On Sun, 16 Sep 2007 19:55:07 -0700, RickH
wrote:
On Sep 16, 9:23 pm, Sevenhundred Elves
wrote:
wrote:
Bob Ward wrote:
On Sun, 16 Sep 2007 11:23:44 GMT, "Jerry Foster"
wrote:
I don't know the geometry of your chairs, but, in the case of a simple
hammock, the tension on the supports greatly exceeds the weight of
the person in the hammock. How greatly depends on how much the
hammock is allowed to sag.
I question your geometry.
I question your trigonometry.
Especially on a simple hammock, where the design requires TWO points
of support. No way can you DOUBLE the user's weight by any kind of
angle trickery.
What is the tangent of 90 degrees?
Xho
Maybe you should explain what kind of hammock you mean. I think I know
what you're getting at, and what the misunderstanding is.
Below is my idea of a hammock. In this type of hammock the fasteners are
attached to the beam. The only force on the fasteners is what is
necessary to hold up the seat and its occupants. (ASCII art,
non-proportional font required for viewing)
_____.___________________________________._____
|_____|___________________________________|_____| -- Beam
|| 0-- Fastener 0 ||
|| | | ||
|| | | ||
|| | | ||--Support
|| | | ||
|| | | ||
|| | | ||
|| |-- Chain | ||
|| | | ||
|| | | ||
|| | | ||
|| | _________________________________ | ||
|| |/ \| ||
|| | | ||
|| | | ||
|| | Backrest | ||
|| | | ||
|| | | ||
|| | _________________________________ | ||
|| |´ `| ||
|| | Seat | ||
|| |___________________________________| ||
|| ||
|| ||
|| ||
|| ||
\\// -- Grass \\//
That's a "Porch Swing" seat in the USA, and the beam is often the
roof structure of the porch it's mounted on.
But I believe you were thinking about something like what I've shown
below. In this type of hammock the force on the fasteners easily exceeds
the weight of the seat with occupants, because of the geometry, just
like you say.
The drawing below is impractical unless you have some very strong
support posts, or they have back-guys on them, from compound leverage
you will be concentrating a LOT of force pulling the two posts
together. If you had to do it, the chains would need to have a lot of
slack to ease the tension load - and you are still going to need
either very mature trees for posts or back-guys.
| | | |
|___| Fastener |___|
|___}0 0{___|
| | \ / | |
| | \ / | |
| | \Chain / | |
| | \ / | |
| | \ / | |
| | \ Ring Chain Ring / | |
| | 0-----------------------------------0 | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |--Support
| | |-- Two Chains - One each side -- | | |
| | | to backrest, one each side | | |
| | | to seat to minimize fore-aft | | |
| | | instability | | |
| | | | | |
| | | _________________________________ | | |
| | 0/ \0 | |
| | | | | |
| | | Backrest | | |
| | | | | |
| | | | | |
| | | _________________________________ | | |
| | 0´ `0 | |
| | | Seat | | |
| | |___________________________________| | |
| | | |
| | | |
| | | |
| | | |
\\||// \\|||//
This should neatly reconcile your different opinions, I hope.
S.- Hide quoted text -
- Show quoted text -
Oh my god, you've got way too much free time on your hands
Me too. And your point is...? ;-)
-- Bruce --