I remember reading somewhere on the net that Wernher von Braun thought
that all man-rated rockets should be liquid and not solid rockets
because solid rockets can not be turned off in case of failure.   I
want a URL(s) for that quote or claim.
Some other keywords: abort, human, felt

Hello vincecate

Thanks for an interesting question.
I've found one article confirming what you remember:

"As an aside, Von Braun had said that no human should ever ride on
solid rockets. They were just too dangerous. One in twenty-five blew
up due to defects. They could not be stopped once lighted and thus had
the potential for a major loss of life."

This is part of a discussion of the Challenger disaster which is
assigned reading for a class at MIT under the heading: "Space Shuttle
Development: Seeds of the Challenger Disaster".

"The Challenger Disaster", page 4
sub-heading: 'The Technical Design of the STS & the path to a
segmented solid rocket design'
http://msl1.mit.edu/ESD10/block4/4.3_-_Challenger.pdf

To read this you will need Adobe Acrobat Reader on your computer. It
can be downloaded free from:
http://www.adobe.com/products/acrobat/alternate.html#505 

Alternatively, Google has a stored version at:
http://216.239.57.100/search?q=cache:mqHWqw3zbZ8C:msl1.mit.edu/ESD10/block4/4.3_-_Challenger.pdf+%22von+braun%22++said+OR+thought+liquid+solid+human+OR+manned+danger+OR+dangerous&hl=en&ie=UTF-8


I hope this is helpful. Please let me know if you need any
clarification or if the links malfunction and I'll be glad to assist.


Regards - Leli



searches:

I tried various approaches leading to nothing - this is the one that
worked:
://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=%22von+braun%22++said+OR+thought+liquid+solid+human+OR+manned+danger+OR+dangerous&btnG=Google+Search