RE: DF Hawk \ Turbax 48 fan
I had the JHI Hawk with Turbax and K&B .48. Flew fine... if you're going off grass then yes you do need to give it some time to build up speed. If you're going off a hard surface then no problem. If you don't have an engine yet, I'd try and get the K&B 48... the thing is a monster. They're hard to find but out there. Check with JHI. If not they have the Os46.
The key with either engine is following Larry Wolfes instructions for setting up the pipe and use his recommended fuel mix... ie. use a sport fuel with 15% nitro 18% oil and add 1 oz of Turbine oil to the gallon. “Jet Fuel” like JetCat with their 23% oil combo is just too much for the 46/48 class engine. Use Larry’s mix. I use Mobil 245 Turbine oil. It tends to cause any castor to separate but you just need to shake the jug when you head out to the field. The 245 is also photo reactive so it turns your fuel very dark after sitting in the sun. No problem. I've use this fuel mix in my 48's since I got them... years... plus I also us it in my .52 to .91 4-strokes. They love it.
Back to the .48.. set up per JHI... I don't even tach 'em anymore because they're always turning up over 26k usually more like 27. It really is a set and forget system... I just do the pinch test to check the mixture before buttoning up to fly... compensates for the current atmospherics and everything. The OS 46vxdf is about the same. Check out JHI’s website.
My Hawk died due to dumb thumbs... I'm currently flying the .48 in one of JHI's A-7D's... Sweet airplane.
Craig