Yahoo article: America's F-105 Thunderchief Fighter-Bomber: The F-35 of the Vietnam War? | The National Interest Blog
Love the F105... Good vid shot in 1966 on it.... [ame]http://www.youtube.com/watch?v=Hun_uUuufOs[/ame]
Yup, and Boeing is going to miss its August 2017 deadline for KC-46 deliveries, so they will continue in use for a while. F-105s also used KC-97 tankers. I got to fly pathfinder with an F-111D for four F-105Ds out of Carswell in the 70s. They only had Doppler nav systems. Mission was low level attack in the Nellis ranges. We asked them how fast and they said 540 KGS (621 mph). During the debrief they said we should have asked for 570 KGS (656 mph). 105s were about the only thing almost as fast as an F-111 at low altitude. Incidentally, they did pop-ups to dive, while we dropped our ordnance ordnance level at 200' AGL. We all hit a tanker going in, and the 105s hit one exiting, too. We did not need it to get back to Cannon.
Is that for the boom issues? I haven't been following it very closely I would be curious how an early 135 might stack up against a 46.... I'm sure the 135 must have had some teething problems which were probably dealt with in a much simpler manner than they are this days.
The 767 is a rock solid and tough airplane as well as a good performer (although a bit slow at cruise by today's standards). UPS, DHL and Fedex like the 'F' models and some are still being delivered. (information from Public Domain) Without going into too much detail, the KC-46, like anything designed by "committee" (the Government with continuously changing requirements), boom and drogue operations and every combination of using one or both can be problematic... The fueling and distribution system is 10 times more complicated than the KC135. The boom operator doesn't even sit in the tail. (Up front with 3D display). The technology is new and it will be "buggy" at first. Once solved this should be a good airplane.
The designed by committee comment is right on. The Air Force has caused never ending problems in the configuring the KC-46. They have changed elex equipment when wiring had already been installed so it had to be ripped out and changed. Then they changed the equipment again after the new bundles had been installed. Time and Time again! Many other problems have disrupted the flow of the program and it hasn't been Boeing! The 767 is a great airplane and it will perform well if the Air Force ever gets it's act together. New technology, as Spasso indicated, always has bugs so we have to itch accordingly. I worked on the KC-135 program and there weren't many glitches from the start but the game is much more complex now. Boeing is not to blame.
The issue is a boom problem with only one aircraft. The simultaneous boom and drogue capability is not part of the initial 18 deliveries that will be delayed. Hard to directly compare the 135 and 46 since the 767 airframe can carry so much more fuel and is so much more modern.
But what I have read specifically points out the issue with boom and drogue use and that it did affect the early deliveries. In fact, the early deliveries won't have full functionality, boom only if I recall. The source could have been inaccurate in that respect and maybe my interpretation but I have pretty good recall on the stats. I also recall that there was an issue with using the boom with C-17. (or was it C-5?)
Boeing says it has figured out how to fix the refueling boom on its brand-new Air Force KC-46 tanker. Next month, the company plans to test a new piece of hardware meant to remedy a design problem that has prevented the tanker from refueling C-17 cargo planes. “We will be flying the aircraft [with the modified boom] in the July timeframe,” Leanne Caret, president and CEO of Boeing’s defense unit, said Wednesday at the Deutsche Bank Global Industrials and Materials Summit. The boom, essentially a pipe that descends from the tail of the tanker to pass fuel to the receiving aircraft, telescopes in and out as tanker and receiver fly about a dozen feet apart. While the KC-46 has successfully refueled small F-16 fighter jets, the larger C-17 places “higher than expected” pressures, called axial loads, on the boom, said Caroline Hutcheson, a Boeing spokeswoman. “This control system must maintain enough contact pressure to keep the refueling nozzle connected, but not too much pressure as to place excessive force on the tanker or receiver aircraft structure,” Hutcheson said. The company had hoped to correct the boom problem with a software update. That fix “worked to a degree in flight test, [but] it wasn’t as robust as we wanted,” Dennis Muilenburg, Boeing chairman, president and CEO, said June 2 at the Bernstein Strategic Decisions Conference. Instead, Boeing is going with a “hardware solution” that is “more robust for the long run,” he said. The company will install a “hydraulic relief valve system” that is about the size of a paperback book, Hutcheson said. “Two bypass valves are inserted into the hydraulic system so that if loads build up on the boom, the valves open to relieve the pressure,” she said. The system is similar to equipment used on the booms of the Air Force KC-10 and KC-767 tankers, which are flown by the Japanese and Italian air forces. “The Air Force is comfortable with Boeing’s hardware approach, given it is similar to how axial load relief is accomplished on our legacy KC-10 tanker,” said Daryl Mayer, an Air Force spokesman for the KC-46 program at Wright-Patterson Air Force Base in Ohio. “We look forward to reviewing the details of Boeing’s design of the hydraulic relief valve on the KC-46 to ensure it will properly alleviate axial loads in flight.” The boom problem has prompted the service to delay awarding a contract for more aircraft. Certification and qualification issues will cause Boeing to miss a contractual deadline to deliver 18 planes to the Air Force by August 2017. Muilenburg said the company would still build 18 tankers by August 2017, but those planes “won’t be completely certified.” Air Force officials said all 18 planes would not be delivered until January 2018. What penalties will Boeing face for missing the delivery deadline? “As with any contract schedule breach, the Air Force will seek consideration commensurate with the impact of the breach,” said Maj. Robert Leese, a service spokesman at the Pentagon. The Air Force will “secure consideration from Boeing” as it now resets the project’s schedule. The Air Force’s contract with Boeing does not list specific penalties for missing schedule deadlines, Leese said. Boeing executives say they are evaluating the financial impact the boom fix will have on the tanker project, whose various developmental problems have already cost the company $1.5 billion. Under the terms of the contract, Boeing, not the Pentagon, must pay for cost overruns. The firm will likely need to pony up more money to fix the boom. In a recent note to investors, defense consultant Jim McAleese, who runs Virginia-based McAleese and Associates, said to “expect potential for additional ... KC-46 charge” when Boeing reports second-quarter earnings. “We'll work through the local financial impacts of that and cash timing of that, part of our normal financial process,” Muilenburg said. “So, that analysis is underway.” Boeing has proposed several types of refueling booms to the Air Force over the years. In August 2007, it touted the “fifth-generation boom” on its Japanese and Italian KC-767 tankers. Later that year, Boeing cited the “sixth-generation boom” it was proposing for the U.S. Air Force. The Air Force instead chose Northrop Grumman and Airbus to build a new tanker based on the A330 jetliner in February 2008, but that award was overturned after Boeing contested the contract. When Pentagon reopened the tanker contest in 2010, Boeing touted “a new-generation fly-by-wire boom.” And when the Air Force chose Boeing’s KC-46 proposal, the firm said its tanker “features an advanced KC-10 boom with an expanded refueling envelope, increased fuel offload rate and fly-by-wire control system.” Boeing considers the KC-46 a “franchise program” worth upwards of $80 billion. While the Air Force plans to buy 179 KC-46 tankers for about $30 billion, Boeing believes the military could ultimately buy as many as 400 planes to replace all of its KC-135s. In addition to the initial sale of each plane, the company expects to make billions of dollars from maintenance and logistics work over the tankers’ expected decades of service. Caret said she works on the KC-46 project on a daily basis. Even though she’s based in St. Louis, Caret is routinely in Seattle, where Boeing builds the plane, to keep an eye on the project
The KC-10 had two fuel pumps that gave more fuel flow than the KC-135's single pump. Some aircraft, though, could not accept the increased fuel flow of the KC-10's dual pumps, so only one pump could be used. One pump has less flow than a KC-135, naturally. Hopefully, they have variable flow rate pumps on the KC-46 to match whatever rate is needed. KC-10s deployed us and our F-111Fs to Saudi Arabia in August 1990, and the good thing was they could also carry our maintenance and support personnel, along with extra aircrew members and spare F-111F parts, at the same time. The KC-46 should be able to do the same thing even better.
Actually the KC-135 has four hydraulically powered pumps that pump the fuel for offloading fuel to a receiver aircraft. Depending on what kind of plane you are giving gas to you use anywhere from one to four pumps. These pumps are much more powerful than electrically powered pumps.
Jim- I got the details on that story wrong, but I remember the flow rate to some aircraft was higher on the KC-135, and on others, higher on the KC-10 because they could not use full flow. Turns out the KC-135 has 4 pumps, like you said, and the KC-10 6 pumps, and each individual aircraft had a different max refueling rate. For the A-10 max rate was around 2500 ppm from a KC-135 and 3000 ppm from the KC-10. Have to look in my -1 and see what it was for the F-111F, but 5000 ppm seems about right. We carried a lot of external fuel, ~34,000 lbs of JP-8, so needed a high transfer rate.
They are powered by the airplane hydraulic systems. So there are four engines and each one has a hydraulic pump and the system is split between the left and right sides. There are two hydraulicly powered fuel pumps that can offload gas in the foward body tank and two in the aft body tank. In each tank one of the pumps are driven by the left system while the other is driven by the right system.
Yes, there is a wide difference in offload speeds depending on aircraft type, and also sometimes between aircraft of the same type. There is a prescribed number of pumps for each aircraft type, but offload rates would vary between planes. The slowest was always the navy jets while some of the heavies would be close to 6000/min.
Jim- I meant to say internal fuel, not external. Good news that the new boom software seems to have cured the problem. Not sure if there was a hardware fix, too.
