Pentagon’s Operational Test and Evaluation Report 2012 PDF

Pentagon’s Operational Test and Evaluation Report 2012 PDF

http://timemilitary.files.wordpress.com ... report.pdf (0.5Mb)

ONE example page/table of issues for the F-35B with several pages of text for both B/C (A versions have their own pages of course). So best read the PDF eh. F-35B STOVL Door Issues plus this (amongst other reasons) may be why we don't see/hear much about SRVL these days: [Some of this same text will be added to the appropriate threads]

F-35B:
"...Planned wet runway testing, required to assess braking performance with a new brake control unit, has been delayed due to the inability to create the properly degraded friction conditions at the Patuxent River Naval Air Station (NAS), Maryland. The F-35B training aircraft at Eglin will be restricted to dry runway operations only until the wet runway testing is completed...."
____________________

F-35C:
"...The test team investigated alternative trailing edge flap settings to improve flying qualities during carrier landing approach. While pilot surveys showed handling qualities were improved with a 15-degree flap setting, flight test data to date have shown that 30 degrees of flaps are required to meet the KPP for maximum approach speed of 145 knots at required carrier landing weight...."
__________________________

Discoveries included:
-- The test team continued to work through technical problems with the helmet-mounted display system, which is deficient. The program was addressing five problems at the time of this report. Jitter, caused by aircraft vibrations and exacerbated by aircraft buffet, makes the displayed information projected to the pilot hard to read and unusable under certain flight conditions. Night vision acuity is not meeting specification requirements. Latency of the projected imagery from the DAS is currently down to 133 milliseconds, below the human factors derived maximum of 150 milliseconds, but still requires additional testing to verify adequacy. Boresight alignment between the helmet and the aircraft is not consistent between aircraft and requires calibration for each pilot. Finally, a recently discovered technical problem referred to as “green glow” has been experienced when light from the cockpit avionics displays leaks into the helmet-mounted display and degrades visual acuity through the helmet visor under low ambient light conditions. The test team is planning additional, dedicated ground and flight testing to address these technical problems...."
____________________________________________

FRECK!
• In 2011, the Air Force airworthiness authorities identified the pilot escape system installed in the early LRIP aircraft as a serious risk. Validation of expected performance of the F-35 escape system is supported by modeling the ejection seat as well as the effectiveness of the transparency removal system for the canopy during the ejection sequence.

-- For the ejection seat model, the program used data from sled testing under straight and level conditions to predict performance of the ejection seat under non-zero angle-of-bank (including inverted) conditions. Interactions between the pilot, the ejection seat, and the canopy during the ejection sequence, however, are not well understood, particularly during other than straight and level ejection conditions.

-- Testing of the transparency removal system under off-nominal conditions to better understand these interactions was scheduled for March 2012. The program expects this testing to take place in December 2012....

...lack of a water-activated parachute release system (qualification testing is delayed until 2013); incomplete testing of the escape/ejection system;..."
___________________________________________________

Air System-Ship Integration and Ship Suitability Testing
F-35B
• The Program Office continued planning efforts to support the next F-35B developmental testing deployment to USS Wasp in August 2013. Through the middle of November, the test team had accomplished 79 vertical landings in 2012 (358 total to date) and 212 short takeoffs (631 to date). Control law changes were made to the vehicle system software as a result of flying qualities observed during the first deployment to USS Wasp in 2011. Regression testing of the control law changes was accomplished in 2012.
• Discoveries affecting F-35B operations on L-class ships include:
-- Assessment of ship capabilities were inconclusive in determining whether there would be adequate storage requirements for lithium battery chargers and spares, gun pods, and the ejection seat carts as some of the support equipment and spares from legacy systems may no longer be required. Additional data are required to determine a path forward.
-- Propulsion system module containers do not meet all shipboard requirements. Due to the fragility of certain propulsion system components, there is significant risk to engines during transport to and from ships, using the current containers. The Program Office is coordinating a propulsion system fragility analysis which is expected to lead to a container redesign.
-- Concept of operations for managing and using the classified materials area remains to be resolved.

F-35C
• A redesign of the arresting hook system for the F-35C to correct the inability to consistently catch cables and compensate for greater than predicted loads took place in 2012. The redesign includes modified hook point shape to catch the wire, one-inch longer shank to improve point of entry, addition of damper for end-of-stroke loads, increased size of upswing damper and impact plate, addition of end?of?stroke snubber. In 2012, the following occurred:
-- Initial loads and sizing study completed showed higher than predicted loads, impacting the upper portion of the arresting hook system (referred to as the “Y frame,” where loads are translated from the hook point to the aircraft) and hold down damper (January 2012)
-- Risk reduction activities, including cable rollover dynamics testing at Patuxent River (March 2012), deck obstruction loads tests at Lakehurst (April 2012)
-- Flight tests with CF-3 using new hook point and new hold down damper design at Lakehurst (August 2012)
-- 72 of 72 successful roll-in tests with MK-7 and E-28 gear
-- 5 of 8 successful fly-in tests; 3 of 8 bolters (missed wire)
-- Preliminary design review of updated design completed (August 15, 2012)..."
_____________________________________________________________________

FROM: Hot Stuff: The F-35 Just Became 25% More Vulnerable By Mark Thompson Jan. 11, 2013

http://nation.time.com/2013/01/11/hot-s ... ulnerable/

Spaz,
Thanks for posting the STOVL issues table. All those door and actuator problems can be traced back to the difficulty, nay impossibility, of accurately predicting the design loads in an extremely complex turbulent flow environment. Note that the solutions to all those problems are found by adding load instrumentation, primarily calibrated strain gages, to the areas of interest and flight testing. Once the true load environment is known, redesign can begin with confidence.

I spent most of my work time flight testing with such instrumentation and fighting structural upper management, who always wanted to cut structural flight testing as a way to reduce program cost. "Why, son, with wind tunnels, CFD, flight simulators, and computers, we can predict all the loads we need!"

BFS

Interesting that it seems the the deletion of some fire suppression measures has made the ship "25% more vulnerable".... who could have foreseen that? Ahem....

"Recent tests show that removing nine pounds of fueldraulic fuses and two pounds coolant shutoff valves “results in a 25 percent increase in aircraft vulnerability.”

Notes the DOT&E report about those 32 ounces of valves:

The aircraft uses flammable PAO [Polyalphaolefin] in the avionics coolant system, which has a large footprint on the F-35. The threat in this ballistic test ruptured the PAO pressure line in the area just below the cockpit, causing a sustained PAO?based fire with a leak rate of 2.2 gallons per minute (gpm). The program assessed that a similar event in flight would likely cause an immediate incapacitation and loss of the pilot and aircraft. The test article, like the production design, lacks a PAO shutoff system to mitigate this vulnerability."

Read more: http://nation.time.com/2013/01/11/hot-s ... z2HltAl1XQ

25% of what? This is not new info -- this was known nearly 5 years ago when the decision was made. "Recent tests" (publicly reported last year) confirmed the older analysis. And the fueldraulic fuses they quacked so loudly about didn't work, so the DOT&E analysis was flawed on that account wasn't it?

The report is most conspicuous for what it doesn't say.

johnwill wrote:Spaz,
Thanks for posting the STOVL issues table. All those door and actuator problems can be traced back to the difficulty, nay impossibility, of accurately predicting the design loads in an extremely complex turbulent flow environment. Note that the solutions to all those problems are found by adding load instrumentation, primarily calibrated strain gages, to the areas of interest and flight testing. Once the true load environment is known, redesign can begin with confidence.

I spent most of my work time flight testing with such instrumentation and fighting structural upper management, who always wanted to cut structural flight testing as a way to reduce program cost. "Why, son, with wind tunnels, CFD, flight simulators, and computers, we can predict all the loads we need!"

BFS

Why is it that no matter what company it is, public / private.

Upper management never values good testing procedures?

F-35 Marine Model Stress Testing Halted Over Cracks
By Tony Capaccio - Jan 12, 2013 12:47 PM ET

"Durability testing on the most complicated version of Lockheed Martin Corp.’s (LMT) F-35 was halted last month after “multiple” cracks were discovered in the fighter jet, according to the Pentagon’s testing office.
The previously undisclosed halt in high-stress ground testing involves the F-35B, the Marine Corps' version that must withstand short takeoffs and landings on carriers and amphibious warfare vessels, according to an annual report on the F-35 that Defense Department testing chief Michael Gilmore sent to Congress yesterday. Flight testing wasn’t affected."

http://www.bloomberg.com/news/2013-01-1 ... racks.html

More cracks... that is a hassle but they will be sorted out.


A more interesting story in my opinion is that this latest report actually indicates the extent to which the F-35 is failing to meet its acceleration and sustained turn requirements.

In the case of the A and B versions the acceleration shortfall is moderate while the sustained turn shortfall is more significant. In the C the turn performance essentially hits the mark but they missed the acceleration requirement by a country mile, suggesting in the C's case that it will never offer performance as originally envisioned. (and required by the Navy)

The program announced an intention to change
performance specifications for the F-35A, reducing turn
performance from 5.3 to 4.6 sustained g’s and extending
the time for acceleration from 0.8 Mach to 1.2 Mach by
8 seconds. These changes were due to the results of air
vehicle performance and flying qualities evaluations.

page 5

The program announced an intention to change performance
specifications for the F-35B, reducing turn performance from
5.0 to 4.5 sustained g’s and extending the time for acceleration
from 0.8 Mach to 1.2 Mach by 16 seconds. These changes
were due to the results of air vehicle performance and flying
qualities evaluations.

Page 6

The program announced an intention to change performance
specifications for the F-35C, reducing turn performance
from 5.1 to 5.0 sustained g’s and increasing the time
for acceleration from 0.8 Mach to 1.2 Mach by at least
43 seconds. These changes were due to the results of air
vehicle performance and flying qualities evaluations.

hobo wrote:More cracks... that is a hassle but they will be sorted out.


A more interesting story in my opinion is that this latest report actually indicates the extent to which the F-35 is failing to meet its acceleration and sustained turn requirements.

In the case of the A and B versions the acceleration shortfall is moderate while the sustained turn shortfall is more significant. In the C the turn performance essentially hits the mark but they missed the acceleration requirement by a country mile, suggesting in the C's case that it will never offer performance as originally envisioned. (and required by the Navy)

Time for those Block IV (or is it V?) "propulsion improvements" to be moved up ahead of schedule methinks...

Yes, Henny Penny...the sky is falling, the sky is falling...

johnwill wrote:Spaz,
Thanks for posting the STOVL issues table. All those door and actuator problems can be traced back to the difficulty, nay impossibility, of accurately predicting the design loads in an extremely complex turbulent flow environment. Note that the solutions to all those problems are found by adding load instrumentation, primarily calibrated strain gages, to the areas of interest and flight testing. Once the true load environment is known, redesign can begin with confidence.

I spent most of my work time flight testing with such instrumentation and fighting structural upper management, who always wanted to cut structural flight testing as a way to reduce program cost. "Why, son, with wind tunnels, CFD, flight simulators, and computers, we can predict all the loads we need!"

This discovery is all a consequence of FLIGHT test, and they all have a production cut-in or 'replace by attrition' which means the redesigns are done. So what is your point?

Another concise overview (whilst keeping all the details in the 18 page PDF in mind)....

Pentagon report cites "lack of maturity" of Lockheed F-35 jet ANDREA SHALAL-ESA, Reuters, January 13, 2013

http://www.northumberlandtoday.com/2013 ... d-f-35-jet

"...More work was also needed on a system aimed at protecting the plane from fuel tank explosions caused by lightning, the report concluded, noting that flight operations were currently banned within 25 miles of known lightning conditions.

No immediate comment was available from the Pentagon’s F-35 program office."

ONLY the last two sentences excerpted here - go to URL for the rest.

kamenriderblade wrote:

johnwill wrote:Spaz,
Thanks for posting the STOVL issues table. All those door and actuator problems can be traced back to the difficulty, nay impossibility, of accurately predicting the design loads in an extremely complex turbulent flow environment. Note that the solutions to all those problems are found by adding load instrumentation, primarily calibrated strain gages, to the areas of interest and flight testing. Once the true load environment is known, redesign can begin with confidence.

I spent most of my work time flight testing with such instrumentation and fighting structural upper management, who always wanted to cut structural flight testing as a way to reduce program cost. "Why, son, with wind tunnels, CFD, flight simulators, and computers, we can predict all the loads we need!"

BFS

Why is it that no matter what company it is, public / private.

Upper management never values good testing procedures?

Profit, Kam. Testing happens at the far right end of the schedule. To get back on schedule, the OBVIOUS solution is to squeeze testing.

Same thing happens in software test, johnwill. Management never wants to spend money on full regression testing.
"Adding a weapon will NOT affect existing weapons" was the quote I heard just before we discovered that our newest tape mod resulted in a NO launch of A-A missile 33% of the time and that was F-16 code. The F-35 is a code monster by comparison.
fisk

maus92 wrote:F-35 Marine Model Stress Testing Halted Over Cracks
By Tony Capaccio - Jan 12, 2013 12:47 PM ET

"Durability testing on the most complicated version of Lockheed Martin Corp.’s (LMT) F-35 was halted last month after “multiple” cracks were discovered in the fighter jet, according to the Pentagon’s testing office.
The previously undisclosed halt in high-stress ground testing involves the F-35B, the Marine Corps' version that must withstand short takeoffs and landings on carriers and amphibious warfare vessels, according to an annual report on the F-35 that Defense Department testing chief Michael Gilmore sent to Congress yesterday. Flight testing wasn’t affected."

http://www.bloomberg.com/news/2013-01-1 ... racks.html

Boo-hoo

...and the first 100 or so Super Hornets are sitting against a fence somewhere because they are life limited at ~1500 hours. (Although IIRC some were converted to 'G's and in the process had the structural mods incorporated).

F-35 durability testing (each variant) stops every 1000 hr interval for inspections of the test article. The inspection and resolution (RCCA) period for the BH will end in the next week or so. Better to find it now, which is why they do the testing.

A quote from a 1998 GAO report on Super Hornet -- "The primary purpose of the development test program is to identify system deficiencies so they can be corrected...". Imagine that...

The area that I think should generate concern is amount of capabilities in the software that is being deferred to later releases.