India and the F-35?

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steve2267

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Unread post13 Feb 2020, 20:45

spazsinbad wrote:The ramp at Pax River angle can be adjusted IIRC. However these days data can be massaged by computer if angle is diff.


I imagine the aero / performance data can be massaged. I guess I was thinking more in terms of mechanical / dynamic effects on the gear getting smashed down by the sudden change in angle.

However, as I type this... it occurs to me the "sudden" change in vehicle path or motion may be very gradual compared to the highly dynamic effect of a carrier landing (controlled crash).
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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Unread post13 Feb 2020, 21:12

Yes the initial Harrier Ski Jump trials revealed the need to strengthen the landing gear bits IIRC for ski jumping launch? Yes the vertical landing stresses the gear but the ramp needed to be curved sideways to reduce stress on the gear IIRC?
Royal Navy Aircraft Carrier Ski Jumps – a History
12 Aug 2019 ORIGINAL from SAVEtheRoyalNavy https://www.savetheroyalnavy.org/royal- ... a-history/

"...Lessons learned
The ski jump is a relatively cheap and simple addition to the carriers, being a straightforward steel construction with no moving parts. However it was discovered, once in service that apparently small differences in the build quality of the ramps of the three ships affected the life of the Sea Harrier undercarriage. The original design work assumed an absolutely smooth ramp but small ruts or imperfections in the surface were enough to cause cracking on some aircraft landing gear. This issue was expensively resolved and the lesson led to higher design tolerances being specified for the QEC ramps. Additionally, the F-35 has a wide tricycle gear which is more affected by small bumps, demanding more careful ramp design than for the Harrier’s tandem main gear. The centre section of the QEC deck is slightly cambered to help water runoff, further complicating the interface with the ramp...."

Source: https://www.faaaa.asn.au/a-short-history-of-ski-ramps/

Some good references for ski jumps: https://en.wikipedia.org/wiki/Ski-jump_(aviation)
AIRCRAFT OPERATIONS FROM RUNWAYS WITH INCLINED RAMPS (SKI JUMP)
May 1991 Elijah W. Turner

"ABSTRACT
The use of inclined ramps to launch aircraft from short runways is proposed as a possible solution to the runway denial problem in Europe. Past efforts to launch aircraft in this manner, including a very successful program conducted by the US Navy to launch the T-2C, F-14, and F-18 aircraft, are reviewed.

An analytical study was conducted for the launch of the F-16, F-15, A-10, A-7D and F-4E from inclined ramps. The takeoff ground roll, stabilizer trim setting, landing gear loads and flight trajectory are reported. The F-15 was selected as a candidate aircraft for a USAF flight test program to be patterned after the Navy program and additional studies were performed. Perturbations in center of gravity, thrust, and ramp exit angle were investigated.

A ramp contour was designed for launch of the F-15, F-16, A-7D and A-10 which minimized the length and height of the ramp while maintaining the landing gear loads below 90 percent of their design limit.

1.2 Ski-Jump Launch...
...This [USN] program generated an analytical effort in 1979 followed by a flight test program to launch the T2C, F-14, and F-18 aircraft from inclined ramps. A metal ramp was constructed that could be modified to give ramp exit angles of 3, 6, and 9 degrees. The ramp was 112.1 feet long and 8.58 feet high at the exit when configured for the 9 degree exit angle, measured from the horizontal. A total of 112 launches of the T-2C, 28 of the F-14, and 91 of the F/A-18 were made. The minimum ground roll for the F/A-18 was 385 feet at a gross weight of 32,800 lbs. This ramp effectively reduced the takeoff roll of the F-18 by more than 50 percent...."

Source: http://www.dtic.mil/dtic/tr/fulltext/u2/a237265.pdf (0.9Mb)
Last edited by spazsinbad on 13 Feb 2020, 23:15, edited 2 times in total.
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Unread post13 Feb 2020, 21:44

Google can't tell the diff between old & new INS VIKRANT which is annoying so:

https://the-drive-2.imgix.net/https%3A% ... c1fee13bae
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https___s3_amazonaws_com_the-drive-staging_message-editor%252F1503950272717-ins_vikrant_being_undocked_at_the_cochin_shipyard_limited_in_2015.jpg
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