Use Google Docs Viewer to open document from rails app (paperclup, cloudfiles)

Question

In our rails app we use paperclip to save files to rackspace cloudfiles. We want to allow users to VIEW the files without needing to download them and use a program on their computer. We have found https://docs.google.com/viewer which looks good for the job

We have the following method in the controller:

  def view
    att = Attachment.find(params[:id])      
    redirect_to "http://docs.google.com/viewer?url=#{CGI.escape(att.file.expiring_url((Time.now + 60.seconds)).gsub(/^http:/, "https:"))}" 
  end  

This generates the following url:

https://drive.google.com/viewerng/viewer?url=https://snet-storage101.syd2.clouddrive.com/v1/MossoCloudFS_4a360775-1b68-41f9-884f-e62e7567af25/container//attachments/files/000/003/488/original/AK-_Time_Recording.pdf?temp_url_sig%3Dd36797290b85f2dcd752xxxxxxe6a08951ad%26temp_url_expires%3D14xxxxx7408&u=0

The google docs viewer then tells us:

• Apologies, there is no preview available.

I suspect it has to do with the "temp_url_sig" and "temp_url_expires" parameters that are appended to the pdf file url.

Any ideas how we can get this to work?