Moon Caps - Any Value on 1st gen. Honda Insight? (A-B-A coastdown test)
 

I've acquired a set of moon caps that fit my Insight, but I'm suspicious that they have any value aerodynamically over the stock alloy Honda wheel. Impossible to test on an Insight. Any opinions?

I think you won't notice any gain, because Insight wheels are pretty smooth already. You may try to measure that but you'll add some weight to the wheels so it will affect your FE too but in other direction.

I'd say it'll help overall, but we're talking tiny fractions now, not worth the effort. MetroMPG just did some tuft testing with his insight and the tire area and the flow is pretty darn good around the area.

http://ecomodder.com/forum/showthrea...eel-23529.html

Wonder if they will fit the alloy wheels of an Insight 2?:thumbup:

I wish I'd planned a bit further ahead when I did the tuft test video - I would have stuck on a smooth wheel cover to see what effect, if any, it would have had on the tufts.

As the others have said, I think the gains would be very small.

That said, if I had a set, I'd absolutely put them on.

Yes that would have been nice, BUT I can't imagine the tufts would have been any better with moon caps. The original wheels are so smooth that improvement if any is gonna be really small.

I just got a good buy on a used set so thought I'd grab them:)

I don't think the OEM wheels are that smooth.

They're better than average, sure. But they're full of holes, little spokes between the holes, and those 3 styling "indents".

Well somewhere between your opinion and mine, there is a real answer;)

I just don't know how to get at the answer, since the difference is probably very small and nearly impossible to separate from the noise, given the difficulty of testing on an Insight.

What would you suggest? I suppose that one could do some high speed coast down test from say 70MPH to 50MPH. That would eliminate many of the Insight specific variables that confuse Insight testing. What you think of that approach?

BTW, the Moons protrude more into the airstream than the rather flat stock wheels, so there is that arguement against them. If this protrusion were productive, then Honda could easily have done the same thing with an alloy wheel. I'm just kinda suspicious that flat is better with the other work that Honda did around the fender well.

Your thought welcome:)

I agree the potential for improvement is probably tiny - likely too small to show up above the noise in coastdown testing.

In this case, I really do think a subjective look via tuft testing might be the best way to make a decision.

There may be other reasons Honda may not have gone with a more convex shape - eg. maybe it would have been too likely to suffer curb damage. Just speculating. We know they didn't completely optimize aerodynamics, so it's fair to be skeptical that a particular design choice is as good as it can be.

Tough to say for sure, other than this question gets pretty close to how much gild to put on the lilly. :)

FYI: I'm sure you've seen other Insights with smooth wheel covers, eg. member mattsmalls did DIY covers with fiberglass:

http://ecomodder.com/forum/attachmen...1&d=1273170953

from: http://ecomodder.com/forum/showthrea...tml#post173457

And I've seen moon type caps on other cars, eg Alfred State's competition (efficiency) Insight:

http://img.photobucket.com/albums/09...insightlow.jpg

from: http://ecomodder.com/forum/showthrea...l-20178-3.html

Add one more to the list:
http://3.bp.blogspot.com/_fHAKRh15ey...0/DSC02000.JPG
G/GT record holder at Bonneville.