No, I do not believe that it is unethical to perform scientific experiments on voluntary human participants. If the people are volunteering for the experiments there should not be an issue with the situation. Humans donate their bodies to science everyday, this may be the only way that an individual will have to contribute to the world. Every situation is different and should be treated as such.
It is not unethical to perform scientific experiments on volunteers. As long as the volunteer has been fully informed of the risks and side effects of the experiment they are being exposed to, and, as usually happens, the experiment has been vetted and passed by a panel of other scientists, then it cannot be called unethical.
It was unethical when the government experimented on military personal to perfect LSD. They did not tell them all the side effects they would be experiencing. Of course, the scientists probably did not know either. That is besides the point, once they found out, they should of stooped the program. I believe scientist are not allowed to this anymore, unless they give full disclosure as to what their test subjects are in for.
It would not be unethical to perform scientific experiments on voluntary human subjects. It would have to be undeniable, however, that the subjects were rational, lucid, and capable of making the decision to participate. Some mentally incapacitated individuals might be persuaded to volunteer but not fully understand what they were agreeing to. If individuals willingly agreed to the experimentation and were of sound mind, then it would not be unethical.
I do not see anything wrong with performing scientific experiments on individuals that are willing participants. I think that as long as there isn't anything going wrong with the legality of the process, I think that people should have the right to participate in such experiments. I think that it benefits mankind.