F135 reliability

All about the Pratt & Whitney F135 and the (cancelled) General Electric/Rolls-Royce F136
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krorvik

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Unread post04 Apr 2016, 18:20

snypa777 wrote:Worth remembering that a 3 dB increase equates to almost 50% louder in audible noise for example.


Not really. It's a slippery slope when it comes to perception. If we're talking about 3dB increase in acoustic energt, it's barely perceptible. It is however a doubling of energy.

For a perceptible change, you need to add around 5dB of energy. To create a perceived doubling of sound, you actually need around 10dB. But perception is a strange beast.

You can also use the dbA-scale, which takes into account our sensitivity for frequency.

Now, a jet engine.... makes a spectrum of it's own. I'll defer that discussion to others....
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Unread post04 Apr 2016, 21:07

Thanks for all the input and to reinforce 'smsgtmac' post here is latest noise report summary PDF graphics: (PDF attached)

F-35 Noise Measurement Executive Summary 2014
SOURCE: http://www.jsf.mil/news/docs/20141031_F ... ummary.pdf (314Kb)
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20141031_F-35_Noise_Executive_Summary.pdf
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F-35 Noise Measurement Executive Summary 2014 GROUND.gif
F-35 Noise Measurement Executive Summary TOflyover.gif
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Unread post05 Apr 2016, 01:05

smsgtmac wrote:
snypa777 wrote:Cheers Spaz, was AA-1 the B model? That is where the complaints are centered but the other models are considered noisier than F-16s or F-18s in some quarters. Worth remembering that a 3 dB increase equates to almost 50% louder in audible noise for example.
2016 sucks, because everyone is risk averse and health and safety rules, I would LOVE some fighter jet noise near my house!
http://breakingdefense.com/2015/05/nois ... h-testing/

AA-1 was essentially an A prototype. Latest dB numbers I'm aware of were 2014. See the bottom of this post.
http://elementsofpower.blogspot.com/201 ... o.html?m=1

F-35A AA-1 apparently in better climes - now destroyed in live fire testing - years ago.
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Unread post10 Apr 2016, 08:00

For the slothfultone (no not 'maus92') OP text we now have the context. I'll highlight the 'engynbits' from SAR Dec 2015.
Selected Acquisition Report (SAR)
Dec 2015 Defense Acquisition Management Information Retrieval (DAMIR)

"...Executive Summary
The F-35 remains the DoD’s largest cooperative acquisition program, with eight International Partners participating with the U.S. under Memorandums of Understanding for System Development and Demonstration (SDD) and Production, Sustainment and Follow-on Development. Additionally, the program currently has three FMS customers. The F-35 program is executing well across the entire spectrum of acquisition, to include development and design, flight test, production, fielding and base stand-up, sustainment of fielded aircraft, and building a global sustainment enterprise.

The program is transitioning from slow and steady progress to a rapidly growing and accelerating Program. However, the Program is not without risks and challenges. The completion of Mission Systems Software development and Autonomic Logistics Information System (ALIS) development are the most prominent, current technical risks. The ability to standup four separate Reprogramming Labs, complete all weapons envelope testing for Block 3F, and start Operational Test (OT) on time, constitute the main schedule risks. Program leadership remains confident that it will deliver the full F-35 capability as promised.

Successes and challenges in 2015: The F-35 Program closed out 2015 by executing the plan for test flights, total test points and baseline test points. The test teams at Edwards Air Force Base (AFB) and Naval Air Station, Patuxent River, MD completed 1374 actual flights (plan: 1286), 9582 total test points (plan: 9427) and 7798 baseline test points (plan: 7786).
The Program also met the production goal for the year by accepting its 45th aircraft delivery. This represented a 25 percent increase from last year’s goal that was also met: the most aircraft delivered in one year in program history. These deliveries included the first international delivery from the Italian Final Assembly and Check Out (FACO), and bring the overall operational delivery total to 157 (146 U.S. aircraft as reflected in the Deliveries and Expenditure Section of the SAR, and 11 International Partner Aircraft) as of February 3, 2016. Along with Italy, Norway took its first delivery in 2015. Five partner nations: Australia, Italy, the Netherlands, Norway and the United Kingdom, along with the Air Force, Marine Corps and Navy, now fly the F-35. Israel and Japan will take their first deliveries in 2016.

Block 3i software was released for flight test in May 2015, to support the U.S. Air Force IOC declaration later in 2016. Coding for the final development software block 3F, was completed in June 2015 and the software has been released for flight testing. Additional updates are planned throughout the year with 3F tracking for completion by the end of the SDD in the fall of 2017, to support U.S. Navy IOC in 2018 and the start of Initial Operational Test and Evaluation (IOT&E). Throughout testing, interim software test builds are provided to both the developmental test and operational test teams, allowing them to experience the software as early as possible and provide feedback. As of December 31, 2015, the program completed 80 percent of SDD test points and is on track for completion in the fourth quarter of 2017.

At the completion of the F-35 SDD program, the objective is to deliver full Block 3F capabilities (Mission Systems, Weapons & Flight Envelope) for the Services and International customers. The F-35 program will continue to coordinate closely with the JSF Operational Test Team and Director, Operational Test and Evaluation, on key test planning and priorities to successfully meet significant SDD program milestones and objectives.

Currently, mission systems software and the ALIS system, are the program’s top technical risks. Disciplined systems engineering processes, addressing the complexity of writing, testing, and integrating mission systems and ALIS software, have improved the delivery of capability, although challenges remain....

...Earlier this year, the program reached agreement with Pratt & Whitney on the next two lots of F135 propulsion systems. The LRIP Lots 9 and 10 will continue the price improvements realized on previous lots and the F135 engine is meeting War on Cost commitments. For calendar year 2015, F135 production deliveries met contract requirements. However, recurring manufacturing quality issues continue to hamper consistent engine deliveries. Recent quality escapes on turbine blades and electronic control systems resulted in maintenance activity to remove suspect hardware from the operational fleet. Pratt & Whitney has taken action to improve quality surveillance within their manufacturing processes and program office manufacturing quality experts have engaged to ensure quality improvements are in place to meet production ramp requirements...."

Source: download/file.php?id=22832 (PDF 0.65Mb)
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Unread post10 Apr 2016, 15:45

also from the SAR

The F-35 family of aircraft variants will replace the following current aircraft: F-16C/D, A-10, F/A-18C/D, and AV-8B. The
F-35 O&S estimate is based on legacy fleet history only when F-35 specific data is not available.
Comparing the costs of the 5th Generation F-35 to legacy aircraft is challenging. The cost table above compares an
adjusted F-16C/D Cost per Flying Hour (CPFH) to a forecast of the CPFH for the F-35A variant. The F-35A CPFH figure
is based on the Conventional Takeoff and Landing (CTOL) variant only. The F-35A CTOL variant will make up the
majority of the DoD F-35 aircraft procurement, accounting for 1,763 of 2,443 total aircraft currently planned for U.S.
forces.

The F-16C/D CPFH figures were developed in a joint effort between CAPE and the Air Force Cost Analysis Agency. The figures have been normalized for comparison to the F-35A CPFH forecast. The starting point for the F-16C/D CPFH is
an average of actual cost incurred for this fleet during FY 2008 through FY 2010. In order to enable the direct comparison
of the CPFH figures, the actual F-16C/D CPFH is adjusted to reflect the cost of fuel, the number of flight hours forecast
for the F-35A, and FY 2013 inflation indices. The F-16C/D figures include costs that F-16 shares with other Air Force
platforms: Systems Engineering/Program Management (SEPM), maintenance training costs, certain software
development efforts, and information systems. Costs for mission planning are included in the F-35A CPFH figure, but
equivalent costs for the F-16C/D are not available, and no adjustment was made for this element of cost. Finally, the F-
16C/D figures assume full funding of requirements consistent with the F-35A CPFH figures.
Annual O&S Costs BY2012 $K
Cost Element
F-35 Aircraft
Average Annual Cost Per Flying
Hour
F-16C/D (Antecedent)
Cost Per Flying Hour ($)

(f-35 cost first then f-16 but best seen on page 91 of SAR)
Unit-Level Manpower 8.470 10.042
Unit Operations 4.923 5.632
Maintenance 11.126 5.501
Sustaining Support 3.179 2.075
Continuing System Improvements 2.108 2.291
Indirect Support 0.000 0.000
Other 0.000 0.000
Total f-35a 29.806 f-16c/d 25.541

The F-35A CTOL unitized cost figure shown in the table above decreased slightly relative to the comparable 2014 SAR
figure. There are three considerations that result in a slight decrease for the F-35A unitized cost shown above: 1) a
decrease in the assumed cost per gallon of JP-8 fuel; 2) a decrease in the fuel burn rate for the F-35A variant; and 3) a
revised cost estimating relationship for hardware modifications.
Given the significant increase in military capabilities provided, it is reasonable to expect F-35A to cost more to operate
and sustain than 4th generation legacy aircraft.
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Unread post10 Apr 2016, 16:27

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Unread post04 May 2016, 10:36

krorvik wrote:
snypa777 wrote:Worth remembering that a 3 dB increase equates to almost 50% louder in audible noise for example.


Not really. It's a slippery slope when it comes to perception. If we're talking about 3dB increase in acoustic energt, it's barely perceptible. It is however a doubling of energy.

For a perceptible change, you need to add around 5dB of energy. To create a perceived doubling of sound, you actually need around 10dB. But perception is a strange beast.

You can also use the dbA-scale, which takes into account our sensitivity for frequency.

Now, a jet engine.... makes a spectrum of it's own. I'll defer that discussion to others....


I think that "perception" is going to come from residents close to F-35 bases, I do not know whether its normal to test with the introduction of a new type but its happening in quite a few locations in both the US and in Europe as well as on board ships operating them.

I have been involved in noise testing in the past and what can increase audible noise, from my involvement I am going to stand by what I have said about small dB increases creating significant audible noise increases.
We had to redesign a noise enclosure because some VERY small apertures allowed noise to escape and increase audible noise in a remarkable and significant way, it doesn't take much at all and the data backed this up but of course the "type" or combination of noise will have a huge impact.
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Unread post04 May 2016, 13:02

That's the slippery part - jet noise is hard to lump into boxes like "A-weighting" - and made more difficult by landscape, buildings and other surroundings. Comparisons mandate otherwise identical parameters.

The rules of thumb mentioned apply though.
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Unread post04 May 2016, 22:21

There's a certain psychological aspect to it, as well. Not all noise is the same. A 100dB jazz concert and a 100dB hair metal concert will illicit different responses from the same group of people.
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Unread post04 May 2016, 22:32

spazsinbad wrote:There is at least one thread specifically about ENGINE NOISE: How loud is the F-35? in ENGINE subsection:
viewtopic.php?f=56&t=10600&p=271656&hilit=NRAC#p271656

Image


&
GRAPHIC: http://www.dtic.mil/cgi-bin/GetTRDoc?AD ... tTRDoc.pdf


I'm not in a position to argue the db figures above but from personal air show experience, the F-22 is very distinctive and audibly much louder 'sounding' than the F-16 or F-18. It isn't even close.
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Unread post04 May 2016, 22:45

That's the problem with standard measurements - they're standardized.

A-weighing takes a *normalized* human ears sensitivity into consideration. But this is a normalized response - no two set of ears are the same. Two different people may very well reach the opposite conclucions simply because they're sensitive to different frequencies.

Edit: Again, the slippery part... in this case, the F-16 and F-22 may very well have different spectrums that may hit you with the same energy, but at different frequency responses - making one sound subjectively louder.
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Unread post04 May 2016, 23:40

krorvik wrote:That's the problem with standard measurements - they're standardized.

A-weighing takes a *normalized* human ears sensitivity into consideration. But this is a normalized response - no two set of ears are the same. Two different people may very well reach the opposite conclucions simply because they're sensitive to different frequencies.

Edit: Again, the slippery part... in this case, the F-16 and F-22 may very well have different spectrums that may hit you with the same energy, but at different frequency responses - making one sound subjectively louder.

I think you might find this page quite interesting:

http://hyperphysics.phy-astr.gsu.edu/hb ... xsens.html

There you can see that certain frequencies are perceived as louder than others.

Image

The hearing curves show a significant dip in the range 2000-5000 Hz with a peak sensitivity around 3500 -4000 Hz. This is associated with the resonance of the auditory canal. There is another enhanced sensitivity region at about 13,500 Hz which may be associated with the third harmonic resonance of the auditory canal.


So for each jet you should have a graph of its sound spectrum and the equal loudness in phons with it. Then you will know how loud a certain jet is perceived for the average person. Just stating the sound level in dB will not give the correct data.
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Unread post06 May 2016, 11:34

botsing wrote:
krorvik wrote:That's the problem with standard measurements - they're standardized.

A-weighing takes a *normalized* human ears sensitivity into consideration. But this is a normalized response - no two set of ears are the same. Two different people may very well reach the opposite conclucions simply because they're sensitive to different frequencies.

Edit: Again, the slippery part... in this case, the F-16 and F-22 may very well have different spectrums that may hit you with the same energy, but at different frequency responses - making one sound subjectively louder.

I think you might find this page quite interesting:

http://hyperphysics.phy-astr.gsu.edu/hb ... xsens.html

There you can see that certain frequencies are perceived as louder than others.

Image

The hearing curves show a significant dip in the range 2000-5000 Hz with a peak sensitivity around 3500 -4000 Hz. This is associated with the resonance of the auditory canal. There is another enhanced sensitivity region at about 13,500 Hz which may be associated with the third harmonic resonance of the auditory canal.


So for each jet you should have a graph of its sound spectrum and the equal loudness in phons with it. Then you will know how loud a certain jet is perceived for the average person. Just stating the sound level in dB will not give the correct data.


Thats an audiogram from a healthy person with perfect hearing so yes, depending on acuity that recorded data will change .We do have to make a stand on a threshold level though and "perfect hearing" is the right measure , I wished my audiograms were this good! (Years of working around generators and engines has affected mine").
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