maths :?:
I think you have beaten him…
Ive said that before, queue IRONMAN responding with…
“Gurkhas are ten Times heavier than an M1 carbine”
Wanker!
<giving up completely on arguing with our resident troll>
Quoting static thrust is also misleading for real world applications - the defining thrust requirement for an airliner turbofan is the top-of-climb state, where the aircraft will be moving at 300kts or so (can’t be bothered to check out the real numbers) giving a large ram drag value.
As given airliners will need approximately the same thrust at top of climb, this means that changing the bypass ratio (and hence frontal area) will give different static thrust values for the same effective thrust at top of climb.
This effect means that for the cruise condition there is an optimal bypass ratio (around 11:1 or so for a real engine - not exactly sure), while some of the latest engines (GE90 for example) have actually got bypass ratios larger than optimal. This is driven by accoustic requirements at airports rather than efficiency, as the weight/efficiency penalty isn’t all that big.
Oh, incidentally this is why engines have different numbers of rotor and stator blades on each stage, or at least on the bypass section. If the rotor and stator numbers are the same for a stage it ends up effectively tuning the airflow and producing pure tones - a very bad thing.
Indeed, but manufacturer’s websites don’t quote anything more than static thrust! I can only crunch the numbers for the thrusts and masses available. 
He’s only going to read the word “fan” and ignore the fact that you were talking about turboFAN engines instead of turboJET engines & claim he was right… :roll:
So, you’re saying a jet angine 10 times the size of another weighs about the same? Really? For crying out loud. Listen to yourself. How pitiful.
Turboshaft Engines
CT7-2A
Diameter: 27 in.
Weight: 429 lbs.
CT7-8
Diameter: 26
Weight: 537 lbs.
That’s a difference of 1 inch and 108 lbs. Imagine if one were twice the diameter of the other. Not turbofan either. You’ve already seen this.
Nobody here believes that a jet engine 10 times the size of another weighs about the same, or could using current technology without producing one for the purpose thathad a power output so weak it could not be called a useable jet engine.
The statement was absurd, I’ve proven it, and anyone who supports it is being obstinate to a degree that it is demeaning to one’s self.
Before you demean yourselves further, provide us the specifications on aircraft jet engines which show that one with a particular diameter weighs about the same as another with a diameter anywhere near 10 times the size of the first. If you can do that (but you cannot) you will redeem your silly selves.
The harder you try to find such proof, the more you will realize how ridiculous your obstinance is, and how silly you look.
It’s the troll throwing strawmen again. No reference was ever made to existing engines (rather to a redesign using a different principle). Also, the size would have affected LENGTH, not diameter!
Back to google for you to find yet more irrelevant garbage. At least you won’t be posting drivel on here while you’re googling!
It’s the troll throwing strawmen again. No reference was ever made to existing engines (rather to a redesign using a different principle). Also, the size would have affected LENGTH, not diameter!
Back to google for you to find yet more irrelevant garbage. At least you won’t be posting drivel on here while you’re googling![/quote]
Feel free to try to find a jet engine of one type (such as tuboshaft) that has twice the surface area by square inches or centimeters and weighs “about the same as” the another that has half the surface.
Dude, you can talk about length, diameter, surface area, whatever. You will not be able to find such actual engines anywhere. One will weigh a great, great deal more than the other.
I implore you to try. :lol:
I’ll be around when you are ready to concede that you cannot find any such two engines.
I am beggining to think you have no common sence whatsoever.
Considering I haven’t been involved in your flamewar over this 10 times-the-size thing, will you permit me to post without being insulted?
Turboshaft Engines
CT7-2A
Diameter: 27 in.
Weight: 429 lbs.CT7-8
Diameter: 26
Weight: 537 lbs.That’s a difference of 1 inch and 108 lbs. Imagine if one were twice the diameter of the other. Not turbofan either. You’ve already seen this.
Turboshaft’s being similar to the turboshafts in that they are affected by more than their diameter. Note that of the two engines you are posting about (note - your diameters are wrong, btw). The CT7-8 provides much more power than the -2A.
One can only speculate where this difference in mass comes from without the drawings and associated design documents, but I can assure you only a small amount will be coming from increased diameter. As I politely pointed out at the end of my (very fair) analysis of your turbofan figures, for turboshaft’s your really need to substantiate what is included in the engine mass - e.g. is the equipment for producing useful work from the engine included in the mass figure, such as the gearboxes required to drive a rotor.
A little analysis to show where your use of those turboshaft numbers is going wrong
(first off - the correct figure according to GE’s website is a 25 inches dia for the CT7-2, and 26 inches dia for the -8. Your masses are however correct)
Now, taking the -2 as the baseline, the -8 has a mass 1.25 times the -2. Now taking as a very rough assumption (in fact, entirely incorrect, but this errs on the side of favouring your contention, so please forgive it) that the -2 is a cylindrical lump of homogenous material, diameter 25 inches, length 47 inches, it has a volume of 23071 cubic inches. The -8 by comparison, has a volume of 25909 cub inches. So the -8 should be only 1.12 times heavier by this method. In truth it’s 1.25 times heavier - and this is despite the fact we’ve assumed a homogenous cylinder.
If we were to be more realistic and assume a proportion of empty space within the engine, the numbers go even further against your use of these numbers to back up your claims. The weight of the engine ISN’T scaling as you’d expect with diameter. There are more complex causes of the weight increase involved in the detailed design of the engine.
Although that said, diameter is a red herring in this discussion to begin with. Removing the stator blades isn’t a question of increased diameter - as others have pointed out it is a case of increased length, and that length is “empty” space, with less material in terms of blades (which are heavy little buggers, believe me!) and more material in terms of casing and shaft. The approximation that the loss of the blades will balance out the gain in casing/shaft is conjecture, I’ll give you that, but it isn’t an unreasonable first approximation and certainly not absurd.
The statement was absurd, I’ve proven it, and anyone who supports it is being obstinate to a degree that it is demeaning to one’s self.
I don’t know what proof you refer to, but the data from the GE website proves nothing other than an engine that produces more thrust weighs more. Which isn’t what anyone else seems to be discussing.
Can I take up on this offer?
Using GE’s website as a source since I know you can access it.
Two turbofans. One the F110-100.
Maximum Diameter (Inches) 46.5
Length (Inches) 182.3 - 232.3
Dry Weight (Lb.) 3,920 - 4,400
The other, CF34-10.
Max Diameter (Inches): 57
Length (Inches): 90
Dry Weight (Lb.): 3,700
Notice that the latter engine necks down CONSIDERABLY (almost half the diameter) from it’s maximum diameter at around half way along it’s length. We will however assume maximum diameter. This will increase the surface area and hence increase the surface area per pound and hence make any disparity even greater. However, as a conservative assumption, we’ll assume constant diameter (trust me, this favours your argument if anything).
Where a range of values is given, the bottom of range is taken for each.
Method used to find “surface area” is as follows, for you to follow through at home.
Circumference = max diameter * pi.
therefore
Surface area = circumference * length
Figure of merit = surface area / mass.
And here’s one I made earlier.
F110 = 3920 lbs with 26587 sq in. area - area/mass = 6.78
CF34 = 3700 lbs with 16116 sq in. area - area/mass = 4.35
So already we’re close even considering the aft half of the engine is probably twice as thick as it should be on the CF34. Allow me to adjust this yet again.
Now accounting for the fact that the diameter approximately halves mid way along the engine on the CF34, half the length for the original diameter, then add that to half the diameter for the other half of the length.
CF34 = 3700 lbs with 12087 sq in area - area/mass = 3.27
Now, as we can all see 6.78/3.27 = 2.07!
Two turbo fans. One with twice the surface area yet approximately the same mass.
OBJECTIVE evidence that size and mass of a gas turbine engine (in this instance of the turbofan variety) are NOT linked how you claim them to be.
It’s what you’re DOING inside the engine that counts, not how large it’s external dimensions are.
And from the outset I’ll be completely honest in this post rather than having to point it out later. Both the F110 and CF34 ARE turbofans, but one is engineered for an entirely different mission to the other. In otherwords - the detail is very different despite both being turbofans of similar mass.
EDIT: edited for a couple of typos
I understand that it is not directly proportional to mass. But you must understand the claim. It was claimed that a jet engine of X size would weight “about the same” as another 10 times it’s size. Then it was stated that if you made it thinner and longer (as with engines using a centrifugal compressor I can only assume) and removed the stators (if you did it would no longer be a jet engine because the stators are used by jet engines to create the increases in air pressure necessary for the engine to function), that you one could make a jet engine that was 10 times the size of another and weigh about the same.
First of all, if you removed the stators, it probably would not operate, or at least it would not operate not at any level of efficiency as to make if provide a level of performance great enough to be useable. If in such a case it would operate, it would require the addition of a great many compressor fans to overcome the lack of stators. This would ADD a lot of weight to the engine, not because of the fan blades themselves (composite materials, relatively light weiaght, but because of the disks or drum necessary to to hold them , which in an elongated jet engine, would also be elongated. If such an engine would run sufficiently without stators, it would probably consume a ridiculous amount of fuel and generate a pathetically low power output. Furthermore, removing the stators would not reduce the weight of the engine so dramatically as to aproach the needed reduction in mass to make the engine weight 1/10th as much, or appraoch the weight of the 1/10th sized engine. The engine would still have fan sections to genetrate air pressure. It would still have an impellor and numerous other aluminium, titanium, and steel components. Otherwise, it would not function. We are talking about jet engines, not rocket engines.
Take a look at some of the components inside a jet engine:
Those internal components are made of metal - steel, titanium, etc. They must be able to withstand tremendous pressures and tremendous heat. Theyt are not made of plastic or any other material that is 10 times as light as metal.
Now let’s consider that you have built a jet engine, somehow without stators, and it is thin and long. It’s housing has the same surface area as another which is shorter and much thicker. If you did this, you would still have to have a much longer drum or disk compressor in it with additional compressor blades (remember, you have removed the stators ( :roll: ) that was efficient enough to produce useable power. These components are heavy. Unless you reduce the weight of the internal components by some dramatic amount, you will not lighten the engine dramatically, regardless of the compressor type.
Reducing the weight of a jet engine would require reducing the weight of all of the major components. Now if you say, “How about a jet engine without gear boxes or this or that…” you are not making a jet engine. You are making part of a jet engine. You could make a piston engine without valve covers, an oil pan, an exhasut system, an intake breather, etc, and it would run (perhaps not long), but do you have a useable piston engine? No, you do not. Therefore, a jet engine is a jet engine, otherwise you are comparing a jet engine to a half of a jet engine, and we are not talking about partial engines, but real, functional, useable ones.
No matter how you fenagle it, you cannot reduse the weight of a jet engine enough to make it 10 times lighter than another that has the same physical surface area and still have a fully functional, useable jet engine.
I imagine that I that it might be possible to build a jet engine with an aluminium garbage can and some sheet metal, with enough work and research. But what kind of RPM could be gotten from it? 100, 300, perhaps 500 rpm? How long would it withstand the heat generated? Perhaps 3 minutes? 7 minutes before the thin aluminium casing (garbage can) gets red hot and either burns awar or wars and collapses?
[b]There is no way with current technology to make a jet engine 10 times the size of another that weighs the same if it is to be called a real jet engine. If there were, General Electric, Rolls Royce, and others would be making them. But they are not. We have not yet learned to make materials that can withstand the tremendous temperatures and pressures generated by a jet engine that are strong enough and light enough to make a jet engine 10 times larger and weigh the same, or anywhere close to that.
Common sence alone tells us that, and the engines manufactured today reflect that it is not possible, ot it would have been done.
I hope if you read this with earnest, because I am sure that you will realize after having read it, that such a claim is perposterous. I have already show that it is. The claim is absurd, and far surpasses current technology. Hence, it has not been done.[/b]
I don’t blame anyone for dreaming about such a possibility however. That is a key component of progress. That does not mean, however, that making such a claim, as though it were fact, and as though it could or has been done, is not perposterous. It truly is.
Someone who hasn’t just come in from a good night out can deal with this, but here’s some pointers (expect to see this updated in the morning)
-
Stators are NOT required for compression (or expansion for that matter). No, really, they aren’t. They are good, in that they make it more efficient, but they are not essential for compression. So, without stators, you can still have compression, even in an axial flow engine. Clear enough? Good.
-
AAAAAAAAAAAAAAAAAAHHHHH!!! It’s like banging your head on a brick wall. Pdf has explained the orginial HYPOTHETICAL concept at least once. I have re-stated it thrice in order to be absolutely clear, and yet EVERY SINGLE TIME IRONMAN refuses to read what I have written and hurtles off into his own special world. I will not restate again the original hypothetical redesign of a reference engine. Can we perhaps discuss another aspect of jet engine design? And this time, the answer must include such terms as ‘isentropic compression’, ‘polytropic efficiency’ and at least TWO equations of the form T02/T01 = (p02/p01)^(1/(gamma-1)) (apologies if I have the exponent the wrong way up, in my defence its almost 3 am). I don’t mean to exclude interested parties, but so far we have an interesting discussion involving at least three Masters of Engineering (I suspect festamus is another, or at least a well informed person in a surprising range of subjects) which is spoilt by a man who is a Master of Cutting and Pasting from Google.
I suggest air cooling of turbine blades.
Expect a large edit when I wake up and wish I’d left this until the morning.
I’ve already stated that you COULD build a jet engine without stators, but alas, nobody does. Removing them would require adding many compressor fans unless you want to reduce the engine’s output quite dramatically (so much it would be so innefifient as to be worthless), and that means you are replacing one component with another. Having a hard time grasping that? I see that you must be. How about this:
2+2-2=2 Is that easier?
In reality, since you would have to add many compressor fans to make up for the loss of stators to achieve good compression, you would be adding weight. It would more likely be something like:
2+10-2=10
Do you see the folly of such reasoning now?
Hypothetical? The oridinal claim was not made in a hypothetical light, at all. It was stated as if it were factual. What is hypothetical about “You can could make a jet engine 10 times the size and it would weigh about the same. This is because a jet engine is mostly hollow.” That is paraphrased, but it is precicely, in my words, what was claimed.
You, and he, in light of the information that I have provided, are now trying to say that the claim was made in a discussion of hypothetical design to make defense of it more plausible. It was not. Even if it had been, current materials do not allow engineers to achieve this. You might as well be saying, “You could make a car (a real car, capable carrying passengers, towing a small boat at highway speed, aerodynamic, etc.) 10 times the size of a normal car that would weigh the same!” What freaking alien race brought you the materials that would allow you to do such a thing???
It does not work. Jet engines are not mostly hollow. They are filled to the gills with metal components. Metal is heavy. Very small jet engines weigh hundreds of pounds, large turbofan engines weight thousands of pounds. Now unless you have found a plastic that can withstand the required pressures and heat that Rolls Royce and GE do not know about, obviously you are pissing into the wind if you claim a jet engine can be made 10X in size and weight the same. That’s why a number of REAL jet engines made by REAL engineers can vary in weight by thousands of pounds with less than twice the surface area (diameter? whatever?). I even provided you an example of two turboshaft (not turbofan) engines that are different in diameter by 1 inch, and the difference in weight between them is 80+ pounds. They are also of similar length. :roll:
Now, when you have made such an engine, we expect you to post a photo of your huge award in your tuxedo at the ceremony. :lol:
Read the original claim. To remove all doubt, perhaps you could post what you consider to be the original claim. Better yet, quote it at the start of a new thread, and we will go round and round in circles there too.
Please do bother to post what you consider to be the original claim, because I can’t help thinking we are still arguing different points, despite vast expenditure of words.
PS: ‘No, you post it’ and other facetious replies are unwelcome. I actually, genuinely, want to know what you consider the original claim to be, so that we can discuss the same points, not just a few similar sounding ones.
PPS: You’d never catch me in a tux. I much prefer my dinner jacket.
:lol:
Touché
I have read it. He deleted it to save face. All that is left are references to it in other posts. :roll:
AAARRRGGHHH!
You don’t understand what stators do! You don’t know the difference between an axial and centrifugal compressor (btw, the latter are shorter & fatter, not longer and thinner as you “can only assume”. You are a layman (and not a terribly well-informed layman at that) arguing with qualified engineers with degrees in the subject (or who have had the subject as a component of the course). You are still misquoting, and quoting out of context (everyone else on these threads seems to have grasped the context of the original claim except you - the post containing it has even been linked to), and you are accusing people of deleting posts.
You can create & knock down as many strawmen as you want, but it won’t get you anywhere.
OK, stators, in layman’s terms, so that perhaps you might understand the original contention in context:
All a stator does is straighten the flow. That’s it. It doesn’t reduce the amount of compression stages required, or increase the compression, or anything particularly remarkable, it just straightens the flow. This is because of a nasty little thing called “swirl velocity”. Each compressor stage not only pushes air into the engine in a straight line, but it also makes it rotate, or “swirl”, because the blades are rotating. A simple vector diagram (look it up) showing the velocities at the blade tip shows this clearly. The stator stage after each compressor stage straightenes this out. The same happens in the turbine stages. In an engine of normal length, if this straightening out of the flow does not occur, the thing will just beat the air around in circles like an expensive egg whisk.
The contention was that by increasing the length by a (10x) factor, the stators could be eliminated because the swirl velocity would be reduced sufficiently by friction with the wall of the engine alone. This seems plausible to the 3 MEnges posting.
These basic concepts are vital to the understanding of the argument, and no amount of random quoting from GE or Nasa’s “idiot’s guide to jet engines” will replace this.
Oh for crying out loud. You commit folly once more. It is you who do not know what stators do. They perform 2 funtions.
- Manage the direction of the airflow
- Increase the compression of the incoming air
Here’s the facts for you: (axial compressor)
NASA
“The job of the stators is to increase pressure and keep the flow from spiraling around the axis by bringing the flow back parallel to the axis. In this figure we show a computer animation of an axial compressor. The stators of this compressor are connected to the outer casing, which is split. The rotors are connected to the central blue shaft, which would be connected to the power turbine of the engine.”
“Each blade on a rotor or stator produces a pressure variation much like the airfoil of a spinning propeller.”
http://www.lerc.nasa.gov/WWW/K-12/cdtemp/airplane/caxiala.html
“What is the purpose of the stators in the compressor? Other rows, called stators, are fixed and do not rotate. The job of the stators is to both increase pressure and to keep the flow from spiraling around the axis by bringing the flow back parallel to the axis.”
http://www.lerc.nasa.gov/WWW/K-12/BGP/Devon/turbine_id_ans.htm
Notice the URL is a NASA web site. www.lerc.nasa.gov You know, the people that went to the moon?
“This, plus the ability to increase the overall pressure ratio in an axial compressor by the addition of extra stages, has led to the use of axial compressors in most engine designs, however, the centrifugal compressor is still favored for smaller engines where it’s simplicity, ruggedness and ease of manufacture outweigh any other disadvantages.”
http://www.geocities.com/nedu537/turbine/
So now you understand what stators do, let’s continue.
In fact, 20% or so of the power produced by a jet engine using an axial compressor is directly related to the increased pressure caused by the stators. 20%! 1/5th!
Let’s assume that you are using an Axial compressor. This requires a drum, compressor blades, and stators to increase air pressure. If the engine is 1/10th the size, you have decreased the weight of the engine significantly because it is much smaller. Now imagine that you have an engine with a centrifugal compressor using an impellor in an engine that is 1/10 th the size of another. You have an engine which has a much smaller impellor, and the resulting engine is much, much lighter. If you compared a centrifugal compressor engine which is 10 times the size of one using a axial compressor, you have made an engine that is very heavy, because you now have a solid steel impellor that is huge, and it would be extremely heavy.
If you reverse this process and make an engine with an axial compressor (stators) that is 10 times the size, the result is an engine that is very heavy because of the size of the drum, compressor blades, and stators. If you make an axial compressor engine that is 1/10th the size, you have an engine that is far lighter, but the huge impellor of the comparison engine would be huge and very heavy.
It does not matter if you make an engine that is long and thin and without stators, or short and fatter. You are adding weight to one you are making larger and removing it from the one you are making smaller. You cannot find an equal weith for a 10X difference in size with a machine composed of metal and which has a core of metal components. If you think you can make a jet engine that is really long and thing to make it have 10 times the surface area as one that is shorter and fatter, you are mistaken. The extended casing would add a lot of weight! Furthermore, it would be totally impractical.
You cannot manage a difference of 10 times in size with jet engines and acheive an equal weight with current materials. 10 times is simply far too much to change the size of a jet engine, made mostly of metal, and keep it’s weight “the same as” another (1/10th it’s size). Either way, you are adding weight and removing it at the same time. The difference of 10X size makes it impossible to make a jet engine that weighs the same as another. Jet engines are made mostly of metal, and metal is heavy.
Here’s both designed for large jet engines. Which compressor weighs more? Does it matter? You cannot do what you are claiming can be done with metal. If it could be done, jet engines would weigh 1/10th of what they do, for obvious reasons.
I understand that it is not directly proportional to mass. But you must understand the claim. It was claimed that a jet engine of X size would weight “about the same” as another 10 times it’s size. Then it was stated that if you made it thinner and longer (as with engines using a centrifugal compressor I can only assume) and removed the stators (if you did it would no longer be a jet engine because the stators are used by jet engines to create the increases in air pressure necessary for the engine to function), that you one could make a jet engine that was 10 times the size of another and weigh about the same.
[/b][/quote]
Thanks Ironman for that. I have gone back a second time to the original posts that are causing this. I will add them to the bottom of my post for ease of reference of others.
I’m well aware of what stators (and rotors for that matter) do and don’t - as crab_to_be correctly guessed, I’m another Aeronautical Engineer, although admittedly my education in gas turbines has been the (excellent) compulsory bits, having chose to get into the murky world of Composite materials for the non-compulsory bits!
As an engineer with no particular beef against you or anyone else here, I have to say pdf’s original claims were perfectly reasonable approximations. When talking about a hypothetical engine with no stators in an internet forum about WWII colour photographs, it would be perfectly reasonable for an engineer of pdf’s qualifications to make such approximations. I can promise you, engineers do it all the time!
I must admit I do feel a little guilty for taking you up on your offer of twice the surface area for the same mass. I had no doubt in my mind that it could be done before I went off and did it, because I know it’s a complete nonsense comparison of engines. So for that I apologise. I took the first fighter engine I could find, and just picked off a civil engine from the list I made for the mass v. diameter post. I was confident this would work because the number of stages in the military engine is quite different to those in the civil engine, which is FAR more efficient.
But this should serve to reinforce to you what pdf is trying to say. Empty space weighs very little! So ignore the external appearance of an engine! The casings that you see are really very light in comparison to the material that forms the engine stages. for a year after finishing my secondary education and before starting University, I worked for a company that manufactured engine casings for Rolls Royce. They’re not something you can throw around, but they weren’t dense, and the thicknesses - particularly for the compressor casings, weren’t that much at all.
Is it really so hard to believe that by removing the stators and increase the length of empty space between rotors, you could make the changes approximately weight neutral, when the working parts of the engine are a LOT more dense than the casings which contain them? It was never presented as a rigorous analysis, merely a good approximation by a knowledgable engineer. Challenging people to find an engine with twice the surface area but the same weight isn’t going to get you anywhere - these guys have done degrees in turbomachinery, or dissertations on gas turbines as part broader engineering degrees. I’m an Aeronautical Engineer myself, but I still tip my hat to their vastly greater knowledge of gas turbines. The likes of you and I are out of our depth, and no amount of GE’s list of engines or NASA-for-kids (or whatever they call their educational web sites) is ever going to cut it. Give it up.
As promised the original contentious posts which were NOT deleted - they’re still there earlier in this thread, if these are the ones you refer to.
Actually, you’re correcting them because you’re too dumb to realise they’re right and you’re wrong. While you’re having to look up Wikipedia to support your case, I’m relying on lectures/supervisions by people with letters like “FRS” after their name. I spent last year working in a place called the “Whittle Lab”, opened by the very same Sir Frank, and part of the department where both he and Charles Parsons did much of their work. In comparison, quoting Wikipedia like that is the mark of “googlebrains”, someone who thinks that google can think for them. It can’t. Now off you go and get an engineering degree (preferably in turbomachinery like mine) before you start showing off your ignorance again.
The word “fan” is used because people can’t be bothered to explain to clueless Walts like you that the operating principle of the axial compressor in a jet engine (and yes, this includes the “fan” section in a bypass jet) is in fact somewhat different. While it is possible to design and build a gas turbine engine which would run on the same principle as a fan, they would be about ten times the size and roughly 10% less efficient. The critical part of an axial turbine/compressor is the stator/rotor combination - this gets rid of the swirl component to the gas stream, and in most modern jet engines actually does most of the compression/expansion. 50% reaction seems to be typical for modern jets, although the cost/benefit of different reaction ratios is far from clear. It is also sometimes used to describe the bypass section simply because it’s a nice short convenient word - and even if I allow that (note that it refers to the whole section rather than individual parts) bypass gas turbines didn’t start appearing until well after the war.
In fact, the word fan is being used in much the same way as people say that aircraft fly due to the Bernoulli effect. Bernoulli has of course nothing to do with it, but it causes far less grief than trying to explain bound vortices, the Coanda effect and Kutta condition to people who can’t speak engineer.[/quote]
AND THEN LATER…
Just spotted this gem. Yet more proof you don’t understand what is going on. The roughly 10x increase in size is to allow the swirling to damp down without using stator blades, all the extra space effectively being air gap. Since you don’t need the stator blades at all and the casing is relatively light then the engine will probably actually be lighter.
The 10% figure is an approximation for using a vaneless diffuser with a centrifugal compressor. The size increase isn’t 10x, more like 2x probably (there’s a trade-off between size and efficiency here - decreasing swirl losses with extra size but increasing losses due to other frictional components).
The 10x in size figure is an estimation of what might damp down the swirl in an axial turbojet enough to allow the jet to work at all - I’m not even sure it is possible at all, and specific power will certainly be way down.
That’s very kind of you. I doubt I’ll be in Germany in the next year or so (although I do have an uncle who lives in Gedern so will probably turn up over there sooner or later) so you aren’t likely to get any PMs in the forseeable future.
So that’s where all the WMD went!!![/quote]
You have provided nothing that explains how a jet engine can be manufactured with current materials (an efficient one, a useable one, one worth making) that is 10X the size of another and would weigh about the same. Current jent engine technology does not support your fantasy, else it would be done. But it is not.
It was a ridiculous claim.
Isn’t the entire point that removing the stators isn’t worth doing, even if it is possible, because it is more inefficient? Nobody’s claiming that engines should be ten times bigger. Pdf merely said removing the stators would result in an engine possibly ten times bigger.