Inflatable boattail

[aerohead]

Here's an image progression for an inflated boat tail on a 1st-gen CRX.
The 3 articulated nested-pans serve to add some rigidity at the base,and dampen aeroelastic effects that would otherwise wag the tail.
Piggy-backing onto a cruise control circuit would allow for automatic operation.
Some micro-switches and a locking solenoid would be involved.A 2-way reversing damper would allow for inflation and evacuation of the envelope,with a 12-VDC blower doing the heavy work.Once the envelope is pressurized,the fan is acting against a dead head,and current demands fall off.
When pan#2 is perpendicular to the road,it' drag helps with the deployment.

[MetroMPG]

Fun!

Unless I missed it, we've yet to see someone with some "inflatable" fabrication skills on the forum. But whenever I see the Macy's parade or a bouncy castle, I always find myself thinking: boat tail.

[Cd]

Now would be the time to snatch up some X-mas inflatable yard crap ...er.. decorations.

At my job they have those things, and some of them have a two prong plug.

Now is the time to look for one that is damaged, or just the blower unit itself.

However, I imagine you could just use wind to deploy a boat-tail if you simply had a cone with a hole at the back end and some means of retraction.

[aerohead]

Originally Posted by Cd

Now would be the time to snatch up some X-mas inflatable yard crap ...er.. decorations.

At my job they have those things, and some of them have a two prong plug.

Now is the time to look for one that is damaged, or just the blower unit itself.

However, I imagine you could just use wind to deploy a boat-tail if you simply had a cone with a hole at the back end and some means of retraction.

Bruce Ruefer,in Lubbock,Texas had a rig he was inventing/testing which used Bauman scoops to fuel the envelope with pressurized air in the mid-1990s.
I've tried to locate him online to no avail.
Texas Tech Aero Lab was helping him on the project.
The trail has gone cold.

[aerohead]

I stumbled across this online.It contains Bruce Ruefer's patent concept.
https://repositories.tdl.org/ttu-ir/...pdf?sequence=1

[aerohead]

This was my first foray into an inflatable boat tail.
*A wooden box hung from L-brackets slung over the tailgate.
*The 'long' part of a bean-bag chair created the envelope,simply stapled to the box.
*A 12-VDC ventilation fan from a Westfalia Campmobile was the prime mover for inflation air and tension.
*A simple,clip-on umbilical power chord exported current from the host vehicle's battery.

[freebeard]

I don't recall seeing the thread before; so, for sake of completeness, here's my proposal for a vehicle that is taller than it is wide:



Maybe not so much inflated as rigidified with hinged or telescoping fiberglass rods, or high-pressure hoses. The bottom edge would swing down and forward until is seals against the rear valance. The vertical piece at the tip is to accommodate the height/width proportions.

[nimblemotors]

like that freebeard, y'know if you can make something robust and simple the truckers might go for it, and could make a few bucks.

Inflatables don't have a good track record for not leaking eventually,
and would need high pressure to maintain their shape.

[sheepdog 44]

Is the bottom image with boat tail fully deployed roadworthy? I've been under the assumption the 80% of template drawings applied to modern cars would all make contact with the road at some point because their wheel bases are too short and too far forward compared to the "ideal" car. My mind has always mentally added a hinge halfway on a tail that allows that part to move up so you don't rip the whole thing off the car.

Originally Posted by aerohead

[aerohead]

Originally Posted by sheepdog 44

Is the bottom image with boat tail fully deployed roadworthy? I've been under the assumption the 80% of template drawings applied to modern cars would all make contact with the road at some point because their wheel bases are too short and too far forward compared to the "ideal" car. My mind has always mentally added a hinge halfway on a tail that allows that part to move up so you don't rip the whole thing off the car.

The tail is only deployed on the highway,where ground clearance isn't an issue.A cruise-control logic could operate it automatically.The driver would do nothing.
The rigid lower structure eliminates any tendency towards a Karman vortex street-type vertical oscillation.
I simulated the underside support for the envelope on the T-100.It was fine at highway velocity.

It's my experience that it's roadworthy.