Max Q
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Why are turboprops so named ?

Sat Oct 26, 2019 7:32 am

Always thought this was a poor and inaccurate way to categorize these aircraft


Many people assume this is a description of a ‘turbocharged propeller’ aircraft and why wouldn’t they ? the title is very misleading, propellers mean piston engines to most people and passengers


Hollywood doesn’t help, how many times have you seen a King Air start up with an accompanying piston engine sound effect ?!


Refueling personnel are often confused, thinking it has props so it must use Avgas although this is a survivable mistake unlike putting jet fuel in a piston aircraft which may not be



Finally it sells the aircraft short, I think the name ‘turboprop’ should be retired and replaced with ‘jet prop’ or ‘prop jet’


That is an accurate description of the power plant, a jet turbine driving a propeller through a reduction gearbox



I think passengers would be more receptive to flying on aircraft so named as well



Turboprop is a poor name, time for it to go
The best contribution to safety is a competent Pilot.
 
slcguy
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Re: Why are turboprops so named ?

Sat Oct 26, 2019 10:41 am

Don't think the name turboprop is the problem, people will always differentiate between props and jets regardless of the type of engine. As for trying a new way of naming them, it's been done. I remember flying on Frontier Convair 580s over 50 years ago with the words Jet Powered boldly painted on the sides of the plane! As for jet prop and prop jet, seem to remember those terms from way back in the day as well with various carriers. As for Hollywood and the media, there's no hope of them ever getting anything right when it comes to aviation!
 
slcguy
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Re: Why are turboprops so named ?

Sat Oct 26, 2019 12:12 pm

Here is an example from 1959 of an Eastern Lockheed (Prop-Jet) Electra.



An example of the previously mentioned Frontier Convair (Jet powered) 580 in 1964, look just ahead of the boarding door.



This trend didn't last long, people still saw propellers spinning out on the wings even if the airlines put the word jet on the planes. If using other terms didn't work then, doubt they will now.
 
AIRWALK
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Re: Why are turboprops so named ?

Sat Oct 26, 2019 2:39 pm

The turbo is short for turbomachinery which is a category of machines that transfer energy between a rotor and a fluid. So technically it makes sense, but it does make most think of turbochargers first
I'm sure this thread will take off soon
 
VSMUT
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Re: Why are turboprops so named ?

Sat Oct 26, 2019 4:28 pm

Turbine powered propeller, turbine-propeller, turboprop. I don't see the issue at all.

Jet is incorrect, there is no meaningful jet of air coming out of a turboprop. The thing a jet (turbojet and turbofan) have in common with the turboprop is the turbine, not the jet.
 
VSMUT
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Re: Why are turboprops so named ?

Sat Oct 26, 2019 4:33 pm

If anything, it should be called a geared turbofan. Because thats the closest you will get to describing it without the use of "prop". Alas, that name is already taken.
 
GalaxyFlyer
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Re: Why are turboprops so named ?

Sat Oct 26, 2019 4:52 pm

I can’t believe someone who I believe is a pilot started this thread. It’s been officially turbopropeller for 60+ years.
 
atomicstar
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Re: Why are turboprops so named ?

Sat Oct 26, 2019 5:02 pm

I don’t see a problem in the name. “turboprop” is short for “turbine-propeller”. It is driven by a turbine engine and thrust comes from the propeller.

I’m pretty sure that refueling personnel should know what type of fuel most aircraft uses. Most piston aircraft uses avgas, most turboprops and jets use jet-a.

And “jet” is not a good term because the turbine in a turboprop produces little thrust (in the same concept as how a APU also barely produces thrust). In turbofan engines, the turbine produces a significant amount of total thrust.
 
VSMUT
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Re: Why are turboprops so named ?

Sat Oct 26, 2019 5:06 pm

atomicstar wrote:
thrust comes from the propeller.


*Power ;)
 
426Shadow
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Re: Why are turboprops so named ?

Sat Oct 26, 2019 8:46 pm

GalaxyFlyer wrote:
I can’t believe someone who I believe is a pilot started this thread. It’s been officially turbopropeller for 60+ years.


Well respectfully, pilots just fly them, that doesn't mean they know more about them then say a mechanic or engineer.
We are all just fanboys, our opinions don't make or break businesses.
 
spacecadet
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Re: Why are turboprops so named ?

Sat Oct 26, 2019 9:03 pm

426Shadow wrote:
Well respectfully, pilots just fly them, that doesn't mean they know more about them then say a mechanic or engineer.


Pilots are required to know every part of every system on the planes they're certified to fly. That is part of the type rating process. Prior to being type rated on a particular airplane, they would have learned general systems for all or other airplanes. You literally can't become a pilot without that knowledge; it is what every test and checkride is about.
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426Shadow
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Re: Why are turboprops so named ?

Sat Oct 26, 2019 11:10 pm

spacecadet wrote:
426Shadow wrote:
Well respectfully, pilots just fly them, that doesn't mean they know more about them then say a mechanic or engineer.


Pilots are required to know every part of every system on the planes they're certified to fly. That is part of the type rating process. Prior to being type rated on a particular airplane, they would have learned general systems for all or other airplanes. You literally can't become a pilot without that knowledge; it is what every test and checkride is about.


That's not what I mean and of course I am aware of that. But the pilots didn't know a damn thing about MCAS either but they were still able to fly the plane.

The pilots know the operation of the system and the abnormal conditions as supplied by the manuals. Those manuals do NOT go into the kind of detail that the maintenance manuals or engineering documents do.
And to take it a step further, a typical pilot does not have the kind of knowledge about the turbo machinery as would the engineers at GE, PW and RR nor the knowledge of the aerodynamics as would an aerodynamicist.

I can't tell you how many times i've heard pilots on Youtube that are type rated say highly inaccurate things about the workings of their airplane but I wouldn't expect them to know everything.
We are all just fanboys, our opinions don't make or break businesses.
 
GalaxyFlyer
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 1:15 am

And they call themselves “pros”. We jusT don’t teach basics anymore. Heck, the written exams are out of a question bank, no education required.

GF
 
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SierraPacific
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 3:38 am

GalaxyFlyer wrote:
And they call themselves “pros”. We jusT don’t teach basics anymore. Heck, the written exams are out of a question bank, no education required.

GF


I am completely ignorant of how it was done previously since that was well before my time but wasn't the written exam always a sort of formality before the real oral exam and flight portion (where you prove you know it)? They recently stopped releasing the test bank to prevent/limit the rote memorization even though there is quite a selection of services that help prepare for the written exam.

I know plenty of young guys (including myself) that try our absolute best to be as knowledgable as we can when it comes to knowledge of our aircraft.
 
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Starlionblue
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 7:05 am

Drifting off topic here a bit, but...


SierraPacific wrote:
GalaxyFlyer wrote:
And they call themselves “pros”. We jusT don’t teach basics anymore. Heck, the written exams are out of a question bank, no education required.

GF


I am completely ignorant of how it was done previously since that was well before my time but wasn't the written exam always a sort of formality before the real oral exam and flight portion (where you prove you know it)? They recently stopped releasing the test bank to prevent/limit the rote memorization even though there is quite a selection of services that help prepare for the written exam.

I know plenty of young guys (including myself) that try our absolute best to be as knowledgable as we can when it comes to knowledge of our aircraft.


This seems to me a North American thing, with a relatively simple written exam, and just one exam. In EASA, Australia, South Africa and other places, the fourteen-ish CPL/ATPL exams take at least 6 months of full-time study to prepare for, including proper ground school.


GalaxyFlyer wrote:
And they call themselves “pros”. We jusT don’t teach basics anymore. Heck, the written exams are out of a question bank, no education required.

GF


AFAIK in EASA this has changed in the past few years. Purely knowing the answers is not enough. For that matter, it was never enough for exams such as General Navigation. If you didn't know how to do the maths, you'd fail.

spacecadet wrote:
426Shadow wrote:
Well respectfully, pilots just fly them, that doesn't mean they know more about them then say a mechanic or engineer.


Pilots are required to know every part of every system on the planes they're certified to fly. That is part of the type rating process. Prior to being type rated on a particular airplane, they would have learned general systems for all or other airplanes. You literally can't become a pilot without that knowledge; it is what every test and checkride is about.


While it is true that we have comprehensive knowledge of the aircraft that we are rated on, we are not really required to know "every part of every system". We are required to know, and well, the relevant parts of the systems that are relevant to us as pilots. The stuff that is in the pilot manuals.

Do I know which hydraulic system runs the flaps, and which the slats? Sure, but that might be quite good working knowledge in the case of a hydraulic failure, even though I can easily look it up the QRH. Can I recall from memory which hydraulic system runs spoiler 3 on the left wing? No, but I can look it up. Do I know where the hydraulic lines are physically located? It is not even in my manuals.

For that matter, there are plenty of systems onboard that I know little about. I know that power to the galleys can be turned off with a pushbutton in the overhead, but I don't know the details of the ovens or coffee makers. And I don't know very much about the toilet flushing system beyond the fact that it works with pressure.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Max Q
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 9:23 am

slcguy wrote:
Here is an example from 1959 of an Eastern Lockheed (Prop-Jet) Electra.



An example of the previously mentioned Frontier Convair (Jet powered) 580 in 1964, look just ahead of the boarding door.



This trend didn't last long, people still saw propellers spinning out on the wings even if the airlines put the word jet on the planes. If using other terms didn't work then, doubt they will now.



Exactly, in that era airline management realized the value in highlighting that these new aircraft may have propellers but they were turbine powered


In other words this is ‘not your dad’s DC 7’


Whoever dreamed up the term ‘turboprop’ did these manufacturers a disservice
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Starlionblue
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 10:35 am

Max Q wrote:
slcguy wrote:
Here is an example from 1959 of an Eastern Lockheed (Prop-Jet) Electra.



An example of the previously mentioned Frontier Convair (Jet powered) 580 in 1964, look just ahead of the boarding door.



This trend didn't last long, people still saw propellers spinning out on the wings even if the airlines put the word jet on the planes. If using other terms didn't work then, doubt they will now.



Exactly, in that era airline management realized the value in highlighting that these new aircraft may have propellers but they were turbine powered


In other words this is ‘not your dad’s DC 7’


Whoever dreamed up the term ‘turboprop’ did these manufacturers a disservice


I don't know if it goes that deep. Certainly many people will see a pair of propellers and think the plane is "old" even though it is a brand new state of the art turboprop with FADEC and EFIS up the kazoo. The turboprop nomenclature is in most cases completely unknown to them. Perhaps apart from the fact that there is a "prop" in there somewhere.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
citationjet
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 3:01 pm

Max Q wrote:
Always thought this was a poor and inaccurate way to categorize these aircraft
the title is very misleading, propellers mean piston engines to most people and passengers
Finally it sells the aircraft short, I think the name ‘turboprop’ should be retired and replaced with ‘jet prop’ or ‘prop jet’
I think passengers would be more receptive to flying on aircraft so named as well
Turboprop is a poor name, time for it to go

[extraneous blank lines removed from OP's initial post]

I don't believe that changing the name from 'turboprop' to either 'jet prop' or 'prop jet' will do anything to change the public's perception of these aircraft.
The issue with public perception is the visual image of the propeller and the term "prop". The name change you propose still uses the term 'prop'.
Regardless of what they are called, the general public will still view these propeller aircraft as a noisy, slow flying, low flying, and vibrating experience.
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kalvado
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 3:13 pm

More like the word "jet" is abused. Somewhat fair for 707, by now high bypass turbofan engines have only minor jet component.
Turbofan vs turboprop is more fair wording, reflecting actual differences: turbine driven fan vs turbine driven prop.
 
GalaxyFlyer
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 3:16 pm

SierraPacific wrote:
GalaxyFlyer wrote:
And they call themselves “pros”. We jusT don’t teach basics anymore. Heck, the written exams are out of a question bank, no education required.

GF


I am completely ignorant of how it was done previously since that was well before my time but wasn't the written exam always a sort of formality before the real oral exam and flight portion (where you prove you know it)? They recently stopped releasing the test bank to prevent/limit the rote memorization even though there is quite a selection of services that help prepare for the written exam.

I know plenty of young guys (including myself) that try our absolute best to be as knowledgable as we can when it comes to knowledge of our aircraft.


The FAA tests at one time were very closely held secrets—only the subject matter was released. So, you needed to study and master W&B, navigation, the FARs and how to apply them to a situation. The secret question bank was changed regularly whenever the FAA thought the grades were too high. There were many schools that taught the material, had students take the tests and then screened them for the questions to “improve” the classes. Then, FOIA Law passes, the schools demanded the FAA open up the question banks. That’s how we got here. Today, it’s just a formality to take the tests and, IMO, much too much theory is not presented or tested. Performance is especially done hard by. Is out we our weight less than nnnn.n; we’re good to go. That’s my experience.
 
DALMD80
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 3:19 pm

Max Q wrote:
Always thought this was a poor and inaccurate way to categorize these aircraft


Many people assume this is a description of a ‘turbocharged propeller’ aircraft and why wouldn’t they ? the title is very misleading, propellers mean piston engines to most people and passengers


Hollywood doesn’t help, how many times have you seen a King Air start up with an accompanying piston engine sound effect ?!


Refueling personnel are often confused, thinking it has props so it must use Avgas although this is a survivable mistake unlike putting jet fuel in a piston aircraft which may not be



Finally it sells the aircraft short, I think the name ‘turboprop’ should be retired and replaced with ‘jet prop’ or ‘prop jet’


That is an accurate description of the power plant, a jet turbine driving a propeller through a reduction gearbox



I think passengers would be more receptive to flying on aircraft so named as well



Turboprop is a poor name, time for it to go

Turbine-propeller. Most pax don't care, it flies. "It'll take off, it'll land, yay. I don't care what it is if I get there."
2 wrongs don't make a right, but 2 Wrights made an airplane, and look at the miracles we have today!
 
DALMD80
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 3:20 pm

Starlionblue wrote:
Max Q wrote:
slcguy wrote:
Here is an example from 1959 of an Eastern Lockheed (Prop-Jet) Electra.



An example of the previously mentioned Frontier Convair (Jet powered) 580 in 1964, look just ahead of the boarding door.



This trend didn't last long, people still saw propellers spinning out on the wings even if the airlines put the word jet on the planes. If using other terms didn't work then, doubt they will now.



Exactly, in that era airline management realized the value in highlighting that these new aircraft may have propellers but they were turbine powered


In other words this is ‘not your dad’s DC 7’


Whoever dreamed up the term ‘turboprop’ did these manufacturers a disservice


I don't know if it goes that deep. Certainly many people will see a pair of propellers and think the plane is "old" even though it is a brand new state of the art turboprop with FADEC and EFIS up the kazoo. The turboprop nomenclature is in most cases completely unknown to them. Perhaps apart from the fact that there is a "prop" in there somewhere.

Agreed. I think people even think that props aren't as safe as jets. Not true at all.
2 wrongs don't make a right, but 2 Wrights made an airplane, and look at the miracles we have today!
 
VSMUT
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 3:56 pm

Rebranding is not the way forward to improve passenger perception of propellers. That's just nonsense. People are afraid of the propellers when they see them during boarding, not the tiny little "AT72" or "Q400" moniker listed during the booking process.

You would be far better off by showing the passengers that they really aren't old WWII era planes that are bound to crash at any moment. I'm thinking something like writing the year of manufacture next to the boarding door and on the safety cards. My own experience is that most of the passengers that complain see a brand new ATR pull up, and they would much rather be on a 30 year old 737 classic, because "jets are newer".
 
PerVG
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 7:07 pm

What should we call turbojets and turbofans, then?
 
GalaxyFlyer
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Re: Why are turboprops so named ?

Sun Oct 27, 2019 7:23 pm

Outside the pedantic world of A.net, its a jet IF doesn’t have propellers. My F/E certificate says “turbojet powered “.
 
Max Q
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Re: Why are turboprops so named ?

Mon Oct 28, 2019 9:20 am

GalaxyFlyer wrote:
Outside the pedantic world of A.net, its a jet IF doesn’t have propellers. My F/E certificate says “turbojet powered “.



So does mine and you just made my point
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flipdewaf
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Re: Why are turboprops so named ?

Mon Oct 28, 2019 10:33 am

VSMUT wrote:
atomicstar wrote:
thrust comes from the propeller.


*Power ;)

Power is delivered to a propeller in the form of torque and rotational speed. The propeller creates thrust by delivering power to the air i.e. rate of change of kinetic energy, the two are intrinsically linked.

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kurtverbose
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Re: Why are turboprops so named ?

Mon Oct 28, 2019 12:52 pm

Are we also renaming 'turboshaft' to jetshaft or shaftjet?

Actually, if we're renaming all the turbo instances with jet, for the sake of consistency, we get jetjet instead of turbojet, jetfan instead of turbofan, jetshaft instead of turboshaft. Doesn't really work!

When all these names came out (1940's to 1960's) the name turbocharger wasn't really used by the general public or by the aviation community. Internal combustion engines which were turbocharged were called supercharged - with the compressor driven by an exhaust driven turbine (quite a mouthful). This might be just from a British point of view, but that's the nomenclature I read in contemporary books - e.g. by Stanley Hooker. I think the early American nomenclature was turbo-supercharged. In any case the turbo bit refers to what it does directly to the engine, not what it does indirectly to the propeller. You can't get a turbocharged propeller.

As for the ignorance of the traveling public, they just know props are slow and noisy and jets are fast and quiet. Apart from trips over short distances, both these things are true. I can't see how a re-naming would help here?

Incidentally, given the huge number of 150-200 seat regional aircraft, it's been debated here whether the market would fragment and there would be room for a 150 seat 'jetprop' to cover shorter ranges more economically. It's a shame it hasn't happened, but I don't think it's because of the name 'turboprop', I think it's because of the name 'prop' - and a log of economic/industrial/political issues. I think, certainly in Europe, user acceptance would be easy to overcome if the 'jetprop' had a lower ticket price.
 
kalvado
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Re: Why are turboprops so named ?

Mon Oct 28, 2019 1:17 pm

kurtverbose wrote:
You can't get a turbocharged propeller.

A matter of naming convention.
You can consider any turbine engine to be turbocharged - there is a turbine driven by exhaust gas, which compresses incoming air.
If my memory serves me right, there were piston planes where another piston engine was driving compressor to "piston-charge" engines. In theory, there is nothing wrong with using turbine - driven by whatever power source available for pre-compression. Actually, https://en.wikipedia.org/wiki/Pratt_%26 ... Wasp_Major

So, there are 3 naming components to be considered.
Thrust producing mechanism - prop, fan, jet. Boundaries are somewhat unclear with unducted fan and bypass ratios.
Combustion utilization - piston, turbine drive
pre-compression - none, turbine directly driven, external (multiple drive options), ram air,
If using al three, turbo-turbo-prop and turbo-turbo-fanjet would be proper naming for todays birds. Centri-piston-prop would describe B-36 :hyper:
 
DALMD80
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Re: Why are turboprops so named ?

Mon Oct 28, 2019 4:52 pm

VSMUT wrote:
Rebranding is not the way forward to improve passenger perception of propellers. That's just nonsense. People are afraid of the propellers when they see them during boarding, not the tiny little "AT72" or "Q400" moniker listed during the booking process.

You would be far better off by showing the passengers that they really aren't old WWII era planes that are bound to crash at any moment. I'm thinking something like writing the year of manufacture next to the boarding door and on the safety cards. My own experience is that most of the passengers that complain see a brand new ATR pull up, and they would much rather be on a 30 year old 737 classic, because "jets are newer".

I hate the "stereotype" that turboprops and props in general are more dangerous.
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dennypayne
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Re: Why are turboprops so named ?

Mon Oct 28, 2019 6:21 pm

I really don't think it matters to the general public whether a 'propeller plane' is powered by a piston engine, a jet turbine, or magic fairy dust. I think they do equate propellers with less safety - after all, most general aviation aircraft are propeller-driven, and GA does have a higher rate of accidents. So I don't think it's necessarily a falsehood to say that 'prop planes are less safe.' We may all know that Part 121 ops are a different beast, but most people don't have that knowledge.

I've even seen check-box options on corporate travel sites for 'Avoid Propeller Aircraft.' So to the original premise of the post, I doubt renaming turboprops will accomplish much, as long as there is a market for the 'prop plane' stereotype. It's a shame though - I just flew on an F50 for the first time and I'd take that any day over a CRJ-200.

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SAAFNAV
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Re: Why are turboprops so named ?

Tue Oct 29, 2019 12:54 pm

Starlionblue wrote:
This seems to me a North American thing, with a relatively simple written exam, and just one exam. In EASA, Australia, South Africa and other places, the fourteen-ish CPL/ATPL exams take at least 6 months of full-time study to prepare for, including proper ground school.


Having just written the South African ATP syllabus, I'm not entirely sure it makes you better at anything.
It is incredibly vague, and at the same time incredibly specific. Flight Planning specifically borders on building an aircraft by certification standards, but practically, the exam is of no use in the real world.

Sure, you can work out integrated range tables up the ying yang, but nowhere do they test you in your ability to think through an entire flight's planning.

I'd rather prefer a generic FAA-type test coupled with a thorough oral exam probing your understanding than wasting months on Questionbanks and groundschool, but still have no idea.

I have loads and loads of examples from the actual exams that are so type-specific, yet only our wonderful CAA knows the right answer.
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SheikhDjibouti
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Re: Why are turboprops so named ?

Tue Oct 29, 2019 3:57 pm

citationjet wrote:
'.
Regardless of what they are called, the general public will still view these propeller aircraft as a noisy, slow flying, low flying, and vibrating experience.

Why?
How many of "the general public" have any actual experience of propeller driven aircraft these days? Many of them have only ever flown by jet. Or in a Cessna 172.

They might possibly figure that propeller = slower, but why would they add the other criticisms?

Noisy? When would they have come across anything bigger (& noisier) than a Cessna 402?
Low flying? Wouldn't most people figure simply that GA fly low, airliners fly higher.
Vibrating? Even those with a degree in mechanical engineering might assume that if their car runs nice & smooth with a 6-cylinder engine instead a 4-pot, then a big old aircraft engine with 32-cylinders must be like surfing on whipped cream. The fact that reciprocating engines are simply no longer used on airliners is not even part of their equation. So why assume vibration is an issue that they consider?

It is true that yo' grandfather might be able to tell you what it was like to ride in a DC-6 or L-1049, but apart from that the public knows nothing.

Nevertheless, I can believe that many have a bias against propellers, without them actually being able to explain why. Perhaps it is simply fear of the unknown? :roll:
Nothing to see here; move along please.
 
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SheikhDjibouti
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Re: Why are turboprops so named ?

Tue Oct 29, 2019 5:27 pm

kurtverbose wrote:
When all these names came out (1940's to 1960's) the name turbocharger wasn't really used by the general public or by the aviation community. Internal combustion engines which were turbocharged were called supercharged - with the compressor driven by an exhaust driven turbine (quite a mouthful). This might be just from a British point of view, but that's the nomenclature I read in contemporary books - e.g. by Stanley Hooker. I think the early American nomenclature was turbo-supercharged.
Like you, I wasn't there, and whilst I would like to believe everybody here on a.net knows the difference, my understanding is that a supercharger uses a mechanical drive from the engine (or sometimes from a secondary engine), whereas a turbocharger utilises "free" energy from exhaust gases to drive a turbine that in turn allows you to drive a compressor.

Historically it was superchargers that were more commonly known to the general public, in the UK thanks partly to the Bentley Boys and their efforts at Le Mans with their Bentley Blower No.1 ("Blower" being a crude description of a supercharger)

As to Stanley Hooker's contribution, the Rolls Royce (& Packard) Merlin engines were always known as supercharged, because that is exactly what they were - i.e. a compressor driven by a mechanical linkage. The two-stage supercharger on later models of the Spitfire absorbed something like 250hp directly from the engine crankshaft, which I find staggering. Even better, I recall that the supercharged Merlin would only deliver an extra 250hp at low level, meaning that it was a zero-sum equation. :o The real benefit only came into play at higher altitudes....
(no, I cannot find that reference at this point in time - sorry)

It was the Swiss (Sulzer) who initially made advances with turbochargers, on diesel engines fitted to ships, and subsequently diesel locomotive engines.
Later on, around the same time as Rolls Royce were refining the supercharged Merlin engine, the USAAC were concentrating on turbo-superchargers for high altitude boost, believing that further development of turbo-superchargers would allow their engines to outperform European rivals using displacement superchargers.

May I recommend the wikipedia article on the Allison V-1710? This engine started out with a single stage supercharger, but was also developed with a turbocharger (or turbo-supercharger in the nomenclature of the day). The full story is quite convoluted, and takes us further off-topic, so help yourself.

https://en.wikipedia.org/wiki/Allison_V ... percharger

As for the ignorance of the traveling public, they just know props are slow and noisy and jets are fast and quiet. Apart from trips over short distances, both these things are true.
Ouch! I'm not 100% sure I agree with the noisy/quiet part.
And you will have to define "short distances" in terms of whether you are addressing a European, an American, or in the worst case, an Australian. :lol:
Nothing to see here; move along please.
 
citationjet
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Re: Why are turboprops so named ?

Tue Oct 29, 2019 9:17 pm

SheikhDjibouti wrote:
How many of "the general public" have any actual experience of propeller driven aircraft these days? Many of them have only ever flown by jet. Or in a Cessna 172. They might possibly figure that propeller = slower, but why would they add the other criticisms? Noisy? When would they have come across anything bigger (& noisier) than a Cessna 402?

In the 1980s my wife worked for American Airlines on ticket counter and gate. In the late 80s AA dropped all jet service (727-200s) in ICT, and replaced it with Saab 340s, and ATR 72s. The customers did not like the change. They did not like the longer flight times, flying thru turbulence rather than above it, and the lack of First Class seats, among their complaints. AA lost many customers to other airlines out of our city. There were articles written in the local paper complaining about the prop service, and we are talking about Wichita, KS, the Air Capital of the World. The customer count went back up after the jets were reinstated.

SheikhDjibouti wrote:
Low flying? Wouldn't most people figure simply that GA fly low, airliners fly higher.

I just checked flightaware for current cruise altitudes of various turboprops (ATR72, Dash 8, and Q400) today. The highest cruise altitudes I could find were less than 20,000 ft. The smallest commuter jets (ie CRJ-200) typically fly about 32,000 ft.

SheikhDjibouti wrote:
Vibrating? Even those with a degree in mechanical engineering might assume that if their car runs nice & smooth with a 6-cylinder engine instead a 4-pot, then a big old aircraft engine with 32-cylinders must be like surfing on whipped cream. The fact that reciprocating engines are simply no longer used on airliners is not even part of their equation. So why assume vibration is an issue that they consider?

I have a degree in mechanical engineering, and retired from Cessna Aircraft as Executive Engineer. The issue is not the engine itself, it is the shock waves coming off the tips of the propellers that generate the vibration in the structure.

SheikhDjibouti wrote:
Nevertheless, I can believe that many have a bias against propellers, without them actually being able to explain why. Perhaps it is simply fear of the unknown? :roll:

For the customer, perception is reality.

Here is a LA Times newspaper article from 1993, about the time that AA went to turboprops.
https://www.latimes.com/archives/la-xpm-1993-03-12-fi-10120-story.html
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SheikhDjibouti
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Re: Why are turboprops so named ?

Tue Oct 29, 2019 11:33 pm

SheikhDjibouti wrote:
How many of "the general public" have any actual experience of propeller driven aircraft these days? Many of them have only ever flown by jet. Or in a Cessna 172. They might possibly figure that propeller = slower, but why would they add the other criticisms? When would they have come across anything bigger (& noisier) than a Cessna 402?

citationjet wrote:
I have a degree in mechanical engineering, and retired from Cessna Aircraft as Executive Engineer.
Pleased to meet you; I regret my own c.v. is far less impressive so I don't doubt you have more knowledge on this subject than myself.
But my point was more about what "the general public" actually knows about the differences, or whether their actions are simply blind prejudice.

In the late 80s AA dropped all jet service (727-200s) in ICT, and replaced it with Saab 340s, and ATR 72s. The customers did not like the change.
An all too familiar story. Thirty years ago the memories of reciprocating engine airliners were still fresh enough to be an issue for some, even though the Saab & ATR replacements were totally different state-of-the-art turboprops.

I just checked flightaware for current cruise altitudes of various turboprops (ATR72, Dash 8, and Q400) today. The highest cruise altitudes I could find were less than 20,000 ft. The smallest commuter jets (ie CRJ-200) typically fly about 32,000 ft.
Strange - on FR24 I can find Dash8s cruising at FL240, and occasionally bumped up to FL250 (the service ceiling for most in this class). I don't necessarily see this as a big difference, but I simply cannot allow your data to stand unchallenged. Sorry!
IIRC one of the particular selling points of the Do328 was it's ability to cruise in the "empty space" at around 30,000', higher than most other turboprops, and below most RJs.

What is most telling from FR24 today is that earlier today, whilst there were 40+ ATR-72s in the air over Europe, another 110+ over Asia, 30+ over Australia & NZ, and 35 over Central and South America, when it came to North America, there were NONE! That pretty much tells you all you need to know. :roll:

I wrote:
Vibrating? Even those with a degree in mechanical engineering might assume that if their car runs nice & smooth with a 6-cylinder engine instead a 4-pot, then a big old aircraft engine with 32-cylinders must be like surfing on whipped cream. The fact that reciprocating engines are simply no longer used on airliners is not even part of their equation. So why assume vibration is an issue that they consider?

you wrote:
I have a degree in mechanical engineering, and ….
The issue is not the engine itself, it is the shock waves coming off the tips of the propellers that generate the vibration in the structure.

You know that, and I know that, and maybe so do a fair number of others here on a.net. (then again, I may be far too generous)
But would an ordinary (non-aviation) mechanical engineer know this? :shakehead:
Plus, are the shock waves from modern six-blade props striking a modern composite fuselage and high-aspect wing going to cause the same levels of distress as with a DC-6?
I have never flown a DC-6, but the last time I flew in a Dash8 I didn't find it noticeably unpleasant.

I wrote:
Nevertheless, I can believe that many have a bias against propellers, without them actually being able to explain why.
you wrote:
For the customer, perception is reality.

On this we can agree. And it makes me sad.
Nothing to see here; move along please.
 
Nicoeddf
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Re: Why are turboprops so named ?

Wed Oct 30, 2019 6:43 am

spacecadet wrote:
426Shadow wrote:
Well respectfully, pilots just fly them, that doesn't mean they know more about them then say a mechanic or engineer.


Pilots are required to know every part of every system on the planes they're certified to fly. That is part of the type rating process. Prior to being type rated on a particular airplane, they would have learned general systems for all or other airplanes. You literally can't become a pilot without that knowledge; it is what every test and checkride is about.


Not. At. All.

What gives you that strange idea? It can be argued it would even be detrimental to have such in depth knowledge as crews might want to find their own solutions rather than use approved procedure.
Pilots are expected to handle the plane according to procedures built by the OEM. That doesn't require to know every part of every system, but a good overview of functionality and interdependencies.

Every test ride and every check is explicitly NOT about every part of every system, but about their design in functionality inflight, failure modes and consequences of multiple system failures.
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citationjet
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Re: Why are turboprops so named ?

Wed Oct 30, 2019 4:15 pm

SheikhDjibouti wrote:
What is most telling from FR24 today is that earlier today, whilst there were 40+ ATR-72s in the air over Europe, another 110+ over Asia, 30+ over Australia & NZ, and 35 over Central and South America, when it came to North America, there were NONE! That pretty much tells you all you need to know.

Of the 106 de Havilland Dash 8-400s currently flying, more than 60 of them are currently flying over the US and Canada.
https://flightaware.com/live/aircrafttype/DH8D
Boeing Flown: 701,702,703;717;720;721,722;731,732,733,734,735,737,738,739;741,742,743,744,747SP;752,753;762,763;772,773.
 
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SheikhDjibouti
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Re: Why are turboprops so named ?

Wed Oct 30, 2019 6:58 pm

citationjet wrote:
SheikhDjibouti wrote:
What is most telling from FR24 today is that earlier today, whilst there were 40+ ATR-72s in the air over Europe, another 110+ over Asia, 30+ over Australia & NZ, and 35 over Central and South America, when it came to North America, there were NONE! That pretty much tells you all you need to know.

Of the 106 de Havilland Dash 8-400s currently flying, more than 60 of them are currently flying over the US and Canada.

Do we really need to do this?
How many of those Dash-8-400s were flying somewhere North of the 49th parallel? The majority.
Of the ones flying over the USA, how many were Canadian registered and flying to/from a Canadian airport? The majority (e.g. Westjet & Porter, serving destinations in New England)
Of the US registered examples (barely a dozen), how many were Alaska Horizon, and out of Seattle or Portland, two cities adjacent the Canadian border? All of them. (¹)

Are you seeing a connection yet?

I apologize for picking the ATR-72; I assumed it would be a reasonable choice, unlike say the Ilyushin Il-114. TBH the result surprised me too.
But the numbers for the Dash-8-Q400 are really not much better once you examine them properly.

(¹) Ok, I admit Portland is a bit of a stretch, but it's a lot closer to Vancouver than it is to SFO or LAX
(²) In my earlier analysis, I adjusted the time frame to include peak periods all around the globe (& stated that clearly); whereas your "106" snapshot has shut out Asia, Australia, and half of Europe. With a little more effort you could have arranged it for 17:00hrs in Seattle (midnight in Berlin), and claim zero Dash-8s flying in Europe. :duck:
Nothing to see here; move along please.
 
nmcalba
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Re: Why are turboprops so named ?

Wed Oct 30, 2019 8:27 pm

I had a quick search through the archives of Flight magazine to see when the term turbo-prop was first used.

The first reference I could find was from Dec 1946 - which talks about the "The Hadley Page Hermes with four Bristol Theseus turbo-props"

There were quite a few references to turboprops before that - dating back to 1944, but they were referred to as "Turbine/Airscrews" in contrast to "Turbine/Jets".

There is even a reference in a Feb 1945 article describing the various possibilities of jet engines of what we now call a turbo-fan - although there it was called a "Turbine with augmenter".

I was quite surprised to see the amount of detailed discussion going on about jet engines, given that this was being published in wartime.

Interestingly the Feb 45 article by Air Commodore Banks entitled "Turbines or piston engines" has the prescient comment by the Air Cmdr about jet engines: "It will, in my opinion, be so competitive in 5 or 10 years time that the large piston engine may not survive, and the smaller piston engine will have a hard time to exist also". It is quite odd however given, the sophistication of modern jet engines, to see one of the main advantages of jet engines being given as "the speed at which it can be evolved ....... even the more complex turbine types and those having airscrews should only take about half the time of the equivalent piston engine to develop"
 
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Starlionblue
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Re: Why are turboprops so named ?

Wed Oct 30, 2019 11:26 pm

nmcalba wrote:
I had a quick search through the archives of Flight magazine to see when the term turbo-prop was first used.

The first reference I could find was from Dec 1946 - which talks about the "The Hadley Page Hermes with four Bristol Theseus turbo-props"

There were quite a few references to turboprops before that - dating back to 1944, but they were referred to as "Turbine/Airscrews" in contrast to "Turbine/Jets".

There is even a reference in a Feb 1945 article describing the various possibilities of jet engines of what we now call a turbo-fan - although there it was called a "Turbine with augmenter".

I was quite surprised to see the amount of detailed discussion going on about jet engines, given that this was being published in wartime.

Interestingly the Feb 45 article by Air Commodore Banks entitled "Turbines or piston engines" has the prescient comment by the Air Cmdr about jet engines: "It will, in my opinion, be so competitive in 5 or 10 years time that the large piston engine may not survive, and the smaller piston engine will have a hard time to exist also". It is quite odd however given, the sophistication of modern jet engines, to see one of the main advantages of jet engines being given as "the speed at which it can be evolved ....... even the more complex turbine types and those having airscrews should only take about half the time of the equivalent piston engine to develop"


I don't think the development time comment is that surprising given the situation at the time. By the end of the war piston engines had been pushed to extremes. And unlike early jets, large aircraft pistons are difficult and costly to scale up, with ever added complexity. Large airliner piston engines had endemic reliability issues. One of the big advantages of switching to jets was reliability.

The conceptual simplicity of the jet engine concept must have seemed very scalable in comparison. This was also very early in jet engine development when there was plenty of low hanging fruit, whilst there was not that much more that could be extracted out of pistons.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
citationjet
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Re: Why are turboprops so named ?

Thu Oct 31, 2019 1:20 pm

There is a related thread that popped up yesterday in the Civil Aviation forum, It already has 50 replies.

Why are turboprops so unpopular in the US?
https://www.airliners.net/forum/viewtopic.php?f=3&t=1434053
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superbizzy73
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Re: Why are turboprops so named ?

Thu Oct 31, 2019 7:18 pm

To the original post...if you put AvGas in a turboprop (yep, staying with that name), then you’re fired...
 
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Starlionblue
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Re: Why are turboprops so named ?

Fri Nov 01, 2019 10:30 am

superbizzy73 wrote:
To the original post...if you put AvGas in a turboprop (yep, staying with that name), then you’re fired...


The King Air can do avgas. But there are conditions attached.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
kurtverbose
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Re: Why are turboprops so named ?

Mon Nov 04, 2019 12:01 pm

SheikhDjibouti wrote:
Like you, I wasn't there, and whilst I would like to believe everybody here on a.net knows the difference, my understanding is that a supercharger uses a mechanical drive from the engine (or sometimes from a secondary engine), whereas a turbocharger utilises "free" energy from exhaust gases to drive a turbine that in turn allows you to drive a compressor.


You don't need to be, all you have to do (as I stated) is read the contemporary documentation, which you seem not to have done. And yes, that is the modern definition, but as explained, it wasn't the initial one - they were both forms of supercharging - which by initial definition just means forced induction.

SheikhDjibouti wrote:
As to Stanley Hooker's contribution, the Rolls Royce (& Packard) Merlin engines were always known as supercharged, because that is exactly what they were - i.e. a compressor driven by a mechanical linkage. The two-stage supercharger on later models of the Spitfire absorbed something like 250hp directly from the engine crankshaft, which I find staggering. Even better, I recall that the supercharged Merlin would only deliver an extra 250hp at low level, meaning that it was a zero-sum equation. :o The real benefit only came into play at higher altitudes....
(no, I cannot find that reference at this point in time - sorry)


It's wouldn't be a zero sum equation because it was driven by a two speed gearbox. A pilot wouldn't have the supercharger running at full chat when the engine couldn't take the boost at low level.

SheikhDjibouti wrote:
Ouch! I'm not 100% sure I agree with the noisy/quiet part.
And you will have to define "short distances" in terms of whether you are addressing a European, an American, or in the worst case, an Australian. :lol:


You're correct. It's mainly perception. Maybe it's the pitch, but I notice them to be noisier. Empirical evidence suggest otherwise. As to what is a short distance - a mile is a mile, whether it's in Europe or America.
 
pickafivestring
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Re: Why are turboprops so named ?

Mon Nov 04, 2019 4:30 pm

VSMUT wrote:
Turbine powered propeller, turbine-propeller, turboprop. I don't see the issue at all.

Jet is incorrect, there is no meaningful jet of air coming out of a turboprop. The thing a jet (turbojet and turbofan) have in common with the turboprop is the turbine, not the jet.



Disagree. There is enough residual thrust from the exhaust, that the performance tables take it into account in the POH. At high speeds it can approach 10% in extreme cases, but is usually less.
 
VSMUT
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Re: Why are turboprops so named ?

Mon Nov 04, 2019 6:17 pm

pickafivestring wrote:
VSMUT wrote:
Turbine powered propeller, turbine-propeller, turboprop. I don't see the issue at all.

Jet is incorrect, there is no meaningful jet of air coming out of a turboprop. The thing a jet (turbojet and turbofan) have in common with the turboprop is the turbine, not the jet.



Disagree. There is enough residual thrust from the exhaust, that the performance tables take it into account in the POH. At high speeds it can approach 10% in extreme cases, but is usually less.


It is something like 50 kg of thrust on the ATR. Not even enough to get it rolling with brakes released.
 
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SheikhDjibouti
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Re: Why are turboprops so named ?

Mon Nov 04, 2019 7:36 pm

kurtverbose wrote:
...all you have to do (as I stated) is read the contemporary documentation, which you seem not to have done.
Excuse me?
SheikhDjibouti wrote:
Historically it was superchargers that were more commonly known to the general public...
….the Allison V-1710... started out with a single stage supercharger, but was also developed with a turbocharger (or turbo-supercharger in the nomenclature of the day)
So, many thanks for that slap around the face, but as I was agreeing with you I'm not sure what I did to deserve it. :white:

kurtverbose wrote:
And yes, that is the modern definition, but as explained, it wasn't the initial one - they were both forms of supercharging - which by initial definition just means forced induction.
Yes, I never had a problem with that.
kurtverbose wrote:
When all these names came out (1940's to 1960's) the name turbocharger wasn't really used by the general public or by the aviation community.

Correct. :checkmark: The use of "turbocharger" in those days was rare indeed. (didn't we agree on that already?)

However, it did appear in a recognisable form as turbosupercharger (or exhaust turbo-supercharger) as early as 1934. :o

As for today's more succinct "turbocharged", the earliest incarnation I can find is from 1963 with the introduction of the Continental TSIO-520 engine.
Could it be that Continental themselves adopted that terminology in their advertising, and the rest (as they say) is history?
But I haven't read every document on the planet, so if you can come up with something earlier, I'm ok with that too. :D
Nothing to see here; move along please.
 
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SheikhDjibouti
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Re: Why are turboprops so named ?

Mon Nov 04, 2019 7:52 pm

VSMUT wrote:
pickafivestring wrote:
VSMUT wrote:
Jet is incorrect, there is no meaningful jet of air coming out of a turboprop.

Disagree. There is enough residual thrust from the exhaust, that the performance tables take it into account in the POH. At high speeds it can approach 10% in extreme cases, but is usually less.

It is something like 50 kg of thrust on the ATR. Not even enough to get it rolling with brakes released.

Whilst I respect your expertise in many things relating to ATRs and Dash-8s, there were other turboprop powered airliners before them.

Wikipedia wrote:
Bristol Britannia; Bristol Proteus engine
Maximum power output: 3,320 shp (2,475 kW) + 1,200 lb (5.33 kN) residual thrust giving 3,780 eshp

That's 13.8% residual thrust.

Back when I was young, "eshp" was a recognised term, but it doesn't seem to feature so much these days. Maybe modern turboprop engines are so fabulously efficient it is negligible as you say. :scratchchin:

EDIT - I have found a figure for the PW150.... and I'll leave it there. :wave:
Nothing to see here; move along please.
 
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akiss20
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Re: Why are turboprops so named ?

Mon Nov 04, 2019 10:16 pm

SheikhDjibouti wrote:
VSMUT wrote:
pickafivestring wrote:
Disagree. There is enough residual thrust from the exhaust, that the performance tables take it into account in the POH. At high speeds it can approach 10% in extreme cases, but is usually less.

It is something like 50 kg of thrust on the ATR. Not even enough to get it rolling with brakes released.

Whilst I respect your expertise in many things relating to ATRs and Dash-8s, there were other turboprop powered airliners before them.

Wikipedia wrote:
Bristol Britannia; Bristol Proteus engine
Maximum power output: 3,320 shp (2,475 kW) + 1,200 lb (5.33 kN) residual thrust giving 3,780 eshp

That's 13.8% residual thrust.

Back when I was young, "eshp" was a recognised term, but it doesn't seem to feature so much these days. Maybe modern turboprop engines are so fabulously efficient it is negligible as you say. :scratchchin:

EDIT - I have found a figure for the PW150.... and I'll leave it there. :wave:


Engine manufacturers sell power so they will book keep every possible bit of power they eek out, be it shaft or thrust power. As you found, ESHP is still very much a figure of merit.
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