Roof top wind deflector.

[cracker39]

I did some checking, and at the risk of sounding pedantic , here’s what I found.

Wikipedia defines an RV as “Recreational vehicle or RV is, in North America, the usual term for a motor vehicle equipped with living space and amenities found in a home.â€

[Larwyn]

http://www.rvia.org/Content/NavigationMenu/RVFactsNews/RVTypesPrices/default.htm

[Gage]

Boy, did I turn this thread around. But don't call my Tiny Travel Trailer an RV. It was built back in the 50's before the 'RV' phrase even came about.

[2bits]

I am enjoying the suggestions that address the question since I am starting a TTT myself. We all have our own opinions, but can we please cut Peter a break and not run him off from the group? Lets just try to make our opinions constructive rather than dismissive. Remember this is the "Teardrops AND Tiny Travel Trailers" forum.

[Zollinger]

I am enjoying the suggestions that address the question since I am starting a TTT myself. We all have our own opinions, but can we please cut Peter a break and not run him off from the group? Lets just try to make our opinions constructive rather than dismissive. Remember this is the "Teardrops AND Tiny Travel Trailers" forum.

2bits you are right! We are all here because we love camping, working with our hands restoring or building our trailers. Who really cares about the size. As long as we treat each other with respect, and remember there is more than one way to skin a cat. (Sorry Planovet)

[Miriam C.]

A better answer! A warning again this thread is about the original posters question.

Peter if you would like I can remove all posts that don't apply to your question...

[bohemian]

b.bodemer
I see that you have one of the car top carriers that I was talking about on your truck.
Do you find it helps with the wind deflection?
Wayne

[Pete S]

Here is some Volkswagen* wind tunnel data from a few decades ago:



So that's a reduction of 15% total drag by using the spoiler - huge. But this applies to this combination of European tow vehicle and relatively large, square trailer, so don't no-one go thinking all roof spoilers will give this benefit.

*Did you identify that car as a 1980s Passat by its profile?

The deflector they depict looks like the size/shape you would get if you mounted one rail of yamika/twule rack with deflector. Has anyone tried it?

[Pete S]

I guess I should have asked if anyone had tried this on a sedan. Dale's exploits with a wing on a pickup sound mighty promising. I'm guessing (hoping) the results will be even better on a sedan.

I finished my first attempt at a deflector yesterday and testing will start soon. We figure mpg at every gas stop and we have a pretty good idea how well we do on trips with the TD. It will be interesting to see how this works out...

[PhotoGuy]

An RV magazine did a bunch of studying on this topic. And the figured out the cost to buy the " wing" compared to the amount of money it would save you in fuel..... You would have to tow a lot for a number of years to pay for itself.

[Pete S]

Take a look at these.. we used them on some aircraft with very good results. They work the same with ground vehicles as well...

http://www.sigmaautomotive.com/performa ... ortekz.php

I'll admit that I really haven't spent a lot of time learning about vortice generators. I've been curious but haven't taken it any further than that...

From my days flying my ski-plane all over hellandgone and flying out of most every grass strip I could find I remember guys putting those things on their wing leading edges. I think the idea was that by creating vortices they could make the airflow follow the top of the wing better (longer) at higher angles of attack. That would lower the stall speed by lowering the speed that stall burble happens. Steeper approach-to-landing and steeper initial climb promised they could fly out of shorter fields. How am I doing so far?

Ok, I am trying to see where these could be applied to our teardrops. The way I understand it at highway speeds air can't follow the shape of our teardrops. Instead it breaks away in what is essentially a stall burble. The slope of the top varies between the different types but at highway speeds where do you suppose the airflow separation is what can be done to make the airflow follow more roofline?

One of those "gotcha" things that I think might happen if you added these to the roofline on a sedan/tow vehicle is you would increase the speed and amount of airflow that you direct right into the front of the camper body. I'm thinking that would be counter-productive...

On the other hand if you mounted them on a deflector wing would they reduce the wake-burble? That could be REALLY useful! Right now what I think I have is a lot of air being launched nearly straight up at the front of the camper body. There is a strong enough vacuum over the top that the roof vent will open ALL THE WAY if the handle isn't tied off inside. If I could just get the flow over the camper to be reasonably flat...

So, assuming that I can get "reasonable" airflow over the top of the camper I'm curious what can be done over the back slope. I'm thinking that at highway speeds the airflow doesn't descend very far down the rear slope on a Ben-Roy type like ours. Are you thinking that by making it go another 6 inches or maybe an additional foot down the slope it would reduce the burble area and smooth some of the air in the stall-break area? Enough to make a difference?

I'm thinking a guy could get a piece of angle PVC (or maybe get box-section and cut it diagonally) and make their own VGs. The ones they are making for cars are pretty and all that but the ones I've seen on airplanes are simple flat blades. A little contact cement and let the testing begin!

Ok, who has a wind tunnel???

[Pete S]

An RV magazine did a bunch of studying on this topic. And the figured out the cost to buy the " wing" compared to the amount of money it would save you in fuel..... You would have to tow a lot for a number of years to pay for itself.

When I "look around" on this forum I see a talented bunch of guys and gals who can make just about anything. WAY more talented than I'll ever be. Many can make just about anything out of "pert-near" nothing. How much can a wing cost???

I just finished my first wing attempt. I tried to make it mimic the one in the VW drawing as closely as possible. I already had the roof rack to start with but you can nab those pretty cheap from craigslist. I added a piece of 1/4" plywood that a friend gave me for the project. Basically I'm in this thing for nothing...

I'm guessing we'll save $50 to $75 in fuel in our FIRST OUTING this year. I'm far more concerned about a transmission meltdown (and I have no idea what that might cost). Payback should start in the first 1/4 mile...

Besides, inventing is FUN!!! C'mon, all the kids are doing it...

[Pottercounty]

Take a look at these.. we used them on some aircraft with very good results. They work the same with ground vehicles as well...

http://www.sigmaautomotive.com/performa ... ortekz.php

I'll admit that I really haven't spent a lot of time learning about vortice generators. I've been curious but haven't taken it any further than that...

From my days flying my ski-plane all over hellandgone and flying out of most every grass strip I could find I remember guys putting those things on their wing leading edges. I think the idea was that by creating vortices they could make the airflow follow the top of the wing better (longer) at higher angles of attack. That would lower the stall speed by lowering the speed that stall burble happens. Steeper approach-to-landing and steeper initial climb promised they could fly out of shorter fields. How am I doing so far?

Ok, I am trying to see where these could be applied to our teardrops. The way I understand it at highway speeds air can't follow the shape of our teardrops. Instead it breaks away in what is essentially a stall burble. The slope of the top varies between the different types but at highway speeds where do you suppose the airflow separation is what can be done to make the airflow follow more roofline?

One of those "gotcha" things that I think might happen if you added these to the roofline on a sedan/tow vehicle is you would increase the speed and amount of airflow that you direct right into the front of the camper body. I'm thinking that would be counter-productive...

On the other hand if you mounted them on a deflector wing would they reduce the wake-burble? That could be REALLY useful! Right now what I think I have is a lot of air being launched nearly straight up at the front of the camper body. There is a strong enough vacuum over the top that the roof vent will open ALL THE WAY if the handle isn't tied off inside. If I could just get the flow over the camper to be reasonably flat...

So, assuming that I can get "reasonable" airflow over the top of the camper I'm curious what can be done over the back slope. I'm thinking that at highway speeds the airflow doesn't descend very far down the rear slope on a Ben-Roy type like ours. Are you thinking that by making it go another 6 inches or maybe an additional foot down the slope it would reduce the burble area and smooth some of the air in the stall-break area? Enough to make a difference?

I'm thinking a guy could get a piece of angle PVC (or maybe get box-section and cut it diagonally) and make their own VGs. The ones they are making for cars are pretty and all that but the ones I've seen on airplanes are simple flat blades. A little contact cement and let the testing begin!

Ok, who has a wind tunnel???

Basically, you can use them for the rear of the trailer as well. It helps to break up and soften thus providing for a smooth departure over the end of the trailer lessening drag..

[Pete S]

Cool! I might try it on the top, just ahead of the galley hinge. I'm not sure I want to catch my clothes on them all the time if I put them along the sides.

I wonder if they would work underneath too? Maybe section a 6" plastic pipe and mount it at bottom leading edge of the camper body, round side forward, to move the flow down a couple inches and add VGs to smooth the flow. Leading and trailing fairings on the axle itself... (styrofoam covered with aircraft fabric might be flexible to stay on a while) Hmmm...

But back to the wing, what would you think would work better there. A bunch of small, leading edge style, VGs or the larger style VGs (like late model jets) on the tips of the wing?

[john warren]

i know from experiance , when i had a cap on my ford ranger i didn't lose a significant amount of milage when towing the teardrop. without it i lost about 5 mpg. guess i'll build a new "teardrop" cap this summer