OK... some real numbers.. off the Rohn BX data sheets which I found on the web. Whether or not this is a tower anyone would actually use, or contemplate guying is sort of immaterial. It's representat
Jim, Thanks for going through those calcs, it's much appreciated. Just a couple of questions: Why did you choose 60% guy anchors instead of the commonly recommended 80%? I agree though that 60% is pr
To make the math easy. 60% out is actually about 31 degrees.. I just rounded to 30 degrees, so sin(30) = 0.5, cos(30) = 0.866 If you want to go out to 80%, the angle becomes 38.6 degrees sin(38.6) =
I can't quite get my head around this. Without knowing how much the top end moves, or the middle bows, how can you know the bending moment? If the top does not move at all, and the tower is perfectly
Yes, there's still a moment. If it's perfectly rigid, there's no deflection. A moment is a just a torque (i.e. a rotational force, as opposed to a translational force, like a shear or compression or
good model for aluminum towers here that would would collapse and strength Nearly all self support towers are considerably wider than guyed towers where the stress is maximum, so if anything the guy
W6RMK concluded, in engaging K8LX: Probably another good point, right along with N4NM's. Trying to stay away from K8LX's largely (I believe) academic point that guying has the potential to increase t
And yet you said just above that the moment would be the same in a pin/pin support. If I had three bathroom scales I'd go do a little experiment, but I don't. So let me ask you what I'd find if I did
BTW, I realize you would need a little more info to give actual numbers - what I'm really interested in is whether all three scales would read the same or not. I would expect them to read the same, i
OK, good. Here's where I'm unclear. Let's say, in addition to the 10 lb load at the top, you put a 10 lb load in the middle of the tripod. What do you see on the scales? Steve K8LX __________________
Here's where I'm unclear. Let's say, in addition to the 10 lb load at the top, you put a 10 lb load in the middle of the tripod. What do you see on the scales?>> Steve, Getting our arms around a comp
Tom, I agree with all that, and I think everyone who has been bewildered by the Don't Guy mantra does too. Still, I'm confused by the base moment in Jims calcs and would like to get to the bottom of
....because the tower can deflect and the guys are at the top. That will lift some leg(s) and compress others more. My point is it never seems to get worse than without the guys. 73 Tom ____________
Yes of course, but he came up with a number WITHOUT knowing the deflection. That was my whole point. It seems to me that if you hold the top still, and the middle does not bow, then you have pure she
Brett mused: bunch of this tower shipped over & put some up myself. Why bother spending more money when I can just add guys, more sections & a lot more antenna? This stuff is much more than the great
NM5G added: <snip> I'll do the climbing. I may no longer be willing to face away from the tower in order to reach a loose bolt out on a boom 70m up & I doubt I would be willing to do any of the thing
Think of the problem as a single horizontal 10 ft long beam, rigidly attached at both ends, for the mean time. Let's just consider the forces from the weight in the middle The beam's attached firmly
I hope that everyone knows the BX series is only designed to hold a beam with a boom of NO longer than 10 feet. Guyed or unguyed. There have been horror stories of those who tried longer beams such a
Jim, OK, I thought about that for quite a while (not all day though - I actually worked today!). Went to a couple of web sites that seemed to offer free physics lessons. Drew some diagrams, got a hea
BTW, the page I stared at the longest was this one: http://structsource.com/analysis/types/beam.htm _______________________________________________ See: http://www.mscomputer.com for "Self Supporting