Was the Nomad really that bad?
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I'm with tinpis. Always considered it supplemented a Twotter on thin routes like an Islander does, but the real gem for the regular stuff would always be the 'solid as a brick s...house' 300 Twotter. A stretched or pumped up (3 abreast ?) Islander with the Allisons would have put paid to it as a companion at the time though. 'Course with a 2 pilot rule, the economics of an aircraft with so few revenue seats becomes moot.
Last edited by frigatebird; 25th Dec 2009 at 09:56.
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21st Century Nomad
Ok , so if the Nomad was going to go back into production what engines and other mods would you choose and what would you call it ?
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The original design was for a single PT6. It would have been the C208 caravan! but then the military came up with impossible requirements for STOL and of course 2 engines. The double slotted flaps were designed to go to 60 degs but after flight testing had to be limited to 38 deg. The front flap slot does nothing at 38, so can be done away with. A T tail was designed and promised 15 kts more with reduced Vmc. Would be nice. The engine cowls design were crap and the oil cooling totally inadequate. Needs redesign. The B17 allisons eventually worked once the gear box was sorted but the rejection rate from the manufacturer was reported to be up around 50%. Maybe they kept the good ones. An LTP101 engine installation was considered but the redesign would not be worth it due sertification costs. The issue of 2 engines vs 1 meant the a/c had to meet a OEI climb requirement which limited its MTOW. With 840 shp its MTOW is below the C208 with 675 shp because the C208 doesn't have to meet the OEI requirement! Go figger!. The chain drive u/c was a bad idea, copied from the early B200? but is a retracting u/c required anyway?. The u/c pod probably caused just as much drag as faired exposed wheels would. The mesh pilot seats? Love them or hate them. I still suffer back problems from 8 hr flight days. The Short fuselage N22? Way too noisy up front, (total pilot door redesign required) and the pilot seat relocation due prop arc was disastrous for comfort. Stick with the N24/A. Oh and produce it outside of Australia!. The local regulator couldn't get past protecting one's ar$e mentality by AD'ing it into extinction and they don't have the expertise anyway. And don't offer it to the aus military.
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With Mahindra & Mahindra buying Gippsland Aero it will probably be reborn as the Hindustan Air Ambassador
But the wings......................are they optional extras on the Air Ambassador TP?
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Looking for Photos Provincial Air Services Nomads
Operating in PNG early 80s.. One was blue, one yellow dont recall the other
Operating in PNG early 80s.. One was blue, one yellow dont recall the other
P2-IAT (construction number N22B-27):
Clyde North Aeronautical Preservation Group - CNAPG.
GAF N.22B Nomad, P2-IAT
P2-IAC (N22B-37):
Clyde North Aeronautical Preservation Group - CNAPG..
P2-IAM (N22B-93):
Clyde North Aeronautical Preservation Group - CNAPG.
Regards,
David
Often wondered why GAF didn't go with a couple of 331s or PT-6s over the converted helicopter engines? Would have been interesting to see how performance stacked up with better speced engines. Would the market have treated the Nomad differently with more reliable, more powerful engines?
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Many Nomad accidents/incidents seem to have been caused by the engines.
If this is the case, why is Gippsland Aeronautics sticking with a similar type of engine for their modernised N24 Nomad? Their website says:
The Gippsland Aeronautics Nomad will feature:
* Reliable Rolls Royce 250-B17F/1 Engines
* Latest technology Hartzell propellers
* Glass cockpit technology
No mention of the fixes for the tailplane issues, the skin being too thin, nor the undercarriage issues.
I'm guessing that fixes such as PT6s replacing the RR250 engines etc would require added certification costs.
Anyone from Gippsland Aeronautics able to answer?
Thanks,
David
If this is the case, why is Gippsland Aeronautics sticking with a similar type of engine for their modernised N24 Nomad? Their website says:
The Gippsland Aeronautics Nomad will feature:
* Reliable Rolls Royce 250-B17F/1 Engines
* Latest technology Hartzell propellers
* Glass cockpit technology
No mention of the fixes for the tailplane issues, the skin being too thin, nor the undercarriage issues.
I'm guessing that fixes such as PT6s replacing the RR250 engines etc would require added certification costs.
Anyone from Gippsland Aeronautics able to answer?
Thanks,
David
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The words were:
QUOTE:It is the only machine that has gone some way to rivaling the Twin Otter! (Read Twin Engine STOL)
I was comparing them from the stol perspective, & design purpose's only, maybe you could enlighten me? TINNIE, as to what else you go some way to fairly compare both the N22 /24 to, for that matter.
The original design was a brilliant concept:
A former GAF pilot employed on testing the machines (Circa 1987-cant remember his name) once told me, the concept IS fraught with finance issues, and the design team wanted to change/ alter the rear end, and fit bigger engines,(his choice was PT6-s') and redesign the main U/C system to support bigger tires.
If this is true or just bar talk I dont know, but the chap was the genuine goods, so I feel it rather solid.
Read the attached:
GAF Nomad
From Wikipedia, the free encyclopedia
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Nomad
N22C Nomad VH-ATO, the only Nomad flying in Australia in 2009
Role STOL aircraft
Manufacturer Government Aircraft Factories
First flight 23 July 1971
Status Still in civil and military service
Primary users Philippine Air ForceAustralian ArmyIndonesian National Navy
Produced 1975 - 1985
Number built 172
The GAF Nomad is a twin-engine turboprop, high-winged, "short take off and landing" (STOL) aircraft . It was designed and built by the Australian Government Aircraft Factories (GAF) at Fishermens Bend, Melbourne. Major users of the design have included the Royal Flying Doctor Service of Australia, the Australian Army and the Australian Customs Service.
Contents[hide]· 1 Design and development· 2 Variants· 3 Operators o 3.1 Civil Operatoro 3.2 Military operators· 4 Notable incidents· 5 Specifications (N22B)· 6 References· 7 External links
[edit] Design and development
Development of the Nomad began in 1965 at the Government Aircraft Factories as Project N. The Australian government funded two prototypes in January 1970 for the twin engined, multi-purpose transport. The government was keen to build an aircraft in order to maintain aircraft production at GAF after the end of Mirage III production.[1] The first prototype (VH-SUP) flew for the first time on 23 July 1971. The aircraft was now known as the N2 and was aimed at the military and civilian markets. The designation N22 was to be used for military aircraft (becoming N22B in production) and N24 was to be used for the lengthened civilian version.
The original design intention was that the entire empennage would be hinged, such that it could be swung open providing rear loading access (the target payload was a small vehicle). This necessitated the raised cruciform tail.
The Nomad design was considered problematic and early Royal Australian Air Force evaluations were critical of the design. An early, stretched-fuselage variant crashed, killing GAF's chief test pilot (the father of actor Guy Pearce),[2] and assistant head designer. The Nomad has been involved in a total of 24 total hull-loss accidents, and 76 fatalities.[3]
Only 172 Nomads (including the two prototypes) were manufactured, due to the limited foreign sales achieved by GAF. In 1986, GAF was incorporated into Aerospace Technologies of Australia.[1][4]
On 18 June 2008, Gippsland Aeronautics announced they had won bidding to take over the Nomad's type certificate and would probably be restarting production.[5] Gippsland Aeronautics is working to return an upgraded version of the N24 to production in 2011.[6]
As of December 2009 only one Nomad is still flying in Australia, with another four in New Zealand.[7][8][9]
Chr's.
H/Snort
I was comparing them from the stol perspective, & design purpose's only, maybe you could enlighten me? TINNIE, as to what else you go some way to fairly compare both the N22 /24 to, for that matter.
The original design was a brilliant concept:
A former GAF pilot employed on testing the machines (Circa 1987-cant remember his name) once told me, the concept IS fraught with finance issues, and the design team wanted to change/ alter the rear end, and fit bigger engines,(his choice was PT6-s') and redesign the main U/C system to support bigger tires.
If this is true or just bar talk I dont know, but the chap was the genuine goods, so I feel it rather solid.
Read the attached:
GAF Nomad
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Nomad
N22C Nomad VH-ATO, the only Nomad flying in Australia in 2009
Role STOL aircraft
Manufacturer Government Aircraft Factories
First flight 23 July 1971
Status Still in civil and military service
Primary users Philippine Air ForceAustralian ArmyIndonesian National Navy
Produced 1975 - 1985
Number built 172
The GAF Nomad is a twin-engine turboprop, high-winged, "short take off and landing" (STOL) aircraft . It was designed and built by the Australian Government Aircraft Factories (GAF) at Fishermens Bend, Melbourne. Major users of the design have included the Royal Flying Doctor Service of Australia, the Australian Army and the Australian Customs Service.
Contents[hide]· 1 Design and development· 2 Variants· 3 Operators o 3.1 Civil Operatoro 3.2 Military operators· 4 Notable incidents· 5 Specifications (N22B)· 6 References· 7 External links
[edit] Design and development
Development of the Nomad began in 1965 at the Government Aircraft Factories as Project N. The Australian government funded two prototypes in January 1970 for the twin engined, multi-purpose transport. The government was keen to build an aircraft in order to maintain aircraft production at GAF after the end of Mirage III production.[1] The first prototype (VH-SUP) flew for the first time on 23 July 1971. The aircraft was now known as the N2 and was aimed at the military and civilian markets. The designation N22 was to be used for military aircraft (becoming N22B in production) and N24 was to be used for the lengthened civilian version.
The original design intention was that the entire empennage would be hinged, such that it could be swung open providing rear loading access (the target payload was a small vehicle). This necessitated the raised cruciform tail.
The Nomad design was considered problematic and early Royal Australian Air Force evaluations were critical of the design. An early, stretched-fuselage variant crashed, killing GAF's chief test pilot (the father of actor Guy Pearce),[2] and assistant head designer. The Nomad has been involved in a total of 24 total hull-loss accidents, and 76 fatalities.[3]
Only 172 Nomads (including the two prototypes) were manufactured, due to the limited foreign sales achieved by GAF. In 1986, GAF was incorporated into Aerospace Technologies of Australia.[1][4]
On 18 June 2008, Gippsland Aeronautics announced they had won bidding to take over the Nomad's type certificate and would probably be restarting production.[5] Gippsland Aeronautics is working to return an upgraded version of the N24 to production in 2011.[6]
As of December 2009 only one Nomad is still flying in Australia, with another four in New Zealand.[7][8][9]
Chr's.
H/Snort
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Rr250 B17
There seems a Holden/Ford style comparison running hear about the -250 B17 engines compared to the PT6? There is no comparison, PT6s are different engines usually built for aeroplanes with higher power requirements. They are more expensive to buy and to run than the smaller (in size) RR250 range.
NB: the Nomad used the B17C rated at 420 HP whereas other similarly engined aircraft use much lower power ratings. If the 250 engine did have a reliability problem in the Nomad, it was more related to trying to take too much out of it than anything else. To my knowledge, there is no reliability issue on the RR250 range of engines other than that made up in the minds of PT6 advocates. The RR250 is the most prolific turbine ever built, and most commonly found on small single engined helicopters, so most aviators using this kind of engine are obviously happy with the reliability or else there wouldn't be so many flying! Suggestions that use as a helicopter engine means they cannot be used on fixed wing aeroplanes says more about the lack of understanding of turbine engines on the part of the opinion holder than it does on any real science.
Redesigning Nomads to use the RR250 B17F version makes more sense than you think, because it will be a relatively simple change where the costs can be more easily amortised, and the performance requirement is well within the design capability of the newer engine. By comparison, changing to the PT6 would require tens of millions of dollars worth of redesign and no-one these days has that kind of money in the Nomad end of the market.
People need to get consistent with their arguments. Investors only invest if they have a fair chance of getting their money back. At the beginning of the Nomad programme, Australia's usual bunch of naysayers were already trying to kill the aircraft development for some other "nationally important" reasons, and that's why the investment wasn't there up front, and we are left with a design compromise. Other than the fact that this is always the case in aviation, or any other manufacture for that matter, the poorly supported local aircraft industry is following the investment capital overseas. Whining about it now won't help, and PT6 protagonists can bleat all they like about their beloved engine, but maybe they just need to get out a bit more?
NB: the Nomad used the B17C rated at 420 HP whereas other similarly engined aircraft use much lower power ratings. If the 250 engine did have a reliability problem in the Nomad, it was more related to trying to take too much out of it than anything else. To my knowledge, there is no reliability issue on the RR250 range of engines other than that made up in the minds of PT6 advocates. The RR250 is the most prolific turbine ever built, and most commonly found on small single engined helicopters, so most aviators using this kind of engine are obviously happy with the reliability or else there wouldn't be so many flying! Suggestions that use as a helicopter engine means they cannot be used on fixed wing aeroplanes says more about the lack of understanding of turbine engines on the part of the opinion holder than it does on any real science.
Redesigning Nomads to use the RR250 B17F version makes more sense than you think, because it will be a relatively simple change where the costs can be more easily amortised, and the performance requirement is well within the design capability of the newer engine. By comparison, changing to the PT6 would require tens of millions of dollars worth of redesign and no-one these days has that kind of money in the Nomad end of the market.
People need to get consistent with their arguments. Investors only invest if they have a fair chance of getting their money back. At the beginning of the Nomad programme, Australia's usual bunch of naysayers were already trying to kill the aircraft development for some other "nationally important" reasons, and that's why the investment wasn't there up front, and we are left with a design compromise. Other than the fact that this is always the case in aviation, or any other manufacture for that matter, the poorly supported local aircraft industry is following the investment capital overseas. Whining about it now won't help, and PT6 protagonists can bleat all they like about their beloved engine, but maybe they just need to get out a bit more?
I would hazard a guess that there has been more PT6 in flight failures/shutdowns than the RR250 anyway.
The PT6 is under engineered, uses far to much fuel for the power produced making it IMO inefficient. The only advantage is the ability for maintenance to be performed on the hot section without having to remove the whole engine making it preferred by engineers over the likes of a Garrett. I don't care what a 'mechanic' likes to work on, I prefer something that is robust, reliable and offers efficiency.
The PT6 is under engineered, uses far to much fuel for the power produced making it IMO inefficient. The only advantage is the ability for maintenance to be performed on the hot section without having to remove the whole engine making it preferred by engineers over the likes of a Garrett. I don't care what a 'mechanic' likes to work on, I prefer something that is robust, reliable and offers efficiency.
Just what to do with the Nomad design is a quandry. Put in PT6s and you have a twin otter, and that aircraft itself is going back into production (or so sayeth the brochures). I would imagine Gippy is awaiting to see the certification basis of the viking twin otter, and to see if it is honoured by other certificating authorities. It is difficult to see the FAA not insisting on the commuter provisions in FAR23, which will make it a whole new ball game both for twin otter and Nomad. The current aeroplane can't take anymore power, but that matters little as the real problem with power in Nomad, was the negligible flat rate, and the B17F will go a long way to fixing that. On a cold day, the current nomad goes like a rocket. On a hot day its a slug. I knew/know all the GAF and ASTA test pilots, and none ever imagined the Nomad being fitted with PT6s ...well not till after the third bottle of red
Silly Old Git
Hoggsnort I um.. never compared the Nomad to anything
I don't know that there is anything to compare it to size wise is there?
I just got in it, droned around as required, and then went home
I don't know that there is anything to compare it to size wise is there?
I just got in it, droned around as required, and then went home
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Noise makers:
I knew/know all the GAF and ASTA test pilots, and none ever imagined the Nomad being fitted with PT6s ...well not till after the third bottle of red
Water Front bar Villa "circa 1987" Air Melanesia
[COLOR="Black"]Maybe you could PM me with a few names, from the era!
As for engines, It doesn't really matter what they are as long as they are, #1 reliable, and #2 suited to the machine and the multiple environments this sort of machine would operate in:
From a modest & respectable personal experience level, with circa 10k behind a pair of PT6's, from around the pacific, the US, Europe, Africa and the normal weather & seasonal extremes, with the odd irregularity, it is I think fair to say the PT-6s are in a class of their own for operating in some very harsh and often extreme environments, even at times to the point of still running with worn power turbines, "excess tip clearances" bought about by posted down in the field and operating in desert sand.
They have routinely been operated in conditions above their OAT 50 deg C operating limitation:
I have seen routinely, hot sections being replaced with the engine on the wing.
We still flew, when the Jet Rangers would not, due to too much sand in the air, and they had better particle separators than us with out problematic deflector vanes!
From flying the Nomad, I still think the original concept as brilliant:
I have seen the problems associated from operating Garrett's, on the 228, and the Cassa 212 in these environments, and every operator that came into the theatre with this equipment either lost their contracts due to not being able to comply with the contracts serviceability, or changed to Dhc-6's, B200, B 1900:
I understand that the latest Casa 212 has PT-6's.
And no I have never operated/or seen a Nomad operated in such as above, only down in NZ in the winter at night!
I think the question needs to be asked, what is the market the Nomad is aiming at, and against what, is its opposition, and what sort of role is it being offered to support.
That said, and the attached with help from Wiki!
Allison Model 250
From Wikipedia, the free encyclopedia
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Model 250 / T63
MTU-built Allison 250-C20B
Type Turboshaft
National origin United States
Manufacturer Allison Engine CompanyRolls-Royce plc
Major applications Bell 206MD Helicopters MD 500MBB Bo 105Sikorsky S-76
Number built >30,000
The Allison Model 250 (US military designations T63 and T703) is a highly successful turboshaft engine family, originally developed by the Allison Engine Company in the early 1960s. The Model 250 has been produced by Rolls-Royce since it acquired Allison in 1995.
Contents[hide]· 1 Design and development· 2 Variants· 3 Applications· 4 See also· 5 References· 6 External links
[edit] Design and development
Allison adopted a reverse airflow engine configuration for the Model 250: although air enters the intake/compression system in the conventional fashion, the compressed air leaving the centrifugal compressor diffuser is ducted rearwards around the turbine system, before being turned through 180 degrees at entry to the combustor; the combustion products expand through the two stage HP turbine, which is connected, via the HP shaft, to the compression system, before expanding through the two stage power turbine; the exhaust gases then turn though 90 degrees to exit the engine in a radial direction; a stub shaft connects the power turbine to a compact reduction gearbox, located inboard, between the centrifugal compressor and the exhaust/power turbine system.
One of the latest versions of the Model 250 is the -C40, which has a hi-tech centrifugal compressor pulling a pressure ratio of 9.2:1, at an airflow 6.1 lb/s (2.8 kg/s), and developing 715 shp (533 kW).
Some of the earlier versions have axial compressor stages mounted on the HP shaft to supercharge a relatively low pressure ratio centrifugal compressor. The -C20R is typical, pulling an overall pressure ratio of 8.0:1, at an airflow of 4.0 lb/s (1.8 kg/s), with a power output of 450 shp (336 kW).
The Model 250 propels a large number of helicopters and small aircraft.[1] As a result, nearly 30,000 Model 250 engines have been produced. Of these, approximately 16,000 remain in service. The Model 250 is one of the highest-selling engines made by Rolls-Royce.
[edit] Variants
250-C18250-C18A250-C20250-C20B250-C20F250-C20J250-C20R250-C20R/1250-C20R/2250-C20R/4250-C20S250-C20W250-C22B250-C28250-C28B 250-C28C250-C30250-C30G250-C30G/2250-C30M250-C30P250-C30R250-C30R/3250-C30R/3M250-C30S250-C30U250-C34250-C40B250-C47B250-C47M 250-B15250-B15A250-B15C250-B17250-B17B250-B17C250-B17D250-B17F250-B17F/1250-B17F/2T63A-5T63A-5AT63A-700T63A-720T703AD-700
[edit] Applications
· Agusta A109A· Bell 206B/L/LT· Bell 407· Bell 230· Bell 430· Bell OH-58 Kiowa· Cicaré CH-14 · Enstrom 480· Eurocopter AS355F· Extra EA-500· Hughes OH-6 Cayuse· MBB Bo 105· MD Helicopters MD 500· MD Helicopters MD 600 · MD 500 Defender· MH-6 Little Bird· MTT Turbine SUPERBIKE· Schweizer 330, 330SP· Schweizer S-333· Sikorsky S-76
Pratt & Whitney Canada PT6
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PT6
A PT6A-20 on display at the Canada Aviation Museum
Type Turboshaft
National origin Canada
Manufacturer Pratt & Whitney Canada
Major applications Beechcraft Super King Airde Havilland Canada DHC-6 Twin OtterPilatus PC-12Sikorsky S-76
Variants Pratt & Whitney Canada PT6T
The Pratt & Whitney Canada PT6 is one of the most popular turboprop aircraft engines in history.[1] It is produced by Pratt & Whitney Canada in a wide variety of models, covering the power range between 580 and 920 shaft horsepower in the original series, and up to 1,940 shp (1,450 kW) in the "large" lines. The PT6 family are particularly well known for their extremely high reliability, with MTBO's on the order of 9000 hours in some models.[2] In US military use, they are designated as T74 or T101.
Contents[hide]· 1 Design and development· 2 Variants o 2.1 PT6Ao 2.2 PT6Bo 2.3 PT6Co 2.4 PT6Do 2.5 ST6· 3 Applications o 3.1 PT6Ao 3.2 PT6Bo 3.3 PT6Co 3.4 PT6Do 3.5 ST6· 4 Specifications· 5 See also· 6 References· 7 External links
[edit] Design and development
Development of the PT6 family started in the late 1950s, apparently as a modern replacement[citation needed] for the Pratt & Whitney Wasp radial engines they were producing at that time. It first flew on 30 May 1961, mounted on a Beech 18 aircraft at de Havilland Canada's Downsview, Ontario facility. Full-scale production started in 1963, entering service the next year. By its 40th anniversary in 2001 over 36,000 PT6As had been delivered, not including the other versions.[3] The engine is used in over 100 different applications.
The engine consists of two sections that can be easily separated for maintenance. In the gas-generator section air enters through a grill into the low-pressure three-stage axial compressor, then into a single-stage centrifugal compressor, through the annular reverse-flow combustion chamber, and finally through a single-stage turbine that powers the compressors at about 45,000 rpm. Some power is also taken from the compressor end of the shaft to power an accessories section, which also loads the engine when idle to keep it from racing out of control. The hot gas from the gas generator section then flows into a separate power section of the engine, containing a single-stage turbine driving the power take-off system at about 30,000 rpm. For turboprop use, this powers a two-stage planetary output reduction gearbox, which turns the propeller at a speed of 1,900 to 2,200 rpm. The exhaust gas then escapes through two side mounted ducts in the power turbine housing, and is directed away from the engine in order to provide about 600 lbf (2,700 N) of jet thrust. The engine is arranged such that the power turbines are mounted inside the combustion chamber, reducing overall length.
Reduction gears on Pratt & Whitney Canada PT6 gas turbine engine.
In most aircraft installations the PT6 is mounted backwards in the nacelle, so that the intake side of the engine is facing the rear of the aircraft. This places the power section at the front of the nacelle, where it can drive the propeller directly without the need for a long shaft. Intake air is usually fed to the engine via an underside mounted duct, and the two exhaust outlets are directed rearward. This arrangement also aids maintenance by allowing the entire power section to be removed along with the propeller, exposing the gas-generator section.
Several other versions of the PT6 have appeared over time. The PT6A large added an additional power turbine stage and a deeper output reduction, producing almost twice the power output, between 1,090 and 1,920 shp (1,430 kW). The PT6B is a helicopter turboshaft model, featuring an offset reduction gearbox with a freewheeling clutch and power turbine governor, producing 1,000 hp (750 kW) at 4,500 rpm. The PT6C is a helicopter model, with a single side-mounted exhaust, producing 2,000 hp (1,500 kW) at 30,000 rpm, which is stepped down in a user-supplied gearbox. The PT6T Twin-Pac consists of two PT6 engines driving a common output reduction gearbox, producing almost 4,000 hp (3,000 kW) at 6,000 rpm. The ST6 is a version intended for stationary applications, originally developed for the UAC TurboTrain, and now widely used as auxiliary power units on large aircraft, as well as many other roles.[4]
When de Havilland Canada asked for a much larger engine, roughly twice the power of the PT6 Large, P&WC responded with a new design initially known as the PT7. During development this was renamed to become the Pratt & Whitney Canada PW100.
[edit] Variants
[edit] PT6A
A PT6A-67D engine on a Beechcraft 1900D. The jet nozzle on the exhaust is prominent.
The PT6A is a free turbine providing 500 to 1,940 shaft horsepower (433 to 1,447 kW).
PT6A-6
"Small" engine of 525 equivalent shaft horsepower (eshp) and 500 shaft horsepower (shp)[5]
PT6A-11
"Small" engine of 528 eshp and 500 shp[5]
PT6A-15AG
"Small" engine optimised for agricultural aircraft of 715 eshp and 680 shp[5]
PT6A-20
"Small" engine of 579 eshp and 550 shp[5]
PT6A-21
"Small" engine of 580 eshp and 550 shp[5]
PT6A-25
"Small" engine of 580 eshp and 550 shp (-25, -25A) or 783 eshp and 750 shp (-25C)[5]
PT6A-27
"Small" engine of 715 eshp and 680 shp[5]
PT6A-28
"Small" engine of 715 eshp and 680 shp[5]
PT6A-29
"Small" engine of 778 eshp and 750 shp[5]
PT6A-34
"Small" engine of 783 eshp and 750 shp[5]
PT6A-35
"Small" engine of 787 eshp and 750 shp[5]
PT6A-36
"Small" engine of 783 eshp and 750 shp[5]
PT6A-38
"Large" engine of 801 eshp and 750 shp[5]
PT6A-40
"Large" engine of 749 eshp and 700 shp[5]
PT6A-41
"Large" engine of 903 eshp and 850 shp[5]
PT6A-42
"Large" engine of 903 eshp and 850 shp[5]
PT6A-45
"Large" engine of 1,070 eshp and 1,020 shp[5]
PT6A-50
"Large" engine of 1,022 eshp and 973 shp[5]
PT6A-52
"Large" engine of 898 eshp and 850 shp[5]
PT6A-60
"Large" engine of 1,113 eshp and 1,050 shp (-60, -60A) or 1,081 ehsp and 1,020 shp (-60AG)[5]
PT6A-61
"Large" engine of 902 eshp and 850 shp[5]
PT6A-62
"Large" engine of 1,218 eshp and 950 shp[6]
PT6A-64
"Large" engine of 747 eshp and 700 shp[7]
PT6A-65
"Large" engine of 1,249 eshp and 1,173 shp (-65B, -65R) or 1,298 eshp and 1,220 shp (-65AG, -65AR)[5]
PT6A-66
"Large" engine of 905 eshp and 850 shp (-66, -66A, -66D) or 1,010 eshp and 950 shp (-66B)[7]
PT6A-67
"Large" engine of 1,272 eshp and 1,200 shp (-67, -67A, -67B, -67P), 1,285 eshp and 1,214 shp (-67D), 1,294 eshp and 1,220 shp (-67AF, -67AG, -67R, -67T), or 1,796 eshp and 1,700 shp (-67F)[7]
PT6A-68
"Large" engine of 1,324 eshp and 1,250 shp[7]
PT6A-110
"Small" engine of 502 eshp and 475 shp[5]
PT6A-112
"Small" engine of 528 eshp and 500 shp[5]
PT6A-114
"Small" engine of 632 eshp and 600 shp (-114) or 725 eshp and 675 shp (-114A)[5]
PT6A-116
"Small" engine of 736 eshp and 700 shp[5]
PT6A-121
"Small" engine of 647 eshp and 615 shp[5]
PT6A-135
"Small" engine of 787 eshp and 750 shp[5]
[edit] PT6B
The PT6B is a 981 horsepower (732 kW) engine designed for helicopters.
[edit] PT6C
The PT6C is a 1600 to 2300 horsepower (1190 to 1720 kW) engine for helicopters and tiltrotors.
[edit] PT6D
The PT6D-114A is based on the PT6A-114A. The main difference is the deletion of the second stage reduction gearing and output shaft, as the engine is intended for integration with a combining gearbox incorporated power turbine governors and a propeller output shaft.[8]
[edit] ST6
The ST6 is a variant of the PT6 that was originally developed as a powerplant for the UAC TurboTrain locomotives, but later developed as a stationary power generator and auxiliary power unit.
[edit] Applications
[edit] PT6A
· AASI Jetcruzer· Aero Commander 680T (PT6 conversion)· Aero Ae 270 Ibis· Air Tractor AT-400· Air Tractor AT-501· Air Tractor AT-602· Air Tractor AT-802· Antilles Super Goose· Antonov An-28· Ayres Turbo Thrush· Basler BT-67· Beechcraft 1900· Beechcraft A36TC Bonanza (turbine conversion)· Beechcraft C-12 Huron· Beechcraft King Air· Beechcraft Lightning· Beech 18 series (turbine conversion)· Beechcraft Model 87· Beechcraft Model 99· Beechcraft RC-12 Guardrail· Beechcraft RU-21C Ute· Beechcraft Starship· Beechcraft Super King Air· Beechcraft T-6 Texan II· Beechcraft T-34C Turbo-Mentor· Beechcraft T-44 Pegasus· CASA C-212 series 300P· Cessna 208 Caravan· Cessna P210N (turbine conversion)· Cessna 404 Titan (turbine conversion)· Cessna 421C Golden Eagle (turbine conversion)· Cessna 425 Corsair/Conquest I· Conair Turbo Firecat· Conroy Tri-Turbo-Three· de Havilland Canada DHC-2 Mk. III Turbo Beaver· de Havilland Canada DHC-3 Otter (turbine conversions)· de Havilland Canada DHC-6 Twin Otter· de Havilland Canada Dash 7· Dominion UV-23 Scout· Dornier Do 128 Turbo Skyservant· Dornier Seawings Seastar· Douglas DC-3 (turbine conversions)· Embraer EMB 110 Bandeirante · Embraer EMB 121 Xingu· Embraer EMB 312 Tucano· Embraer EMB 314 Super Tucano· Frakes Mohawk 298· Frakes Turbocat· Gulfstream American Hustler 400· Grumman Mallard (turbine conversion)· Grumman Goose (turbine conversion)· Harbin Y-12· Helio AU-24 Stallion· IAI Arava· IAI Eitan· JetPROP DLX· KAI KT-1· Let L-410 Turbolet· NAL Saras· NDN Fieldmaster· FTS Turbo Firecracker· PAC 750XL· PAC Cresco· Piaggio P.180 Avanti· Pilatus PC-6/B Turbo-Porter· Pilatus PC-7· Pilatus PC-9· Pilatus PC-12· Pilatus PC-21· Piper PA-31P (turbine conversion)· Piper PA-31T Cheyenne· Piper PA-42 Cheyenne III· Piper PA-46-500TP Meridian· Piper T1040· PZL-130T Turbo Orlik and PZL-130TC-II Orlik· PZL M-18 Dromader (turbine conversion)· PZL M28 Skytruck· Quest Kodiak· Reims-Cessna F406 Caravan II· Saunders ST-27/ST-28· Scaled Composites ATTT· Shorts 330· Shorts 360· Short C-23 Sherpa· Socata TBM· Spectrum SA-550· Swearingen SA26-T Merlin IIA
[edit] PT6B
· AgustaWestland AW119 Koala
· Sikorsky S-76B
· Changhe Z-8F: License-built Chinese version of the Aérospatiale SA321 Super Frelon helicopter fitted with PT6B-67A turboshaft engines
[edit] PT6C
· AgustaWestland AW139
· Bell/Agusta BA609
[edit] PT6D
· Soloy Pathfinder 21
Chr's
H/Snort:
PS: The new Viking 400 series Otter is a great machine, however I do have doubts as to its modernization perhaps being its weak point, and I only hope it is equally up to the old steam driven machines reliability.
Water Front bar Villa "circa 1987" Air Melanesia
[COLOR="Black"]Maybe you could PM me with a few names, from the era!
As for engines, It doesn't really matter what they are as long as they are, #1 reliable, and #2 suited to the machine and the multiple environments this sort of machine would operate in:
From a modest & respectable personal experience level, with circa 10k behind a pair of PT6's, from around the pacific, the US, Europe, Africa and the normal weather & seasonal extremes, with the odd irregularity, it is I think fair to say the PT-6s are in a class of their own for operating in some very harsh and often extreme environments, even at times to the point of still running with worn power turbines, "excess tip clearances" bought about by posted down in the field and operating in desert sand.
They have routinely been operated in conditions above their OAT 50 deg C operating limitation:
I have seen routinely, hot sections being replaced with the engine on the wing.
We still flew, when the Jet Rangers would not, due to too much sand in the air, and they had better particle separators than us with out problematic deflector vanes!
From flying the Nomad, I still think the original concept as brilliant:
I have seen the problems associated from operating Garrett's, on the 228, and the Cassa 212 in these environments, and every operator that came into the theatre with this equipment either lost their contracts due to not being able to comply with the contracts serviceability, or changed to Dhc-6's, B200, B 1900:
I understand that the latest Casa 212 has PT-6's.
And no I have never operated/or seen a Nomad operated in such as above, only down in NZ in the winter at night!
I think the question needs to be asked, what is the market the Nomad is aiming at, and against what, is its opposition, and what sort of role is it being offered to support.
That said, and the attached with help from Wiki!
Allison Model 250
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Model 250 / T63
MTU-built Allison 250-C20B
Type Turboshaft
National origin United States
Manufacturer Allison Engine CompanyRolls-Royce plc
Major applications Bell 206MD Helicopters MD 500MBB Bo 105Sikorsky S-76
Number built >30,000
The Allison Model 250 (US military designations T63 and T703) is a highly successful turboshaft engine family, originally developed by the Allison Engine Company in the early 1960s. The Model 250 has been produced by Rolls-Royce since it acquired Allison in 1995.
Contents[hide]· 1 Design and development· 2 Variants· 3 Applications· 4 See also· 5 References· 6 External links
[edit] Design and development
Allison adopted a reverse airflow engine configuration for the Model 250: although air enters the intake/compression system in the conventional fashion, the compressed air leaving the centrifugal compressor diffuser is ducted rearwards around the turbine system, before being turned through 180 degrees at entry to the combustor; the combustion products expand through the two stage HP turbine, which is connected, via the HP shaft, to the compression system, before expanding through the two stage power turbine; the exhaust gases then turn though 90 degrees to exit the engine in a radial direction; a stub shaft connects the power turbine to a compact reduction gearbox, located inboard, between the centrifugal compressor and the exhaust/power turbine system.
One of the latest versions of the Model 250 is the -C40, which has a hi-tech centrifugal compressor pulling a pressure ratio of 9.2:1, at an airflow 6.1 lb/s (2.8 kg/s), and developing 715 shp (533 kW).
Some of the earlier versions have axial compressor stages mounted on the HP shaft to supercharge a relatively low pressure ratio centrifugal compressor. The -C20R is typical, pulling an overall pressure ratio of 8.0:1, at an airflow of 4.0 lb/s (1.8 kg/s), with a power output of 450 shp (336 kW).
The Model 250 propels a large number of helicopters and small aircraft.[1] As a result, nearly 30,000 Model 250 engines have been produced. Of these, approximately 16,000 remain in service. The Model 250 is one of the highest-selling engines made by Rolls-Royce.
[edit] Variants
250-C18250-C18A250-C20250-C20B250-C20F250-C20J250-C20R250-C20R/1250-C20R/2250-C20R/4250-C20S250-C20W250-C22B250-C28250-C28B 250-C28C250-C30250-C30G250-C30G/2250-C30M250-C30P250-C30R250-C30R/3250-C30R/3M250-C30S250-C30U250-C34250-C40B250-C47B250-C47M 250-B15250-B15A250-B15C250-B17250-B17B250-B17C250-B17D250-B17F250-B17F/1250-B17F/2T63A-5T63A-5AT63A-700T63A-720T703AD-700
[edit] Applications
· Agusta A109A· Bell 206B/L/LT· Bell 407· Bell 230· Bell 430· Bell OH-58 Kiowa· Cicaré CH-14 · Enstrom 480· Eurocopter AS355F· Extra EA-500· Hughes OH-6 Cayuse· MBB Bo 105· MD Helicopters MD 500· MD Helicopters MD 600 · MD 500 Defender· MH-6 Little Bird· MTT Turbine SUPERBIKE· Schweizer 330, 330SP· Schweizer S-333· Sikorsky S-76
Pratt & Whitney Canada PT6
From Wikipedia, the free encyclopedia
Jump to: navigation, search
PT6
A PT6A-20 on display at the Canada Aviation Museum
Type Turboshaft
National origin Canada
Manufacturer Pratt & Whitney Canada
Major applications Beechcraft Super King Airde Havilland Canada DHC-6 Twin OtterPilatus PC-12Sikorsky S-76
Variants Pratt & Whitney Canada PT6T
The Pratt & Whitney Canada PT6 is one of the most popular turboprop aircraft engines in history.[1] It is produced by Pratt & Whitney Canada in a wide variety of models, covering the power range between 580 and 920 shaft horsepower in the original series, and up to 1,940 shp (1,450 kW) in the "large" lines. The PT6 family are particularly well known for their extremely high reliability, with MTBO's on the order of 9000 hours in some models.[2] In US military use, they are designated as T74 or T101.
Contents[hide]· 1 Design and development· 2 Variants o 2.1 PT6Ao 2.2 PT6Bo 2.3 PT6Co 2.4 PT6Do 2.5 ST6· 3 Applications o 3.1 PT6Ao 3.2 PT6Bo 3.3 PT6Co 3.4 PT6Do 3.5 ST6· 4 Specifications· 5 See also· 6 References· 7 External links
[edit] Design and development
Development of the PT6 family started in the late 1950s, apparently as a modern replacement[citation needed] for the Pratt & Whitney Wasp radial engines they were producing at that time. It first flew on 30 May 1961, mounted on a Beech 18 aircraft at de Havilland Canada's Downsview, Ontario facility. Full-scale production started in 1963, entering service the next year. By its 40th anniversary in 2001 over 36,000 PT6As had been delivered, not including the other versions.[3] The engine is used in over 100 different applications.
The engine consists of two sections that can be easily separated for maintenance. In the gas-generator section air enters through a grill into the low-pressure three-stage axial compressor, then into a single-stage centrifugal compressor, through the annular reverse-flow combustion chamber, and finally through a single-stage turbine that powers the compressors at about 45,000 rpm. Some power is also taken from the compressor end of the shaft to power an accessories section, which also loads the engine when idle to keep it from racing out of control. The hot gas from the gas generator section then flows into a separate power section of the engine, containing a single-stage turbine driving the power take-off system at about 30,000 rpm. For turboprop use, this powers a two-stage planetary output reduction gearbox, which turns the propeller at a speed of 1,900 to 2,200 rpm. The exhaust gas then escapes through two side mounted ducts in the power turbine housing, and is directed away from the engine in order to provide about 600 lbf (2,700 N) of jet thrust. The engine is arranged such that the power turbines are mounted inside the combustion chamber, reducing overall length.
Reduction gears on Pratt & Whitney Canada PT6 gas turbine engine.
In most aircraft installations the PT6 is mounted backwards in the nacelle, so that the intake side of the engine is facing the rear of the aircraft. This places the power section at the front of the nacelle, where it can drive the propeller directly without the need for a long shaft. Intake air is usually fed to the engine via an underside mounted duct, and the two exhaust outlets are directed rearward. This arrangement also aids maintenance by allowing the entire power section to be removed along with the propeller, exposing the gas-generator section.
Several other versions of the PT6 have appeared over time. The PT6A large added an additional power turbine stage and a deeper output reduction, producing almost twice the power output, between 1,090 and 1,920 shp (1,430 kW). The PT6B is a helicopter turboshaft model, featuring an offset reduction gearbox with a freewheeling clutch and power turbine governor, producing 1,000 hp (750 kW) at 4,500 rpm. The PT6C is a helicopter model, with a single side-mounted exhaust, producing 2,000 hp (1,500 kW) at 30,000 rpm, which is stepped down in a user-supplied gearbox. The PT6T Twin-Pac consists of two PT6 engines driving a common output reduction gearbox, producing almost 4,000 hp (3,000 kW) at 6,000 rpm. The ST6 is a version intended for stationary applications, originally developed for the UAC TurboTrain, and now widely used as auxiliary power units on large aircraft, as well as many other roles.[4]
When de Havilland Canada asked for a much larger engine, roughly twice the power of the PT6 Large, P&WC responded with a new design initially known as the PT7. During development this was renamed to become the Pratt & Whitney Canada PW100.
[edit] Variants
[edit] PT6A
A PT6A-67D engine on a Beechcraft 1900D. The jet nozzle on the exhaust is prominent.
The PT6A is a free turbine providing 500 to 1,940 shaft horsepower (433 to 1,447 kW).
PT6A-6
"Small" engine of 525 equivalent shaft horsepower (eshp) and 500 shaft horsepower (shp)[5]
PT6A-11
"Small" engine of 528 eshp and 500 shp[5]
PT6A-15AG
"Small" engine optimised for agricultural aircraft of 715 eshp and 680 shp[5]
PT6A-20
"Small" engine of 579 eshp and 550 shp[5]
PT6A-21
"Small" engine of 580 eshp and 550 shp[5]
PT6A-25
"Small" engine of 580 eshp and 550 shp (-25, -25A) or 783 eshp and 750 shp (-25C)[5]
PT6A-27
"Small" engine of 715 eshp and 680 shp[5]
PT6A-28
"Small" engine of 715 eshp and 680 shp[5]
PT6A-29
"Small" engine of 778 eshp and 750 shp[5]
PT6A-34
"Small" engine of 783 eshp and 750 shp[5]
PT6A-35
"Small" engine of 787 eshp and 750 shp[5]
PT6A-36
"Small" engine of 783 eshp and 750 shp[5]
PT6A-38
"Large" engine of 801 eshp and 750 shp[5]
PT6A-40
"Large" engine of 749 eshp and 700 shp[5]
PT6A-41
"Large" engine of 903 eshp and 850 shp[5]
PT6A-42
"Large" engine of 903 eshp and 850 shp[5]
PT6A-45
"Large" engine of 1,070 eshp and 1,020 shp[5]
PT6A-50
"Large" engine of 1,022 eshp and 973 shp[5]
PT6A-52
"Large" engine of 898 eshp and 850 shp[5]
PT6A-60
"Large" engine of 1,113 eshp and 1,050 shp (-60, -60A) or 1,081 ehsp and 1,020 shp (-60AG)[5]
PT6A-61
"Large" engine of 902 eshp and 850 shp[5]
PT6A-62
"Large" engine of 1,218 eshp and 950 shp[6]
PT6A-64
"Large" engine of 747 eshp and 700 shp[7]
PT6A-65
"Large" engine of 1,249 eshp and 1,173 shp (-65B, -65R) or 1,298 eshp and 1,220 shp (-65AG, -65AR)[5]
PT6A-66
"Large" engine of 905 eshp and 850 shp (-66, -66A, -66D) or 1,010 eshp and 950 shp (-66B)[7]
PT6A-67
"Large" engine of 1,272 eshp and 1,200 shp (-67, -67A, -67B, -67P), 1,285 eshp and 1,214 shp (-67D), 1,294 eshp and 1,220 shp (-67AF, -67AG, -67R, -67T), or 1,796 eshp and 1,700 shp (-67F)[7]
PT6A-68
"Large" engine of 1,324 eshp and 1,250 shp[7]
PT6A-110
"Small" engine of 502 eshp and 475 shp[5]
PT6A-112
"Small" engine of 528 eshp and 500 shp[5]
PT6A-114
"Small" engine of 632 eshp and 600 shp (-114) or 725 eshp and 675 shp (-114A)[5]
PT6A-116
"Small" engine of 736 eshp and 700 shp[5]
PT6A-121
"Small" engine of 647 eshp and 615 shp[5]
PT6A-135
"Small" engine of 787 eshp and 750 shp[5]
[edit] PT6B
The PT6B is a 981 horsepower (732 kW) engine designed for helicopters.
[edit] PT6C
The PT6C is a 1600 to 2300 horsepower (1190 to 1720 kW) engine for helicopters and tiltrotors.
[edit] PT6D
The PT6D-114A is based on the PT6A-114A. The main difference is the deletion of the second stage reduction gearing and output shaft, as the engine is intended for integration with a combining gearbox incorporated power turbine governors and a propeller output shaft.[8]
[edit] ST6
The ST6 is a variant of the PT6 that was originally developed as a powerplant for the UAC TurboTrain locomotives, but later developed as a stationary power generator and auxiliary power unit.
[edit] Applications
[edit] PT6A
· AASI Jetcruzer· Aero Commander 680T (PT6 conversion)· Aero Ae 270 Ibis· Air Tractor AT-400· Air Tractor AT-501· Air Tractor AT-602· Air Tractor AT-802· Antilles Super Goose· Antonov An-28· Ayres Turbo Thrush· Basler BT-67· Beechcraft 1900· Beechcraft A36TC Bonanza (turbine conversion)· Beechcraft C-12 Huron· Beechcraft King Air· Beechcraft Lightning· Beech 18 series (turbine conversion)· Beechcraft Model 87· Beechcraft Model 99· Beechcraft RC-12 Guardrail· Beechcraft RU-21C Ute· Beechcraft Starship· Beechcraft Super King Air· Beechcraft T-6 Texan II· Beechcraft T-34C Turbo-Mentor· Beechcraft T-44 Pegasus· CASA C-212 series 300P· Cessna 208 Caravan· Cessna P210N (turbine conversion)· Cessna 404 Titan (turbine conversion)· Cessna 421C Golden Eagle (turbine conversion)· Cessna 425 Corsair/Conquest I· Conair Turbo Firecat· Conroy Tri-Turbo-Three· de Havilland Canada DHC-2 Mk. III Turbo Beaver· de Havilland Canada DHC-3 Otter (turbine conversions)· de Havilland Canada DHC-6 Twin Otter· de Havilland Canada Dash 7· Dominion UV-23 Scout· Dornier Do 128 Turbo Skyservant· Dornier Seawings Seastar· Douglas DC-3 (turbine conversions)· Embraer EMB 110 Bandeirante · Embraer EMB 121 Xingu· Embraer EMB 312 Tucano· Embraer EMB 314 Super Tucano· Frakes Mohawk 298· Frakes Turbocat· Gulfstream American Hustler 400· Grumman Mallard (turbine conversion)· Grumman Goose (turbine conversion)· Harbin Y-12· Helio AU-24 Stallion· IAI Arava· IAI Eitan· JetPROP DLX· KAI KT-1· Let L-410 Turbolet· NAL Saras· NDN Fieldmaster· FTS Turbo Firecracker· PAC 750XL· PAC Cresco· Piaggio P.180 Avanti· Pilatus PC-6/B Turbo-Porter· Pilatus PC-7· Pilatus PC-9· Pilatus PC-12· Pilatus PC-21· Piper PA-31P (turbine conversion)· Piper PA-31T Cheyenne· Piper PA-42 Cheyenne III· Piper PA-46-500TP Meridian· Piper T1040· PZL-130T Turbo Orlik and PZL-130TC-II Orlik· PZL M-18 Dromader (turbine conversion)· PZL M28 Skytruck· Quest Kodiak· Reims-Cessna F406 Caravan II· Saunders ST-27/ST-28· Scaled Composites ATTT· Shorts 330· Shorts 360· Short C-23 Sherpa· Socata TBM· Spectrum SA-550· Swearingen SA26-T Merlin IIA
[edit] PT6B
· AgustaWestland AW119 Koala
· Sikorsky S-76B
· Changhe Z-8F: License-built Chinese version of the Aérospatiale SA321 Super Frelon helicopter fitted with PT6B-67A turboshaft engines
[edit] PT6C
· AgustaWestland AW139
· Bell/Agusta BA609
[edit] PT6D
· Soloy Pathfinder 21
Chr's
H/Snort:
PS: The new Viking 400 series Otter is a great machine, however I do have doubts as to its modernization perhaps being its weak point, and I only hope it is equally up to the old steam driven machines reliability.
Join Date: Jun 2008
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One 'l' only in Port Vila - and Air Melanesiae had an 'e' . 
"I" was never in it, but knew the 'Boz' - as someone said on the Susi thread - 'Single Boz Concept'
AsAero - Put new technology Turbo-Diesels of about 500 h.p. in, (or a couple of the new R-R RR500TP's if installed engine weight is a problem, and they run on diesel as well) - IF there is still a market slot where it will fit. The 22 had a nice boxy fuselage for cargo and WAS STOL when the Allisons were outputing all their power. Not so sure the undercarriage needs to go up and down, considering the little speed gained for the complexity involved and its basic role.
"I" was never in it, but knew the 'Boz' - as someone said on the Susi thread - 'Single Boz Concept'
AsAero - Put new technology Turbo-Diesels of about 500 h.p. in, (or a couple of the new R-R RR500TP's if installed engine weight is a problem, and they run on diesel as well) - IF there is still a market slot where it will fit. The 22 had a nice boxy fuselage for cargo and WAS STOL when the Allisons were outputing all their power. Not so sure the undercarriage needs to go up and down, considering the little speed gained for the complexity involved and its basic role.
Last edited by frigatebird; 29th Dec 2009 at 00:38.
I knew that!