Interesting decision on control surface choices

Design and construction
  • Author
  • Message
Offline
User avatar

KamenRiderBlade

Elite 2K

Elite 2K

  • Posts: 2635
  • Joined: 24 Nov 2012, 02:20
  • Location: USA

Unread post12 Jun 2014, 08:05

F-22A: http://upload.wikimedia.org/wikipedia/c ... show_3.jpg
F-35A: http://www.worldtribune.com/wp-content/ ... ighter.jpg
F-35C: http://upload.wikimedia.org/wikipedia/c ... t_test.jpg

So I noticed that all 3 planes have made interesting choices on what type of control surfaces they choose to employ
All 3 planes have
Leading Edge Flaps: http://www.rcuniverse.com/forum/attachm ... 1379184723
That are similar to the F-16's LEF

However, the F-22 and F-35C seem to have:
Flaperons & Ailerons

While the F-35A seem to only have:
Flaperons

Any clue as to why they designed the F-35A / F-35B to have only Flaperons?

With the folding wing on the F-35C, it seems easy to implement the Flaperons & Ailerons

Makes you wonder if just using the F-35C wing as the standard wing across all 3 models would've reduced overall cost and design issues?
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 23305
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post12 Jun 2014, 08:17

I'm just repeating probably info that is on the forum many times over - especially from the 'beginning' of the program. The F-35C needs to be controllable - very well - at the maximum allowed landing weight and speed (145KIAS) and then below that speed / weight -- because the F-35C will always land at Optimum Angle of Attack, according to weight below max. landing weight. So in effect the F-35C may land a lot slower (and lighter) if need be. To achieve this apparently excellent carrier landing characteristics by all test pilot accounts so far, there are a few extra features such as you mention. Some extra spice is added with IDLC Integrated Direct Lift Control (search the forum for 'IDLC' without the quote marks). Only two recent examples below:

Here is one example: viewtopic.php?f=61&t=24210&p=266811&hilit=IDLC#p266811
&
viewtopic.php?f=22&t=24559&p=259918&hilit=IDLC#p259918

Probably my 'how to carrier land' PDFs &/or F-35 specific PDFs at the places you know about will help? One day soon I may update them. Have you had a look at your A-4 question lately?

viewtopic.php?f=46&p=273081#p273081
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
Offline
User avatar

KamenRiderBlade

Elite 2K

Elite 2K

  • Posts: 2635
  • Joined: 24 Nov 2012, 02:20
  • Location: USA

Unread post12 Jun 2014, 08:35

spazsinbad wrote:I'm just repeating probably info that is on the forum many times over - especially from the 'beginning' of the program. The F-35C needs to be controllable - very well - at the maximum allowed landing weight and speed (145KIAS) and then below that speed / weight -- because the F-35C will always land at Optimum Angle of Attack, according to weight below max. landing weight. So in effect the F-35C may land a lot slower (and lighter) if need be. To achieve this apparently excellent carrier landing characteristics by all test pilot accounts so far, there are a few extra features such as you mention. Some extra spice is added with IDLC Integrated Direct Lift Control (search the forum for 'IDLC' without the quote marks). Only two recent examples below:

Here is one example: viewtopic.php?f=61&t=24210&p=266811&hilit=IDLC#p266811
&
viewtopic.php?f=22&t=24559&p=259918&hilit=IDLC#p259918

Probably my 'how to carrier land' PDFs &/or F-35 specific PDFs at the places you know about will help? One day soon I may update them. Have you had a look at your A-4 question lately?

viewtopic.php?f=46&p=273081#p273081


Yup the A-4 responses were great. I'm surprised they didn't put more effort to make the runway as close to perfectly flat as possible.
Offline
User avatar

KamenRiderBlade

Elite 2K

Elite 2K

  • Posts: 2635
  • Joined: 24 Nov 2012, 02:20
  • Location: USA

Unread post12 Jun 2014, 08:39

With the 'C' wing being so much better for control, maybe it would've been better to have all 3 models use 1 wing.

Ergo simplifying the production line and design requirements.

And if the A & B model happen to get better handling, manuevering, and more gas because of it, wouldn't that be better in general?
Offline

coldman

Enthusiast

Enthusiast

  • Posts: 54
  • Joined: 25 Oct 2013, 21:32

Unread post12 Jun 2014, 08:50

KamenRiderBlade wrote:With the 'C' wing being so much better for control, maybe it would've been better to have all 3 models use 1 wing.

Ergo simplifying the production line and design requirements.

And if the A & B model happen to get better handling, manuevering, and more gas because of it, wouldn't that be better in general?

I'd imagine that weight would become a problem with both the A and B if you incorporated the larger wing. Since the B needs to land vertically, it's doubtful the designers thought that the extra control at low air speeds was worth the extra weight of an expanded wingspan.

With the A, having to reinforce a wing that size to the point where it could withstand 9G+ would have probably added quite a bit of weight to the plane as well. Keep in mind all variants are rubbing right up against the maximum weight spec, so there isn't a lot of wiggle room to play around with.

Just my $.02.
Offline
User avatar

KamenRiderBlade

Elite 2K

Elite 2K

  • Posts: 2635
  • Joined: 24 Nov 2012, 02:20
  • Location: USA

Unread post12 Jun 2014, 09:14

coldman wrote:
KamenRiderBlade wrote:With the 'C' wing being so much better for control, maybe it would've been better to have all 3 models use 1 wing.

Ergo simplifying the production line and design requirements.

And if the A & B model happen to get better handling, manuevering, and more gas because of it, wouldn't that be better in general?

I'd imagine that weight would become a problem with both the A and B if you incorporated the larger wing. Since the B needs to land vertically, it's doubtful the designers thought that the extra control at low air speeds was worth the extra weight of an expanded wingspan.

With the A, having to reinforce a wing that size to the point where it could withstand 9G+ would have probably added quite a bit of weight to the plane as well. Keep in mind all variants are rubbing right up against the maximum weight spec, so there isn't a lot of wiggle room to play around with.

Just my $.02.


You're probably right, that makes sense.
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 23305
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post12 Jun 2014, 09:29

As you asked the question here and not at the other place then I'll answer it here. The bumpy runway 26/08 was not the problem although the last bits caused issues when the macadam veered up at both ends. For landing 08 was seldom used because the glideslope was parallel to the ground falling below it to threshold - it could not be used for instrument landings or FCLP.

The approach to RW 26 was odd due to the runway threshold first 1,000 feet sloping down, to then more or less flatten, to then start rising again so that the 'landing picture' created an illusion. We could ignore that by using the portable mirror usually sited at the duty runway. The downdraught due to the deep gully before the beginning of RW 26 was ever present though, just to keep us on our toes. However the excellent A4G power response (replicated by all accounts in the F-35C which just leaps up into a wave off) nullified the down effect; whilst the Macchi had a good engine control unit. My early year or two was with the Vampire which had only my left hand to control engine acceleration, which engine accel was very slow. The Sea Venom had a rudimentary engine control unit - a necessity for any carrier aircraft jet engine to get the maximum out of the engine for wave off performance (to give it a name). Nevertheless a couple of Sea Venom crews died at the end of RW 26. R.I.P.
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
Offline

Code3

Active Member

Active Member

  • Posts: 117
  • Joined: 11 Jul 2008, 02:45

Unread post12 Jun 2014, 15:03

The C-model needs to fold its wings to lower its footprint on carriers. This fold necessitates a split in the control surface. This split is likely not optimal, for numerous reasons. The most important is likely a negative impact on stealth due to the seam, something that's never good for RCS.

As for why the other two models don't use the C's wings: because it's not an optimal wing design for combat, but instead a compromise between combat performance and required lift for carrier ops. Increased lift = increased drag. The C-model is limited to 7Gs, and likely bleeds energy much quicker than the A/B models due to the increased wing surface.
Offline
User avatar

linkomart

Senior member

Senior member

  • Posts: 406
  • Joined: 31 May 2010, 07:30
  • Location: Sweden

Unread post12 Jun 2014, 15:09

KamenRiderBlade wrote:Any clue as to why they designed the F-35A / F-35B to have only Flaperons?

With the folding wing on the F-35C, it seems easy to implement the Flaperons & Ailerons

Makes you wonder if just using the F-35C wing as the standard wing across all 3 models would've reduced overall cost and design issues?


Those who know won't tell and those who don't....
So I'll tell you. :)
When you deflect the flaperon on the trailing edge of the wing, it deflects the airstream down, giving increased lift to the wing.
When you raise the flaperon on the trailing edge of the wing, it deflects the airstream upwards, giving decreased lift to the wing.
But, if you have a tailsurface behind the deflected flaperon it will see a change in angle of attack to the surrounding air, reducing the increace in lift, or in worst case altogether cancelling it out.
Same but reverse for raised flaperon.

Most probably the span of the tail is too large compared to the span of the wing (on A and B) to make the flaperon effective in roll. Therefore the tailerons are used for roll control. On the C however the ailerons are enough separated from the tail to make then efficient.
This is my best guess, you really need to do some CFD or wind tunnel test to really know, but as a rule of thumb it works this way.

my 5 cent
Attachments
klaff.jpg
Offline
User avatar

KamenRiderBlade

Elite 2K

Elite 2K

  • Posts: 2635
  • Joined: 24 Nov 2012, 02:20
  • Location: USA

Unread post12 Jun 2014, 15:32

linkomart wrote:
KamenRiderBlade wrote:Any clue as to why they designed the F-35A / F-35B to have only Flaperons?

With the folding wing on the F-35C, it seems easy to implement the Flaperons & Ailerons

Makes you wonder if just using the F-35C wing as the standard wing across all 3 models would've reduced overall cost and design issues?


Those who know won't tell and those who don't....
So I'll tell you. :)
When you deflect the flaperon on the trailing edge of the wing, it deflects the airstream down, giving increased lift to the wing.
When you raise the flaperon on the trailing edge of the wing, it deflects the airstream upwards, giving decreased lift to the wing.
But, if you have a tailsurface behind the deflected flaperon it will see a change in angle of attack to the surrounding air, reducing the increace in lift, or in worst case altogether cancelling it out.
Same but reverse for raised flaperon.

Most probably the span of the tail is too large compared to the span of the wing (on A and B) to make the flaperon effective in roll. Therefore the tailerons are used for roll control. On the C however the ailerons are enough separated from the tail to make then efficient.
This is my best guess, you really need to do some CFD or wind tunnel test to really know, but as a rule of thumb it works this way.

my 5 cent


Maybe a combo of Flaperon + Taileron + Leading Edge Slats are used simultaneously?
Offline
User avatar

linkomart

Senior member

Senior member

  • Posts: 406
  • Joined: 31 May 2010, 07:30
  • Location: Sweden

Unread post12 Jun 2014, 19:58

When you have a flight computer the control surfaces are always in the ideal position for the current flight profile, so yes, you do use a combination of control surface deflections all the time.

Usually, (IMHE) wind tunnel tests (or CFD calculations) gives the optimum settings for roll, pitch up, cruise etc at different q, alfa etc and this is fed in to the flight computer to give the optimum performance out of the airplane

Image
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 23305
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post12 Jun 2014, 20:37

Without the F-35C test pilot talking about IDLC here are the clips of the C doing FCLP with plenty of flapadoodle action.

PLAY> Right Click on Video>ZOOM>Full Screen Select
Attachments

F-35CflaperonIDLCclips.wmv [ 2.95 MiB | Viewed 10649 times ]

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

spazsinbad

Elite 5K

Elite 5K

  • Posts: 23305
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post12 Jun 2014, 22:19

Video above now on Utube:

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

KamenRiderBlade

Elite 2K

Elite 2K

  • Posts: 2635
  • Joined: 24 Nov 2012, 02:20
  • Location: USA

Unread post13 Jun 2014, 00:59

spazsinbad wrote:Video above now on Utube:



Just watched it, the Flaperon, Aileron, and Taileron were all working in conjunction with the Leading Edge Flaps that were bent downwards.

It's such a beautiful sight to watch it in action.

That just makes me love the F-35C more than the A/B variants.

=D

The future of flight for all high tech aircraft is where the computer controls all the flight surfaces and the user only needs to worry about what Yaw, Roll, Pitch, and engine thrust setting he's controlling.

Maybe add in a Angle of Attack hat switch to make it easier to veer off the normal forward vector.

Once the computer figures out all that info, it can make all pilots lives that much easier
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 23305
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post13 Jun 2014, 01:55

Heheh. Nope the dope on a rope (pilot on glideslope) in the cockpit does not need to worry about the frottle in the F-35C. All AUTO. Just the stick to keep 'meatball, lineup and airspeed' (optimum angle of attack). Not sure now if the 'auto throttle' is mentioned in the talkie video but I'll get some text. The LSOs writing in the now not available LSO Monthly Mag'n predict that completely auto landings will be the norm once the legacy aircraft except the Super Hornet and F-35C with the auto landing gear for / with JPALS is installed / enabled. Depending the AoA will be auto also so just the stick to ensure someone is in charge but auto JPALS will be centimetre accurate. Just look at the X-47B and she does not know whether it is day or night (always nite I guess). :devil:

A long shot may be that the IFLOLS (mirror) is replaced by the Bedford Array or used in conjuction with IFLOLS (for legacy aircraft such as Prop COD) but I'm no good at prediction for the USN or even anyone else. There are threads about these issues so searching on 'Bedford' will find stuff.
Flight control software to help pilots stick landings aboard carrier decks
20 Oct 2011 Office of Naval Research

“Select pilots in early 2012 will commence testing new flight control software, funded in part by the Office of Naval Research (ONR), intended to facilitate aircraft landings on Navy carrier decks with unprecedented accuracy. "The precision that we can bring to carrier landings in the future will be substantial," said Michael Deitchman, deputy chief of naval research for naval air warfare and weapons. "The flight control algorithm has the potential to alter the next 50 years of how pilots land on carrier decks." Navy and Marine Corps aviators conducting carrier landings today line up with a moving flight deck in a complicated process. They must constantly adjust their speed and manipulate the aircraft's flight control surfaces — ailerons, rudders and elevators — to maintain the proper glide path and alignment to the flight deck for an arrested landing. Throughout their approach, pilots eye a set of lights — known as the fresnel lens — located on the left side of the ship. It signals whether they are coming in too high or too low.

The new algorithm embedded in the flight control software augments the landing approach. Coupled with an experimental shipboard light system called a Bedford Array and accompanying cockpit heads-up display symbols, the software ties the movement of the pilot's control stick directly to the aircraft's flight path. Instead of constantly adjusting the plane's trajectory indirectly through attitude changes, the pilot maneuvers the aircraft to project a dotted green line in the heads-up display over a target light shining in the landing area....

...If the tests are successful, the software could be integrated aboard current and future aircraft to change the way carrier-based aviators have landed aboard ships for more than half a century — controlled crash landings. Increasing the precision of landings will boost pilot safety and reduce training requirements necessary to perfect carrier-landing skills. It could lower aircraft life cycle costs by reducing maintenance and avoiding repairs caused by hard landings.”

Source: http://www.physorg.com/news/2011-10-fli ... decks.html

Navy F-35C Prepares for Ship Trials, Faces Headwinds
17 Feb 2014 Sandra I. Erwin

"...One of the most anticipated features of the F-35C is an automated landing system called “delta flight path” that would take the pressure off aviators to nail landings on moving ships. “The delta flight path for the F-35C will make carrier landing so easy,” Burks says. “It will be a new era of carrier aviation. … Night landings will not be the number one task to focus on.” The system has been tested ashore but has yet to be tried at sea....”

Source: http://www.nationaldefensemagazine.org/ ... a2&ID=1415

F-35 Flight Testing At Pax
Eric Hehs 15 Oct 2012

"...The C-model is as solid as a rock [in landing config] and pilots land at a much slower speed—high 120s to low 130s [knots]. The angle of attack for landing is much lower in the C‑model so the pilot can see over the nose. The angle of attack control is very precise.”..." [AoA needs to be that]

Source: http://www.codeonemagazine.com/f35_arti ... tem_id=110

Naval Aviation Vision 2014-2025

“...Magic Carpet: Magic Carpet is an acronym for Maritime Augmented Guidance with Integrated Controls for Carrier Approach and Recovery Precision Enabling Technologies. It is a cockpit system that makes carrier approaches and landings easier and safer for Navy and Marine Corps pilots by reducing the vulnerabilities associated with fully-automated systems that are susceptible to jamming, poor reliability, and electronic failure. Magic Carpet’s integrated direct lift improves short-term flightpath response, which is critical to final glide slope corrections prior to landing. This system is currently flown in the F-35C and being retrofitted for testing in the F/A-18E/F. The potential cost-saving impacts of Magic Carpet are significant. Millions of dollars are spent yearly on landing practices ashore and actual carrier qualifications while underway. The money saved could be repurposed to train pilots to employ the weapon systems of their aircraft, dramatically changing their priorities from landing proficiency to warfighting proficiency. Conservative estimates indicate that Magic Carpet could save tens of millions of dollars per year, which include reducing the maintenance and repairs after hard landings aboard ship....”

Source: http://www.scribd.com/doc/218758281/Nav ... n#download

F-35C Integrated Direct Lift Control: How It Works - IDLC will make carrier approaches easier
Eric Tegler on October 9, 2012

"...IDLC’s job is to quickly help the pilot make glide slope adjustments during the carrier approach, Buus explains. It is resident within all three F-35 variants, not just the C model.

“What provides a huge benefit to the pilot is that [IDLC] moves the trailing edge flaps up or down to increase or decrease lift, which gives the airplane a very precise glide path control. It almost feels like a predictive control because it happens so quickly and you can get such effective changes in glide path. The trailing edge flaps are pretty large on the F-35C. For a carrier approach we nominally set them to 15 degrees trailing edge down, which is a half-flap configuration. So there’s room for the flaps to come down and to come up and either increase or decrease lift.”

In essence, one could call IDLC “automatic flap response.” Its effect is to literally “heave” the airplane in the vertical axis, Buus says.

“The F-35C is designed to be an auto-throttle flyer on approach. So the pilot will engage auto-throttles and then he just has to fly glide path and lineup with the stick. When he makes pitch-stick inputs to control the glide slope – if he pulls back on the stick a little – the airplane will respond by lowering the flaps to increase lift. The seat-of-the-pants feel is a lot more in the vertical axis. It actually changes the G-level of the airplane; as the flaps come down, they add lift, increasing G and vice versa.”

The pilot is indirectly flying the flaps with the stick, Buus says. From the cockpit, IDLC gives the F-35C exaggerated throttle/pitch response, the test pilot affirms. “It’s almost immediate. It takes longer to make the correction in legacy airplanes.”...

...In a few years the F-35C’s flight control system will pair with the Joint Precision Approach and Landing System (JPALS) to enable data-linked approaches controlled from the carrier. IDLC will take relevant incoming data from the flight control computer and aid in making the process that much more precise...."

Source: http://www.defensemedianetwork.com/stor ... -it-works/
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
Next

Return to F-35 Design & Construction

Who is online

Users browsing this forum: No registered users and 1 guest