I don't know much about your specific vehicle but I guess I'd want to be sure any such additions are not going to adversely affect the engine cooling system.
Cool. A lowly 1980s ANU physics/maths degree for me.
