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When I read lines such as: >"But take a look at the F-35’s engine nozzle. It’s round. Highly stealthy planes such as America’s B-2 bomber and F-22 fighter both

by pcrh 11y ago

When I read lines such as: >"But take a look at the F-35’s engine nozzle. It’s round. Highly stealthy planes such as America’s B-2 bomber and F-22 fighter both boast flat engine nozzles " I really doubt the credibility of the author; as if engineers would overlook such a basic factor if it was that crucial.

angersock 11y ago
It's not that they overlooked it as such--it's that, at different points in the plane's design, requirements changed. The original powerplant design was probably settled on before the stealth requirements were brought up.
- engi_nerd 11y ago
  That's not the case at all. The aircraft has always been intended to be stealthy. The X-35 prototypes used F119 engines from the F-22 program (also a stealth aircraft). The F135 engine is a follow-on development with the F119 as a starting point.
bdavisx 11y ago
I doubt the engineers would overlook anything like that. It's more like: Engineer: "We can't get the engine to work with the current airframe design if we use stealthy engine nozzles. It's going to require a significant re-design." Manager: "Will it work with old style round nozzles? Then use those."
bkohlmann 11y ago
The JSF C-variant (carrier based) had a hook that didn't work last year...they finally rectified it. When it comes to the F-35, there are a lot of engineering items that have been overlooked that are mindboggling.
- engi_nerd 11y ago
  Your information isn't quite correct. Initial trials of the arresting system were conducted in 2011 at Lakehurst. The hook had several deficiencies, in part because a wire dynamics model provided by the government for the team to design against had faulty assumptions. Several components were redesigned and re-tested. During the first sea trials of the system in October 2014, two F-35C aircraft deployed to the USS Nimitz where the trials were highly successful: http://www.navytimes.com/story/military/tech/2014/11/15/f-35c-navy-carrier-nimitz-sea-trials-trap/19019879/ http://www.navytimes.com/story/military/tech/2014/11/15/f-35... "The F-35C test pilots have made approximately 100 traps on the Nimitz, and the three wire was caught so many times that the metal cable had to be replaced. The one wire, the cable furthest aft on the flight deck, hadn't been used at all, Wilson said." What other engineering items have been overlooked that you believe are mindboggling?
baddox 11y ago
It doesn't have to be a mistake or something overlooked. Consider the possibility that funneling money from the US government to defense contractors is the primary goal, and that the shape of the engine nozzles isn't particularly relevant to this goal.
trhway 11y ago
>I really doubt the credibility of the author; as if engineers would overlook such a basic factor if it was that crucial. i vaguely remember reading something/somewhere that less stealthy round instead of stealthier flat was a cost cutting decision.
GVIrish 11y ago
> I really doubt the credibility of the author; as if engineers would overlook such a basic factor if it was that crucial. The problem is that the F-35 had requirements that fundamentally conflict with each other. It had to have a STOVL configuration, which probably dictated the nozzle design. But it also had to be 'stealthy', so the nozzle design and the wide fuselage needed for the STOVL requirement, negatively affected the stealth requirement. So much so that the stealth rating of the F-35 was downgraded. It was also supposed to be more maneuverable than the F-16, but the other requirements resulted in aerodynamic performance that was less than what was originally planned. So much so that it lost a mock dogfight against a F-16. Granted that test is not the end of the story but it's not a good sign. Then there's the fact that the military and Congress inexplicably decided that they'd throw the normal testing and validation phase out the window in favor of 'concurrency' where they're putting the aircraft into production before testing is done. This has the dual downsides of ensuring expensive retrofits when problems are identified but it commits the government even more deeply to a weapons system that may ultimately never perform as billed.
nether 11y ago
The round nozzle is a tradeoff for weight. It's a single powerplant aircraft so the IR signature was probably considered satisfactory versus twin rectangular nozzles. The T-50 (prototype aircraft that Russia can't afford to further develop) and the Su-35 he brought up for comparison use two round nozzles, but he somehow neglected to factor that into his comparison. The rest of the 20 different systems he compares the F-35 to either would bankrupt Russia if they were to ever put them into mass production, or the comparisons themselves isolate one feature of the F-35 against some long-shot (probably exaggerated) capability of such-and-such Russian system. I could say that the F-35 could use its low-observable phased array radar to detect the Su-35 from twice the distance of the latter without triggering the enemy's RWR, fire off an AIM-120 and turn around before the Su-35 detected it. And pretty much every shortcoming for the F-35 (sensors, supercruise, stealth) he brought up is far worse for the F-16, A-10, and AV-8B which the F-35 is intended to replace.
- engi_nerd 11y ago
  > The T-50 (prototype aircraft that Russia can't afford to further develop) and the Su-35 he brought up for comparison use two round nozzles They also have two engines.
- icanhackit 11y ago
  the F-35 could use its low-observable phased array radar to detect the Su-35 from twice the distance of the latter without triggering the enemy's RWR, fire off an AIM-120 and turn around before the Su-35 detected it Right, when people complain about the F-35, for all its shortcomings, they look at it as though it should be a "faster horse" (it's an apocryphal anecdote but makes a good point) rather than a whole new weapons platform. The USAF clearly wants something that doesn't engage in close combat, so it's about superior sensors and long range/precision air-to-air and air-to-ground weaponry. I think the biggest shortfall of the F-35 though is its close air support capabilities. The USAF just want to have the target marked by ground forces and for the F-35 to drop small precision munitions on the area, but a big part of CAS is psychological - when you hear that 30mm cannon burp and the A-10's engines loitering in the background, you feel safe while your enemy is terrified. Plus a loitering A-10 is more useful than an F-35 with an ephemeral presence. Solution: give the Army the ability to provide CAS so they can purchase the A-10's from the USAF. The USAF can play with their fancy spaceships while the Army can have its flying gun.
engi_nerd 11y ago
http://www.f-16.net/f-16_versions_article20.html http://www.f-16.net/f-16_versions_article20.html Oh, they didn't overlook it. The mere fact that he assumes that only flat nozzles are stealthy tells me that the author has not done his research. From my reading of this article, the author accepts the absolute most pessimistic estimates of the F-35 and also accepts the most optimistic estimates and statements of the capabilities of other aircraft and radar systems, without questioning these estimates. For example, take this line: "Tehran insists its Ghadir radar can spot jets more than 300 miles away." Tehran also insisted that their Qahar 313 is real, when it's a laughable fake: http://www.thewire.com/global/2013/02/iran-new-stealth-fighter-jet-fake/61781/ http://www.thewire.com/global/2013/02/iran-new-stealth-fight.... Now, just because the Qahar 313 is likely fake, that doesn't mean their Ghadir radar can't spot aircraft at 300+ miles. But shouldn't the Qahar fake make a "security analyst" like the author take a closer look at subsequent claims by the same government?

by pcrh 11y ago

angersock 11y ago

It's not that they overlooked it as such--it's that, at different points in the plane's design, requirements changed. The original powerplant design was probably settled on before the stealth requirements were brought up.

engi_nerd 11y ago
That's not the case at all. The aircraft has always been intended to be stealthy. The X-35 prototypes used F119 engines from the F-22 program (also a stealth aircraft). The F135 engine is a follow-on development with the F119 as a starting point.

bdavisx 11y ago

I doubt the engineers would overlook anything like that. It's more like: Engineer: "We can't get the engine to work with the current airframe design if we use stealthy engine nozzles. It's going to require a significant re-design." Manager: "Will it work with old style round nozzles? Then use those."

bkohlmann 11y ago

The JSF C-variant (carrier based) had a hook that didn't work last year...they finally rectified it. When it comes to the F-35, there are a lot of engineering items that have been overlooked that are mindboggling.

engi_nerd 11y ago
Your information isn't quite correct. Initial trials of the arresting system were conducted in 2011 at Lakehurst. The hook had several deficiencies, in part because a wire dynamics model provided by the government for the team to design against had faulty assumptions. Several components were redesigned and re-tested. During the first sea trials of the system in October 2014, two F-35C aircraft deployed to the USS Nimitz where the trials were highly successful: http://www.navytimes.com/story/military/tech/2014/11/15/f-35c-navy-carrier-nimitz-sea-trials-trap/19019879/ http://www.navytimes.com/story/military/tech/2014/11/15/f-35... "The F-35C test pilots have made approximately 100 traps on the Nimitz, and the three wire was caught so many times that the metal cable had to be replaced. The one wire, the cable furthest aft on the flight deck, hadn't been used at all, Wilson said." What other engineering items have been overlooked that you believe are mindboggling?

baddox 11y ago

It doesn't have to be a mistake or something overlooked. Consider the possibility that funneling money from the US government to defense contractors is the primary goal, and that the shape of the engine nozzles isn't particularly relevant to this goal.

trhway 11y ago

>I really doubt the credibility of the author; as if engineers would overlook such a basic factor if it was that crucial. i vaguely remember reading something/somewhere that less stealthy round instead of stealthier flat was a cost cutting decision.

GVIrish 11y ago

> I really doubt the credibility of the author; as if engineers would overlook such a basic factor if it was that crucial. The problem is that the F-35 had requirements that fundamentally conflict with each other. It had to have a STOVL configuration, which probably dictated the nozzle design. But it also had to be 'stealthy', so the nozzle design and the wide fuselage needed for the STOVL requirement, negatively affected the stealth requirement. So much so that the stealth rating of the F-35 was downgraded. It was also supposed to be more maneuverable than the F-16, but the other requirements resulted in aerodynamic performance that was less than what was originally planned. So much so that it lost a mock dogfight against a F-16. Granted that test is not the end of the story but it's not a good sign. Then there's the fact that the military and Congress inexplicably decided that they'd throw the normal testing and validation phase out the window in favor of 'concurrency' where they're putting the aircraft into production before testing is done. This has the dual downsides of ensuring expensive retrofits when problems are identified but it commits the government even more deeply to a weapons system that may ultimately never perform as billed.

nether 11y ago

The round nozzle is a tradeoff for weight. It's a single powerplant aircraft so the IR signature was probably considered satisfactory versus twin rectangular nozzles. The T-50 (prototype aircraft that Russia can't afford to further develop) and the Su-35 he brought up for comparison use two round nozzles, but he somehow neglected to factor that into his comparison. The rest of the 20 different systems he compares the F-35 to either would bankrupt Russia if they were to ever put them into mass production, or the comparisons themselves isolate one feature of the F-35 against some long-shot (probably exaggerated) capability of such-and-such Russian system. I could say that the F-35 could use its low-observable phased array radar to detect the Su-35 from twice the distance of the latter without triggering the enemy's RWR, fire off an AIM-120 and turn around before the Su-35 detected it. And pretty much every shortcoming for the F-35 (sensors, supercruise, stealth) he brought up is far worse for the F-16, A-10, and AV-8B which the F-35 is intended to replace.

engi_nerd 11y ago
> The T-50 (prototype aircraft that Russia can't afford to further develop) and the Su-35 he brought up for comparison use two round nozzles They also have two engines.
icanhackit 11y ago
the F-35 could use its low-observable phased array radar to detect the Su-35 from twice the distance of the latter without triggering the enemy's RWR, fire off an AIM-120 and turn around before the Su-35 detected it Right, when people complain about the F-35, for all its shortcomings, they look at it as though it should be a "faster horse" (it's an apocryphal anecdote but makes a good point) rather than a whole new weapons platform. The USAF clearly wants something that doesn't engage in close combat, so it's about superior sensors and long range/precision air-to-air and air-to-ground weaponry. I think the biggest shortfall of the F-35 though is its close air support capabilities. The USAF just want to have the target marked by ground forces and for the F-35 to drop small precision munitions on the area, but a big part of CAS is psychological - when you hear that 30mm cannon burp and the A-10's engines loitering in the background, you feel safe while your enemy is terrified. Plus a loitering A-10 is more useful than an F-35 with an ephemeral presence. Solution: give the Army the ability to provide CAS so they can purchase the A-10's from the USAF. The USAF can play with their fancy spaceships while the Army can have its flying gun.

engi_nerd 11y ago

http://www.f-16.net/f-16_versions_article20.html http://www.f-16.net/f-16_versions_article20.html Oh, they didn't overlook it. The mere fact that he assumes that only flat nozzles are stealthy tells me that the author has not done his research. From my reading of this article, the author accepts the absolute most pessimistic estimates of the F-35 and also accepts the most optimistic estimates and statements of the capabilities of other aircraft and radar systems, without questioning these estimates. For example, take this line: "Tehran insists its Ghadir radar can spot jets more than 300 miles away." Tehran also insisted that their Qahar 313 is real, when it's a laughable fake: http://www.thewire.com/global/2013/02/iran-new-stealth-fighter-jet-fake/61781/ http://www.thewire.com/global/2013/02/iran-new-stealth-fight.... Now, just because the Qahar 313 is likely fake, that doesn't mean their Ghadir radar can't spot aircraft at 300+ miles. But shouldn't the Qahar fake make a "security analyst" like the author take a closer look at subsequent claims by the same government?