|WikiProject Aviation / Aircraft engines||(Rated C-class)|
|Wikipedia Version 1.0 Editorial Team||(Rated Start-class)|
- 1 First Turboprop Aircraft
- 2 Turboprop illustration
- 3 Merge
- 4 Efficiency versus Piston Engine?
- 5 Soviet Tech
- 6 Version 0.7 review
- 7 Top speed of turboprop?
- 8 Compressors
- 9 Electra Technology
- 10 Turboprop market information
- 11 Name too short
- 12 too slow to be turbo
- 13 Current Engines
- 14 1:1 Reduction Gear
- 15 thrust-values?
- 16 temperature of the exhaust gas stream?
- 17 thrust-to-weight-ratio
First Turboprop Aircraft
"The first turboprop engine was the Rolls-Royce RB.50 Trent, a converted Derwent II fitted with reduction gear and a Rotol 7' 11" five-bladed propeller. Two Trents were fitted to Gloster Meteor EE227 - the "Trent-Meteor" - which became the first turboprop powered aircraft."
I've removed the 2nd sentance from the article as the Gloster Meteor article, and pictures, appear to clearly contradict this. Could someone with better knowledge of aircraft write a replacement sentance. --Myfanwy 09:30, 23 Jun 2005 (UTC)
- The Trent-Meteor was a converted Meteor I which had its Derwent jet engines replaced with two of the converted Derwents (Trents) Trent-Meteor It was therefore the worlds first turboprop powered aircraft. I'll add a line or two to the Meteor page stating this and restore the original sentence. Ian Dunster 11:55, 9 November 2005 (UTC)
Copy says that technology from the Lockheed Electra was used in the Lockheed C-130. Not true, it's the other way around. The Hercules preceded the Electra.220.127.116.11 (talk) 21:42, 15 April 2012 (UTC)
I don't understand, why are turboprops more eficient at low velocity, than turbojets?
The efficiency of a turbojet increases as its speed through the air increases, because that forward speed allows for more efficient compression of the air inside the engine. The SR-71's engines, for example, were more efficient (less fuel burned per mile) at Mach 3.2 than at Mach 2.8. The efficiency of a turboprop, however, decreases the fast it goes, because the the fast you go, the propeller must increase in pitch to maintain the same thrust. But because drag is higher, the prop must be increased an additional amount just to overcome that drag. There's a practical limit at any given propeller rotation speed, but you can't just increase the prop rotation speed, as doing so can mean the propeller tips go supersonic, and that not only creates a lot of noise, but it creates a lot of drag, as well. Mugaliens 20:04, 13 August 2006 (UTC)
While the picture is very nice, I can't think of a single turboprop aircraft that angles its exhaust so as to prevent residual thrust. That thrust is beneficial. 18.104.22.168 05:31, 3 January 2006 (UTC)
- Yes, I don't understand that either. --Hooperbloob 23:46, 1 April 2006 (UTC)
- While flying, yes, and it's why the turboprop directs the thrust aft. But the elimination of residual thrust is primarily for ground power units, ship's turboshaft engines, etc. Most have additional turbine sections to scavange nearly all of the pressure differential before the gasses are exhausted, as that's more efficient. But for turboprops, you're right - that residual thrust is beneficial, and about 25% of the thrust comes from it. Mugaliens 20:11, 13 August 2006 (UTC)
- Most PT6 applications do not get any thrust from the exhaust. This is due to the way the engine is built with the intake at the back of the engine and the exhaust at the front. King Airs are great example. While the exhaust does face back, the actual thrust gained from it is negilable since most of the thrust is used to turn the prop and running the generators. Xnuiem 12:47, 19 January 2007 (UTC)
"This enables the propeller to rotate freely, independent of compressor speed." From the current illustration I don't see how this can happen since the prop shaft is geared to the turbine shaft.--Hooperbloob 23:46, 1 April 2006 (UTC)
- The illustration depicts a geared turboprop engine. There is another type of turboprop which isn't illustrated that uses a free power turbine to drive the propeller. 22.214.171.124 06:52, 4 April 2006 (UTC)
Notable mention of the PT6 engine in this talk (above by Xnuiem) but, strangely NO MENTION of reverse-flow engines in the entire article. Considering how common these engines are and how significantly their operation differs from the illustrated flows, they deserve at least some mention - if only to link to the PT6 Wikipedia entry: http://en.wikipedia.org/wiki/Pratt_%26_Whitney_Canada_PT6 . This link is already on the page in the manufacturers table, but there is no indication of the engine's functional difference. — Preceding unsigned comment added by 126.96.36.199 (talk) 02:40, 5 January 2015 (UTC)
Disagree... they are different things. Turboprop=geared off main shaft. Turboshaft=different shaft. See Turboshaft. 00:11, 24 July 2006 (UTC)~
Disagree with the proposed merger. Turboprops are a gas-turbine engine who's principle work drives a propeller connected directly to the engine via mechanical gearing. It's almost always a constant-speed prop, and as the throttles are advanced or retarded, the pitch is changed to maintain a constant rotational velocity. A turboshaft, on the other hand, generates an exhaust stream that drives an impeller which may or may not be coaxial with the engine. That impeller is in turn connected to generators, air blowers, the shafts of a ship's props, a helicopter's rotor blades, etc. The key difference is that a turboprop is constant speed, while the devices a turboshaft drives have a need to maintain a variety of rotational velocities, or will see a variety of changing loads. Mugaliens 19:56, 13 August 2006 (UTC)
Amazingly, it just hit me - there's another key difference between turboprops and turboshafts. The turboprop drives the aircraft's propeller, (hence, turboprop), while the turboshaft is just the engine itself, and can drive many different things. So again, do not merge. Rather, both need to be cleaned up to reflect this. Mugaliens 10:34, 20 August 2006 (UTC)
By the way, I think this idea has been killed. Let's remove the proposed merger sign. Mugaliens 10:36, 20 August 2006 (UTC)
- Actually 'turboprop' is just short for Turbo-Propeller in contrast to Turbo-Jet, the original wordings, later shortened, the difference between a 'Turbo-Prop' and a 'Turbo-Shaft' just being in the power take-off, the turboprop being geared to a propeller, the turboshaft to a drive shaft and then (usually) to some sort of gearbox. The use of the term 'turboprop' in a helicopter or ship being somewhat misleading and inaccurate, therefore the use of the term turboshaft. Basically they are the same type of engine, for example, the Bristol Proteus was available in both turboprop and marine (turboshaft) versions. —Preceding unsigned comment added by 188.8.131.52 (talk • contribs)
Efficiency versus Piston Engine?
However, turboprops are far more efficient than piston-driven propeller engines.
BSFC for a piston airplane engine is typically around 0.45 lb/hp-h while BSFC for a turboprop it is typically around 0.65 lb/hp-h. So the above statement is not true when referring to fuel efficiency. However, the overwhelming popularity of turboprops for commercial aviation applications suggests that overall efficiency (taking into consideration all costs) is better.
The above statement should either be removed or, more beneficially, expanded into a fuller discussion of the overall difference in cost of the two types of engines.
- I removed it for now. Frankly, it's been so long since large aircraft were designed with piston engines that it's hard to know how efficient a large piston airliner would be. My guess would be "probably a fair bit more efficient", but the big barrier is safety. Turboprops and turbofans are incredibly reliable; piston engines were less so back in the old days. --Robert Merkel 05:32, 31 October 2006 (UTC)
- Turboprops generally aren't more efficient than piston engine aircraft, but they have much longer TBO's. Turboprops can be more efficient, but that requires a higher compression ratio than their small scale centrifugal compressors can provide. It boils down to maintenance...one spinning shaft is easier and cheaper to maintain than a concert of reciprocating parts. LostCause (talk) 02:14, 7 April 2008 (UTC)
- Doesn't power-to-weight ratio figure in too? Turboprops weigh a lot less than piston engines producing the same power - this has to figure into the advantages somewhere. It does make the aircraft lighter overall, which, given the same power rating, would gain back a bit of the efficiency lost to highr fuel consumption. - BillCJ (talk) 02:34, 7 April 2008 (UTC)
- Turboprops use less-expensive kerosene fuel which is much cheaper than aviation gasoline. This means cheaper fuel bills for the operator. Also while a new turboprop engine will not have an especially high TBO on entering service, the TBO will usually climb at a much faster rate over time than with a comparable piston engine. In use the engine shut-down rate is also likely to be negligible compared to a large piston engine. — Preceding unsigned comment added by 184.108.40.206 (talk) 11:28, 2 January 2017 (UTC)
The following line might need rewriting:
"While the Soviet Union had the technology to create a jet powered strategic bomber comparable to Boeing's B-52 Stratofortress,"
As I understand it, the Soviets tried and failed, for most of the Cold War era, to build a long-range heavy-load intercontinental jet bomber. This might be an outdated understanding that I've picked up from slightly older material, but I think it's worth a second look. —The preceding unsigned comment was added by 220.127.116.11 (talk) 05:37, 11 May 2007 (UTC).
Version 0.7 review
Thanks for nominating this, but I don't think it's ready yet. There are absolutely no references, and the article seems rather limited for such a broad, major topic - that's why I rated it as Start. A description of the technology is also mixed between the intro and the next section. If the article can be beefed up, we'd like to have this important topic included on the DVD, please renominate. Thanks, Walkerma 03:45, 9 September 2007 (UTC)
Top speed of turboprop?
Currently, turboprop engines are generally used on small subsonic aircraft, but some aircraft outfitted with turboprops have cruising speeds in excess of 500 kt (926 km/h, 575 mph).
- Good question. Fastest propeller-driven aircraft#Turboprops states that the Tupolev Tu-114 holds the speed record for turboprops at 545 mph (not quite 575). There are references on that page for this record, along with other official and non-oficial records by other aircraft. Take a look, and see if you want to change it here. If not, I will see what I can do. - BillCJ (talk) 19:53, 19 September 2008 (UTC)
The first line of the 4th para of the "Technological aspect" say that "most" turbojets contain at least one centrifugal compression stage Can we have a ref/some evidence, please? Of course early designs like the Dart had (wholly) centrifugal compressors, but so did most of their contemporary jets. One should compare like with like. I'm not an engine specialist, but the descriptions of the Allison T56 and the RR Tyne compressors in Jane's AWA 1966 seem to say clearly these are all axial. It would also be interesting to have a specific example of an engine with both axial and centrifugal compressor stages.TSRL (talk) 21:58, 5 December 2008 (UTC)
- Actually, the article says that most turboPROPS contain at least one stage of centrifugal compressor, and I believe this is true. Examples include the Pratt & Whitney Canada PT6 and Garrett AiResearch TPE-331, and the Rolls-Royce Model 250 which is sold in both turboshaft and turboprop versions. There are a few modern turbofan engines that use centrifugal compression, such as the Williams FJ44. Centrifugal compressors were once thought obsolete due to their large size, but that has changed as materials have improved, allowing engineers to design them for higher rotational speeds and get the same compression out of a smaller rotor. Shreditor (talk) 07:09, 6 December 2008 (UTC)
- That first "jet" was indeed a typo. Agree that the three engines you cite have a centrifugal stage (the RR 250 seems to be entirely centrifugal), and that these relatively low output motors have sold very well. I guess they dominate the stats and should have known about them! Is it true that the more powerful turboprops (> 2000 shp say, arbitrarily) have purely axial compressors like those of the Tyne and T56, or are there centrifugal compressor engines in this class too? It would be worth expanding the original comments to make these points and include refs.TSRL (talk) 10:36, 6 December 2008 (UTC)
- I'm not really familiar with larger turboprops, honestly. I know the Pratt & Whitney Canada PW100 has a two-stage centrifugal compressor, and it's at least 2000hp. I do think in general the centrifugal compressor is used in smaller engines. I know the article needs refs, but they're actually surprisingly hard to find. I've tried to include references from some of my A&P textbooks in the aircraft articles, but that's kind of hard to do since the books talk about specifics, while Wiki articles speak in generalities... i.e. "most common", "generally"... Someday I'll get around to fixing some of these articles. Shreditor (talk) 21:42, 6 December 2008 (UTC)
The article is about Turboprop's, a type of aircraft engine. The writing on it is well done, with a proper impartial disposition. The history section of the article seems to be well thought out. The visual aids that were chosen to accompany the article were of various types from various time periods which could be of use, although they did lack modern examples of the engine. They article appears to have little to no speculation done by the authors of this Wikipedia article. The major flaw in this article is its sources. While in the history section there are eight cited sources, five of the sources are from the same book which was published in 1955, another in 1971, and two from a book published in 2006, which presents a problem the more recent history of development, as there have been major changes to aviation since 1955, and any revision should include more recent publications to supplement the existing articles. --HIST406-10tmadrinan (talk) 05:22, 4 October 2010 (UTC)
Please explain to me how "Electra technology," for an airplane that didn't make its first flight until 1957, was used in the C-130, an airplane that was first conceived in 1950 and made its first flight in 1954? 18.104.22.168 (talk) 22:54, 28 August 2011 (UTC)
Turboprop market information
I would like to see relative market information about turboprops. Are there historical production estimates for turboprops? How does this compare to the other turbine-based engines used in the aircraft industry? What are the trends for future aircraft using turboprops? For example, does better TP bsfc equal a greater market share of TP engines over turbojets or turbofans? — Preceding unsigned comment added by 22.214.171.124 (talk) 18:35, 23 February 2013 (UTC)
Name too short
too slow to be turbo
A reduction gear makes the propeller spin slower, so a turboprop aircraft does not really have a "turbo" prop, in that the prop is less "turbo" than a direct-drive propeller. I think that should be noted in the article. Thanks. — Preceding unsigned comment added by 126.96.36.199 (talk) 02:58, 6 August 2013 (UTC)
- "Turbo" denotes powered by a turbine, hence turbojet, turbocharger, turboprop. In all these cases rotational power is extracted from the spinning turbine situated in the exhaust.
- In a simple turboprop the compressor and propeller are connected to the same shaft, both driven by the turbine. An example of the simple turboprop would be the Rolls-Royce Dart. In a 'free turbine' two separate concentric shafts are used, one driving the compressor, the other driving the propeller, each having separate turbines within the exhaust. An example of a 'free turbine' would be the Bristol Proteus. A 'two spool' design uses a similar concept to the free turbine but both turbines drive the compressor, while only one drives the propeller. An example of a two spool engine is the Rolls-Royce Tyne. — Preceding unsigned comment added by 188.8.131.52 (talk) 11:49, 25 October 2013 (UTC)
In the table (and Introduction) the Progress D-27 engine is listed. This seems to be despite the first entry that Propfans should not be confused with Turboprops. The entry for the Progress D-27 (and its page on the Progress website) define it as a Propfan. — Preceding unsigned comment added by 184.108.40.206 (talk) 05:29, 20 November 2013 (UTC)
1:1 Reduction Gear
would it not be a good idea to have here quantifications of the thrust delivered by the listed turboprop-engines (and also in all the linked special articles)? this is of relevance for everybody who thinks about vtol-airplanes wanting to know how much weight (downward force of a mass in the earth's gravitational field) a specific engine could neutralize or lift. to mathematically transform power (W = force times speed) in thrust (= force in N or hp, equivalent to the force of a mass in the earth's gravitation, i.e. 1 kg roughly equivalent of 10 N downward force) we would need the speed at which the power was delivered... the table lists the power-values as "take-off ratings", i.e. the thrust delivered at take-off-speed, no? but what were the different take-off-speeds? if my thinking is erroneous (I'm not a proper engineer...) please correct me and help, particularly with figures regarding the thrust of the Kuznetsov NK-12 at practically zero speed (imagining it lifting off a weight from the ground on a vtol-airvehicle, and with power equals zero since speed initially is practically zero...)?! thanx! --HilmarHansWerner (talk) 06:20, 2 January 2016 (UTC)
temperature of the exhaust gas stream?
does anybody have an idea about the temperature of the exhaust-gas-stream of a turboprop-engine, a) directly at the exhaust tube and then b) in the combined off-stream (propeller-stream mixed with hot exhaust-fumes) at different distances? that would be interesting to know in order to estimate how heat-resistant airplane-parts placed in the off-stream would have to be... (for instance the leading edge of a wing in a distance x from the exhaust-tube of the engine...) thanx! --HilmarHansWerner (talk) 06:27, 2 January 2016 (UTC)