Hitched Detachable Boat Tail finished. With tests!

[MetroMPG]

Brucey: what were you using for instrumentation for your ABA test runs?

And did you have the road to yourself - no other traffic ahead of you?

[orange4boy]

Your resolution at mileage that low will make it difficult to see a change. Make sure you check for sticking brakes.


Is there no way to change the angle slightly without a total rebuild? I noticed that a few degrees can make a big difference. Even if your tufts are flat you can be getting a lot of lift induced drag. Your tufts will be flat but dance more if you are close to the edge of separation. It's a hunch I have (an educated one) that induced drag spikes at that point. I have not found the paper that confirms this but from flying aircraft the butt o meter is pretty sure.

[brucey]

Scangauge II, its usually within 1% when I do a tank fill.

And nope, I dont think there was a way to change the angles without a major overhaul of the whole thing. It would be easier to start from scratch more or less.

I've scrapped most of it at this point. Why I love building with screws. You can re use them (: The wood is in my wood pile, the skin is in my metal pile, and the PVC is in my pipe pile. The flat tail piece is left pretty much as is with the cord and all the lights still attached.

I think I've got something else coming up, but I've got christmas on my mind right now.

And yup. Road was all clear. There was maybe 5 cars the entire time.

[thatguitarguy]

Yeah, free is even cheaper than cheap. I don't have a metal pile, but I do have a woodpile, and wood is easy to work with, but I think I'm going to skin with Coroplast. It's a lot lighter than metal.

[MetroMPG]

So you reset the SG's trip average MPG at some marker at the beginning of each run and read the result after another marker?

The reason I asked about other traffic in your lane: if you're in a draft with other traffic, it would have diminished the apparent effectiveness of the boat tail. What made me wonder about this was the 33-34 mpg results on your runs in a car rated for 25 mpg highway.

[brucey]

Never drafted. The only cars were in the opposite lane. It was a quiet night.

I have higher than that reported MPG before. I averaged 34 mpg on a trip to florida recently, no real driving techniques other than keeping the speed down. My lifetime average would be a lot higher if I didn't include city driving, where I'm lucky if I average 15 in winter. But then it wouldnt be lifetime eh?

A lot of my ABA runs in the same area have reported as high as 39 mpg averages.

Starting to aero the Subie.

My mirror delete showed 39 mpg. Although that was in summer and at a slightly slower speed.