Boat tail - Redneck style...

[redneck]

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How's it do with the 18-wheeler bow wave and backwash?

Bow waves and backwash do push it around more than before the tail was added. It didn't feel unsafe, it just required paying better attention and a firm grip on the wheel when they were passing.

The big difference is in bow waves between different makes of trucks. Some will push it over a 1ft. or more, while others barely make it wiggle. Which goes to show there is a lot room for aerodynamic improvement by the truck manufactures.

Backwash severity was determined by what trailer they were pulling. Flat beds and tankers seem to have little effect, while boxes obviously had the most (more than average).

The car likes clean air. Mpg is significantly less when I'm their wake according to the computer. So I stay away.

slowmover

Well, since we don't know how the fishing turned out

Caught a few small ones...










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[kach22i]

Originally Posted by redneck

.Bow waves and backwash do push it around more than before the tail was added. It didn't feel unsafe, it just required paying better attention and a firm grip on the wheel when they were passing.

My wife owned two Geo Metro's, it was crazy how much the car felt like it was going to be sucked under a tractor trailer when passing.

It felt unsafe then, don't even want to think about it being a tad worse.

[California98Civic]

Originally Posted by redneck

Bow waves and backwash do push it around more than before the tail was added. It didn't feel unsafe, it just required paying better attention and a firm grip on the wheel when they were passing.

The big difference is in bow waves between different makes of trucks. Some will push it over a 1ft. or more, while others barely make it wiggle. Which goes to show there is a lot room for aerodynamic improvement by the truck manufactures.

You seem to know how to live in the moment... your description of the bow wave is a little like the observation and patience of fishing... great clean project, nice fish too!

[slowmover]

Thnaks for the report on highway speed truck wash. I'll stay a bit farther over, as I do with most RV's.

As to the conerns of others I have the same "problem" (something to solve, not something to fear) with my 8,000-lb pickup fitted iwth an ordinary bed topper. The "problem" is exacerbated when my 35' travel trailer is in tow. Enough that I have bought a larger anti-roll bar for the Steer Axle, and will fit one to the Drive Axle. And maybe a panhard rod. These things do not come without their own price, either. No free lunch. The suspension rise with the wind acting on it is significant.. Without question best tire pressure is a must (not maximum) and the steering gear must be without any slop. IF the changes mean I must slow that much more in the rain, so be it. (Etc).

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[kach22i]

Originally Posted by slowmover

As to the conerns of others I have the same "problem" (something to solve, not something to fear)

A great attitude to have, will get you though some sticky challenges and make this an engaging hobby.

My own modest aero-treatments have a net zero affect on mpg.

Some things I've done have gained me mpg, others added down-force resulted in better handling at speed, so it's a wash.

In the end I feel much safer and with no loss of mpg.

[slowmover]

Originally Posted by kach22i

A great attitude to have, will get you though some sticky challenges and make this an engaging hobby.

My own modest aero-treatments have a net zero affect on mpg.

Some things I've done have gained me mpg, others added down-force resulted in better handling at speed, so it's a wash.

In the end I feel much safer and with no loss of mpg.

Yes, sir, it limits what I am willing to do as FE is only one concern of many . . for example, how would the vehicle of this thread do when loaded to manufacturer weight maximums (fleeing a hurricane in traffic with the family and what we can carry). We do have fun with this game of fuel burn, but larger perspectives put what can be done and what ought to be done in correct perspective.

IOW, when I leave out the full use of the vehicle (passenger and cargo load) I am playing a game . . when I take them also in to consideration I am playiing that same game at a higher level. (A second vehicle moves us farther away from what economy is, IMO).

None of these comments are intended to be critical as to time & effort. A win, as I see it. I may wish to have an Aerolid on the back of my truck, but I may wind up with a stout/secure contractor topper with a full rear door that would need a boat-tail fitted . . security/load volume is a higher priority as to full use of the trucks abilities. Etc. Trade-offs abound.

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[Xist]

Originally Posted by slowmover

Yes, sir, it limits what I am willing to do as FE is only one concern of many . . for example, how would the vehicle of this thread do when loaded to manufacturer weight maximums (fleeing a hurricane in traffic with the family and what we can carry).

Being weighed down would definitely affect many things, but the boat tail should enable the driver to make a faster getaway, although would be a liability when the storm gets too close.

I hope that non of us face hurricanes, with or without boat tails.

[freebeard]

Originally Posted by kach22i

and the steering gear must be without any slop.

No kidding. The most I ever saw was on a farm truck, out in a field baling hay. 1/4 turn of slop. Imagine even 1/10th of that at freeway speeds.

[slowmover]

Originally Posted by freebeard

No kidding. The most I ever saw was on a farm truck, out in a field baling hay. 1/4 turn of slop. Imagine even 1/10th of that at freeway speeds.

That would be an all-too-typical FORD I-Beam front end. Or nearly any live axle / recirc ball 4WD pickup . . . the difference between those and the IFS + rack & pinion on mine (and some others) is night and day.

Both CUMMINS and KENWORTH recommend getting this minimized as corrections per 100-miles is a quantifiable FE problem (trailer movement is problem enough, IOW).

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[slowmover]

Originally Posted by Xist

Being weighed down would definitely affect many things, but the boat tail should enable the driver to make a faster getaway, although would be a liability when the storm gets too close.

I hope that non of us face hurricanes, with or without boat tails.

"High profile vehicles" are sent away from the coast prior to mandatory evacuation. This includes many RVs. But best aero is a help in any situation where the addition of side "sail area" isn't too much of a compromise AFAIK.

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