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#41
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On Thu, 01 Jan 2004 16:25:57 GMT, "Mike Rapoport"
wrote: If it had more compressor capacity then we would want a larger turbine for more power. The real question is how high do you want to go in an unpreasurized airplane? Now you're confusing me. I don't expect any turboprop airplane to run out of poop in the low teens. Max rated thermo hp isn't the issue, it's running out of it before getting to an altitude where acceptable gains in true airspeed are made. The real question is how much power is available and the specific fuel consumption in let's say between 9,000-15,000 msl. Again, unless they've made some big changes in the powerplant, you don't need to worry about getting too "high" unpressurised. TC You're a turbine guy, you should be familiar with the effects/affects of altitude with respect to turbine temp and available power produced at altitude. Unless things have changed one heckuva lot since I researched one for a customer, the turbine A36 needs one heckuva lot more compressor. TC |
#42
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A few hundred pounds empty?
Mike MU-2 "Ron Natalie" wrote in message m... "Mike Rapoport" wrote in message hlink.net... I am at a loss as to why the weight of the subject airplane is so high. The turbine engine itself weighs less. Not having the article, I have to assume that the plane has a lot of avionics and a heavy interior. You start adding radar, SS, lots of radios, cabin entertainment and other gizmos and soon the plane has gained 300lbs. Range is usually the shortcoming of piston to turbine conversions but the Allison engine in the 210 works out well from a range standpoint, so I don't see why the Bonanza wouldn't as well. Is the article availible online? The tips add a few hundred bounds. The D'shannon tips are about 100lbs and these things look bigger. |
#43
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I didn't design the conversion or even talk to the guy who did but consider
that there are a number or constraints: 1) Vmo (which will be the same as Vno in the piston Bonanza) 2) Mmo, does anyone even know what the maximium permissable mach number is for a Bonanza? Probably even Beech does not. 3) Weight and balance, you can't put a huge engine out in front. 4) Fuel burn at expected altitudes (high teens) a bigger compressor takes a lot of power to turn at low altitudes. At sea level my TPE 331s each burn 36gph idling (the props are at flat pitch.. I think (guess) that they were looking for somewhat better performance than a turbocharged piston Bonanza across the existiong flight envelope, but not to extend that envelope too far in either speed or altitude. If they put an engine into the airplane that would make 300hp at FL310, they would probably have to completely re-flight-test the airplane. I am a little confused by your post as well. An engine can only make its thermodynamic horsepower at sea level and ISA, so you are below that at any flight altitude. Mike MU-2 wrote in message ... On Thu, 01 Jan 2004 16:25:57 GMT, "Mike Rapoport" wrote: If it had more compressor capacity then we would want a larger turbine for more power. The real question is how high do you want to go in an unpreasurized airplane? Now you're confusing me. I don't expect any turboprop airplane to run out of poop in the low teens. Max rated thermo hp isn't the issue, it's running out of it before getting to an altitude where acceptable gains in true airspeed are made. The real question is how much power is available and the specific fuel consumption in let's say between 9,000-15,000 msl. Again, unless they've made some big changes in the powerplant, you don't need to worry about getting too "high" unpressurised. TC You're a turbine guy, you should be familiar with the effects/affects of altitude with respect to turbine temp and available power produced at altitude. Unless things have changed one heckuva lot since I researched one for a customer, the turbine A36 needs one heckuva lot more compressor. TC |
#44
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"Mike Rapoport" wrote in message hlink.net... A few hundred pounds empty? The Osborn tanks I believe weight about an 100 for the pair I thought. I may be wrong. Maybe it was 50 for the pair. I'll have to dig. I know that the gross weight increase on the Navion for them is exactly the weight of the fuel in the tanks plus the weight of the STC kit. |
#45
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On Fri, 02 Jan 2004 05:37:58 GMT, "Mike Rapoport"
wrote: I think (guess) that they were looking for somewhat better performance than a turbocharged piston Bonanza across the existiong flight envelope, but not to extend that envelope too far in either speed or altitude. If they put an engine into the airplane that would make 300hp at FL310, they would probably have to completely re-flight-test the airplane. You seem to have hit the nail on the head, intentionally or accidentally. A turbo-normalized or turbo-supercharged engine in an A-36 should have no issues with delivering 75% of rated TO hp well into the teens. Again, it has admittedly been several years since I did the research for a prospective customer (for whom $$ was by no means an issue), but the power "curve" of the 250 was less than desirable when compared to a turbo piston-pounder. Specific fuel consumption was approximately 1/3 higher, with the additional fuel storage neccessary to retain "acceptable" range capabilities. There are many existing aircraft types that have been "re-engined" with powerplants drastically exceeding the original installations. In a lot of cases, no "flight-test"-ing is required, nor is it needed. Engine operating limitations are changed so as not to exceed the original levels. I would certainly agree that testing would need to be performed if increasing the usable hp-thrust rating. I am a little confused by your post as well. An engine can only make its thermodynamic horsepower at sea level and ISA, so you are below that at any flight altitude. I apologize if I wasn't clear, or it may be a case of miscommunication. It's likely when looking at "newer" t-prop aircraft you will notice that the gas generator is likely capable of exceeding airframe limitations at max thermo-hp. Hence, at altitude it has no problems producing a very high percentage of "max take-off" power. I'm sure you know this. They are few and far between, but there are A-36's flying around with 350 hp turbo-supercharged Lycoming engines. Aside from the differences in initial rate of climb, I would be willing to bet the the overall performance numbers would be more than comparable to the turbine conversion. The guy I spoke to that had one could only lament the fact that he had to burn 22-25 gph in cruise... Regards; TC snip |
#46
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I fly a Cessna P210 with a turbine conversion. Used to fly a turbo Arrow.
I'm based in the south and I have found engine heat at altitude to be the limiting factor for both the turbine and piston. On cold days, you can go a good 20-30 knots faster than hot days at altitude with the turbine. On hot days with my Arrow at altitude, I always seemed to be worried about cylinder head temps. The Allison engine is much lighter than the piston, but you have to carry more fuel, so it's a wash. Plus Jet-A is 10 percent heavier than Avgas. However, the lighter turbine engine allows for tip and aft auxiliary tanks which extend my range to 1200 nautical miles. Fuel burn is 25 gallons--quite a bit more than the piston, offset slightly by the lower cost of Jet-A. Nevertheless, I have found increased speed, although nice, not nearly as important as the comfort of knowing a turbine has substantially higher reliability than a piston. Next is the quiet and smoothness of the plane, it's climb ability, huge feathered-prop glide ratio and, being pressurized, the ability to get quickly on top of the bumpy cumulo level in the summer. wrote in message ... On Fri, 02 Jan 2004 05:37:58 GMT, "Mike Rapoport" wrote: I think (guess) that they were looking for somewhat better performance than a turbocharged piston Bonanza across the existiong flight envelope, but not to extend that envelope too far in either speed or altitude. If they put an engine into the airplane that would make 300hp at FL310, they would probably have to completely re-flight-test the airplane. You seem to have hit the nail on the head, intentionally or accidentally. A turbo-normalized or turbo-supercharged engine in an A-36 should have no issues with delivering 75% of rated TO hp well into the teens. Again, it has admittedly been several years since I did the research for a prospective customer (for whom $$ was by no means an issue), but the power "curve" of the 250 was less than desirable when compared to a turbo piston-pounder. Specific fuel consumption was approximately 1/3 higher, with the additional fuel storage neccessary to retain "acceptable" range capabilities. There are many existing aircraft types that have been "re-engined" with powerplants drastically exceeding the original installations. In a lot of cases, no "flight-test"-ing is required, nor is it needed. Engine operating limitations are changed so as not to exceed the original levels. I would certainly agree that testing would need to be performed if increasing the usable hp-thrust rating. I am a little confused by your post as well. An engine can only make its thermodynamic horsepower at sea level and ISA, so you are below that at any flight altitude. I apologize if I wasn't clear, or it may be a case of miscommunication. It's likely when looking at "newer" t-prop aircraft you will notice that the gas generator is likely capable of exceeding airframe limitations at max thermo-hp. Hence, at altitude it has no problems producing a very high percentage of "max take-off" power. I'm sure you know this. They are few and far between, but there are A-36's flying around with 350 hp turbo-supercharged Lycoming engines. Aside from the differences in initial rate of climb, I would be willing to bet the the overall performance numbers would be more than comparable to the turbine conversion. The guy I spoke to that had one could only lament the fact that he had to burn 22-25 gph in cruise... Regards; TC snip |
#47
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"Wyatt Emmerich" wrote: I fly a Cessna P210 with a turbine conversion. What are your max gross, useful load and usable fuel capacity? -- Dan C172RG at BFM (remove pants to reply by email) |
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