TF-30 Engines

[FlyGuyF119]

Two weeks ago I met a retired F-14 pilot that flew the A model and since i'm a jet mech I asked him questions about the engines and their performance.

He stated that the TF-30's were strong and overall pretty good. However they had issues with compressor stalls above Mach 1.

 

He said you had to bring the aircraft out of burner, and leave the throttle's at MIL power until it stopped. I asked: What about just taking them to idle? His response was you would never do that, and that it was not recommended. He said when it happened the aircraft would shake and you would hear rapid popping from inlets. Just a thought for a system failure.

Edited October 5, 2015 by FlyGuyF119
tpyo

[Sid6dot7]

I asked: What about just taking them to idle? His response was you would never do that, and that it was not recommended.

 

 

And he's right. :)

 

Cutting the throttle back to idle when in a rotating stall in that flight regime and power setting could lead to a compressor surge, which will most likely lead to severe damage to the engine. Due to gas flow oscillations (that's the shaking and popping) the (especially larger) blades are highly stressed. In the worst case the pressure in the compresser breaks down completely (deep surge), the gas flow reverses for a moment, hot gas/flames from the combuster shoots through the compressors stages and just burns them to death or break them because of the sudden change in force direction.

Going back to MIL will reduce the pressure in the system but sustains it, dampens the oscillations and so breaks the stall cycle.

 

I once attented a rig test for an industrial gas turbine compressor. At the end of all important tests they decided to test its surge stability, it never came to a surge but the vibrations of the rotating stalls shook the whole building. :eek:

 

 

But yeah, simulating things like that would be :thumbsup:. Or at least implementing such well known instabilities.

Edited October 5, 2015 by Sid6dot7

[FlyGuyF119]

Heck ya man, I've worked on turbine for a decade now and have heard of bad story's of engine destroying themselves. Since a few do some odd things too. Bird strikes are always a fun mess :)

[FlyGuyF119]

I hope they make it with the F110-GE-400 engines. They're far more powerful and more reliable. And the turkey feathers look awesome on it! "For you non-engine guys, turkey feathers are the outside parts to the divergent nozzle segments. "

[NORTHMAN]

leave the throttle's at MIL power until it stopped.

 

Can you clarify what is MIL power! I'm a bit lost right now...:helpsmilie::thumbup:

[ff4life4]

Can you clarify what is MIL power! I'm a bit lost right now...:helpsmilie::thumbup:

 

Military power. Max power without afterburner

[streakeagle]

Keep in mind the TF30 was cutting edge technology when it was originally developed for the subsonic non-afterburning F6D Missileer and first used in the F-111 with an afterburner. The benefits in fuel efficiency and power density at subsonic speeds were too good to "bypass".

 

While the design was far from optimal for a supersonic dog-fighter, some of the worst engine-related F-14 accidents were caused by turbine blade failures. Strangely enough, I don't see any specific information about that in the TF30 wiki entry. I remember quite well a news story about a subcontractor substituting substandard materials that led to many of the blade failures, not unlike the F-15 Eagle with defective longerons causing the nose to snap off while pulling rated g-loads within rated lifetime.

 

As it turns out, the much later F100 engine selected for the F-15 and F-16 proved to be almost as troublesome. Partially fixed by retrofitting digital controls and a small reduction in rated output, it was ultimately fixed the same as the TF30... replacement with a more modern, better engine. Co-incidentally(?), the TF30 and F100 were both designed by Pratt & Whitney, while the principal replacement (and superior?) was the GE F110.

 

I understand those that want the best possible aircraft, i.e. the F-14D in its final configurations. But the original, as-delivered F-14A is far more interesting to me, requiring far more skill to fly the aircraft to its strengths. So, I will be extremely happy if all the known limitations of the TF30 can be reasonably modeled in the Leatherneck release :)

[FlyGuyF119]

Thats a good point there Steakeagle, and i know all about F100-100's "Changed one too many UC's in my day." haha

[BlackLion213]

Two weeks ago I met a retired F-14 pilot that flew the A model and since i'm a jet mech I asked him questions about the engines and their performance.

He stated that the TF-30's were strong and overall pretty good. However they had issues with compressor stalls above Mach 1.

 

He said you had to bring the aircraft out of burner, and leave the throttle's at MIL power until it stopped. I asked: What about just taking them to idle? His response was you would never do that, and that it was not recommended. He said when it happened the aircraft would shake and you would hear rapid popping from inlets. Just a thought for a system failure.

 

I've read the same, that above either Mach 1.2 or 1.4 the minimal throttle setting is mil-power.

 

I'm not surprised that he thought the TF30 was "pretty good overall" and powerful under the right conditions. It's an engine that people say a lot of different things about, because it's performance is really subject to conditions - more so than other modern engines.

 

I'm very interested to learn more about LNS' rendition. It was a powerful engine at low altitude and in zone 5 afterburner. If you spent all of your time below 10,000' and in burner, you might not think that there is anything wrong with it. However, load-up the Tomcat and stick to mil-power, especially above 25,000' and below 250 knots...there's not much there when you advance the throttle. Also, it burned a huge amount of fuel in afterburner - more than the J79! So, nice fuel economy at cruise, not so good in burner, but you need burner to really accelerate, climb, or maneuver at altitude.

 

One thing that will be interesting is that a lot of multi-player engagements happen at low altitude (at least according to a recent forum post). Many players may continue to do this to avoid long-range shots from the Tomcat, only to find that the F-14A is surprisingly tough opponent below 10,000', because the TF30's performance is so much better down low.

 

In any case, LNS is also doing the F-14B, so F110 goodness will be available to those who want it. That engine is a MUCH better match for the airframe and really opens up the performance envelope (it was quite the monster with those F110s, insanely good climb and acceleration). However, the F-14A/TF30 will be an entertaining combination for DCS and it can perform if you learn it well. A Tomcat driver (actually from VF-213, just after their transition to the F-14D from the F-14A) told me that when they do ACM practice, F-14A's would still routinely beat F-14B/D's. So it's not just about the engine.

 

I do have a questions for LNS: does the TF30 cough? As in, are there engine behaviors besides flame-out? (which is all the aerosoft F-14A does) Or are "coughs" a euphemism for flame-out? If so, are these "coughs" included?

 

Best,

 

Nick

[BlackLion213]

I understand those that want the best possible aircraft, i.e. the F-14D in its final configurations. But the original, as-delivered F-14A is far more interesting to me, requiring far more skill to fly the aircraft to its strengths. So, I will be extremely happy if all the known limitations of the TF30 can be reasonably modeled in the Leatherneck release :)

 

I see we are of the same mind set and great post!

 

Some of the Tomcat's problems was also because it was one of the first airframes that could maneuver well at really high AOA (especially compared to prior aircraft - an unslatted F-4 or F-104 start buffeting at 6-8 units of AOA).

 

In fact, when the F-4E's got maneuvering slats with improved AOA performance, there were reports of compressor stalls in the J79 - very rare before this, but not nearly as common as the F-14 with the TF30.

 

It took a while for jet engine manufacturers to create an engine that was powerful, reliable, and fuel efficient.

 

The real shame, was that it took the Tomcat longer than it's USAF counterparts to receive these improved engines.

 

-Nick

[Cool Breeze]

I hope they make it with the F110-GE-400 engines. They're far more powerful and more reliable. And the turkey feathers look awesome on it! "For you non-engine guys, turkey feathers are the outside parts to the divergent nozzle segments. "

That's one area that I keep getting confused.... The F-110 lead to the "B" model, an overall better engine. We are getting the A/B Tomcat. I guess this is something that only Leatherneck could decisively tell us. Are they modelling both engines? Giving us a choice in the difficulty of piloting the TF-30 with is associated compressor issues. Or is the A/B designation just used for "A" models upgraded to the F-110, and not a production "B" model. I think pulling back the throttle from afterburner and having a chance your engines eat themselves well always be interesting!

[FlyGuyF119]

Well, thats all great info. I wonder how high the PPH will end up being per engine. In MIL and in full Burn.

 

Not too long ago I read Bob Hoovers book and he accounts for one of the first encounters with compressor stalls in a F-100 with a J79 prototype powering it. He said it more or less scared the poop out of him. Therefore I hope to also get the same fright out of compressor stalls in the F-14 and other Aircraft.

 

Also just looked up cross sections of the TF30 and it blows my mind that they were still using a Can-Annular design...

The oil allowable oil consumption rate is mind blowing also. But here some good info.

http://www.ausairpower.net/PDF-A/engines.pdf

[BlackLion213]

Also just looked up cross sections of the TF30 and it blows my mind that they were still using a Can-Annular design...

The oil allowable oil consumption rate is mind blowing also. But here some good info.

http://www.ausairpower.net/PDF-A/engines.pdf

 

:huh: It's cool that you have the insight on those technical details, there is a great mix of knowledgeable people on this forum, I learn new things daily.

 

The core design of the TF30 dates to 1958 - so it's not surprising that it used archaic technology, even when it entered service with the Tomcat in 1972. In spite of it's age, it was still the only operation afterburning turbofan at the time.

 

IIRC - fuel flow in zone 5 afterburner was around 58,000 PPH/per engine. Fuel flow for the F110 at zone 3 afterburner (highest zone for the F110) was almost identical (58,000 PPH), but that same fuel flow generated 30% more thrust. Nice improvement!

 

-Nick

[Tirak]

That's one area that I keep getting confused.... The F-110 lead to the "B" model, an overall better engine. We are getting the A/B Tomcat. I guess this is something that only Leatherneck could decisively tell us. Are they modelling both engines? Giving us a choice in the difficulty of piloting the TF-30 with is associated compressor issues. Or is the A/B designation just used for "A" models upgraded to the F-110, and not a production "B" model. I think pulling back the throttle from afterburner and having a chance your engines eat themselves well always be interesting!

 

You have misread their press releases. We are getting 2 different tomcat modules. One is a mid 80s F-14A, the other is a mid 90s F-14B. The A module will have the older TF-30s, and the B will be powered, like all Bs, by the F110.

[Cool Breeze]

You have misread their press releases. We are getting 2 different tomcat modules. One is a mid 80s F-14A, the other is a mid 90s F-14B. The A module will have the older TF-30s, and the B will be powered, like all Bs, by the F110.

Ah, thanks Tirak!

[Igor4U]

Pratt & Whitney TF30

 

Some P&W TF30 Engine Links:

 

Pratt & Whitney TF30

http://wiki.scramble.nl/index.php/Pratt_%26_Whitney_TF30

 

Pratt & Whitney TF30

https://en.wikipedia.org/wiki/Pratt_%26_Whitney_TF30

 

TF30 Engine

http://www.pw.utc.com/TF30_Engine

 

Pratt & Whitney's TF30 was the first dual-spool, afterburning turbofan engine to enter service with the military.

 

The program was launched in 1959 to develop a military engine with afterburning for sustained supersonic speeds. The first flight of the engine, designated TF30 by the military, was on December 21, 1964, in a twin-engine General Dynamics F-111A being developed for the Air Force.

 

 

Here's the Highest Thrust Variant of the TF30 Motor:

 

TF30-P-100

25,100 lb (111.6 kN) thrust (with afterburner). Installed in F-111F and in 1985-86, upgraded to TF30-P-111.

 

 

The Thrust of a TurboJet Engine with the Fuel Efficiency of a TurboFan, the TF30 was cutting edge technology in its' day. Great choice for the F-111 which was basically a high-speed low-level Fighter-Bomber conducting Interdiction and Strategic Attack Missions. But for an aircraft (F-14A) that could find itself violently Dog-Fighting with On-Off Hi-G load, Hi-AoAs, and rapid Full Range Throttle Movements - the TF30 wasn't optimal.

 

Example: From the Throttles in Afterburner Range, coming aft over the detent back to Military Power and below (No-AB), the procedure was to stabilize at Min AB, then walk one throttle at a time back into the Mil-Power Range. This was to minimize the chance that both engines would compressor stall at the same time.

 

Note: Coming out of AB back to Mil-Power was tough on the Engine for whatever reason. Had a WSO who had prior F-4 Time and I let him fly - he ripped both throttles out of AB and yes - One Engine rolled back. Had to shut it down in order to re-start it.

 

 

Also - worked with a Senior Maintenance Engine Tech. HE said the fellow who designed the TF30 Engine Fuel Control went Insane. Point being that the TF30 Engine Fuel Control was an extremely complex and temperamental piece of equipment (responsible for many engine headaches for Maintenance).

[FlyGuyF119]

Funny i've heard the same about the guy that designed the UC for the F100-100

[FWind]

ferry range is F-14A looks better

[BlackLion213]

ferry range is F-14A looks better

 

I've heard the same, the TF30 was a bit more cruise efficient than the F110. It was a rather efficient engine in general, especially at low altitude - unless you are using the afterburners - then fuel consumption is quite huge.

 

I also cracked open the F-14A flight manual and learned a bit more about the TF30s interesting, but bad habits. So the TF30 commonly exhibited 2 forms of compressor stalls: brief, self-recovering stalls - the "coughs" and hung-stalls - the ones that cause big troubles.

 

The "coughs" are very brief stalls that make a loud noise (not always loud, loudness correlates with engine RPM and altitude), but does not damage the engine or cause an interruption in power. It's the TF30's "shot across the bow", since it occurs under the same conditions that will also lead to "hung stalls".

 

Hung stalls are the trouble makers, the real compressor stalls. When these occur, engine RPM will decay, thrust drops off, and turbine inlet temperature will rise. The engine does not respond to throttle movements (except shutting the engine down, or sometimes retarding to idle if your lucky). Interestingly, the TF30 is less likely to flame-out under these conditions than most engine, which is part of the problem. If the pilot doesn't shut down the engine, the engine will continue to heat-up and will catch fire. If a hung-stall occurs at normal airspeeds, the engine generally needs to be shut down completely and briefly wind-milled to cool. If not, the engine can catch fire during an attempt to relight.

 

These are the classic behaviors mentioned in the manual. There's also other things that can happen including catastrophic failure (though this is much less common with the 414A variant) and inlet buzz.

 

Anyway, I found it interesting and I'm hopeful that these behaviors make it into the LNS F-14A.

 

-Nick

[turkeydriver]

From the charts I've looked at, high and fast, the TF-30 starts climbing away from the F-110 with thrust, From Mach 1.7 on up above 30000 feet IIRC. The engine was a great straight and fast engine, so it was ideal for the F-111, not so much for quick speed, G, and acceleration changes though.

The axiom F-14A pilots used was "set it and forget it" when dogfighting in the F-14A. that is, set it in afterburner and don't touch it until you're done fighting, so you better win quick. Dale Snodgrass moved the throttles while fighting though, I'm sure he experienced his own share of compressor stalls. We should try to get retired CDR "Heater" Heatley to offer some advice on the subject.

[BlackLion213]

From the charts I've looked at, high and fast, the TF-30 starts climbing away from the F-110 with thrust, From Mach 1.7 on up above 30000 feet IIRC. The engine was a great straight and fast engine, so it was ideal for the F-111, not so much for quick speed, G, and acceleration changes though.

The axiom F-14A pilots used was "set it and forget it" when dogfighting in the F-14A. that is, set it in afterburner and don't touch it until you're done fighting, so you better win quick. Dale Snodgrass moved the throttles while fighting though, I'm sure he experienced his own share of compressor stalls. We should try to get retired CDR "Heater" Heatley to offer some advice on the subject.

 

I've heard the same. Supposedly, the TF30 powered Tomcats could break Mach 2 easier. More thrust above Mach 1.7 and 30,000 feet is no surprise (though I haven't seen the charts).

 

It was also a great engine at low altitude. Near mach 1 and sea level it makes 90% of the F110s thrust. One retired VF-14 pilot commented that the TF30 was a beast at low altitude, but he would have liked more thrust from 15,000 to 30,000 feet - thats were there was the biggest gap between the TF30 and USAF DACT opponents. Since ACM/DACT always have a hard-deck of 10,000' - most Tomcat crews didn't get to experience the impressive low altitude performance with any regularity. One advantage of being a TARPs pilot was the opportunity to fly the aircraft at low altitudes and better understand what the TF30 could do down there.

 

Like you said, the combination of less than ideal thrust between 15,000-25,000' with reliability issues during throttle changes was complimentary - Zone 5 during maneuvers was never too much thrust, so no need to move the throttles.

 

From what Dale Snodgrass has written, he has experienced lots of everything, compressor stalls and control departures. But he really knew how to make the Tomcat dance, opponents were often amazed with what he could do. Supposedly, he also experimented with asymmetric thrust as well - in the F-14A. Many F-14B and F-14D crews would use asymmetric thrust in DACT, but using it in the A was ballsy.

 

I'm sure LNS has found some good SMEs, perhaps even a few famous ones.

 

-Nick

[ehagendorff]

The TF-30 engines are definitely interesting. I have recently started reading and learning more about the F-14 in detail and have learned a lot about the engines and flight characteristics from my reading. The loud knocking described earlier and the subsequent stall is modeled in Aerosoft's version of the A model.

 

They also model hot starts and engine fires, so if you don't start the aircraft properly from C&D you can kill the engine just trying to start it. The way to do this is to advance the throttle early (basically right when you hit crank) before the engine is spooled and it dumps a bunch of jet fuel in and then when it ignites you get an engine fire and can lose the engine. You can also get hot starts as well which is a more mild version of this same scenario, (you skip the engine fire and melted blades.)

 

You'll see this in the gauges, the TIT (turbine inlet temperature) gauge will rise before the RPM gauge (quite a bit actually). If you see this you know to expect a hot start or possible engine fire.

 

In flight you can cause compressor stalls a number of ways as well, throttle movement as described earlier, as well as aero (high aoa, sideslip, altitude/mach) or poor management of the aircraft can induce them as well, (typically when the throttles are lower or below 80%). You can sometimes get hot starts and engine fires recovering/restarting after a compressor stall as well.

 

I am very much looking forward to Leathernecks version of the F-14 and look forward to breaking the aircraft as much as flying it! I believe it will be leaps and bounds better than any other simulation of the F-14 to date!

 

Also here is a bit about compressor stalls with the Aerosoft F-14X.

 

Here is a bit about hot starts/engine fires.

I thought I saw something where it covered all the problems you could have in one video but I guess not.

 

Can't wait for the full fidelity DCS F-14A/B!! :pilotfly::joystick:

[turkeydriver]

I've heard the same. Supposedly, the TF30 powered Tomcats could break Mach 2 easier. More thrust above Mach 1.7 and 30,000 feet is no surprise (though I haven't seen the charts).

 

It was also a great engine at low altitude. Near mach 1 and sea level it makes 90% of the F110s thrust. One retired VF-14 pilot commented that the TF30 was a beast at low altitude, but he would have liked more thrust from 15,000 to 30,000 feet - thats were there was the biggest gap between the TF30 and USAF DACT opponents. Since ACM/DACT always have a hard-deck of 10,000' - most Tomcat crews didn't get to experience the impressive low altitude performance with any regularity. One advantage of being a TARPs pilot was the opportunity to fly the aircraft at low altitudes and better understand what the TF30 could do down there.

 

Like you said, the combination of less than ideal thrust between 15,000-25,000' with reliability issues during throttle changes was complimentary - Zone 5 during maneuvers was never too much thrust, so no need to move the throttles.

 

From what Dale Snodgrass has written, he has experienced lots of everything, compressor stalls and control departures. But he really knew how to make the Tomcat dance, opponents were often amazed with what he could do. Supposedly, he also experimented with asymmetric thrust as well - in the F-14A. Many F-14B and F-14D crews would use asymmetric thrust in DACT, but using it in the A was ballsy.

 

I'm sure LNS has found some good SMEs, perhaps even a few famous ones.

 

-Nick

 

I thought the TF-30 was special at low altitude and Mach 0.9 in the tomcat, but the F-110 had insanely high thrust in the same regime- installed in F-14 its quoted ~27,000 lbs of thrust but at mach0.9 and sea level in the F-14 I think it makes something like 35k lbs of thrust. Don't remember where I saw that though, so check me.

[BlackLion213]

I thought the TF-30 was special at low altitude and Mach 0.9 in the tomcat, but the F-110 had insanely high thrust in the same regime- installed in F-14 its quoted ~27,000 lbs of thrust but at mach0.9 and sea level in the F-14 I think it makes something like 35k lbs of thrust. Don't remember where I saw that though, so check me.

 

I don't think it was 35,000 - 30,900 is what I read and I think that comes from an article written by RADM Gilchrist in the early 2000s (discussion of Super Hornet vs Tomcat in an aviation magazine). It doesn't get quite the bump that the TF30 sees, but it definitely makes more power with speed.

 

You're right - the TF30 performed well in the Tomcat at low altitude and speed.

 

The Tomcat's long, straight intakes really help the TF30 to make thrust at high speeds, but they also cost both the TF30 and F110 thrust at very low speeds.

 

My recollection of performance:

 

Engine____Installed________Static______SL@M0.9

 

TF30_____17,077_________20,900______28,000

 

F110_____23,400_________27,600______30,900

 

Installed thrust takes a hit (thats installed at SL and airspeed of 0 kts), but the TF30 gains 33% from static at M0.9. The F110 gains less (11%), but that still is a ton of power. :D

 

Flying fast and low-ish, the TF30 doesn't feel underpowered. Head up to 20,000' at mil power or less - different story. :(

 

The F110 doesn't feel underpowered anywhere - all I have to say is double dirty immelmann... ;)

 

 

-Nick

Edited October 28, 2015 by BlackLion213

[turkeydriver]

I must spread rep around before....... That's it, good stuff Blacklion213.