How to win at BFM in the Mighty F-4E Phantom

[=475FG= Dawger]

20 hours ago, Dragon1-1 said:

In most jets, you just have to keep your feet on the floor.

For normal (1 G) maneuver this is kinda sorta true but not really. The yaw displacement isn't very noticeable but it is still happening

 

It isn't true at all when maneuvering above 1 G acceleration.

 

20 hours ago, Dragon1-1 said:

 Your goal is to be wings level when you pickle, so no rudder input should be needed.

 

Wings level at the pickle may or may not mean ailerons/spoilerons neutral. If they aren't in trail, there will be yaw displacement requiring rudder correction.

[TotenDead]

I have a question that's somewhat related to bfm performance of the phantom. At what angle of Attack does a slatted phantom stall?

 

Just for example, here's the graph for the pre-slatted version, you can see that the aircraft stalls at around 23 degrees of aoa.

 

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So, slats should've improved the alpha capability of the aircraft. But how much? As far as I know, manuals use "units" which is, eh, super helpful. Perhaps someone knows numbers in some proper measurements? 

[Super Grover]

Sadly, there's no simple answer to this. First of all, with all the information I have, I wouldn't call the linked picture a reliable source. Then, the question is what alpha are you interested in - is it wing or fuselage (different F-4 sources use different references for that)? Then there's that constant issue of the conversion between the AoA in units and degrees - and this is probably the most challenging question we had to answer to properly use the resources when working on the FM of the F-4E. Finally, there are very significant differences between wind tunnel data and flight tests, and the in-flight calibration of the production AoA measurements was probably one of the issues. Finally, the problem is the definition of the stall point and how the stall is approached, which significantly impacts how the aircraft behaves. It was easier to test and collect the point when the aircraft departed.

Back for a moment to the attached plot - according to McDonnell, 1G departures for the base wing F-4E could happen as low as at 19° of wing AoA - so lower than what is presented in that graphics.

And after this too long introduction , when I drew all the uncertainties and how one should take all those numbers with a grain of salt, I can write that the slatted wing stalls/departs around 3°+ later than the non-slatted wing.

Edited May 26 by Super Grover

[TotenDead]

В 27.05.2025 в 01:23, Super Grover сказал:

Sadly, there's no simple answer to this. First of all, with all the information I have, I wouldn't call the linked picture a reliable source. Then, the question is what alpha are you interested in - is it wing or fuselage (different F-4 sources use different references for that)? Then there's that constant issue of the conversion between the AoA in units and degrees - and this is probably the most challenging question we had to answer to properly use the resources when working on the FM of the F-4E. Finally, there are very significant differences between wind tunnel data and flight tests, and the in-flight calibration of the production AoA measurements was probably one of the issues. Finally, the problem is the definition of the stall point and how the stall is approached, which significantly impacts how the aircraft behaves. It was easier to test and collect the point when the aircraft departed.

Back for a moment to the attached plot - according to McDonnell, 1G departures for the base wing F-4E could happen as low as at 19° of wing AoA - so lower than what is presented in that graphics.

And after this too long introduction , when I drew all the uncertainties and how one should take all those numbers with a grain of salt, I can write that the slatted wing stalls/departs around 3°+ later than the non-slatted wing.

Thank you for the info! 

The picture I used is from this document 
 

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Also attached it to the post just in case


The analysis is generally focused on the F-4J, however:
 

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Hopefully, the paper will be useful


When it comes to the AOA, it would be interesting to see some true AoA numbers, I'd assume that there should be a formula to recalculate local aoa (or even units) to the true one. Just as an example - a formula for local-to-true aoa recalculation from MiG-23ML FM
 

Спойлер

Speaking of 19 degrees departures, perhaps those happened when a pilot missed to see that the aircraft is flying with some degree of yaw?

The 3 degrees difference between hard and slatted wings is an interesting piece of information. It would be great if the hard wing version aoa could be determined at least for some best case scenario

a101646 (1).pdf

[Squiffy]

Been away for a while, but recently got the F-4 and am now getting acquainted. I can emphasize the tips here about fighting in the vertical. The Tactical Egg was a great concept to mention. I remember a book, years ago in high school, that analyzed the dog fighting tactics that won success in Vietnam. (Air war over Vietnam? A coffee table book with great illustrations). The rolling scissors and vertical rolling scissors were the name of the game. Both ways of integrating the vertical into the fight to take advantage of the thrust advantage, and a-stall disadvantage of the Fishbed. Farmers were even more challenging in a gunfight. 

I can say for a fact that the SFM has some serious flaws. Namely, the table entries for airspeed, alpha, theta and so on... as you approach Mach = 0. The numbers never go to zero, which for lift is impossible. At Mach = 0, Lift = 0. I confirmed this with my brother who is an aerospace engineer. And yes, he is a spacecraft and orbital mechanics specialist, so the UFO and Sputnik analogies apply.   I think this may have been done to avoid limit problems and undefined errors in the math as you go to zero, but it should not be hard to update the tables. Just bang in a couple more rows to taper the performance off to "accelerated stalls suck" and "50 cals have higher muzzle velocity and less arc drop at 4G+." It's not hard.

I also look forward to the fixing of the padlock feature. Call me a baby, but even with TrackIR, it is helpful, especially fighting in the vertical.

I also got a new Warthog Stick and LOVE the brand new gimbals and sensors!  

Edited June 24 by Squiffy

[ricktoberfest]

On 6/23/2025 at 9:40 AM, Squiffy said:

I also got a new Warthog Stick and LOVE the brand new gimbals and sensors!  

Did they update the gimbal and sensors, or just because they are new and fresh?

[Squiffy]

Both for me since the Cougar is quite old and had pot metal gimbals. I'm not sure if the Warthog has been updated since release but the quality is a step above the Cougar at least. It integrates pretty easily too with the old stick parked out of the way in front of the throttle and beside my left desktop speaker. It was also easy to copy and paste my maps in the controller menu within DCS. Just open the aircraft menu and find the stick columns. Copy from on to the other. 

Edited June 27 by Squiffy