Trying for 12 mpg on a MoHo

[frankiejoe]

Originally Posted by RoadWarrior

That's the 3 1/2 inch at the back rise plus the assumed 1/4 inch spacing. That should allow "full coverage" still where the air tumbling off the leading edge of the first strip in the group just misses the trailing edge of the last strip in the previous group.



3 strips were considered optimum when used on sailplanes in the '70s, to promote a strong turbulation effect, most of the air gets "pumped" three times into nice tight and small energetic vortices. I guess the additional momentum transfered by the fourth and fifth strips had negligible further effects. I guess it's kind of redundant anyway to go with the extras. Sizing is a question of scale of the vehicle, on a longer, taller semi-trailer for instance you'd probably need 1/2 inch x 18 inch devices to perturb the boundary layer enough. On minivans and SUVs 1/4 x 6 inch devices would be adequate. Personally I'd go with the 12in length if you can only find 1/4 high strip and 8 inch if you can find the 3/8 high. It is kind of educated guesswork on my part, I've run the actual numbers before, and got a feel for the ranges, but don't have the books available at the moment to run them for the precise dimensions of your vehicle. But stuff like this you can be 25% off either way and get 90% of the results.

ROAD WARRIOR you are brilliant! I got up to 11.5 at 65 MPH on level ground. Didn't do squat up in the mountains but had some other problems with the MH so sorry for the delay in posting my results. The main thing we were all in awe of is great big semis were passing us constantly and we did not even know they were there! The proof this experiment worked was that every time we were stopped on the side of the road, trucks would pass and we were jostled around like an earthquake. But as long as we were moving, no upset whatsoever! I have extolled the virtues of your genius to everyone who wondered about the dirty strips of weather stripping on the back of our rig. Thank you is not enough so THANK YOU! THANK YOU! THANK YOU!

Frankiejoe