JET ENGINE

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#61

Let me check, cos im thick - as has been established when I didnt understand the right of Foreigners to join the US miltary etc, and how the Falkland islands have been our territory for nigh on 100 years longer than anyone elses…Ok we wont go there…

Im thick (Period) explain how the Opinion of IRONMAN (AERONAUTICAL QUALS NIL…) is superior to that of the man that is studying the principles of Turbo-Machinery. just me being confused.

Tell you what, Im not that big, infact I think the only way I have ever earnt respect is by stepping way form fights Im bound to lose and thus being aware of my limitations. Am I the only one to share this opinion?

STUPID - SIGNING OUT!

#62

Just to clarify I’m no longer studying but graduated last summer and am now working as a development engineer on Turbomolecular pumps. Look much the same but work very differently.
And so far as I can tell the reason he’s superior is because he doesn’t agree with me therefore I must be wrong :roll:

Edit: Just had a thought. Do they have early jets in Il2: Sturmovik?

#63

You welcome. It was interesting for me - a lots of information about Me 262 and Jumo 004 in russian but practically nothing about fuel for those Jumo… seem very strange…

Was J2 product of AG Farben and their “destructive hydrogenated coal” of “Bergius fuel” and a lot of another names for nazi’s sintetic fuel programme ?
According PRIZE : THE EPIC QUEST FOR OIL, MONEY & POWER, book of famous Daiel Yergin http://www.amazon.com/exec/obidos/tg/detail/-/0671799320/103-3900094-6120606?v=glance - at least 95% of all aircraft gasoline was sintetical… i see no reason doubt that this J2 was sinteticall thing too…

#64

Preatorian, I like you. But I must give my opinion. I personally disregard any author who writes that the US goes to war for oil. How silly. The US has never been “cut off” from oil by OPEC and has no need to go to war to gain access to what it already receives in undisturbed supply, and Iraq produces only about 4% of the world’s oil supply, and the US has not taken a single barrel of oil from Iraq without paying for it on the international market like everyone else. Besides, the US has spent more money on war than it would cost to buy more oil than it can use. He must be so anti-American he can’t think to do anything but write lies about the US because it suites his political agenda.

As for the the use of deisel in early jet engines, I find that strange. I would never have imagined such a fuel used for such an engine. it would have seemed to me that such a fuel would have too high a temerature for ignition. I guess that’s why it would include other ingredients?

#65

Preatorian, I like you. But I must give my opinion. I personally disregard any author who writes that the US goes to war for oil. How silly.
[/quote]
Who has wrote that ? D. Yergin ? I don’t have read whole book, only part about German “sintetic fuel programm”.

Sure. It allways point to discuss with some russians, who belive that USA started Iraq war by oil reason. I can see in this war a lot of reasons, but oil… hmm, i doubt…

I guess J2 was somekind of sintetic fuel (thanks to 2nd of foot for right question). And nothing about that J2 fuel, only “disel fuel for Me 262” or “aircraft oil J2”… and most imortant point - that J2 never named as “aircraft kerosene”.
Order to operate Jumo 004 (as well BMW 003): - starter engine, two cycle, gas B4, then Jumo 004 started and should gain to 3000 rpm using gas, then automatic switching J2 feed instead gas…
So, i guess, there were no problem with ignition - at 3000 rpm engine was pretty hot to burn inside anything…
Anyway, J2 was something that was hard to classificate - something between diesel and aircraft cerosene… i guess.
By the way, in 1940s USSR experimented with diesel engines in Pe-2 bomber. Near ground all things doing good, but after some attitude temperature of fuel fall down and diesel fuel just freeze in fuel lines…

#66

There is only a limited supply of oil in the world, why use yours now when someone else will pay awesome amounts for it in the future.

FFS!

a 14 year old studying Business in the UK can explain supply and demand and the idea of stock retention. Thankyou Britain for supplying my generation with an education!

#67

Thankyou Britain for supplying my generation with an education!

By saying that mate, you have just proved to everyone that you did not go to a state school!! :lol: :lol: (I did, but it was a rather unusually well funded one…) :oops: [/b]

#68

Apart from my spelling, which is medical not educationally damaged, I think my education has stood me in good stead, and I did go to a comp,

#69

Hey I found this again, I wondered where it had been whisked off to. :lol:
Nice to see that everyone (with maybe the exception of rustbucket) has understood my point.

By the way at the moment I am employed by a firm that works on the old test area the Germans used for jet developement (Versuchsfeld Trauen, now owned by DLR the German Aerospace people) it was also the centre that developed that interesting shooting round corners gadget for the MP43. After the war it was used as a rocket testing centre by the DLR but a lot of the old WW2 infra-structure is still standing quite an interesting place to work. (pdf27 if you want to visit drop me a PM I can show you around)

As far as:

Preatorian, I like you. But I must give my opinion. I personally disregard any author who writes that the US goes to war for oil.

from rustbucket, well I happened to be involved at the start of that last little adventure the US had in Iraq (you know the one that just seems to go on for ever, no matter how many times you press the escape key) and I beg to differ.

and the US has not taken a single barrel of oil from Iraq without paying for it on the international market like everyone else.

So the tankers I saw driving empty in and full out of iraq, escorted by obesely fat Americans in 4x4s a couple of days after the “end of hostilities” were all paid for fair and square? I dont think so.

He must be so anti-American he can’t think to do anything but write lies about the US because it suites his political agenda.

and you believe everything your government tells you because it fits your political agenda?

but anyway that’s going off topic, where was I ah yes

Seconds out round 2.

#70

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!!!

#71

Now now. Keep your political agenda neatly stuffed inside your panties. We know better than that.

#72

And we know better than you.

#73

Wake up now. It was you, not I who made the comparison between one engine and another 10 times it’s size, and then deleted your post upon seeing your dumbfuzzled booboo. And yes, if an engine increases in size 10x (as you stated), my statement is correct. It will indeed be more than 10% less efficient (contrary to what you said) due to the tremendous increase in weight.

Since you completely lack an understanding of physics, let me put this in middle school terms so you can grasp it.

For example, the cohesive force of water (producing surface tension) is tremendous when placed upon a tiny object. That’s why a pin will float on the surface of a bowl of water. But a pin 10 times the size of a regular pin will not float in a bowl of water. Does that help you understand your gross error?

Here’s another example:

A .177 cal. spring piston air rifle may have a muzzle velocity of 1,000 fps, and a .30 cal. pistol bullet may have a muzzle velocity of 1100 fps. Even though the .30 cal. bullet has far more than 10 times the force behind it than the pellet, the bullet does not move 10 times faster than the .177 cal. pellet.

You could also say that despite the fact that the pellet weighs less than 1/10th that of the bullet, it does not have 10 times the muzzle velocity!

Does that help too?

Likewise, the increased weight of an engine that is 10 times the size of another will yield an engine that is much more than 10% less efficient.

If you apply the adjusted 2X theory of your blunder to this line of thinking, you are attempting to adjust the comparison (mass) to meet the 10% decrease in efficiency (end result) that you stated, and that is backwards from determining the decrease in efficiency by comparing the mass. So, in effect you are attempting to salvage your blunder by adjusting the comparison instead of adjusting the end result…

…and that’s just f’d up.

No charge.

#74

Now now. Keep your political agenda neatly stuffed inside your panties. We know better than that.[/quote]

I have no political agenda, I personally dont give a shit whether it happened or not, I was there and saw it, you had it told to you by Fox.

#75

Go read the post again. The nature of the change in design is such that the weight is pretty much the same - the extra volume is all empty air space. The only extra metal required is the (relatively light) casing. So explain to me again because I’m obviously thick, why exactly is air the same weight as nickel alloy?

#76

Go read the post again. The nature of the change in design is such that the weight is pretty much the same - the extra volume is all empty air space. The only extra metal required is the (relatively light) casing. So explain to me again because I’m obviously thick, why exactly is air the same weight as nickel alloy?[/quote]

So the weight of a jet engine 10 times that of another is “pretty much the same” eh? So the metal casing of a jet engine is light weight eh? And the compressor fans too eh? It’s all featherweight stuff I see. A jet engine 10 times the size of another hardly weighs any more eh? 10 times the size and all those thousands of square inches of additional metal hardly weight anything eh? Right. :wink:

Is that anything like an empty 55 gal. oil drum weighing “pretty much the same” as a drum 10 times it’s size? I mean, they are both hollow, right? Afterall, they are made of aluminium aren’t they?

#77

Is that anything like an empty 55 gal. oil drum weighing “pretty much the same” as a drum 10 times it’s size? I mean, they are both hollow, right? Afterall, they are made of aluminium aren’t they?

Yes it is you pillock, a 10 times increase in volume of a drum does not equal a 10 times increase in weight unless the wall strength is also increased by a factor of 10 but if you care to read previous posts you may understand that this is a hypothetical example. FFS a potentially good brain is wasted in your head isn’t it?

#78

Speaking as the holder of an MEng degree, ironingman, you’re a pillock.

As to the question about diesel, you can develop a gas turbine engine to run on almost any fuel you like, provided that it is adapted accordingly. Most modern ones run on kerosene (paraffin), which has quite a high ignition temperature. The point of burning the fuel is to add heat to the compressed air at constant pressure (as far as is practicable) so that it can then expand as adiabatically as possible through the turbine.

As to the question of scale-up, as pdf says, it’s the length that’d be 10x bigger (in his estimation) to allow for the removal of the stator blades (which are heavy).

I’m not convinced that such an arrangement would even function, however, since the airflow pattern inside the engine would be terrible, even with the extra length to allow it to settle down.

And yet again, tinwalt, you’re arguing with somebody who has a degree in the topic.

#79

I’m not convinced either for an axial flow engine. Vaneless diffusers (much the same sort of thing) are used on some engines with centrifugal compressors, but really only on small ones where weight is more important than fuel consumption.
For axial flow engines, the two functions of the stators can be seperated out. The pressure change across them can be replaced by an air gap, effectively doing the same thing as the vaneless diffuser in the centrifugal compressor. The real problem is dealing with the swirl velocity - it will eventually be damped out by the wall friction, and you may even get some pressure recovery in the process, but this will take a lot of space and you will lose some energy to heat in the process.
Of course, nobody on earth would build an axial flow engine without stators - the size and efficiency benefits are absolutely massive.

Edit: While I remember, I’ve got an MEng too. It’s fairly recent though so I’m only an AMIMechE so far…

#80

I got my MEng in 2003 - I’m not a member of any of the institutions though (I’m eligable for IMechE and IEE and could possibly argue IChemE, but my 4th year project might prevent that) cos I’m working in intellectual property now and don’t see it as beneficial in any way. I did one of the few degrees that gets you multiple accreditations :evil: this did let me get my current job, cos there’s very few people who are qualified to work in both mechanical & electrical engineering.