Panetta To Lift F-35B Probation at Pax River

[1st503rdsgt]

The news is always mixed, but this is a step in the right direction.

http://defense.aol.com/2012/01/19/panet ... pax-river/

[F16VIPER]

I would had thought that the issue of the f-35b not having any provision for growth, or accepting additional weight, would be a pretty big issue and a deal breaker. From what I have been reading the design of the aircraft is pretty compromised already.

[quicksilver]

With a similar load, the F-35B is faster, accelerates much better (both subsonic and transonic) and has more range than a Super Hornet that is starting up on the ramp with 3500# more fuel. It has the same sensor capabilities as its F-35A and C (CTOL and CV) counterparts and has more basing options than either -- both ashore and afloat. Compromised design?

In spite of the most intense (and often deliberate and orchestrated) bashing in the history of aircraft development programs (save V-22), speculation is that the F-35B may be removed from 'probation' tomorrow by the current Secretary of Defense.

Compromised design? You may wanna reconsider what you typically read -- or at least what you choose to believe.

[F16VIPER]

Compromised design because of the design changes implemented to make the F-35B work and because it appears a "Jenny Craig" weight reduction exercise has already been carried out leaving no room to manoeuvre if weight creeps up. As far as I understand and in simple terms, with the -35B, if weight is gained, it has to be shaved off the plane itself. Where is that weight reduction going to come from.

[quicksilver]

Hmmm, "...if weight is gained, it has to be shaved off the plane itself." Holy crap -- make sure the test pilots eat a light breakfast.

Are you for real, or just drinking cheap wine?

Do you understand VLBB and how it is calculated for the purpose of determining performance relative to the KPP?

[F16VIPER]

i generally drink mid range cabernet souvignons or pinot noirs, never cask wine.
Well the weight it is going the pilots will need to eat astronaut food before flying the plane. No steak.
Read this:
http://www.f-16.net/index.php?name=PNph ... c&p=163550
and this:
http://www.f-16.net/f-16_forum_viewtopi ... rt-15.html
Salud!

[battleshipagincourt]

Hmmm, "...if weight is gained, it has to be shaved off the plane itself." Holy crap -- make sure the test pilots eat a light breakfast.

Are you for real, or just drinking cheap wine?

That's not going to help matters. The F-35B was a bad idea because the most significant challenge wasn't optimizing the aircraft to perform its mission... it's landing. The reason the F-35A is the best of the three variants is because it makes the fewest design compromises. Consider a simple thing like adding a 300 Ib module such as the EOTS to improve the aircraft's fighting capabilities... that's a reasonable addition to the F-35A or the F-35C.

Add such a module to the F-35B and now you're burdened with balancing the plane again to compensate for another 300 Ibs of dead weight to the front of the aircraft. Now you're forced either to add another 300 Ibs to the back of the plane, or remove 300 Ibs somewhere else. All the while you're designing the whole aircraft around the STOVL system, you've still got to maintain the stealth outline and meet your target performance goals.

I seriously don't think anyone here truly understands the burden the STOVL puts on designing the rest of the aircraft. The 'F-35B diet' hasn't been as beneficial to the other models' capabilities as people seem to think. The weight reduction measures weren't optimized for aircraft performance, but for making the ****** thing meet the STOVL requirements.

Many of the recent structural fatigue failures in all the F-35's can be traced to the weight-reduction measures they made for the F-35B.

[spazsinbad]

bsac, where have you been?

[alloycowboy]

Everyone is forgetting one little bitty fact. Just like aircraft weight can go up, so can aircraft thrust.

@Battleship...... How haven't the F-35A & F-35C model benefited from the F-35B's 3000 pound weight reduction. Even if they have a little weight back in to beef up some of the structural hotspots the F-35A and F-35C are still way better off because of the SWAT program.

[beepa]

[quote="alloycowboy"]Everyone is forgetting one little bitty fact. Just like aircraft weight can go up, so can aircraft thrust.

Ok, as we know, increasing thrust causes lower engine life, more maint, more fuel etc etc...but is still possible on the F35 a/c. The F35b has gearboxes, shaft, clutch, fan and rotating nozzle... so the question is..can all these parts handle more thrust...and.. is the gain in thrust in the F135 from internal mods or afterburner mods or a combo of the two? ( i.e. during vertical landing afterburner can't be used)

[spazsinbad]

beepa, here is an answer in part with perhaps more to follow...

F-35B starts critical tests in comeback attempt Stephen Trimble 05 Oct 2011

http://www.flightglobal.com/news/articl ... pt-362941/

“...The cracked bulkhead has been patched up and redesigned and three of the five glitches in the propulsion system are already permanently fixed. Of the remaining two issues, one fix is scheduled to be approved in December, and the last problem should be resolved in February 2012, Robling added. Although the F-35 was grounded for 16 days in August, the electrical system at the root of the problem is common to all three variants.

Meanwhile, programme officials also appear to have resolved a 90.7kg performance shortfall in the vertical lift bring-back weight of the F-35B in hover while returning to a ship. Engine manufacturer Pratt & Whitney has confirmed the solution includes raising the output of the propulsion system by about 100lb-thrust (0.4kN)...."
______________________________

Pratt Advances On F135 Stovl Boost Plan – Apr 6, 2011 By Guy Norris

http://www.aviationweek.com/aw/generic/ ... line=Pratt Advances On F135 Stovl Boost Plan
-
“Pratt & Whitney has updated progress on a four-point plan to help Lockheed Martin correct issues with the F-35B short take-off and vertical landing (Stovl) variant, development of which has been placed "on probation" by Pentagon leadership....

...Describing additional details of the company's four-point plan for the F135-600 Stovl engine variant, Boley says first "we have to understand what role we have in any additional vertical lift bring back (VLBB). We can provide more thrust if that's desired." The overall VLBB requirement, which refers to returning for a vertical landing with an unused weapons load corresponding to two 1,000-lb. JDAMs and two Amraams, is around 3,000 lb.

Lockheed Martin "is not asking for more thrust, but if we did provide it, it will be 100 lb., which is easily accommodated," Boley says. The thrust delta, achieved through a scheduling change in the full authority digital engine control, is so small compared to the engine's overall max hover thrust capability that it could "almost be a production variability."

Thrust increase would necessarily have to be spread evenly throughout the system, which, in hover mode, diverts around 16,000 lb. through the engine's main nozzle, 20,000 lb. via the lift fan and an estimated 4,000 lb. through the roll posts. Pratt formerly indicated the main nozzle delivers 15,700 lb., the lift fan 20,000 lb. and roll posts some 3,700 lb., combining for a total of 39,400 lb. thrust. However, the company confirms total max hover thrust is now "greater" than 40,000 lb. In conventional up-and-away mode, the F135 is rated at 43,000 lb. thrust. Lockheed's "stack up" of items that will increase VLBB is mainly being tackled through further trimming of unspecified empty weight and other non-engine-related changes, Boley says...."

[1st503rdsgt]

I would had thought that the issue of the f-35b not having any provision for growth, or accepting additional weight, would be a pretty big issue and a deal breaker. From what I have been reading the design of the aircraft is pretty compromised already.

Does anyone know what the AV-8's "provision for growth" was when it entered service? Seems to me that STOVL fighters will always be close to the margins (or "compromised" to those prone to panic), and it's apparently something we've lived with before.

[F16VIPER]

I would like to go back to my original comment. The design of the F-35B is compromised.
Please read this

http://defense.aol.com/2012/01/13/f-35b ... sters-say/

One other important detail surfaces in the report, the weight of the Marines F-35B. While the issue of weight is not new for the STOVL aircraft, the report says the weight margin is not huge, roughly 235 pounds as of November. "managing weight growth with such tight margins for the balance of SDD will be a significant challenge, especially with over 70 percent of the scheduled F-35B flight sciences test flights remaining to be accomplished in the next 60 months." The current F-35B weight allows for .36 percent weight growth per year, the report notes, compared to the F-18 E/F's gain of .69 percent per year for the first 42 months after first flight.

[1st503rdsgt]

I would like to go back to my original comment. The design of the F-35B is compromised.
Please read this

http://defense.aol.com/2012/01/13/f-35b ... sters-say/

One other important detail surfaces in the report, the weight of the Marines F-35B. While the issue of weight is not new for the STOVL aircraft, the report says the weight margin is not huge, roughly 235 pounds as of November. "managing weight growth with such tight margins for the balance of SDD will be a significant challenge, especially with over 70 percent of the scheduled F-35B flight sciences test flights remaining to be accomplished in the next 60 months." The current F-35B weight allows for .36 percent weight growth per year, the report notes, compared to the F-18 E/F's gain of .69 percent per year for the first 42 months after first flight.

Again, I'm gonna need a STOVL point of reference (like the AV-8's initial weight margin) before I start to worry.

[alloycowboy]

@F16viper....... There are always ways to take weight out of an airplane, the question is how much will cost?