motorhome aerodyamics

[chefdave]

Hi
took photos today but resalution is too high for upload. at the moment according to fuel gauge i have increased mpg by 1-1.5 mpg. when i fill tank again the figure will be more accurate. next job is to order parts for front airdam. also remembering some in past whst saab fitted underneath 900? To aid road holding and drag reduction. think it was along the lines of an airdam in front of rear wheels. basically a v shaped dam with the point of v along centre line of car. wide part of v finished just in front of rear wheels. will need to do more googling on this.

[NachtRitter]

If you happen to have a google account, upload the pics there and then link here.

[slowmover]

And show the percentage fuel economy improvement . . at the high consumption rate of this vehicle type that is where the gains really stand out.

[Frank Lee]

Originally Posted by NachtRitter

If you happen to have a google account, upload the pics there and then link here.

Better yet, use a photo editor such as Photobucket to resize them down to, oh, 700x700 or less, so they don't take an hour to load and for those of us without 6' wide screens, they don't need to "resize".

[chefdave]

Hi
if my maths are correct its about 8% improvment. still more mods to come front airdam and sort out air flow underneath. chassis and underbody are and aerodyamic mess even worse than body shell. if i can get a smooth air flow underneath should see a reasonable improvment in mpg. this will wait until it warms up and wind drops probably next spring. so will have lots of time to plan and gather material etc etc ready for installtion

[chefdave]

Hi
have sorted out a mk 1 version of airdam. dosent look to bad. altered slope of grill cover. when passenger wiper fell off at 50mph it just sat on bonnet and never moved. leads me to think there is now an area of static air in front of windscreen. done some temperory wheel arch covers and fitted wheel trims to rear wheels. also altered maf spring to lean out a factory set very rich fuel mix. cannot give an accurate mpg due to coil wire playing up and servre weather conditions. last week 143mph winds now chill factor is diwn to -10c. so cannot replicate journeys with any consistency. what i can tell is my dolphin is a lot less twitcy in a cross wind. even if mpg does not improve the whole driving experirnce is more pleasent.

[freebeard]

To aid road holding and drag reduction. think it was along the lines of an airdam in front of rear wheels. basically a v shaped dam with the point of v along centre line of car. wide part of v finished just in front of rear wheels. will need to do more googling on this.

So what did you find out? It sounds like a bad idea to me. Two V's in front of and/or behind only the tires would be a wheel spat, which would be helpful. Including the area between the tires would trip up the airflow exiting the underbody. Of course unless you have a bellypan it's probably a mess anyway.

last week 143mph winds

[chefdave]

Hi
still cannot find anything on google but sure it was a saab 99. Will delve into old car mags an article writtern by performance car magazine in mid 80's
Yes 143mph winds. check scottish weather for far north of scotland (orkney islands) been told we have 2 weeks of 90mph winds. dolphin is less wandering but lean with wind is a strange feeling. need to get rid of air con unit (all 40kg) to help with lean.

[renault_megane_dci]

I would love some pics.

[aerohead]

Originally Posted by chefdave

Hi
still cannot find anything on google but sure it was a saab 99. Will delve into old car mags an article writtern by performance car magazine in mid 80's
Yes 143mph winds. check scottish weather for far north of scotland (orkney islands) been told we have 2 weeks of 90mph winds. dolphin is less wandering but lean with wind is a strange feeling. need to get rid of air con unit (all 40kg) to help with lean.

It might be the 900.I spent some time on my back at a Dallas SAAB showroom in the early 1980s looking at all the plastic bits of the 900's underside.It did have some V-shaped components.
I felt as if these were all for splash and spray control rather than drag reduction.Don't know,and as far as I can tell,nothing was ever published about it.