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Old 01-19-2023, 06:40 PM   #1 (permalink)
Cd
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Failed segmented boattail experiment using drawer slides

I got as far as the last section of the tail, but I'm calling it quits on this project.

I just don't feel confident enough to drive with this.
I am no engineer, and the risk is too great for causing an accident if something falls off while driving.

I did have some things that went right though, and someone else may be able to benefit from this experiment.
The entire tail is easily removed, and can be stored in a walk in closet in less than 30 minutes.
It leaves no drill holes on the outside of the car.
In city driving, the tail retracts. The full length of entire car with the tail retracted is slightly shorter than a Toyota Camry.
I also had full functionality of the hatch and glass.

This is a video that shows the extension and retraction of the tail from the driver's seat.
It is cable operated.
The last part of the tail is not installed at this point, and the segments are crooked here -
It functions the same with the last section and lights installed.
If you look closely, you can see the lst section of drawer slides.

https://youtube.com/shorts/ZyWfZoQZKGI?feature=share

The car is bare metal with an aircraft theme. Obviously, it has started to rust.
I planned to fix this later.
By using Gibb's lube and a spray sealer, the metal will actually stay pretty rust free.
There is a bare metal car that runs on the SALT flats using this technique, and it seems to work great.







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Old 01-19-2023, 06:51 PM   #2 (permalink)
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This is a mock up of how the finished car was going to look :
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Old 01-19-2023, 08:24 PM   #3 (permalink)
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Not streetable isn't necessarily the end of the story.

Is it in that walk-in closet? Are you comfortable driving with it retracted?

I have a Golf rear wing that has a safety cable threaded through it. Maybe that's all it needs.

I would hope you at least do some testing at a closed circuit. Tuft testing and a telltale bicycle pennant so you can see how much the last section bounces up and down.
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Old 01-19-2023, 09:01 PM   #4 (permalink)
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Yes. It is in my closet at the moment.
I'm not sure about driving it retracted.
Airflow is such a weird thing, and as you are aware, a design must be strong enough for 80 MPH wind in multiple directions, as well as changing forces that pull at the structure.

By the way, I'm curious if you see a video link in the first post.
If so, does it work ?

I attached an image to that first post, but then later tried to delete it, but it still shows up as a thumbnail.
It's a sideways image.
I do everything on my phone, and posting is a bit cumbersome sometimes.
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Old 01-19-2023, 09:22 PM   #5 (permalink)
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The Youtube short works.

How much detaches? The louvered hatch included?
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Old 01-22-2023, 01:53 PM   #6 (permalink)
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Thanks.
Yes - everything detached.
The coroplast hatch and side panels came off with four bolts.
Everthing rides on a "shelf" that was held on by a heavy duty ratchet strap. ( 10,000 lb ) that connected to tow hook on the frame.
The ratchet strap is wrapped around the inner bumper and feeds through and comes out the bumper cover.

The cables you see in the photo holding up the floor are temprary placeholders at that time.
They actually connected to bolts on that "shelf" to help it from drooping.

The drooping problem is a big one.
The whole assembly wants to slide downward on the bumper, no matter how tight I have the ratchet strap.


If I return to this project in the future, I will ask for advice as I go.



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Old 01-22-2023, 03:25 PM   #7 (permalink)
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Quote:
The whole assembly wants to slide downward on the bumper, no matter how tight I have the ratchet strap.
Sounds like a job for a four-bar/pantograph linkage.
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Old 01-22-2023, 04:38 PM   #8 (permalink)
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Cd, this is great!
You are so close that you shouldn't give up!

Maybe still work on the first, stationary part. It gives the largest effect and no moving parts. Once you're good with that add the next part, etc.
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Old 01-22-2023, 05:01 PM   #9 (permalink)
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What happened to the images ?
I must have deleted them by accident when I was editing.
I'll repost them on the first post.

BTW, That third image is from next to a F-150. His bumper is level with the front of mine.
If you notice, his bed is just slightly shorter than the end of my tail.

Last edited by Cd; 01-22-2023 at 05:12 PM..
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Old 01-22-2023, 05:36 PM   #10 (permalink)
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Here is a low angle video without the retraction.
It is cable operated from the driver's seat, but I was originally planning to use an R/C servo used for large planes :

https://youtube.com/shorts/_8jlq2eCInE?feature=share

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