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Unread postPosted: 02 Jun 2012, 03:21
by archeman
Wow you guys had 'clean' rags down under? Luxury.

OK one more story about why hydraulic fluid gives me the shivers, then I'll shut up for now.

One rainy day working with a new guy we were doing a checkout of a couple if items and he failed to tighten something correctly on a hydraulic system above us (not uncommon - sealing the systems correctly is part skill, experience, luck and voodoo magic). Many of the leaks won't leak at all until you put that portion of the system under load for a while then shake the assembly abit. In the rain we didn't notice that some of the liquid coming down was red. I only got soaked on the arms but he was soaked right through jacket, thermal liner, bdu shirt, tee shirt to the skin. Nasty stuff. It's so oily slick and doesn't behave like water so it can drip on you without you even feeling it. Afterwards the only thing you can do with those clothes is burn them. SAC didn't accept showing up for duty wearing oily rags.

Go Electrons! :wink:

Unread postPosted: 02 Jun 2012, 03:55
by spazsinbad
I thought of stating truthfully 'clean oily rag' but did not want to disrespect our fine RAN FAA Maintainers. :D

The A-4 Skyhawk has an AFT (worse) and FWD [under fuselage] 'HELL HOLE' where such drips from all kinds of fluids were a real hazard. A nightmare if engine running!

Unread postPosted: 02 Jun 2012, 04:33
by spazsinbad
Some more 'dual' EHA specific info from previously mentioned PDF on previous page....

AIRCRAFT SURVIVABILITY Spring 2012 ... V9_web.pdf (2Mb)

JSF Full Up System Level Testing F35 Flight Critical Systems Test by Chuck Frankenberger

...FCS Architecture : No cheap Kills
One of the newer technologies in the F35 is the Electrohydrostatic Actuators. These actuators contain a self-contained hydraulic system. There are two types of actuators on the aircraft: simplex and dual tandem. The dual actuators have redundancies built in, including dual communication and power paths. The dual actuators were ballistically tested and showed good tolerance to damage. The redundant systems are isolated, and damage on one side did not propagate to the other side....

The FUSL testing conducted on AA-1 was very successful meeting all defined test objectives and success criteria. Addressing synergistic effects, the electrical power and flight control systems successfully isolated failures and protected the redundancies built into these systems, allowing continued safe flight. The VSN architecture is robust, providing multiple paths to transfer data. Testing highlighted that fire is a significant threat to flight critical systems.

The test team was able to verify that the actual ballistic damage response correlated very well to previous pilot in the loop simulator testing. Over the course of the test program, the LFT team witnessed firsthand the robustness of the F35 flight critical systems, no cheap system kills."

Unread postPosted: 02 Jun 2012, 05:16
by popcorn
So, is it safe to say that this tech will be the norm, from now on for military aircraft?

Unread postPosted: 02 Jun 2012, 05:20
by spazsinbad
Unless it turns out not to be? :D I can only view the past.

Unread postPosted: 02 Jun 2012, 06:17
by popcorn
spazsinbad wrote:Unless it turns out not to be? :D I can only view the past.

Well, I'm wondering how long it will take the Russians and Chinese to switch to the new tech?

Unread postPosted: 02 Jun 2012, 22:18
by sferrin
popcorn wrote:
spazsinbad wrote:Unless it turns out not to be? :D I can only view the past.

Well, I'm wondering how long it will take the Russians and Chinese to switch to the new tech?

If China does't already have them in production (down to the serial numbers) it'll just be a matter of time. They undoubtedly have the CATIA files.

Unread postPosted: 02 Jun 2012, 22:48
by VarkVet
ElectroHydroStatic Actuators ... I like them already because it sounds like a Pointy Head function to R2 :lol:

Re: ElectroHydroStatic Actuators

Unread postPosted: 24 Aug 2016, 03:09
by spazsinbad
2 page PDF with this info attached.
"Moog was selected by Lockheed Martin as the system integrator for the Primary Flight Control and Leading Edge Flap Actuation Systems on all three variants of the F-35 Joint Strike Fighter. Rolls-Royce also selected Moog to design, qualify and manufacture the Lift System Primary Actuation for the F-358 variant.

Flight Control Systems
The F-35 "power-by-wire" system represents an advancement on the more electric aircraft topology, integrating:

Self-contained electrohydrostatic (EHA) actuators to position primary flight surfaces
Electronic control units to remotely drive and control the EHAs
Electrically driven power drive units (PDUs) to position the maneuvering leading edge flaps

As the prime contract holder, Moog's role includes managing the industry team, integrating the complete actuation system and supplying critical technologies and major sub-systems.

While not part of the flight control system, Moog also developed the wingfold actuation system for the carrier variant, which includes Moog's advanced spline lock technology.

Lift System Primary Actuation
The hovering ability of the F-35B STOVL aircraft is provided by the lift system, which combines a thrust vectoring nozzle that directs main engine exhaust downward to generate aft vertical lift, and a centrally mounted lift fan to counterbalance forward vertical lift. Moog supplies the lift system primary actuation, which includes:

The actuation system for the three-bearing swivel nozzle, which is rotated 90 degrees, directing the main engine's exhaust downward

The actuation system for the lift fan's variable area nozzle and inlet guide vane, which controls airflow through the lift fan These actuation systems use electronically controlled hydraulic and fueldraulic servoactuators specially designed for operation in extreme temperature and vibration environments.

Power-By-Wire Architecture
1 Power and Control Electronics; 2 Electric Power Drive Unit; 3 Dual Tandem EHA Actuator; 4 Simplex EHA Actuator; 5 Flap Actuation System; 6 Wingfold Actuation System

Advanced Fueldraulic System
1 Variable Inlet Guide Vane Actuation; 2 Variable Area Vane Box Nozzle Actuation; 3 Three-Bearing Swivel Module Actuation; 4 Transfer Gearbox; 5 Nozzle Cooling Valve Actuator

Source: ... un2012.pdf (2.3Mb)

Re: ElectroHydroStatic Actuators

Unread postPosted: 24 Aug 2016, 03:37
by spazsinbad
F-35 Lightning II Flight Tests
15 Jun 2007 Eric Hehs

"...The electro-hydrostatic actuators, or EHAs, are another excellent example of risk reduction we're accomplishing on AA-1. This is the first real electric jet. The flight control actuators, while they have internal closed-loop hydraulic systems, are controlled and driven by electricity—not hydraulics. The F-35 is the only military aircraft flying with such a system. We proved that the approach works on six flights of the AFTI F-16 during the concept demonstration phase of the JSF program. We already have many more flights on EHAs on this test program. Because we are flying production versions of the EHAs on AA-1, we won't have to prove the EHA design on subsequent F-35s...."


Re: ElectroHydroStatic Actuators

Unread postPosted: 24 Aug 2016, 04:05
by spazsinbad
This info is probably repeated elsewhere but anyway thanks to the current Oz Gubment and my slow internet that likely will not be improved by the really crappy to be NbN (care current GuBment PM) I'm gonna have to say sayonara for a bit but....
Up in the Air: Understanding the F-35 Air Vehicle
11 Jun 2015 Fort Worth, Texas LM

"...The F-35 is unique in that it is the first time Electro Hydrostatic Actuators (EHAs) are being used as primary flight controls in a fighter aircraft. “Primary flight controls” refer to the rudder, horizontal tail, and flaperon control surfaces that control the jet’s flight.

“Some commercial airliners have backup EHAs, but the F-35 is really the first use of EHAs as primary flight controls,” Angela elaborates.

Angela, who specializes in EHAs, explains that an EHA is a compact, self-contained hydraulic unit. In Legacy fighters like the F-16, a centralized hydraulic system uses pressure to push fluid out to extremities of the aircraft, which in turn moves an actuator—a rod—that controls movement of a specific surface.

However, with this significant tubing running to all ends of the jet comes potential hydraulic fluid leaks and extra weight. Additionally, any type of aircraft maintenance requires full depressurization of the hydraulic system.

In the F-35, each surface is controlled by one EHA unit—no centralized system is needed.

Instead, power from the aircraft is funneled to Electronic Units (EUs) that power individual EHAs to move the flight control surfaces. Adrian explains why this presented a particular engineering challenge.

“The question became: ‘How do we build hardware that will withstand what we’re asking it to do using electrical power driving an actuator that has not been done before?’ Having a large amount of power going in and out of a small box is not something trivial to figure out.”

Since EHAs are self-contained, maintenance only requires the removal or repair of a single unit, say, beneath an F-35 horizontal tail. The potential for hydraulic fluid leaks is minimized and extra tubing weight is eliminated.

EHAs are single units, but they are substantial. In fact, some in the F-35 are as large as a tabletop and weigh 200 pounds. Each EHA must be powerful enough to overcome aerodynamic forces as it drives its surface into the wind flow...."

Source: ... ir-vehicle