Originally Posted by
CrimsonEclipse
I'm curious about vibration on the DeltaHawk.
It's a 4 cylinder (and soon to be 6 and 8 cylinder) two cycle engine. It fires twice as often as a four stroke (virtually every other piston airplane engine except ultralight). I'm going to guess it will have far lower vibration than a 4 cylinder Lyc.
Now all you have to do is have locking fuel caps and monitor every fueling to prevent a Jet A/100LL/100UL mix up. You just KNOW it will happen.
It already has happened many, many times. One plane was fueled with Jet A when the line boy saw that it said "turbocharged" on the cowling. When asked how he got the big Jet nozzle in the small gasoline opening, he said that he had to go very slowly to get it filled up ! Plane crashed.
Cessna 441 and 421.... plenty of screw ups there. Aero Commanders (didn't Bob Hoover once get Jet A in his piston plane?)
Another question is if the turbo and super charger will actually make it to 2000 TBO. Will it require a 2 minute spin down like the 421/414?
It's a liquid cooled engine. Based on the pics, the turbocharger is not liquid cooled (Turbonetics on the turbo casting is a southern California company that sells turbochargers for performance cars). So, will probably require a cool down, like any metal tool that operates at 1650F, and is then exposed to something significantly less. So, who knows. Even if it doesn't require a two minute cool down, the FAA might require it.
Turbochargers are VERY simple. The only moving parts are the impeller wheels and the common shaft they are mounted to, and the bearings. So, what fails? The bearings. Why? Look at that filthy oil those bearings are exposed to. Imagine if a clean burning engine with no TEL (not exactly a trait of diesel engines) was using state of the art synthetic motor oil to lubricate those bearings?
The other turbocharger failures are junk going through the impellers. With no valves to break off and get ejected through the turbo, and with a good air cleaner on the intake side, and a good clean oil, I think the turbo has a greater chance than with an air cooled, carbon deposited, soiled dinosaur oil engine.
The supercharger will probably not go to TBO based on the belt drive. That will probably need to be replaced (with a prop removal $$$$$). Also, not crazy about the same belt running the alternator, because now a seized alternator will take out the supercharger. Also, no current room for a belt driven air compressor for a/c.