[alma-config] Transporter issues

[Al Wootten]

This email was in my box when I returned, and did not propagate to the list.

Al

Date: Fri, 11 May 2001 12:05:15 +0200
From: Maximilian Kraus <mkraus at eso.org>
Organization: European Southern Observatory
X-Mailer: Mozilla 4.75 [en] (WinNT; U)
X-Accept-Language: en
MIME-Version: 1.0
To: Leonia Kogan <lkogan at zia.aoc.NRAO.EDU>
CC: torben.andersen at astro.lu.se, alma-config at zia.aoc.NRAO.EDU,
        pnapier at zia.aoc.NRAO.EDU
Subject: Re: move antennas starting from
References: <200105101809.MAA19842 at bonito.aoc.nrao.edu>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Hallo Leonia,

I cannot definitely say, if 15 m bewteen antenna pads is enough for passing through,
because I have no drawings of the US antenna foundations.
The transporter transporter concept I'm working on has a vehicle width of 7.3 m, and
we should specify a width limit at 7.5 or 8m.
The foundation of the EU antenna has a diameter of 6m(t.b.c.) , leaving a gap of 9m
between 15m spaced pads, that's o.k.
The US antenna foundation has a diameter of 11m(t.b.c.) leaving a gap of 4m which is
too small. But this dimension just is taken from an assembly drawing and is not
confirmed.

If we allow to drive over pads there is no limitation, and your proposed sequence is
o.k., in fact antenna removal can start from almost anywhere.

The R150_NOROAD.6 configuration provides enough removal pathes with a minimum
distance between antenna pads of ca 18m. Critical, but possible  are antennas 24 and
25.
18m minimum gap would require a max pad diameter of 9m, assuming a vehicle width of
7.5m and 1.5 m safety margin.
Consequent removing from inside out is not possible. e.g. 33 needs to go between 57
and 58.

I'm working also on an alternative transporting concept using adapted cranes and low
loaders. That concept has a width < 4m, but has some drawbacks (cost, more time
needed etc).

Is there a specific operational or scientific advantage of the concept 'eating
antennas from inside'?
How/when to address the problem of access to a broken antenna? If we don't have good
access (e.g. removing/exchange  possible within one work-shift) we have to adapt the
maintenance philosophy accordingly. Presently we prepare for easy and quick
transport of antennas to OSF, to reduce the work at high altitude.

max

Leonia Kogan wrote:

> Hi Max,
>
> Thank you very much for your response.
>
> I'd like to clarify my idea of eating the configuration from inside.
> First of all I want to lay aside the problem of repair of antennas.
> I have excluded the requirement o to have an access to any antenna at any time.
> Let me discuss this requrement later.
>
> Now lets consider the R150_NOROAD.6 configuration specifically.
> I do not consider the two circles as roads. I consider only one road (30m width)
> leading from the right to the inner antennas 1, 6.
>
> I see the following sequence of the antenna transporting:
>
> 1. Got to antenna 1. I think(?) there is a good access to the antenna 1.
>    take it and remove it.
> 2. Do the same job with antenna 6
>
>    Now we have pads 1 and 6 without antennas and the spase between the
>    centers of the pads 1 and 6 >=15m
>    Here is the crucial point: Is this space enough to pass transporter
>    with antenna. I thought it is enough. If not the following does not work.
>
> 3. Pass through the gate between the pads 1-6 to the center and pick up
>    the antenna 3. Return back with the antenna 3 passing through the gate
>    between the pads 1-6.
>
> 4. Repeat the item3. with antenna 4, 2, 5
>
>    Now have the six inside pads without antennas. The distance between
>    the pads is >=15m. Again if this space is enough to pass
>    transporter with antenna, we can get the access to the antennas of
>    the second circle passing between the epty pads of the inner circle.
>
> 5. Having finished the second circle we have epty pads of the second
>    circle and can start removing of antennas of the third circle.
>    (again if the space 15m between the empty pads is  enough to pass
>    transporter with antenna)
>
> An so on.
>
>    So the crisial point is:
>
>    Is the space 15m between the empty pads enough to pass
>    transporter with antenna?
>
> Thank you
>
> Leonia
>