Rooftop A/C Aerodymanics?

[melissab]

I was just wondering....the main purpose for the rounded shape of the Eggs is for less wind resistance etc. So what happens when a rooftop A/C is shoved up there? Doesnt that cancel out the aerodynamics? When a tow vehicle is on the smaller end of the scale wouldnt you want the least amount of drag possible? Will Scamp still install a closet A/C if a customer requests it? I know one could be ordered without A/C and then either use the window method or closet install but for folks w/o the skills/tools etc it would be nice to order one with the preferred installed location. Or is this really a non-issue?

[RSchleder]

IMHO, don't mess with A/C in closets, windows, etc. Have Scamp install the roof top A/C which will cool very efficiently and the drag while towing will be negligible. In other words, a disadvantage such as a slight towing drag is minimal compared to the advantage of having a roof top A/C.

[melissab]

Thanks, Ron. Would you mind elaborating on the advantages?

Originally Posted by RSchleder

IMHO, don't mess with A/C in closets, windows, etc. Have Scamp install the roof top A/C which will cool very efficiently and the drag while towing will be negligible. In other words, a disadvantage such as a slight towing drag is minimal compared to the advantage of having a roof top A/C.

[Frederick L. Simson]

Originally Posted by melissab

So what happens when a rooftop A/C is shoved up there? Doesnt that cancel out the aerodynamics?

Most rooftop Air Conditioners have covers that are also contoured, because the A/C manufacturers are aware of the drag issue. A window or closet installation is really a compromise, most often because of aftermarket installation.

The main advantage I see is working around thermodynamics to circulate the cooled air. This means that the best location for an A/C unit is on the roof, while the best location for a furnace is on the floor.

The obvious advantage over a window installation is loss of window viewing function, AND added drag for components outside the shell of the trailer.

[melissab]

Thanks! I did not plan on keeping a window unit installed during travel (so no drag there) but really dont want to go that route since we live in FL and the A/C is pretty much used full time. That means when it's just me and the kids I'd be hoisting that thing in and out of the window and trying to secure it by myself. Can you elaborate on the negatives of the closet install Scamp used to do where there was no protrusion to the outside shell? You lost me when you mentioned "Thermodynamics", lol.

[Raya]

Originally Posted by melissab

I was just wondering....the main purpose for the rounded shape of the Eggs is for less wind resistance etc.

Not that this has a direct bearing on your question, but I don't think the main purpose of the eggs' rounded shape is for less wind resistance. Actually, more aerodynamic shape would be something like a teardrop (or an airplane wing). That is, largest and rounded at the front, and tapering down to a thin area at the back.

My guess as to why the eggs are rounded has to do with fiberglass molding and properties. It's harder to get the glass to conform to square corners in the mold, and large flat panels with more squared off corners are harder to support and to keep from cracking in certain places. Also, there are considerations for mold shape and releasing the part from the mold or vice versa.

The Boler was originally conceived of by a fellow who had a business making fiberglass septic tanks, as I understand it, and I think these were shipped nested in two halves, so the shape was handy for that. Not that the Boler is the exact same shape, but some of the origins and reasons are common, I believe.

Of course the rounded corners are better for towing than big square ones would be, and a roof mounted A/C will have some negative effect in creating drag; but on the other hand, you won't be wrecking some master plan of aerodynamics that the egg designers had going.

Raya

[Frederick L. Simson]

Originally Posted by melissab

Can you elaborate on the negatives of the closet install Scamp used to do where there was no protrusion to the outside shell?

Actually, I'll have to relinquish the Thread to someone else who is more intimate with Scamp. I wasn't aware that Scamp did closet installs of A/C units in the factory; I thought all closet installations in Scamps were after-market.

Casita used to do closet A/C installations in the factory in their 16' and 17' trailers.
Escape did factory A/C installations in the cabinet above the refrigerator in their 17'

[Pam Garlow]

Unfortunately, not all eggs can have a rooftop installation without reinforcing for the added weight of the AC on the rooftop. And of course, a rooftop AC pretty much eliminates getting the egg into a garage through standard height garage doors.

[Lee Senn]

Frederick As I remember the Scamp A/C was installed under the closet. There was a hole cut in the body and it mounted like a window cooler. A canvas cover would be snapped over it for travel. I suspect there were problems with this type inslallation leakig and that is perhaps the reason that type of installation was elimanated. Lee

[melissab]

Thanks for all the input. Glad to know a rooftop A/C doesnt totally cancel out the benefits of the egg shape when towing.

[mcbrew]

Melissa, here is a list I was thinking about myself as we were considering a new Scamp. We ended up with a used Scamp, so it really did not apply... but here it is, anyway:

Benefits of roof air: Simple, pre-installed, no thought required, more aesthetically pleasing.

Benefits of window air: Much cheaper (about 1/8th the cost), much lighter, weight is low in the camper when traveling, condensate drips outside instead of down the sides, can easily and cheaply be replaced, some are remote controlled and have a digital thermostat, some have on/off timers, can be easily and cheaply replaced, less wind resistance, lower overall camper height, no loss of headroom inside, closer to ideal BTU level for the size of the camper, can take it when you need it and leave it at home when you don't.

Our '84 does not have roof air, nor the necessary reinforcements. I am glad that we are going with a window air unit (not until next year, unless I find a killer deal). I will have to make a frame for it to sit in, but that doesn't bother me. We are going to use it in the back sliding window. There are a number of 5,000 BTU units that will fit in that space. I happen to have a 6,000 BTU window unit -- new in the box -- but it is slightly too wide.

[Ray N]

I remember when, many years ago, I used a car-top luggage carrier - I was shocked by how much it adversely affected my gas mileage. Of course, it was larger than an AC unit and I usually traveled at about 70+ mph, so the effect was much worse than an AC would be.

BTW, EggCamper also uses built-in AC units.

[Bruce Thomas]

I doubt you could measure the difference with or without an AC unit up there, and if you could you'ld probably negate in minutes leaving the tv running while hopping in a store or something. Bruce