F-35 Approach AOA

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Unread post09 Jun 2010, 15:19

Salute!

Looks like the "C" will be a very smooth transition.

I would not be surprised to see the "C" be bought by more air forces than the "A". Kinda like the SLUF. When USAF went with the A-7, they put in the newer motor and drastically improved the avionics. Then the Navy saw the "D", and bought them for themselves as the "E". Virtually identical except for the nose gear.

The over-the-nose vis and the approach speed is very important, and I was surprised at the Navy spec for 145 knots. If the boat is at 25 or 30 knots, and we have 10 or 15 knots of wind, then we're talking approach to the deck of 100 knots or less. Not too shabby. I doubt that many Navy jets will be at the 145 approach IAS.

The larger wing area of the "C" might hurt top speed, but I bet that sucker has better range than the "A". And trust me, the Hornet is neat, but the sucker burns gas like the F-4. Too much for the loadout and such.

Looks like we actually "turned the corner" with this new jet.

Gums sends ...
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Unread post09 Jun 2010, 21:43

gums, the limit for Optimum AoA approach airspeed is a limit of the arrestor gear weight/airspeed. In this instance the aircraft is designed to the ship limit. Perhaps new fangled arrestor gear (similar to variable launch of EMALS) will allow different specifications but as indicated in this PDF sometimes the ship wins: http://handle.dtic.mil/100.2/ADA399988 [1Mb] "The Influence of Ship Configuration on the Design of the Joint Strike Fighter"

The worst case scenario is relevant for example: nil wind (or even a slight downwind during landing) at max landing weight optimum angle of attack recovery. In ordinary carrier ops sometimes the carrier may not be able to go fast in a slight wind due to nearby land for example. And yes range is greater with bigger wing and turning radius much better (vague recollection - mentioned elsewhere).
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Unread post09 Jun 2010, 22:46

Salute!

I don't get it, Spaz.

I can't find a limit on the cables versus the jet's AoA on approcah, or speed. I'll read the reference again.

Looks to me that the sucker has good over-the-nose vis for the pilot at "normal" approach AoA's. Maybe like the SLUF. Less tinkering with the control surfaces such as the Hornet required ( canted rudders to get the nose up for takeoff).

i also note that the AoA they are talking about in your reference is not the aircraft's aero AoA but its fight path vector with respect to the local level.

This jet looks like it will have a very easy carrier qual series. Great vis and a decent approach speed.

The existing cables and their capabilities don't seem to be a factor. Biggest speed requirement has always been "wind over the deck" for takeoff. If we have a 145 knot landing speed limit, then no problem for the "C".

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Unread post09 Jun 2010, 23:56

Gums, probably more PDF reading, such as an LSO NATOPS manual will be informative also: http://www.vaw120.navy.mil/NATOPS/UE_In ... NATOPS.pdf (probably this link not working now so try next [older one but still relevant]) http://www.robertheffley.com/docs/CV_en ... NATOPS.pdf (4Mb)

Carrier Landing Aircraft require special features that are 'hinted' at in the aforementioned 'JSF Design' PDF above (see graphic). Another thread has info about the arrestor gear capabilities mentioned (see graphics) from this thread: http://www.f-16.net/f-16_forum_viewtopi ... rt-75.html

Image
Image

Bear in mind the JSF pilot can see through the aircraft (perhaps a feature not realised when the PDF was written). In any event as you say good physical visibility forward is required. I'm not in the JSF program so I can only guess from public knowledge about a lot of things that likely will be revealed when the F-35C is doing FCLP and DLP trials. Therefore I cannot state categorically that the carrier JSF will be like all other USN jets but in a nutshell they all fly a constant Optimum Angle of Attack down the glideslope to a no flare landing either ashore or afloat. IF USAF former USN aircraft used a different airfield landing technique - then that is unknown to me. AFAIK the Oz Hornets land Navy style ashore.
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Unread post10 Jun 2010, 00:10

Not being a pilot this will be an educated guess from my side, but the larger wing area allows the plane to descend with the same rate and AoA, while 20-25 knots slower airspeed, compared to the A model. Since they typically slam it down on the carrier deck they can lower the AoA, increase the descend rate, while keeping the throtle at a lower setting to maintain the lower maximum speed required. I would think the B model would have a slightly different modeling in the FLCS due to the heavy lift fan, where the other two may have a close to empty fuel tank.
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Unread post10 Jun 2010, 00:26

lamoey, for the moment we have to guess about a lot of things about JSF and variants. Generically the Optimum Angle of Attack has the aircraft landing hook first, then main wheels then nose gear. As the hook engages the wire (or cross deck pendant as USN want to call it) the deceleration brings everything down. There is a maximum rate of descent which when exceeded can break the strong undercarriage. However the medium ROD is usual so that ship movement and last second pilot YIPS can be accounted for so as to not exceed the MAX ROD. Using this ideal aircraft attitude gained by the Optimum Angle of Attack the best carrier landing can be carried out. Bear in mind under the maximum carrier landing All Up Weight, the KIAS will vary with weight whereas the AoA Optimum remains the same. The LSO looks at that OAoA Attitude to gauge how the approaching aircraft is 'travelling' down the glideslope. Using a different approach flying technique a carrier pilot maintains glideslope with power while the nose controls AoA (airspeed). The only way to FLY NAVY! :D

There is nothing smooth about a carrier landing except that perceived from the outside. Inside the pilot is working like a 'one armed wallpaper hanger' with the engine(s) cycling up and down and nose moving also to maintain the ideal attitude/glideslope all the way to touchdown/arrest.
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Unread post10 Jun 2010, 02:47

Salute!

I still see no show-stoppers with respect to the boat's arresting gear, nor none with the cats.

The USAF A-7's usually did a very slight "flare" to get a better "touch", but we flew the indexer just like the Nasal Radiators did.

Only time I ever seriously "planted" the sucker without a flare was with a hydraulic failure when I had to take the approach cable. We had same main gear as the Navy jet, and nose gear was "almost " the same, but didn't have the gizmo for the cat shot. in really bad weather, some of us would "plant" the thing, but I am talking 1/8 of a mile vis and 50 or 100 feet ceiling. Ever done one of those, Spaz? And, BTW, I did one in the VooDoo at 180 KIAS approach speed one day. Interesting, to say the least.

Unless the "C" bounces on the deck, or has a hook angle problem, the sucker looks like it will have a very smooth carrier qual series of flights.

Gums sends ...
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Unread post10 Jun 2010, 03:43

Gums, thanks for the USAF/navy style landing explaino. I'm not contradicting (aircraft type would be significant also) but of course as the first PDF explains about Navy requirements for a 'flare' (if we can call it that for this explanation purpose) during the approach (apparently new research has made this requirement obsolete - so perhaps no longer relevant).

"(2) the aircraft must be capable, without changing engine thrust, of effecting a change in flight trajectory that intersects a glidepath positioned 50 ft above and parallel to the aircraft's glidepath at the start of the maneuver, within 5 sec of control application;"

Anyway at Opt AoA there is little energy for a proper 'float flare to greaser' landing but enough for that 'cushion effect'. Usually Navy Pilots will practise same landing technique (with a mirror if available ashore) or otherwise 'wing it' on a non-Naval airfield.

In my time (now more than 35 years ago) only GCA/CCA could bring one down to 1/4 NM at 200 feet. Otherwise only TACAN or a Radio Beacon approaches available. I have in real weather started to overshoot at what was my authorised minima [at that time] of 1/2NM at 400 feet AGL off a GCA to then spot a magic hole in the clag straight ahead with good sight of the runway so I did a "High Precautionary Approach" style descent (with power off) to a 'full power coming on to cushion the huge descent rate' landing [with power back to idle instantly] on the runway (was already cleared to land off the GCA). Outsider viewers thought it was spectacular. :D Other than that had a nice escape here: http://www.filefront.com/12844254/RampS ... ryA4G.pdf/ (7.5Mb)
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Unread post10 Jun 2010, 05:20

Salute!

Sounds great Spaz, but had trouble with the link.

As you have pointed out, we USAF pukes tried for a smoother touch and the nasal radiators landed pretty much the same way on a long runway as on the Nimitz. The F-4 guys were pretty much the same as us, but seems that many used the "navy" technique. No big deal, and it is comforting to have a jet that you can "plant" without worrying about cracking the wing box or damaging the gear.

May surprise you, but i landed the Viper about like the SLUF. Flew the "optimum" AoA and did only a slight flare. That plane likes to land slow, so all the flare and such just seemed harder than a mini-flare just at touchdown.

I see no problems with the F-35C, and I hope you don't. I see a plane that will adapt to carrier ops much easier than the Hornet, aka YF-17.

Unlike the Hornet, the F-35 was designed from the get-go for the Naval version and the USAF/USMC versions. The plane is significantly different than the F-111 ( read ATF) back in the 60's. The thing reminds me of the SLUF and the Double-Ugly more than the Hornet. Many, many mods to the YF-17 to get to the Hornet. And it showed.


Gums sends ...

P.S. BTW, my poor vis landing in the VooDoo was at New Orleans NAS on a GCA with a calm, old Chief talking me down. Unlike the USAF controllers, he continued to talk to me even as I reached the min alt decision point. As I advanced the throttles for the go-around I saw the lights at the end of the runway and chopped power, touched, deployed drag chute and aero braked. Thanks God, and Chief, I'll take over from here, heh heh.
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Unread post10 Jun 2010, 10:19

Gums, thanks for explanations. Firstly not sure if you were able to download the 'rampstrike' PDF story. Same version has been made available here: www.a4ghistory.com but not yet visible on the page. If you right button mouse click on this next link you will be able to 'save as' the 7.5Mb PDF to your computer (that is the plan anyway): www.a4ghistory.com/Ramp-Strike-01-Sept-71-no8.pdf

Ashore our ATC GCA chaps (in a portable van control space with a separate portable radar) would continue to talk advisory only at minima and after. When carrier landing at night they would stop at the 1nm mark to allow us to concentrate (to look ahead and land visually) and also 'call the ball' to the LSO (often more wish than reality but it got better the closer one got to the mirror).

At NAS Nowra the two runways were only 6,000 feet, the minimum for A4G ops; where braking on a wet runway was always critical. However one gets used to these things. Max weight takeoffs on hot windless summer days could be dicey to say the least. :D

Yes to me it seems the JSF/F-35 will be a great aircraft to fly (especially the STOVL version from what we have seen already). I'm just impatient to know more practical details for carrier landing - these will be known soon enough.
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Unread post10 Jun 2010, 11:44

From the DEWLINE comes this item which elaborates on some issues mentioned above:

http://www.flightglobal.com/blogs/the-d ... e-aud.html

F-35C first flight and the audacity of naval aviation By Stephen Trimble on June 9, 2010

"...Last year's discovery that the F-35C requires a keel redesign to survive repeated carrier landings may indicate the scale of the learning curve, even though the company is no stranger to carrier-based aviation with the S-3 Viking.

I recommend a new article in the Naval War College Review to gain a better appreciation for the story of carrier-based aviation. The author, Robert C. Rubel, argues the Navy's carriers didn't fully recover from the transition to the jet age until the arrival of the F/A-18 Hornet. An excerpt:

"Some histories of naval aviation regard the transition to jets to be substantially complete with the phasing out of the last propeller driven fighter, the F4U Corsair, while others maintain that the transition lasted until the introduction of the F-8 Crusader and F-4 Phantom II--the first Navy carrier-based fighters that were the equals of their land-based counterparts. Another way of looking at it is through the lens of safety: one might declare the transition to have been complete when the Navy aviation accident rate became comparable to that of the U.S. Air Force. The logic behind this reasoning is that whereas a multitude of factors--technical, organizational, and cultural--constitute the capability to operate swept-wing jets, the mishap rate offers an overall indicator of how successful an organization is in adopting a new technology.

Using this criterion, the Navy's transition process lasted until the late 1980s--which was, not coincidentally, the era in which the F/A-18 arrived in the fleet in numbers. This article argues that tactical jet aircraft design and technology presented Navy aircrews, maintenance personnel, and leaders with several major challenges that were in fact not substantially overcome until the introduction of the F/A-18 Hornet in 1983."


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Unread post10 Jun 2010, 11:53

Another LSO NATOP manual (2001 version) is here: http://www.navyair.com/LSO_NATOPS_Manual.pdf (0.7Mb)

A graphic showing improvement in USN accident rate over time (biggest influence would have been standardisation by NATOPS) from 'GRAMPAW PETTIBONE' follows.
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Unread post10 Jun 2010, 17:48

Gums wrote:Salute!

Sounds great Spaz, but had trouble with the link.

As you have pointed out, we USAF pukes tried for a smoother touch and the nasal radiators landed pretty much the same way on a long runway as on the Nimitz. The F-4 guys were pretty much the same as us, but seems that many used the "navy" technique. No big deal, and it is comforting to have a jet that you can "plant" without worrying about cracking the wing box or damaging the gear.

May surprise you, but i landed the Viper about like the SLUF. Flew the "optimum" AoA and did only a slight flare. That plane likes to land slow, so all the flare and such just seemed harder than a mini-flare just at touchdown.

I see no problems with the F-35C, and I hope you don't. I see a plane that will adapt to carrier ops much easier than the Hornet, aka YF-17.

Unlike the Hornet, the F-35 was designed from the get-go for the Naval version and the USAF/USMC versions. The plane is significantly different than the F-111 ( read ATF) back in the 60's. The thing reminds me of the SLUF and the Double-Ugly more than the Hornet. Many, many mods to the YF-17 to get to the Hornet. And it showed.


Gums sends ...

P.S. BTW, my poor vis landing in the VooDoo was at New Orleans NAS on a GCA with a calm, old Chief talking me down. Unlike the USAF controllers, he continued to talk to me even as I reached the min alt decision point. As I advanced the throttles for the go-around I saw the lights at the end of the runway and chopped power, touched, deployed drag chute and aero braked. Thanks God, and Chief, I'll take over from here, heh heh.


I think the difference here is that the Navy and the Air Force are mostly on the same page.

For the TFX program, the Navy and Air Force were on completely different pages with completely different needs. The Air Force wanted a bomber. The Navy wanted a fighter and the air force designed the jet to their needs.

With LWF/VFAX, the Air Force and Navy weren't really on the same page either. The Air Force wanted a lightweight fighter. The Navy needed something that could replace the a-7 in the air to ground role while replacing some of what the phantoms did in the air to air role in the Marine squadrons and the air wings on the midway class ships which were too small for tomcats. Neither was a priority for the Air Force, nor was actually being able to land on a carrier and once again they choose only based on their requirements. Later on, the F-16 would be modified for AtoG and BVR roles and gain about 3500lbs in the process.

With the JSF, its a little more consistent on the requirements. The Air Force and the NAVAIR community are looking for a lot more of the same requirements.
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Unread post10 Jun 2010, 17:53

Salute! Aye aye!

I get the impression that the nasal radiator writing for the Navy journal was a Hornet dweeb, heh heh.

Seems to this old fart that the Double Ugly was designed for fleet air defense and carrier ops from the get go, so I question the author's assertion that the Hornet set a new standard. I also remember the Panther, Cougar, Tiger and, of course, the Scooter. Somewhere in there we also had the Skyray - semi-delta wing interceptor with a good Pratt motor and afterburner.

The YF-17 required many changes to be capable of cvarrier ops, and GD flat-ass quit when asked about a carrier version of the YF-16. Wasn't the spec that GD had designed the LWF for, and they used their resources to improve the design and produce the Viper I first flew back in 1979. Except for no relief tube and a crappy autopilot, they did a fine job, IMHO.

I am surprised at the Crusader loss rate and will have to verify. Only other jet I know of with that loss rate was the Thud, and seems most of them were no sierra combat losses. have many classmates that punched out and spent time in the Hilton.

So LTV used the Crusader's best features and developed the SLUF. Designed for carrier ops from the beginning, and was operational by late 60's, 20 years before the Hornet. Sucker lands real easy on the boats, and the cat shots were also real easy on the boat's gear as well as the SLUF's nose gear. Honest, I LOVED THAT PLANE!!!!!


I can't find a good reference to a re-design of the F-35 "keel" to withstand repeated arrestments. No surprise there, and I would have thot LM had thot about this beforehand. Hmmmm......

I am still not worried in the least. The Hornet required a lot more re-design than the F-35C. Other than the Double Ugly, this new jet may be the best multi-service plane we have ever seen. While I don't like the program stretchout, we all must realize that this may be the last human-operated jet we shall ever see. Just think about that.

We must also remember that GD got the JTF contract back under McNamara. The final operational use of the jet was decent, but the Naval variant was a disaster fro the beginning. many of we nuggets had serious concerns about the beast, but it was way above our pay grade. So we witnessed the genesis of the "fighter mafia" on the Air Staff. Also saw the Navy get serious and develop the F-14. Then the Eagle, and finally the low-end complement to the Eagle - the Viper.

I was privileged to be there as USAF and USN and USMC got their act together and field some really capable jets that have served us for three decades.

Gotta go, and I hope that my "historical" perspective adds to the flavor of this neat forum. Throw some more shrimp into that gumbo, huh?

Gums sends ....

P.S. I had never flown a GCA with a Navy controller until that day in early 1967 at Belle Chase. So I was pleasantly surprised when that crusty old Chief kept talking to me once I neared decision height. he gave me a few "attaboys" on the approach, and he was also surprised at my groundspeed. Figure it out - basic approach was 175 IAS plus 5 knots for every 1000 pounds above 3,000. Only good thing about that jet was if you had it lined really well from a few miles out, then you couldn't do much to screw it up.
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Unread post22 Oct 2010, 07:30

F-35C carrier approach info: VX-23 'Salty Dogs' Joint Strike Fighter Update -LCDR Ken “Stubby” Sterbenz VX-23 Ship Suitability Department Head in Paddles Monthly - Sept 2010

http://www.hrana.org/documents/PaddlesM ... er2010.pdf (1.3Mb)

"The F-35C is 51.5 ft long and has a wingspan of 43 ft and 668 ft2 of wing area (7 ft longer wingspan and 208ft2 more wing area than the Air force or Marine versions.) It also carries 19,800 lbs of internal fuel - 1000 pounds more gas then the Air Force version. It is powered by a Pratt and Whitney F135 engine that produces 28k lbs and 43k lb of thrust in MIL and AB respectively. The max trap weight will be around 46k lbs, with an empty weight of about 35k lbs. It will fly an on-speed AOA of 12.3° at 135-140 KCAS [Optimum Angle of Attack or Donut]. Due to the fact that flap scheduling is completely automatic, the cockpit was designed without a flaps switch. Additionally, the tail hook retracts into the fuselage and is covered by hook doors that have an as-yet-to-be-determined airspeed limitation..." LT. Dan "Butters" Radocaj - VX-23 Ship Suitability
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