portable hammock stand CONCEPT?

[peteypk]

Hey there! I am a relatively new hanger, and ever since joining the HF I have been on a part-time quest to find an existing or craft my own portable hammock stand for those instances where I am left with one tree/structure and nothing else -- the one tree hang. I dunno why, but my mind keeps thinking about how to craft one that is as close to portable, durable, and reasonably lightweight, all without being overly expensive. Yeah, yeah, yeah… I know… that is a combination likely to never to see the light of day. But one can dream, right?

There have been lengthy, yet inspiring, threads here on HF like:
@TurtleDog stand
@turtlelady's bamboo stand
@Almosa's portable hammock stand

As well as products like:
Byer of Maine's Madera bipod stand
TreeMount's stainless steel bipod stand

♪♪ But I still haven't found what I'm looking for...♪♪
I think the TreeMount comes closest as it has a great aesthetic… but it's fairly pricey at nearly $200!

I'm no engineer, but I have found myself doodle-sketching possible ideas and taking time at work to noodle through some concepts w/ my engineering-type co-workers. I've even taken to Google SketchUp to mock up some drawings, where most ideas fall short of reality.

However, my latest idea kind of has me jazzed -- I know that this will fall short of the lightweight and inexpensive criteria, but I like its potential as a portable stand. I don't have the budget to buy the materials to test it out, but I figure it might be worthwhile to see where this goes..…. thus, I am posting this for all to critique, and possibly see if someone would dare give it a shot. As I've mentioned, I AM NOT AN ENGINEER, so I ask that you forgive my ignorance of terminology and physics… but I think this might-could work. Yes? No? Maybe?

There are TWO ideas that I wanted to address:
1. COLLAPSIBLE -- the stand is portable because the structure is collapsible, and the bulk of its parts can be packed within itself.
2. COUNTERWEIGHT -- use your own weight, when in the hammock, to counter (partially?) the force that would otherwise pull the hammock stand towards center. I actually have no clue of this would work, but it seems to make a bit of sense in my head? The premise is

So, here are my SketchUps -- they're incomplete without the bolts/wingnuts and the telescoping pins. But I hope these drawings are able to give you the big picture. I'd love to hear your thoughts on how to improve on this, or if this idea is even viable. (Be kind )

[gmcttr]

I'm no engineer but like to think I have a fairly good "feel" for these things.

I'm confident the "counterweight" system just sets up a series of opposing forces in the system that cancel each other out. No gain, no loss.

What appears to be left then, is an Alamosa stand with a telescoping pole.

[trippaw]

I think there is more to it than that. Since that lower arm extends out from the main pole, you get some leverage working for you. Imagine extending it further with theoretical frictionless pulleys. I could be convinced that it would indeed pull outward with similar forces to what your weight is putting on the hammock side.

I am actually curious as to how cranes work. They have the top portion, the jib, that leans far forward. There are some pretty sophisticated mechanisms at play there to keep the cranes from tipping. I'll have to dust off some of my physics!

[gmcttr]

...I am actually curious as to how cranes work...

Massive counter weights.

[peteypk]

Since that lower arm extends out from the main pole, you get some leverage working for you. Imagine extending it further with theoretical frictionless pulleys. I could be convinced that it would indeed pull outward with similar forces to what your weight is putting on the hammock side.

I'm thinkin' the same. As I'm thinking more and more about this, I think I should have extended the "braces" to add for more leverage.

I'd sure love it if an actual engineer could figure out the correct angles and tensions and compression forces and anything else that would make this, or something similar, to work. ;-P

[Tjalling]

I think there is more to it than that. Since that lower arm extends out from the main pole, you get some leverage working for you. Imagine extending it further with theoretical frictionless pulleys. I could be convinced that it would indeed pull outward with similar forces to what your weight is putting on the hammock side.

Sorry guys, according to this assumption I can lift myself of the ground by pulling my crotch upwards. Michael Jackson couldn't do that and no one can.
To hold the hammock all the forces necessary must come from the soil (like a tree does).

I will not bother you with diagrams, but beleive me. Each stake need to hold a force in the order of half your weight.

[peteypk]

Agreed. But I think you misunderstand the idea I'm chasing after. The counterbalance is not intended to support the stand and hammock all by itself. I was thinking that the weight, when in the hammock, could be used to help alleviate the pull force on the stand by pulling on the stand from the opposite side. Does that make more sense?

[Alamosa]

I am having to look at the pictures on my phone, so I may have missed something, but here is my take on it:

I don't think the leveraging arm will have any reduction in the pull on the guy-lines. Overall, the stand has to over-come the compression forces along the top of the hammock and I don't see anything in that leverage arm itself that will reduce that.

The main difference between this and using one end of my stand is the extension legs (and that is huge). They will impact the pull on the guy lines by counter-acting against the leverage of the pole.

I do see the leverage arm having an impact on the strength of the forward extension leg. However, I would be careful of the connection point for that arm as it will have a tremendous amount of stress on the pivot point. It could very easily snap right there. Personally, I think a hard connection for the support, instead of a levered arm would work just as well.

[Tjalling]

A picture paints a thousand words (I hope). In the diagram the arrows represent forces. The length is proportional to the size of the force (is size correct? I am not a native speaker). I could bore you to death with sinus, tan and cosines to calculate the relation between the forces. Bottom line is that each stake needs to hold approximately 40% of your weight in the direction given in the diagram. That is a lot. The force on the base plate will be about 150% of your weight, but that will not be your first concern.




BTW have a look at the anchor of the treemount stand. It is supplied with 6 double stakes!

[half-a-jeep]

By the way, I am an engineer, and I'm trying real hard to NOT sound like a smarty pants, but there are a few flaws in your design. While it would probably work, it's overly complex and has a weak point that could cause it to fail.

This picture pretty much says it all. All you've done is brace the pole so it can transfer more force into the ground, and while that does reduce the forces on the guy lines, the same effect could be accomplished by moving the bottom of the pole towards the hammock.

Another problem with your design is that the brace acts laterally on the center of the main pole, while the lines are pulling on the end. Hollow metal poles are not good at being levers, so the pole could bend at the bolt, depending on the thickness/strength/material. Poles are very strong at resisting axial loads (like a column) so this is why (in general) they only have forces at the ends (ropes at one end, ground at the other, nothing in between).

Sorry for tearing apart your design. You can still use a telescoping pole and Almosa's anchors for a nice portable rig.