Aerolid, new truck and trailering

[Slippery]

Hey all,
I just came across this web site last night. I'm really enjoying all of the design ideas, and the fact that people are this interested in better fuel economy. Thanks to everybody for their contributions.

I'm in the market for a new truck, and I'm trying to determine how to get better mileage. I'm also trying to make a decision on gas vs.diesel. It seems like manufacturers numbers are going up on gas trucks, and with the cost of diesel fuel going up, it might make sense to go with gas. I'd also like to start running biodiesel to help with the environment. I commute about 60 miles a day for work, and drive from California to Idaho 2-3 time a year for vacation. Some aero mods would save me a lot of money.

I'm definitely interested in an Aerolid when they're on the market, and I'll keep my eye out for one here. It's funny because I was talking to a service manager at the local GMC dealer, and he was talking about the benefits of wheel covers and front air dams on big rigs, and I was talking about making wheel housing skirts like they had in the late 60's. It's nice to know that it actually makes sense.

One thing I read, and I think it was written by Aerohead ,was that by trailering an aero designed trailer it would benefit the fuel economy of the truck.. I've read here that having a squared off end to the truck with a regular camper shell is definitely worse for Cd. If I were to tow an Airstream trailer with the rounded front, behind a truck with a camper shell, how close to the back of the truck would the trailer have to be in order to benefit the Cd? Would it create a bubble of air like what is known for in an open truck bed? I think I'd also need to change the design of the back of the trailer to a tapered off design.

Once I get the truck, I'll post some pics, and start posting my mileage logs

Thanks,

Don

[bondo]

There are alot of good people on this site with invaluable information. You will learn alot as I have from them. Aerohead is the supreme maven here and a great guy to boot.

I am finally, finally, finally, finally going to get issued a Patent for the Aerolid. This has been a long, hard and expensive endeavor but it will give me the leverage needed to court manufacturing companies and capital. Again, finally!

Let me know what type of truck you purchase. I feel 2012 is going to be a very good year indeed. I hope it is a great year for us all.

Merry Christmas to all,

Bondo

[slowmover]

If I were to tow an Airstream trailer with the rounded front, behind a truck with a camper shell, how close to the back of the truck would the trailer have to be in order to benefit the Cd?

Welcome

The big truck manufacturers want to see no more than about 24" between tractor and trailer for FE. On my TV/TT rig the gap is 60". On some nicely done custom hitch rigging jobs (all of these are aluminum aero TT's) the gap can be down to 42". IOW, treat the TV and TT separately for aero. No wing or funky bed topper will benefit the "gap" effectively. The gap has to be shorter.

Conversely, some 5'ers can have a nice short gap. See posts by Kamper Bob and Skyking. The other trade-offs of a 5'er don't make it a worthwhile choice past a certain size, IMO.

As to the rest, you'll want to define the life and the miles expected of the truck. Without that it's pocket pool. Will the truck have IRS deductible miles? Will it earn it's way, IOW? Or is it an expensive commuter vehicle, worthless 4WD and the rest? Because there are some alternate TV's that can pull even a big A/S TT that are also far better when solo for safety, FE and general comfort.

I compared my truck to another man in the same climate/terrain as mine driving an exact replica of mine but with a gas motor with the same miles solo & towing, plus roughly city versus highway. So long as diesel was no more than 50-cents/gl higher than gas then the fuel price difference was irrelevant. But that is only part of the story. At 8-years and 180k miles I am about halfway through the life of my truck. With under $400 in repairs, and a maintenance schedule better than the gasser. Two sets of tires and brakes in the first quarter million miles is how it is looking. Conversely, a gas motor truck is nearing end of engine design life, [B50] at the same point in time.

IOW, initial purchase price can be more than offset by miles/time. MPG is just icing on the cake.

State your definitions of use plus life time/miles more clearly. Miles solo, miles towing, etc.

.

[aerohead]

Don,I'm worthless to you right now.I've been grinding trailer numbers for months now and I hope I live long enough to share something productive.
There are very few prediction tools for towed vehicle aerodynamics/mpg.
If you can get a hold of one of Hucho's books on road vehicle aerodynamics,he has a brief section on car/trailer aero.You'll also want to look at commercial vehicle aero and the section on NASCAR drafting.
Your aerodynamics will be governed by the frontal area of the trailer.
As you know,gaps cost us,and it's only recently that folks are actually 'looking' at the back of the rig.
Dig in and read all you can.I hope to have something to share sooner than later.Welcome aboard!

[Frank Lee]

If I'm not mistaken he's talking about buying a truck for commuting.

If I am, then carry on!

[drewb0y]

Originally Posted by bondo

I am finally, finally, finally, finally going to get issued a Patent for the Aerolid. This has been a long, hard and expensive endeavor but it will give me the leverage needed to court manufacturing companies and capital. Again, finally!

Not sure if you ever figured out funding for your aerolid, but there's a site out there called kickstarter, at kickstarter.com where you can describe your project, name a unit price and how much you need to begin production, then people submit money for it.

Kind of like open source venture capital. Worth checking out anyway.

[slowmover]

or funky bed topper

Bad choice of words on my part. I distinctly want an Aerolid, but I was referring to the higher-than-cab toppers I've seen suggested on quite a few forums as folks think that they serve an aero purpose when towing a trailer.

A TV with a "clean" exit will make any improvements to the trailer easier to identify I would think.

Now, as to TT's, note on this trailer the hidden propane tanks, and the battery box suspended between the A-frame rails:

1995 Sterling

As compared to this earlier model where both are dirtying up the entry:

1975 Silver Streak

TT configuration is often not amenable to change. But I would think that an AEROLID on the TV, and a cleaned up TT frontal area would be of benefit.

Enclosing the TT A-frame with a smooth transition to a TT with a sealed bottom would also be slick.

I have been looking at alternate rear bumpers on TT's for my next one. The stock piece is a big ol' cow catcher in height and width. Extends past the edges on both sides (and is strong, have seen another vehicle nearly totalled after hitting a moving trailer at the rear bumper), but is like a sail:

Silver Streak rear bumper

Where a bumper of round shape serves the same purpose, but with some "benefit" (and where the rear frame rails, again, could be enclosed. Depending on the trailer and the contemplated solar power battery bank for a non-Airstream aero aluminum trailer, a couple more batteries could be fitted between the rails given some calcs about adverse handling potentials):

1972 AVION rear bumper



.

[KamperBob]

Inserting pix for convenience.

Originally Posted by slowmover

or funky bed topper

Bad choice of words on my part. I distinctly want an Aerolid, but I was referring to the higher-than-cab toppers I've seen suggested on quite a few forums as folks think that they serve an aero purpose when towing a trailer.

A TV with a "clean" exit will make any improvements to the trailer easier to identify I would think.

Now, as to TT's, note on this trailer the hidden propane tanks, and the battery box suspended between the A-frame rails:



As compared to this earlier model where both are dirtying up the entry:



TT configuration is often not amenable to change. But I would think that an AEROLID on the TV, and a cleaned up TT frontal area would be of benefit.

Enclosing the TT A-frame with a smooth transition to a TT with a sealed bottom would also be slick.

It seems to me the older style protruding LP tanks would help fill the gap between tug and trailer, reducing lee side turbulence. I presume the lead face of the trailer is well within one width of the tug and thus [the tanks are] not much of a player in straight on dynamics. Am I misunderstanding this post?

[slowmover]

With a 60" gap between TV and TT I am working from the assumption that, for aero purposes, one may as well run the vehicles side-by-side down the highway; that aero for each vehicle should be treated separately. Even with a more conventional hitch, one is still at nearly that length.

My "thinking" if that's what it is, was more along the line of extending the sealed bottom of the trailer out to its' maximum. Flip the trailer over visually and cover the frame extension gaps front and rear. A simple enough change.

A better set of pictures if I had them would illustrate what I "think" I was saying. That is, I think that the gap is better served by some other set of devices or aero aids if the battery box and propane tanks are mounted in the later year model configuration.

I walked outside to check dimensions. On a 1976 SS the hitch ball center to trailer wall front is 39". The propane tanks are 24" from the trailer wall front, with the battery boxes behind it.

Your point, KB, is well-taken that one could build that structure around the two in order to enhance frontal area flow (if I have stated that correctly). I used to have a picture of where this was done on a late 1960's Avion by an owner. I don't see these components as "filling" the gap, however, as something more extensive would be called for I would think. We'd be passing from the idea of separate vehicles, to a combined rig (as it is in fact), but we are waaay beyond the big truck ideal gap of around 24".

Let's use the example of a big winch on a bumper mounted two feet in advance of a pickup truck front bumper. One could enclose it as much as possible, but a winch mounted inside of and behind the dimensions of the stock bumper would be better overall I'd think.

I don't think there will be great deal of difference between hidden and open mounts. But any other changes, to either vehicle, might show up more easily.

That post above was more in line with what I'm thinking an Aerolid could do for my rig. If I am able to purchase a late model SS (through 1997) then a bit of cleanup (sealed frame extensions) might be about as good as I can take it short of really extensive work (nearly or fully sealed TV-TT gap; boat-tail, etc).

If my initial assumption is off, then . . . .


Edit: I haven't gone to the trouble of seeing what, if any, Aerolid extension might could work and not interfere with the WDH apparatus on a tow rig; thinking of the tailgate mounted "box" shown on a recent Aerolid post. Probably an add-on to the upper surface extending past the tailgate might be it.

The problem with any of this is the low annual miles of use for most RV's. If we take 5k annually as average, then one must keep the rig a very long time for any FE benefits to show. So also, changes that inhibit maintenance access become a problem. Etc.

.