UltraLight Body Design

[dwgriff1]

But, if you put 10 pounds in your wheelbarrow or if you put 15 or even 25 could you tell the difference?

It is obvious if you are putting 10 and 200, but down at the light end, would it make that much difference?

This is the thread where I asked that very question: http://tnttt.com/viewto ... highlight=

dave

[schaney]

Ok, I need to expand the wheelbarrow example a bit.

Let's make it 50 lbs that I'm moving around. When I walk it around the backyard course, I hardly notice the weight. When I go up an incline, it takes a minor amount of additional effort. Now I find a 6 year old boy or girl and ask them to do the same thing. They'll most likely make it around the yard, but it took notable effort. On the incline, half way they slip and the wheelbarrow falls on them.

In this example I'm my father-in-laws 1/2 ton pickup with a 5.4 V8 and the 6 year old is my Sidekick with a 1600cc 4cyl.

Andrew's post in the thread about his calculation on rolling resistance did a good job of showing the cost. There is a cost, the smaller the vehicle, the more you feel it. I'd love to see some real numbers (with the assumptions used) that show mileage verses additional weight, that bring the real world varibles into the equation.

[deepmud]

I think the older argument by the "engineers" may have been that it would take a lot more work and weight loss to get just a little better mpg - likely true.

However ....... I expect you'd notice 300 pounds in the way a Cavalier "performs" - I used to drive one - you could for sure notice 4 people in the car vs. 2 - and that's about the weight we are talking here - two adults-worth of weight. 300 pounds or so.

schaney, I'd like to see your results, regardless. Looks like you are on the way to making the real thing - so maybe we'll see some real-world results.

BTW- as long we we're being thread pirates (arr!) - my off-road trailer is about 6x8 so a shell of aluminum (or conduit?) and fabric would be pretty roomy.


here it is, off-road, OVERLOADED, lol - but it follows really well over some crazy terrain.

[schaney]

Deepmud, sounds like your trailer is the prefect size. I'm still debating width, it will be 5' or 6'. The prototype is 6' wide. Shooting for a height of 5'. The lenght will be 6 1/2' - 8'. The prototype is 6 1/2'.

Yes, in a hardsided trailer, weight reduction comes at a cost. So you have to weigh the trade-offs and see if they are worth it to you. With this skin on frame structure I expect the price point to be $450-750. So you're not necessarily spending extra money to shave pounds.

[schaney]

So I'd like to get be to the original purpose of my post.

What do people think about a fixed wall skin on frame style camping trailer?

What do people think about the profile?

Thanks, Scott

[deepmud]

I'm wondering what the flat back end will do for dust/dirt getting sucked in thru the back end/or thru leaks in the sides. It's tempting to say do a more teardrop shape lol. The nearest thing I can think of to compare this would be a 6x6 military truck with a soft top and their soft top isn't airtight so not a valid comparison. Would the top be translucent? Would it an rv-type vent on the roof or would it breathe or ?

Your cage looks welded - but you said it would be a break-down unit?

[schaney]

I don't believe the flat back will be a problem. It could get dirty on the outside but a zippered door with a flap should be stuff out.

Fabric will most likely be a waterproof urethane or PVC coated polyester. For ventilation there will be zippered clear plastic windows with screens and some form of screened roof panels. For heat retention and condensation control in colder weather some form of inner liner.

This cage is a break-down one, it has swedged end components that use lock buttons.

[zippypinhead]

"...This cage is a break-down one, it has swedged end components that use lock buttons..."

Source? Also, for the structure are you using conduit or aluminum tubing?
I'm watching this thread with interest but totally different reasons than the camping folks....
I have this funny little British car. It's an absolute blast to drive for an hour or two... by then you're pretty well beat up from the buckboard-like ride and seating not to mention the wind buffeting. And it's not really freeway friendly... tops out somewhere north of 70mph but it takes a while to get there and a hill will kill any speed you have.
So, I currently flat tow it to events with a towbar setup. I would much rather tow with all four tires up on a trailer but I'm limited by my tow vehicle. (Subaru Forester 2,000 pound max towing limit)
My plan is to purchase an aluminum trailer 6' X 10' that weighs under 500 pounds with brakes. The car weighs in at 1200 pounds full of fuel. That leaves me with around 300 pounds to make a structure to keep the weather/dirt off the car. I'll probably even pull the windshield off (2 bolts per side) to keep the profile low. That might require some creative thinking to load the car but will help with mileage/rear visabilty.
I'll probably be back with more questions as I watch your progress.
Zip

Okay, okay, maybe I might toss in an air mattress and camp at an event once in a while....

[schaney]

Zip, Can you add some pictures of this "funny little car" to your album? Love to see it.

The structure is made (will be made) from aluminum tubing. I am working with someone on this idea, although until it's production ready I'm the key contact.

There is notable production setup involved in a product like this. A one-off for the 6x10 trailer mentioned could run a few thousand dollars.

I'm curious, why not go with a high-quality towing cover? Would be notably less expensive and lighter.

[zippypinhead]

I have yet to see a "high quality towing cover". All of 'em will beat the paint to death. I suppose you could get the car squeaky clean and have it shrink wrapped at a boat yard but that's a bit convoluted.
I'll send you a PM though....

[pete42]

I think it would work very well.
If you decide to use aircraft fabric and dope to cover it then it will be expensive, and gallons of dope and paint all add weight.
I use to fly and repair tube and fabric airplanes.
some ice fishing shantys on Lake erie were tube and fabric the roof could be opened just incase the ice became to thin.

[schaney]

"high-quality" ones are normally custom made.

Yes, a fabric cover is more cost effective than dacron and sealing would be.

[Prem]

IMHO fabric base structures are a cost effective way to shave pound.

Absolutely.

However, many of us want durability. Old Airstreams are still in use after 50 years precisely because their exterior lasts and lasts. Hard to beat aluminum for a lightweight and durable exterior.

I keep thinking about paper mache and epoxy also. Brown Kraft paper over thin, curved, spruce lathe. Lighter than anything if done right. Saving that weight to add strength to the chassis, I'd extend Andrew's Pico Light chassis with 1 1/2" angle iron to put a metal perimeter around the entire floor.

I do like your welded, light pipe framework. Reminds me of the skeleton of a Bolus Road Chief and Papoose, the ultimate designs of all time, all aerodynamic and fuel-efficiency factors considered and compromises made, IMHO. And they are standies!

(I'll stick with a 1,250 lb. aluminum cargo conversion though. AirTabs make up for the rear air flow problem of the box shape darn well, but It spends 99% of its life parked and can only be used when parked.)

[schaney]

There are lots of ways to go light ... not sure paper mache and epoxy. Spruce lathe with epoxied dacron might be better.

[Prem]

epoxied dacron might be better

It sure would be, but that's bucks!

If we're gonna spend money, let's make it Kevlar.