EBJ1248650 From United States of America, joined Jun 2005, 1932 posts, RR: 2 Posted (4 years 7 months 4 weeks 1 day 16 hours ago) and read 3517 times:
I understand the F-111 fleet, with the exception of the FB-111A/F-111G perhaps, was upgraded to the TF30-P-109 engine and as a result the airplanes had better performance. Try as I might, I can't find a source on the internet that indicates what the maximum thrust of these engines was. Anyone know what that figure was? Is the TF30-P-108 in the same thrust class? The -108 is used on the Australian F-111s.
PhilSquares From , joined Dec 1969, posts, RR: Reply 1, posted (4 years 7 months 4 weeks 1 day 12 hours ago) and read 3482 times:
Quoting EBJ1248650 (Thread starter): I can't find a source on the internet that indicates what the maximum thrust of these engines was. Anyone know what that figure was?
EBJ1248650 From United States of America, joined Jun 2005, 1932 posts, RR: 2 Reply 2, posted (4 years 7 months 4 weeks 1 day 11 hours ago) and read 3469 times:
[quote=PhilSquares,reply=1]Quoting EBJ1248650 (Thread starter):
I can't find a source on the internet that indicates what the maximum thrust of these engines was. Anyone know what that figure was?
O.K. According to Don Logan's F-111 book, the F-111A, EF-111A, F-111C and F-111E had their P-3 engines updated to P-109 standard. The F-111D P-9 engines were also upgraded to P-109 configuration. Am I interpreting this correctly that all modified engines would have had the same maximum thrust after the mod', 20,900 lbs according to the web site you directed me to. That would have constituted a thrust reduction for the F-111F. Is the web information regarding P-109 thrust rating accurate?
The scramble F-111 site shows the F-111s powered by TF-30-P-100/111/111+ engines rated at 50,200 lbs combined thrust. Were the P-111 engines the ones applied to the entire fleet?
TexL1649 From United States of America, joined Aug 2007, 238 posts, RR: 0 Reply 3, posted (4 years 7 months 4 weeks 1 day 2 hours ago) and read 3414 times:
Just rest easy knowing that they were always, forever and a day, under-powered by about 5-10,000 pounds at least. The Tomcat and F-111 were both cursed with the lousiest powerplants of any American 60's-70's combat aircraft.
Blackbird From , joined Dec 1969, posts, RR: Reply 4, posted (4 years 7 months 4 weeks 23 hours ago) and read 3384 times:
EBJ1248650,
The most serious problem with the TF-30 was it's poor compressor-stall/surge-resistance, which it would seem occurred at low airspeeds, at low-throttle settings, especially at high-alphas (high-G's/sharp-turns). This required the plane's throttles to be set within a relatively narrow-range when performing aggressive maneuvers (such as dogfighting) -- essentially you were flying the plane around the limits of it's engine, not the airframe (or the pilot)
It also being a turbofan appears to produce disproportionately higher thrust when on afterburner as a result of the duct-burning effect, (or more accurately a reasonable amount of thrust on AB, and not enough dry). Due to it's bypass-ratio, it probably lost more thrust at altitude compared to then contemporary turbojets (J-57, J-79, J-75).
The engines did have some areas where they performed well in. High-throttle settings (as mentioned before), high mach numbers (it can get into the Mach 3 range at altitude) and high-airspeeds (like when racing over the terrain a like 800 kts/Mach 1.2).
Since you pointed out a thrust discrepancy between the various TF-30 models, you sould also keep in mind that in addition to models, the thrust levels listed on virtually all engines are often underrated.
You've probably heard of a term called "Fudge Factor" -- it is essentially a misleading factor added into the equation (which can be any figure) to produce the figure you want everybody to see. For example the USN's old F8U/F-8 Crusader had an official maximum G of 6.5, but the plane was rated to actually do 1.5 times that figure at max which is between 9-10 G's (instantaneous G's at least). That's a big difference.
The CJ-805 which is a civilian version of the J-79 that powered the Convair-880, actually produces around 13,000 lbf at full power. I talked to a guy who for years as working with a bunch of people to buy a CV-880 sitting in the boneyards and refurbish it at least to museum-grade (if not flying status) -- while his project failed to the best of my knowledge, he had boxes and crates of information on the CV-880. In either case, most books on the CV-880, in fact most sources say the CJ-805 produces a thrust of either 11,200 lbf, to 11,650 lbf -- yet he has all sorts of documentation (which is obviously iron-clad accurate) that says it produces 13,000 (and it would better explain the climb-performance and acceleration of the CV-880).
It seems rather odd that you would lie about the thrust ratings of a commercial jet-engine, but the J-79 powered a lot of military aircraft such as the F-104, B-58, F4H/F-4 and I guess they didn't want our enemies to know the full thrust capabilities of our engines.
Blackbird
Let's hope I don't get a heart-attack, disappear, or get cancer or some dreaded disease...
Not long ago, that would have been true, but all the F-111Cs were changed over to the -109/-109RA engines in a program that started in the late 90's. Im pretty sure they also acquired a bunch of ex USAF -109s as part of the same program
The article makes reference to the program, as well as mentioning a thrust rating of 20,840lbs.
Another aim was to enhance commonality with the F-111G engine pool, with about the only major difference between the variants being a slightly angled tailpipe for one versus a straight pipe ( I think the C model has the angled pipe)
KC135TopBoom From United States of America, joined Jan 2005, 11704 posts, RR: 52 Reply 6, posted (4 years 7 months 3 weeks 5 days 10 hours ago) and read 3257 times:
Quoting Legs (Reply 5): Another aim was to enhance commonality with the F-111G engine pool, with about the only major difference between the variants being a slightly angled tailpipe for one versus a straight pipe ( I think the C model has the angled pipe)
Another difference between the F-111C and the F-111G (FB-111A) is the "G" has a slighly wider and longer fuselage, as well as the Triple Plow II inlets the F-111C (F-111A with F-111B wings and FB-111A landing gear) doesn't have. The F-111G also carries a heavier weapons load and longer legs compared to the F-111C.
Broke From United States of America, joined Apr 2002, 1322 posts, RR: 4 Reply 8, posted (4 years 7 months 3 weeks 3 days 21 hours ago) and read 3184 times:
The P-100 series of the TF-30 were TF-30's in name only. The engine had considerable structural, aerodynamic, and turbine differences when compared to the earlier varients of the TF-30. Maximum turbine inlet temperatures were 300-500 degrees higher than the earlier engines.
The engine would produce an honest 25,100 lbs of thrust and I have run them in a test cell and even got a little more than that.
Considerable development work was accomplished to improve the engine's tolerance to inlet distortion and some of that work even translated to the JT8D-22 engine used on the Viggen.
Blackbird From , joined Dec 1969, posts, RR: Reply 9, posted (4 years 7 months 3 weeks 3 days 15 hours ago) and read 3173 times:
Broke,
If it could achieve turbine temps 300 to 500 degrees higher, I would assume it had a higher thrust to weight ratio and could fly at higher mach numbers too?
Blackbird
BTW: The TF-30's that powered the F-14 were conventional TF-30's right?
KC135TopBoom From United States of America, joined Jan 2005, 11704 posts, RR: 52 Reply 10, posted (4 years 7 months 3 weeks 3 days 9 hours ago) and read 3159 times:
Quoting Legs (Reply 7): Quoting KC135TopBoom (Reply 6):
carries a heavier weapons load and longer legs compared to the F-111C.
All true, but the G takes a slight top speed hit over the C model.
Not really, both the F-111C and F-111G have a max speed of Mach 2.2 (max wing sweep and clean configueration). The F-111C can sustain 2.2 speed for 30 minutes, while the F-111G can sustain 2.2 for 45 minutes (max wing sweep and clean configueration). But, why would you do that?
Thats the first Ive heard about the sustained top speed between the models. I would wager that you would run up against the airframe temp limits well before those times anyway.
Having said that, there is quite a few stories floating around of indicate speeds well in excess of Mach 2.2, some of them even claim to have flight data backup. Of course, it could just be pilots bragging and the rumour mill exaggerating as usual.
KC135TopBoom From United States of America, joined Jan 2005, 11704 posts, RR: 52 Reply 12, posted (4 years 7 months 3 weeks 1 day 9 hours ago) and read 3088 times:
Quoting Legs (Reply 11): Having said that, there is quite a few stories floating around of indicate speeds well in excess of Mach 2.2, some of them even claim to have flight data backup.
Actually, it is true, at least in the case of USAF 509th BW FB-111A, tail number 68-0282, and later became F-111G in the RAAF, tail number A8-282. In the late 1980s while still assigned to the 509th at Pease, she was assigned a hot run, which normally took the airplane over the Atlantic to a range SE of Cape Cod for a M2.2 run for 12 minutes. This is done with tanker support, over the range in AR Track 608, and is topped off prior to the run, The FB-111 is claean, no tanks or racks on the wings. Well, according to the data recoorder, she hit M2.5 for 6 of the scheduled 12 minutes, and exceeded the 12 minute run by 3 or 4 minutes. This split open the leading edge of the vertical tail, a section about 12" long about mid way up, peeling back some of the skin alng the sides of the vertical stab. Word is the crew never noticed until the Boom Operator told them of the damage on the post refueling, then they looked into the mirrors.
Nice! Any idea what altitude was/would have been used for the run?
I know the section that would have peeled off, although its usually the radome, glove, and wing leading edges that cop most of the damage from speed runs, everything else being equal.
EBJ1248650 From United States of America, joined Jun 2005, 1932 posts, RR: 2 Reply 14, posted (4 years 7 months 3 weeks 1 day 4 hours ago) and read 3071 times:
I did a search of the scramble web site and could find nothing regarding the -111 or -111 engines.
Quoting Broke (Reply 8): The P-100 series of the TF-30 were TF-30's in name only. The engine had considerable structural, aerodynamic, and turbine differences when compared to the earlier varients of the TF-30. Maximum turbine inlet temperatures were 300-500 degrees higher than the earlier engines.
The engine would produce an honest 25,100 lbs of thrust and I have run them in a test cell and even got a little more than that.
I presume this includes the P-107, P-108 and P-109? 25,000 thrust rating for all of them?
Broke From United States of America, joined Apr 2002, 1322 posts, RR: 4 Reply 15, posted (4 years 7 months 3 weeks 21 hours ago) and read 3047 times:
The TF-30-P100 engines operated in the same Mach number/air speed range as the earlier varients of the TF-30. It provided the F-111 with better take off and climb performance or it could be used to operate the airplane at higher take off weights.
I met an ex-F-111A pilot and he told me me that on the F-111A when they taxi'ed unto the runway, they would go to zone 5 on the A/B. If they weren't airborne within 30 minutes they would go back to the hangar.
While that is a humorous indication of the low power to weight ratio of the F-111A, the airplane still did not have exceptional take-off and climb performance at high gross weights.
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