Hi, I'm looking to build either a motorhome (RV) or a pop up caravan to be towed by a small 4wd/awd and would like some input on their relative aerodynamic merits.
We go travelling/camping fairly regularly, but I would like to be able to do big trips as we did in 2014 when we spent 6 months travelling around Australia (See
Around Aus | Reflecting on an awesome trip for blog of that trip) with less fuel costs. I'm also interesting in going electric, but that is a side factor and doesn't relate directly to aerodynamics (except that lower Cd is better!).
First option: a motorhome/RV. This option has a higher frontal area (extremely rough estimate is 4.8m2). Be looking to build one on something like this LDV cab chassis (chosen as ICE front wheel drive and considering adding electric to rear axle for one/other/both arrangement).
V80 Cab Chassis Overview - LDV Automotive Australia Total dimensions would end up something like 2.6m high, 2m wide, 7m long. Roof would curve up and then down, and could taper the sides in at the very back - like in very rough sketches below. I've only recently started reading/learning about aerodynamics, but would look to optimise the shape and finer details. GVM (total max weight) is 3500kg. What kind of Cd can I expect - is 0.3 viable/possible for a motorhome like this?
Second option I'm considering is a pop up caravan being towed by something like a Subaru Outback or Forester - relatively small and lightweight for 4WD/AWD and I have lots of experience with them (own an old Forester). The pop top caravan would be custom built by myself (not new to me - have built a small caravan before), and might look vaguely like in the following link, but of width about 2m, height from ground 1.6m and body length of 5-6m.
Eco-Tourer Both tow car and caravan could be optimised for aero, including deflector plates on the back of the car to try and smooth the transition to the caravan. Frontal area somewhere around 3.4 m2. Subaru GVM is around 2000kg, and trailer would be probably 1200kg or so. What kind of Cd could I expect to achieve with this trailer arrangement? Is 0.5 possible? Or should I be expecting a lot more? I haven't seen any figures for large towing situations.
What I'm wanting to determine is which would be the more efficient arrangment in terms of power/energy needed. Allowing for reasonable (not completely over the top) aero improvements for both options. I think one will have a lower Cd, the other a lower frontal area, but I don't really have any idea as to the net result.
There are lots of other issues and practicalities to consider when choosing between a motorhome/RV, or car and caravan, but I want to start by understanding the aero implications. I expect we'll spend a lot of time in this vehicle over the coming decades (hence why not small!), and do a lot of km's. Thanks for any advice.
Any pointers/links to aerodynamic largish motorhomes also appreciated
Motorhome side view:
http://www.aroundaus.com/wp-content/...rhome_side.jpg
Motorhome iso view:
http://www.aroundaus.com/wp-content/...orhome_iso.jpg
Motorhome plan view:
http://www.aroundaus.com/wp-content/...rhome_plan.jpg
Motorhome front view:
http://www.aroundaus.com/wp-content/...home_front.jpg
Subaru and caravan option:
http://www.aroundaus.com/wp-content/...carcaravan.jpg