Sunday, September 23, 2012

F-35 Program Deputy Memo

Via Elements of Power’s Global Intel Network I’ve received the following memo. While we cannot completely ascertain its authenticity, the contents are hardly surprising or controversial. EoP offers the following as just another data point in the historical record of the journalism’s F-35 meme machine.

Internal F35 Program Memorandum
From: MG Christopher Bogdan
To: F-35 Teammates
Subject: AFA Statements 

Hi There!
Well by now I’m sure most of you have seen the reporting on my comments concerning the state of the F-35 program. I’m also pretty certain most of you have also figured out my motives for saying what I said, in the manner that I said it as well. But I want to be certain there are no misunderstandings between ALL of us on the F-35 team, so I’m going to describe what I said, and why I said it the way I said it, and do by covering my main points in as plain and clear terms as possible. Ready?

JSFPO-Contractor Relationship

When I said the relationship was the "worst I've ever seen" I meant it. But heck, even a wife-beater in his heart of hearts knows it takes ‘two to tango’ so while the press jumped on the statements as my telling the contractors to ‘shape up’, and just as I expected, think about it for a second: I’ve only been on board the program approximately two months. Two. Months. Two months on ‘the largest acquisition program ever’ is just about long enough to figure out there IS a problem and maybe get a feel for where my own side of the house is having problems. It’s certainly not long enough to determine root causes and failures. Even if I DID believe, as some claim, I single-handedly saved the KC-X  program, I STILL couldn’t possibly have enough chutzpa to think I had everything about the F-35 program ALL figured out in only two months. Rummage around in a few of those articles away from the headlines, and you’ll see I don’t lay the ‘relationship’ solely at the feet of any one group. After all it’s not like I can pretend there’s a surplus of experience and knowledge on the Government’s side of the relationship can I?

No More Money

No one in this business should be surprised the press has glommed on to the money angle: citing in their articles my point of having “no intention of asking Congress for any more money for the F-35 beyond what’s already in the pipeline”. While among us rational folks, that had to have come off as me just being “Major General Obvious” (Duh!) there IS method to my ‘madness’ as it were. This is the one comment that will buy me—our program—a little time out of the Petri dish to get our job done with minimal carping from the ignorant and uninformed. We will of course find the money we need that is already within the pipeline, and you can expect me to be open to suggestions in where to find it. Right now I just have a lot of questions and suspicions about things, such as perhaps those rather crudely constructed and outrageously high and unsupportable life cycle cost estimates. But in any case, WE will find a way. Even Major Generals can’t do it alone.

Technical Challenges

Make no mistake, we all know anything worth doing is never easy. If the United States and her International Partners didn’t NEED the capabilities the F-35 will bring to the Warfighter, we could have just squeezed a little more capability out of the basic legacy aircraft designs. By my acknowledging where we ALL already know where our challenges are and are actively working to conquer, when those successes come in the natural progression of time and engineering, WE will get credit for the accomplishments and blame for any shortcomings. It is an awful good thing we’re already well along in meeting those challenges, isn’t it?

Helmet Mounted Display (HMD)

The media still talks about the problems with the Helmet Mounted Display as if it were just found yesterday. That is to our advantage.  One would think that my mentioning the upcoming tests ‘in the next 60-90 days’ SHOULD tip them off that we believe our difficulties are substantially behind us:  just from our stating we are about ready to begin testing.



Since when is software not a challenge? It’s the ‘death and taxes’ of systems development: software is always HARD. Of course I mentioned it.

Complex Logistics

That I’m citing logistics as a ‘hurdle’ we have to overcome should have been another ‘No Duh’ moment. Think about it. NINE partner nations around the globe with Foreign Military Sales customers like Japan also coming on board. Eventually, the F-35 will have the global footprint of the F-16 or greater. That’s a lot of airplanes to support in a lot of different places. But the planes they’re replacing are in some cases more numerous and in all cases have more maintenance overhead. This means the entrenched government bureaucracy will be fighting tooth and nail to make the replacement F-35 workload grow to protect their so-called ‘core capabilities’.  We’re not only going to have to stand up a global support system, we’re going to have to do it while parts of the US Government are trying to squirrel some of it away and out of our control.

F-35C Tailhook

The tailoring of the F-35C tailhook redesign isn’t yet complete, but we’re going to complete the task pretty quick. While the usual Palestinian Apologists at Reuters will frame my statements as we ONLY caught the wire “five of the last eight times”, real journalists will pick up on the trend and recognize the trend is three of the last five, and the two that weren’t caught was because the pilot didn’t hit his mark.  Maybe the smarter ones among their readers will eventually figure out that unlike our test configuration, that’s the reason there’s more than one wire on the big deck carriers. 

That’s all for now, but I’m sure we’ll be communicating again real soon as part of improving our team communications which is in turn a critical part of rebuilding our team relationships.


Thursday, September 20, 2012

Achtung Lightning Und Spitfire!

This is the first of a couple of more light-hearted, but no-less relevant, posts I’m putting up before we close out the “F-35 High AoA” series. I just didn’t think these should wait.

Craig Hoyle at DEWLine Blog has a pic/’brief post’ up about the “UK Joint Strike Fighter Test and Evaluation Squadron” hosting a Battle of Britain commemorative event at Edwards AFB.

Hoyle poses a question:
An academic question, as there's no two-seater version of the F-35, but which aircraft would you rather fly in (not into combat, clearly)? As a Brit, it would have to be the R J Mitchell experience for me.

Hmmm. I wonder if he is aware that the ONLY two-seat Spitfires EVER built were conversions of existing airframes and not ‘production’ per se. (Do not doubt me on Spitfires). 

As of this time, Hoyle’s posted only one pic:

  (Credit All Photos: Matthew Short, Lockheed Martin)
Here are the other three shots of the past and future meeting:

The very large originals can be downloaded at the original article here.

Saturday, September 15, 2012

The F-35: What Will Happen While Exploring ‘High Angle-of-Attack’, Part 3

F-18 E/F: Heritage F-18 All Fixed, But….Surprise!

Part 3 in a series of posts where we document The ‘Profound Truth’ of High Angle-of-Attack (AoA) flight testing of high performance aircraft.

 The Profound Truth?

Discovery and rectification of undesirable aircraft behaviors during High Angle-of-Attack testing of High Performance Aircraft is not only the ‘Norm’, but those behaviors needing rectification/mitigation are usually complex, sometimes bizarre, and often ‘spectacular’.   

As in the F-18A-D post, we will avoid mentioning all other problems that the F-18E/F program dealt with that did not have to do with the AoA performance, behaviors and testing. They still would be helpful highlighting in yet another way: illustrating how the F-35 program isn’t as ‘concurrent’ as some would lead us to believe. But I’ll (again) resist the temptation to beat that ‘dead horse’.

The F-18E/F is ANOTHER excellent exhibit of the Profound Truth.

In closing Part 2, I observed that “many of the design objectives behind the F-18E/F were focused on eliminating the extant problems and limitations of the Heritage Hornets”. In Part 3, we will observe how an entirely new set of challenges emerged for the F-18E/F. I would call the challenges “problems” if we were all thinking like Engineers: “A problem is normal, something to be expected, and something to be solved”. But too many people seem to think a problem is a reason to NOT do something (as if there is such a thing as a ‘problem-free’ path in any worthwhile endeavor). On the topic of solving problems, engineers in any field know that it is almost always the case that a feasible solution will involve making ‘tradeoffs’. The F-18E/F, like the Heritage Hornet, was no exception to the rule. 

First, the specific design goals of the F-18E/F were:
1. Enhanced departure resistance and post departure (should it still occur) elimination of “falling leaf” or unrecoverable spin modes.
2. Requiring the aircraft to meet all flying quality requirements with a centerline fuel tank since this is a common operational configuration in all services, foreign and domestic.
3. Elimination of high AOA hang up and the accompanying AOA/cg restrictions.
4. The aircraft must be able to land on an aircraft carrier following most flight control failures.
5. Improved roll performance at elevated AOAs in the gear up/flaps Auto configuration.
6. Expanded tactical utility with large lateral store weight asymmetries (since high value stores are frequently deployed one at a time and can result in significant lateral weight asymmetries and aircraft maneuvering limitations after release of one store).
7. Reduction of likelihood of encountering pilot induced oscillation/aircraft-pilot coupling tendencies.
8. Adequate control following a dynamic and/or static loss of one engine (which sized the F/A-18E/F vertical tail).
9. No reduction in flight envelope for the two seat F model over the single seat E-model, since both aircraft would be mission capable aircraft. (Source: Hanley, Et Al, p. 32-6)
The F-18E/F program objectives Hanley describes were rather admirably met in the end, but Hanley also cogently summarizes the REALLY big surprise that the F-18E/F designers had to overcome.
Every flight test program encounters some “unknown unknown, “things that were not planned, thought of, or considered possible to occur in flight-testing. The Super Hornet was no exception. Early in the flight test EMD program, the aircraft experienced uncommanded “wing drop” during wind up turns and straight and level accelerations. As the program matured and the envelope expanded, it became clear that this was a serious problem that would impact aircraft performance if not corrected.
Over an eight-month period from August 1997 through March 1998, maximum resources were brought to bear to solve this problem. In all, over 10,000 wind up turns were executed on over 100 wing configurations before a solution was found. This effort required use of up to 4 of the 7 flight test aircraft to solve, causing significant rework to an already tight EMD schedule. The “wing drop” phenomenon was a rapid, uncommanded bank angle change of up to 180 degrees (if left unchecked by the pilot) that would cause a pilot to lose a guns-tracking solution on a threat aircraft. Wing drop occurred at all altitudes and from about 0.55 Mach to approximately 0.95 Mach. Extensive wind tunnel, simulation and CFD testing and analysis was conducted coincident with the flight-testing.
(Hanley Et Al, p. 32-8)
I’m told that the total time to ‘fix’ the problem was close to 3 years. The Hanley paper doesn’t quite get into the root cause, and the authors’ explanation of the “fix” is really a list of corrective actions progressively tried and applied:
Some of the flight test “fixes” assessed included modified snag locations, vortex generators, grit, stall strips, modified flap scheduling, control surface biasing, fences and porous wing fold fairing covers. Eventually, the porous wing fold cover proved to be the most effective solution to the “wing drop” phenomenon, by dissipating adverse pressure gradients fore and aft of the shock forming on the wing and reducing the effect of the asymmetric stall. 
There was an interim step to arrive at the ‘porous cover’ solution, whereby enterprising Navy types tried removing the wing-fold cover entirely, finding it pretty much fixed the ‘wing drop’ but created too much drag to meet other requirements. That’s when NASA stepped in with the half-way between 'none and one' cover, to make it a 'porous' cover. What the Hanley paper doesn’t really highlight at all is that the two factors that made this behavior SO alarming were 1) the abruptness of the phenomenon and 2) the apparent randomness of the direction the plane would roll.

What was it that happened between the Heritage F-18 design and the F-18E/F that brought about the entirely new undesirable behavior? Checking my notes from the aerodynamicist’s lecture I mentioned in Part 2, I find a pretty plausible explanation: ‘Better Idea Creep.’

Some ‘Better Ideas’, in the End… Aren’t

Initially, the F-18E/F was to be a stopgap (for the A-12 and/or later, the JSF). The initial concept was to simply scale up the wing and control surfaces about 25%, put fuselage ‘plugs’ in to increase fuel capacity and put bigger engines in the stretched fuselage to power it all.

The first ‘better idea’ came from the structure guys. They’d felt the Heritage F-18 wings weren’t quite rigid enough and wanted a less flexible wing. They sold the idea of increasing the wing thickness to improve stiffness and allow a lighter structural weight ratio as well as adding more fuel volume. The next ‘better idea’ came from the “systems guys” who sold the idea of reducing the proportions of the leading edge flap chord, which meant lower hinge moments, which allowed reuse of the Heritage Hornet actuator designs and save money. That move also meant even more fuel could be carried in the wings.

“We ‘Aeros’ put twist and camber in a wing for very good reasons. We don’t do it to irritate Structural and/or Manufacturing Engineers. It’s a ‘bonus’, but it’s not why we do it.” (To paraphrase a certain Aerodynamicist)

Early F-18E/F Modeling showed that simply scaling up the F-18C/D wing, with the original twist and camber, would increase supersonic drag and threaten the ability to beat the maximum time requirement for dashing from subsonic to supersonic. This brought about the next ‘better idea’: ‘straighten’ the wing to reduce supersonic drag. Straightening the wing was seen as beneficial in lowering manufacturing costs as well.

The next ‘better idea’, theoretically to improve resultant high lift performance, was to put a leading edge ‘snag’ at the outer third of the wing that would generate a vortex. This move was puzzling. As one of my ‘Aero’ lecturers noted: it didn’t work on the F-18A, so it was taken out of the C model. What made the designers think it was a good idea to bring it back? My lecturer observed that it was probably due as much to the design culture at Boeing née McDonnell Douglas St Louis, which has seemed to favor using leading edge ‘snags’ for decades (most prominently the F-4 Phantom).

The F-18E/F designers then also modified the LEX, but that was believed to more likely have been done to aid in eliminating the ‘alpha hang-up’ mode and increase ability to point the nose down in such an event. I should also add here that the E/F’s wing drop ‘fix’ of making the wing fold cover ‘porous’ is believed to have a supersonic drag penalty greater than there would have been if the designers had left the twist and camber in place.

All the successive changes didn’t trigger alarms in (the right) people’s minds that maybe the F-18E/F would no longer be quite as simple a derivative as it was first proposed. The F-18E/F did not have to go through nearly as many ‘wickets’ as a new-start program (GAO,1994). The wind-tunnel and computer simulation effort was not as thorough as a clean-sheet design (such as the F-35) would have executed prior to design freeze and manufacture. Only AFTER the F-18E/F was actually flying was the scope of the problem revealed. Not that a full wind tunnel and simulation would have helped. The Abrupt Wing Stall (AWS) program instituted after the F-18E/F wing drop made its self known required increased computing power and more detailed wind tunnel data to adequately examine the phenomenon.

What the wing design changes DID produce was an airfoil system that had a very steep pressure gradient with a propensity to abruptly (there’s that word again) move forward with massive airflow separation at only a moderate angle-of attack in the high subsonic speed range. Observe the flow patterns resulting from taking a baseline F-18C wing, and adding F-18E/F design features:
Source: “Introduction to the Abrupt Wing Stall Program”; Hall, R.M., Woodson, S.H.; JOURNAL OF AIRCRAFT, Vol. 41, No. 3; 2004.
The ‘red’ colors highlight the position, volume and amplitude of areas with REVERSE airflow and stall. What this phenomenon looks like on an actual F-18E is illustrated below in these snapshots taken from a video (Hall & Woodson):

Source: “Introduction to the Abrupt Wing Stall Program”; Hall, R.M., Woodson, S.H.; JOURNAL OF AIRCRAFT, Vol. 41, No. 3; 2004.
The lower photo shows a gap in the normal low pressure condensation making an intermittent appearance near the “wing drop angle of attack” (Hall & Woodson).

The ‘wing drop’ issue was probably the best known challenge the F-18E/F overcame, but there were some others “interesting” behaviors that had to be wrung out that the public never really heard about.

“Upright Coupled Departures”

Predicted modeling of a ”step left-and-full-aft stick command at 200 KCAS predicted a sharp left roll and pitch up into stall, a benign outcome”. The actual result provided the "most significant surprise of the program".
Within 3s[econds] of the input, the airplane rolled left, pitched up, and then departed nose right, going flat plate to the airstream in the negative direction. The resulting 3.7-g Nz exceeded the structural design limit, and the pilot’s helmet struck the canopy with sufficient force to leave an audible crack on the cockpit recorders….
…The next point was to have been 300 KCAS, doubling the dynamic pressure. Whereas the aircraft had tracked the simulation predictions earlier, this departure was completely unexpected (5 min earlier, the team had told the pilot that this would be a benign event). Departure testing was suspended for four months to allow for analysis, redesign, testing, and fielding of new FCS software
(Heller Et Al).
During the four month downtime, the F-18E/F team discovered that the “aircraft aileron power had been significantly underestimated” (by about ~20%), but most disturbing was that with this new information, the team could see that if they had proceeded with the 300 KCAS airspeed test point, they would have “exceeded the ultimate strength of the airplane” (Heller Et Al).
The ‘fix’ to this surprise was to make software changes that would ensure the roll authority would never exceed a value that would trigger the departure varying the roll rate possible by airspeed and pitch rates (upward). I think it was a rather elegant solution, even though it set the stage for further interesting behaviors. [As an aside, I also note here that while F-18E/F ‘Fans’ and the Boeing PR machine frequently tout the lack of an AoA limit on their ‘favorite’, they rarely mention, if they are even aware of, the flight control limits that ALLOW the unlimited AoA.]
“Our pilot laughed aloud at the sight of his own exhaust through the front windscreen.”

Engineers in the lab exploring the effects of the software ‘fix’ above found a “kink in the armor":
To avoid unnecessarily limiting roll rate, only a rapid aft-stick input in the presence of roll rate activated the clamp [Ed. a ‘software imposed limitation’]. Slower aft inputs were regarded as nonthreatening because of reduced susceptibility to inertial coupling. This assumption proved to be inaccurate. The simulator indicated that, in the presence of a full lateral stick roll, if the stick was brought to the aft limit in 3–5 s, an abrupt departure would occur. This prediction was passed to the test team to validate. The simulation was correct, with the most disorienting departures yet seen. Our pilot laughed aloud at the sight of his own exhaust through the front windscreen. (Heller Et Al)
This artifact of the previous ‘fix’ required the program make a decision: limit the plane or limit the pilots:
Because slow-aft departures were all occurring well after 360 deg of roll, and a fairly precise stick trajectory was required, the pilots decided that the conditions required to provoke this departure were sufficiently isolated such that degrading the roll performance would be unwarranted. A flight manual limit was imposed, identical to that on the heritage Hornet, restricting full stick rolls to 360 deg. (Heller Et Al)

“Flip-Flops” – A Spin on the Wild Side

Finally, A mode that manifested in a “significant minority of spins” was “a change in polarity” during recovery. An upright spin would suddenly flip to ‘inverted’, and inverted spins would suddenly flip upright. Viewed directly from above or below, the spin direction would not change, but from the pilot’s perspective, an upright spin to the right was now an inverted spin to the left.” Or vice versa (Heller Et Al). The ‘fix’ was made in the Flight Control System software to first recognize the ‘flip’ and then provide the pilot with correct display information to assist in the recovery.

To Summarize

There were a few other aero performance challenges the F-18E/F engineers and test teams discovered and overcame, but IMHO none as spectacular as those we’ve just covered. The F-18E/F was perceived as a ‘low-risk’ program containing evolutionary and NOT revolutionary advancements in Warfighter capabilities.
Yet incremental ‘tweaks’ to the design as it progressed added hidden departure modes, some of which at the time could only have been ‘discovered’ and not ‘predicted’.
While the F-35 benefits from advancements that High AoA research produced in the wake of the F-18E/F, the F-35 is a ‘clean-sheet of paper’ design and not a derivative of something else. The potential for unknown-unknowns is seen to be higher AND seen to be worth the effort.

Keep the F-18E/F lessons learned in mind the next time the legions of uninformed and/or irrational F-35 critics begin their silly chants. As my Aero lecturer was fond of saying: there’s a surprise hidden inside every airplane.


“Operational Lessons Learned from the F/A-18E/F Total Flight Control Systems Integration Process”; Hanley, R.J., Dunaway, D.A., Lawson, K.P.; NAVAL AIR SYSTEMS COMMAND PATUXENT RIVER MD, June, 2001.

 “Transonic Unsteady Aerodynamics of the F/A-18E Under Conditions Promoting Abrupt Wing Stall”; Schuster, D.M., Byrd, J.E.; JOURNAL OF AIRCRAFT, Vol. 41, No. 3; 2004.

 “F/A-18E/F Super Hornet High-Angle-of-Attack Control Law Development and Testing”; Heller, M., Niewoehner, R.J., Lawson, K.P.; JOURNAL OF AIRCRAFT, Vol. 38, No. 5; 2001.

“Naval Aviation: F/A-18 E/F Acquisition Strategy” (Letter Report, 08/18/94, GAO/NSIAD-94-194).

 “Introduction to the Abrupt Wing Stall Program”; Hall, R.M., Woodson, S.H.; JOURNAL OF AIRCRAFT, Vol. 41, No. 3; 2004.

Tuesday, September 11, 2012

"Barack Obama Told the Nation"

This was sent to me by a friend who is also in the 'Defense Industry'. Given the latest news on the Defense Sequestration found here, and here  for examples– I thought it apropos.

Barack Obama told the nation:
Have no fear of sequestration!
From EVERYONE, a Corp-o-ration ROBS!
Though I cannot say ‘twas really smart
RIF hundred thousands? - Just a start!
To ‘save’ Americans from... their jobs?

Now a homeless shelter resident

I oft’ wonder ‘bout the President,
Yeah I know Barack, he ‘loves’ me so.
Yet how sadly I remember
Way back yonder in November,
When he said my job would “never go”

Barack Obama told the nation
Have no fear of sequestration!
From EVERYONE, a Corp-o-ration ROBS!
Though I cannot say ‘twas really smart

RIF hundred thousands? - Just a start!
To ‘save’ Americans from... their jobs!!!!!?

C'mon and SING it!

NO apologies to JUST another aging Hippie that I’m waiting for to die off and who wrote the original "Lyndon Johnson told the Nation"

And then-- the 'idjiit' updated it with this:


Sunday, September 09, 2012

The F-35: What Will Happen While Exploring ‘High Angle-of-Attack’, Part 2

 “Heritage F-18: Surprise!”

Part 2 in a series of posts where we document 'The Profound Truth' of High Angle-of-Attack (AoA) flight testing of high performance aircraft.

 The Profound Truth:

Discovery and rectification of undesirable aircraft behaviors during High Angle-of-Attack testing of High Performance Aircraft is not only the ‘Norm’, but those behaviors needing rectification/mitigation are usually complex, sometimes bizarre, and often ‘spectacular’.
For this post, we will avoid mentioning all other problems the F-18 program dealt with that did not have to do with the High AoA performance, behaviors and testing. They would be helpful highlighting in yet another way, how the F-35 program isn’t as ‘concurrent’ as some would lead us to believe: but I’ll resist the temptation to beat that dead horse (this time).

The ‘Heritage’ F-18A/B/C/D provides an excellent exhibit of 'The Profound Truth'

The Heritage Hornet (F/A-18A thru D) was one of the ‘first-generation fly-by-wire (FBW)’ aircraft  developed in the 1970s. While other notable 1stGen FBW aircraft of the era (such as the F-16 and the Mirage 2000) employed AoA limiterswithin their control laws to avoid out-of-control-flight (OOCF) losses due to departure, spin, or deep stall”(Heller, Et al, 2001), it was found the Heritage F-18 did not need one….but only in a ‘clean’ (and therefore nearly useless militarily) configuration. High AoA testing revealed a design that would let the Blue Angels boggle John Q. Public’s mind with precise aerial displays, if you hung a weapons load with almost any real asymmetry the Max AoA allowable for the Heritage F-18 is reduced and other bad things happen:

Modest asymmetries increase the departure and spin susceptibility and come with undesirable fight manual limitations on the maneuverability. Large asymmetries impose severe limitations, which must be rigidly observed, thereby reducing the airplane’s safety and operational flexibility (Heller).

Well 'Connected' Vortex Flow
at Moderate AoA
The other really ‘big’ thing discovered in the YF-17/F-18A development effort was that the leading edge extension (LEX) has all sorts of advantages (up until it doesn’t). It generates vortices over the top of the wing and fuselage that increases lift at higher AoAs until it reaches a point where the AoA is so steep the vortices break down and turbulent flow takes over. The LEX was modified, ‘fences’ were added to help, but at Max AoA the sudden onset of turbulent flow beats up the vertical tails and knocks controllability out the window. Later, it was discovered that the tails took such a beating that the attachment points were reinforced with additional structure. (Aerospaceweb has an excellent short summary here.)    
As an aside, I must add that a detail design engineer on the F-18 program once noted in a lecture I attended that the early F/A-18 (Correction: YF-17) wind tunnel models shed verticals like crazy at high AoA. The model makers assumed it was the models’ fault, so they just built the models stronger. In retrospect, the wind-tunnel models were telling them something.

'Broken' Vortex & Turbulent Flow at
High AoA (NASA HARV Program
NASA got involved with fixing some of the Heritage F-18 ‘controllability problems’:   

In 1979, an F/A-18 test aircraft at Patuxent River suddenly and unexpectedly departed controlled flight during a wind-up turn maneuver at high subsonic speeds. None of the baseline wind-tunnel data predicted this characteristic, and the F/A-18 Program was shocked by the event. The fact that the free-flight model had also exhibited such a trend did not go unnoticed, and a joint NASA, Navy, and McDonnell Douglas team was formed to seek solutions with the free-flight model at Langley. Following exhaustive wind-tunnel tests in the Full-Scale Tunnel, the team recommended that the wing leading-edge flap deflection be increased from 25 deg to 34 deg at high angles of attack. Following the implementation of this recommendation on the test aircraft (via the flight control computers), no more departures were experienced, and the flap deflection schedule was adopted for production F/A-18’s. (Chambers, 2000)
Between late 1979 and end of Full Scale Development (aka FSD --closest corollary is today’s SDD) there were FIVE different series of F-18A/B’s control law changes. These major changes “…were incorporated in each of the major PROM series. Control law changes have been incorporated to improve handling qualities at all flight conditions (including high AOA and out-of-control), improve roll performance, reduce structural loads, improve departure resistance characteristics, incorporate and refine pilot relief modes, and provide an active oscillation controller to suppress undesirable in-flight oscillations.” (Kneeland et al)
Fortunately, these changes mitigated or eliminated most of the Heritage F-18’s early untoward behaviors, but one in particular remains to this day: the ‘Falling Leaf’ departure mode (aka ‘alpha hang-up’). The mode remains “suppressed”, but as the video below illustrates, still remains a threat to all but the most wary Heritage F-18 pilots.

Many of the design objectives behind the F-18E/F were focused on eliminating the extant problems and limitations of the Heritage Hornets.

Keep in mind the Heritage F-18’s discoveries when the rabid army of F-35 haters start sounding off.



“The Impact of the F/A-18 Aircraft Digital Flight Control System and Displays on Flight Testing and Safety”; Kneeland, B. T. , McNamara, W. G. , White, C. L.; NAVAL AIR TEST CENTER PATUXENT RIVER MD; 1983.
“Partners in Freedom: Contributions of the Langley Research Center to the U.S. Military Aircraft of the 1990's”; Chambers, J.R.; NASA SP-2000-4519; 2000.

“F/A-18E/F Super Hornet High-Angle-of-Attack Control Law Development and Testing”; Heller,M., Niewoehner, R.J., Lawson, K.P.; JOURNAL OF AIRCRAFT, Vol. 38, No. 5; 2001.

Saturday, September 08, 2012

The F-35: What Will Happen While Exploring ‘High Angle-of-Attack’


Oh Goody, Here Comes Yet Another Freak-Filled F-35 Hate-Fest (Part 1)

I first really noticed that the F-35B has been cleared to expand the flight envelope into the high Angle of Attack (AoA) regions, having successfully completed their ‘air-start’ test points, via Solomon over at SNAFU!

I knew the F-35A model had been trotting merrily along slightly ahead of the F-35B model (more ‘A’s, more flight hours, delivered earlier) and I thought I had read something somewhere about the ‘A’ also being cleared, so a little more digging in the usual places turned up the fact that yes, Dave Majumdar at Flight Global brought us the fact that the A model too has completed initial air-start test points; clearing the way for it to also begin ‘High AoA’ testing . There is also no indication which would lead us to believe the F-35C isn’t also keeping apace, so clearance flights for the C model should be expected in due time.   
I’ve thought about this upcoming phase of the F-35 testing a few times the last couple of years. Given how the usual F-35 ‘critics’ have gone into feeding frenzies over easily understood (by the uninitiated AND non-rabid) challenges and easily understood (by Ditto) corrective actions that the F-35 platform has dealt with/is dealing with, I am dreading the howls and shrieks that will certainly come when the F-35 encounters not-so-easily understood (by the uninitiated) surprises when it begins flying into the unknown ‘nooks and crannies’ of the flight envelope. Why?

Because strange, unexpected, and rarely subtle ‘surprises’ are ALWAYS encountered when high performance aircraft are first flown into those ‘nooks and crannies’.

The only differences between now and the past come from 
1. the evolution and elevation of the definitions of ‘high-performance’, ‘high AoA’ and ‘high-G’ and  in the F-35's case --
2.legions of know-nothings who don't understand the difference between 'test' and 'demonstration'.  

In this upcoming series of posts I will be arming the Rational among the Laity to help them subdue the rabid army of F-35 Haters when they turn-up their pitiful bleating. BTW: We are already seeing some indications the know-nothing clowns are laying-in-wait over (gasp) ‘buffeting’.

Unlike a lot of my multi-part series, these posts will be relatively short posts (hey! don’t sound so happy…) and I’m even telling you how many I’m planning and what their subtitles are ahead of time:

Part 2: “Heritage F-18: Surprise!”

Part 3: “F-18 E/F: Heritage F-18 All Fixed, But….Surprise!"

Part 4: “Old School F-15: Entry to the modern world of ‘High-Performance"

I've listed the F-15 last because it is in many ways the least relevant to the 5th Gen testing, but there are some observations to be made that are useful in showing all the challenges do not come from using Fly-by-Wire, nor are all the ‘fixes’ the same (or even ‘fixes’). I’m choosing to skip the F-16 for the moment because I’m thinking it will perhaps show up here and there in comparison with one or two other types in the list above.

Monday, September 03, 2012

Introducing Suzie Dershowitz Part 4

‘Provoking Accountability’…Of the ‘Unaccountable’ 


Defusing CATO’s “Precisely Guided Analytical Bomb”

Back to Part 3
POGO's Banner Carrier, Suzie Dershowitz. (Source: POGO)
Hopefully, this is the LAST time we'll be seeing her, but don't bet on it.

(To make each segment better as a ‘standalone’, I'm getting a little repetitive at the start of each post. If you’ve been following the segments all along, you may proceed to the subheading “CATO/POGO: Fuller Multiplier is an Outlier!” without missing the heart of the post.

Major Ploy Du Jour #2 (Continued):

“This Proves/Refutes Our POV/Their POV” (In this case both). Only.... it doesn't. Hint: You could lay all the economists in the world end to end and you still wouldn't be able to reach a conclusion.
As we noted in Part 3:  

“…for this exercise we will focus on problematic areas of the CATO analysis (because it is not a study, but is merely an analysis that is critical of the Fuller study) where Ms. Dershowitz unwisely attempts to use in support of her assertion that ‘left, right, and center’ agree with POGO: that there will not be the kind of damage that the industry-sponsored study warns us will happen.”
 As we also noted in Part 3, there are two aspects of the CATO analysis upon which POGO relied as evidence ‘supporting their position’. These perceived points of ‘support’, unfortunately for POGO do NOT provide the support they claim. 

We exposed POGO/CATO’s Fatal Flaw #1 in Part 3 by illustrating CATOs critique of the Fuller study’s methodology amounted to no more than a pique over academic taste. The CATO complaint over the Fuller Study not going further than it was designed to do, and not doing anything other than that needed to achieve its intended explicit objective was rather sad. Claiming the Fuller study should have been burdened with additional layers of abstraction to answer a question different from the question asked, with the claim rationalized by the unsupported assertion that it would have been more meaningful, all without adequately describing the specific controls (ground rules and assumptions), modeling, or processes involved, seems to be rather self-serving caviling.

In closing Part 3 and in preparation for this segment, I asserted:          
I believe the CATO players fully understand the notion of ‘usefulness’, and that it wasn’t enough to claim their study was more useful, when at best it is perhaps useful in a different way, and at the worst less than helpful through introduction of excessive ambiguity. What MAY explain why CATO went to great lengths to employ (and POGO parroted) the complaint that the Fuller study ‘didn’t go far enough’ is that they sought to use it as a smokescreen to cover their more ‘tangible’ complaint that Fuller overstates the net economic ‘multiplier’ of defense acquisition spending. Strip away the ‘Fuller didn’t take into consideration X,Y,and Z’ obfuscation and CATO’s weak attempt to ‘sell’ the idea that Fuller’s multiplier was outside some ‘economics mainstream’ not only looks even weaker, but intentionally contrived (more on that later).   
By using CATO's own references, I will show how CATO not only does not show the Fuller multiplier lies outside some contrived norm, but they actually lend support to idea that the Fuller multiplier is possibly more appropriate than either the Economic Aesthetes at CATO or the Progressive Proles at POGO would have us believe.
Thus, on this adventure, we will cover Fatally-Flawed POGO/CATO Point #2.

2. Dershowitz/POGO relies on CATO claims (and claimed ‘evidence’) that the Fuller study overstates the net economic ‘multiplier’ of defense acquisition spending.

 CATO/POGO claim: Fuller Multiplier for Defense Spending is an Outlier!

CATO asserts, and POGO’s Dershowitz promotes the notion that the Fuller study used an inflated ‘multiplier’ for arriving at the economic impact values for reduced defense spending. 

CATO Analysis:
 The Fuller analysis summarized above suggests a GDP multiplier effect of 1.92 for 2013 as a result of a $45 billion reduction in defense procurement. The modern scholarly literature on the GDP effect of government spending growth casts significant doubt on any multiplier effect of that magnitude, even under the assumption that the concept of a multiplier effect is consistent with sound economic analysis. 

POGO’s Dershowitz claim: Fuller Is (Gasp) “Overblowing”!

POGO’s Dershowitz applies a blatantly biased spin on the CATO claims: Thus, it appears that Fuller is overblowing the impact of defense spending on GDP by almost twice as much as other estimates. The table in Zycher's analysis (reproduced below) provides a visual representation demonstrating just how out of sync Fuller's study is…
Ms. Dershowitz was kind enough to replicate the CATO table involved:

defense procurement
Cogan et al.
large stimulus
Mountford and Uhlig
spending "shock"
Barro and Redlick
increases in defense spending
Ramey (2011)
defense spending after WW2
all government purchases
defense spending
Ramey (2012)
all government spending

Let’s look at these comparative references just a little closer, to see “how out of sync Fuller's study is” shall we?

The Cogan, Et Al. Paper

The first reference we’ll look at is Cogan, Et Al. The title, “New Keynesian versus Old Keynesian Government Spending Multipliers”, gives us a fairly good indicator the paper itself presents.
From the abstract of the paper, we see that the thrust of the analysis is not only just about “New vs. Old” Keynesian modeling, but also about how those models apply to estimating the effects of one of the recent, large, so-called “Economic Stimulus” packages (You know – the ‘stimulus’ packages…that weren’t):
Renewed interest in fiscal policy has increased the use of quantitative models to evaluate policy. Because of modelling uncertainty, it is essential that policy evaluations be robust to alternative assumptions. We find that models currently being used in practice to evaluate fiscal policy stimulus proposals are not robust. Government spending multipliers in an alternative empirically-estimated and widely-cited new Keynesian model are much smaller than in these old Keynesian models; the estimated stimulus is extremely small with GDP and employment effects only one-sixth as large and with private sector employment impacts likely to be even smaller.
If that isn’t bad enough, the ONLY place the .65 ‘multiplier’ figure of merit proffered by CATO and repeated by POGO has nothing to do with defense spending:
 In any case, by assuming that the impact on consumption of the extra 1 percent discretionary increase in the deficit is .3 percent of GDP and using the above mentioned multiplier of .63 the impact will be to increase GDP by an additional .19 percent. If we add this to the .46 percent GDP increase from purchases, the total impact will be to increase GDP by.65 percent in the fourth quarter of 2010 compared to what it would otherwise be (P.17).
In fact, the words ‘defense’, military, or even ‘durable goods’ appear nowhere in the paper. It is a Keynesian modeling love-fest that lumps all government spending in one bucket from what I can tell. Interestingly, the focus is on the impact of adding new generic government spending with all sorts of multiplying effects versus estimating the negative impact (shock and long term) of suddenly withdrawing funds which would impact innumerable and ongoing economic activities. This point is even acknowledged in the text of the CATO paper (p.6):
”Cogan et al. estimate an effect of only about 0.65 in the quarter with the highest impact of a large government “stimulus” policy, which obviously differs from a change in defense spending alone”. 
How typical of POGO to NOT mention that little quirk behind the entry in the nice shiny ‘table’ they hold up as an example. 

BTW: If you like the back and forth of Keynesian economic model arguments (I don’t) you can always pull this thread and see where it takes you.

The Mountford and Uhlig Paper 

In  the Mountford and Uhlig reference CATO is again forthcoming in the text about what the .65 multiplier means (p.6):
“Mountford and Uhlig, employing a different type of economic model, arrive at a very similar finding of 0.65 in the first quarter of a spending shock financed with debt.”
 More specifically, the Mountford and Uhlig source document reveals the .65 figure in a table, and in the note below that table we find:
 “This table shows the present value multipliers for a deficit financed tax cut policy scenario and for a deficit spending fiscal policy scenario.” 
The entire thrust of the Mountford and Uhlig study is to characterize the effects of deficit spending overall – NOT what is the economic impact of defense spending. At least the Mountford and Uhlig study indicates that ‘Defense’ spending was accounted for in the overall lump of government spending (p.26), but we have no way of knowing whether or not the multiplier of defense spending alone is above or below the ‘.65 average’ modeled for ALL spending.

The Barro and Redlick Paper

At least this academic exercise in economics attempts to deal with the defense outlays, but by its own internal observations acknowledges several problematic aspects that call into question any direct comparison with the Fuller study. The two largest IMHO:
1. The authors state from their review it is their opinion that “It seems unlikely that there is enough information in the variations in defense outlays after 1954 to get an accurate reading on the defense-spending multiplier” (pg 4). Unless the CATO authors assert that there is no material differences between the economy of today and the US economy prior to the Korean War, which would be wrong, (see my post on the 50th anniversary of Eisenhower’s now-mythic Military-Industrial Complex speech ) this would seem to automatically preclude relying on this study to evaluate the Fuller report, even if it agreed with the Fuller defense multiplier.

2. The author’s abstract contains the assertion: “For U.S. annual data that include WWII, the estimated multiplier for defense spending is 0.6-0.7 at the median unemployment rate. There is some evidence that this multiplier rises with the extent of economic slack and reaches 1.0 when the unemployment rate is around 12%.” Since the paper’s median unemployment rate is 5.57% (pg.18), and we are in fact experiencing much higher unemployment rates at the moment (as high as 14.9% if you counted unemployment like we did back in the years this study analyzed)  , the question becomes would the authors’ assertions that the defense multiplier would cap at ‘1’ hold in today’s economy?

Answer: We don’t know from the data presented.

The Ramey(2008)and Ramey(2011)Papers

All we (the Public) have to go on concerning Ramey’s 2008 paper is the abstract which claims:
The implied government spending multipliers range from 0.6 to 1.1. 
…and the CATO Analysis observation within the text which claims Ramey(2008) “finds a defense multiplier effect of 0.6 to 0.8 for the period after World War II”.
That last bit is interesting. I wonder how that statement is reconciled with Barro and Redlick’s observation above—the point that being able to determine the multiplier after 1954 was ‘unlikely’?

By now, the reader should have gotten the idea that with models and the right ground rules, these studies will find whatever the authors want them to find. 

The CATO analysis claims Ramey(2011) “finds a GDP multiplier from all government spending of about 0.5”. Well, we’ve already covered the point that ‘all government’ spending does not equal ‘defense spending’, so what is CATO’s point other than attempting to ‘pile on’?
In reviewing the papers we’ve covered to this point, I’ve even found reference to dominating influences of state and local government spending in the ‘all government’ spending equation after the middle of the last century (No, I’m not going to reread them all again to find it for a link). That aspect muddies the waters even more.

The Parlow (Ahem) Paper

When I first read this paper my first thought was: WTFO? But the author apparently isn’t a functional illiterate, but instead a German studying for his Econ PhD in the US. Apparently no one proofreads his work. Once you get past the poor grammar, you find little more than a ‘this is how I used the models and made them work using fake expenditures and wars’ discussion.
The author claims that his analysis, using quarterly data vs. annual data, is a ‘better’ approach than the norm. Apparently the author is unfamiliar with how long it takes to invoke a change in defense acquisition or see the impacts thereof.
The author, as noted in the CATO/POGO table, claims ZERO economic effect from defense spending. There is no account provided for how the author actually handled the “all other things held constant” economic variables. But if I knew more about this paper, I would probably encourage the reader to also take a look: for it reeks of classic GIGO. As it stands, I wouldn’t recommend it to anyone, and it makes me wonder if CATO was THAT desperate to come up with a longer table for their pagination and printing purposes rather than content.
With the claim of ZERO impact from defense spending (the only one in the list), what makes this Parlow paper NOT the outlier compared to all others in CATO’s eyes?

Finally, The Hall Paper

This is another one that the web provides only the abstract on this side of firewalls [bold emphasis mine]:
During World War II and the Korean War, real GDP grew by about half the amount of the increase in government purchases. With allowance for other factors holding back GDP growth during those wars, the multiplier linking government purchases to GDP may be in the range of 0.7 to 1.0, a range generally supported by research based on vector autoregressions that control for other determinants, but higher values are not ruled out. New Keynesian macro models have multipliers in that range as well. On the other hand, neoclassical models have a much lower multiplier, because they predict that consumption falls when purchases rise. The key features of a model that delivers a higher multiplier are (1) the decline in the markup ratio of price over cost that occurs in those models when output rises, and (2) the elastic response of employment to an increase in demand. These features alone deliver a fairly high multiplier and they are complementary to another feature associated with Keynes, the linkage of consumption to current income. Multipliers are higher—perhaps around 1 .7—when the nominal interest rate is at its lower bound of zero, as it was during 2009
In fairness, the CATO analysis mentions Hall’s reference to the multiplier moving to the higher end of the range as interest rates approach zero included (pgs 6-7). POGO’s Dershowitz conveniently omits that fact in her little hit-piece. If one would care to review the current rate at which the Government can borrow, one would find it much closer to zero than I think any other time I’ve seen in my adulthood (.25%--a quarter of one percent at this time). Which brings us to observe, that even without necking down the dollars in Hall’s paper to just Defense spending, the Hall paper’s findings are not very far apart from the Fuller report’s multiplier.

By CATO’s own reference to Hall, they prove that while Fuller may be on one side of a range of modeled results, the Fuller Report is NOT an ‘outlier’ by any means.


The assortment of studies that the CATO authors rounded up and how they applied them reeks every bit of the sort of advocacy research that they attempt to claim is a fault of the Fuller report. For about the last decade and a half (or so), when I read this sort of advocacy masquerading as analysis I mentally file it under a category named for the first half of the title of a favorite paper: A Precisely Guided Analytical Bomb.