Will the F120 be a good engine choice for the JSF? When the JSF enters service, won't it be basically a 20-year old engine? That doesn't make sense, to use a 20-year old engine in a state-of-the art new fighter (to me, at least). I know the F119 is also as old, but it's being developed further for the F-22 (isn't it?). 20 years is a long time in aviation. -- Alex Stoll N22YF [at] AlexStoll [dot] cjb [dot] net (remove NOSPAM to reply) http://www.Alex.AlexStoll.cjb.net/ http://AlexStoll.cjb.net/futureframe.htm AIM - N22YF
Well the 'new' F-120 really differs from the old one in having no variable cycle, new Rolls Royce fan,Philips FADEC from the Netherlands and other classified goodies. Perhaps GE and the armed services feel that the 'core' has much potential for the future but maybe they should derive an engine from NASA's IHPTET program instead. The Air Force Academy has a YF-120 here in Colorado, I've seen it, Jesus what a monster much bigger than an F-100
> Well the 'new' F-120 really differs from the old one in having no variable > cycle, new Rolls Royce fan,Philips FADEC from the Netherlands and other > classified goodies. > Perhaps GE and the armed services feel that the 'core' has much potential for > the future but maybe they should derive an engine from NASA's IHPTET program > instead. The Air Force Academy has a > YF-120 here in Colorado, I've seen it, Jesus what a monster much bigger than an > F-100
> Really, no more variable cycle? Why not? > -- > Alex Stoll > N22YF [at] AlexStoll [dot] cjb [dot] net > (remove NOSPAM to reply) > http://www.Alex.AlexStoll.cjb.net/ > http://AlexStoll.cjb.net/futureframe.htm > AIM - N22YF > BSchiltz <bschi...@aol.com> wrote in message > news:20001111005452.22137.00000012@ng-fw1.aol.com... > > Well the 'new' F-120 really differs from the old one in having no variable > > cycle, new Rolls Royce fan,Philips FADEC from the Netherlands and other > > classified goodies. > > Perhaps GE and the armed services feel that the 'core' has much potential > for > > the future but maybe they should derive an engine from NASA's IHPTET > program > > instead. The Air Force Academy has a > > YF-120 here in Colorado, I've seen it, Jesus what a monster much bigger > than an > > F-100
I don't know, but I can speculate. I believe that GE Aerospace made GE engine controls until 1993, when it was acquired by Martin Marietta. Lockheed Martin Control Systems was formed in 1995 as part of the Lockheed-Martin Marietta merger. Although GE has continued to rely on them for engine control systems support, they may have decided that it was time to bring in more competition. The ability to support offsets may have also been in their mind, although now that BAE SYSTEMS has purchased Control Systems, that might be less of a factor in the future. (Frankly, I don't know if buying from BAE SYSTEMS counts as an offset or not. I would guess not, but who knows?)
> I don't know, but I can speculate. I believe that GE Aerospace made GE > engine controls until 1993, when it was acquired by Martin Marietta. > Lockheed Martin Control Systems was formed in 1995 as part of the > Lockheed-Martin Marietta merger. Although GE has continued to rely on them > for engine control systems support, they may have decided that it was time > to bring in more competition. The ability to support offsets may have also > been in their mind, although now that BAE SYSTEMS has purchased Control > Systems, that might be less of a factor in the future. (Frankly, I don't > know if buying from BAE SYSTEMS counts as an offset or not. I would guess > not, but who knows?)
I didn't, either. Here's the press release from their web site:
June 15, 1999 Philips joins the JSF F120 engine team
Philips Machinefabrieken announces that it has concluded an agreement with the members of the Joint Strike Force F120 engine team (General Electric (GE), Rolls-Royce (RR), and Allison Advanced Development Company (AADC)) under which it will form and lead a consortium of Dutch, Norwegian, and Danish companies to join in the design, development, and manufacture of the F120 propulsion system for the JSF Alternate Engine Program.
Philips Machinefabrieken is part of Royal Philips Electronics of the Netherlands, and specializes in a wide range of production high-tech machines and systems, and in the manufacture of aviation components.
"Given the participation of the Dutch, Danish and Norwegian governments in the JSF Concept Demonstration Program in the U.S., Dutch industrial participation with the JSF F120 team was a natural," said Jim McNerney, president of GE Aircraft Engines, a business unit of General Electric Co. "The proven technologies and performance within Philips and Dutch industry and their healthy financial position and global reach will make them valued team members."
Frans Bastiaanssen, CEO of Philips Machinefabrieken said: "Besides significant growth opportunities in our global manufacturing network, through this agreement we also get access to a wide range of advanced technologies, which can find a wide application in other areas where Philips Machinefabrieken is active such as the Semiconductor equipment industry."
The Philips Machinefabrieken consortium will be fully integrated into the JSF-F120 team, and will develop world-class technologies to be applied to a wide variety of F120 engine components. The consortium members will have the opportunity to participate in other GE, Rolls Royce, and Allison programs.
Philips Machinefabrieken is the sole supplier of exhaust nozzle flaps and seals for GE F110 fighter engines and is expanding its relationship into other GE product lines. Philips Machinefabrieken also supplies the Inlet Scrolls for the Allison 250 engine.
For further information please contact: Philips Media Relations Jeremy Cohen, tel: +31 20 5977213, email: Jeremy.Co...@philips.com
I saw the F-120 in the USAFA Aero Lab when I visited for my 20 year reunion last year. The F-120 appeared smaller than the F-100 (by my recollection). Of course, I didn't pull out my measuring tape, just used my memory. I'd been out of the TAC cockpit for 13 years.
Nevertheless, an impressive piece of work. Several of us Aero Propulsion major types did a considerable amount of research on variable cycle gas turbomachinery during our senior year Aero project (1978-1979). Two of us wrote a 130 page paper on it. I pulled the paper out a few years ago and looked at the striking similarities between it and the F-120.
I'd love to run the F-120 on the test stand for a couple of hours and then run it in an F-22 or F-23 for a couple of hours!
>Well the 'new' F-120 really differs from the old one in having no variable >cycle, new Rolls Royce fan,Philips FADEC from the Netherlands and other >classified goodies. >Perhaps GE and the armed services feel that the 'core' has much potential >for >the future but maybe they should derive an engine from NASA's IHPTET program >instead. The Air Force Academy has a >YF-120 here in Colorado, I've seen it, Jesus what a monster much bigger >than an >F-100
Does anyone know of a URL I can look at to find some detailed information on the F-120 (from the ATF competition, not JSF) that gives project background, some specs (estimated or otherwise), pics, etc? I've already tried GE Aircraft Engines' website and did not find much info. Thanks!
> I saw the F-120 in the USAFA Aero Lab when I visited for my 20 year reunion > last year. The F-120 appeared smaller than the F-100 (by my recollection). Of > course, I didn't pull out my measuring tape, just used my memory. I'd been out > of the TAC cockpit for 13 years.
> Nevertheless, an impressive piece of work. Several of us Aero Propulsion major > types did a considerable amount of research on variable cycle gas > turbomachinery during our senior year Aero project (1978-1979). Two of us > wrote a 130 page paper on it. I pulled the paper out a few years ago and > looked at the striking similarities between it and the F-120.
> I'd love to run the F-120 on the test stand for a couple of hours and then run > it in an F-22 or F-23 for a couple of hours!
> >Well the 'new' F-120 really differs from the old one in having no variable > >cycle, new Rolls Royce fan,Philips FADEC from the Netherlands and other > >classified goodies. > >Perhaps GE and the armed services feel that the 'core' has much potential > >for > >the future but maybe they should derive an engine from NASA's IHPTET program > >instead. The Air Force Academy has a > >YF-120 here in Colorado, I've seen it, Jesus what a monster much bigger > >than an > >F-100
> Does anyone know of a URL I can look at to find some detailed information on > the F-120 (from the ATF competition, not JSF) that gives project > background, some specs (estimated or otherwise), pics, etc? I've already > tried GE Aircraft Engines' website and did not find much info. Thanks!
> Regards,
> Eric
> "Kurt R. Todoroff" <shark...@aol.comDELETEME> wrote in message > news:20001112142649.10864.00003096@ng-md1.aol.com... > > I saw the F-120 in the USAFA Aero Lab when I visited for my 20 year > reunion > > last year. The F-120 appeared smaller than the F-100 (by my > recollection). Of > > course, I didn't pull out my measuring tape, just used my memory. I'd > been out > > of the TAC cockpit for 13 years.
> > Nevertheless, an impressive piece of work. Several of us Aero Propulsion > major > > types did a considerable amount of research on variable cycle gas > > turbomachinery during our senior year Aero project (1978-1979). Two of us > > wrote a 130 page paper on it. I pulled the paper out a few years ago and > > looked at the striking similarities between it and the F-120.
> > I'd love to run the F-120 on the test stand for a couple of hours and then > run > > it in an F-22 or F-23 for a couple of hours!
> > >Well the 'new' F-120 really differs from the old one in having no > variable > > >cycle, new Rolls Royce fan,Philips FADEC from the Netherlands and other > > >classified goodies. > > >Perhaps GE and the armed services feel that the 'core' has much potential > > >for > > >the future but maybe they should derive an engine from NASA's IHPTET > program > > >instead. The Air Force Academy has a > > >YF-120 here in Colorado, I've seen it, Jesus what a monster much bigger > > >than an > > >F-100
> Nevertheless, an impressive piece of work. Several of us Aero Propulsion major > types did a considerable amount of research on variable cycle gas > turbomachinery during our senior year Aero project (1978-1979). Two of us > wrote a 130 page paper on it. I pulled the paper out a few years ago and > looked at the striking similarities between it and the F-120.
Forgive my ignorance, but can someone outline what variable-cycle is? Or point me in the right direction? I'm familiar with regenerators, is this something similar? I didn't find anything on topic in Google.
> "Kurt R. Todoroff" <shark...@aol.comDELETEME> wrote in message > news:20001112142649.10864.00003096@ng-md1.aol.com... > > Nevertheless, an impressive piece of work. Several of us Aero Propulsion > major > > types did a considerable amount of research on variable cycle gas > > turbomachinery during our senior year Aero project (1978-1979). Two of us > > wrote a 130 page paper on it. I pulled the paper out a few years ago and > > looked at the striking similarities between it and the F-120.
> Forgive my ignorance, but can someone outline what variable-cycle is? Or > point me in the right direction? I'm familiar with regenerators, is this > something similar? I didn't find anything on topic in Google.
> Does anyone know of a URL I can look at to find some detailed information on > the F-120 (from the ATF competition, not JSF) that gives project > background, some specs (estimated or otherwise), pics, etc? I've already > tried GE Aircraft Engines' website and did not find much info. Thanks!
> Regards,
> Eric
> "Kurt R. Todoroff" <shark...@aol.comDELETEME> wrote in message > news:20001112142649.10864.00003096@ng-md1.aol.com... > > I saw the F-120 in the USAFA Aero Lab when I visited for my 20 year > reunion > > last year. The F-120 appeared smaller than the F-100 (by my > recollection). Of > > course, I didn't pull out my measuring tape, just used my memory. I'd > been out > > of the TAC cockpit for 13 years.
> > Nevertheless, an impressive piece of work. Several of us Aero Propulsion > major > > types did a considerable amount of research on variable cycle gas > > turbomachinery during our senior year Aero project (1978-1979). Two of us > > wrote a 130 page paper on it. I pulled the paper out a few years ago and > > looked at the striking similarities between it and the F-120.
> > I'd love to run the F-120 on the test stand for a couple of hours and then > run > > it in an F-22 or F-23 for a couple of hours!
> > >Well the 'new' F-120 really differs from the old one in having no > variable > > >cycle, new Rolls Royce fan,Philips FADEC from the Netherlands and other > > >classified goodies. > > >Perhaps GE and the armed services feel that the 'core' has much potential > > >for > > >the future but maybe they should derive an engine from NASA's IHPTET > program > > >instead. The Air Force Academy has a > > >YF-120 here in Colorado, I've seen it, Jesus what a monster much bigger > > >than an > > >F-100
You could start by looking at www.jast.mil, this is the JSF official website it could provide a link to other possible F-120 websites. Or you could email lockheed-martin tactical aircraft division and politely ask them for any public brochures they might have on the F-120, or you could ask around at aviation week and space technology magazine.
: You could start by looking at www.jast.mil, this is the JSF official : website it could provide a link to other possible F-120 websites. Or you : could email lockheed-martin tactical aircraft division and politely ask : them for any public brochures they might have on the F-120, or you could : ask around at aviation week and space technology magazine.
I don't believe Lockheed Martin Aeronautics (nee Tactical Aircraft Systems) has any brochures or other public information specifically on the F120 engine. You'd be much better off contacting GE.
I should point out that the YF120 engine was used on both the YF-22 and YF-23...
Sadly the picture is rather unclear. From the discussion in the text, I have tried to piece together what it means.
1) 20 - 30% of the compressor flow is currently used as cooling air for the turbine stages
2) by using a variable opening, we can adjust this figure from a high value like the above, to a low value, or zero
3) as a result we can recapture all of this "lost" flow during the times when we don't need it as the temperatures are low, like during cruise where a 30% flow improvement would be significant (30% fueld savings?)
> Sadly the picture is rather unclear. From the discussion in the text, I > have tried to piece together what it means.
> 1) 20 - 30% of the compressor flow is currently used as cooling air for the > turbine stages
> 2) by using a variable opening, we can adjust this figure from a high value > like the above, to a low value, or zero
> 3) as a result we can recapture all of this "lost" flow during the times > when we don't need it as the temperatures are low, like during cruise where > a 30% flow improvement would be significant (30% fueld savings?)
> Did I get it right?
> Maury
Well I'm no expert but I dont think so.
My understanding is that the efficiency of jet engines is highly dependent on their operating regimes.
At Subsonic speeds high bypass ratio fans are a distinct advantage moving larges masses of air at lower velocity leads to lower losses due to turbulent flow etc.
In supersonic flight these are less efficient since moving large masses of air at low velocity limits the top speed in comparison with moving a lesser mass at a higher velocity
At Mach 3+ the ideal is the ramjet with no compressor/fan stage
Most current engines are optimised for one regime and are at best a compromise for other states. They use some variable geometry factors such as movable inlet cones to try to compensate but the engine itself operates in the same manner throughout all flight conditions.
It's my understanding that the idea of the variable cycle engine is that one can vary engine parameters like bypass ratio to produce better efficiency for more flight conditions
> It's my understanding that the idea of the variable cycle engine is > that one can vary engine parameters like bypass ratio to > produce better efficiency for more flight conditions
I'm familar with some of the older designs like the W67 and the French design, and with some of the newer 80's revivals - is this what the diagram was trying to show? If so, it's a terrible diagram!
> "Keith Willshaw" <keith_wills...@compuserve.com> wrote in message > news:8uq0sa$ghb$1@sshuraac-i-1.production.compuserve.com... > > It's my understanding that the idea of the variable cycle engine is > > that one can vary engine parameters like bypass ratio to > > produce better efficiency for more flight conditions
> I'm familar with some of the older designs like the W67 and the French > design, and with some of the newer 80's revivals - is this what the diagram > was trying to show? If so, it's a terrible diagram!
> Maury
Hey dont shoot me I just found the article I didnt write it :)
In article <9R2Q5.80001$x6.1678...@news20.bellglobal.com>, "Maury Markowitz" <maury_markow...@hotmail.com> wrote:
> "Keith Willshaw" <keith_wills...@compuserve.com> wrote in message > news:8uq0sa$ghb$1@sshuraac-i-1.production.compuserve.com... > > It's my understanding that the idea of the variable cycle engine is > > that one can vary engine parameters like bypass ratio to > > produce better efficiency for more flight conditions
> I'm familar with some of the older designs like the W67 and the French > design, and with some of the newer 80's revivals - is this what the diagram > was trying to show? If so, it's a terrible diagram!
> Maury
Wasn't the J-67 a licensed version of the Rolls-Royce Olympus?, aside from being licensed produced what other changes did it have.
<nx1...@my-deja.com> wrote in message news:8ur6u9$ntk$1@nnrp1.deja.com... > Wasn't the J-67 a licensed version of the Rolls-Royce Olympus?, aside > from being licensed produced what other changes did it have.
They were adapting it to bleed air from the compressor IP stages into the rear of the engine, just like the J58 - I think the original Olympus did this too (to lower pressure during startup IIRC). The installation was the interesting part, there was a large "valve" in the inlet ramp that could divert the air (all?) around the engine and directly into the tailcone.
The plan was that at high speeds the valve would close and the engine would essentially be turned off (idle? off?). The air flowing around the engine in the bypass duct would then flow into the afterburner and be burnt - thus forming a ramjet. As a result the plane it was licensed for, the F-103, was supposed to have a cruise speed of around M3.7 or so.
There are parallels with the J58 here, but it's been a LONG time since I last looked at that engine. It also takes ip air from the turbine, right?
But I'm still not sure I understand how this applies to the F-120. Looking at the diagram it appears they are taking a feed off of the hp stages of the compressor, then feeding that outside of the turbine. But the diagram is so unclear I can't see exactly what it's doing, it _looks_ like it's bypassing the combustors and exiting out the rear in the afterburner stage through a outer jacket, but that seems odd - is it burning there?.
And then there's those plates in the diagram aft of the turbine outlet cones, what are they? If they close off the turbine outlet and bleed the air back into the AB area then the setup is very similar to some of the 1980's French designs I saw (well at least I saw them in a French mag, Science et Vie IIRC), and perhaps the W67 too, but I'm not sure.
> Nevertheless, an impressive piece of work. Several of us Aero Propulsion major > types did a considerable amount of research on variable cycle gas > turbomachinery during our senior year Aero project (1978-1979). Two of us > wrote a 130 page paper on it. I pulled the paper out a few years ago and > looked at the striking similarities between it and the F-120.
Kurt, any chance for a quick primer here? I'm familiar with some of the basics, could you flesh out the details of the vari-cycle on the F-120?
Just as some aircraft employ variable geometry wing sweep designs that permit the pilot to tailor, even optimize, aircraft configuration in flight, the Variable Cycle Engine (VCE) reconfigures itself in flight for the ambient flight conditions. The previous terminology that we used twenty years ago was "Variable Area Turbine" or VAT. This is the key to understanding VCE.
Some of the previous persons who posted to this newsgroup were correct in their assertion that aircraft and engines are optimized for a particular design point. Therefore flight at any other point is not optimized, and thus, a performance penalty is realized (thrust and fuel flow, and even reliability). The VAT employs a variable geometry turbine inlet nozzle which controls the gas flow parameters through the engine according to the ambient flight conditions. (The turbine inlet nozzle is located aft of the combustor and forward of the turbine.) A FAT, or "Fixed Area Turbine" employs a fixed geometry turbine inlet nozzle. Being "Fixed Area" constrains the engine performance during "off design" flight conditions. The FAT nozzle is very analogous to the fixed area nozzle of non-afterburning engines, while the VAT nozzle is very analogous to the variable area fully articulated nozzle of afterburning engines. In fact, they serve the same purpose: to control the mass flow, temperature, and pressure characteristics of the gas flow through the engine. At this point, if you are mentally visualizing an orifice inside the engine (between the combustor and the turbine) that increases and decreases in size according to flight conditions (like the aperature in a camera), thus controlling the gas flow (air and fuel) through the engine, then you are correct.
The advent of the Digital Electronic Engine Controller (DEEC) made the VAT or VCE practical. The older hydro-mechanical engine controllers were limited to monitoring and controlling very few engine and flight parameters. Today's DEECs can monitor and control all of the engine parameters, and do so much faster than the hydro-mechanical controllers. As such, the engine is less susceptable to surge, stall, overspeeds, overtemps, etc. In fact, the DEEC can run the engine much closer to the surge line than the hydro-mechanical units could, which translates into greater thrust and lower fuel consumption and greater reliability (especially at high angles of attack and low airspeed conditions) through all flight regimes. The added task of monitoring and controlling VCE parameters is no big deal for a DEEC (providing of course that the software is written to include VCE algorithms). While we didn't address the issue of engine controllers in our paper, I seriously doubt that those old hydro-mechanical engine controllers could have managed a VCE sufficiently well to maximize the inherent benefits of Variable Cycle. Given two identical VCE engines, one with a hydro-mechanical controller and the other with the DEEC, the second will outperform the first.
The obvious drawbacks to VCE are the additional moving parts that are required to make this work, especially those that articulate within the environment of the hot gas flow, and there associated weight. However, we have observed gas turbomachinery reliability improve by an order of magnitude in twenty years. (I'm making a reference to my personal experience with our early TF30s and F100s.) Additionally, I did not experience nor did I know of a single TF30 nozzle failure in 1400 hours and 7 years of flying. The nozzle is exposed to extremely high temperatures and G loading (i.e. bending) during articulation.
The USAF chose the F119 engine because it was a lower risk proposition. I disagreed with their position based on empirical data and technical merit. However, I fully agreed with their position based on the political risk. The 535 moronic pedants in congress can and do twist reality and history to suite whatever agenda is politically popular and expedient for the moment. (Note that CONgress is the opposite of PROgress.) (I apologize for stepping on my soapbox for this brief moment.)
So, Maury, did I pass the test of "Quick Primer" or was the explanation not quick enough?
> Kurt, any chance for a quick primer here? I'm familiar with some of the >basics, could you flesh out the details of the vari-cycle on the F-120?
> So, Maury, did I pass the test of "Quick Primer" or was the explanation not > quick enough?
Yeah, but...
So basically the description you give here is that there's another "choke point" inside the engine behind the flame cans but in front of the turbine inlet face. This brings up a few questions for me:
1) you don't mention materials in your primer, but it would seem to me that this is as important as FADEC design due to the placement?
2) the diagram in question does not seem to illustrate such a choke, and instead referrs to a hp-stage bleed from the compressor. Comments?
Materials technology is a sine quo non in gas turbomachinery.
I visited the web site in your message, however, it was not available. I visited the web site from another posting and viewed the diagram in question. It had insufficient resolution and clarity for me to discern any information on the engine's operation.
> Yeah, but...
> So basically the description you give here is that there's another "choke >point" inside the engine behind the flame cans but in front of the turbine >inlet face. This brings up a few questions for me:
>1) you don't mention materials in your primer, but it would seem to me that >this is as important as FADEC design due to the placement?
>2) the diagram in question does not seem to illustrate such a choke, and >instead referrs to a hp-stage bleed from the compressor. Comments?
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