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#3996322 - 08/15/14 11:14 PM Control at high speed  
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scrim Offline
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When I get to Mach 0.9, my controls just stiff up completely, and even small input is liable to cause adverse yaw (IIRC, that's the correct name for it. Essentially going out of control). But in several documentaries about the Sabre I've heard veteran pilots first hand talking about chasing MiGs in up to 0.95 Mach and shooting them down. Now, in DCS that just won't happen, the controls are extremely unpredictable at that speed.

How's everyone else's take on that?

#3996336 - 08/15/14 11:33 PM Re: Control at high speed [Re: scrim]  
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Not talking the F-86 directly as I can't speak to the accuracy of its FM in DCS, but:

An engineer might be able to give a better answer but it has to do with boundary layer separation in trans-sonic flight. The flight controls on the trailing edge on the wing basically lose their effectiveness since they're operating in separated or dead air.


Last edited by boomerang10; 08/15/14 11:35 PM.
#3996848 - 08/17/14 12:23 AM Re: Control at high speed [Re: scrim]  
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I have never heard of the Sabre having control problems at high speed. As a matter of fact, a Sabre was the second airplane on history to break the sound barrier. Admittedly, with a slightly nose down attitude. But still, the test pilot did not loose control of the F-86, even at Mach 1.
Also, to successfully combat the faster MiG-15's, the pilots of the early model Sabres had to constantly fly the airplanes, "on the mach," as they used to refer to transonic flight. They had to push the jet to the very limits of its capabilities to fight the MiGS and would never have been so successful if they had been constantly loosing control of their planes.


"From our orbital vantage point, we observe an earth without borders, full of peace, beauty and magnificence, and we pray that humanity as a whole can imagine a borderless world as we see it, and strive to live as one in peace."
Astronaut William C. McCool RIP, January 29, 2003 - Space Shuttle Columbia

#3996856 - 08/17/14 12:36 AM Re: Control at high speed [Re: scrim]  
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That's what I'm feeling about the Sabre right now. At Mach 0.95, if not 0.9 you lose control of the plane for the intents of any accurate flying.

#3996943 - 08/17/14 06:16 AM Re: Control at high speed [Re: scrim]  
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It's not so much a complete loss of control; just reduced control authority with control surfaces at high speed(generally around .8 - 1.2 Mach), along with reduced lateral stability.

Check out this F-86F flight manual http://aviationshoppe.com/f86-sabre-documents-manuals-a-62.html

Specifically, look at sections V and VI, "Operating Limitations" and "Flight Characteristics", respectively.

Some excerpts below:

Last edited by boomerang10; 08/17/14 06:23 AM.
#3997519 - 08/18/14 04:21 PM Re: Control at high speed [Re: scrim]  
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I think you are making a conclusion based on unrelated facts.

So they flew at Mach .95 to shoot down a MiG...that was likely flying at high speed in a straight line and thus required no control inputs from the pilot. They weren't maneuvering at .95, they were racing.



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#3997551 - 08/18/14 05:35 PM Re: Control at high speed [Re: scrim]  
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No, but they were nonetheless maneuvering to put the pipper on target. The small precise adjustments required to do that are impossible to perform when reaching even 0.9 Mach.

#3997694 - 08/18/14 10:39 PM Re: Control at high speed [Re: scrim]  
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Originally Posted By: scrim
No, but they were nonetheless maneuvering to put the pipper on target. The small precise adjustments required to do that are impossible to perform when reaching even 0.9 Mach.


I am pretty sure they weren't enageing while flying 0.9 Mach. They where maybe trying to catch up at that speed, and to close in the distance, however I am pretty sure they didn't do enagements at those speeds.

#3997989 - 08/19/14 04:15 PM Re: Control at high speed [Re: scrim]  
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Originally Posted By: scrim
No, but they were nonetheless maneuvering to put the pipper on target. The small precise adjustments required to do that are impossible to perform when reaching even 0.9 Mach.


It would be useful to link to this anecdotal evidence so it can be brought into some context. Although the manual might not always every condition in real flight (though it should) - pilot stories are often taken out of context with inaccurate figures.


'Crashing and Burning since 1987'
#3998206 - 08/20/14 02:27 AM Re: Control at high speed [Re: scrim]  
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I think you guys aren't understanding something. He says the airplane is almost uncontrollable at that speed. The Sabre pilots weren't just chasing the MiGS so they could fly by and wave hi. Once they caught up they had to get that pipper on the MiG and kill him. If the plane was un controllable, how were they doing that?


"From our orbital vantage point, we observe an earth without borders, full of peace, beauty and magnificence, and we pray that humanity as a whole can imagine a borderless world as we see it, and strive to live as one in peace."
Astronaut William C. McCool RIP, January 29, 2003 - Space Shuttle Columbia


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