[pianotech] flipping a truck

[Ron Nossaman]

Israel Stein wrote:
> Something has been bothering me about this. Wouldn't the center of 
> gravity on a piano mounted on a flipped truck be quite a bit higher, 
> making the whole thing less stable - if force is applied at the wrong 
> place in the wrong direction? Granted, a tripod (which is what we have 
> here) is inherently the most stable configuration, but suppose 
> sufficient upward force were for some reason applied at one of the legs 
> - wouldn't it be possible for the whole thing to tip over along the line 
> formed by the other two legs - given such a high center of gravity? Now 
> I know that this is not likely, but we have here a bunch of ignoramuses 
> doing unpredictable things with a piano...

I'm forever amazed that a profession so filled with - 
recovering - engineers doesn't swamp this sort of question 
with highly educated answers, all in absolute agreement to 
four decimal places. But in the continued conspicuous absence 
of experts, I'll take a non-pedigreed stab at it.

In my world, the center of mass of an assembly has to be 
outboard of it's support for it to tip over. So far, I haven't 
run into an instance where that presumption hasn't proved to 
be a practical guide to preventing things from falling over. 
If a piano on a standard truck has to be tilted at 45° 
(arbitrarily chosen) to tip over, then a piano on a flipped 
truck, supported at a higher altitude, would tip over at a 
lesser degree of inclination, say, 40° or so. Even if it were 
30°, which is what doing the math instead of speculating is 
for, it would take a pretty spectacular idiot or committee to 
make up the difference. While I have no doubt whatsoever that 
such spectacular idiots and committees exist out there in vast 
numbers, I submit that the difference between a 45° tip point 
and a 40°, or even 30° (math verification pending) is way too 
far past the idiot threshold to be guarded against by a mere 
5°, or even 15° (pending the math) difference in an 
inclination angle already way past rational (math verification 
impossible). But then there's the question of the legs 
breaking before the optimal idiot inclination tip point is 
achieved, thereby robbing the participant(s) of their due 
glory and immortality, and screwing up the vector calculation.

But Then, I'm not an engineer,
Ron N