Some pianos extend downwards by a further 5th. Some upright pianos only reach up to A7
The piano in an orchestral context may be viewed as a percussion instrument or it may be treated more melodically. The important thing to bear in mind is that it has very little sustain. All the sounds die away more or less rapidly. So piano notes tend to get 'swallowed up' in the wash of orchestral sound very quickly.
Toy pianos are occasionally used in orchestral compositions.
The Orchestra: A User's Manual is a free resource and will remain so. It still receives between 8,000 and 16,000 unique visits per month from all over the world. See the testimonials. Thanks to all the donations, I have been able to create this responsive re-design. But the movies and sound clips recorded in 2004 do show their age. I would really like to re-record everything and add many more techniques, especially for solo and ensemble writing. I estimate this will cost around £30,000. If you know a source of such funds, please contact me: a.hugill [at] bathspa.ac.uk