Add air dam to my RV?

[aerohead]

If you can't modify the square edges,is there something like a bicycle rack which could attach to the doors themselves,which a fairing could then attach to.
Those square edges would produce Cd 0.92 if they were all around the periphery.With everything softened,around Cd 0.51.The lowered airdam would knock that down a bit.

[slowmover]

Head over to HENDERSONS LINEUP to see if KONI FSD shock absorbers and FF or RR anti-roll bars and track bars are available. Mohos are terrible about having steering wander. Correction of this will save more fuel than any single aero change (save a boat-tail).

Proper weighing to get tire presssure ideal is also necessary, See the BridGESTONE .PDF on how to weigh an RV. It comes to individual weights for each wheel/tire. The RV Safety Foundation also has info. Weigh with full fresh water, full propane and all gear aboard for long trip plus weight for pax. CAT Scale, nationwide.

At WOODALLS are plenty of discussions on getting Class C mohos to ride and track better than from factory. While the Chevrolet may be better than the Fords there is no room for slop. Work the mechanical baseline (as in alignments specs that may be a hair different than what is present, for example) to start from acquired numbers. Axle weights are good, tire weights are best. Pressure is then set from there. Best shocks and chassis/suspension changes can make a HUGE difference. A rested driver makes a more skilfull driver as the day goes on. I;ve wresteled mohos staring 40 years ago, and have to drive worn 18-wheelers. There is no substitute for a "tight" driver.

That, and trip planning. One already knows the likely range for a tank of fuel. Choose the fuel stop in directon of travel and close to highway entrance ramp, for example. The number of acceleration and deceleration events is key, here. Stops and turns are contraindicated. Plan this ahead of time. Etc. The moho gone through and tires at best pressure plus some planning will take a huge bite out of the fuel bill. Top speed of 58-62 mph as well. If you can learn what the average speed is, then you'll understand that a high travel speed is really counterproductive when it involves lane changes and extended accelerations. Doesn't same time, my friend.

Keep good records. All gallons and all miles. "Success" is a percentage improvement to the annual average. The number itself is not so important.

http://forums.woodalls.com/index.cfm...pging/1/page/1

http://forums.woodalls.com/index.cfm...g/1/page/1.cfm

http://www.hendersonslineup.com/

AN OBD-II reader such as ULTRAGUAGE is also recommended. THe time you actually spend at travel speed is not as great as you may think. THe transitions are what count.

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[Snowman9000]

[quote] Top picture, the Chevy chassis, is exactly what you have? Looks like there is already a pretty good airdam there.

What was the old motorhome? What are the two engines and transmissions? You should plug both of them into the Aerodynamic & rolling resistance, power & fuel consumption calculator, in the Tools section, and see if the differences agree with your observed MPG. You could then tweak your current setup in the tool and see what gains you can make. [\quote]

Yes, the Chevy. There is just a short rubber flap there now. I measured things today. The bottom of the bumper is 14" off the ground. The front crossmember is 8.5" off. There are plenty of mounting holes in the bottom of the bumper. But I'd need something 6" tall, plus a mounting flange or a piece of aluminum angle or something like that. A 6" dam would not scrape on 15º grades.

My old motorhome was what is called a B+, rather than a Class C like my current one. The B+ does not have a sleeping bunk over the cab. Instead it has a slimmer, much more aero protruding cap up there. Both have 6.0L gas engines. The older one had a 5 speed with one OD. This one has a 6 speed with 2 OD ratios. I think if the older one had had a 6 speed, it would have done real well. It was closer to the ground, and lower in height than my new one.

Old one looked like this (not mine):

[Hersbird]

The frontal area on the old one was much less and look at the radius on the front sides of the box of the old compared to the flat sides of the new.
I bet that old one would have performed just as well as the new one with just a 5.3 and the lighter duty transmission as the new one does with the 6.0. If you are really getting over 10 mpg with that new one at 65 I would be pretty happy, I bet there are lots of folks getting 8 or less with that rig.

[Snowman9000]

For whatever reason, the Chevys get better than the Fords. I am fanatic about checking my mileage, and trying to drive economically. Not hyper-miling, just basic things. On long days I do like to drive 65, though.

[Snowman9000]

In seeing the various materials people have used for air dams, spats, using stuff that needed to be reinforced, have you considered sheet ABS:

ABS Plastic Sheet Textured General Purpose Haircell Finish

This stuff is rigid but not brittle, and very impact resistant. With some practice and the right kind of flat solid tip stuck onto a propane torch, you can weld it. I cut and welded an airbox for a snowmobile engine swap one time. And I have no special skills. If I proceed with an air dam and any other spats, I'll use this stuff.

You see car and light truck mud flaps made out of it all the time.

That's just the first source for it I found. I now see Grainger can ship it to their stores, 1/8" thick, 12x48" for $12.64.
http://www.grainger.com/product/Shee...PPD&pbi=1ZBT4#

[Xist]

This is my air dam: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I bought 2 x 24"x48"x1/16" ABS PLASTIC SHEET CUSTOM STEREO TEXTURED FRONT SMOOTH BACK: Amazon.com: Industrial & Scientific, but I still have not decided what to do with them. I wanted to see how they would work for wheel skirts, but want to finish other projects first.

[Snowman9000]

Xist, being rolled up, that stuff looks too flexible? No?