It certainly wouldn't do to have to reset the main genset breaker during final to a carrier landing!
Posted on 08/25/2007 10:43:49 AM PDT by Yo-Yo
A shortage of electrical power on board the carrier variant of the F-35 Joint Strike Fighter has forced Lockheed Martin to launch a redesign of two key subsystems, even as flight tests are set to resume within the next few weeks.
Lockheed engineers discovered in laboratory tests in late 2006 that the F-35C will need 33% more power than its on-board generator can provide. The aircraft's flight-control surfaces are powered by electro-hydrostatic actuators and the electrical system has to meet the condition when all the controls demand peak power in the same instant.
The power gap was caused by flawed design estimates based on the average power demand over several seconds, says J D McFarlan, air vehicle integrated product team leader. Laboratory tests showed that instantaneous power demand could greatly exceeded the generator's 300kW capacity.
"We learned that what we call the peak power demand of all those actuators could sum up to an overall total demand greater than what the generator could provide, and for the carrier variant specifically," says McFarlan. "Luckily, we learned it in our lab."
Lockheed has contracted with Hamilton Sundstrand to increase the generator's power capacity by one-third to 400kW, he says. The US government has awarded a second contract to Pratt & Whitney to strengthen the JSF engine's gearbox to handle the extra power needed to drive the uprated generator, with the $71.5 million award covering nine systems to be completed by December 2009. The redesigned components should be the same weight and size as the previous systems, says McFarlan.
The additional work is not expected to delay flight testing of the F-35C, which should fly for the first time in the first quarter of 2009, he says, adding: "Most of the development for this is done through ground and lab testing."
Although the power shortfall is limited to the F-35C, the redesigned electrical generation system will be used in all three variants. The conventional take-off and landing F-35A and short take-off and vertical landing F-35B will be able to use the extra power to support mission system upgrades over the life of the programme, McFarlan says.
The US Government Accountability Office has warned repeatedly that the JSF programme assumes too much risk by concurrently developing and producing the aircraft.
It certainly wouldn't do to have to reset the main genset breaker during final to a carrier landing!
As long as the Pep Boys don’t suddenly appear on the HUD /obscure
the Ultimate Blue Screen of Death...
“The power gap was caused by flawed design estimates based on the average power demand over several seconds”, says J D McFarlan, air vehicle integrated product team leader. “We’ll be billing this “cost overrun” to the various governments involved in the contract, over time, and hope to be greatly rewarded for our stupidity.”
400KW? That’s enough for 200 houses! Methinks that’s just a bit on the high side. That’s 540 horsepower used JUST for electrical generation.
I’m shocked.
we are in the age of electric jets.
Just think, if GM teams with Exxon, on the HUD, they can show a tiger trying to get into the gas tank when low on fuel.
How many radars does the plane have?
I didn't work on them, but I think the F-14 had a pair of 90 KVA generators.
The Boeing 787 Dreamliner is an all electric jet. Instead of bleed air from the engines, electrical power is used to actuate the surfaces, and the brakes. What hydraulic power that is still required is generated with electric pumps.
The 787 has two engines, each with two 250 KVA generators. That’s a total of 1 MVA of power available. The APU has two 225 KVA generators.
Of course, that is overkill, designed so that the aircraft can safely fly on on generator of one engine.
> 400KW? That’s enough for 200 houses!
Well, they are sorta thinkin’ that the VTOL airframe
could substitute a directed energy weapon for the
vertical lift fan. It would need a lot of power.
2 kW per house? My wife’s hair dryer sucks that alone. Try an average of 7 kW per house.
Yeah 7K is closer. Although if you have an all-electric house and turned on all the big juice suckers at the same time (e.g. A/C, water heater, washing machine, dryer, stove and oven) you’d probably need about 30K or 40K. But that’s still 10 times less than what this one plane is using!
The more I hear about the JSF, the more I think it should be trash canned.
This comes as no surprise. Lockheed was $100 million over budget during the flyoff with the X-32 and if the government hadn’t let them off the hook for that screw up Boeing would have won the contract by default.
Just install some solar panels.
This is for a short duration power load, not average power. Control surfaces that are typically hydraulic are now electric. Should all of these control surface activate at once, combined with all of the other systems that can be operational, the power consumption would exceed the power generation capability of the generators.
I work on a system that normally draws less than 100 watts, but when active, can draw thousands of watts for a few hundred milliseconds.
How much power do you think the JSF should use?
Check with your electric utility. The average base loading is considered between 1 and 2 KW per residence. Of course there are times when more is being drawn, but the basic rule is as stated.
I was merely stating my surprize at the electrical demands of the aircraft.
The more I hear about it, the more i like it =D
look at some of the discussions at Strategypage.com , lots of the technical detail is way over my head. But I’m convince it’s a 1st rate fighter that will meet the needs of our country for a long time to come.
try this
http://www.strategypage.com/htmw/htairfo/articles/20070822.aspx
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