First off, I am using Robart 615 since a buddy in our club is using them in his Cat without any problems. The retractable tailwheel is my creation. I manufactured it for my H9 P-47 and it turned out to be a tad too small. So I decided to use it for my cat which is the perfect size for it. The little gear doors on my mains are hinged but not hooked up to close with the main gear doors, yet. I guess I am going to use simply small rubber bands to do that. It does not take much to close them. Now, for the tailwheel am building split gear doors as well. It will be a little bid more tricky to close them in sequence with the tail wheel going in, but it's possible. I will post more pix once I am done. How far are you, big bird?