First, appologies for top-commenting, but Bob's latest is reproduced,
with some snipping, below.
Bob, I made a fundamental error in my analysis, which was corrected
in a later post....the load on the winch may well be less than
a ton. Neglecting a 90' lever arm will do that to a calculation.
You may be able to get away with some added internal lateral braces
in the attic, to handle the load.
Secondly, you may be on to something with the roof support plan.
You WILL want to calculate the vertical loads on the roof, though,
before you go forward...and given my prior track record at quick stabs,
I'm not going there. And surely not at 5 am, again!
N2TK, privately, has indicated that he has about 1750 lbs load on the
winch in his w3gm falling derrick 45G system. That has some real
advantages, which you may want to explore with him, one on one.
Tony sent me some .jpg's, which I'd be happy to forward to you, if
you're interested.
Thirdly, I have a folding mast to boom plate design which I implemented
in my 45G foldover, which I'd be happy to share with you.
Fourthly, and this IS critical...you MUST have guy anchors for your
side guys AT THE SAME HEIGHT, and you must 4 way guy the tower.
Otherwise, there's no hope. A laser level is necessary to assure this.
Having set aside the structural load issue, my personal concern would be
the proximity to the house. Once you've got your guys in place and
tightened,
it'll probably be ok...but that first time, when you're working with
calculated
guy lengths....could be squirrely. Suppose you're a foot short, and it
doesn't
go all the way up? How do you recover/adjust?
So...my suggestion is, take a look at n2tk's approach, and see if you can
brainstorm from there, to accomodate your site issues.
N2EA
Message: 2
Date: Wed, 1 Jun 2005 21:12:02 -0500
From: "Bob Gates" <regates@kingwoodcable.com>
Subject: Re: [TowerTalk] "House" Method of Raising a Tilt-Over Tower
Evening All,
I'm beginning to get the idea that some, read that all, think this is a most
stupid idea. But let me answer some of the other suggestions before asking
some more questions.
I plan on a pair of phased 4-ele Steppirs and a pair of 2-ele 40m yagis.
The two lower antennas will be installed on TIC Ring Rotors, which have
hinged boom cradles. After my wife gets used to seeing all this, I'll be
adding verticals and wires for 80 and 160.
Now on to the main issue. I think all of the comments could be summarized
by Jim Jarvis who said "Don't do it Bob!", and Uncle Steve who started out
with "HOLY CRAP!" What am I supposed to make of these innuendos?
Are you suggesting I try something a little different? Actually, I had a
"Plan B". Now stop that groaning! Plan B was to make a saddle to set over
the peak of the roof using two sections of 25G, one on either side of the
peak. Would also reinforce the roof on the inside. Then I would back a
wrecker into my driveway, run his cable over the saddle, and attach it to
the end of the guy wire attached at the 90' point on the tower. And, once
again, just pull that puppy up. Neat huh? Stop laughing! The load on the
roof would all be downward, and the cable/guy would never get close to
touching the eave of the house on the South side. The tower would be laid
out horizontally and all booms would be turned horizontal as the lift is
started.
On-the-other-hand, Uncle Steve scared the pee out of me with the
possibilities of what could go wrong. I can just imagine the torquing that
could occur if the wind picks up, and others have obviously had more
negative experiences than I have thought out. So back to the drawing board!
Actually, it's back to hiring a professional, if I could only think of
someone who does this kind of work. :) Thanks all for your comments and
ideas, much appreciated. And I WILL get this tower up in the air!
73, Bob W7BJ
N2EA
jimjarvis@ieee.org
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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