F-35A versus Saab Gripen NG

[Conan]

LMAO,

Conan and Casey, BOTH of ya are wrong!

F-35 is NOT a replacement for F-117 as F-35 will not be operational for another 6 years!

And F-22 is currently NOT a replacement for F-117! That is, until it finally gets it's long-awaited FLIR/laser designator it was designed for.. If you concur however, that F-22 should be funded for this long-awaited upgrade, then I'll give you the comparison.

But perhaps all of us can agree that F-117 not only should have NOT been retired as it was, but in fact should have actually continued in production (VERY CHEAP units), and further upgraded with off-the-shelf tech as it was originally designed with for economical, fast development! Wow!

Heck, perhaps today such an expanded production fleet of F-117s could have even been updated for future UCAV duty, thus saving an additional $20-30 billion R&D for future LO UCAV substitute?!?

Whether one AGREES with the idea or not, the F-22 HAS physically replaced the F-117 within USAF...

http://www.f-16.net/news_article2040.html

[SpudmanWP]

einstein is right

No he is not... and for several reasons:

1. He has no experience with the hardware on the F-35
2. He has no idea how the F-35 handles cooling issues
3. He assumes that LM would bet the farm on technology that it had not thoroughly tested under flight conditions
4. He provides ABSOLUTELY no sources that state the F-35 is having any kind of heat-related control issues, or any other kind of control issues.

Oh yeah... one final thing. The EHAs in the F-35 are production units. That means FULLY tested to perform in all the aspects of the flight envelope.

[Conan]

A fan of the Air Power Australia school of thought are you?

Still your facts are wrong. It is not replacing the F-117. The F-22 has.

It is not replacing the Strike Eagle. Nothing is yet.

And it can climb, turn and run as well as any 4th Gen fighter. Just because Dennis Jensen and Peter Goon say it can't doesn't make it so.

Nope, I'm not an Aussie. The F-22 can't replace the F-117, its systems are not suited to ground attack, and it can't take enough bombs to function as well in the bomber role as the F-35. When the F-35 is available, it will take over the F-117's tasks. The Strike Eagle wil of course be in operation for many years, but the F-35 will take over some of the more demanding tasks.

Maybe you could mention that to the 7th Fighter Squadron. I'm sure they'll be interested to hear why the F-22 can't replace the F-117...

The F-22 can carry 2x bombs internally, right?

How many bombs internally could the F-117 carry? I'm pretty sure it was two wasn't it?

That's some fine arguing there mate...

[Casey]

1. What question?

My implied, and other's, question is that you back up such an statement with CREDIBLE sources.

Two officers within the JSF-progrm not credible?

2. Do you have a history of attacking persons instead of debating the case?

I think you have me confused with someone else. If you have read my posts, I take a lot of time searching the net for CREDIBLE sources for what I say and I provide those links for other to read.

You DEFINETLY have a history of attacking people, insead of sticking to the case!

[Casey]

Did I really mention Rand at all?

Sorry... Fat finger. Not RAND.

I hereby retract my retraction

It was a RAND study, weather you said it or not.

The study is downloadable here and there is an article from Flightglobal where RAND says the following:

Rand has disavowed the critical remarks about the F-35 as not intended for public release and, unlike the main presentation, not peer-reviewed. Additionally, Rand says: "Recently, articles have appeared in the Australian press with assertions regarding a war game in which analysts from Rand were involved. Those reports are not accurate. Rand did not present any analysis at the wargame relating to the performance of the F-35 Joint Strike Fighter, nor did the game attempt detailed adjudication of air-to-air combat. Neither the game nor the assessments by Rand in support of the game undertook any comparison of the fighting qualities of particular fighter aircraft."

I DEFINETLY did NOT mention RAND, my conclusion is based on what I have been told by american officers.

[Casey]

rapier01 just posted a link to a great interview with the first pilot of the F-35..if you [wink]choose[/wink] to believe him.

His job to the public is----MARKETING! Citing LM's marketing people as a credible source?

[Corsair1963]

Did I really mention Rand at all?

Sorry... Fat finger. Not RAND.

I hereby retract my retraction

It was a RAND study, weather you said it or not.

The study is downloadable here and there is an article from Flightglobal where RAND says the following:

Rand has disavowed the critical remarks about the F-35 as not intended for public release and, unlike the main presentation, not peer-reviewed. Additionally, Rand says: "Recently, articles have appeared in the Australian press with assertions regarding a war game in which analysts from Rand were involved. Those reports are not accurate. Rand did not present any analysis at the wargame relating to the performance of the F-35 Joint Strike Fighter, nor did the game attempt detailed adjudication of air-to-air combat. Neither the game nor the assessments by Rand in support of the game undertook any comparison of the fighting qualities of particular fighter aircraft."

I DEFINETLY did NOT mention RAND, my conclusion is based on what I have been told by american officers.

What American Officers?

[Corsair1963]

rapier01 just posted a link to a great interview with the first pilot of the F-35..if you [wink]choose[/wink] to believe him.

His job to the public is----MARKETING! Citing LM's marketing people as a credible source?

Well, what is your source???

[SpudmanWP]

Two officers within the JSF-progrm not credible?

No, not without public statements by those officers. Otherwise, anyone can say anything.

I DEFINETLY did NOT mention RAND, my conclusion is based on what I have been told by american officers.

I did not say that YOU SAID it was the RAND study, I just stated that the info came FROM the RAND study. You quote of ‘can’t turn, climb or run’ is a DIRECT quote from slide# 80 downloadable here

His job to the public is----MARKETING! Citing LM's marketing people as a credible source?

No, his job is an USAF officer and pilot. He does not work for LM. Are you saying that all USAF personnel that have worked on the F-35 cannot be trusted? Then how do we trust your un-named and un-quotable USAF personnel?

btw, That RAND study is using Janes info only, no inside information. If you do not mind, I will put my trust in the people who actually fly the F-35.

[einstein]

einstein is right

No he is not... and for several reasons:

1. He has no experience with the hardware on the F-35
2. He has no idea how the F-35 handles cooling issues
3. He assumes that LM would bet the farm on technology that it had not thoroughly tested under flight conditions
4. He provides ABSOLUTELY no sources that state the F-35 is having any kind of heat-related control issues, or any other kind of control issues.

Oh yeah... one final thing. The EHAs in the F-35 are production units. That means FULLY tested to perform in all the aspects of the flight envelope.

I´m right about the simple basic formula fact, that EHA´s produce a lot of heat if operated
as in a fighter and there is no liquid cooling circuit as in X-35
You are right, that I don´t know how LM is handling this problem, but suppose it´s done like in B-787 with EHA´s, you fly like an airliner
Joined a SAE Fluid Power meeting with presentations of X-32 and X-35, actually the same
day as LM was chosen for F-35 and for which - USAF had demanded - EHA´s
The Boeing man said they had refused to do that in a fighter and he had a lot of more reasons not to do that, but it gets too hydraulic, my point is that you basically can´t be a fighter with hot and slow EHA´s

[SpudmanWP]

there is no liquid cooling circuit as in X-35 .... my point is that you basically can´t be a fighter with hot and slow EHA´s

The F-35 will use the fuel as a liquid cooling mechanism. There is a large heat-exchanger in the inlet channel for this purpose. And as we all know.. the F-35 has plenty of fuel

LM has been testing EHAs since 1996. These are not commercial models. They are MILSPEC. I am confident that LM fully planned for the heat buildup in the EHA.

(From Code One article) "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."

[einstein]

there is no liquid cooling circuit as in X-35 .... my point is that you basically can´t be a fighter with hot and slow EHA´s

The F-35 will use the fuel as a liquid cooling mechanism. There is a large heat-exchanger in the inlet channel for this purpose. And as we all know.. the F-35 has plenty of fuel

LM has been testing EHAs since 1996. These are not commercial models. They are MILSPEC. I am confident that LM fully planned for the heat buildup in the EHA.

There is no liquid cooling from- the actuators - like in X-35 that had a centralized hydr system, where the hot fluid was going back to a fuel heat exchanger

Boing 787 EHA´s are in principle and regarding heat loss the same, an electric motor a pump in a package

You fly like an airliner, EHA´s will be fine

[SpudmanWP]

Dude… Do you even know what Google is??? I have to wonder. A few minutes searching for info here, came up with plenty of info.

1. Here is the specific info on Parker’s (Actuator Contractor) EHA Spec for the F-35.

F-35 Fighter incorporates EHA. (Ideas & Applications).
Source: Hydraulics & Pneumatics
Publication Date: 01-DEC-02
The new Lockheed Martin F-35 Joint Strike Fighter's flight controls will use electrohydrostatic actuation (EHA) technology for the first time in a production aircraft. Parker Aerospace Control Systems Div.-Military and Moog, Inc. are jointly designing and developing the primary flight control actuation system The Parker/Moog team is also responsible for power drive electronics on all three variants of the F-35.

The EHA technology provides several benefits. The actuators are smaller and weigh slightly less; performance is more efficient, and the F-35 is less vulnerable to enemy fire.
The 4000-psi EHA actuators have flow capabilities up to 26 gpm, depending on the surface. There are two basic configurations: a simplex configuration (rudder and aileron) and the dual-tandem (horizontal tail and flapperon).

These sophisticated actuator packages contain the following:
* a ram assembly with triple-redundant rod seals to minimize leakage,
* an integral triplex-ram LVDT,
* a liquid-cooled DC motor with integral resolver,
* a bidirectional shoeless pump -- capable of speeds to 15,000 rpm,
* a metal-bellows reservoir with level sensing,
* pilot-actuated solenoid valves to control mode logic (one spool-in-sleeve logic valve for the simplex version, three for the dual-tandem version),
* anti-cavitation check valves,
* control-pressure relief valves,
* fill and bleed ports,
* control-port and reservoir pressure transducers, and
* motor-coil and reservoir temperature transducers.

Wow, look at that… it has liquid cooling and specifically addresses thermal issues. Who would have thought???

2. Parker has stated

Electrohydrostatic actuation (EHA) is a power-by-wire system that eliminates the need for central hydraulics. EHAs are self-contained hydraulic systems controlled by high power electronics, allowing the use of traditional proven hydraulic actuation configurations for fault tolerance. Parker EHAs provide reduced system weight, reduced power consumption, and improved maintainability.

We have taken a leadership role with our system of EHAs, used to power all primary flight control surfaces on the F-35 Joint Strike Fighter. Jointly developed with our teammates Moog and Hamilton Sundstrand, EHAs contribute significantly to performance improvements and weight reduction at the aircraft system level.

Just to be fair and balanced here is the article that describes the serious problem they had in 2006. In it, they describe the issue as an electrical (lead shorted on lid) issue and specifically state that the EHAs were not an issue.

Oh and just to stick a fork in you, AWST did an article in August specifically addressing the heat issues and the presence of a central "massive fuel/air heat exchanger”.

[SpudmanWP]

RE:

can't climb, can't turn, can't run

Here is a press release about the some recent F-35 tests... Low and behold, it can climb and run

With more than 5,000 pounds of ordnance in its internal weapons bays, performance remained strong, with no discernable indication of the degradation sometimes experienced in current fighters because of aerodynamic drag. "The acceleration in maximum-afterburner takeoff was very quick," said F-35 Chief Test Pilot Jon Beesley. "The climb-out with full internal weapons carriage was particularly impressive to me. Very pleasant to see clean-fighter climb rates and angles while carrying a combat load."

[LowObservable]

SpudmanWP...
Interesting. So if the motors a liquid-cooled, how does the coolant get there? Have I just eliminated one critical fluid system (the hydraulics) in favor of another (actuator cooling)? Do I (Heaven forfend) have two cooling loops, one for each motor in the critical actuators? I'd rather not lose the airplane because one fluid line goes poof.
And the I-canna-alter-the-laws-of-physics question here is this: since the heat ends up in the fuel, can I get away with using all my fuel? At the end of a hot-day mission, after a diversion and a missed approach or a bolter, how much fuel must I absolutely have on board up to the second that I chop my engine? From a performance point of view, therefore, do I need a "thermal reserve" on top of my flight reserves?