falling challenge big tulip through deck

Well, here goes. This https://arxiv.org/pdf/physics/0210033.pdf has the equation for a falling chimney (e.g. the ones that crack apart on the way down) and the angular acceleration is proportional to sine of the angle from vertical. Oddly, the acceleration is inversely proportional to the length of the log but independent of its weight or density. They then say that the angular velocity is proportional to (1-cos (angle from vertical)) with the same odd independence as the acceleration. Once you have angular velocity (vs angle of top/log from vertical) cos of that angle is the horizontal component so you multiply cos of angle x angular velocity for the different angles as it falls. turns out the maximum occurs at 55 to 65 degrees from vertical - I calculated at 5 degree intervals so low res answer. Now this is based on gravity propulsion, no pull rope, no air damping slowing the swing e.g. a log (like the chimney) so it seems about right. So close the log notch at 60 degrees to pop it free. If you change the angular velocity profile the math will find the peak of the curve at a different angle. Just multiply cos angle x angular velocity at angle. The whole principle is that the further it swings down the faster it goes, but the less of that speed is horizontal component - i.e. the part that creates "throw".

An air damped branch laden top probably has a different velocity profile maybe with less pickup at the later angles as the air (square law for wind resistance) has more effect. That would probably raise the angle to 55 degrees or something less than the 60 degree log answer because the cos effect would be more dominant than the lessened magnitude of the angular velocity.

No p-toing has been accounted for. The first half of p-toing is shoving the spar back, taking away throw velocity. If it pops real early you've lost throw velocity and started from a backed up position. If it pops free with the spar sprung back but stopped, you've lost no throw velocity but lost some start position. If the spar sprang back to center as it pops free you've lost no start position and gained some throw velocity. etc. worst case the top is tugging the stem forward for a while before it frees. Honestly, with factors like the rigidity, mass of the spar, length etc a guy would be hard pressed to figure out if he added throw velocity or the top tugged you along if you thought you saw an ideal launch while riding it. There's a physics solution that shows pushing and pulling both occur when a "chimney" falls not on a pivot/hinge but on a friction surface where motion can occur besides pivoting. My knowledge absorption pulled a Homer Simpson when I found that stuff.

The next answer is what if you boost the initial angular velocity and then let gravity do the rest. Bit different equation for the angular velocity curve. Intuitively, the early part of the curve would have higher velocity values ratio-wise than the later angles like 70 degrees, and would interact better with multiplying times cos, so it would make a peak horizontal velocity component occur sooner than the 60 degrees log answer, perhaps substantially earlier. For another time ...
 
The bottom line is that a good treeman Can influence when a top disengages from the spar. In my world the distance between the end point of the pushback and the end point of the forward push is frequently over 10 ft. Combine that with the little bit of throw you can get if you disengage the top during forward movement, and that can add up to as much as a 15-20 ft difference as to were your top ends up. Again, a subtle technique that when needed can be used our advantage.
 
Well, here goes. This https://arxiv.org/pdf/physics/0210033.pdf has the equation for a falling chimney (e.g. the ones that crack apart on the way down) and the angular acceleration is proportional to sine of the angle from vertical. Oddly, the acceleration is inversely proportional to the length of the log but independent of its weight or density. They then say that the angular velocity is proportional to (1-cos (angle from vertical)) with the same odd independence as the acceleration. Once you have angular velocity (vs angle of top/log from vertical) cos of that angle is the horizontal component so you multiply cos of angle x angular velocity for the different angles as it falls. turns out the maximum occurs at 55 to 65 degrees from vertical - I calculated at 5 degree intervals so low res answer. Now this is based on gravity propulsion, no pull rope, no air damping slowing the swing e.g. a log (like the chimney) so it seems about right. So close the log notch at 60 degrees to pop it free. If you change the angular velocity profile the math will find the peak of the curve at a different angle. Just multiply cos angle x angular velocity at angle. The whole principle is that the further it swings down the faster it goes, but the less of that speed is horizontal component - i.e. the part that creates "throw".

An air damped branch laden top probably has a different velocity profile maybe with less pickup at the later angles as the air (square law for wind resistance) has more effect. That would probably raise the angle to 55 degrees or something less than the 60 degree log answer because the cos effect would be more dominant than the lessened magnitude of the angular velocity.

No p-toing has been accounted for. The first half of p-toing is shoving the spar back, taking away throw velocity. If it pops real early you've lost throw velocity and started from a backed up position. If it pops free with the spar sprung back but stopped, you've lost no throw velocity but lost some start position. If the spar sprang back to center as it pops free you've lost no start position and gained some throw velocity. etc. worst case the top is tugging the stem forward for a while before it frees. Honestly, with factors like the rigidity, mass of the spar, length etc a guy would be hard pressed to figure out if he added throw velocity or the top tugged you along if you thought you saw an ideal launch while riding it. There's a physics solution that shows pushing and pulling both occur when a "chimney" falls not on a pivot/hinge but on a friction surface where motion can occur besides pivoting. My knowledge absorption pulled a Homer Simpson when I found that stuff.

The next answer is what if you boost the initial angular velocity and then let gravity do the rest. Bit different equation for the angular velocity curve. Intuitively, the early part of the curve would have higher velocity values ratio-wise than the later angles like 70 degrees, and would interact better with multiplying times cos, so it would make a peak horizontal velocity component occur sooner than the 60 degrees log answer, perhaps substantially earlier. For another time ...

Thanks for sharing that.... which will get the blood pumping to areas to the brain that haven't seen much action since high school trig class.... Even though these threads do get ugly at times the nice thing about them is that they do get people thinking..

To summarize: I think what he's trying to say is I'm right.... LOL

Of course Rico clearly showed in his video that he's right too...

Which just goes to show that there are too many factors involved to make a blanket statement ..

A tree is not a chimney...

For example... the angle of tree at separation is going to be affected by more than just the angle of the notch... it takes some more degrees of fall to break the hinge, which will depend on species, size and shape of the hinge, mass, acceleration and angle of the top, if (and how fast) the cutter keeps cutting , and very importantly if its a humboldt or a traditional ..

Then of course there is size and species of tree, height at which the cut is made, flexibility of the stem, effecting push back, and point of separation during the pendulum movement of the stem...

and as stated the above, Bart's lesson in physics does not take into consideration the use of a pull line ... Anytime I really need to throw a big top, I'm going to use a pull line...
so there are related factors to consider including: how high the line is tied off, the angle of the pull line, force on the pull line, acceleration of the pull, stretch in the line, and mass of the top...


Seems to me that the pull line is going to significantly lessen the effect of push back, which may have been one reason that Rico and I had such different perspectives on the subject... ( that and he's making his topping cuts higher than I have ever been in a tree).... I think the angle of the pull line is going to affect the push back too...
 
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Seems to me that the pull line is going to significantly lessen the effect of push back, which may have been one reason that Rico and I had such different perspectives on the subject... ( that and he's making his topping cuts higher than I have ever been in a tree).... I think the angle of the pull line is going to affect the push back too...

Let’s first define pushback as the backward motion that happens as your top begins to hinge.

Go take a top out of a tall conifer with a serious head lean on it. Go take a top out of a tall conifer that has a loaded up pull line in it. You know what’s gonna happen? Your gonna take a serious fucking ride! Why? Because what is pulled forward must begin moving backwards as the top begins hinging. The further it’s pulled forward, the more it gonna pushback.

I realize most of my education and scars were obtained while working in the woods or rolling around on a bar room floor, but I believe this is what some are referring to as “Physics”?
 
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Funny note on physics,
I scored in the upper 1 percentile in the country on my SAT's in science and physics in high school....but I figured I would do all a favor and keep my discussion as free of physics quotes and math as possible since its bad enough posting as a tree newbie.....A tree newbie spouting physics and trying to adapt them to treework on a tree forum is a guy oblivious to the knowledge of those who deal with those physics in a real world on a day to day basis.
 
Funny note on physics,
I scored in the upper 1 percentile in the country on my SAT's in science and physics in high school....but I figured I would do all a favor and keep my discussion as free of physics quotes and math as possible since its bad enough posting as a tree newbie.....A tree newbie spouting physics and trying to adapt them to treework on a tree forum is a guy oblivious to the knowledge of those who deal with those physics in a real world on a day to day basis.
Unfortunately they didn’t offer physics in 8th grade, which was my last full year of schooling.
 
Physics says this top will clear the target. Physics doesn't know someone put a nail in the tree 40 years ago or that the tree healed over a knot 4 inches deep in the wood that fucked up my hinge. Plus the ground guy pulling the top slipped and a gust of wind came just as the top started moving. But what really did it is when the squirrel jumped out. The force of the squirrel jumping threw everything off. Your going to want to have your lawyer call the squirrel, it was his fault.
 
An age old argument. Do you listen to the man with a PHD trying to figure it out in the lab, or do you listen to the man who has been doing it for decades. Like many things the best answer is often found near the middle of the road, where the sunlight usually is.
 
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Let’s first define pushback as the backward motion that happens as your top begins to hinge.

Go take a top out of a tall conifer with a serious head lean on it. Go take a top out of a tall conifer that has a loaded up pull line in it. You know what’s gonna happen? Your gonna take a serious fucking ride! Why? Because what is pulled forward must begin moving backwards as the top begins hingding. The further it’s pulled forward, the more it gonna pushback.

I realize most of my education and scars were obtained while working in the woods or rolling around on a bar room floor, but I believe this is what some are referring to as “Physics”?


one of the nice thing about making big cuts from the bucket is the feeling you get, post cut, when you watch the trunk shaking violently and you think, thank God I don't have to worry about that anymore!
Blowing a big top on a tall skinny tree into a line with no run to clear some obstacle... When that top slams back into the trunk, the top whips wildly all over the place, you break into a quiet smile..

That's an option you would try to avoid if you had to take the ride...

Similar with the push back, .....................and yes it's crucial to define the terms.. so let's call it push back (for the initial movement at the cut as the top leans towards the beginning if its movement, and the top of the spar starts pushing back) and then "spring return" for the second movement of spar top towards the lay and the entire movement back and forth as topping oscillation.............

if you spring load the top with a line, while it will create more topping oscillation (not good for a climber), the effect of push back is going to have less of an effect on the movement of the top, meaning the top is still going to get more forward movement, as the effect of the pull will outweigh the increased push back... (I THINK :) )
 
one of the nice thing about making big cuts from the bucket is the feeling you get, post cut, when you watch the trunk shaking violently and you think, thank God I don't have to worry about that anymore!
Blowing a big top on a tall skinny tree into a line with no run to clear some obstacle... When that top slams back into the trunk, the top whips wildly all over the place, you break into a quiet smile..

That's an option you would try to avoid if you had to take the ride...

Similar with the push back, .....................and yes it's crucial to define the terms.. so let's call it push back (for the initial movement at the cut as the top leans towards the beginning if its movement, and the top of the spar starts pushing back) and then "spring return" for the second movement of spar top towards the lay and the entire movement back and forth as topping oscillation.............

if you spring load the top with a line, while it will create more topping oscillation (not good for a climber), the effect of push back is going to have less of an effect on the movement of the top, meaning the top is still going to get more forward movement, as the effect of the pull will outweigh the increased push back... (I THINK :) )

In my experience a tagline usually causes the top to rotate more, rather than get pulled out further ... likely due to the fact that you're pre-loading rotational force, as opposed to lateral force, on the top ...
 
A tag line will get the top moving faster into the fall, creating more forward momentum early in the fall..... the whole idea is to get the piece moving forward as fast as possible at release... in the beginning of the fall, the piece (best pictured as the center of gravity of the piece) is moving almost all forward, but slowly.. as the fall continues, the piece picks up speed, which is good, but the movement becomes less forward (horizontal) and more downward (vertical). We want forward (horizontal), not vertical.. There is a sweet spot fairly early in the fall where the piece has begun to pick up forward speed, but isn't moving fast down yet. That is where you want the release (when push back and spring return aren't going to be much of a factor)..

If you watch tree falling with wedges or with natural front lean, they start real slow, and it takes them a while to pick up speed, by the time they start picking up speed, the COG is going more down and less forward than desired for throwing tops.. So the pull line can get a big tree moving faster early in the fall... That's what you want in throwing tops.. after that you want to make sure the force needed to break the hinge doesn't slow the top down as it's building forward momentum... If the top leans out a ways, then stops or slows significantly on a seized hinge, you've lost all that forward momentum you were hoping to use, and the top will just drop like a stone when cut... This is going to be more a factor on tops with less mass and momentum, and species with stronger hinge fibers...

I was trying to use the step cut on the throwing pine top video to allow the line to spring load and have the piece start fast from the get go, once the step breaks and the truck is already moving quickly...

So other factors that might influence the effect of a pull line would be the speed and force of the pull, the angle of the line and the tie off placement on the top relative to the COG ...
 
Unfortunately they didn’t offer physics in 8th grade, which was my last full year of schooling.

Me too Rico, I was midway through 9th grade (Jr high ran 7-9 back then) and they told my parents I was plenty bright and they would pass me if I stayed away from school the rest of the year. At 16 I was on probation and my PO made me take a HS equivalency and then later the next yr the county college had me do the SATs to test my aptitude so I could to try to be accepted....trouble was I got off probation at 18, got a job as a full fledged mechanic and never looked back.
 
Me too Rico, I was midway through 9th grade (Jr high ran 7-9 back then) and they told my parents I was plenty bright and they would pass me if I stayed away from school the rest of the year. At 16 I was on probation and my PO made me take a HS equivalency and then later the next yr the county college had me do the SATs to test my aptitude so I could to try to be accepted....trouble was I got off probation at 18, got a job as a full fledged mechanic and never looked back.
Sorry but I’m gonna have to nip this relationship in the bud bro. I can’t afford to be caught cohorting with fellow felons.
 
A tag line will get the top moving faster into the fall, creating more forward momentum early in the fall..... the whole idea is to get the piece moving forward as fast as possible at release... in the beginning of the fall, the piece (best pictured as the center of gravity of the piece) is moving almost all forward, but slowly.. as the fall continues, the piece picks up speed, which is good, but the movement becomes less forward (horizontal) and more downward (vertical). We want forward (horizontal), not vertical.. There is a sweet spot fairly early in the fall where the piece has begun to pick up forward speed, but isn't moving fast down yet. That is where you want the release (when push back and spring return aren't going to be much of a factor)..

If you watch tree falling with wedges or with natural front lean, they start real slow, and it takes them a while to pick up speed, by the time they start picking up speed, the COG is going more down and less forward than desired for throwing tops.. So the pull line can get a big tree moving faster early in the fall... That's what you want in throwing tops.. after that you want to make sure the force needed to break the hinge doesn't slow the top down as it's building forward momentum... If the top leans out a ways, then stops or slows significantly on a seized hinge, you've lost all that forward momentum you were hoping to use, and the top will just drop like a stone when cut... This is going to be more a factor on tops with less mass and momentum, and species with stronger hinge fibers...

I was trying to use the step cut on the throwing pine top video to allow the line to spring load and have the piece start fast from the get go, once the step breaks and the truck is already moving quickly...

So other factors that might influence the effect of a pull line would be the speed and force of the pull, the angle of the line and the tie off placement on the top relative to the COG ...

What happens when a top first starts going? That’s right, pushback.

What happen if you get the top to disengage very early, as you suggest? That’s right, it disengages as the spar is moving backwards.

Not a good idea if “throwing a top” is your intent.

So while you have been busy with all your hypothesizing, I simply posted some video evidence poking some serious holes in your theory.

Of coarse all bets are off if one was silly enough to hook their tag line up to a truck, rip the slack out of it, and drive off into the sunset going 40 fucking miles per hour. Who the heck would do something like that though?
 
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I never got caught so can we still be friends?
Absolutely, and I like to think we are much more than friends Evo. ;) I didn’t just use my very first smiling face ever on any old joe smo, bro.
 
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