OK CLB and Davey If I may please let me point out a few things about using RC throttled engines and the ways of actuating those throttles.

Using a throttled engine will allow you to perform maneuvers hereto for only just dreamed about. First of course the touch and goes that can be for an entire flight if you like and is a joy.

Next straight line taxi for any distance is possible. Yes before I was in this chair it was a joy take off and fly at one end of the runway then land and taxi for the full distance of the runway then take off agine on the opposite end. This can only be done with the over the wire or RC systems and it was a simple matter to walk along with an occasional tug to make small corrections and control speed with throttle. The old three line (or more) could not do this because of the intermittent slacking of the lines.

OK another advantage of using an RC engine is just as Mikeainia pointed out there is no need to stock and transport special fuels beyond your normal RC fuels.

Now lets talk about the control systems if you use a throttle (or more). I used the Bill Young three channel over the wire system for about fifteen years. It used a custom trigger grip along with other switchs and trims. This system at the time was wonderful for me and I love it however it does have problems that is endemic to any over the wire system. First that trigger which is what every body wants is for me a bad idea being difficult to make precision throttle changes while at the same time controlling the airplane. After all those years I still dislike a trigger grip for throttle.

The next problem of any over the wire system is first you need insulated flying line and the two electronic wires that attach to each end of the lines are a weak point and tend to get beat up and sometimes fail leaving one with a very long flight but not by choice. Set up of these special lines are time consuming although not nearly as bad as the old three line (and more) systems. I grew to dread the set up time.

Walla, the advent of 2.4 now is wonderful and we can use the systems freely and at our RC fields if we desire. Setup time is as fast almost as just flying ordinary two line and I do not have to use that pesky trigger grip. There are no wires to hook up with plugs.
I use an elderly Hitec Prism 7X with 2.4 module with a matching receiver and a HS 81 servo to actuate the throttle. The power is four cell 270 mah pack that is quite small and seems to last forever.

On to the best part I did a small mod to the Tx and bonded two hooks to the sides of the unit about where one formerly would have gripped the trx. Then just using an ordinary neck strap the tranny is worn around my neck and hangs in front with the sticks pointing toward the airplane. Using my left to fly the airplane its far easier to use my right for the throttle stick. .

I will try to get some pics up in a few.

John