F-14 low speed prowess vs Other Aircraft

[captain_dalan]

Regarding performance at SL, looking at the charts an average of 2 deg/sec is gained pr. 5,000 ft in altitude, thus a pretty good guess would be that at SL the F-14 featured an ITR of 23.5 deg/sec @ Mach ~0.45 and 6.5 G.

 

This would translate into a ITR of 24.5 deg/sec @ Mach 0.5 and 7 G at SL.

 

This is a pretty good estimate. It's actually 25deg/s at 300 knots and 7G :)

 

Now as for STR, the F-14 (all versions) features a higher STR than the F-15 between Mach 0.30 to 0.75, however the higher available thrust of the F-14B/D version ought to increase that interval, maybe from Mach 0.2 to 0.9, as well as the difference in max STR by perhaps 0.5 to 0.75 deg/sec. Which in practice means the F-14B/D probably holds a noticable advantage in both ITR and STR at all flying speeds up to Mach 0.9.

 

 

This is however a bit too much guesswork. Even an all around 10% increase of STR across the entire board would give any F-14 version that broad of an advantage over the F-15. No matter which engines you use on the Eagle, you can expect it perform better once you hit mach 0.74-0.76 ASL. don't even think about going to the mach 0.8-0.9 region, this where the Eagle outperforms everything i have ever seen as far as STR is at stake.

 

But if you are looking for a part of the envelope that the F-14 can use the most of its advantages against an F-15, then the lower you are the better. ASL, the F-14A caps at just over 18deg/s STR which over a degree higher then the PW100 engined F-15 and just about the same as PW220 engined ones. However the main advantage here is that the F-14A needs "only" 6g to pull that rate, while the F-15 will need anywhere from 8.6-9g, thus prohibiting the pilot from entering any sustained turning fight this low.

 

So yeah, can the F-14B "out turn" the F-15C ASL? Probably.... by half a degree or something, but that is not why you are better off low.

 

Then you have the other side of the spectrum. As you go up, first to 15000 and then 20000ft the planes literally level out, until at any altitude above angels 20, the eagle holds most of the advantages.

[turkeydriver]

Regarding performance at SL, looking at the charts an average of 2 deg/sec is gained pr. 5,000 ft in altitude, thus a pretty good guess would be that at SL the F-14 featured an ITR of 23.5 deg/sec @ Mach ~0.45 and 6.5 G.

 

This would translate into a ITR of 24.5 deg/sec @ Mach 0.5 and 7 G at SL.

 

Now as for STR, the F-14 (all versions) features a higher STR than the F-15 between Mach 0.30 to 0.75, however the higher available thrust of the F-14B/D version ought to increase that interval, maybe from Mach 0.2 to 0.9, as well as the difference in max STR by perhaps 0.5 to 0.75 deg/sec. Which in practice means the F-14B/D probably holds a noticable advantage in both ITR and STR at all flying speeds up to Mach 0.9.

 

Remember that we see the exact same happening with the F-15A vs F-15C, where the extra available thrust increased the max STR by 0.75 deg/sec, and same would naturally happen with the F-14A to B/C.

 

Note: This is using the F-14A charts as our baseline and disregarding the F-14B/D charts as they are without the maneuver devices operating, hence the Mach 0.3 - 0.75 STR figure base figure.

 

Maneuvering devices on auto/not functional does not refer to the glove vanes, it refers to the auto maneuver devices on the wings-flaps and slats. So the F-14B/D have graphs for auto/ not functional just as the F-14A does. The performance manuals were classified up until retirement and I do not know if they have actually been released or remain classified, so be careful digging around for that stuff unless you know its OK.

[Hummingbird]

Dalan,

 

I'm thinking that since the F-14A holds an advantage in STR from M 0.3 to 0.75, then the F-14B/C ought to hold an advantage at an even longer interval (my guess was M 0.2-0.9), and that thanks to the 15,000 lbs or so extra thrust provided by the GE engines.

 

For example you see a 0.75 deg/sec increase in max STR from the F-15A to the C with a much smaller increase in thrust. Thus would it not be reasonable to expect at least a 1 deg/sec increase in STR from the F-14A to the B/D model?

 

This is assuming that the F-14B/D holds a similar advantage over the F-15C in ITR as the F-14A holds one over the F-15A, i.e. ~1 G across the board.

[turkeydriver]

Dalan,

 

I'm thinking that since the F-14A holds an advantage in STR from M 0.3 to 0.75, then the F-14B/C ought to hold an advantage at an even longer interval (my guess was M 0.2-0.9), and that thanks to the 15,000 lbs or so extra thrust provided by the GE engines.

 

For example you see a 0.75 deg/sec increase in max STR from the F-15A to the C with a much smaller increase in thrust. Thus would it not be reasonable to expect at least a 1 deg/sec increase in STR from the F-14A to the B/D model?

 

This is assuming that the F-14B/D holds a similar advantage over the F-15C in ITR as the F-14A holds one over the F-15A, i.e. ~1 G across the board.

 

We need to see the power curves for the engines- FYI the TF-30 engine that we call a 20k lb thrust motor actually makes near 30k lb/thrust at sea level at mach 0.9, and the F-14B/D F-110 as a 27k lb/thrust motor makes more like 34k in that same regime. These power curves will be important in identifying the best speeds to fight these aircraft at.

[Hummingbird]

Maneuvering devices on auto/not functional does not refer to the glove vanes, it refers to the auto maneuver devices on the wings-flaps and slats. So the F-14B/D have graphs for auto/ not functional just as the F-14A does. The performance manuals were classified up until retirement and I do not know if they have actually been released or remain classified, so be careful digging around for that stuff unless you know its OK.

 

I know it doesn't refer to the glove vanes, but the maneuver slats & flaps as you describe.

 

Hence why I am of the opinion that for ITR we are to use the F-14A graphs with the maneuvering devices on auto. What I'm saying here is that the F-14B/C's ITR must be pretty much identical to the F-14A's when the maneuvering devices are in operation, thus the F-14B/C's ITR graph with maneuvering devices in operation will look the same as the F-14A's.

 

Hence for STR we need to look at the F-14A graph and calculate what a 15,000 lbf increase in thrust would constitute in terms of increase in the STR across the board, which such a massive increase in thrust no doubt will affect.

[captain_dalan]

Dalan,

 

I'm thinking that since the F-14A holds an advantage in STR from M 0.3 to 0.75, then the F-14B/C ought to hold an advantage at an even longer interval (my guess was M 0.2-0.9), and that thanks to the 15,000 lbs or so extra thrust provided by the GE engines.

 

For example you see a 0.75 deg/sec increase in max STR from the F-15A to the C with a much smaller increase in thrust. Thus would it not be reasonable to expect at least a 1 deg/sec increase in STR from the F-14A to the B/D model?

 

This is assuming that the F-14B/D holds a similar advantage over the F-15C in ITR as the F-14A holds one over the F-15A, i.e. ~1 G across the board.

But the F-14A doesn't hold an STR advantage from 0.3-0.75mach, rather from 0.4-0.7 or are we looking at different charts? :huh:

 

EDIT:

 

Hence for STR we need to look at the F-14A graph and calculate what a 15,000 lbf increase in thrust would constitute in terms of increase the STR across the board, which such a massive increase in thrust no doubt will affect.

The increase in thrust might not be as great as you'd expect. The PW TF30's were very good down low in the high subsonic-transonic region :)

Edited March 17, 2015 by captain_dalan

[turkeydriver]

I know it doesn't refer to the glove vanes, but the maneuver slats & flaps as you describe.

 

Hence why I am of the opinion that for ITR we are to use the F-14A graphs with the maneuvering devices on auto. What I'm saying here is that the F-14B/C's ITR must be pretty much identical to the F-14A's when the maneuvering devices are in operation.

 

Thus for STR we need to look at the F-14A graph and calculate what a 15,000 lbf increase in thrust would constitute in terms of increase the STR across the board, which such a massive increase in thrust no doubt will affect.

 

AH ok F-14B/D BTW, not B/C. We would need power graphs of the motors though correct, I don't think its that easy to just 15k of thrust throughout the envelope, the response isn't automatic like AFAIK, but I'm no engineer.....yet:D

[Hummingbird]

AH ok F-14B/D BTW, not B/C. We would need power graphs of the motors though correct, I don't think its that easy to just 15k of thrust throughout the envelope, the response isn't automatic like AFAIK, but I'm no engineer.....yet:D

 

B/D correct, typo by me :D

[Hummingbird]

But the F-14A doesn't hold an STR advantage from 0.3-0.75mach, rather from 0.4-0.7 or are we looking at different charts? :huh:

 

I am looking at your chart :)

 

 

 

Advantage starts at 200 kts (230 mph) which translates to Mach 0.3 :)

 

EDIT:

 

The increase in thrust might not be as great as you'd expect. The PW TF30's were very good down low in the high subsonic-transonic region :)

 

 

Good point, but seeing as our comparison charts are at 10,000-15,000 ft I believe my point holds :)

[Hummingbird]

EDIT: I was wrong about the mach numbers, by mistake I used SL values doh!

 

It's Mach 0.35 to 0.75 for the F-14A over the F-15A

[captain_dalan]

I am looking at your chart :)

 

 

 

Advantage starts at 200 kts (230 mph) which translates to Mach 0.3 :)

 

 

 

 

Good point, but seeing as our comparison charts are at 10,000-15,000 ft I believe my point holds :)

Ah, but look at the bottom of the chart. It's CAS (calibrated air speed). 200 knots CAS is about 250 knots true air speed, which is then again 0.40 mach :)

 

EDIT:

 

EDIT: I was wrong about the mach numbers, by mistake I used SL values doh!

 

It's Mach 0.35 to 0.75 for the F-14A over the F-15A

 

Check the above. You need to converted calibrated or indicated air speed to true airspeed before calculating the mach. Note that the F-15 charts are all given in TM numbers, except for the one provided by lunaticfringe that gave us the ITR :)

Edited March 17, 2015 by captain_dalan

[Hummingbird]

Ah, but look at the bottom of the chart. It's CAS (calibrated air speed). 200 knots CAS is about 250 knots true air speed, which is then again 0.40 mach :)

 

Yeah I noticed my mistake :doh:

 

Here's the F-14A v F-15A chart you provided:

 

It shows the advantage in STR from Mach ~0.35 to ~0.75 :)

 

Now ofcourse this is at 10,000 ft meaning we're moving further inside the F-14's domain. If we go upwards of 20 kft we will see the trend starting to shift as you point out.

[captain_dalan]

That is the F-14B at 10kft overlaid on the F-15A. So compared to the F-14A you gained around 10-15 knots on either side. Again, not that much dramatic of an improvement :)

[Hummingbird]

That is the F-14B at 10kft overlaid on the F-15A. So compared to the F-14A you gained around 10-15 knots on either side. Again, not that much dramatic of an improvement :)

 

Oh alright, now I'm confused :P

 

So the chart I just posted is based on the F-14B/D charts? In that case it's without the maneuvering devices operating though, which I'd assume would affect the STR quite noticably :)

[captain_dalan]

Oh alright, now I'm confused :P

 

So the chart I just posted is based on the F-14B/D charts? In that case it's without the maneuvering devices operating though, which I'd assume would affect the STR quite noticably :)

Actually it takes the maneuvering devices into account, and those don't operate once past 55 degrees wing sweep anyway, so the benefit is only in the low-mid subsonic region :smilewink:

[Hummingbird]

Actually it takes the maneuvering devices into account, and those don't operate once past 55 degrees wing sweep anyway, so the benefit is only in the low-mid subsonic region :smilewink:

 

How did you take those into account without a chart with them in operation? :) (or perhaps Lunaticfringe provided those in PM? :) )

 

PS: Is there a chance you could do a F-14B/D vs F-15C ITR & STR chart like the F-14A vs F-15A one? :)

Edited March 17, 2015 by Hummingbird

[captain_dalan]

1.How did you take those into account? :)

 

2.PS: Is there a chance you could do a F-14B/D vs F-15C ITR & STR chart like the F-14A vs F-15A one? :)

1. Estimation based on the one's without and some help

 

2. Probably not, it would require too much work and at this point, i don't think it really serves a purpose.

[Hummingbird]

1. Estimation based on the one's without and some help

 

Alright, I am a bit surprised that your estimation only shows a 10-15 kt increase to either side of the envelope considering the massive increase in thrust that the GE engines provided at 15,000 ft.

 

I would expect a result more similar to the F-15A vs F-15C which itself experienced a STR increase of 0.75 deg/sec at that altitude with a lower thrust increase.

 

2. Probably not, it would require too much work and at this point, i don't think it really serves a purpose.

 

Bummer :( Think it would be quite useful with such a chart to be honest :)

[GGTharos]

Makes you wonder how correct those thrust figures are, or at least what the context is for the maximum thrust rating.

The TF30 installed in the F-111 was rated at 25000lbs, the one in the F-14 at 20900.

The F-14B weighs in 1600lbs heavier than the F-14A.

 

 

One of the absolutely most important things gained with the new engines was not maneuverability: It was safety (engine failure on takeoff), ability to take off from the carrier with no afterburner, and also the cat gained 100nm or more in range for certain mission profiles.

Edited March 17, 2015 by GGTharos

[captain_dalan]

Alright, I am a bit surprised that your estimation only shows a 10-15 kt increase to either side of the envelope considering the massive increase in thrust that the GE engines provided at 15,000 ft.

 

I would expect a result more similar to the F-15A vs F-15C which itself experienced a STR increase of 0.75 deg/sec at that altitude with a lower thrust increase.

 

The peak STR would still increase, probably in the 0.5-1.0 deg/s range, but not across the entire board, no.

 

Makes you wonder how correct those thrust figures are, or at least what the context is for the maximum thrust rating.

The TF30 installed in the F-111 was rated at 25000lbs, the one in the F-14 at 20900.

 

 

One of the absolutely most important things gained with the new engines was not maneuverability: It was safety (engine failure on takeoff), ability to take off from the carrier with no afterburner, and also the cat gained 100nm or more in range for certain mission profiles.

Especially the ability to climb to 35000ft without afterburner use. That alone was a huge operational benefit. Not to mention acceleration, climb rate....

 

EDIT: the installed thrust value for the TF30's is actually more in the 17-18000pds range, once all the variables are accounted for.

[GGTharos]

Well yeah, static thrust rating on the ground rarely means much - once installed you usually lose 80% of that until you get going faster.

[Hummingbird]

The peak STR would still increase, probably in the 0.5-1.0 deg/s range, but not across the entire board, no.

 

Not across the board obviously, but it should raise the roof of the doghouse so to speak, and by doing so should increase the size of the envelope within which the F-14 holds and STR advantage :)

 

In short if the F-14A holds an advantage from 0.4 to 0.75 then I'd expect the F-14B/D to hold one from at least 0.3-0.8 at 15,000 ft.

[turkeydriver]

Makes you wonder how correct those thrust figures are, or at least what the context is for the maximum thrust rating.

The TF30 installed in the F-111 was rated at 25000lbs, the one in the F-14 at 20900.

The F-14B weighs in 1600lbs heavier than the F-14A.

 

 

One of the absolutely most important things gained with the new engines was not maneuverability: It was safety (engine failure on takeoff), ability to take off from the carrier with no afterburner, and also the cat gained 100nm or more in range for certain mission profiles.

 

That was a different version of the TF-30 for the F-111-don't know what the differences were other than possibly the accessories attached differently....just remember the TF-30 can hits 30000lbs of thrust installed in the F-14A at Mach0.9 at sea level ( supersonic fly-bys=no sweat:D). The engines could be slammed from full AB to idle and back without coughing and dying, and this was important. The no take offs in AB were allowed on the carrier but necessary as the JBDs couldn't take 2 F-110s blasting in full AB and ashore, if one motor did fail on take off, the rudder cannot compensate for the thrust, so its a no win scenario. this is why all F-14B/D demos wait until clearing the mainmounts before lighting AB.

I'm sure all of you know, the top speed is also limited as Mach 1.8 for F-14B/D because the rudder cannot compensate at high speed if a motor quits.

[captain_dalan]

I'm sure all of you know, the top speed is also limited as Mach 1.8 for F-14B/D because the rudder cannot compensate at high speed if a motor quits.

It wasn't just because of the inlet scheduling?

 

Not across the board obviously, but it should raise the roof of the doghouse so to speak, and by doing so should increase the size of the envelope within which the F-14 holds and STR advantage

 

It does, just not by that much :)

[BlackLion213]

That was a different version of the TF-30 for the F-111-don't know what the differences were other than possibly the accessories attached differently....just remember the TF-30 can hits 30000lbs of thrust installed in the F-14A at Mach0.9 at sea level ( supersonic fly-bys=no sweat:D). The engines could be slammed from full AB to idle and back without coughing and dying, and this was important. The no take offs in AB were allowed on the carrier but necessary as the JBDs couldn't take 2 F-110s blasting in full AB and ashore, if one motor did fail on take off, the rudder cannot compensate for the thrust, so its a no win scenario. this is why all F-14B/D demos wait until clearing the mainmounts before lighting AB.

I'm sure all of you know, the top speed is also limited as Mach 1.8 for F-14B/D because the rudder cannot compensate at high speed if a motor quits.

 

It's true, the TF30 makes great power down low, even better with speed. That said, the biggest deficit is between 15,000 and 25,000, the TF30's thrust deteriorates more rapidly with altitude than most other engines. Since the hard-deck for ACM is usually set at 10,000', most Tomcat pilots didn't get to fight at their preferred altitude. The F110 makes excellent thrust in the middle and high altitudes and that offered a HUGE increase in practical performance. With the TF30, the ITR is quite good, but after the first 120-180 deg of the turn the Tomcat starts to bleed airspeed and AOA rises rapidly. The F110 powered Tomcats can sustain high-G turns for much longer. In the F-14A, the solution is to descend while you turn, though this isn't ideal for all situations.

 

The reliability of the F110 was the biggest plus, but the thrust benefits are also quite important. If you fly the F-14A at full afterburner and below 10,000', you might not think there is anything wrong with it (excluding slow spool up and risk of stalls with rapid throttle movement). But fly a loaded F-14A at 30,000' and you'll be tempted to "tap" burner a lot. At altitude and military power, by all accounts, it certainly feels underpowered. By contrast, the F110 Tomcats love altitude and require a lot less throttle to climb, maintain airspeed, or accelerate. The difference in power "feels" bigger during normal operations than the numbers might suggest.

 

BTW, the installed thrust (meaning in the airframe @ 0 kts) is always about 15-20% lower than static thrust.

TF30 installed-17,077; static - 20900

F110 installed - 23000; static - 27550

 

The F-111F had the 25,000 version of the TF30. It was a different subvariant, not sure what had changed. The early F-111 had a TF30 rated at 18,000 lbs static. The Navy never considered it because their highest priority with a new powerplant was improving stall margin and no TF30 variant really did that.

 

I LOVE the F-14A (looking forward to it a bit more than the F-14B) and I am very happy the LNS is including it with the F-14B. That said, if you want to fight another 4th generation fighter, the F110 engine will make your job much easier.

 

Best,

 

Nick