Carbon Fiber/Aluminum build for a family of 5

[StrongFeather]

Let the build begin!!!

After several months of reading, planning and designing, it has finally begun. This is my first trailer build and it's been a lot of fun up to this point. I love projects and I'm really looking forward to this one.

Needs... It HAS to sleep 5 comfortably and be pulled by a Dodge Grand Caravan (backup TV is a Buick Rendezvous). 3/5 of the family loves to camp, and by camp, I mean really camp without "neighbors". The other 2/5 - not so much, hence the reason for this build. Hopefully this build will be the great compromise that will get us into the woods and allow us some incredible road trips.

With that said, in the interest of keeping weight down I've decided on a bolted aluminum frame with a composite (carbon fiber, Kevlar, fiberglass or a combination thereof) shell. It will be 6' x 10' x 5'(interior height), which which will fit the five of us with a little more room than a pack of sardines. Functionally, it will be very utilitarian - just storage and beds. I'll add a V-nose to the front to house the batteries, charger, inverter, terminals, relays and air conditioner. There will be 3'(h) x ~18"(d) of storage storage at the rear.

I'll try to take lots of pictures and explain things as I go. Comments, suggestions and questions are welcome and encouraged.

Steve

[Atomic77]

Let the build begin!!!

After several months of reading, planning and designing, it has finally begun. This is my first trailer build and it's been a lot of fun up to this point. I love projects and I'm really looking forward to this one.

Needs... It HAS to sleep 5 comfortably and be pulled by a Dodge Grand Caravan (backup TV is a Buick Rendezvous). 3/5 of the family loves to camp, and by camp, I mean really camp without "neighbors". The other 2/5 - not so much, hence the reason for this build. Hopefully this build will be the great compromise that will get us into the woods and allow us some incredible road trips.

With that said, in the interest of keeping weight down I've decided on a bolted aluminum frame with a composite (carbon fiber, Kevlar, fiberglass or a combination thereof) shell. It will be 6' x 10' x 5'(interior height), which which will fit the five of us with a little more room than a pack of sardines. Functionally, it will be very utilitarian - just storage and beds. I'll add a V-nose to the front to house the batteries, charger, inverter, terminals, relays and air conditioner. There will be 3'(h) x ~18"(d) of storage storage at the rear.

I'll try to take lots of pictures and explain things as I go. Comments, suggestions and questions are welcome and encouraged.

Steve

Sounds good Steve, make it happen! I am curious to know about your plans for making the composite shell. Good luck with your build journey!

Michael

https://r.tapatalk.com/shareLink?url=ht ... are_type=t

http://www.astroliner.blogspot.com

Sent from my SM-N950U using Tapatalk

[FM82]

Very cool, Steve. Sounds like an interesting build! I am also very curious about your outer skin. Looking forward to seeing the progress.

Sent from my XT1650 using Tapatalk

[StrongFeather]

I am curious to know about your plans for making the composite shell. Good luck with your build journey!

Michael

...and...

Very cool, Steve. Sounds like an interesting build! I am also very curious about your outer skin.

More to come on that, guys, but just to tease you, I'll be making vacuum infused panels with (hopefully) a class "A" finish. The individual panels will be assembled to create the shell. First things first, though, i.e. the frame...

The frame is 6061 T6 aluminum. The main rails are 1x3x0.125. Floor crossmembers are 1x1.5x0.125, 24" on center. The tongue is 2x3x0.25. Brackets are made of 1.5x1.5x0.25 angle aluminum(??? hard to not call it angle iron). Most of the bolts are 5/16, serrated flange head bolts with nylock nuts; axle bolts are 1/2". One of my concerns with the 0.125 wall thickness is a bolt head or nut crushing or pulling through the rail. To prevent that, I'm using aluminum spacers to transfer the crushing force to the outside wall of the rail (look at the pictures below to have a better idea of what I'm talking about). Also, I'm adding a 4' sister beam on each side rail to add width and strength around the (torsion) axle mounting area.

Enjoy some pictures. All of these were taken with the frame upside down, so you're looking at the bottom.

Below is a picture of the main frame rails clamped up to drill holes for the corner bracket and to check for square. If you're wondering, it was within 1/16" of square.


Inside and outside corner shots.



Here are the anti-crush spacers.
This picture shows the holes. The outside hole is 5/16" for the bolt. The inner hole is 5/8" for the spacer.


Here's a shot of a spacer inserted into the hole and one just sitting on the rail.


And another shot of the inserted spacer. In this one you can get an idea of how the crush force from the bolt head is transferred to the spacer instead of allowing it to collapse the outside rail. A 1/4" bracket will take up the load on the inside of the rail.


This is a picture of the passenger side 4' sister rail that will be bolted inside the main side rail. It will add width and strength for the (torsion) axle mount. The four holes and spacers that you can see are for the middle floor crossmembers.


An up-close shot of the floor crossmember bolts and spacers for mounting the sister rails to the main rails. More bolts will be added when the axle is mounted.


When installed, the 1.5" thick plywood/foam sandwich floor will sit on the crossmembers and be flush with the top of the main rails. The sandwhich will be 1/4" plywood top/bottom with 1" XPS foam on the inside, laminated with epoxy and skinned with fiberglass just for fun.

Approximate weight...
130 lbs. of aluminum
20 lbs. of hardware
40 lbs. for floor

I'm hoping for a finished weight of 1,000 to 1,200 pounds, including batteries, air conditioner and mattresses, but before clothes, food, etc...


Steve

[John61CT]

Could you please post a drawing of how the main + sister rails, and nearest crossmembers are oriented v/v the torsion axle mounting?

A napkin sketch snapped with your phone is fine if you haven't done a SketchUp model or something.

Thanks

[FM82]

Sounds like a plan! And yes, that was a tease, indeed. I have a good idea now though. As I was reading along, I was going to suggest rivet nuts, but I'm really liking your use of the spacers.

Sent from my XT1650 using Tapatalk

[aggie79]

Very cool! I'll be following this thread closely.

I've been kicking around the idea of a bolted aluminum frame for some time, but couldn't quite get all of the details in mind. When you get to that stage, please post details on how you connect the a-frame to the main trailer platform.

Take care,
Tom

[KTM_Guy]

How old are the kids? We had a pop up camper when our girls were little, we slep on one side and they were on the other side. And there were curtains they would close. Once they got older 10 or so they liked to sleep in a tent next to the camper. I can’t imagine as the kids get bigger they would want to sleep with mom and dad.

Have you considered a Roof Top Tent for the camper? Mom and dad in the camper kids in the RTT.

Todd

[StrongFeather]

Could you please post a drawing of how the main + sister rails, and nearest crossmembers are oriented v/v the torsion axle mounting?

A napkin sketch snapped with your phone is fine if you haven't done a SketchUp model or something.

You probably wouldn’t get much from a chicken scratch drawing of mine, John.

The axle should be here next week, so I’ll take a picture of the real thing when it arrives.

This may not answer your question, but I’ll try to explain it.

The main side rails run the length of the trailer. The sister rails are only 4’ long and are bolted to the inside of the main rails - effectively doubling the width of the rail to 2”. The axle’s 2” wide mount sits directly below the sistered rail. The axle is bolted to the frame via a vertical plate (or plates) that is as tall as the frame rail and axle mount. The bolts are horizontal and go through the axle mount at the bottom of the plate and through the sistered rail at the top.

The floor crossmembers simply bolt through the sistered rail like the others. Not sure if you can make that out in the pictures or not.


Sent from my iPhone using Tapatalk

[StrongFeather]

Very cool! I'll be following this thread closely.

I've been kicking around the idea of a bolted aluminum frame for some time, but couldn't quite get all of the details in mind. When you get to that stage, please post details on how you connect the a-frame to the main trailer platform.

Take care,
Tom

Thanks, Tom.

It’ll be a straight tongue with two angle support beams rather than a typical A frame. I wanted a longer tongue due to the V nose and rear hatch on the Caravan. The additional support beams might be overkill, but the tongue seems like the obvious weak link.

It’ll all be attached using 1.5” angle aluminum like the rest of the connections. I’ll get you some pictures soon.

Steve


Sent from my iPhone using Tapatalk

[StrongFeather]

How old are the kids? We had a pop up camper when our girls were little, we slep on one side and they were on the other side. And there were curtains they would close. Once they got older 10 or so they liked to sleep in a tent next to the camper. I can’t imagine as the kids get bigger they would want to sleep with mom and dad.

Have you considered a Roof Top Tent for the camper? Mom and dad in the camper kids in the RTT.

Todd

Kids are 10, 12 and 14 (boys rule!!), and I'm hoping that 2 of them will actually want to sleep outside, but we'll see. This project is a proof of concept for us as a family as much as it is for the design/construction. In other words, I don't know if we'll actually use it and I don't know if my out-of-the-box construction ideas will work either. I'm considering it a dual prototype, I guess you could say. The next build may incorporate an RTT, or it might be a teensy-weensy teardrop for one. Either way, I'm loving everything about this and I'm already looking forward to another one at some point.


Steve

[StrongFeather]

The floor crossmembers simply bolt through the sistered rail like the others. Not sure if you can make that out in the pictures or not.

I thought I posted this picture of the crossmembers yesterday...

They are mounted to the side rail with 1.5" angle aluminum brackets, 5/16" bolts and the aforementioned aluminum spacers. The floor will be secured to the crossmembers using 5/16" bolts from below with T-nuts (or furniture nuts) inserted into the floor from above. Oh, and disregard the fact that the angle brackets in the picture are proud of the side rail... we'll chalk that up to a sloppy chop saw. I might shave them down later, but they probably won't be visible once the frame is flipped over. We'll see.

DSC09810.jpg (113.55 KiB) Viewed 7127 times

Steve

[StrongFeather]

Started on the floor today. Nothing too glamorous, but here you go.

The floor will be a 1/8"Plywood || 1"XPS || 1/8"Plywood sandwich, laminated with epoxy and then skinned with fiberglass.

Foam cut and laid out.

DSC09818.JPG (129.86 KiB) Viewed 7127 times

Plywood (bottom) cut and loosely laid on top of the foam. All seams are, or will be, staggered between the three layers.

DSC09819.JPG (132.85 KiB) Viewed 7127 times

Epoxy mixing station. For this part, I'm using "THICK" laminating epoxy from Composite Envisions. Let me tell you, it is thick!


My $.02 on mixing epoxy since I've seen several TNTTT conversations on pumps (volume) vs. measuring cups (volume) vs. weight. Every epoxy should give you a mix ratio of volume and weight. Use the weight method. It's easy, accurate, virtually fool proof, and you don't have to trust the pumps (I know many people use them without issue, but in my opinion they're a potential problem waiting to happen). Anyhow, back to the weight method... get yourself a cheap kitchen scale and a calculator. Decide how much product you want, for example, I was shooting for ~250 grams today. The mix ratio for this epoxy is 100Epoxy:32Hardener. I poured around ~200grams into the mixing cup - it ended up at 208g. Take that number (208) and multiply it by 1.32 (32 being the hardener portion of the ratio), which came out to 274.56g. I slowly added hardener until the scale read 275 grams. It really is that simple. You can work backwards if you know how much mixed product you want. For example, if you're shooting for 800g, the math would be 800 x .32 = 256g of hardener. 800 - 256 = 544g of epoxy. Double check that by taking 544 x 1.32, which should equal 800.


I considered vacuum bagging the layup to clamp the plywood onto the foam, but decided to just use weight instead. I have two very heavy table tops that worked pretty good and they can stay on as long as I need them to be on there. I'll probably pull the weight off tomorrow, throw a concrete heating blanket on top and put the weight back on so it can cure for a couple days. Then flip it over and repeat the process for the top side this weekend.



Steve

[Atomic77]

Just curious, will you be walking on the floor? (As opposed to some tears where the bed takes up the entire floor)

Sent from my SM-N950U using Tapatalk

[lincolnlerner]

My math skills are fading but that mix ratio is bothering me. The second one working back is a bit off to me.