[TowerTalk] [Bulk] Re: Fwd: Aluminum towers -- can you really "walk one up"?

[Grant Saviers]

nope,  as you walk in, more of the weight of the tower is behind you.  
Another way to think about this is what size torque wrench would you 
need to raise the tower if it was attached to a hinge bolt?  Ans: HUGE.  
A 300# 85' tower needs a torque (moment) of 300*42.5= 12,750 ft-lbs to 
move it just up from horizontal. Assuming the sections are uniform, we 
can use a mass one half the length, so with a tapered tower it will be 
less.  Or you can weigh each section, and use the distance to eacg 
section center when assembled and add up the moments for a fairly 
accurate approximation of the initial raising moment.

Yes, the lifting load at the end is only 1/2 the weight (less for a 
tapered tower), but as you walk in the force needed increases.  At 45 
degrees a little geometry will show where you will be trying to hold the 
tower up. Then calculate the load - from the 12,750 ft-lbs of moment 
(actually not quite accurate since the changing geometry helps a bit).

A 16' 2x4 has very poor buckling strength, perhaps a recipe for disaster.

A walking or fixed derrick is the way to go.

Grant KZ1W

On 3/9/2015 6:29 AM, Patrick Greenlee wrote:
> Say what?  If the tower were not tapered (lets look at a simple model) 
> and you picked up the top then you would support 1/2 the weight and 
> the ground via the hinges would be holding the other half of the 
> weight. The higher the top of the tower goes the greater the portion 
> of the weight is held by the ground/hinges until when vertical the 
> ground holds all the weight.
>
> Buy a 16 ft 2x4 and either notch one end and apply duct tape to secure 
> it to about 16 ft above the tower base or otherwise secure it with 
> wire or...
> Then as you lift the tower the 2x4 can take the load while you rest, 
> change hands, take a break or ... Once the tower is lifted so high the 
> 2x4 is not securing the tower very well grab hold of the 2x4 and use 
> it to push on the tower.  The increased leverage pushing at the 16 ft 
> level rather than at your head height or so will make a considerably 
> easier time of it.
>
> Archimedes said something like given a lever long enough and a place 
> to stand he could bend the lever (move the Earth) or some such.
>
> Patrick    NJ5G
>
> On 3/8/2015 11:45 PM, Richard (Rick) Karlquist wrote:
>> On 3/8/2015 5:36 PM, Hans Hammarquist via TowerTalk wrote:
>>
>>> If you don't put to much heavy stuff on the tower before you walk it 
>>> up it should be OK. Just for your comparison, I have an 85 feet 
>>> aluminum tower and the total weight of the tower, empty is 300 lb. 
>>> It's tapered so the heavier section are at the bottom. No, I didn't 
>>> walk this tower up but I easily carried around the top 40 feet 
>>> during the assembly of the tower and could, probably have raised the 
>>> by myself as a 40 foot tower, had I done that.
>>
>>> Hans - N2JFS
>>>
>>
>> I made some calculations and determined that the
>> force you have to apply to a 40 foot tower of
>> uniform cross section with nothing on top works
>> out to 1.7 times the weight of the tower.  And
>> you have to be able to apply this force using
>> one hand at a time while you "walk".  It all
>> depends on the weight of the tower and the
>> strength of the walker.  Can you hold an 85
>> pound barbell over head and pass it back and
>> forth between your hands?  Then you can walk
>> up a 40 foot tower weighing 50 pounds.
>>
>> Rick N6RK
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk at contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>