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Old 04-09-2013, 02:23 PM   #31 (permalink)
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You are an artist with cardboard.

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Just driving down a smooth road, besides gravity, I don't think there are significant forces at play on a properly shaped tail. The bigger issue (I think) is it also has to withstand a lot of sudden bouncing, jolting, jerking around over bumps.
When you're ready to move on to the next iteration, hang weight-lifting weights on the end and take it through a traffic-cone slalom in some parking lot.

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Old 04-09-2013, 02:57 PM   #32 (permalink)
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Originally Posted by skyl4rk View Post
*checks for tail*

I, too, am troubled by my lack of a tail.

I know I am buffeting my way through the atmosphere when I could be slicing through it. I could be saving at least 10% in fuel with a proper trailing edge. I could be passing through the dense fog with far less disturbance to the universe, yet still get where I am going quickly.

I may join thee in this quest for a proper termination of the vehicle body.
Hi,

Actually I think your savings would be way higher than 10%.

The "closing edges" of the Insight are way smaller than the typical car already, so comparatively speaking, the Insight has less of a gain by adding the tail.

A typical vehicle however, has more of a "square back-end" which means the addition of a tail has a much greater energy recovery based on the larger closing area before the tail is added.

If one happened to drive on the freeway a lot, then of course the gas savings are even higher based on the higher air speed.

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Old 04-09-2013, 03:17 PM   #33 (permalink)
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You are a cardboard artist. That looks great! I would be ashamed to replace it with anything else. Just fiberglass over it like has been said many times before. I will likely fiberglass the gaps on my trailing edge, but it is not cardboard.....yet
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Old 04-09-2013, 05:57 PM   #34 (permalink)
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Originally Posted by NeilBlanchard View Post
Sweet, sweet cardboard engineering! it you can just fiberglass over the cardboard (post testing natch!), then you will have a great boattail. Borrow 3-Wheeler's design for the latch cover, and you'll be done.
X2! Someone has to do a "proof of concept" in the real world and you are mostly already there. I love the epoxy resin/foam creations on this site but if there was a cheaper, quick and dirty way to get similar results, We need to see it.

If it tuft tests OK, glass it. I think the regulars on this website all cringed a little when the Firefly boat tail ended up in the recycling bin.
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The power needed to push an object through a fluid increases as the cube of the velocity. Mechanical friction increases as the square, so increasing speed requires progressively more power.
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Old 04-10-2013, 04:31 AM   #35 (permalink)
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I have an idea. If you will cover a cardboard with any even cheapest resin that would give it extra strength and additional resistance for weather conditions.
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Old 04-10-2013, 11:02 AM   #36 (permalink)
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The waterproof wood glue I am using would also work well - no smell and it cleans up with water. It is Titebond III and there is an Elmer's glue that is exterior grade yellow glue that would also work.

I just made another smooth wheel cover yesterday with a scrap piece of cloth and the Titebond III glue. It is dry in under and hour and paints up just fine. The one I made last year is holding up very well.
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Old 04-10-2013, 11:44 AM   #37 (permalink)
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Re: cardboard artistry.... Let's not get carried away, now. It's pretty easy to look good at 640x480!



I'll look into that wood glue idea.

The big issue isn't really the outside surfaces, it's the edges - the corrugation is perfect for wicking up any water that touches it, like a thirsty camel at an oasis.

Also, my plan all along has been to encapsulate the thing in plastic wrap.

This one isn't going to end up in the recycling bin!
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Old 04-10-2013, 02:32 PM   #38 (permalink)
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That is coming along nicely!

Glad to hear it will be saved.
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Old 04-10-2013, 02:52 PM   #39 (permalink)
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Wrap the free edges with 1 1/2" masking tape before weatherproofing.

I dragged out my copy of Paper Houses (Sheppard, Threadgill and Holmes. Schocken Books, New York, 1974). It's pretty good on cardboard constructions. The weatherproofing methods they list (p. 74) are:
Nothing
Boiled linseed oil
Copal varnish
Polyurethane paints
Resin-based paints
Fiberglass
Concrete
Other
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Old 04-10-2013, 04:19 PM   #40 (permalink)
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Quote:
Originally Posted by freebeard View Post
The weatherproofing methods they list (p. 74) are:
Concrete
Use concrete! :P

What manner of plastic wrap will you be using?

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