Cool yes
RV8RIVETER said:
I have a 200hp Lycoming and am leaning toward an MT, for weight and smoothness reasons (coolness factor doesn't hurt either
). Does anybody out there run a Lycoming IO-360 angle valve and a MT prop? If so, what do you think of it? Thanks, Wade Lively-8 finishing
Wade if smoothness and coolness is the most important than by all means get a MT prop. I assume your question is based on 3 blade MT and another Brand. Other brands of composite props are the Whirlwind and Aerocomposite.
Smoothness: MT props are smooth because they are made of wood cores. Wood is "God's Composite" and has great damping qualities. The other composites have stiffer cores and construction so they will not be as smooth in general. Metal of course will buzz, but some of the other stiff composite props are no smoother. In fact all Lycomings shake a little and a prop can do only so much. IN the end any wood prop will be smooth regardless of number of blades. If I hear Turbine smooth again about the MT I will scream.
Cost: Hands down winner is the Hartzell and Van's kit is designed around it. The Blended airfoil Hartzell is also the hands down fastest constant speed prop BAR NONE. This was proved in a controlled Fly off Van did a year or so ago (results published in the RVator). Three blades are the worst. The only reason to go three blades is if you have high-speed aircraft (mach +.6) and or 500-2000 shaft HP engine. The multi blades reduce blade loading and slow tip speed, which has a side advantage of less noise. For a 200 hp RV, 2-blades are plenty. Any composite prop is going to be from a small company and service will be harder to get and more expensive. In the case of the MT you may have to send it to Germany to get fixed. The down side of that is shipping and cost. A hartzell can be fixed at hundreds of shops around the country at a cheaper cost. Also remember you MT is made up of many parts bonded (glued) and screwed together (Wood core screwed to metal hub, wrapped in composite and an erosion guard bonded to the leading edge). A rock dent / chip on a hartzell (solid aluminum) can be fixed by you on the plane with a file. The MT with a dent or loose erosion strip might need an expensive vacation to Germany, so you can't afford to go on your vacation. The only down side is I am not sure the blended Hartzell is ready for the IO-360 angle valve 200hp yet. Call Hartzell, that is the one I would get, since it is much faster and cost way less. Even the standard Hartzell HC-C2YK/7666-4 is faster than any of the 3 bladed props by a wide margin and faster than most if not all the 2 bladed composites. The HC-C2YK is cheap and widely available.
Performance & Speed: Look the air does not care what your prop is made of. The fact is the thinner the blade surface the better. Metal Hartzell's have thin airfoils and are as efficient or more than any composite, which tend to need to be thicker due to construction. Again the standard C2YK/7666 is a great prop and available. The blended is the way to go on the 180HP and Hartzell may have the blended airfoil model out for the 200HP now. The Hartzell props where several MPH to +10MPH faster than other props.
Coolness: MT or WW or AC, White, two, three blades cool. To me cool is going faster and with out spending 4 to 5 grand more. The Hartzell can get a fancy custom paint or color as an option. The MT is better here. However at least Hartzell has done the testing to show the fatigue life, which is more than most will fly in a life time, if they stay out of the yellow RPMs.
RPM Restrictions: Yes the HC2YK has a range of RPM?s to avoid. The Hartzell Blended does not have a RPM range limitation. The blended airfoil model does have a single point power or rpm restriction but no range, depending on if you have EI or FADEC. These restrictions do not affect normal operations.
Weight: Nothing new here, the metal Hartzell weighs more. For most RV?s a little weight on the nose is good, especially the RV-7 and guess the RV-8 is the same. My RV-4 has a Hartzell and solo full fuel I was near the front CG, however with passenger plus bag I could load to gross and not exceed the aft CG. A light prop would cause a aft CG problem with passenger and bags.
THE CHOICE
With everything considered performance, maintenance, repair, smoothness and coolness, I would buy a Hartzell. BTW you can have your Hartzell custom painted at the prop shop to match the plane or have wild patterns.
Coolness and Smoothness are your prime interest at loss of performance and at a premium price get a MT. Before you buy a MT ask what shop will do repair and maintenance (warrantee work) and what level of repair can be done. Who pays for shipping. Erosions strips DO come off and can create a lot of shake. I think that that might mean a trip to Germany. Just know what you are getting into before you buy it. Also the props they sell are NOT certified or checked with modified engines. If the dealer says that it has been tested, ask them to show you the STC paper work where that prop was tested, on what engine, airframe and if the engine had modifications (EI, high Comp pistons). The nice thing about hartzell they tested their props on modified engines on RV's. Has MT tested electronic ignition, FADEC,Hi-comp etc... I doubt it. However the fact MT's are made of wood I doubt it has a harmonic fatigue life issue. On the other hand would you feel better with a 20 year old aluminum prop or a 20 year old wood/composite/bonded prop. Chances are both would be fine, but a Hartzell with out corrosion or visable cracks on the surface is eaisier to check.
MT makes a nice product but it is not the state of the art composite construction. No one in aerospace uses wood cores anymore. The down side with the other composite props (WW and AC) is they are stiffer and will not be as smooth. They also still cost a lot and repair shops are few and far between. Infact you may have to send it to the factory for repair, just like a MT would but at least they are in the states. Also you are talking about an experimental prop. The MT is smooth because of the wood core more than the number of blades. May be a suggestion would be go with a 2 blade MT composite/wood prop.
George