F-35 and Airshows

Discuss the F-35 Lightning II
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steve2267

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Unread post06 Sep 2018, 17:01

marsavian wrote:The unique advantage I think F-35 has was what was originally considered a disadvantage is that it bleeds speed faster from instantaneous to sustained to high AoA maneuvering so it can get to effective high AoA maneuvering quicker from higher speed than any other jet. I think this is what was meant by the pilots discovering what it could uniquely do and shaping their ACM tactics around it. I thought the initial critics would be proven wrong by the conventional maneuvering but I wasn't expecting the kind of useful high AoA maneuverability you only usually see in TVC jets although the F-18 also does it well but lacks the acceleration of the F-35 to get out quickly from that regime.


I think you make a good point about the quickness with which the F-35 can transition to high angle-of-attack maneuvers. IMHO, however, the real advantage lies in this HUGE toolbox of tricks and maneuvers that the F-35 hands the pilot along with the carefree handling that enables the pilot to fly with precision, or reckless abandon, and to choose whatever tool he wants out of that toolbox whenever he wants.

Rate with a Viper? Check.
Get the smash back like a Blk 50 Viper with its hair on fire? Check.
Radius like a Hornet? Check.
Nose point (probably better than) like a Hornet? Check.
6-8 second reversals? Check.
Imitate a Raptor at high alpha? Kindasorta - check.
Hit the disappear switch? In spades.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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Gums

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Unread post06 Sep 2018, 23:00

Salute!

Good points, Steve and Mars.

I would point out that we lowly Viper folks back in 1979 suprised our visitors from Miramar with the transition from a closure at 400 + KCAS to a knife fight without blinking an eye. The A-4 folks that came to Utah found we could slow and turn very well below 200 KCAS while maintaining complete control as they were in their last-ditch maneuver. But best thing was still have enuf excess thrusties to move a horizonal scissors vertically.( as could the Eagle in those days). The rule of thumb then was you could go over the top in a "loop" type maneuver at 200 KCAS or above. Hesitate at top and pirouette to get pointed out ahead of the bandit and then come back down for guns or a Lima shot across the circle.

Looks like the Stubbie can use that "rudder turn" at a ridiculous AoA and maintain altitude at the top of the zoom better than we could, as we had to come down on the limiter while rolling for a short time before reducing AoA.

I will guarantee that the Double Ugly, Eagle, Tomcat and all but the Hornet could not roll and turn very well below 200 KCAS without departing or shaking so badly you couldn't aim.

I like what I am seeing.

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steve2267

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Unread post06 Sep 2018, 23:55

Gums wrote:I would point out that we lowly Viper folks back in 1979 suprised our visitors from Miramar with the transition from a closure at 400 + KCAS to a knife fight without blinking an eye. The A-4 folks that came to Utah found we could slow and turn very well below 200 KCAS while maintaining complete control as they were in their last-ditch maneuver. But best thing was still have enuf excess thrusties to move a horizonal scissors vertically.( as could the Eagle in those days). The rule of thumb then was you could go over the top in a "loop" type maneuver at 200 KCAS or above. Hesitate at top and pirouette to get pointed out ahead of the bandit and then come back down for guns or a Lima shot across the circle.

Looks like the Stubbie can use that "rudder turn" at a ridiculous AoA and maintain altitude at the top of the zoom better than we could, as we had to come down on the limiter while rolling for a short time before reducing AoA.

I will guarantee that the Double Ugly, Eagle, Tomcat and all but the Hornet could not roll and turn very well below 200 KCAS without departing or shaking so badly you couldn't aim.

I like what I am seeing.


Gums, to make sure I'm tracking you... is the maneuver Stubby pulls beginning at 1:04 in the video that gta4 (re)posted above similar to what you describe? If I'm counting my seconds correctly, he reverses course in 6-8 seconds, goes up... spies his prey, wherever it might be, then leisurely rolls / yaws over and around into a gun pass or an X-shot? It just seems so effortless.

Question: Is this the so-called Mongoose? Or just an example of a velocity vector roll? I am also thinking this is a real life demonstration (i.e. not a NASA research dealio) of the Herbst maneuver / J-turn. I am thinking this is NOT the so-called pedal turn, which from the way pilots seem to describe it, are all done using the pedals. Well, certainly it is not a near vertical, descending spiral turn as flown by Billie Flynn @ Paris in 2017.

I stepped through this sequence frame by frame and noted some interesting, unconventional aerosurface deflections.
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Mongoose_or_velocity_vector_roll.jpg
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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Unread post07 Sep 2018, 00:20

Gums,

How did you early Viper guys fair against the Hornet? A week ago I talked to a Lt Colonel with over 20 years on the F-16. He said that the Hornet is "extremely dangerous" from 300Kts and under. And that if any Viper guy doesn't bring his A game it is easily over. He said that he would rather fight a Hornet in a Block 15 rather than a Block 50/42 if the speeds get that low-
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Unread post07 Sep 2018, 01:11

Salute!

Only saw the Hornet tice and we both disengaged before getting into a fight - Red Flag and another exercise.

I would take the Block 15 or 30 with the big engines. Hornet had better nose-pointing ability when slow, as did the Eagle, so don't get slow.

Try reading "Mover"'s articles, as he flew both.

https://fightersweep.com/1494/hornet-vs-viper-part-one/

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Unread post07 Sep 2018, 02:13

I am very curious about how hornets/superhornets performed against su30mkms during their excercise in Malaysia. Haven't seen any report or pilot interview. Anyone had a chance to talk to a pilot?
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Unread post07 Sep 2018, 02:22

johnwill wrote:Something else I've noticed that might act like TVC in those abrupt pitch maneuvers is that both trailing edge flaps can be seen to be up during the maneuver. F-35 wings are so far aft, the flaps seem to act as elevons on a delta. Here is an example at 0:08. I've noticed it in several other videos.

https://youtu.be/6Kg-ztkPDok


How about that the leading edge slats are pointing "nose down" during those maneuvers? It's fairly obvious in for example 0:06 and 0:16 of the same video. My gut instinct is to say that the wing is actually decreasing its AOA relative to the fuselage, to let the fuselage do more of the work in producing lift (perhaps to increase wing life), is that more or less correct aerodynamically?
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steve2267

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Unread post07 Sep 2018, 02:32

Extended leading edge flaps may decrease the angle-of-attack (the angle between the relative wind and the line drawn between the front tip of the airfoil and the trailing tip of the airfoil, but they also greatly increase the camber (curvature) of the airfoil, or in this case, the wing which can increase the lift the wing generates. Also, from an offline conversation with Gums, it would seem that the leading edge flaps can also have a great effect on buffet (i.e. lessen buffet). I would not read into LEF extension as decreasing wing lift and increasing body lift. Quite the opposite, IMO.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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Unread post07 Sep 2018, 02:54

Leading edge flaps increase camber and add to lift.
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Unread post07 Sep 2018, 03:26

Salute!

What Steve said ( mostly).

My GD FLCS tech document (from the pre-historic FSD days) is in the garage, aka "geriatric park".,
1500 miles away, as I am up in the high country for another three weeks +/- So this is from memory, such as I have left.

First, the leading edge flaps ( LEF) were not slats like the F-100 and F-4 had. They were like folding a percentage of the wing's leading edge down, and you can see that implementation on the Hornet, Sluf and many commercial airliners.

The LEF deflection was variable and had a significant mach input variable besides the AoA. I' m fairly sure we also had a bit of flaperon deflection included in the equation once at higher AoA. The result was we had variable camber for the overall wing that the air molecules saw as they raced by. Of course, once slow enuf and at a high AoA the suckers were full down. The plot of AoA to Cl did not have a sharp hook at "stall" AoA, and was relatively flat for many degrees of AoA. This is also seen with many swept wing designs and is really obvious on deltas.

Besides the obvious help that basic leading edge devices provide, the Viper LEF's also helped directional stability. So who doesn't like keeping the nose from slicing at high AoA, huh? That also helped the vortex lift by keeping those air molecules moving straight down the plane from nose to tail.

Gotta go.

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spazsinbad

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Unread post07 Sep 2018, 04:08

:devil: Difficult to keep up with all this USAF NonNavAv slang 'bout FALCONIEs & stuff. However perhaps this DASH One? :shock:

https://www.filefactory.com/file/u1vvz4 ... Manual.pdf (37Mb) is helpful?

"NATOPS Flight Manual #1F-F16A-1 for the General Dynamics F-16A/B Fighting Falcon aircraft. This manual is dated August 14, 1995."

32 page PDF extract attached MAY BE USEFUL? About Flight Controls and things I do not comprehend. :drool:
Attachments
F-16ABflightManualCover.gif
F-16beforeTOreadThis.gif
Control STUFF F-16A_B Fighting Falcon Flight Manual pp32.pdf
(2.27 MiB) Downloaded 289 times
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
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Unread post07 Sep 2018, 04:42

I think the only way to stop those “f35 can't turn” maniac is to arrange BFM excersice against Russian fighters (flankers or fulcrums)
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Unread post07 Sep 2018, 05:48

Yeah I guess I should've called them leading edge "flaps" not "slats" since they simply rotate. The thing is though, although they increase camber, in this situation the trailing edge flaps are pointing upward (tail up). So the camber doesn't really change (assuming the leading edge flaps extend downward as much as the trailing edge flaps extend upward), but the wing's overall AOA points downward. IIRC though more of the lift is generated near the front part of the wing, so maybe increased camber there is more important. Bleh so not sure how to think about this. It's been too long since my aero courses.
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Unread post07 Sep 2018, 05:55

Gums wrote:Salute!

The LEF deflection was variable and had a significant mach input variable besides the AoA. I' m fairly sure we also had a bit of flaperon deflection included in the equation once at higher AoA. The result was we had variable camber for the overall wing that the air molecules saw as they raced by. Of course, once slow enuf and at a high AoA the suckers were full down.



Gums, the TEF were not scheduled with AOA like the LEF were, but did move 2 deg up supersonic. That was to help reduce tail trim load and drag when wing lift moved aft a bit supersonic. Also supersonic, the LEF were fixed at 2 deg up, no matter what AOA was.

Spaz, thanks for posting the FLCS pages from the Blk 10/15 -1. Now we can refer to that when discussing the g/AOA limiter function, Fig 1-44 on page 1-126.
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steve2267

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Unread post07 Sep 2018, 06:09

vanshilar wrote:Yeah I guess I should've called them leading edge "flaps" not "slats" since they simply rotate. The thing is though, although they increase camber, in this situation the trailing edge flaps are pointing upward (tail up). So the camber doesn't really change (assuming the leading edge flaps extend downward as much as the trailing edge flaps extend upward), but the wing's overall AOA points downward. IIRC though more of the lift is generated near the front part of the wing, so maybe increased camber there is more important. Bleh so not sure how to think about this. It's been too long since my aero courses.


vansh, you make a good point about the TEF pointing upwards. I think we are into regions where I would want to be looking at wind tunnel data, at a minimum, before trying to make definitive statements about the effects of deflected aerosurfaces, esp. on modern military aircraft (>= gen 4) where FCL or CLAWs can and do deflect control surfaces in non-obvious ways.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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