A necropost response, but I'm wondering the same thing too. Orbiter is sorely lacking an up-to-date Project Mercury. IMO, in regards to the Redstone and Atlas rockets, I bet a velcro alternative could be made from those meshes, so I'll give that a try.
---------- Post added 10-04-14 at 04:44 AM ---------- Previous post was 10-03-14 at 09:03 PM ----------
So basically all I've done is taken the meshes for the original Redstone addon and made a velcro rocket out of it while taking into account the proper dry mass (3125 kg), max fuel mass (28440 kg), Isp (~2107 m/s), Max Thrust (350000N). Not entirely sure if those values are correct as I believe I might have gotten them from different variants of the Redstone, so consider that as a starting point in my research but it was certainly nice to handle a Redstone on Orbiter again. I've still got to find the IspSL for the old Redstone, so if anyone can help there that'd be appreciated. Also added some added bump maps for anyone using D3D9, I'll see if I can make my own higher resolution textures. Will also make and add fairings.