Viper with the Hornet's slow speed handling?Possible or not?

Always wondered why the F-16 has a tailhook, or how big a bigmouth F-16's mouth really is ? Find it out here !
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Patriot

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Unread post24 Apr 2019, 21:04

Roger copy.

Btw, Ive never up until now heard of "paddle switch" that is attached to the stick in the Hornet. I guess the MPO switch in the Viper cannot be used for augmenting manuverability in combat, only to do a post-stall recovery, right?
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sprstdlyscottsmn

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Unread post24 Apr 2019, 21:23

Correct
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Unread post24 Apr 2019, 21:28

So, what would have happen if Id flip the MPO switch while being in the middle of 9g turn in the Viper? Can it be activated from the HOTAS or a pilot can enable it only by reaching out to the cockpit?
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Unread post24 Apr 2019, 22:15

I know it is not a HOTAS control, but AFAIK all you would do is rapidly enter a deep stall. You would have no way to manage your AoA.

Think of it this way, the control logic would toggle from "Give me whatever tail deflections are needed for me to be at nine-g right now (tails level to slightly trailing edge up based on the pitch moment chart)" to "Give me full trailing edge up range of motion on the horizontal tail and do it right now". The result would be uncontrollable pitchup well past stall AoA.

Not only does the F-16 have a high nose up pitch moment at "Stick Full Back" at 0-15 AoA, but it only gets greater until past 25 degrees AoA. Not only does your pitch increase, but the rate at which your pitch increases keep increasing until this point. By 50 degrees AoA your rate of pitch increase has slowed to what it was when you hit the switch, but it still going up rather fast. By the time the rate of pitch increase has slowed to where you realize what happened you are likely already at 60 AoA and deep stalled. The good news here is that you already hit the MPO switch so you can begin trying to rock yourself out of the stall, but your position in the fight is lost.
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ricnunes

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Unread post24 Apr 2019, 22:40

A "Viper with the Hornet's slow speed handling"?

Well that would be a F-35A :wink:
A 4th/4.5th gen fighter aircraft stands about as much chance against a F-35 as a guns-only Sabre has against a Viper.
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Unread post24 Apr 2019, 23:18

ricnunes wrote:A "Viper with the Hornet's slow speed handling"?

Well that would be a F-35A :wink:

Yeah, I went out of my way to not go there and stick with the issues of the F-16 airframe.
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Unread post24 Apr 2019, 23:43

I personally still have a hard time to understand how in the world this obese flying concrete mixer (bomb) truck with its tiny wings and huge wingloading can have better slow speed autorithy / high alpha stability / handling properties than the sleek sexy Viper.. :doh:

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Unread post25 Apr 2019, 01:01

The F-35 looks like a v-hull boat whereas the F-16 looks like a catamaran with thin hulls.
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Unread post25 Apr 2019, 01:54

Patriot wrote:So, what would have happen if Id flip the MPO switch while being in the middle of 9g turn in the Viper? Can it be activated from the HOTAS or a pilot can enable it only by reaching out to the cockpit?


If you could do that, you would almost certainly be faced with instant disintegration of the airplane. If you have the airspeed for 9g (probably above 400kt), wing/fuselage lift and down tail load will rapidly increase AoA, g, and structural load, resulting in rapid disassembly of the airplane.
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Unread post25 Apr 2019, 10:30

Roger that John. That make sense. The loads raise exponetially with speed so the aoa and likewise turn rate at some point have to be limied more and more so the loads wont kill the plane and the pilot.

What if Id do the same at lower speed.. at arround 250-350kts when pulling say 4-6gs? That's the speed range where Hornet or Raptor does their vertical takeoff consisting of massive onset of turn rate. Does in the Viper a momentary increase of max stab deflection by let's say 50% would help in moving the nose effectively at an adversary aircraft (lag pursuit ---> pure/lead pursuit) or help do similar vertical takeoff without loss of control?
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Unread post25 Apr 2019, 16:05

Cannot really say. You're trying to do something the airplane wasn't designed for. To be safe, you'd need to do a complete analysis of tail loads, wing loads, fuselage loads, pitch acceleration, internal equipment loads, etc.
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Unread post25 Apr 2019, 16:28

johnwill wrote:Cannot really say. You're trying to do something the airplane wasn't designed for. To be safe, you'd need to do a complete analysis of tail loads, wing loads, fuselage loads, pitch acceleration, internal equipment loads, etc.

This is the part I focused on. The F-16 was not meant to fly without the computer. The MPO was for deep stall recovery only as the plane was already not flying at that point.
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Unread post25 Apr 2019, 23:09

Patriot wrote:I personally still have a hard time to understand how in the world this obese flying concrete mixer (bomb) truck with its tiny wings and huge wingloading can have better slow speed autorithy / high alpha stability / handling properties than the sleek sexy Viper.. :doh:

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Looks can be deceiving ;). This has been discussed many times before on this forum especially in the F-35 vs Rafale thread but basically at the front end the F-35 has a lot of features that keep generating vortex lift at very high AoA, lerx/strakes/chines, while at the back the big twin tail surfaces give great directional authority at this high AoA. The end result is that it points very well and can extricate itself from this extreme pointing with no stalling or energy deficiencies i.e. quickly. It's actually a very clever design to get such a short boxy stubby shape to maneuver so well at all AoA especially when it is primarily optimized for stealth !

https://www.quora.com/How-is-the-aerody ... ogfighting

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Unread post26 Apr 2019, 19:42

Good post. Thank you.
So aerodynamically it looks like the low wingloading is the least important factor for the ability to fly slow (up until recently I thought rather otherwise). It looks to me like F-35 thanks its slow speed controlability to the huge stabs and to the fact its tail has roughly 2x the surface area of the F-16 tail. Big stabs, big tail, big rudder working together = lots of directional authority almost like with TV nozzle
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Unread post26 Apr 2019, 23:57

Low wing loading gives you better sustained turn rates and high thrust/weight ratio gives less energy bleeding in an instantaneous turning state. Low wing loading does help you fly slower but only in a sustained state which is why the F-35C has the bigger wings. High AoA ability is about generating vortex lift over your wings after the main wing has stopped producing most of its lift in a raised state so usually canards, strakes, chines, leading edge root extensions and other forward protuberances.

Alternatively you can just cheat like the Russians do and have TVC nozzles which provide angled thrust instead of lift however without lift all you are doing is pointing while you are falling. Having big widely spaced twin tails then help you control direction at high AoA. The F-16 is primarily a high energy sustained turner and its FCS has deliberately left a little AoA/instantaneous ability on the table to deliver this goal optimally as it will never match a Hornet or F-35 in AoA ability so doesn't bother trying to by hampering its main strength, continuous turning. At sea level the best sustained turner even now is either an F-16 or Flanker depending on fuel load. F-16 also accelerates and climbs very well, it's a classic hotrod.
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