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Thread: F-5 engine upgrade?

  1. #1
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    F-5 engine upgrade?

    With so many F-5's still in service. Wouldn't a engine upgrade or replacements be in order? The Tiger II is a fine little fighter but, it needs more power and range. Many are still around and have been recently upgraded with new radars and avionics. With two engines and hundreds still in service. There must be a large market? Russia would be a good candidate. Along with France, Germany, U.K., etc. etc.)
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    RE: F-5 engine upgrade?

    Unless there's a comparable sized engine with the thrust rating of the J85, then i don't think it's likely to be a twin engine replacement. Single engine repalcement have lot's more candidate engines, but that would require a serious modification to the aft fuselage and the intake. I think many would rather buy the up and coming advanced trainers/LIFTs for doing the same tasks.
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    RE: F-5 engine upgrade?

    As I recall the F-20 Tigershark(?) was the ultimate F-5 evolution but no one would buy it because they wanted the F-16 or that other one build by MDC. It was of course a single engine design.

    Regards.


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    RE: F-5 engine upgrade?

    yeh but the single engine turbofan would have been much better than the j85. of course th eus didn't want it to succede they had thier f-16 with j-?? (turbojet) - they tried flogging it but no one was that gulable. the people who wanted an f-5 replacment are starting now and you have -the at-50 (south korea -most promising), the iranin project (very little known), gripen (possible in this class), etc

    the us have got out of what looked IMHO to be a porfitable game but the countries that brought f-5s have either moved on to bigger aircraft and brought trainer or have just got combat caperable trainers.

    rabie :9

  5. #5
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    RE: F-5 engine upgrade?

    I still think it would be a good idea. With so many F-5's (A,B,E,and F's) and T-38's still in service. The market has to be big? That said, a replacement would have to be a direct replacement. (not a single engine) A new engine could offer more thrust and be more fuel efficient. Also, aren't they many other aircraft the use the J-85? Doesn't that Taiwanese jet trainer use J-85's (two)? Help me out. What aircraft use J-85's other than the F-5 and T-38?????
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    RE: F-5 engine upgrade?

    "Upgrading" to a turbofan just wont work on the F-5 just as it didnt work on the F-4.The j-85 is incredably efficient,infact the F-5 has one of the best power to performance ratios of any fighter ever made.Going to a turbofan would actually reduce range.When you compare the performance specs from the F-20 to the F-5,the improvement is surprizingly small compared to the gigantic difference in power.

    sauron-the taiwan fighter uses garret turbofans(bizjet engines).The other major user of the j-85 is the A/T-37 draggonfly.

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    RE: F-5 engine upgrade?

    What ever happend to the F-5 C/D?

    I know they did excist at one point, but I don't know much abouw it.

    JW
    Regards,

    Jeroen


    Cogito, ergo sum

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    RE: F-5 engine upgrade?

    follandGnat- Your saying that there is no way to improve on a jet engine that is going on 40 years old? Jet technolgy has come a very long ways in that time. Don't get me wrong. I personally know very little (some)about jet engines. Thought, that sounds like a pretty bold statement to me! Thats like saying that there is no room for improvement in the engine from a Mini Cooper.......That said, I yield to your expertise?



    Scooter
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    RE: F-5 engine upgrade?

    It would have to be of comparable size with little or no modification to the aircrafts structure. As for the cost many countries can't afford the cost of a new aircraft. Take for example: Philippines, Mexico, Tunisia, Morocco, to name a few! All countries that fly the F-5's now. There are some countries that maybe able to afford a small numbers of current generation fighters but, would augment those fleets with F-5's anyways. Brazil is one. They are looking to get 10-12 new block 50 F-16's in the near future. Unfortunately, thats all they can afford. In that case ungraded F-5's maybe a perfect choice to supplement there F-16's. Otherwords a poor mans hi-low mix! What do you think?
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    RE: F-5 engine upgrade?

    The F-5 is one of the aircraft that I see right now as being a big product when it comes to upgrades. You can get quite a lot out of this little fighter if you upgrade it correctly. New engines would be a good idea. The engines on the Ching-Kuo would be a perfect choice. Each produces nearly 10,000 pounds of thrust. That would give the F-5 twice the thrust overall. Likewise I've always believe the T-37/A-37 series should have had an engine upgrade.

    Fox-4!

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    RE: F-5 engine upgrade?

    Oh yeah, forgot to add this. The reason the F-4/Spey combination (which I know you are referring too) never worked is because the Spey was larger than the J-79 by a good deal. At least in width. It required greater airflow and thus the intakes had to be redesigned on the F-4K's and F-4M's. This resulted in a low of top speed at high altitude (although ironically the Spey Phantom was slightly faster down low than the J-79 Phantom) A turbofan engine will/has worked in the F-4. The Israli's proved that when they worked with Boeing on the Super Phantom. This was to have two PW1120 engines in it. They were more powerful and more fuel efficient than the J-79's. The aircraft demonstrated greatly improved performance. The only reason they never went through with the upgrade was that funding fell through. This same reason (at the same time period) was what killed the Lavi program. Too great, "what could have beens" aircraft killed by lacking of funding...such a shame.
    Fox-4!

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    RE: F-5 engine upgrade?

    PhantomII- Will the engines from the Ching-Kuo (IDF) fit in the F-5? They look a little big to me? Do you have dimensions? J-85's are very small for a jet engine.
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    RE: F-5 engine upgrade?

    like i said, if you can find an existing higher thrust engine with similar dimensions...but, no, you're not going to get a new engine design, it costs quite a lot these days just to come up with a new engine. The problem is that most engines are either much smaller than the J-85 or much larger. Even the F-125s are much much larger than the J-85s. It really is a remarkable tiny turbojet. It actually would cost less for a single engine replacement than a twin because modifying fuselages are relatively cheaper. Even a higher rating twin engine replacement most likely would have to redesign the inlets anyways for the higher air flow(unless that stays the same).
    Country::US of A

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    RE: F-5 engine upgrade?

    scooter-The F-20 is an F-5 with better engine performance.Is it a better jet overall?I dont think so,effiecencywise.

    phantom-The isreali F-4 "turbofan" your refering to is basically just a F-100 core.Yes its better than the J-79,but its not a turbofan(the outer spool is mainly for cooling.

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    RE: F-5 engine upgrade?

    Vortex- I believe I have established that there is a market for a J-85 replacement. That said, it would have to be of similar size and dimension. The thrust would be higher but, would need to be alot higher. Even 1,000 to 2,000 lbs would be of great improvement to the F-5 with little or no change to the intakes. If, indeed there is a large market for a J-85 replacement. Why would it not worth developing a new engine to replace it? Someone is missing out on alot of sales! (and support, parts, etc. etc.)
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    RE: F-5 engine upgrade?

    scooter-Ofcourse theres a market for engines more powerfull than the j-85,but theres no way in hell your going to make a turbofan with the same diameter as the j-85 thats more powerfull than the j-85.The j-85 is pretty much top of the line for turbojet technology,it moves huge volume of air very effecienly.Making large fans like on turbofans dont nessesarily make engines more powerfull,but spread out the useful load in the same kind of way 1st gear or overdrive spread out the usefull power in your car.

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    RE: F-5 engine upgrade?

    I'll just have to disagree and do alittle more research. Maybe a upgrade of the J-85 itself would be a better solutions? Thought, to says that we can't improve on a 40 year old design. Is just to hard to take at face value!
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    RE: F-5C/D & engine specs

    I'm not sure about the F-5D designation, but F-5C was the designation given to the modified F-5A's that were sent to SE Asia during the mid-60's for the Skoshi Tiger program which was a combat eval for the F-5 in Vietnam.

    I don't believe it will be practical to upgrade the powerplant of the F-5 series, if it was I'm certain one of the companies offering the F-5 upgrades would have jumped on it. I would imagine it is difficult to find a suitable replacement for the tiny J-85. The dimensions I have for the J-85-GE-21 are as follows: Dry weight 684 pounds, length 112.5 inches including afterburner, width 21 inches. For comparison the ITEC TFE1042-70 of the Ching Kuo weighs 1,360 pounds, is 140.2 inches long and 30.8 inches in width. Specific fuel consumption is similar between the two, with the newer engine having a slight advantage.

    Mike

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    RE: F-5C/D & engine specs

    mctodd- What do you define as practical? A replacement is needed the technolgy is available and the demand is high! Whats not practical? I see new jet engines (turbofan, turbojets etc.) develope for aircraft and helicopters all the time that are not produces in large numbers. Yet, one that could be produced in large numbers is not practical or should I say economical?
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    RE: F-5 engine upgrade?

    It sounds like the fog is appearing! Turbofan engines used in military aircraft are of a low bypass ratio type. They can also be known as bypass turbojets.

    Personally I'd refer to it as a low bypass turbofan... others will disagree!!

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    Engines

    Oh, I didn't realize the F125 in the Ching-Kuo was that much larger. Guess that won't work then. Sounded good at least. Well, what about GE taking the J-85 and updating it to more modern standards. Surely modern technology can help produce an almost identical engine with more power and better fuel efficiency. Now that I think about it, the J-85 is really a wonder of technology. Also, why did the USAF never put the J-85 in their very large fleet of T-37 Tweet jet trainers. The A-37 Dragonfly was fitted with them. Are they too powerful for the airframe of the T-37?
    Fox-4!

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    RE: F-5C/D & engine specs

    Scooter,

    I agree that it sounds like a good idea, with the relatively large numbers of Tiger II's still in service, with many of them going through various stages of systems upgrades. But, I still think that if it made sense from a economical/performance standpoint in relation to the cost of doing it, that one of the several companies involved with F-5 upgrades would have pushed it. I doubt we have thought up something here that the upgraders have overlooked, given that they are all working hard to get any perceived advantage over their competitors for these contracts. I don't know much about engines, but I doubt that in this case it will be possible to get a drastic amount of increased performance out of a similar sized engine to the J85. This may be possible, and if it is I agree it should be considered. A major structural change to accept a larger engine/engines may be too costly in return for the added capability it would give or for the amount of time some of the F-5 operators intend to keep the F-5 operational. Good question, but I still doubt that we are breaking new ground with this question.

    Mike

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    RE: F-5C/D & engine specs

    You maybe right. I have often wondered why a engine upgrade was not done with the F-5 (J-85)? That said, it doesn't mean its not possible. Even if you believe the argument that the J-85 cannot be improved on. What about aircraft like the Mig-21? Many still in service and being up graded as we speak. The Mig-21 may only be around for another 10-15 years but, the T-38 should be around til about 2040! I may not be around that long?
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    RE: F-5C/D & engine specs

    "What about aircraft like the Mig-21? Many still in service and being up graded as we speak."

    Not with new engines though Scooter. The various upgrade programmes for the Mig-21, e.g. Mig-21-2000, Lancer etc involve avionics and life extension developments. For the F-5 this is by far the better (and cheaper) path with minimal risk. Elbit systems from Israel offer a fairly good package which includes Multi-mode Fire Control Radar, Structural Modifications for new aerodynamic capabilities, the EW suite, HOTAS operation and head-out flight.

    Regards, Glenn.

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    RE: F-5C/D & engine specs

    Can somebody answer this..what about an m-88 or EJ-200 or TU RB199 with the afterburner removed? The engine length would be reduced , diametere would be 1 larger engine vs 2 smaller ones and weight would add a few hundred pounds but greater thrust.Also without afterburner , fuel consumption for a given thrust would be lower.Speed?I'm not sure..perhaps somebody could answer that.Is there a difference between an engine with say 4000lb wet thrust and 4000lb dry?

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    RE: F-5C/D & engine specs

    the exhaust velocity is much different, translating to a huge difference in transonic performance.
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    RE: F-5C/D & engine specs

    Glenn- As always your point is well taken. However the point that I was trying to make. If, you are upgrading aircraft with extensive avionics (i.e. Mig-21, F-4,etc.)for just 10-15 year. Wouldn't an engine upgrade be in order for a aircraft with one expected to last 20 to 25 years? (up to 40 in the T-38!)
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    RE: F-5C/D & engine specs

    Scooter,

    Yes, if the right engine can be found or even arranged for the upgrade. If not, then an overhaul would be the next best thing. Trying to modify a larger engine to fit a smaller body is undoubtedly going to cost more than you think and make the upgrade financially ineffective.

    Regards, Glenn.

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    RE: F-5C/D & engine specs

    The last time I heard they were doing anything on a j85 engine, they were trying to design a new nozzle to increase the efficiency of the j85's. i don't agree on removing the two j85's and putting a bigger one since it would require new structural body work to fit the bigger engine.. and it costs money. Many of the countries who uses the f-5's probably had a lot of experience with the j85's about 13,500 of these engines have been delivered..

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    RE: F-5 engine upgrade?

    i think a weapons upgrade would be better. like bvr missles.


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