F-35B/C and the Ski-Jump?

[spazsinbad]

Ski Jump at INS Hansa (NAS Goa) is on the West Coast of India whilst the jump direction is from East to West to be more or less over the sea just after exiting the ramp. I'll look to see if Google Earth has an up to date photo: now JUNE 2014. CLICK de PICs for the ZOOM view.

[spazsinbad]

Similar to the USN LSO setup (LSODS) Landing Signal Officer Display System (which has many components including a display which looks like this set up at INS Hansa SBTF at the OLS/Arrest Gear Test site).

TV Landing System SBTF
“To assist Landing Signal Officer (LSO) regarding position of aircraft approaching to land on Deck. TV Landing System provides aircraft visible distance of 6 Km, monitoring aircraft from 5 Km, auto tracking from 4.5 Km and measuring range and deviation from Glide path from 3 Km away from touchdown point. TV Landing System has two cameras mounted on landing runway axis and two cameras are installed on both sides from landing runway axis at distance of 16 m from axis for determination of distance to touch down.”

[spazsinbad]

Did not notice this factoid about the SBTF Ski Jump Location earlier. Nice to have a long drop for testing.... Graphic from same source (click on it to ZOOM in).

"...“The Indian SBTF, a replica of ‘Nitka’, will be equipped with a 14 degree ski-jump located at the end of a taxi-track, on a 150 foot high cliff overlooking the sea.” http://www.vayuaerospace.in/images1/The_LCA-NAVY.pdf (7.8Mb)"

Airport type, Naval Air Station; Operator, Indian Navy; Location, Dabolim, Goa, India
INS Hansa; Elevation AMSL: 184 ft / 56 m http://en.wikipedia.org/wiki/INS_Hansa

[zerion]

F-35 starting ski-jump testing this week.

http://www.reuters.com/article/2015/02/ ... AK20150224

[spazsinbad]

Thanks 'zerion'. Probably SHALAL has misunderstood something here (from 'zerion' URL above):

Lockheed F-35 heads for the ski jump in next key round of tests
24 Feb 2015 Andrea Shalal (Editing by Matthew Lewis) [I BLAME MAFEW ]

"...Two UK pilots will test the ability of the new warplane to take off from upward-sloping ski-jump ramps used on aircraft carriers like those operated by Britain and Italy. The ramps launch the jets forward and upward, reducing the thrust needed. [same same frust STOVL MODE IV but reduces the required takeoff distance - a KPP requirement indeedy]

[AND in the SPACE of a day the price has been reduced from 1.5 Trill Doritos to 0.5 (in Oz) to now...] ..."After 14 years of development, early cost overruns and schedule delays, the $400 billion F-35 fighter jet program is becoming an operational reality for the U.S. military. Over 120 jets are flying at nine U.S. bases...." [I LIKE IT! ]

Source: http://www.reuters.com/article/2015/02/ ... AK20150224

[KamenRiderBlade]

One day, somebody might attempt to combine the Catapult + Ski Jump and we will see the wonders of both technologies combined.

=D

[spazsinbad]

That idea has been canvassed before and does not make sense. The STOVL aircraft does the trick nicely UNLESS you are referring to a NAVALISED Aircraft such as LCA-NAVY or perhaps F-35C which may ski jump via catapult in A/B and arrest etc.? Still does not make sense because steam/EMALS can hurl heavy aircraft over a short distance similar to that taken up by the ski jump fitted. You need to be more clear about what is envisaged.

[KamenRiderBlade]

That idea has been canvassed before and does not make sense. The STOVL aircraft does the trick nicely UNLESS you are referring to a NAVALISED Aircraft such as LCA-NAVY or perhaps F-35C which may ski jump via catapult in A/B and arrest etc.? Still does not make sense because steam/EMALS can hurl heavy aircraft over a short distance similar to that taken up by the ski jump fitted. You need to be more clear about what is envisaged.

A EMALS based catapult that launches the aircraft across the launching deck, at the end of the deck is a Ski-Jump.

Catapult + Ski-jump

=D

[spazsinbad]

An EMALS can fling anything envisaged for the near term I'm told - I see no advantage for ski jump at all. One could argue that a small scale EMALS may do the work required in the shortest distance for a given known aircraft/weight. However IF the future needs are envisaged then perhaps a longer/larger EMALS is more sensible given that aircraft carriers have lives longer than aircraft carried - usually (that equation may change however).

Anyway the problem as told and now retold is the slow speed flying capabilities of any ski jumpin' aircraft. STOVL MODE IV fits that bill nicely. Carrier Enabled aircraft less so - usually that means they have a limited takeoff weight. NOW throw a heavily laden carrier based aircraft at a ski jump so as to achieve min safe flying control speed at the top of the jump. I have an almighty undercarriage collapse going up the jump in my mind's eye - but you may not.

However if you envisage an EMALS catapult embedded IN the ski jump then (with a lesser angle) perhaps this is more sensible? AFAIK [French Navy trial] adding a small upward part at the end of a conventional catapult has been tried (and not deemed useful) because perhaps that upward part was not very long as I recall. So back to you....

[KamenRiderBlade]

An EMALS can fling anything envisaged for the near term I'm told - I see no advantage for ski jump at all. One could argue that a small scale EMALS may do the work required in the shortest distance for a given known aircraft/weight. However IF the future needs are envisaged then perhaps a longer/larger EMALS is more sensible given that aircraft carriers have lives longer than aircraft carried - usually (that equation may change however).

Anyway the problem as told and now retold is the slow speed flying capabilities of any ski jumpin' aircraft. STOVL MODE IV fits that bill nicely. Carrier Enabled aircraft less so - usually that means they have a limited takeoff weight. NOW throw a heavily laden carrier based aircraft at a ski jump so as to achieve min safe flying control speed at the top of the jump. I have an almighty undercarriage collapse going up the jump in my mind's eye - but you may not.

However if you envisage an EMALS catapult embedded IN the ski jump then (with a lesser angle) perhaps this is more sensible? AFAIK [French Navy trial] adding a small upward part at the end of a conventional catapult has been tried (and not deemed useful) because perhaps that upward part was not very long as I recall. So back to you....

http://www.dtic.mil/dtic/tr/fulltext/u2/a237265.pdf

The reason I mention the "Ski Jump + Catapult" is that it was either you Spaz, or somebody else who linked an USAF study on a mobile land based Ski Ramp that can be stored somewhere and moved to anywhere on a runway as needed to shorten takeoff distances for most aircraft. In the event that the runways get cratered, you can move a Ski Ramp to a good section of a runway and allow aircraft to takeoff in a short distance.

My logic being that if it can help shorten the distance of combat aircraft taking off, it could help at least increase the payload that the aircraft can take off with from a carrier assuming the existing carrier doesn't change dimensions.

If there is too much engineering that needs to be done to make this work on top of the existing catapult, than save it as an idea down the line for any future carrier designs.

[madrat]

One day, somebody might attempt to combine the Catapult + Ski Jump and we will see the wonders of both technologies combined.

=D

Or using multiple decks so you can launch first down a slope then back up off the ramp. I like the idea of an external rail away from the deck that does the same thing, with the rail vertically reminiscent of an S-curve. Keep launch space excluded from recovery and unloading space.

[spazsinbad]

As I recall 'madrat' introduced some ideas about catdepultingwhilstskijumping onandoff multiple decks with a hair dryer at the other end (or both) to provide extra vertical lift over the ramp? I'll find that or those threads at some point if required.

Meanwhile back to KRB thoughts about land based aircraft using a portable ski jump from uncratered portions of conventional runways.... Without looking at the PDF again I would suggest that the ski jump angle is less than 12-14 degrees as seen on flat deck ski jumps today (UK & Ruskie/Indian respectively). Then there is another PDF about 'gravity assisted land based ski jumping which 'madrat' may refer to obliquely (when at first the aircraft goes down the dip then up [a large crater hollowed out]?

KRB:

"...My logic being that if it can help shorten the distance of combat aircraft taking off, it could help at least increase the payload that the aircraft can take off with from a carrier assuming the existing carrier doesn't change dimensions.

If there is too much engineering that needs to be done to make this work on top of the existing catapult, than save it as an idea down the line for any future carrier designs."

Again it would be nice if you were more specific. For some 60 or more years naval aircraft have been assisted off their respective flat decks by hydraulic (even earlier with some other weird gizmology) and now STEAM with Future EMALS catapults. The logic and utility of these catapults is well known and quantified and still around for conventional carriers because it is useful. The penalties of such usefulness are also well known when first the naval aircraft is catapulted and then recovered via arrestor gear.

If one reads the info about Tejas LCA-NAVY one has the gist that the undercarriage was initially over engineered, after following Russian design suggestions? Now another undercarriage has been designed that enables the same events (ski jumping and arrest) with much less weight - always a good thing. Whilst there is a comment in one of the PDFs that says to the effect 'things need to be engineered precisely so that there is no over/under engineering' for the LCA-NAVY, precisely so that max weight for take off is enabled via ski jump in distance allowed.

Once again I'm a little stuck about what is envisaged. An EMALS catapult will fling anything allowable up to the breaking point of said flungee. For an A-4 Skyhawk that max. horizontal G allowable was 9! OUCH! For naval aircraft today that is now probably about 7 G but I'm only guessing. VX-23 Test Pilots have mentioned going up to 6G during their Hornet catapult tests which is above what is required usually on USN catapults. So there are a few factors involved in engineering a catapult / arrest aircraft - let alone design a functioning arrestor hook (without wirebrushing the team).

P'raps an EMALS incorporated into a gentle ski jump may be OK but why? EMALS is able to at first gently accelerate the aircraft (whereas STEAM has the max G right at beginning) to intelligently increase acceleration to the required endspeed. IF a nugget T-45C pilot keeps his feet on the brakes during catapulting the EMALS will recognise a problem and increase acceleration to required endspeed - despite the smoking brakes and blown tyres. Yay EMALS!

So my suggestion is: go with EMALS on aircraft carriers and go with Ski Jumps on STOVL carriers. Even Indian NEXT carrier after the one being built now is said to be going to have EMALS (via recent tech agreements with US after PrezVisit) and EVEN the Ruskinators are saying similar - although their next carrier construction is TO BE FINISHED by 2025 hence - WOT!

India now puts aircraft carrier plan on fast track
23 Feb 2015 Rajat Pandit, TNN

"...But the carrier will definitely have CATOBAR (catapult assisted take-off but arrested recovery) configuration for launching fighters as well as heavier aircraft from its deck. Towards this end, India has already asked the US to share technology for EMALS (electromagnetic aircraft launch systems), developed by General Atomics, under the bilateral Defence Trade and Technology Initiative, as reported by TOI earlier...."

Source: http://timesofindia.indiatimes.com/indi ... 336472.cms

Russia May Finalize its Flagship Aircraft Carrier by 2025
15 Feb 2015 Russia

"The construction of a flagship air carrier for the Russian Navy may be finalized before 2025, a Russian Navy spokesman said....

...He added that the aircraft-related research work is now under way and that several projects related to the vessel's construction are already on the table.

Earlier, the Russian Navy's Deputy Commander on Armament Victor Bursuk said that the new aircraft carrier would be built after 2030...."

Source: http://sputniknews.com/russia/20150215/1018305548.html

[KamenRiderBlade]

Realistically, I wouldn't suggest making the change now in production ships.

Just investigate the concept for future designs.

[spazsinbad]

Realistically I do not see the benefit of what exactly? Please elaborate. Is the EMALS incorporated in the ski jump or as you have first suggested? Where is the benefit from the options already canvassed. I see the STOBAR players going conventional and even perhaps NUCKCLEAR for the benefits - including electric power generation for EMALS!

[KamenRiderBlade]

Realistically I do not see the benefit of what exactly? Please elaborate. Is the EMALS incorporated in the ski jump or as you have first suggested? Where is the benefit from the options already canvassed. I see the STOBAR players going conventional and even perhaps NUCKCLEAR for the benefits - including electric power generation for EMALS!

The EMALS could be incorporated into the ramp or stopped just before the start point of the ramp.

The design depends on the test data really.

But the benefits would be allowing even heavier loads than existing max gross weights to take off.

But if there is no aircraft that needs to go heavier, than the existing solutions would work.

I'm making assumptions that future aircraft will be pretty heavy or have options to load up in weapons + fuel to be even heavier than current limits.