Construction question

Anything to do with mechanical, construction etc

Re: Construction question

Postby Tigris99 » Sat Oct 20, 2018 8:26 pm

it covers everything except skinning the foam.

Sandwhich wall design is the SAME whether foam or wood. Still have to plan everything out accordingly, have supports built in correct places inside the walls for any fixtures, holding shelving and so on.

However you will never find a book on building foamies, have to have the ability to think and apply the details from sandwich builds as well as information from other foamy builds here.


And you can simply skin foam in fiberglass anyway. You need a specific epoxy which is quite expensive to do so. Otherwise the foam will melt, become toxic and so on.

You cant go into building your own unless you have base skills, tools and take the time to learn how to build these. Especially foamie as they are more than a wooden box on wheels which anyone with some plywood, 2x4s, box of screws and a cordless drill can build.

Sent from my SM-G950U using Tapatalk
Tigris99
Teardrop Master
 
Posts: 252
Joined: Fri Mar 03, 2017 4:42 pm

Re: Construction question

Postby noseoil » Fri Oct 26, 2018 9:57 pm

Look into aerodynamics & shapes. Basically, the trailing end is more important than the leading end, since the tow vehicle breaks the entry into the wind. Taper the back & you're good. If you tow with a small car, the front is important, but not as much as the rear (as the air exits the shape)...
Build log: viewtopic.php?f=50&t=60248
The time you spend planning is more important than the time you spend building.........

137905
User avatar
noseoil
1000 Club
1000 Club
 
Posts: 1820
Images: 669
Joined: Sun Apr 27, 2014 8:46 am
Location: Raton, New Mexico, living the good life!

Re: Construction question

Postby Xanthoman » Fri Nov 02, 2018 10:29 pm

If someone, say me, were to write a book on foamies or other manual on teardrops, what would you say is the most important parts not currently covered in the prior work mentioned?

I just graduated with my mechanical engineering degree with emphasis on composites and sandwich structures so can explain quite a lot of how they function and to do the design of them.

I just bought all of my materials for my build and, after I am done remodeling my kitchen this week or next, I will start on it. I am designing for production of at least two, but if my concepts work several teardrops by doing my build like a boat hull built from the outside in. So my first will be a wood/foam hybrid but the second and latter would be pure foam with fiberglass shell. My foamie isn’t mentioned at all in any of the foamie pages even, so it’s purely new and untested.

I have read significantly into the classical foamie methods but I am going a more expensive route primarily to pioneer my prototype concept. I could synthesize and write a manual on it still, and provide the engineering theory to help give design assistance for creativity.

I have also noticed no one has done, to my knowledge any great parts, pieces, and layout of propane systems either...

I’m thinking if I were to write a manual, it would include:
1. Chassis/Trailer Base Design
2. Classic Wood Methods
3. Classic Foamie Methods
4. Advanced Foam/Hybrid Methods
5. Electronics and electric systems
6. Propane and gas systems
7. Fenestrations
8. Details of weight, drag/aerodynamics, and watertightness
9. Galley concepts and innovations

That’s just a quick list I came up with, but curious to know thoughts from people what is most ambiguous and needs addressed in a compiled work. Obviously I need to build some stuff and such before I can finish/start a manual, but I think I have the right skill set to do a good job on it.
Xanthoman
Teardrop Advisor
 
Posts: 58
Images: 3
Joined: Sat Sep 24, 2016 2:02 pm
Location: Rexburg, Idaho
Top

Re: Construction question

Postby Xanthoman » Fri Nov 02, 2018 11:32 pm

As to the OP, your system would be quite light. If you buy 1/8” plywood and glue it to the foam (1-1/2” for example) sheets and then build a box out of them, it would be very stout. If you layered that in a bonded fabric to tie at all together it would be even more stout!

If you are going for as light as possible I would think a wall thickness of 1-1/2” foam panels, with top hat stiffeners every 16” on the interior, (just a foam batten really), covered with a lightweight bedsheet and epoxied to both sides of the foam would do the trick. Epoxy generally won’t dissolve XPS like polyester resins. You could then sand the exterior and spray a good quality exterior paint such as Duracraft by Sherwin Williams, or leave the bedsheet pattern and polyurethane it with a UV resistance Poly. Or roll monstaliner over the whole thing and call ‘er good. Or spray a gelcoat if you want it to look super slick...also, a a sandwiched floor of 2” thick with 1/8”skins, (or .040” Aluminum or so for the bottom skin) should suffice for rigidity and save a ton of weight; I see so many people overbuild the decks that they gain a lot of unnecessary weight there. I could run the actual math to determine an actual number of loading and how robust the sandwich should be if you would like.

As far as aerodynamics; https://www.simscale.com/blog/2017/06/a ... ilf1l-svg/
This image shows some basic shapes and their drag coefficients. Higher drag coefficient, more drag. Ideally you taper at the back to reduce pressure area but in so doing you can increase friction drag by more surface area. A rough surface like PMF or just a rolling texture from a paint roller would suffice in giving it just enough to maintain boundary layers longer actually beniftting the drag over a super glossy smooth surface, but shape and speeds would come more into play to nail down the best texture for drag performance.
Xanthoman
Teardrop Advisor
 
Posts: 58
Images: 3
Joined: Sat Sep 24, 2016 2:02 pm
Location: Rexburg, Idaho
Top

Re: Construction question

Postby Tom&Shelly » Sat Nov 03, 2018 8:53 am

Xanthoman wrote:If someone, say me, were to write a book on foamies or other manual on teardrops, what would you say is the most important parts not currently covered in the prior work mentioned?

I just graduated with my mechanical engineering degree with emphasis on composites and sandwich structures so can explain quite a lot of how they function and to do the design of them.

I just bought all of my materials for my build and, after I am done remodeling my kitchen this week or next, I will start on it. I am designing for production of at least two, but if my concepts work several teardrops by doing my build like a boat hull built from the outside in. So my first will be a wood/foam hybrid but the second and latter would be pure foam with fiberglass shell. My foamie isn’t mentioned at all in any of the foamie pages even, so it’s purely new and untested.

I have read significantly into the classical foamie methods but I am going a more expensive route primarily to pioneer my prototype concept. I could synthesize and write a manual on it still, and provide the engineering theory to help give design assistance for creativity.

I have also noticed no one has done, to my knowledge any great parts, pieces, and layout of propane systems either...

I’m thinking if I were to write a manual, it would include:
1. Chassis/Trailer Base Design
2. Classic Wood Methods
3. Classic Foamie Methods
4. Advanced Foam/Hybrid Methods
5. Electronics and electric systems
6. Propane and gas systems
7. Fenestrations
8. Details of weight, drag/aerodynamics, and watertightness
9. Galley concepts and innovations

That’s just a quick list I came up with, but curious to know thoughts from people what is most ambiguous and needs addressed in a compiled work. Obviously I need to build some stuff and such before I can finish/start a manual, but I think I have the right skill set to do a good job on it.


I'll have to think about what I'd like to see addressed specifically; I don't know what I don't know. But if you write a manual like this, I'll buy it!

The part about the engineering theory and engineering aspects of the sandwich structures sounds particularly interesting. (I am an electrical engineer by education, and am always interested in other fields of engineering.) May never build a foamie (in the middle of our first build, which seems like enough at the moment), but would like to know more about how to build teardrops better.

Best of luck with your build!

Tom
172912 170466
Tom&Shelly
Palladium Donating Member
 
Posts: 2180
Images: 1903
Joined: Tue Sep 05, 2017 3:27 pm
Location: Upstate New York/New Mexico
Top

Re: Construction question

Postby jimbo69ny » Mon Nov 19, 2018 10:43 pm

Anyone have some real measurements of weight? I saw someone say that 1" 4x8 foam board weighs 10lbs. What does plywood weigh? what about 1/8" board? how does that compare to fiberglass?
jimbo69ny
Teardrop Master
 
Posts: 129
Images: 10
Joined: Thu Aug 09, 2018 2:53 am
Top

Re: Construction question

Postby Xanthoman » Wed Nov 28, 2018 1:18 am

You will have to extrapolate their sq ftto get your final, but here is some close approximations per one square foot of each; 3/4 ply: 2.188 lbs, 1/2 ply:1.458, 1/8 ply:0.365. (Based on 3/4” ply weighing approximately 70lbs) XPS/EPS/ or CCSPF at 2 lbs density (pretty standard); 2”:0.33,1”:0.167,1/2”:0.083. Fiberglass is a bit harder to reference because you buy it in weight per sq yd/m (depending on supplier) so will be 2oz-24oz (typical size range) divided by 9 to get per layer sq ft weight. Then you have to account for resin which is determined by thickness, not cloth weight. So, I can give you the square foot weight per 1” of thickness and you would have to do a layup of the proposed thickness and measure it with calipers to get how thick it is. (You could measure the fabric thickness and multiply that by layers and get real close). Fiberglass with resin (at about 94lbs/cu ft): 7.833lbs/sq ft@1” thick. So for 30 mil, (.030”):0.235, 10 mil:0.078. These are just calculated by finding a chart of their density and multiplying that by their volume (make sure to use the proper units!). Hope that helps!
Xanthoman
Teardrop Advisor
 
Posts: 58
Images: 3
Joined: Sat Sep 24, 2016 2:02 pm
Location: Rexburg, Idaho
Top

Re: Construction question

Postby jimbo69ny » Wed Nov 28, 2018 6:47 am

Xanthoman wrote:You will have to extrapolate their sq ftto get your final, but here is some close approximations per one square foot of each; 3/4 ply: 2.188 lbs, 1/2 ply:1.458, 1/8 ply:0.365. (Based on 3/4” ply weighing approximately 70lbs) XPS/EPS/ or CCSPF at 2 lbs density (pretty standard); 2”:0.33,1”:0.167,1/2”:0.083. Fiberglass is a bit harder to reference because you buy it in weight per sq yd/m (depending on supplier) so will be 2oz-24oz (typical size range) divided by 9 to get per layer sq ft weight. Then you have to account for resin which is determined by thickness, not cloth weight. So, I can give you the square foot weight per 1” of thickness and you would have to do a layup of the proposed thickness and measure it with calipers to get how thick it is. (You could measure the fabric thickness and multiply that by layers and get real close). Fiberglass with resin (at about 94lbs/cu ft): 7.833lbs/sq ft@1” thick. So for 30 mil, (.030”):0.235, 10 mil:0.078. These are just calculated by finding a chart of their density and multiplying that by their volume (make sure to use the proper units!). Hope that helps!


Thank you. I think more people should know this. This information should be sticky here. Shows that foam has a serious advantage of less weight! People can tell you that but until you see the numbers I think that’s really where it really hits home, at least for me.
jimbo69ny
Teardrop Master
 
Posts: 129
Images: 10
Joined: Thu Aug 09, 2018 2:53 am
Top

Re: Construction question

Postby Andrew Herrick » Thu Nov 29, 2018 2:38 pm

Xanthoman wrote:If someone, say me, were to write a book on foamies or other manual on teardrops, what would you say is the most important parts not currently covered in the prior work mentioned?

I just graduated with my mechanical engineering degree with emphasis on composites and sandwich structures so can explain quite a lot of how they function and to do the design of them.

I just bought all of my materials for my build and, after I am done remodeling my kitchen this week or next, I will start on it. I am designing for production of at least two, but if my concepts work several teardrops by doing my build like a boat hull built from the outside in. So my first will be a wood/foam hybrid but the second and latter would be pure foam with fiberglass shell. My foamie isn’t mentioned at all in any of the foamie pages even, so it’s purely new and untested.

I have read significantly into the classical foamie methods but I am going a more expensive route primarily to pioneer my prototype concept. I could synthesize and write a manual on it still, and provide the engineering theory to help give design assistance for creativity.

I have also noticed no one has done, to my knowledge any great parts, pieces, and layout of propane systems either...

I’m thinking if I were to write a manual, it would include:
1. Chassis/Trailer Base Design
2. Classic Wood Methods
3. Classic Foamie Methods
4. Advanced Foam/Hybrid Methods
5. Electronics and electric systems
6. Propane and gas systems
7. Fenestrations
8. Details of weight, drag/aerodynamics, and watertightness
9. Galley concepts and innovations

That’s just a quick list I came up with, but curious to know thoughts from people what is most ambiguous and needs addressed in a compiled work. Obviously I need to build some stuff and such before I can finish/start a manual, but I think I have the right skill set to do a good job on it.


If you ever do cut the red tape on this project, PM me :) I have a degree in Mechanical Engineering as well, about two dozen campers under my belt, an interest in stressed-skin design, and (although you'd never know it from my TNTTT commentary) I worked as a professional copywriter and newspaper editor for a number of years. I guess that makes me your clone? Not to invite myself to someone else's party, but I'd be happy to collaborate. :beer:
A few of my builds:

ImageImageImageImage


SEE MORE AT: boondockcampers.com
User avatar
Andrew Herrick
The 300 Club
 
Posts: 390
Images: 15
Joined: Mon Apr 25, 2016 5:39 pm
Location: Cedar City, Utah
Top

Re: Construction question

Postby Xanthoman » Thu Nov 29, 2018 6:11 pm

Andrew Herrick wrote:
If you ever do cut the red tape on this project, PM me :) I have a degree in Mechanical Engineering as well, about two dozen campers under my belt, an interest in stressed-skin design, and (although you'd never know it from my TNTTT commentary) I worked as a professional copywriter and newspaper editor for a number of years. I guess that makes me your clone? Not to invite myself to someone else's party, but I'd be happy to collaborate. :beer:


I would be glad to have an accomplice. Especially with someone who has way more build experience in several designs and options. Thanks!
Xanthoman
Teardrop Advisor
 
Posts: 58
Images: 3
Joined: Sat Sep 24, 2016 2:02 pm
Location: Rexburg, Idaho
Top

Re: Construction question

Postby jimbo69ny » Thu Nov 29, 2018 6:39 pm

I could use a hand anyone live near Ithaca NY? Haha
jimbo69ny
Teardrop Master
 
Posts: 129
Images: 10
Joined: Thu Aug 09, 2018 2:53 am
Top

Previous

Return to Teardrop Construction Tips & Techniques

Who is online

Users browsing this forum: No registered users and 16 guests