The Ultra Sport has been in constant production for 25 years and clearly its flight characteristics have a lot to do with that. The Ultra Sport is groovy, flies on rails, feels locked-in, has neutral stability and it is fast and smooth and forgiving. It is not a 3D flyer or a fun fly machine, but for sport pattern type flying, there is nothing better. Unfortunately it is only available as a kit, and it is an old style kit that involves carving and sanding those nice curves.
Now Hobby People has introduced an ARF called the Taipan that looks like an Ultra Sport clone. Unfortunately, in it's stock form, it will not fly like an Ultra Sport. I must admit that I have not flown a stock Taipan, but there are four major differences between the Ultra Sport and the Taipan that will alter the Taipans flight and ground handling characteristics. Maybe someone else will try it stock to see how much it is affected.
To make the Taipan into a true substitute for an Ultra Sport, I needed to do the following easy mods: (Detailed in my earlier posts.)
- Hobby People took the dihedral out of the wing. I put it back in.
- The Taipan has a "battery support floor" in the tank compartment. I removed that so that the center of the tank would line up with the carburetor.
- The Taipan's main gear mounts put the wheels too far back. A simple spacer cures that.
- Using the dual elevator servo option on the Taipan would not allow the travel of the two elevators to be properly matched. I used the single servo option, which requires making and installing a music wire joiner.
The stock Taipan, with less dihedral and mis-matched elevators will not sustain level flight or respond accurately to control inputs. It will have a tendency to roll off one way or the other in upright flight or when pulling or pushing elevator. The higher tank mounting will make the engine run leaner under negative Gs than it does under positive Gs. And the main wheels sitting too far back will give the airplane a tendency to nose over.
I spent this morning flying my modified Taipan, and it does indeed fly like an Ultra Sport. It is groovy, stable, smooth, fast, forgiving and all of the things I said above about the Ultra Sport. It is very fast at full throttle, but it will slow down to walking speed for landings. It will not tip stall. It will fly hands off from one end of the field to the other, upright or inverted, without turning off course. My engine runs are consistent and it does not want to nose over while taxiing. It does big round loops and linear rolls. It makes me look like a better pilot than I really am.
It is a bit nose heavy with the recommended CG and the only trimming I had to do was a few clicks of up elevator to compensate. I liked the higher rates that I set in the last post better than the lower recommended rates.
I am going to call this project a rousing success, and I will have a ball with my Taipan until the covering comes off, which won't be very long for that shelf paper. Then I will recover it and fly the heck out of it some more.
Thanks to RCKen and all of the Ultra Sport Brotherhood for letting me post this project here. I hope it has been helpful, or at least entertaining.