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#1
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MT Props w/Electric Pitch Control
Anyone care to comment on using one of MT's composite blade props with
electric pitch control? Eggenfellner seems to really want you to use this prop with his Subaru setup. I'm a bit concerned both with a composite prop and an electric pitch control. |
#2
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On Wed, 31 Mar 2004 19:51:59 GMT, "x" wrote:
Anyone care to comment on using one of MT's composite blade props with electric pitch control? Eggenfellner seems to really want you to use this prop with his Subaru setup. I'm a bit concerned both with a composite prop and an electric pitch control. I don't think there's anything wrong with a properly made composite prop, and MT is one of better known prop manufacturers. They make LOTS of props, many of them for certified airplanes. What's your specific concern? Corky Scott |
#3
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On Wed, 31 Mar 2004 19:51:59 GMT, "x" wrote:
Anyone care to comment on using one of MT's composite blade props with electric pitch control? Eggenfellner seems to really want you to use this prop with his Subaru setup. I'm a bit concerned both with a composite prop and an electric pitch control. ++++++++++++++++++++++++++++++++++ snort You worry about the wrong end of the propulsion system. Get your priorities straight. Be far, far more concerned with the Soob application.. Signed, N.E. Juan |
#4
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"Corky Scott" wrote in message
... On Wed, 31 Mar 2004 19:51:59 GMT, "x" wrote: Anyone care to comment on using one of MT's composite blade props with electric pitch control? Eggenfellner seems to really want you to use this prop with his Subaru setup. I'm a bit concerned both with a composite prop and an electric pitch control. I don't think there's anything wrong with a properly made composite prop, and MT is one of better known prop manufacturers. They make LOTS of props, many of them for certified airplanes. What's your specific concern? Corky Scott I don't know anything about using composite construction for a propeller. I do know a little about fiberglass and carbon fiber composite, just from an "educated layman" point of view. So bearing that in mind, I would be worried about: 1) Would continual flex/unflex cause fatigue and how would you detect it if it's internal? (I think in the research environment they basically CAT scan parts to look for internal fatigue?) 2) How could you tell a trivial rock ding from a potentially disastrous one (again, hard to see what's inside)? Again, I'm not all all claiming these things happen, I just am asking if people know of any gotchas. Of course, there are lots of testimonials that basically say "I've had mine for X years and it hasn't broken yet", but that's not really data. Secondly, does the electric system work automatically (so that you don't do anything), or is there a control that works like manifold pressure (i.e. "governed" so that changes in RPM cause automatic changes in blade pitch), or is there just a blade pitch control? Why would it be better/worse than hydraulic? Does anyone out there have one who can ring in on this? |
#5
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I can tell you that they make composite props for military applications that
include dirt strip transport planes ( I think some C130's are using MT's ). A composite prop is not like a composite wing. What you see is what you get. There is no wondering what stresses are going on inside anymore than there is with a metal prop. Most dings can be fixed by filling up and building up with epoxy, then sanding. If the ding meets a certain size, then it has to be inspected by MT or someone specially trained. Advantages of composite props are reduced weight and noise along with a shock absorbing kind of flex. Disadvantages are that little dings that would only scratch a metal prop will require epoxy repairs (but they are easy and cheap repairs. Given that most homebuilts will never fly enough hours to make a difference in the maintenance costs, the MT is not a bad idea at all. Mine is smooth and quiet, and I like it. "x" wrote in message news:TcIac.45575$gA5.568680@attbi_s03... "Corky Scott" wrote in message ... On Wed, 31 Mar 2004 19:51:59 GMT, "x" wrote: Anyone care to comment on using one of MT's composite blade props with electric pitch control? Eggenfellner seems to really want you to use this prop with his Subaru setup. I'm a bit concerned both with a composite prop and an electric pitch control. I don't think there's anything wrong with a properly made composite prop, and MT is one of better known prop manufacturers. They make LOTS of props, many of them for certified airplanes. What's your specific concern? Corky Scott I don't know anything about using composite construction for a propeller. I do know a little about fiberglass and carbon fiber composite, just from an "educated layman" point of view. So bearing that in mind, I would be worried about: 1) Would continual flex/unflex cause fatigue and how would you detect it if it's internal? (I think in the research environment they basically CAT scan parts to look for internal fatigue?) 2) How could you tell a trivial rock ding from a potentially disastrous one (again, hard to see what's inside)? Again, I'm not all all claiming these things happen, I just am asking if people know of any gotchas. Of course, there are lots of testimonials that basically say "I've had mine for X years and it hasn't broken yet", but that's not really data. Secondly, does the electric system work automatically (so that you don't do anything), or is there a control that works like manifold pressure (i.e. "governed" so that changes in RPM cause automatic changes in blade pitch), or is there just a blade pitch control? Why would it be better/worse than hydraulic? Does anyone out there have one who can ring in on this? |
#6
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We are an MT dealer and have sold quite a few of the electric controlled units
along with a bunch of hydraulic standard and aerobatic as well as a few fully reversable units. The props are by far first rate pieces with more engineering behind them than most auto conversions or kit airframe designs. We have worked with MT to obtain STC's for props on certified airplanes and I was amazed at the huge amount of data they gather for every prop they build. The build the props we recommned for our kit aircraft as well as have built special one of a kind props for us. The blades are wood core with a special high strength compressed wood at the root. The blades are epoxy glass covered and have stainless steel leading edges bonded to them for errosion protection. The blades are extremely duarble and approved for flight in rain. The wooden core have near limitless fatique cycle. The electric control unit is a panel mounted device with a display and knob used to set the desired RPM much like the Beech electric prop we had on our old bonanza. IT works as any constant speed prop to hold the RPM at the pilot selected point. Feel free to email me directly if I can answer any other questions for you. Kevin Kimball |
#7
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On Wed, 31 Mar 2004 23:09:43 GMT, "x" wrote:
"Corky Scott" wrote in message ... On Wed, 31 Mar 2004 19:51:59 GMT, "x" wrote: Anyone care to comment on using one of MT's composite blade props with electric pitch control? Eggenfellner seems to really want you to use this prop with his Subaru setup. I'm a bit concerned both with a composite prop and an electric pitch control. I don't think there's anything wrong with a properly made composite prop, and MT is one of better known prop manufacturers. They make LOTS of props, many of them for certified airplanes. What's your specific concern? Corky Scott I don't know anything about using composite construction for a propeller. I do know a little about fiberglass and carbon fiber composite, just from an "educated layman" point of view. So bearing that in mind, I would be worried about: 1) Would continual flex/unflex cause fatigue and how would you detect it if it's internal? (I think in the research environment they basically CAT scan parts to look for internal fatigue?) 2) How could you tell a trivial rock ding from a potentially disastrous one (again, hard to see what's inside)? Again, I'm not all all claiming these things happen, I just am asking if people know of any gotchas. Of course, there are lots of testimonials that basically say "I've had mine for X years and it hasn't broken yet", but that's not really data. There are a number of businesses making composite props in the world today, some of them making props for extreme aviation endeavors. MT and Hoffman make composite props that are used in unlimited aerobatic competitiions. In the world of props, metal props are the most dangerous in that they can and do vibrate in sympathy with the engine harmonics and can rapidly fatigue and fail. Some conditions are so dangerous that the airplane/engine/prop combination has a plackard requiring that the pilot avoid operations at a specific rpm. Wooden props are at the other end of the spectrum, they actually deaden vibrations. Composite props are somewhere in between those two extremes. MT and Hoffman are big time players in the world of certified and experimental props, and their prices reflect that. Secondly, does the electric system work automatically (so that you don't do anything), or is there a control that works like manifold pressure (i.e. "governed" so that changes in RPM cause automatic changes in blade pitch), or is there just a blade pitch control? Why would it be better/worse than hydraulic? Does anyone out there have one who can ring in on this? Electrically controlled props may or may not also be governed. Some just adjust pitch, others adjust pitch and govern rpm. If you have an electric adjustable prop in mind, the best thing to do would be to ask the vendor what it's designed to do. Corky Scott |
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