Idea fer an inflatable boat tail made from mylar space blankets...

[BamZipPow]

Low cost mylar space blankets could be used to fabricate an inflatable shell (like those mylar balloons) and heat sealed with an iron to shape fairly cheaply. No rigid structure required and could be inflated/deflated fairly quickly by using one of those big valves similar to the Aerobed. It would be an easy way to create a test bed fer shapes that might improve with a more rigid design by proving what worked or what didn't without a major cost investment.

Been giving this some thought and figured someone might chime in with their opinions...

Whatcha think?

[NeilBlanchard]

Hi,

I think it might tend to vibrate and fastening it in place would be the challenge.

[thatguitarguy]

I have been thinking about this also. Concerns of mine were more of safety and of the legality of mounting a highly reflective contraption on the rear of your vehicle. In many instances, if you are reflecting the road from the bottom and sky from the top as well as trees and passing cars, you could become virtually invisible. Some aero-modders like the extra attention they get, others would like less, but going full stealth in the middle of a busy highway would not be a good idea. And mounting a bunch of lights to be seen would require some kind of sub structure, nullifying the handiness of something small and inflatable.

[bennelson]

On the other hand, if the boat-tail hit something, or if another car hit the boat-tail, what would happen?

Without a rigid frame stretching out the boat-tail, it probably wouldn't even scratch the offending car.

An inflatable boat-tail could be much SAFER that a rigid one. I think a material similar to to mylar but with out the shine would be great to work with.

Still, the challenge will be how to attach it to the vehicle in such a way so that it is well attached, but still stows/removes easily.

I would STILL love to see someone ACTUALLY MAKE an inflatable boat tail. There has been lots of talk of it, but I have never seen anyone actually make one yet!
(I will add it to my list of projects, but it wouldn't be til 2012 that I would get to it!)

[stevet47]

I agree that an inflatable boattail would be safer in an accident, but I am not sure mylar is a good material. I think somethink like tent fabric would be better. When mylar rips/punctures the rip just spreads and would destroy the whole thing. In my mind it doesn't have to be completely air tight.
I see 2 options for inflation:
1) Air ducts from lead from the rear wheel wells to the boattail through a simple check-valve (ping-pong ball in a PVC pipe kind of thing).
2) A "Y" is put into the exhaust, one leads to the boattail through the same type of check-valve, and the other into the atmosphere.

The issue with #1 is that I doubt there will be enough pressure to keep it inflated continuously.
The issue with #2 is that you would have to have either a manual control to determine how much exhaust goes into the boattail vs. how much into the air. Or perhaps air could more directly lead into the boattail via the exhaust, and a smaller dia (1/2-3/4") pipe could be welded to the exhaust and make a 180degree bend. This would provide a straight-shot into the boattail, but still provide an automatic escape route for the exhaust when the pressure in the boattail is creating too much backpressure.



This is the kind of thing that I would LOVE to build, and would, except I dont have a car I could do it with. I have been trying to sell my truck for 6months now to buy a small efficient car, but apparently no one wants it.

[thatguitarguy]

Following vehicles are responsible for not hitting the vehicles they are following, but when you alter your visibility or stretch something out past your bumper, you are increasing your own liability.

Mylar is very light, but here in Colorado we've had problems with these things floating away with helium filled 4 year olds, or something like that...

I've also been thinking about Visqueen with a top panel that's clear so you can see out your rear window, and some type of ram air intake with enough volume to keep the boattail inflated without turning it into a parachute.

Too much to think about, and I haven't even blocked my grill yet...

[stevet47]

Originally Posted by thatguitarguy

Following vehicles are responsible for not hitting the vehicles they are following, but when you alter your visibility or stretch something out past your bumper, you are increasing your own liability.

Mylar is very light, but here in Colorado we've had problems with these things floating away with helium filled 4 year olds, or something like that...

I've also been thinking about Visqueen with a top panel that's clear so you can see out your rear window, and some type of ram air intake with enough volume to keep the boattail inflated without turning it into a parachute.

Too much to think about, and I haven't even blocked my grill yet...

TOOO FUNNY about the kid floating away.
The problem with 'ram air' is that the boattail is then acting like a paracute creating a ton of drag. Taking it from turbulent areas should reduce this, but I still think there would be some drag.

[thatguitarguy]

There's more than enough air passing by the vehicle to keep a boattail inflated with some type of ram duct, and if it goes limp at low speed,you're probably not going fast enough for a boattail to be effective anyway.

You wouldn't want to fill it with exhaust, because when you get to work, or wherever, and you have to deflate it and put it inside your vehicle, it's going to have residual exhaust in it and it will stink up your vehicle, not to mention the danger of bringing exhaust gasses into the cabin.

[MadisonMPG]

Hmm, let me brainstormtype.

Use a hood scoop right before it on the bottom, like the ones one teh WRX rally cars, but upside down. Put a fishing pole type rod to keep it from dragging the ground at low speed.

You may even be able to rig up a little fan to keep it inflated at speeds below 40 or whatever.

[stevet47]

hmm. I wasn't thinking about bringing it inside the cabin. I figured it would just always outside. I suppose the fumes would be a problem if you bring it inside.