RE: What turbine to use for the Yellow A-4 Skyhawk??
John,
Before you invest in a turbine you should think about not only this plane, but what other planes you could use it in the future. If this plane gets wrecked or you sell it what would you do with the turbine? A 13-14 lbs. thrust engine is more versatile because there are a lot more airframes you can use it in.
I just took delivery of an Artes Bee and am very impressed with it. The JF-50 Super Bee is slightly bigger than the Wren 44 and slightly smaller than the P-60, and it puts out 14# of thrust. In the A-4 you could dial the thrust down to 8# if you wish and its fuel consumption will be the same as the Wren 44. Later on you could use the Artes in a larger airframe.
All three are good engines and the companies all have good reputations for service. The Jetcat can be serviced in the USA, Artes either in Florida or Mexico City, and the Wren needs to be sent to the UK for service. For the same money I'd go with the Artes. Here's a comparison from the respective manufacture's websites:
MW44 8# thrust 2.95" diameter 1.7 lbs. with starter $2,495 (full autostart)
P-60 13# thrust 3.25" diameter 1.9 lbs. with starter $2,495
JF-50 14# thrust 3.15" diameter 1.9 lbs. with starter $2,495
Joe