Possibility small STOVL carrier USN/USMC

Discuss the F-35 Lightning II
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spazsinbad

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Unread post16 Feb 2010, 19:49

How USMC will deal with JSF-B heat issues:

Interim Technical Guidance (ITG 2010-01) Maintenance Hangar Design & Planning Guidance for F-35B or C:

http://www.wbdg.org/ccb/NAVFAC/INTCRIT/fy10_01.pdf (0.247Mb)

For USMC:
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Unread post18 Feb 2010, 12:56

http://www.scribd.com/doc/27000495/Bullhorn-64-8feb10 (1Mb PDF)

Pentagon Report
The issue wasn’t disclosed in Gilmore’s annual’s report released last week. That report said F-35 testing so far raised concerns that engine blasts from the carrier model and Marine Corps short-takeoff and vertical-landing versions could cause deck damage and injure personnel.
The F-35 is the Pentagon’s largest weapons program. The fiscal 2011 defense budget set for release Feb. 1 requests 42 fighters, up from 30 this year. As many as 20 jets are Navy and Marine Corp versions.
Kent said all design changes to strengthen the center fuselage will be incorporated before parts are made for the first production F-35Cs in the fourth initial production contract now under negotiation for 30 aircraft.
This is only a development-phase issue “and a minor one at that,” Kent said. “This is part of our normal airframe development process, and is not a concern for the Navy.”
Cheryl Limrick, a spokesman for F-35 military program manager Marine Corp. Major General David Heinz, didn’t return an e-mail seeking comment today.
The Navy plans to buy as many as 680 carrier and short-take- off versions of 2,456 planned jets.
Deck Damage
The Pentagon’s Gilmore said in his report that the engine and power-systems’ exhaust on the Navy and Marine versions is powerful enough to pose a threat to carrier personnel. The blasts also may damage shields used to deflect heat on the deck, including on the CVN-21 carrier, the Navy’s most expensive warship.
“Early analyses of findings indicate that integration of the F-35 into the CVN-21 will result in damage to the carrier deck environment and will adversely affect hangar deck operations,” Gilmore wrote.
The Navy model’s exhaust area is larger than the Boeing planes’, making the jet-blast deflectors used during launch “vulnerable to warping and failure,” he wrote.
Exhaust from the Marine Corp version’s integrated power system deflect downward and may be “a hazard to flight deck refueling, munitions, personnel and equipment” located on catwalks, the report said.
Lockheed spokesman Chris Giesel said tests conducted with the JSF Program Office and the Navy “are showing positive results regarding compatibility of the F-35’s exhaust with carrier decks and tarmac surfaces. The study will conclude in spring 2010.
Justin Fishel
- FOXNews.com
- February 01, 2010
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Unread post02 Mar 2010, 22:07

Spanish & RAN LHD eye candy cutaway (with Harriers) you can imagine the F-35Bs...
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Unread post05 Mar 2010, 19:16

Earlier a mention was made of USN testing of 'Ski Jumps' for USN aircraft. Here is a USN Hornet 'jumping for joy' - what else? :lol:
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Unread post06 Mar 2010, 05:51

spazsinbad wrote:Spanish & RAN LHD eye candy cutaway (with Harriers) you can imagine the F-35Bs...


IMHO, USN should outsource at least 50% of her future ship selection contracts to either Spanish or Turkish naval building (of whatever type or model). They seemingly know how to both conceive of modern ship designs and then build them, at a reasonable price. Highest respects to LM and GD.
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Unread post09 Mar 2010, 22:03

F-35 sim demonstrator says that the nozzle goes to 103 degrees during decelleration inflight to hover. Then later shows the thrust vector at 90 degrees. This info included for those wondering about 'reverse thrust' for SRVL landing for example: http://www.patricksaviation.com/videos/perabrown/4344 (48Mb .MP4 video)
RAN FAA A4G: http://tinyurl.com/ctfwb3t http://tinyurl.com/ccmlenr http://www.youtube.com/user/bengello/videos
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Unread post10 Mar 2010, 04:44

geogen wrote:
spazsinbad wrote:Spanish & RAN LHD eye candy cutaway (with Harriers) you can imagine the F-35Bs...


IMHO, USN should outsource at least 50% of her future ship selection contracts to either Spanish or Turkish naval building (of whatever type or model). They seemingly know how to both conceive of modern ship designs and then build them, at a reasonable price. Highest respects to LM and GD.



Like the US can afford to export more work overseas! :roll:
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Unread post10 Mar 2010, 05:23

geogen wrote:
spazsinbad wrote:Spanish & RAN LHD eye candy cutaway (with Harriers) you can imagine the F-35Bs...


IMHO, USN should outsource at least 50% of her future ship selection contracts to either Spanish or Turkish naval building (of whatever type or model). They seemingly know how to both conceive of modern ship designs and then build them, at a reasonable price. Highest respects to LM and GD.

I wouldn't make that decision based on some glossy sales brochures. There are very good reasons why our ship designs cost more. For instance, take a walk through a Meko frigate. Then take a walk through our OHP class ships. Then think about which one you would want to be in if it got hit.

In general, with a few exceptions, foreign designs are not as survivable. Nor are they as flexible. Most LHDs outside the US are designed for operations other than war and low intensity conflicts. Our ships can do all that and fight a real war.
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Unread post13 Mar 2010, 03:43

For the tinny foreign vessels at least the heat issue will not melt their deck candy:

http://www.defensenews.com/story.php?i= ... =AME&s=AIR

"We are very excited about the arrival of JSF," Marine Corps commandant Gen. James Conway said, while acknowledging development problems with the aircraft. "While we're hearing some somber things about the JSF, heat and noise [signatures] are in the general range of the legacy aircraft" the JSF will replace."

And some more info about the Olde Skie Jumpie Testing is added below:
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Unread post22 Mar 2010, 11:57

Date Posted: 11-Dec-2008 International Defence Review

http://militarynuts.com/index.php?showtopic=1507&st=120

Preparing for take-off: UK ramps up F-35 carrier integration effort

"A range of simulation, modelling, risk-reduction and technology-demonstration activities are under way to optimise the safety and operability of the ship/air interface between the UK's new aircraft carriers and the F-35B Joint Strike Fighters that will operate from them. Richard Scott reports

BAE Systems' lead test pilot Graham Tomlinson is at the controls of the F-35B Lightning II, the short take-off, vertical-landing (STOVL) variant of the Joint Strike Fighter (F-35). Up ahead he sees the wake, and then the large grey bulk, of HMS Queen Elizabeth, the first of the UK Royal Navy's (RN's) two new 65,000-tonne displacement Future Carrier (CVF) vessels.

Flying to Visual Flight Rules (VFR), Tomlinson is in a 'slot' designated by the ship's Flyco (Flying Control) as he prepares to recover to the carrier deck. Overflying the starboard side of Queen Elizabeth at an altitude of 600 ft in wingborne flight, he then banks the aircraft to roll out on a reciprocal heading (approximately 1.5 n miles abeam the ship) to perform the visual circuit.

Towards the end of the turn, having throttled back to bring the aircraft to a speed below 250 kt, Tomlinson presses a single switch on the right-hand sidestick controller to transition the F-35B to STOVL flight mode.

During conversion, the doors covering the lift fan and surrounding the three-bearing swivel duct automatically open and both propulsion effectors vector to an appropriate angle.

At the end of the conversion, the aircraft is configured for semi-jetborne flight. Tomlinson selects landing gear down in readiness for recovery.

He now initiates a final descending turn shortly after passing the stern of Queen Elizabeth, rolling out onto the same heading as the ship at a range of approximately 1.5 n miles. Using the glide slope and line-up cues provided by the ship's visual landing aids, together with helmet-mounted display symbology, the aircraft comes onto a three-degree decelerating approach before being brought to a stabilised hover, at the same forward speed as the carrier, alongside the designated deck landing spot.

Tomlinson now translates laterally, from abeam, to reposition his aircraft over the landing spot, using the longitudinal and lateral deck markings for line-up (the correct hover height is indicated by the Height Indicator and Hover Aid Thermometer [HIHAT] fixed to the forward island).

The aircraft descends vertically onto the flight deck and once safely on board Tomlinson is directed to taxi clear of the landing runway to a specified parking spot.

Of course, it will be some years before the F-35B - the UK's preferred choice to meet its Joint Combat Aircraft (JCA) requirement - commences first-of-class flying trials from Queen Elizabeth. Only a single F-35B development test aircraft (BF-1) has flown, and the first steel for Queen Elizabeth will not be cut until early 2009.

Even so, intensive work is already under way to de-risk the ship/air interface between CVF and JCA - notably the recovery manoeuvre and associated landing aids - through modelling, simulation, technology demonstration and risk reduction trials. In addition, wide-ranging studies have been performed to characterise, evaluate and define detailed aspects of the flight deck and aviation support infrastructure so as to optimise the safety and capability of the ship, aircraft and deck parties in what is a highly dynamic and potentially hazardous operating environment.

Management of the CVF/JCA ship/air interface is a joint endeavour between the Defence Equipment and Support organisation's JCA Integrated Project Team (IPT) and the CVF programme (delivered through the Aircraft Carrier Alliance [ACA]), with roles and responsibilities apportioned according to an internal business agreement. While the main human resource supporting this activity actually resides in the ACA, the JCA IPT holds the funding and is responsible for an integration contract flowed through to the Lockheed Martin-led Team F-35 via the US F-35 Program Office (JPO). The main rationale for this arrangement is that the JCA IPT already has a formal relationship with the JPO, whereas the ACA does not.

Commander Andy Lison, CVF Aviation Manager within the Ministry of Defence's (MoD's) Capital Ships Directorate, and today firmly embedded within the Aircraft Carrier Alliance (ACA), is conscious that the transition of the carrier programme from design to manufacture means that the time has come to take some critical decisions. "CVF will be the world's first big deck STOVL carrier, and the first ship to be designed around F-35," he points out, adding: "That presents us with both an opportunity and a challenge."

Touchpoint matrix
The opportunity comes from the ability to optimise the ship for the aircraft, while the challenge arises from the need to manage CVF and JCA vis-à-vis their development programmes and design maturity. Cdr Lison says: "While the aircraft and its accompanying operations and support architecture continue to iterate, we are at a point in the ship programme where we have to stop designing and start building. That demands that we closely manage the ship/air interface and attendant programme risks."

The primary mechanism to achieve this is through the integration contract. "We have developed a 'touchpoint' grid matrix to show where the ship needs data on the aircraft to inform its design," explains Cdr Lison. "What the integration contract enables us to do is to reach forward in the aircraft development programme and get visibility of those data elements that we need to understand the architecture of F-35 and its requirements relative to the ship. These considerations include cooling, power, bandwidth, acoustics, thermal effects, jetwash, logistics footprint, weapons and electromagnetic compatibility.

"We are now at a point in the carrier programme where we have, on a weekly basis, been 'nailing down' the detailed design of the ships. This means we will go with the data we have at each 'touchpoint' today, move forward with the ship, understand the interface, and quantify the residual risk according to how mature the data is."

The vertical recovery vignette previously described has already been 'flown' many times by F-35 test pilots in a high-fidelity simulation environment at BAE Systems' Motion Dome Simulator at Warton, Lancashire. Here, through the use of piloted simulation, a huge amount of qualitative and quantitative data has been gathered, in a safe and repeatable environment, to inform the CVF/JCA integration process well in advance of first-of-class testing and without the need to resort to costly physical mock-ups or flight trials.

Housed in a large-diameter dome, the simulator itself features a cockpit mounted on a six-axis motion platform, with a high resolution outside world image projected onto the dome's interior surface. This differs from conventional practice (where the cockpit is encapsulated inside a smaller dome mounted on top of a motion platform) so as to offer benefits in terms of a reduction in platform payload and corresponding increase in dynamic performance.

The cockpit has been modified to provide a field-of-view, from pilot eye-position, which is representative of the F-35B. Active side-stick and throttle units have also been installed; to the same design as will be used in the F-35 pilot training simulators. In most other respects the cockpit is generic (for example, the head-down multifunction displays are presented on three small LCD panels, rather than on a single large-format display as in the F-35).

Four Canon SXGA+ (1,400x1,050) liquid crystal on silicon projectors are used to project the 'outside world' onto the dome surface, with the image from each projector blended to produce a continuous field-of-view (220 degrees in azimuth by 50 degrees in elevation). Each graphics channel is rendered on a separate dual-processor PC using Nvidia GeForce 8800 GTX graphics hardware.

The outside world visuals are generated using a software application developed by the Simulation Group, interfacing with the Vega Prime Toolset. Vega Prime offers the capability to extend the tool through a series of application-specific 'plug-in' modules (such as a marine module used to generate a realistic seascape, including dynamic sea surface and water wakes).

A three-dimensional visual model of CVF was developed from general arrangement data supplied by the ACA. The level of detail incorporated in the ship model, which includes the location and characteristics of the deck markings and visual landing aids, is an important factor in creating a realistic and immersive cueing environment for the pilot. A number of static F-35Bs and Merlin helicopters have been positioned on the flight deck in a typical 'deck-park' arrangement.

As part of the baseline System Development and Demonstration (SDD) programme, a comprehensive non-linear simulation of the F-35B has been developed using the ATLAS (Analysis, Trim, Linearize and Simulate) tool developed by Lockheed Martin Aeronautics. To develop the real-time simulation, the various ATLAS subsystems have been reused via an interface wrapper.

Simulation success
The only modification to the original SDD simulation has been the addition of a CVF specific ship model. This mathematical model consists of a defined geometry (including deck layout and ski-jump ramp profile), a ship motion model to represent the sea-keeping characteristics of the vessel, and an air-wake model to capture the effects of the ship's structure on the flow field around and downwind of the vessel.

Speaking at the Royal Aeronautical Society's International Powered Lift Conference (IPLC 2008) in July 2008, BAE Systems' F-35B project test pilot Pete Wilson praised the simulation environment. "Legacy simulations were nowhere near good enough," he told delegates. "But the reality of the very high resolution environment created in the Motion Dome Simulator has surpassed both industry and customer expectations. That said, there is still some room for improvement, notably in the areas of air wake and weather."

A number of simulator trials have been 'flown' to date. In December 2007, work was undertaken to assess vertical landings and shipborne rolling vertical landings (SRVLs) so as to inform landing aid development. Investigations into the field of regard offered by the F-35's distributed aperture electro-optical sensor system were also carried out.

Further trials were performed in July 2008. These were predominantly SRVLs to further inform the VLA design process.

The MoD is acutely aware that the ability of the F-35B to meet JCA Key User Requirement (KUR) 4, which sets out a vertical recovery bring back threshold, remains in doubt. The UK requirement calls for a recovery in hot day conditions with a 4,080 lb payload (essentially two precision- guided bombs, two AIM-120 missiles and a fuel reserve). Current projections predict a performance shortfall of about 175 lb, although this could increase to 360 lb if only the US Marine Corps' less stressing Key Performance Parameter is delivered.

As a result, the MoD has been exploring the adoption of the SRVL manoeuvre - essentially a running landing onto the carrier deck - to improve bring-back performance. SRVL exploits the ability of the F-35B to use vectored thrust to slow the speed of the aircraft approach to about 35 kt of closure relative to the carrier (assuming a forward airspeed of 60 kt and 25 kt wind over deck) while still gaining the benefit of wingborne lift. This in turn offers the possibility of a significant increase (estimated at over 2,000 lb) in bring back compared to a vertical recovery. SRVL could also reduce propulsion system stress to increase operational flexibility and propulsion system life.

SRVL manoeuvre
As currently conceptualised, an aircraft executing an SRVL approach will follow a constant glidepath (five to six degrees) to the deck. This angle is about twice that of a normal CV approach, offering increased clearance over the stern and less touchdown scatter. The touchdown position on the axial flight deck is about 150 ft from the stern, similar to that of a conventional carrier.

No arrestor gear is required. Instead, the aircraft brakes are used to bring the aircraft to a stop.

Low-key studies to investigate the SRVL technique were initiated by the MoD in the late 1990s, but the work has latterly taken on a much higher profile after the MoD's Investments Approvals Board (IAB) in July 2006 directed that SRVL should be included in future development of the JCA design to mitigate the risk to KUR 4. Accordingly, the JCA IPT amended the CVF integration contract in mid-2008 to include this requirement.

Addressing IPLC 2008, Martin Rosa, F-35 technical coordinator in Dstl's air and weapon systems department, said the SRVL studies to date had shown "a way forward exists to achieving operationally useful increases in bring-back, compared to a vertical landing, on board CVF with an appropriate level of safety".

Dstl began early work to examine the feasibility of employing the SRVL manoeuvre in 1999. According to Rosa, an initial pre-feasibility investigation demonstrated the potential payoff of the manoeuvre in terms of increased bring back, but also threw up four key areas demanding further examination: performance (as affected by variables such as deck run, wind over deck, aerodynamic lift and thrust margin); carrier design; operational issues (such as sortie generation rate); and safety.

Further feasibility investigations were conducted in 2000-01 using generic aircraft and ship models. Dstl also ran a two-day safety workshop in late 2001. This showed that there were no "showstoppers, and no SRVL-specific safety critical systems were identified", said Rosa. "Also, the ability to ditch weapons and carry out a vertical landing instead of an SRVL in the event of a failure was seen as a powerful safety mitigation."

During 2002, more representative F-35B information became available which altered assumptions with respect to aircraft 'bring back' angle of attack (from 16 degrees to about 12 degrees, so reducing the lift co-efficient); wing area (revised downwards from 500 ft2 to 460 ft2, reducing lift available on approach at a given speed by 8 per cent); and jet effects in the SRVL speed range (which were significantly greater than those in the hover).

Aggregated, these revised assumptions significantly reduced predicted bring back performance. Even so, the improvement offered by an SRVL recovery was still substantial and MoD interest continued.

In the 2003-04 timeframe, Lockheed Martin became formally engaged in the investigation of SRVL recovery, with the JPO contracting with Team F-35 for a study into methods for Enhanced Vertical Landing Bring Back. Once again, safety and performance characteristics were considered broadly encouraging. "However," pointed out Rosa, "at this stage work on the adaptable CVF design was progressing rapidly.... Consequently the obvious next step was to consider the detailed impacts that SRVL might have on the CVF design."

Back to reality
Accordingly, the CVF IPT (now subsumed into the wider ACA) in 2005 put in place a package of work to investigate SRVL impact on the carrier design.

This comprised three workstrands: analysis to establish the optimal SRVL recovery deck; sortie generation rate modelling; and MITL simulator trials to establish the most appropriate recovery profile, analyse VLAs and measure landing scatter.

Two separate simulation trials were conducted at BAE Systems' Warton facility using a representative CVF ship model and a F-35 representative air and ground model. The results indicated that, at night or in higher sea states (above Sea State 3), an SRVL-specific approach aid was desirable, and Ship Referenced Velocity Vector (SRVV) symbology in the pilot's helmet-mounted display was an enhancing feature.

One significant outcome of the JCA Review Note promulgated by the IAB in July 2006 was the decision to add an SRVL capability into the overall SDD programme. Significant work has been performed since then, including land-based flight trials and extensive simulator-based development and evaluation.

As part of this work, QinetiQ was in 2007 contracted to use its Harrier T.4 Vectored-thrust Advanced Aircraft Control (VAAC) testbed to perform representative land-based flight trials and a ship-based SRVL demonstration. The latter saw the VAAC aircraft perform a series of SRVL recoveries aboard the French carrier Charles de Gaulle in June 2007.

According to the MoD, these flight trials "demonstrated that SRVL was a safe recovery method to the ship at Sea State 6 in day, visual conditions", although it added that Charles de Gaulle is a "particularly stable ship" and there is "no ship motion data to enable comparison to how CVF will react in the same sea conditions".

Other forthcoming work will include further investigations on an SRVL clearance aboard CVF, optimisation of the approach profile, reaching an agreement on the optimal post-touchdown technique, and mitigation for failure cases such as a burst tyre on touchdown.

Work is also to continue to mature the SRVL-optimised VLA arrangements, look at the possible 'tuning' of the F-35 flight control laws, and further study the effect of SRVL on the CVF sortie generation rate, Rosa said, while acknowledging that the "exact scope of capability is only likely to be confirmed after First of Class Flying Trials" aboard CVF.

RAY OF LIGHT: COMPLEMENTARY VLA SOLUTIONS FOR ALTERNATIVE RECOVERY MODES
The purpose of a landing aid system is to assist the pilot during approach and recovery to the ship by day or night. As baselined for STOVL operations (with emphasis on a vertical recovery manoeuvre), the CVF design includes a Glide-slope and Long-range Line-up Indicator System (GLIS), a HIHAT and light emitting diode flight deck lighting. AGI has been contracted by the ACA to supply these as part of a GBP7.5 million (USD11.5 million) contract for the supply of visual landing aids (VLAs) for both fixed- and rotary-wing aircraft.

The GLIS system, based on two night-vision goggle-compliant stabilised Glide Path Indicator (GPI) units, is the primary source of information available to the pilot for establishing and maintaining the correct glide slope during the approach. These GPI units are positioned at either end of the ship, in the port catwalk level with the flight deck. High intensity drop-line lights, mounted on the stern of the ship, provide line-up cues.

Each GPI is essentially a high intensity sectored light projector. The glide slope of the aircraft, relative to the GLIS, determines which coloured light sector is visible to the pilot. If the pilot is flying down the optimum glide slope (nominally three degrees) a steady green light is visible. If the approach is too high a flashing green light is visible. Alternatively, if the approach is too low a red light will be visible. A steady red light indicates a slightly low approach and a flashing red light indicates a very low approach.

HIHAT consists of 11 lights fitted in a vertical stack with two standard deck lights mounted horizontally, one either side of the stack, at the optimum aircraft hover height (which aligns to the fourth vertical light, thus resulting in three lights above this position and seven below).

Light output from each of the vertical lights is designed such that it can only be seen when level with or above the centre line of the light; it cannot be seen from below this level. Thus if the unit is viewed at the optimum hover height then a T shape, consisting of the vertical stack of lights horizontal deck lights, will be seen. Moving above this position will result in more vertical lights being observed and a decrease in height will have the opposite effect, though the horizontal reference will still be visible. The spacing of the lights will also give a clear indication as to the rate of ascent or descent as more lights are illuminated or extinguished, and the rate at which this occurs.

Whilst the HIHAT is primarily intended to be used once the aircraft is over the deck and in the hover phase of the flight, it is anticipated that pilots will acquire the HIHAT at anything up to 0.5 n miles from the ship. The system is intended to complement the information obtained from GLIS and between them will provide a complete visual approach aid for a vertical recovery.

With SRVL now likely to be used as a recovery technique on board CVF, there is an additional requirement to augment the baseline VLA suite with a landing aid appropriate to the SRVL approach manoeuvre. To this end QinetiQ has undertaken research into a new VLA concept, known as the Bedford Array, which takes inputs from inertial references to stabilise against deck motions (pitch and heave).

A trial of the concept was undertaken aboard the aircraft carrier HMS Illustrious in November 2008, with QinetiQ using its Harrier T.4 VAAC testbed to fly approaches to a demonstration Bedford Array mounted on the ship. For the purposes of the trial, the lighting array was installed in the port catwalk adjacent to Illustrious's flight deck. The VAAC Harrier did not actually perform SRVL recoveries to the ship owing to the limited dimensions of the flight deck, but flew representative SRVL approach profiles to the catwalk array (down to a safety height of about 40 ft above deck) to evaluate its ability to accurately indicate an SRVL glide scope aimpoint to the SRVV.

A second lighting array was rigged on the carrier flight deck itself. This was used for a parallel evaluation of the visual acuity of the lighting system on deck.


A NEW ANGLE: OPTIMISING THE SKI-JUMP PROFILE FOR CVF
The origin of the ski-jump ramp now widely fitted to aircraft carriers undertaking fixed-wing STOVL air operations at sea is widely credited to Lieutenant Commander Doug Taylor RN. His thesis, written while studying for a PhD at the University of Southampton in the early 1970s, identified the substantial gains in payload radius achieved if an aircraft performing a short takeoff - such as the Harrier with thrust vectoring - was launched upwards on a semi-ballistic trajectory.

The ski-jump ramp works by imparting an upward vertical velocity and ballistic profile to the aircraft, providing additional time to accelerate to flying speed whilst ensuring it is on a safe trajectory. This additional time is manifested either in a reduced take-off length for a given weight, or increased launch weight (fuel and/or ordnance) for a fixed take-off distance.

This additional performance does not come for free, however, with a significant increase in landing gear loads above those of a standard take off, which are very low compared to a landing. The increase represents the energy transferred to the aircraft as it translates up the ramp; and if the angle and curvature of the ramp are increased to obtain greater performance benefit, so are the loads.

An essential first step for optimising the ski-ramp profile for CVF was to define key performance and load cases (in terms of aircraft configurations and environmental condition thresholds). Other ground rules such as take-off distances, maximum ramp length and height constraints, wind over deck speeds and ship motion factors were also generated prior to the main analysis which was based on legacy experience with Harrier analysis, Team F-35 'best practice', sensitivity studies of performance and loads to identify sensible values and ranges.

Based on predicted F-35B performance and landing gear loads data, the CVF ski-jump was defined as a 12.5 degrees angled ramp, with the profile achieved by combining a nominal profile based on a quartic fit to an optimum cubic transition plus circular arc, a rounded step lead in and an elliptic let down. Analyses have also confirmed that fatigue impact as a result of cyclical loading was significantly less than that for the legacy Invincible-class ramp; and that minimum weapons physical clearance limits were met even in worst cases (combinations of flat tyres and compressed struts).


OPTIMISING HEALTH, SAFETY AND PERFORMANCE IN THE FLIGHT DECK ENVIRONMENT
Extensive modelling and simulation work has been performed to characterise the CVF flight deck environment, bearing in mind that interleaved launch and recovery and simultaneous turnaround (taxiing, parking, servicing, fuelling and arming) activities must co-exist within a constrained four-acre estate. The need to ensure a safe working environment for personnel on deck has come in for particular scrutiny given the jet wash and near-field acoustic impacts associated with the F-35B.

Under contract to the ACA, Frazer Nash Consultancy (FNC) used transient computational fluid dynamic (CFD) modelling to map the jet blast impact of a JCA on launch, and evaluate measures to improve flight deck operational performance with minimal impact to the ship design. This involved evaluating the protection offered by the legacy flat plate Mk 7 Jet Blast Deflector (JBD) and a number of variations to this layout.

CFD modelling was used to simulate the engine power and acceleration of the JCA along the launch runway, with the exclusion zones generated by the hot high-velocity exhausts visualised, and peak values at key personnel locations were monitored throughout the launch.

A CVF model suitable for transient CFD analysis was developed from an existing air wake model. The F-35B was not modelled explicitly; instead the core nozzle and lift fan were represented as surfaces of the correct exit area with a pressure and temperature boundary condition applied. This was calculated from an extensive dataset supplied by Team F-35 through the JCA integration contract and checked by comparing the exhaust mass flow and thrust predicted by the CFD.

Results showed that the large efflux mass flow associated with the F-35B lift fan hits the flight deck at an angle and spreads out sideways and backwards, pushed behind the aircraft and then curling up into vortices either side of the strong central jet from the core nozzle. CFD analysis showed that the JBD provided some protection to the aft flight deck at the start of the launch but was less effective as the aircraft moved down the launch runway. Protection is particularly poor on the port aft quarter of the deck.

FNC subsequently investigated six alternative JBD layouts in an effort to identify a solution offering better protection to personnel on the aft deck. Its optimised configuration afforded a better level of protection for personnel on the port aft flight deck, although an exclusion zone would still be required on the flight deck where the jet wash is deflected outboard and where it propagates around the starboard side of the JBD. Nevertheless, the size of the exclusion zone would not limit flight deck operations.

In the final analysis, the decision has been taken to delete the JBD from the STOVL CVF design. Cdr Lison explains: "We determined from the CFD modelling that the legacy JBD did not offer adequate protection. Alternative designs were considered which offered some benefit, but two considerations persuaded us to delete the requirement.

"First, the nozzle scheduling of the F-35B on take-off has yet to be fully established, and there was a risk that the jet blast would simply 'bounce' over the JBD. Second, the JBD was in a single fixed position on the flight deck, so there was no flexibility with regard to the length of the take-off run."

Work has also been carried out to map the acoustic footprint on deck: noise is a major health and safety consideration, given that deck personnel in close proximity to the JCA on take-off will be subject to increased sound levels above the legacy Harrier. Acoustic shelters are incorporated in the CVF design, while deck personnel in the near field will be equipped with advanced hearing protection devices.

"It's an issue we take very seriously because of the potential for permanent damage to hearing," says Cdr Lison, adding: "We've looked across the Atlantic to the F-35 programme and beyond to a SBIR [Small Business Innovation Research] effort being sponsored by the Naval Air Systems Command. Under these efforts, ATI/Aegisound is developing deep ear insert active noise reduction sets to equip deck crews on US carriers in the near field. Our current intention is to buy into this as appropriate for UK requirements."

Another area of continuing research is flight deck coatings. "We have already conducted trials of some candidate coatings using a sub-scale jet engine in BAE Systems' hot gas lab at Warton," says Cdr Lison. "We are also liaising with the US Office of Naval Research to gain maximum value from combined US-UK efforts."

He adds: "Existing formulations will not withstand the intense heat of the F-35B jet blast, so the ACA, working with paint consultants Safinah, has developed a high level specification for a coating that addresses requirements for corrosion protection, heat and blast resistance, co-efficient of friction, ease of applicability, impact tolerance, and cost at application and through life.

"This specification will be promulgated to paint/coatings suppliers to see what they can deliver. We believe there is a product out there that meets our needs, but not necessarily one that is currently marketed as flight deck paint."
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Unread post22 Mar 2010, 15:33

The JBD thing is going to be a giant hinderance. Not being able to park aircraft behind is going to have a big effect on sortie rates when operating on Nimitz class ships they're going to have no option but a dedicated axial flight deck configuration.
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Unread post22 Mar 2010, 19:06

No JBD is for CVF. No information on Nimitz class operatons.
RAN FAA A4G: http://tinyurl.com/ctfwb3t http://tinyurl.com/ccmlenr http://www.youtube.com/user/bengello/videos
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Unread post27 Mar 2010, 04:35

F-35 Not Too Hot For Carriers (I hope it is not what it means in Ozian) By Colin Clark Friday, March 26th, 2010

http://www.dodbuzz.com/2010/03/26/jsf-n ... nt64258173

"The STOVL version of the Joint Strike Fighter is not too hot and is not too loud, Marine Commandant Gen. James Conway told DoD Buzz during an editorial board session.

The most troubling operational challenge that appeared to face the F-35B, next to weight, was reports that it would not be suitable for a carrier or other ship because its exhaust would melt the flight deck. Not so, Conway told reporters from Military?.com. The plane, at 1,500 degrees, is just 18 degrees hotter than a Harrier, he said Thursday.

He also debunked persistent reports that the F-35 will blow the ears off of people living near their flight paths, Conway said that noise levels for the plane are “well in range of legacy aircraft” like the F-22 and the F/A-18 E/F. Bottom line, the F-35 ain’t a whisper jet, but communities familiar with existing aircraft shouldn’t have much to worry about.

On the negative side, Conway noted that “we will lose 28 aircraft over the FYDP” but said he thought the “news for us on F-35 is relatively positive” given the recent test successes at Patuxent River...."

[In "Ozian" 'Not Too Hot' means "Not Very Good"] :P
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Unread post04 Apr 2010, 07:58

Elsewhere on this forum is info about the lecture: (seems to have disappeared?)

F-35 - Inventing the Joint Strike Fighter Dr. Paul Bevilaqua - Lockheed Martin Skunk Works - 12 Oct 2009

http://www.nps.edu/Academics/Institutes ... ighter.pdf (4.5Mb)
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3 videos of lecture here - I guess the PDF above is useful as notes for lecture?:

http://www.flightglobal.com/blogs/the-d ... -by-s.html

VIDEO: History of the F-35 by Skunk Works inventor (3 parts) By Stephen Trimble on March 22, 2010

"The DEW Line is pleased to offer a three-part video showing a fascinating (albeit poorly-lit), 1hr lecture on the F-35 Joint Strike Fighter, presented last week by Skunk Works engineer Paul Bevilaqua at Johns Hopkins University's applied physics laboratory in Laurel, Maryland. Bevilaqua is credited with the invention of Lockheed Martin's shaft-driven lift-fan, the core technology allowing the short-takeoff-vertical-landing (STOVL) F-35B. The first part of the lecture is below, and click on the jump to view the other two parts."

Lecture part 1 .FLV video 78Mb
Lecture part 2 .FLV video 85Mb
Lecture part 3 .FLV video 43Mb
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total time 65min / total size 206Mb
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Here is the 'cool video' clip of the STOVL heating issue being simulated (thanks be to the DEWline)....
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JSFlectureConcreteSimWMM.wmv [ 9.73 MiB | Viewed 12899 times ]

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Unread post04 Apr 2010, 08:10

Here is a direct link to the video if it cannot be seen above (I cannot see it using Win7 & Internet Explorer 8 ):

http://s98.photobucket.com/albums/l261/ ... SimWMM.flv
OR
samesame video:
http://alturl.com/pg7c
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Here is the 10Mb .WMV video (same as above):

http://www.filefront.com/16021099/JSFle ... SimWMM.wmv
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