Aerodynamically Limited MiG-17s v1.1

[Caesar]

View File

Aerodynamically Limited MiG-17s v1.1

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Aerodynamically Limited MiG-17s v1.1

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Description:

This is a mod which limits the maneuverability of the stock ThirdWire MiG-17, -17F and -17PF at high subsonic speeds, especially above .8M.  It has long been published that the MiG-17's lack of hydraulically boosted controls prevented the pilot from turning much harder than 2-2.5g as the aircraft got beyond 400 knots (especially by 450).  The stock TW MiG-17s, however, have in excess of 10g authority at the mid-to-high 400s of knots, and this is one of the reasons they are commonly called "UFOs" - they can out-turn almost any fighter anywhere in the envelope.

This mod adjusts both the lift coefficient and the aerodynamic pitch dampening coefficient to reduce the MiG-17's ability to pull high-g turns at airspeeds exceeding .8 Mach.  This provides the player with the ability to utilize real-world speed tactics employed by F-4, F-8 and other aircrews against the MiG-17.  Keep the fight fast, and you can now out-turn the FRESCO.  

This mod does NOT adjust the lower-speed performance of the FRESCO.  As such, if you try to get into the phonebooth and burn away your energy, expect the same results as before.  If you choose to fly the MiG-17 with this FM modification, it adds a degree of challenge and realism in that just like the AI, you won't be able to load a 12g turn at 500knots anymore, and will have to pay attention to airspeed.  The speedbreak is your friend!  I personally had no problem dogfighting with the FM, but it did require better energy management in that it requires you to keep the aircraft neither too slow, nor too fast.

V1.1 (23 Nov 17) has also changed the engine response time for the MiG-17's VK-1F engine.  It is reported in Red Eagles that the engine took approximately 15 seconds (p.112) to go from idle to full military power.  Most engines from the 50s and 60s had slow response times (e.g., the TF-30 taking approximately 8 seconds to go from idle to military and another 4 to stage up to Zone 5), and this required a bit of thinking and tactics to work around.  "Jose" Oberle (Lt Col, Ret) explained that the engine worked well enough if kept above 80 percent power, but pulling back to idle, then pushing back towards military power "took forever" (Ibid.), and that the easiest way to handle decelerating was to keep the engine at 80 percent and deploy the speed brakes.  The AI isn't harshly impacted by this limitation, but a player using this data.ini will have to consider this limitation.  If, as a player, you do not want to deal with the slower engine response, the original entry is simply commented out, and can be restored by editing the .ini.

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Whats in it:

There are three data.inis contained in this mod.  One for the baseline MiG-17, one for the MiG-17F and one for the MiG-17PF.  This mod adjusts the ThirdWire MiG-17s and will work with any version of StrikeFighters 2, including merged and single installs.

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Installation:

1.  Unzip the contents of the "Aero_Limited_MiG-17sV11.7z" file into a folder

2.  Open the folder.  Copy the contents of the folder (MiG-17, -17F, and -17PF folders) into your SF2 mod folder's Objects\Aircraft folder, allowing all files to overwrite.

3.  The Data.ini files should already be read only, but if not, set them to read only so the game does not re-write or over-write the data file with the game's original files upon booting up (this happens sometimes when a mod changes a core game file).

4. Go fly!

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Credits:
FM: ThirdWire
Mod: Caesar

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Some open-source examples of airspeed and engine limitations of the MiG-17:

From "Scream of Eagles," "Tooter" Teague (who flew one of the captured MiG-17's) put it that: "We found out very quickly that the MiG ['17] goes out of control at 450 knots...He [the '17] locks up at about 425 and he goes absolutely left wing down...his wing warps...so if he goes 500 knots he's out of control  He's in a left wing roll an can't do anything about it.  So just do 500 knots and it becomes only a question of eyes.  Keeping sight and keeping fast." (p. 138).  

From "Red Eagles": "We had to teach them that if they could - as a defender in an American airplane - get the MiG-17 into the 450-knot regime, and then start to turn, then the MiG pilot would have to overcome this huge aerodynamic load on the tail without any hydraulic assistance.  He may have had the potential to pull 7Gs, but he could probably pull no more than 2Gs because he simply didn't have the physical strength to overcome the loads on the tail." (p.132)  

From "Duke" Cunningham (in "Dogfights): [the MiGs are travelling fast.  Cunningham knows the MiG, lacking hydraulic controls like the F-4, is hard to turn.] "So I looked at him and said 'nope, can't do it,' so I broke into him and he overshot right down below me."

[Engine] From "Red Eagles, New Edition": The VK-1F was slow to respond to movements of the throttle, and it took in the region of 15 seconds for it to go from idle thrust to "military" thrust power setting (the maximum non-afterburning thrust available).  Oberle observed: "This slow engine response was a characteristic of the old engines.  If you kept the power up above 80 percent you had pretty good engine response, but if you ever pulled it back to idle and then pushed the power up to accelerate, it would take forever for the engine to spool back up to the 80 percent rangewhere you finally started getting power." (p.112)

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• Submitter
  Caesar
• Submitted
  03/03/2017
• Category
  ini File Edits

 

[+strahi]

What line of text in the data you changed?

[Caesar]

The CLa and Cmq Mach tables for the stabs.

[+Gepard]

Em, the lack of hydraulically boosted controls was only in the first batches of the MiG-17. Later built planes had hydraulically boosted controls to increase the agility at high altitudes.

In the east german Air Force LSK the planes with hydraulical boost were called MiG-17H, the others MiG-17glatt.

Edited March 4, 2017 by Gepard

[Caesar]

Ok, that's fine, just don't use the modified data in later variants of the -17.

[DaniloE31]

Thank you for this Mod, I love it! My first download for ages!

Edited March 7, 2017 by DaniloE31

[Toryu]

The early MiG-21 also had hydraulic pitch control, yet their high-q performance was nothing to write home about.

Is there any word about the differences in MiG-17 pitch performance between unboosted and boosted?

 

The transonic performance will stay poor due to the lack of a stabilator.

[+MigBuster]

Red Eagles flew MiG-17Fs and PFs with hydraulically boosted controls and Gail Peck does mention it is very sluggish with the boost turned off (in flight test)......they should have a handle by the throttle (like on the MiG-15bis) to turn it on/off.

 

He does also state that the faster you flew the more muscle it took to move the control column. This was especially true with roll commands to the aircraft, even with the hydraulically boosted ailerons.

Above 400kts in a dive he still needed to use 2 hands on the control column to roll or change pitch with added G. 

[Spudknocker]

I Read somewhere I believe it was On Yankee Station that North Vietnamese pilots were usually much smaller in stature than their american or soviet counterparts and that led to high speed high G turns to be much harder... It went on to say that the mythical Colonel Tomb's dogfights were won by forcing F-4's/105's into slow speed flight envelopes as a result.  

 

Whether this is ego boosting nonsense I have no idea but worth thinking about... hard to model pilot strength in a game 

[Caesar]

The only hydraulics I've read about the F and PF having were to the ailerons and the airbrakes, not to the elevators or rudder (and hence lack of pitch control at high speed).  It was prevalent enough to build useful tactics to counter the MiGs over Vietnam and instruct students over Tonopah, so I do wonder which models, if any had hydraulics built to the tailplane apart from the "H" model Gepard mentioned.  

[Toryu]

There is a difference between hydraulic boost and irreversible controls with an artificial feel system.

The former still has direct aerodynamic feedback from the controls and beyond the boost-capability (which is fixed), the same limitations apply as without boost.

The hydraulic boost is basicly just a an enlaged, mechanical bicep.

 

The problem with hydraulically actuated (no matter if boosted, or irreversible) ailerons and high-aspect ratio wings is that even though you'll have some improvement in roll, you'll eventually run into a speed-regime where you'll just twist the wing and the net-effect is a reduced roll-rate as wing-twist and aileron-deflection cancel each other out.

You'll gain better roll-authority between the airspeed at which you'll read max pilot-strenght and the speed where wing-twist becomes significant. This realm is typically not too large - depends on the layout of the original control-systems and it's gearings/ possible boots tabs.

 

As long as there wasn't any substantial beef-up of the wing (improving the torsional stiffness), the hydraulically boosted ailerons don't do too much good above wing-twist speed.

 

The pitch-boost may be a lot more helpful (if the tail can take the additional high-speed loads). Upon reaching Mcrit, things get interesting, though. Elevator-effectiveness blends out and unless there's a possibility of trimming/ moving the whole stabilizer (e.g. Skyhawk or Hunter), pitch-authority will decrease.

You'll run into hinge-moment issues and the small elevator combined with an aft-moving center of pressure is less effective the faster (Mach) you go.

 

In the end, it all comes down to how much additional force the hydraulic boost could field.

[Caesar]

Updated to v1.1; adjusted engine response time (see description).