RE: Reaction 54 Jet Kit
I made a tunnel from three slabs of sheet steel, joined at the corners with angle iron. Weight of the hot box is 15, maybe 20 pounds. I've felt it after starts, and it's definitely warm. I thought about using a stove pipe, but it would either need legs or somebody holding it during startup. In the end, I thought the heavier tunnel was the best way to go because it could just sit there with no concern about being blown away. If you use a pipe, I suggest using as large a diameter as practical, and make it heavy enough that it can just sit there during startup.
With the Kavan brake activated, it should take quite a bit of force to turn. Not all your strength, but not fingertip pressure either. That's as much as I can quantify it. I actually added a dab of grease to the friction plate to help it turn easier. Maybe the idle thrust of the P-60 is higher - My model actually rolls to a stop fairly quickly on pavement without braking.
Bruce