setting file encodings transferring data via send_data in Rails

Question

Hi,

I'd like to transfer a UTF-8 encoded string to the client, rendering the string as a text file (in my case a v-card) using

send_data str, :filename => "file.vcf", :type => 'text/html; charset=utf-8'

Unfortunately the submitted file doesn't contain any encoding information and address books open the file in the default encoding of the operating system of the client.

Is there a way to set the encoding information of the file to be transferred?

Thanks for your help!