New here. Aerodynamics questions

[Thenorm]

Originally Posted by TomCat60

Yes carbon fiber is very light and strong too. 3 inch walls with 18 R value is sweet for winter camping but those thick walls make it pretty ugly. lol
Tommy

I love carbon fibre. I'm a materials engineer, so it kinda revs me up, so to speak.

[TomCat60]

Your a materials engineer ? Cool :-) What material would you use for this pop trailer project ? Is the cost worth it compared to lets say fiberglass

DBM 1708 Biaxial

Fiberglass Cloth

As usual I starting a project that I know little about and have to learn all the in's and Out's of the available materials and there cost.

If you can share your knowledge with me that would be excellent :-)
Tommy

[Thenorm]

carbon fibre is a very high performance material.
it has a very high stiffness to strength ratio. ideal for situations where weight savings is critical. (race cars, race bycicles, boeing 787). it is not a material for a casual user.

fibreglass has many similar properties, just not as extreme.

honestly its not worth 10x the price just for 10% improvement in performance (stiffness or weight), especially if this is your first big project and there is liable to be some wastage of materials and other excesses.

other materials that are light and stiff include wood (however you will need to pay attention to waterproofing)
also any composite panels (ie. honey comb) are good. these can be pre made or simply like the 2" foam insulation boards with a layer of fiberglass.

aluminum is a metal that is also light and is easy to work with. (drilling,cutting) however it is difficult to weld (requires TIG welding) whereas steel is harder to cut and drill, but any chimp (like myself) can stick/MIG weld it together. A good place to use it is as sheets for the exterier skin.

if you do use any steel make sure it is either stainless (harder than normal steel to cut n weld) or is painted in any exposed locations.

Steel can be a viable material to frame with because it is so strong (mild steel is twice as strong as most structural aluminum, but it is 3 times as heavy) and you won't need to use much.

[freebeard]

Thenorm -- Could you comment on composite panels of the Polymetal/Alumipanel/Grimco MaxMetal type?

I've done experiments hand shearing, rolling, and braking Polymetal. And I'm working on through-fastners.

[TomCat60]

[QUOTE=Thenorm;422771]carbon fibre is a very high performance material.
it has a very high stiffness to strength ratio. ideal for situations where weight savings is critical. (race cars, race bycicles, boeing 787). it is not a material for a casual user. fiberglass has many similar properties, just not as extreme.


Yes I been researching some and fiberglass is a really valid option. Cost wise its a no brainer. $6 a yard versus $40 a yard for carbon fiber.

Now if I used a fiberglass mat like this it seems it would be possible to use one layer of fiberglass on a 2 inch foam board and would be much more cost effective. Have a look at this thick matt and tell me if I am on the right track ok ?

DBM 1708 Biaxial Specialty Fabrics

I have worked with fiberglass a few times rebuilding a corvette fiberglass body so I have a good idea how it all works ! But never carbon fiber !

Tommy

[Thenorm]

Originally Posted by freebeard

Thenorm -- Could you comment on composite panels of the Polymetal/Alumipanel/Grimco MaxMetal type?

I've done experiments hand shearing, rolling, and braking Polymetal. And I'm working on through-fastners.

my knowledge on those products is only limited to the physics behind them. I havent used them. however i can tell you that their stiffness in bending is related to the distance between the 2 skins and the thickness of the skins. the honey comb or foam in between carries very little load and is just a spacer.

Originally Posted by TomCat60

Yes I been researching some and fiberglass is a really valid option. Cost wise its a no brainer. $6 a yard versus $40 a yard for carbon fiber.

Now if I used a fiberglass mat like this it seems it would be possible to use one layer of fiberglass on a 2 inch foam board and would be much more cost effective. Have a look at this thick matt and tell me if I am on the right track ok ?

DBM 1708 Biaxial Specialty Fabrics

I have worked with fiberglass a few times rebuilding a corvette fiberglass body so I have a good idea how it all works ! But never carbon fiber !

Tommy

im havent done much glassing, and not on that scale. my knowledge is more academic. however the bi-axial weave is good. strength in 2 directions. since the foam board can carry a large portion of the load, the glass is going to be for weather proofing and finish and 1 layer might work.
HOWEVER, i am not an expert in glass fabrication i encourage more research.

now, if there are any questions on metals/ metallurgy and refining, those are my real specialties.

[TomCat60]

Quote: Now, if there are any questions on metals/ metallurgy and refining, those are my real specialties.[/QUOTE]

I had to look up that word: Metallurgy is a domain of materials science and of materials engineering that studies the physical and chemical behavior of metallic elements and their mixtures, which are called alloys.

OK thanks for the information and yes I will do more research. My goal is to have zero wood in the Camper and it will be solar powered. I have a Honda 2000i as a backup in case the sun doesn't shine on the panels enough.

At this point it will be fiberglass and minimal aluminum framing. Wood rots and steel rust. It will be pretty simple to put a cone shape on the front top of the camper and round all the corners somewhat. I will design the cab over on the camper to be maybe 2 of clearance above the truck cab. I will be camping mostly locally but if I drive over a hundred miles I can come up with a air mattress deal like others have between the truck cap and the cab over.

I am just looking for something that warm and won't rot. I have had a half dozen RV before and they all get water in them one way or the other. frozen pipe breaks or a 40 mile per hour wind/rain. They all get water in them sooner or later so and fiberglass will fix that.

As far as a RV holding in heat ? One inch walls don't cut it for the Northern Climate I live in so 2 to 3 inch corning ridged board with the fiberglass covering should do the trick.

Here is why I am building the camper for the truck. I can't tow my trailer RV and this little boat I built at the same time so a truck camper will fix that problem.

I almost have all the bugs worked out of my last project now.

https://sites.google.com/site/serenitysolarcanoe/

Tommy

[aerohead]

Here are some structures tested earlier on:







In a zero wind condition you can get full attachment with a radius equal to around 4-5% of the vehicle width as mentioned by members.
In wind conditions the bulbous nose has an advantage.These cod's head noses while best,are most difficult to fabricate.Top and sides need softening.
In times past,tow vehicles would carry a roof mounted inverted boat to aid flow onto a caravan trailer of matching height.
The prow of a boat can have very good air penetration capability as you might imagine.And even with added frontal area could reduce overall drag if carefully configured over a sharp-edged camper shell.

[freebeard]

Thermos bottles aren't 2-3" thick. That's 8-12" out of the width of your pop-up. What would you have for a source of heat?

vacuum bead insulation - Google Search

[TomCat60]

[QUOTE=freebeard;422960]Thermos bottles aren't 2-3" thick. That's 8-12" out of the width of your pop-up. What would you have for a source of heat?

Something very small and adjustable would heat the camper real easy. Like this one that adjust from 1600 btu to 3000 btu would do the trick ! I might only run 5 minutes twice per hour at 30 degrees outside :-)


Camco 57331 Olympian Wave 3 Catalytic Safety Heater camper Trailer RV | eBay

Tommy