F-104 E-M diagrams?

[SuperKermit]

Does anybody have access to E-M diagrams for the Zipper?

Everywhere it is stated that its turn performance was so bad, but if you compare its corner speed and corresponding load factor with that of an F-4 it does not seem so bad at all. I guess the S-version should be even better.

That topic is discussed here for instance, but I would like to compare some data.

 

Edited August 26, 2023 by ChrisKermit

[Bremspropeller]

I remember an extract that Andy Bush once posted from the 104G manual on the keypublishing forums that had the 104G at 50% fuel, two tip winders and 5000ft (IIRC) at just about 7g sustained around 420-450KIAS. Think hard wing F-4 with possibly a touch more Ps at higher airspeeds. But that's just top of my mind and in a nutshell.

 

The M1.8 flap limit is a typo. It's actually 0.85, though one canadian CF once had the T/O flaps out till 1.3 on a Mach-run, had the pilot wonder about the hesitant accel, see the flaps are out, retract them and carry on.

 

104G Systems and limitations:

http://www.916-starfighter.de/F-104_Bad Ass Airplane.htm

Edited August 26, 2023 by Bremspropeller

[SuperKermit]

vor 2 Stunden schrieb Bremspropeller:

I remember an extract that Andy Bush once posted from the 104G manual on the keypublishing forums that had the 104G at 50% fuel, two tip winders and 5000ft (IIRC) at just about 7g sustained around 420-450KIAS. Think hard wing F-4 with possibly a touch more Ps at higher airspeeds. But that's just top of my mind and in a nutshell.

Here is the E-M diagram for the F-4E (slatted or not idk) - 7g sustained at M0.8 (515kt). That would give the edge to the 104.

 

 

Edited August 26, 2023 by ChrisKermit

[Bremspropeller]

FWIW this contains a couple of Ps curves for the 104G and 104C in different configs and environmental conditions:

http://www.916-starfighter.de/SURE7_InterceptProfileOptimization.pdf

[Bremspropeller]

Also, for the 104C, check out Annex G of this one:

https://apps.dtic.mil/sti/citations/AD0372500

[Snappy]

6 hours ago, Bremspropeller said:

I remember an extract that Andy Bush once posted from the 104G manual on the keypublishing forums that had the 104G at 50% fuel, two tip winders and 5000ft (IIRC) at just about 7g sustained around 420-450KIAS. Think hard wing F-4 with possibly a touch more Ps at higher airspeeds. But that's just top of my mind and in a nutshell.

 

The M1.8 flap limit is a typo. It's actually 0.85, though one canadian CF once had the T/O flaps out till 1.3 on a Mach-run, had the pilot wonder about the hesitant accel, see the flaps are out, retract them and carry on.

 

104G Systems and limitations:

http://www.916-starfighter.de/F-104_Bad Ass Airplane.htm

 

Some more interesting stories&information from Andy Bush,including it’s capabilities in flat scissors vs . the Topgun F-5s

https://combatsim.com/review.php?id=5

Plus this amusing story where he and his wingman outsmarted a duo of F-15 and gunned them.There he also mentions the ability to sustain 7G at around 400kts with the flaps .

https://theaviationgeekclub.com/starfighter-4-eagle-0-that-time-two-f-104s-scored-four-simulated-kills-against-an-f-15b-in-a-single-training-mission/amp/

Edited August 26, 2023 by Snappy

[TLTeo]

I have a 1996 F-104S manual (so no posting stuff from it because 1.16, but it's easily found online) which shows up to 7.33 G at 500 KIAS up to 30000 ft, so that's roughly Mach 0.75 to 0.8. That is just the structural limit so I'm not sure whether it's with combat flaps extended or not (but I don't see why not - that speed is within the flap envelope). It's similar to the OP's post, except for the larger envelope overall due to the 7.3 G limit vs only 6 of the F-104A (which I think is what the first diagram is). The same manual states that combat flaps give one extra G worth of turning performance across the envelope, which will definitely come in handy.

Comparing it to an F-4 E/M diagram I imagine the F-104 will actually be competitive at Mach ~0.75 and above at low weight, but trash tier below it.

edit: regarding the flaps, the same manual states that they can be safely kept out up to Mach 0.85 or 520 KIAS, whichever comes first, but extending or retracting is only allowed below 450 KIAS or Mach 0.7 - ish.

Edited August 26, 2023 by TLTeo

[Bremspropeller]

19 minutes ago, TLTeo said:

edit: regarding the flaps, the same manual states that they can be safely kept out up to Mach 0.85 or 520 KIAS, whichever comes first, but extending or retracting is only allowed below 450 KIAS or Mach 0.7 - ish.

I have a  -S manual which states the following (Section 5-5):

During extension: 450KIAS or M0.85 (no Mach limit if 330KIAS isn't exceeded)

Out and retracting: 520KIAS or M0.85 (no Mach limit if 360KIAS isn't exceeded)

Edited August 26, 2023 by Bremspropeller

[TLTeo]

Ah yes that sounds about right, I was quoting from memory

Edited August 26, 2023 by TLTeo

[SuperKermit]

vor 6 Stunden schrieb Bremspropeller:

Also, for the 104C, check out Annex G of this one:

https://apps.dtic.mil/sti/citations/AD0372500

These are amazing documents! I especially love the included drawings in the first one, relating to the „Zeitgeist“ of that time! Big thanks for that!

The different depictions of flight performance data however make comparisons quite difficult..

Edited August 26, 2023 by ChrisKermit

[SuperKermit]

vor 2 Stunden schrieb TLTeo:

Comparing it to an F-4 E/M diagram I imagine the F-104 will actually be competitive at Mach ~0.75 and above at low weight, but trash tier below it.

That is also my interpretation of the data I have at hand!

Edited August 26, 2023 by ChrisKermit

[Smyth]

10 hours ago, Bremspropeller said:

I remember an extract that Andy Bush once posted from the 104G manual on the keypublishing forums that had the 104G at 50% fuel, two tip winders and 5000ft (IIRC) at just about 7g sustained around 420-450KIAS. Think hard wing F-4 with possibly a touch more Ps at higher airspeeds. But that's just top of my mind and in a nutshell.

I'm afraid that can't be correct -- Vn diagram suggests maximum lift of around 5g without flaps at that speed. A rough calculation of maximum lift with takeoff flaps and wingtip sidewinders (from stall speeds in TO 1F-104G-1, which should scale up relatively well since F104 "stall" is actually a stick pusher at a fixed aoa) gives CLmax of 0.96, which means 7g still cannot be reached even instantaneously until about ~500kias.

Obviously if you have a different primary source I will review my numbers.

8 hours ago, ChrisKermit said:

Here is the E-M diagram for the F-4E (slatted or not idk) - 7g sustained at M0.8 (515kt). That would give the edge to the 104.

FWIW that is a slatted F-4E with TISEO (not specified in the title but you can tell from the weight).

For the reason I explained above, the best possible case is that an F104G could match the Phantom if it sustains its maximum lift at M0.85. However I am highly skeptical because the Starfighter has less t:w, lower wing aspect ratio, and higher wing loading than the F4E.

To back that up, the TAC Mission 857 report (which @Bremspropeller linked above) shows 5g performance contours for the F104C and F4C at sea level. From where they intersect 0 Ps, we can tell the F4C is sustaining 5G at just under M0.6, while the F104C is sustaining 5G at just over M0.6. This is for the light 104C and the hard-wing F4C. Between a slatted F4E and the weight-crept F104G there is no chance (in my opinion).

For context, as I have said before and will say again, the subsonic sustained turn performance of the F4 is really exceptional among contemporary M2.0 capable fighters. For the F104 to come anywhere close to a Phantom is impressive enough.

Overall the 60s USAF assessments were correct regarding how the F104 needs to be flown. It will rely on subsonic/transonic climb rate, where it trashes ALL F4, Mig21, Mig23, Mirage III/F1, and even the F14A. Combined with semi-decent turning energy retention at >M0.8, that makes loops and climbing spirals very viable and dangerous. In that sense the F104 can absolutely dogfight, just not in the horizontal plane.

Regardless, I am trying to derive an approximate doghouse plot for the F104C from the TAC report. That is not straightforward due to the way the data is presented, but I have been unable to find subsonic turn data for the Starfighter anywhere else so it's worth a shot.

[Bremspropeller]

48 minutes ago, Smyth said:

A rough calculation of maximum lift with takeoff flaps and wingtip sidewinders (from stall speeds in TO 1F-104G-1, which should scale up relatively well since F104 "stall" is actually a stick pusher at a fixed aoa) gives CLmax of 0.96, which means 7g still cannot be reached even instantaneously until about ~500kias.

The 104S manual I have states on 1-47 that

NOTE:

When flaps are lowered to TAKEOFF position, the angle at which angle-of-attack sensing vane energizes the stick shaker or the kicker is automatically increased, thereby permitting aircraft maneuvering to a higher angle of attack than when flaps UP.

 

48 minutes ago, Smyth said:

For the reason I explained above, the best possible case is that an F104G could match the Phantom if it sustains its maximum lift at M0.85. However I am highly skeptical because the Starfighter has less t:w, lower wing aspect ratio, and higher wing loading than the F4E.

The 104's got a better subsonic L/D, though. Something like 9.2 for the 104 and 8.6 for the F-4, plus the fuselage is creating a good deal of lift on the 104.

https://www.hq.nasa.gov/pao/History/SP-468/app-a3.htm

 

48 minutes ago, Smyth said:

Regardless, I am trying to derive an approximate doghouse plot for the F104C from the TAC report. That is not straightforward due to the way the data is presented, but I have been unable to find subsonic turn data for the Starfighter anywhere else so it's worth a shot.

Looking forward to reading your analysis!

Edited August 26, 2023 by Bremspropeller

[SuperKermit]

Great input from everyone here! It is a pleasure to follow that constructive discussion! I really appreciate that! Many thanks 

[Smyth]

This is going to be a long post because I need to explain the basis for the chart I made, so that no one is confused where it actually comes from. Normally I only trust direct turn-rate or time-to-turn charts from official documents, however that doesn't seem to exist for the F104 anywhere. Even the sustained-G charts in the F104 manuals, which could be converted to turn rate, start at Mach 1 and 35000ft.

There is a good reason for that, as neither the USAF nor Lockheed wanted to encourage F104 pilots to make sustained turns while subsonic. However this is a flight sim forum and lets be honest -- if/when the module releases most of us will immediately drop the takeoff flaps and pull to the aoa limiter to see what the airframe can really do. At least once anyway.

Sadly the TAC report for the F104C I mentioned before didn't work out. The Ps vs Mach curves there cannot be converted into sustained turn at a fixed altitude because they don't intersect Ps=0 below 5G. Without multiple data points for Ps=0 I can't even try to build a trend for sustained turn vs. airspeed. In the picture below it looks tempting to extend the lines down to zero, but after some more investigation that won't work, so we are back to square 1.

The good news is that @Bremspropeller pointed me towards another possible source for F104 subsonic maneuverability. Lockheed had a series of lectures for F104 pilots called "Project SURE", and one of them includes a plot of constant-G contours vs Mach and Altitude. With that I can record the intersections of a constant-G curve with a fixed altitude, and fit a trend to those points to estimate what a sustained-G curve would look like at a constant altitude. From inspection of charts for similar aircraft (Mig-21, F-4), they are usually nearly linear up to about M0.85 where transonic drag spikes. Conveniently the flap limit for the F104G is M0.85 anyway, so I don't need to be perfectly accurate above that point.

Mig21 as an example to visualize what I am trying to construct:

Here is the result:

Real aerospace engineers may be horrified at this point, but the fit was good enough that I decided to continue.

With the hard part done, I can enter the results into a spreadsheet I have been working on to scale normal acceleration for gross weight, and interpolate to a constant altitude for comparison with other aircraft.

Filling in the instantaneous turn rate presented a small problem as well, because the V-n diagrams I would normally use (like what the OP posted) are for flaps raised and don't specify an exact weight. Fortunately there is a stall speed chart for different conditions (flaps up/down, and different stores configurations) at known weights in the F104G manual which I can use to calculate Cl_max with takeoff flaps. Because the F104 has an aoa limiter, that Cl_max should scale well to higher speeds. A sanity check against the V-n diagram shows this is a reasonable assumption.

Here is the result. To be exact it is only the shell of a doghouse plot and not really an E-M diagram, and the data basis is pretty sketchy, but I think this is better than nothing.

The reason for the 1000m altitude is to enable comparison with other cold war fighters more easily, which I will add soon.

 

[TLTeo]

Looks about right, and consistent with the statement that flaps give one extra G worth of turning performance. ~14 deg/s sustained and ~16 instantaneous is also consistent with the claims that it wasn't an amazing dogfighter, but it wasn't as bad as it's made out to be either.

Am I misunderstanding your chart, or does it look like below Mach 0.7 you actually have so few Gs available without flaps that sustained G is actually lower than the max G available?

[Smyth]

(Edited 9/1): Shortly after I posted this, @IvanK came through with some original EM diagrams for the F104G. Please see his post later in the thread.

 On the plus side, it turns out my sketchy linear fit got within 4% which is about as good as I could have hoped for. The conclusions remain the same, but I've updated the graphic below with the real data.

For a comparison to other cold war fighters, I've taken a graphic I was working on to compare official data for the F4E and Mig-23ML with existing 70s jets in DCS and replaced the F5E with the F104. Hopefully the format makes some sense.

The result is pretty much as expected, but it's nice to have a direct comparison instead of trying to eyeball charts in different formats, at different weight and altitude.

F-4E is just better at anything in the horizontal, but it's a Phantom after all (I will not shut up about F4 maneuverability). Against the Soviet fighters, an F-104 can technically match their sustained turn rate, but its extremely restrictive instant turn envelope would make that very difficult to use. Overall the F104G is the one opponent where a pre-MLD Flogger might want to take a subsonic fight, however the Starfighter still destroys it in subsonic climb rate and acceleration so even then maybe not.

The drastic drop-off in turn performance with the flaps retracted at M0.85 is also going to be a major issue. How much of an issue depends on how flap damage is modeled. There is a NASA document (TN D-6943) investigating F104 handling with the flaps deployed up to M0.94, and anecdotal evidence of an F104 pilot accidentally leaving takeoff flaps extended while supersonic without severe consequences. Ideally Aerges finds a compromise that encourages players to fly realistically, without imposing an arbitrary and non-physical limit.

On 8/27/2023 at 6:18 PM, TLTeo said:

Am I misunderstanding your chart, or does it look like below Mach 0.7 you actually have so few Gs available without flaps that sustained G is actually lower than the max G available?

Not exactly, if I understand your question correctly. That sustained turn is only for the flaps deployed below M0.85. Without flaps the sustained turn will be below the maximum G for a while longer, but I don't have any information available to extend that dotted line below M0.85.

Edited September 2, 2023 by Smyth
Updating with IRL manual numbers

[TLTeo]

Aaah that makes sense. Still it's a bit amusing that at low speeds having flaps down is such an improvement that sustained turn is better than instantaneous turn with flaps up.

[VZ_342]

Maybe everyone has got the "dash 1" manual already, but here it is.... (dated 1960)

[SuperKermit]

vor 4 Stunden schrieb Smyth:

F-4E is just better at anything in the horizontal, but it's a Phantom after all (I will not shut up about F4 maneuverability)

The F-4s maneuverability is impressive indeed! But the F-4 numbers in your charts seem to be a but higher than the ones in the E-M diagram I posted above. How would you explain that? Just the different loadout?

BTW, that’s impressive work @Smyth!

[Smyth]

7 minutes ago, ChrisKermit said:

The F-4s maneuverability is impressive indeed! But the F-4 numbers in your charts seem to be a but higher than the ones in the E-M diagram I posted above. How would you explain that? Just the different loadout?

BTW, that’s impressive work @Smyth!

Thank you. I was very curious about this topic, so I'm glad the result is interesting to others.

That EM diagram for the F-4E is supposedly from a document compiled by Northrop, so I would take it with a grain of salt. I don't think they were exactly lying, but they were definitely not motivated to make generous assumptions for the F-4E (to put it nicely), at a time when the USAF was giving out used Phantoms like candy and that made the F-20 a bit of a hard sell. Sustained turn looks right for the slightly different altitude and weight, but comparing to the V-n diagram in TO 1F-4E-1 there is no way that instant turn line reaches the 30 unit aoa operational limit. Possibly they used the 25 unit recommendation Phantom pilots were trained to follow.

I have more to say on the subject but I will save my Phantom cheerleading for a different thread. Just rest assured that I have tried hard to leave my bias out of these charts.

[Bremspropeller]

One thing tabou the flap-limits:

If the airspeed is below 330/360KIAS, there's actually no Mach limit for the flaps in T/O at all. Hence, especially at high altitude, they can be used in wild abandon.

@Smyth thanks a lot for your great work!

Edited August 28, 2023 by Bremspropeller

[SuperKermit]

vor 56 Minuten schrieb Smyth:

Just rest assured that I have tried hard to leave my bias out of these charts.

Don’t get me wrong, I absolutely believe that you are approaching that matter neutrally. I just find it quite interesting by how much even “official” documents differ sometimes in their data. 

vor 58 Minuten schrieb Smyth:

I have more to say on the subject but I will save my Phantom cheerleading for a different thread.

Looking forward to that! The F104 and F4 are both equally exciting IMHO!

[SuperKermit]

vor 38 Minuten schrieb Bremspropeller:

Hence, especially at high altitude, they can be used in wild abandon.

That would be roughly over 25k ft when M0.85 starts to become <360 kts. 

Edited August 28, 2023 by ChrisKermit

[SuperKermit]

vor 6 Stunden schrieb Smyth:

however the Starfighter still destroys it in subsonic climb rate and acceleration so even then maybe not.

How would you judge the 104s vertical capabilities vs the other fighters?