MB65E Posted October 14 Report Posted October 14 That RR Maule is awesome! Flew one in PHX for a time. Just recently did a light overhaul on PT6, for some light corrosion and calendar time. It was north of $560k for the work at PWC. -Matt 1 Quote
Shadrach Posted October 14 Report Posted October 14 On 10/12/2024 at 2:14 PM, A64Pilot said: Maule built a Turbine, with the little Allison, sold I think 6, it was of course the cheapest Turbine you could buy, although it climbed like a raped ape, it’s Stol performance wasn’t as good as the Piston Maules. http://www.pilotfriend.com/aircraft performance/Maule/28.htm The little Allison was developed by Detroit Diesel in 1958 specifically to be either in a small scout helicopter or a small observation airplane, it was used in the OH-6 and the OH-58, so no, no consideration for high altitude. https://en.wikipedia.org/wiki/Allison_Model_250 I was an OH-58 Crew Chief for three years before flight school, the baby Allison came in two flavors, 318 SHP and 420 SHP. For a small turbine to work efficiently you have to have extremely tight clearances on the compressor, the little Detroit Diesel / Allison gets that by its compressor halves are plastic lined on assembly the compressor blades contact this lining and you spin the compressor and it shaves itself in. Starting one is sort of an emergency procedure, east to screw up as it WILL get hot and be in a time limited temp range that from 40 years ago was a six second limit. You really had to give it full attention By contrast you have to be truly stupid to hot start a Pratt, about the only way you can is with a nearly dead battery and even then it gives you plenty of time to abort the start. I guess another way is to truly flood the motor and then hit the igniters. That seems like a very useful air frame/power plant combination. Too expensive to certify it a higher useful load? It obviously had enough wing and certainly enough power. 900lbs is pretty piss poor considering it’s actual capabilities. Quote
dkkim73 Posted October 14 Report Posted October 14 Saw a really nice looking Silver Eagle (turbine P210) at the home FBO yesterday. Apparently the guy comes here regularly so I'll have to ask him about it. Looked very useful, FIKI, spacious, pressurized. Pretty spendy on Controller, though competitive with the options. TY all for the education about turbine maintenance. 1 Quote
exM20K Posted October 14 Report Posted October 14 59 minutes ago, dkkim73 said: Saw a really nice looking Silver Eagle (turbine P210) at the home FBO yesterday. Apparently the guy comes here regularly so I'll have to ask him about it. Looked very useful, FIKI, spacious, pressurized. Pretty spendy on Controller, though competitive with the options. TY all for the education about turbine maintenance. Meh. Old, unsupported airframe. I'd be really surprised if O&N was able to retain the FIKI cert with the engine swap. From the 210 Expert Paul New Last but not least are the two outflow valves mounted on the aft pressure bulkhead. They are basically the same, except one is controlled with an electric solenoid and the other with pneumatics from the altitude controller. These valves have been out of production and support for a very long time. At least one company in Florida attempts to keep the community supplied with working units. The lack of new parts means they are limited to repairs, no overhauls, and mostly with serviceable parts. These two components are the ones that concern me the most when considering the continuing viability of the pressurization system on the P210. He did write this six years ago, and I don't know if a new solution exists. Silver Eagle << Jetprop at similar pricing. Your Acclaim is faster and has longer legs. From AOPA: The O&N pilot’s manual appears as a Flight Manual Supplement to the Cessna P210N Pilot’s Operating Handbook, and does not provide performance charts other than landing and takeoff data. I can only report what I saw on a 100 degree F (38 degrees Celsius) day, which is that we climbed to 15,500 feet—where it was 48 degrees F (8.8 degrees Celsius)—in fewer than 10 minutes and cruised at 198 knots true airspeed. Occasionally I saw 200 KTAS. O&N officials promise 215 KTAS at 16,000 feet in cooler temperatures. Turbine engines are temperature sensitive. I could be talked into a Jetprop, and we were *this* close after visiting with @Jerry 5TJ to see his some years back. -dan Quote
dkkim73 Posted October 14 Report Posted October 14 2 hours ago, exM20K said: Silver Eagle << Jetprop at similar pricing. Your Acclaim is faster and has longer legs. Good points. Definitely not disatisfied with the Acclaim. I was just thinking about pressurization and some of the reliability factors of a turboprop. I was also wondering if I had been missing something in terms of speed in the specs, but apparently not! Interestingly I am flying ROP for cylinder break in the last 12 hrs or so. Definitely seeing some significantly higher speeds without even trying. Really great to have the flexibility. D Quote
aviatoreb Posted October 14 Report Posted October 14 Mooney aircraft - the factory - had made some moves to hang a Turbine on the front end of the M20. There was a planned RR500 - a little smaller than whats in the helicopter engine on the Bonanza turbine. So maybe a little better fuel specifics? I dont know but I dont think Rolls Royce ended up making that engine in the end and Mooney took one of its typical bankruptcy moves... https://www.flightglobal.com/mooney-chooses-rr500-turboprop-for-new-product-development/82197.article and it was covered in Mooney space back in 2008 Would have been a fun option. 1 Quote
Pinecone Posted October 15 Report Posted October 15 It looks like the RR300 would be a better fit. 201 pounds, 300 HP. Currently in production as it is the engine in the Robinson R66 helicopter. https://en.wikipedia.org/wiki/Rolls-Royce_RR300 1 Quote
Jerry 5TJ Posted October 15 Report Posted October 15 14 hours ago, exM20K said: I'd be really surprised if O&N was able to retain the FIKI cert with the engine swap. From the 210 Expert None of the P210 Silver Eagle retained the FIKI certification even if the original airframe had been so equipped. 1 Quote
A64Pilot Posted October 15 Report Posted October 15 (edited) On 10/14/2024 at 9:43 AM, Shadrach said: That seems like a very useful air frame/power plant combination. Too expensive to certify it a higher useful load? It obviously had enough wing and certainly enough power. 900lbs is pretty piss poor considering it’s actual capabilities. Limit is structure, I believe it carry’s more fuel than a recip and of course fuel is weight so it comes off of the top. In all honestly for what most consider the most important the 540 Maule outperformed it, shorter takeoff due to weight, shorter landing for the same reason and higher useful load, the turbine outclimbed you of course due to more HP. My M-6/235 at gross weight had a 150-200 ft takeoff roll depending on source but if real light it was honestly closer to 50’. https://planephd.com/wizard/details/432/MAULE-M-6-specifications-performance-operating-cost-valuation?annual_hrs=100&selected_yearmfr=1981 I have no idea how big the numbers are on a runway, but if light I could get off prior to the end of the numbers and could stop before coming off of them usually. And at 9,000 to 11,000 ft with the flaps reflexed it would cruise at 2200 RPM full throttle 50 ROP at 130-135 true, which ain’t bad. as it was only 235 HP it’s max RPM was only 2400, that was how Lycoming turned the power down, the 260 HP 540 was the same motor with higher RPM limits There was even a Turbo Maule that at altitude woukd haul A** for a STOL airplane and performed very close to the 540 at sea level, it was an unusual engine https://planephd.com/wizard/details/581/MAULE-M-5-210TC-specifications-performance-operating-cost-valuation Edited October 15 by A64Pilot 1 Quote
T. Peterson Posted October 15 Report Posted October 15 11 hours ago, Pinecone said: It looks like the RR300 would be a better fit. 201 pounds, 300 HP. Currently in production as it is the engine in the Robinson R66 helicopter. https://en.wikipedia.org/wiki/Rolls-Royce_RR300 I sure hope you and the other knowledgeable fellas will chime in on this particular engine. I have very much enjoyed this thread and often thought it would be cool to have a turbine powered Mooney, but not at the expense of fuel efficiency. Apparently, according to the previous posts, a turbine is very fuel inefficient and even suffers in some situations worse performance. I did not know this, but I wonder if the problem is turbines in general, or the application of a particular engine? In other words could the “right” turbine engine be superior in both performance and efficiency to our current piston engines? For instance this RR300 you described? Of course I realize cost is most likely outrageous, but I am just curious about the suitability of the engine itself. Is a turbine engine simply not suitable to a non pressurized General Aviation aircraft? Quote
A64Pilot Posted October 15 Report Posted October 15 Small turbines often don’t work well the bigger they get the more efficient they become. An exception is a helicopter where weight is vitally important, turbines made helicopters much more useful, you can sacrifice fuel burn for the extra useful load you can get with a helicopter. The OH-58 that I worked on 40 years ago came in two flavors. One had the Allison T63-A700 at 317 SHP the other the Allison T63-A720 at 420 SHP, both carried 71.5 gls of fuel which was good usually for 2.5 hours of normal flying, hovering of course used it faster. So 30 GPH or so? Where turbines shine is high altitude because their compressor can be thought of as a very powerful multi stage turbo, and they are often derated, for example the Compressor is ultimately what determines the max power that can be made because it supplies the cooling air, of course the gearbox has to be able to handle the power too. So we take the engine in the TBM’s, it essentially has the same or similar compressor as the 1700 SHP -67F, but it’s derated to I guess most common is 800 ish SHP? being derated they can save weight by putting a gearbox in it that can only handle 800 ish SHP but with that big compressor it can carry seal level power quite high, how high I have no idea. I am pretty sure the same compressor is used in the PC-12 motor but with a 1200 SHP gearbox. At high altitudes the 800, 1200 and 1700 engine will make similar power The other thing that turbines come into their own is very high HP, you just can’t build a recip that could power a Commercial airliner for instance. At very high altitudes they can be fuel efficient because they can get so high that airframe drag is very low and the aircraft can be very fast, very much like a turbo recip but on steroids. Helicopters it’s all about weight, we can live with high fuel burn for an engine that makes twice the power for half the weight or more. For instance the T-800 designed for the Army made over 1500 SHP and weighed a little over 300 lbs, that’s roughly what our IO-360’s weigh, and it supposedly had a lot more power to come in development. https://en.wikipedia.org/wiki/LHTEC_T800. Very fuel efficient too, but God did it cost $$$. But really what usually kills single engine turbine GA airplanes is the $$$, I don’t know what they cost but I bet the TBM’s cost a pretty penny, and the operating cost you could likely operate a fleet of J models. 1 Quote
carusoam Posted October 15 Report Posted October 15 Unfortunately… unpressurized and turbine don’t go together very often… 1) Always on O2 2) altitude limited 3) fuel economy 4) too low, fuel burn is high, while airspeed is limited… 5) too high, time of useful consciousness is limiting… one missed problem with O2 delivery can lead to sleeping while flying… there are a few MSers flying the Piper P46T and it’s derivatives… And at least one Lancair IVPT for fun, look at the Lancair Evolution… pressurized, turbine, and Experimental… one interesting thing turbines may have… putting the prop into beta… to reduce stopping distance… I like my Mooney! Going Acclaim would make it slightly better… I have been following the turbine discussion forever… Best regards, -a- 1 Quote
A64Pilot Posted October 16 Report Posted October 16 32 minutes ago, T. Peterson said: I sure hope you and the other knowledgeable fellas will chime in on this particular engine. I have very much enjoyed this thread and often thought it would be cool to have a turbine powered Mooney, but not at the expense of fuel efficiency. Apparently, according to the previous posts, a turbine is very fuel inefficient and even suffers in some situations worse performance. I did not know this, but I wonder if the problem is turbines in general, or the application of a particular engine? In other words could the “right” turbine engine be superior in both performance and efficiency to our current piston engines? For instance this RR300 you described? Of course I realize cost is most likely outrageous, but I am just curious about the suitability of the engine itself. Is a turbine engine simply not suitable to a non pressurized General Aviation aircraft? That engine from the article is essentially the same as the early models of T63’s that I worked on, I suspect the emphasis is on cost, but it’s going to have a high fuel burn. If you could get a turbine cheap enough then they would make sense for GA aircraft. They work for Ag aircraft because for instance with the Thrush H-80 its empty weight was just under 5,000 lbs, but its Certified gross weight is 10,500 lbs. It would be real tough to build a recip that could come close, the 600 HP R-1340 Thrush on a very similar airframe was a 6,000 lb gross weight airplane for instance, so on paper that extra turbine $$$ buys you 4,500 lbs more useful load, actually closer to 4,000 because there is a lot more structure in an H-80, but still two more tons of chemical can spray a lot more acreage. Then add in the turbine is at least 40 MPH faster. 1 Quote
dkkim73 Posted October 16 Report Posted October 16 I spoke with many people looking for an airplane last year. At least one Mooney broker told me that the Acclaim was "turboprop #s on a piston budget". This seems truer than not. It seems like @A64Pilot has forgot more about turbines than many of us know... 1 Quote
T. Peterson Posted October 16 Report Posted October 16 You fellas have certainly come to the table with a plethora of information and I am very grateful for your insights! Quote
carusoam Posted October 16 Report Posted October 16 One of the odd costs to keep in mind while doing the math… the OH cost of the turbine is about 2X of an OH of a Mooney engine… but… hours to TBO is about 2X of the recip… roughly speaking… -a- 2 Quote
Schllc Posted October 16 Report Posted October 16 It’s less to do with physics and more to do with demand. When Ted smith designed the Aerostar, it was clean sheet from the start for turbofan engines. The rate of development, and the demand for general aviation had never been higher. He assumed that development of small jet engines would come very rapidly. In fact I bet all of the major engine manufacturers explored it at least in design if not prototype. The demand never materialized, there was no ga market at all for small jet engines, or turboprops. The upfront design, cost to manufacture and develop to a point it was efficient, is impractical at our numbers. Even if every single piston in the US wanted to convert to turboprop, it would still be a relatively small market. Prices may drop by half, but even then they would still be prohibitively expense for most of us. The only reason we would ever see a turbine on a Mooney is for the cool factor, by someone that has the time, money and will to make it happen. And it would be cool as hell to see. Quote
Schllc Posted October 16 Report Posted October 16 55 minutes ago, carusoam said: One of the odd costs to keep in mind while doing the math… the OH cost of the turbine is about 2X of an OH of a Mooney engine… but… hours to TBO is about 2X of the recip… roughly speaking… -a- I don’t think you can get a turbine overhauled for 200k. Definitely not a pt6. Closer to 600k 2 1 Quote
dkkim73 Posted October 16 Report Posted October 16 47 minutes ago, Schllc said: I don’t think you can get a turbine overhauled for 200k. Definitely not a pt6. Closer to 600k You just burned down my village... 5 Quote
Pinecone Posted October 16 Report Posted October 16 13 hours ago, A64Pilot said: mmercial airliner for instance. At very high altitudes they can be fuel efficient because they can get so high that airframe drag is very low and the aircraft can be very fast, very much like a turbo recip but on steroids. https://en.wikipedia.org/wiki/Lycoming_XR-7755 Quote
Pinecone Posted October 16 Report Posted October 16 11 hours ago, Schllc said: I don’t think you can get a turbine overhauled for 200k. Definitely not a pt6. Closer to 600k But they have much longer times between overhaul. Their hot section inspection interval is similar to our overhaul period. 1,500 to 2,000 hours, with overhauls at twice that interval. And most are run on condition, inspected and if all it well, keep running it. And also, there are programs to pay over time for your overhaul, which is a fixed price. "Pratt & Whitney's P&WC Smart Maintenance Solutions program offers flat-rate overhaul pricing for many PT6A models. This program can help operators predict and contain variable costs. For example, the P&WC Smart Flat Rate Overhaul Program for the PT6A-21 engine has a capped price for optional parts replacement. " Quote
Pinecone Posted October 16 Report Posted October 16 The other issue that was touched on, comes when converting a piston airframe to turbine and the is Vne. In short, the start of the yellow arc (max structural cruising speed) becomes redline. So this also limits performance. Quote
Schllc Posted October 16 Report Posted October 16 11 hours ago, Pinecone said: But they have much longer times between overhaul. Their hot section inspection interval is similar to our overhaul period. 1,500 to 2,000 hours, with overhauls at twice that interval. And most are run on condition, inspected and if all it well, keep running it. And also, there are programs to pay over time for your overhaul, which is a fixed price. "Pratt & Whitney's P&WC Smart Maintenance Solutions program offers flat-rate overhaul pricing for many PT6A models. This program can help operators predict and contain variable costs. For example, the P&WC Smart Flat Rate Overhaul Program for the PT6A-21 engine has a capped price for optional parts replacement. " They absolutely do have longer tbo, some of the honeywell engines in the commanders go 10,000 hours. The challenge is on the rolls royce that is in the bonanza, a hot section can be 25k, or it can be 150k. its based on condition, and one hot start can do a LOT of damage. A buddy of mine had a prop strike in his Meridian, hit a snow bank. The repair was $590k and took 9 months. Turbines are not just more money, they are an order of magnitude more money. The challenge is that they are extremely sophisticated, and relatively rare, so that equals $$$. But if I had the money to figure out a way to put one on a Mooney I would do it! Seems like an m22 would be the ideal candidate. 1 Quote
aviatoreb Posted October 16 Report Posted October 16 5 minutes ago, Schllc said: They absolutely do have longer tbo, some of the honeywell engines in the commanders go 10,000 hours. The challenge is on the rolls royce that is in the bonanza, a hot section can be 25k, or it can be 150k. its based on condition, and one hot start can do a LOT of damage. A buddy of mine had a prop strike in his Meridian, hit a snow bank. The repair was $590k and took 9 months. Turbines are not just more money, they are an order of magnitude more money. The challenge is that they are extremely sophisticated, and relatively rare, so it that equal $$$. But if I had the money to figure out a way to put one on a Mooney I would do it! Seems like an m22 would be the ideal candidate. Why is it that turbine engines are so much very much more expensive? At first blush they seem like a simpler concept. I know the thing that has to do with creating single crystal material is intensely complex but is that technology in a standard PT6 or a RR300? I just dont understand why a turbine engine is 5 or 10 times as expensive as a piston aviation engine which is already 10 times as expensive as the equivalent car engine (that last I get because of economy of scale - and the car engine has better precision in build). Well I would love to have an RR500 (that mythical engine that Mooney never got built) hanging on the end of my nose - but in reality if I had the money to think about that I wouldnt likely do it - the turbine Mooney already exists - I would more likely buy a used TBM700. And after all it is a Mooney - M in TBM is for Mooney. It's a more modern Mooney 301 - which was an early 1980 Mooney concept plane that eventually morphed and lead directly to the TBM700. 1 Quote
Schllc Posted October 16 Report Posted October 16 6 minutes ago, aviatoreb said: Why is it that turbine engines are so much very much more expensive? I am not sure, but I suspect it has a lot to do with the quantity that they made and are servicing. if there were 2 million of them in service it would probably be a lot cheaper. But they throw in the "its for aviation" factor and all bets are off. Quote
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