A quick Aerodynamics question and Weight study of my DIY camper

[high-and-dry]

John just go away.

I cant believe I am saying this, he will be towing a boat as well as the driving the truck with the camper on top. So he would be limiting his speed any way. You do realize most highways even tractor trailers are doing 70, try driving rte 81 in Virginia, up and down the mountains the truckers are 80-85. At some point doing slower becomes a hazard, and 55 mph in some areas is a hazard.

 

[john61ct]

It was a genuine question.

My point is, even 5mph can make a much bigger MPG difference than minor adjustments to the framing angles.

Yes it is OT but when I am towing a boat trailer (14K# most recently), I have never had any "safety issue" driving more slowly than what other vehicles are doing.

If some are impatient and get frustrated, not my problem.

And of course surface roads usually make for a more varied and pleasant journey anyway.

 

[billiebob]

I will be towing a boat most of the trips, so 55 to 60 mph.

55 is the magic number. There was a reason the double nickel became the National Speed Limit during the 1970s energy crisis.

55MPH became the National USA Speed Limit from 1974 thru 1995 altho there were several exemptions after 1988.

 

[billiebob]

We are so behind the times, 70 years ago when they wanted aerodynamics, they actually built for aerodynamics.



And yes, the rear, drag is more important than the front.



No matter how many angles you use.........



A curve is always better,,,,, GMs Parade of Progress ... 1950 ??
GM built 6 of these, one sold a few years ago for $460K.
Duals on the rear... and Duals on the front steering axle too.

 

[E18]

Wow, thanks for these classic pictures. Really amazed at our GM’s engineers. Ah, it is a lot of fun to learn new things and work on some big projects especially during the pandemic. No commute to work saves a lot of time to think and learn and create. Yes, these questions and considerations seem a bit penny wise and pound foolish sometimes especially when DIY cost is almost as much as buying a new camper build by a professional. The price of these slide in boxes are simply a bit overpriced but the demand is there so who am I to argue. Debating whether to buy or continue my research to build. The up side is I can build it the way I need, but the downside is I may encounter waste due to mistakes and imperfections. Uh, glad I have you guys who is so willing to add your inputs. Thanks again!

 

[high-and-dry]

The really funny thing about the aero designs from the 50 and 60's are most of them where wrong. The designers made what they thought would be nice and slippery thru the air, but they made stuff that had weird results when tested in modern wind tunnels. A modern toyota camary is more aerodynamic that the porsche 944 was.

They did get lucky sometimes, but modern computer testing has found stupid little things that make huge differences. The really weird things like a bike mounted on top of you can doubles the wind resistance of the car. yes the bike has more drag than the whole car. ( depending on the car )

from the article below
"Carrying two mountain bikes on the roof had the biggest impact. The Altima lost 13 mpg, going from 46 mpg down to 33. The RAV4 lost 7 mpg, dropping to 32 mpg from 39 mpg."

How to Get the Best Fuel Economy Now

To help ease the pain at the pump, Consumer Reports offers these test-based tips and techniques for getting the best fuel economy from your car.

www.consumerreports.org

 

[rruff]

Yes, these questions and considerations seem a bit penny wise and pound foolish sometimes especially when DIY cost is almost as much as buying a new camper build by a professional.

80/20 isn't a cost effective for a camper frame, or probably even a structurally sensible (weight vs strength and stiffness, many bolted joints, etc).

Try wood?

What were you thinking for panel construction?

 

[dstefan]

Airtab | Aerodynamic Fuel Savers | Welcome

Airtabs™ are powerful vortex generators that reduce vehicle drag, save fuel, and improve vehicle safety by improving stability and mirror visibility in rain or snow.

www.airtab.com

Aerodynamics Research Revolutionizes Truck Design | NASA Spinoff

spinoff.nasa.gov

I’m pretty likely to use these on the back of my square Ovrlnd Camper due soon. As must for dust as anything, but as a former recumbent bicycle racer, and having tested, built and modified multiple fairings and aero devices, I can say this sort of stuff works. Think about why golf balls have dimples?! Not gonna get you to 20mpg, or even 15, but little aerodynamic improvements can help a lot. Even marginal improvements add up over many miles.

 

[Buddha.]

You save a lot more fuel just slowing down a bit

radical concept I know

I've had a 20+ mph headwind for eight hours straight once, and I was in a hurry to get home. A little aero goes a long way.