"Pedal turn" versus "Conventional turn"

New and old developments in aviation technology.
  • Author
  • Message
Offline

lbk000

Senior member

Senior member

  • Posts: 350
  • Joined: 04 May 2017, 16:19

Unread post01 Jan 2019, 18:37

steve2267 wrote:In air show demos, you never show your best cards...

Certainly, but the nature of the "best card" is a good question. F-35's best card may not be a maneuver but rather an electronic attack capability, for example. The most powerful things are rarely flashy.

Aerodynamics is a field that has relatively limited growth potential. The rules are written by powers beyond Human control.
In the area of software, Man is God. We are free to rewrite the rules that we made, and exploit what is effectively a microcosm of our own device.

The physical realm is running out of loopholes to exploit; it's easier and smarter to get everyone to play a new game that is riddled with opportunities.
Offline
User avatar

steve2267

Elite 2K

Elite 2K

  • Posts: 2532
  • Joined: 12 Jun 2016, 17:36

Unread post01 Jan 2019, 18:59

The pilot who told me that ("never show your best cards") is well aware of the F-35's kinetic potential, and his comment was specifically in regards to F-35 and air show routines.

With the possible exception of one forum member here who seems absolutely in love with pedal turns, I do not think anyone is saying the pedal turn is the be-all and end-all of BFM / ACM contests. Most seem to consider it just another tool in the proberbial BFM toolbox, but a very nice tool to have, and it hints at a bunch of other possibilities. I do not recall "Dolbe" Hanche ever going on about the pedal turns (though perhaps they had not been completely worked out at the time of his comment(s)), but he really did like the braking ability of the Lightning... enabling him to much more quickly gain a position of advantage compared to the Viper, and to "stick like glue" onto his opponent.

However, the Bug and Super Bug community has probably developed most of these "tricks" by now, but that is just a guess on my part -- based on the several comments by former Bug drivers: "It's like a Hornet with FOUR MOTORS!"

ETA: I believe quicksilver has already commented that the pedal turn is very similar to (or the same thing) as the Hornet's pirouette. The problem for the Bug driver is he really is out of energy post-pirouette, whereas the Lightning driver has the smash to quickly regain energy.
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.
Offline

lbk000

Senior member

Senior member

  • Posts: 350
  • Joined: 04 May 2017, 16:19

Unread post01 Jan 2019, 19:29

steve2267 wrote:ETA: I believe quicksilver has already commented that the pedal turn is very similar to (or the same thing) as the Hornet's pirouette. The problem for the Bug driver is he really is out of energy post-pirouette, whereas the Lightning driver has the smash to quickly regain energy.


Yes, pedal turn is the Pirouette. In the manuals it is referred to as [FCS] Pirouette Logic.

I think no aircraft embodies the saying of "The Devil is in the details" more than the F-35. What is important isn't the F-35's top end speed, or its bottom end speed, but in how dynamic its energy state can be inside its performance envelope. Similarly, for maneuvers, the magic may not so much in any one specific maneuver, but in how well or quickly it can transition between them.
Offline
User avatar

steve2267

Elite 2K

Elite 2K

  • Posts: 2532
  • Joined: 12 Jun 2016, 17:36

Unread post01 Jan 2019, 19:34

tailchase wrote:interesting to compare with the turn here at 4:00

https://youtu.be/IgD4QvxhFyU

(pedal turn and extreme "normal" turn). Which one is the most useful in your mind? In what circumstances?

PS Sion is a very specific place for airshows and should fit very well to F-35 demo (mostly in vertical plan). We haven't seen it yet there, but with the reopening of swiss eval, we will soon i hope.


Which one is most useful? The answer, as almost always is, it depends...

If the following illustration depicts the pedal turn or pirouette, it can be extremely useful to counter or defeat a turning adversary:
Image
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.
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 24499
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post01 Jan 2019, 19:34

tailchase wrote:interesting to compare with the turn here at 4:00 https://youtu.be/IgD4QvxhFyU (pedal turn and extreme "normal" turn). Which one is the most useful in your mind? In what circumstances?
PS Sion is a very specific place for airshows and should fit very well to F-35 demo (mostly in vertical plan). We haven't seen it yet there, but with the reopening of swiss eval, we will soon i hope.

Does SION get this high (spectators require oxygen) & 'don't show best stuff'? Keep those LOONY LENZ strapped on TIGHT!

https://a855196877272cb14560-2a4fa819a6 ... 72a5_o.jpg

Image
Attachments
F-35AhighAoAtestWeaponBayOpenHiAltPDF.jpg
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
Offline
User avatar

steve2267

Elite 2K

Elite 2K

  • Posts: 2532
  • Joined: 12 Jun 2016, 17:36

Unread post01 Jan 2019, 19:42

The graphic I just linked to above may be found here:

https://www.nasa.gov/centers/dryden/his ... RV/rd.html

I had previously posted several of these images earlier in this thread.

Interestingly, the above image is referred to as an offensive spiral as opposed to a defensive spiral.

Pirouette, Herbst maneuver, J-turn, Pedal turn all seem to be related and within the family of high alpha, post-stall maneuvers. Some may be more yaw driven (pedal turn?), whereas others such as the J-turn or Herbst maneuver, appear to be more related to velocity vector (or flight path vector) rolls.

These maneuvers are fun to watch and discuss, and they may very well have a certain place in the Lightning driver's BFM / ACM toolbox... but given the frighteningly awesome demonstrated performance of IIR HOBS missiles like the AIM-9X and helmet mounted sighting systems... until DIRCM or some other DEW demonstrates extremely high defeat ability of IIR missiles... I don't think I'd want to engage WVR.
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.
Online

quicksilver

Elite 3K

Elite 3K

  • Posts: 3057
  • Joined: 16 Feb 2011, 01:30

Unread post01 Jan 2019, 20:30

It appears you guys are in somewhat violent agreement.
Online

quicksilver

Elite 3K

Elite 3K

  • Posts: 3057
  • Joined: 16 Feb 2011, 01:30

Unread post01 Jan 2019, 20:39

lbk000 wrote:
steve2267 wrote:In air show demos, you never show your best cards...

Certainly, but the nature of the "best card" is a good question. F-35's best card may not be a maneuver but rather an electronic attack capability, for example. The most powerful things are rarely flashy.

Aerodynamics is a field that has relatively limited growth potential. The rules are written by powers beyond Human control.
In the area of software, Man is God. We are free to rewrite the rules that we made, and exploit what is effectively a microcosm of our own device.

The physical realm is running out of loopholes to exploit; it's easier and smarter to get everyone to play a new game that is riddled with opportunities.


An astute observation.
Offline

lbk000

Senior member

Senior member

  • Posts: 350
  • Joined: 04 May 2017, 16:19

Unread post01 Jan 2019, 23:55

steve2267 wrote:Interestingly, the above image is referred to as an offensive spiral as opposed to a defensive spiral.

The "offensive spiral" refers to the blue aircraft executing the pirouette maneuver.
The red defending aircraft is executing the classical defensive spiral.

Pirouette is an inherently offensive move. It has relatively poor defensive potential, as it is about converting as much motion into angle as possible. The most defensive thing about the pirouette is that it quickly resolves the defensive spiral, which as a delaying tactic may otherwise afford the defender enough time for help to intercede.
Offline
User avatar

steve2267

Elite 2K

Elite 2K

  • Posts: 2532
  • Joined: 12 Jun 2016, 17:36

Unread post02 Jan 2019, 00:30

I must confess, you have me at a bit of a disadvantage. In your (re-written) post from 9:38am MST this morning, you state
lbk000 wrote:The pedal turn is effectively a defensive spiral with minimal radius characteristics. By claiming the inside of the spiral, the pedal turn possesses a positional advantage and mitigates a turning defender's aspect defense.

However there is more than one way to skin a cat -- simpler ways too. The pedal turn is relatively elaborate and an opponent may be reluctant to enter a defensive spiral. The pedal turn is not necessarily a good defensive maneuver either; it's very wasteful from an energy standpoint, like TVC maneuvers. Energy conservative, aerodynamic maneuvers will always be the most desirable maneuvers at the end of the day, it's just that when someone brings the rock against your scissors, you have to pull out the one-off counter for it.


But here you state

lbk000 wrote:
steve2267 wrote:Interestingly, the above image is referred to as an offensive spiral as opposed to a defensive spiral.

The "offensive spiral" refers to the blue aircraft executing the pirouette maneuver.
The red defending aircraft is executing the classical defensive spiral.

Pirouette is an inherently offensive move, it has relatively poor defensive potential against third party attackers. Two aircraft locked in the classical defensive spiral are essentially at a stalemate as neither will be able to gain a significant angular advantage for a kill shot. The pirouette/pedal turn is sort of an all-in move to break that stalemate by sacrificing even more energy than the other aircraft in order to rapidly achieve a shot solution. It's expensive, but still cheaper than letting the spiral play out all the way down to the deck.


whereas the blue aircraft appears all the world to me to be performing a pedal turn as demonstrated by Billie Flynn in Paris circa June 2017.

I am no BFM / ACM expert, so I claim no expertise in stating whether a pedal turn is better used as an offensive or defensive maneuver. However, I can imagine it being used in both circumstances. Specifically in an offensive situation, if somehow finding oneself in a WVR merge, I could see a Lightning driver executing any number of tactics, from a climbing, high alpha bat turn we have seen into recent demos, to immediately going vertical, keeping eyes on the bandit, and pulling over the top into a descending, high alpha pedal turn to quickly go for a HOBS Aim-9x shot. I also don't see how this is terribly elaborate, especially given how pilots have all claimed how easy it is to fly / control the Lightning.

Perhaps you can clarify whether the pedal turn is an offensive or defensive "spiral."
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.
Offline
User avatar

steve2267

Elite 2K

Elite 2K

  • Posts: 2532
  • Joined: 12 Jun 2016, 17:36

Unread post02 Jan 2019, 00:51

As for the pedal turn being an energy depleting, descending maneuver, I'm not sure I buy that either. Certainly, we have only seen it performed to date in a descending manner, but unless a Lightning driver coughs out the details (i.e. control inputs) of how to perform the pedal turn, the words "pedal" + "turn" used to describe the maneuver sure seem to suggest stomping on the rudder pedals enough to generate the required yaw rotational rate. I would imagine the only pre-requisites are that the aircraft be at a certain post-stall, high alpha flight condition with airspeed (or Q) below certain parameters... then stomp away to slew your nose as desired.

From an ACM perspective, how hard is it to imagine
Image
a pilot entering that maneuver, and then at [4] or [5] converting from a post-stall velocity vector roll (pirouette?) to a pedal turn, as necessary to slew his nose around for a HOBS Aim-9x snapshot? In such a scenario, high alpha & low dynamic pressure, a pedal turn may be very viable in an ASCENDING situation. No?
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.
Online

quicksilver

Elite 3K

Elite 3K

  • Posts: 3057
  • Joined: 16 Feb 2011, 01:30

Unread post02 Jan 2019, 01:18

Is it offensive or defensive? I’ve seen it used in both circumstances and/or for both ends. Depends on the circumstance.
Offline
User avatar

steve2267

Elite 2K

Elite 2K

  • Posts: 2532
  • Joined: 12 Jun 2016, 17:36

Unread post02 Jan 2019, 01:27

QS, this may be a naive question, but can you shed some light on the Hornet pirouette? Is it principally a velocity vector roll primarily performed with lateral stick? Or is it a pedals-only maneuver? At what angles of attack is it initiated or performed and at what indicated airspeeds? Of course, feel free to tell me to pound sand.
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.
Offline

lbk000

Senior member

Senior member

  • Posts: 350
  • Joined: 04 May 2017, 16:19

Unread post02 Jan 2019, 01:31

Sorry, it must be confusing for you because there's a bit of a perspective shift going on between the concept of "defensive spiral" and "offensive spiral".

The Defensive Spiral is so named because it's a passive, defensive move initiated by a defending aircraft to deny an attack.
The Pirouette is an Offensive Spiral, because it's generally a move initiated by an attacker to exploit the defender's maneuver.

Pedal Turn = Pirouette = Offensive Spiral
These are all synonyms.

The Hornet has Pirouette Logic. It's commanded by simultaneous lateral stick and rudder inputs.
Here, this will probably be better than a written explanation:
https://www.youtube.com/watch?v=b2wTpXGhiWE
Last edited by lbk000 on 02 Jan 2019, 01:36, edited 2 times in total.
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 24499
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post02 Jan 2019, 01:34

Wot a shame 'dannyboyo' Dan Canin was not able to tell us more - it is a real shame that CODE ONE has now coded.
Semper Lightning: F-35 Flight Control System
09 Dec 2015 Dan “Dog” Canin [LM F-35 Test Pilot]

"...turn coordination in FBW airplanes can be very sophisticated. Generally, the F-35 tries to keep sideslip near zero, but in some cases it intentionally creates adverse or proverse yaw as necessary to control roll and yaw rates. We’ll talk about the use of pedals at high AOA in a later article, [AFAIK he NEVER DID] but, for general flying around, the best coordination we’ll get is with our feet on the floor...."

Footnote 2: "[2] The Wright brothers incorporated automatic rudder coordination because they had no choice. Laying prone and controlling the aircraft’s roll with their hips, there was no practical way to control the rudder independently, so they linked the rudder wires to the wing-warp hip cradle. Interestingly, the Wrights deleted the interconnect in their later models, preferring to have direct control of sideslip and to rely on pilot skill for coordination. It was decades before airplanes incorporated both: automatic coordination with roll, with additional yaw command available via the pedals."


Source: http://www.codeonemagazine.com/article.html?item_id=187
Last edited by spazsinbad on 02 Jan 2019, 02:20, edited 1 time in total.
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
PreviousNext

Return to Technology

Who is online

Users browsing this forum: No registered users and 7 guests