Aerodynamic trailer plans

[OP827]

Sketchup is not difficult to learn and previous versions are free. I have learned how to use it in a matter of few hours by coming across this site and watching videos, very good tutorials and a link to download the software.
https://jayscustomcreations.com/sketchup/

I am also building a larger lifting roof foamie with epoxy fiberglass surface, now close to finishing. I did a small overhang in the back of my trailer to help with aerodynamics and structure. When in transport mode the roof is same height as TV. Good luck with your build. Hope the above info helps.
OP

Do you have any videos or photos of your build?!?! Sounds right up my alley!

Yes, click the link in my signature below


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[jimbo69ny]

Sketchup is not difficult to learn and previous versions are free. I have learned how to use it in a matter of few hours by coming across this site and watching videos, very good tutorials and a link to download the software.
https://jayscustomcreations.com/sketchup/

I am also building a larger lifting roof foamie with epoxy fiberglass surface, now close to finishing. I did a small overhang in the back of my trailer to help with aerodynamics and structure. When in transport mode the roof is same height as TV. Good luck with your build. Hope the above info helps.
OP

Do you have any videos or photos of your build?!?! Sounds right up my alley!

Yes, click the link in my signature below


Sent from my Moto G Play using Tapatalk

Well there goes my night, that is a lot of content to review. I also found your photos on your profile. Gotta go guys, lots of reading to do. haha!

 

[timm-TNT]

You may find my wind tunnel (CFD) simulations interesting. I've done a couple different situations with my car (2010 Honda Civic Coupe) towing various shapes of trailers.

Just Car
Drag = 270 N

With 5x8 Enclosed Trailer
Drag = 820 N (3x Car Drag)

With Normal Teardrop Trailer
Drag = 710 N (2.6x Car Drag)

So according to my math, my car would go from about 38 MPG to about 17 MPG pulling a normal teardrop, and it would drop to about 15 MPG pulling the 5x8 enclosed trailer.
I'm not sure exactly what decrease in range you would see pulling the shape you've proposed but I'm guessing it would be a pretty significant decrease. Probably not half like I would see with my car though.

There are a bunch of things you can do to make a design more aerodynamic.
- Reduce the gap between the vehicle and trailer
- And wheel fairings in front of and behind the wheels (Google wheel pants)
- Add a boat tail
- Lower the roof of the trailer
- Round all exterior corners

Here's a sneak peak of the trailer design I'm working on right now, so far it's much more aerodynamic than the normal teardrop shape while maintaining about the same amount of internal room.

The air splitter on the front takes care of the turbulent air between the car and the trailer. I still need to add wheel fairings but other than that this is a pretty aerodynamic trailer.

 

[jimbo69ny]

Wow I love your work! Great job! That is a really sweet program you're using.

Since posting here I have a totally new design in my mind. I dont have an awesome program like yours (or the skills to input the data) so i am using graph paper. Ill work on it tonight and post it asap.

 

[jimbo69ny]

Here is what I am thinking for my build. It would fit directly in the slipstream of my Rav4.

 

[Tigris99]

You may find my wind tunnel (CFD) simulations interesting. I've done a couple different situations with my car (2010 Honda Civic Coupe) towing various shapes of trailers.

Just Car
Drag = 270 N

With 5x8 Enclosed Trailer
Drag = 820 N (3x Car Drag)

With Normal Teardrop Trailer
Drag = 710 N (2.6x Car Drag)

So according to my math, my car would go from about 38 MPG to about 17 MPG pulling a normal teardrop, and it would drop to about 15 MPG pulling the 5x8 enclosed trailer.
I'm not sure exactly what decrease in range you would see pulling the shape you've proposed but I'm guessing it would be a pretty significant decrease. Probably not half like I would see with my car though.

There are a bunch of things you can do to make a design more aerodynamic.
- Reduce the gap between the vehicle and trailer
- And wheel fairings in front of and behind the wheels (Google wheel pants)
- Add a boat tail
- Lower the roof of the trailer
- Round all exterior corners

Here's a sneak peak of the trailer design I'm working on right now, so far it's much more aerodynamic than the normal teardrop shape while maintaining about the same amount of internal room.

The air splitter on the front takes care of the turbulent air between the car and the trailer. I still need to add wheel fairings but other than that this is a pretty aerodynamic trailer.

your calculations are way off for MPG losses.

Aerodynamic drag is a function of speed as well. And for MPG the loss is a variable of the speed. But that's only a portion of determined MPG. The weight of the vehicle, load weight, trailer weight etc all effect that.

My CRV only lost about 15% at 55mph towing something 1500lbs , some front angles and square back. Your not going to loose half your fuel mileage because of a large increase in aerodynamic resistance.

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[timm-TNT]

You are correct that fuel mileage is dependant on multiple things, however, my calculations have taken pretty much everything into account. Of course, I can't say for sure that my math is perfect without building the trailer and doing testing.

I calculated the mileage losses at 62 mph, which means your 15% decrease in mileage would probably be closer to 20%. You also have to consider that a CRV has a larger engine than a Civic so it will tow a trailer easier. Considering aerodynamic drag and rolling resistance are basically the 2 major things contributing to fuel mileage it doesn't seem crazy that tripling the aerodynamic drag and multiplying rolling resistance by 1.5 would reduce mileage by half.

 

[DaddyJeep]

I have read this article a couple times during my designing. There are some interesting facts in here. It appears that the leading edge of your trailer is far more important that the trailing edge.

https://www.nasa.gov/centers/armstrong/ ... -DFRC.html

I will definitely read this article. However before doing so I have to say that the leading edge would be the front of the car. If I can minimize the gap between the rear of the car and the front of the trailer, the front of the teardrop isnt as important.

There was another thread here on this site that showed the different aero turbulence points but here is a link that also shows it.

https://www.teamrunsmart.com/articl...13/aerodynamics-101-streamlining-your-trailer

What I was trying to point out is that you are not going to make significant improvements because the TV is what is "cutting" the air. The nasa testing as well as the information on that trucking site supports that. The one guy did all kinds of stuff... side skirts, wheel covers, under trailer smoothing, relocating his license plate, improved mudflaps and he gained 1mpg. That might be a lot if you are driving hundreds of thousands of miles, but for a weekend camping trip it isn't going to be substantial savings. My design is very complicated for the same reasons you are striving for and I realize there will be little gain from my extra work. I spent a lot of time researching aerodynamics for my camper project as well as my son's van project in an effort to gain a few mpg's. I read a bunch of stuff on ecomodder.com and other places and realized there will be very little benefit from complicating things. I also had a couple classes in aerodynamics when I was in college for automotive design. All this said, I am all for working a little harder to make something unique. Build what makes you happy.

 

[Tigris99]

You are correct that fuel mileage is dependant on multiple things, however, my calculations have taken pretty much everything into account. Of course, I can't say for sure that my math is perfect without building the trailer and doing testing.

I calculated the mileage losses at 62 mph, which means your 15% decrease in mileage would probably be closer to 20%. You also have to consider that a CRV has a larger engine than a Civic so it will tow a trailer easier. Considering aerodynamic drag and rolling resistance are basically the 2 major things contributing to fuel mileage it doesn't seem crazy that tripling the aerodynamic drag and multiplying rolling resistance by 1.5 would reduce mileage by half.

yes it has a slightly larger 4cyl but is 4wd and a much larger profile.

Your images show that you actually tested on not actual teardrop (partially flat front) which is a problem for cars. You percentages seem more in line than the way I read the first post of about 50% loss in fuel mileage.

I know a guy who towed one that was production squaredrop (horrible profile) with a Suburu and his losses werent as bad as one would expect combined with 1500lbs of trailer.

Now my old trailer fully load plus stuff in the back and full family in our odyssey the faster we went the better the mileage. 55-60mph loss wasnt bad, got better mpg at 70mph. 4000lb minivan with 2 adults, 2 kids, cooler and gear plus 1500lb trailer. My wifes van is way over powered along with 8speed tranmission for a minivan. Trailer was built flat back but to stay in the draft of the van as much as possible.

Biggest concern with cars is and flat nose space. Getting all crazy is cool (love the lines I'm seeing of going full aerodynamic around here) but weight and eliminating square surfaces front and rear seems to make a huge difference.

Try simply wedging the nose so leading edges stay in cars draft and see how much of a difference that makes compared to benroy/canned ham styles. Or even true teardrop.

Keep in mind that a with a civic weight is going to play as much of a role as aerodynamic drag because unless you live where it's perfectly flat hills are going to be a big issue, even a small grade is going to make it strain alot if you try to push is max rating. and that rating INCLUDES all weight in the vehicle minus the driver and tank of fuel.

Just thoughts of keeping it simple and cost effective versus trying to make a bullet on wheels. But that of course depends on your time and funds.

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[jimbo69ny]

Hey guys I dont want to be a dick but if you want to debate his figures please do it privately or in a new thread.

I am really hoping for real, factual, advice on my build.

Thanks!

 

[Tony Latham]

Hey guys I dont want to be a dick but if you want to debate his figures please do it privately or in a new thread.

I am really hoping for real, factual, advice on my build.

Thanks!

This will certainly be an interesting build to follow.

Hopefully, you can find some balance between the aerodynamic challenge and making it camp-able.

Tony

 

[Tigris99]

Oh I'm not debating, just trying to throw out some thoughts to take into consideration from my experience. Theres A LOT to take into account so I was sharing some info.

I'm following as well because I want see where this goes, has me very intrigued.

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[rowerwet]

The car and tear in My avatar did many trips this way, the focus has a pretty accurate MPG computer.
The whole combination, with fully loaded camping gear cost us about 6 mpg.
The biggest variable is speed.
55 mph cost the least, 60 was 2 more, 65 4 more than 55, 70 and 75 it settled in at 6 mpg, with each reading taken after a half hour with the cruise set.
At 75 mph I was still being passed by many people.

More than one person has found that a kayak or canoe on the TV has increased their towing mpg.

I'm about to rebuild this tear as a bowfront with an arched roof, like the runaway camper roof.

Weight is almost as big an issue as aerodynamic drag, my new build will be foam.

 

[OP827]

The car and tear in My avatar did many trips this way, the focus has a pretty accurate MPG computer.
The whole combination, with fully loaded camping gear cost us about 6 mpg.
The biggest variable is speed.
55 mph cost the least, 60 was 2 more, 65 4 more than 55, 70 and 75 it settled in at 6 mpg, with each reading taken after a half hour with the cruise set.
At 75 mph I was still being passed by many people.

More than one person has found that a kayak or canoe on the TV has increased their towing mpg.

I'm about to rebuild this tear as a bowfront with an arched roof, like the runaway camper roof.

Weight is almost as big an issue as aerodynamic drag, my new build will be foam.

Rowervet, you are saying that it costs you 6mpg less in your mileage comparing to a car mileage w/o the trailer, correct? Just making sure I understand this correctly. What is your mpg for car with trailer then?

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[jimbo69ny]

I just ordered my fiberglass and resin for my T-Rex aero build.

Check out my youtube channel if you want to see my build. youtube.com/jimbo69ny

 

[Andrew Herrick]

So, a small voice of dissidence here

If somebody is interested in pushing the scientific envelope and building a teardrop for the sake of science, then I say, more power to you! But if somebody is interested in building a usable, affordable, aerodynamic teardrop, then I'd humbly suggest there's no reason to substantially deviate from the norm. As has been pointed out by other posters, when towing a lightweight camper with a classic (or similar) teardrop profile and a suitable tow vehicle, there's minimal potential fuel economy improvements.

If you look at anything designed strictly on aerodynamic efficiency - human-powered bicycles, wind turbine blades, albatrosses, stealth fighters - you'll note that none of those look particularly inviting to live in. So, once a design has rounded body corners, underbody skid plates, recessed wheels and a teardrop-esque shape, you've done 90% of the aerodynamic work. Pushing for that extra 10% will harm the functionality of the interior. For instance, with all respect to Timm's CAD mockup - which looks amazing! - I wouldn't want to spend a rainy afternoon in that thing. Looks like a good candidate for a foam-epoxy build, though.

Anyhow, I love the ideas here. It's just worth pointing out for any new builders reading this thread that these are "research" campers and not necessary to build a high-quality camper. The big pro, as I see it, is you'll be able to drive 80 mph to your destination, and I'll be driving 65

 

[jimbo69ny]

So, a small voice of dissidence here

If somebody is interested in pushing the scientific envelope and building a teardrop for the sake of science, then I say, more power to you! But if somebody is interested in building a usable, affordable, aerodynamic teardrop, then I'd humbly suggest there's no reason to substantially deviate from the norm. As has been pointed out by other posters, when towing a lightweight camper with a classic (or similar) teardrop profile and a suitable tow vehicle, there's minimal potential fuel economy improvements.

If you look at anything designed strictly on aerodynamic efficiency - human-powered bicycles, wind turbine blades, albatrosses, stealth fighters - you'll note that none of those look particularly inviting to live in. So, once a design has rounded body corners, underbody skid plates, recessed wheels and a teardrop-esque shape, you've done 90% of the aerodynamic work. Pushing for that extra 10% will harm the functionality of the interior. For instance, with all respect to Timm's CAD mockup - which looks amazing! - I wouldn't want to spend a rainy afternoon in that thing. Looks like a good candidate for a foam-epoxy build, though.

Anyhow, I love the ideas here. It's just worth pointing out for any new builders reading this thread that these are "research" campers and not necessary to build a high-quality camper. The big pro, as I see it, is you'll be able to drive 80 mph to your destination, and I'll be driving 65

I kindly disagree. I have an EV so air resistance and range is VERY IMPORTANT. Sure you can refill your dino juice anywhere in 5 minutes and be on your way. I have to be as resourceful and efficient as possible. That's why I started this thread and thats why I am building an aero teardrop. Its going to be glorious! haha

 

[Andrew Herrick]

I kindly disagree. I have an EV so air resistance and range is VERY IMPORTANT. Sure you can refill your dino juice anywhere in 5 minutes and be on your way. I have to be as resourceful and efficient as possible. That's why I started this thread and thats why I am building an aero teardrop. Its going to be glorious! haha

Ah, you have an EV?! I apologize - I must have missed that information in the comments. Well, you're on the fringe, then. Have you ever considered a tent?

But seriously ... I'm not sure of the dimensions of your teardrop, but it might be worth looking into an aerodynamic rooftop tent setup. Or, since you're pouring all this time into a teardrop build, make it expandable, like an old Kampmaster. Then you can design the shell as aerodynamically as possible and not sacrifice all the quality of space.

 

[jimbo69ny]

I kindly disagree. I have an EV so air resistance and range is VERY IMPORTANT. Sure you can refill your dino juice anywhere in 5 minutes and be on your way. I have to be as resourceful and efficient as possible. That's why I started this thread and thats why I am building an aero teardrop. Its going to be glorious! haha

Ah, you have an EV?! I apologize - I must have missed that information in the comments. Well, you're on the fringe, then. Have you ever considered a tent?

But seriously ... I'm not sure of the dimensions of your teardrop, but it might be worth looking into an aerodynamic rooftop tent setup. Or, since you're pouring all this time into a teardrop build, make it expandable, like an old Kampmaster. Then you can design the shell as aerodynamically as possible and not sacrifice all the quality of space.

Anytime you put anything on the roof you take a 10-20% aero hit. If it was a tent then I would still have all of that set up to deal with, just like a tent, which I am trying to avoid by having a teardrop.

I havent mentioned this in this post but many others, part of my build is a range extending trailer. I built the first one in the world Feb - March of this year. Now I am building a second one. This time I am using a Tesla 85kwh battery pack (pictured in first post). I should come close to tripling my range. Check out my channel for more info if you are curious.

 

[Andrew Herrick]

Anytime you put anything on the roof you take a 10-20% aero hit. If it was a tent then I would still have all of that set up to deal with, just like a tent, which I am trying to avoid by having a teardrop.

I havent mentioned this in this post but many others, part of my build is a range extending trailer. I built the first one in the world Feb - March of this year. Now I am building a second one. This time I am using a Tesla 85kwh battery pack (pictured in first post). I should come close to tripling my range. Check out my channel for more info if you are curious.

Setting up a tent does certainly take more time. But just curious: Do you think you'll do markedly better with a teardrop trailer compared to the 10-20% aerodynamic efficiency reduction of a roof-mounted tent?

Hmm: Is this you? https://insideevs.com/range-extender-te ... ler-video/
Apparently the big shots are interested in a similar concept: https://evobsession.com/electric-car-ba ... dic-power/

As I said: You're certainly in the "for the sake of science" category I'll be curious to see what you come up with.