"Wind Vane" boattail

[aerohead]

Originally Posted by freebeard

Thanks but my reading of the remit is: "My concern and focus was geared more towards typical RV two axle, large relatively rear overhang applications with "average" drivers in cross wind situations.'

Sound like a singular motor home or pickup camper.

Let's wait for j-c-c to tell us. We've wasted a ton of time already because of non-specificity.

[freebeard]

Agreed.

Last Activity: Yesterday 05:54 PM

[j-c-c]

Sorry to waste anyone's time here, what is lacking here specifically?
This was a bench racing hypothetical question from the get-go.
I will admit the interpretations shared so far have often been a bit off target, and I have tried to steer the discussion back on target, not sure repeating myself is useful nor respectful here.
I don't see the lit lightbulb moment yet.

[freebeard]

Sorry to waste anyone's time here, what is lacking here specifically?

No problem. Some of the best threads result from a one-post-hit-and-run poster.

The context provided in Permalink #9

My concern and focus was geared more towards typical RV two axle, large relatively rear overhang applications with "average" drivers in cross wind situations.

The discussion of rudders and semi trailer tails was from lack of context. A two-axle RV with large overhang could range from a Toyota class C motorhome to a Prevost.

aerohead likes numbers. Wheelbase? Overhang? Width? Height? ....for starters. Aeroforms are a totality. What happens in front can affect the rear --the classic example is a Porsche 911; if you add a spoiler at the back it has to be balanced be an airdam in front.

Pictures help.

Bench racing? Have you seen this:


IIRC 123MPH, or so. Good front pressure gradient, lots of length for reattachment, I forget about the rear difusser, but they had another car on the salt.

[aerohead]

* in #1 (permalink) you speak of a ' big issue with boat-tails in crosswind.'
The only vehicles with 'boat-tails' which exist in the United States are reported to the most desirable to tow.
There are no boat-tails which can be purchased and installed on the existing RV fleet, trailer, or motorhome.
Without 'boat-tails' on the road, I'm struggling with the notion of a 'big issue.'
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* in #9 (permalink ) we find out for the first time that you're concerned with 'typical RV two axle, large relatively rear overhang.'
After 'asking' we still do not know if we're to consider RV travel trailers, or RV Motorhomes/Coaches.
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If you had a particular RV make and model of interest, that we could all look at collectively, we might be able to move the dial.

[j-c-c]

Originally Posted by aerohead

* in #1 (permalink) you speak of a ' big issue with boat-tails in crosswind.' So that "big issue" presumption still stands?
The only vehicles with 'boat-tails' which exist in the United States are reported to the most desirable to tow.
There are no boat-tails which can be purchased and installed on the existing RV fleet, trailer, or motorhome. Personally speaking for myself, I am not limited for solutions that only can be "purchased".
Without 'boat-tails' on the road, I'm struggling with the notion of a 'big issue.'
I suspect this is a case where one must have driven previously a vehicle in strong cross winds that is already sensitive to cross winds and also yearns for a useful solution to reduce drag
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* in #9 (permalink ) we find out for the first time that you're concerned with 'typical RV two axle, large relatively rear overhang.'
After 'asking' we still do not know if we're to consider RV travel trailers, or RV Motorhomes/Coaches. Not sure it matters. Regardless, the concern effects I believe, mostly anything two axle, with large rear overhang, that has any significant sidewalls that cross winds would affect, and that a boattail extension would add additional surface area to help enhance that negative effect.
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If you had a particular RV make and model of interest, that we could all look at collectively, we might be able to move the dial. I don't, it was a hypothetical question, to repeat myself

I guess my assumption of the threads title was fairly description was overly optimistic.

[j-c-c]

Originally Posted by freebeard

No problem. Some of the best threads result from a one-post-hit-and-run poster. Good to know

The context provided in Permalink #9


The discussion of rudders and semi trailer tails was from lack of context. A two-axle RV with large overhang could range from a Toyota class C motorhome to a Prevost. It was meant to.

aerohead likes numbers. Wheelbase? Overhang? Width? Height? ....for starters. Aeroforms are a totality. What happens in front can affect the rear --the classic example is a Porsche 911; if you add a spoiler at the back it has to be balanced be an airdam in front. If balancing of downforce is a primary goal

Pictures help. Of course, but this was a hypothetical discussion.

Bench racing? Have you seen this:


IIRC 123MPH, or so. Good front pressure gradient, lots of length for reattachment, I forget about the rear difusser, but they had another car on the salt.

I have driven those GMC air suspension motorhomes back in the day, stability was not their forte. That LSR recently was impressive, but not something I would attempt.

[aerohead]

It may be solution to a problem which never existed.
It would have to be vehicle-specific.
We'd need to select a case-specific vehicle with which to examine.
Aerodynamics is simple, but not easy.