motorhome aerodyamics

[renault_megane_dci]

Nice rear wheel covers from a Renault ;-)

[wmjinman]

Originally Posted by chefdave

Rear Spoiler Idea Photo by chefdave42 | Photobucket
hi would this rear spoiler idea work on my dolphin motorhome. am planning to use plastic drain pipe or guttering to form base of spoiler then use gaffer/duct tape to cover up gaps for road testing. would it be better to angle down 12-15 degrees or keep parallel with roof line.
thanks
dave

My 2 cents - - -

Better to angle it down, but probably no more than 12 degrees. While you're at it, if you can do the sides too, same 10 to 12 degree angle, that should help even more. Can't really see the picture too well, but it looks to me like that grey thing would do nothing other than possibly give it a clean separation edge if it was rounded before.

As far as your front end plywood "spoiler" grille block, I did something similar to that on my Jimmy with cardboard, except it was attached directly to the bumper and top of the grille (immediately below the edge of the hood). With your push-bar, my guess is the way you did it was the best, however, closing those gaps at the top and bottom would probably make it better yet.

Also, I had a couple clear pieces of Lexan I put in front of my headlights, too. It looks like you could do the same thing with yours - continue the plywood thing you've got on each side with Lexan (or plexiglass). That would give your front end a more rounded shape, which should help the air move past easier.

[ennored]

You have searched this forum, right?

Aero RV

[freebeard]

Aero RV

A classic. There's also the website search button.

aero RV - Google Search "About 1,770 results (0.27 seconds)"

Too much?

[chefdave]

Yes it is the light grey cornice but was going make so that the edge of spoiler ??? Would be 6-8 inches from rear body work. have seen a few towed caravans with a bigger version of cornice. lots of modern motorhomes and 50 seater coaches have a large spoiler intergrated with their roof's. angle of mine would be slightly down to copy start of boat tail. boat would not be fesiable due to length and large over hang on an already overloaded chassis. bottom line is that astra+addition in photo is suppose to be wind tunnel tested. so thought i would copy a proven idea. none of us can afford a wind tunnel for testing ideas. now i need a car and driver to follow and film tuffs for airflow + a still day in the windest part of europe. nothing is ever easy but if i get a good result then all hard work pays off. sure most ecomodders on here have had alot of trial and error before getting reasults sort which makes it an emormus sucess. still researching ideas to clean up underbody which is a nightmare to try and clean up as need access to stablizer legs water tank draining etc etc. may just got with full length body skirt

[chefdave]

Originally Posted by freebeard

A classic. There's also the website search button.

aero RV - Google Search "About 1,770 results (0.27 seconds)"

Too much?

my biggest problem is over hang at rear. estimate front to rear weight balance is 30% front and 70% rear. chassis was orginally designed for max gross weight of 2-2 1/2 tons. my motorhome weighs 2.8tons unladen have stripped interior of all doors bathroom hand basin shower(does not work). Also in uk this getting towards top end of parking ease and driving on 2 lane roads. have to use 2 parking spaces one behind other to great annonace of other car park users.

[chefdave]

Originally Posted by renault_megane_dci

Nice rear wheel covers from a Renault ;-)

Yes renault wheel trims will fibre glass over holes to make them more moon disc style

[chefdave]

Hi wmjiman
yes was going to get some lexun to fill in head light gap in bull bar.
Gap at top of bull bar is very narrow but will work something out. bottom of plywood is open to allow cooling to rad. works rather to well at moment so when summer?!?? arrives should cope well. thanks again for angle of spoiler will need to do a cardboard mock up. will coroplast be strong enough to cope with air pressure. when i do rear aero mods the furthest i can go to make is a vertical line from rear of square chrome bumper.

[wmjinman]

Anytime you can reduce the airflow through the grille/engine compartment (without engine overheating), it will help. If you can make the bottom part easy to remove, so if it gets too hot in the summer, you can just take it off until next winter, that should be ideal.

I would think coroplast would be enough strength for the parts on the back end. There shouldn't be too much force against it there from driving - not sure about your 90 mph winds!!! If parked in a position where the wind hits it from the rear, there may be a problem if it's not strong enough. Added benefit to the coroplast: keeping the weight down!

[flying kurmaster]

http://ecomodder.com/forum/member-fl...56-640x480.jpg

not sure if I got this picture posted, I haven't been here in a while,but this is what I did to the back of my van, I didn't get any mpg gains, I intend on making it bigger one of these days. I did find an improvement in drivability. If you go to my album and open the Kurbmaster album you can have a look at what I did under it, also no mpg improvements. I had an airdam on it last summer and that gave a bit of improvement but I tore it off when my brakes overheated in a particularly hilly coastal drive, however afterwards I think that was not the reason, so I will be putting it back on as soon as I get a chance. I will also extend the top rear spoiler at the top and taper from the rear lights upwards to meet the extension, likely another 8 inches or so.