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#11
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"Keith Willshaw" wrote in message ... "Ian" wrote in message ... Is it still the case that the USN uses the trailing drogue (as the RAF/RN do), with the USAF using the tanker to steer the probe? If so, why the different approaches? The flying boom method has a higher transfer rate but probe and drogue can be fitted to buddy tankers. Keith Maybe a bit simplistic but couldn't they equal the transfer rates by just increasing the bore of the drogue feed pipe? It all ends up in the same fuel system (on the refuelling aircraft) so it can't be a pressure constraint? |
#12
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"Ian" wrote in message ... Maybe a bit simplistic but couldn't they equal the transfer rates by just increasing the bore of the drogue feed pipe? It all ends up in the same fuel system (on the refuelling aircraft) so it can't be a pressure constraint? That means increasing the bore of a longer length of pipe than on a flying boom. I suspect there are weight restraints at work here. Keith ----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeed.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =--- |
#13
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Keith Willshaw wrote:
"Ian" wrote in message ... Maybe a bit simplistic but couldn't they equal the transfer rates by just increasing the bore of the drogue feed pipe? It all ends up in the same fuel system (on the refuelling aircraft) so it can't be a pressure constraint? That means increasing the bore of a longer length of pipe than on a flying boom. I suspect there are weight restraints at work here. And size (hose takes up space, after all), and drag. More importantly, there are limits on the size at the other end. While large a/c can carry around a large diameter fixed probe with little effect on performance, fighters and attack a/c don't have that option. So, for instance, on their Victor tankers the RAF used Mk. 20 wing pods with smaller diameter hose/drogues (and lower flow rates) to refuel fighter/attack a/c, and a centerline Mk. 17 HDU of greater diameter hose/drogue to refuel bombers/transports (which have larger diameter probes than fighter/attack aircraft, so can accept higher transfer rates, although still not as high as a boom). A fighter just can't be carrying around such a massive piece of hardware all the time, especially if it's fixed external (there wouldn't be enough room to house it internally on a fighter, and no one seems to have tried a bomber-sized extendible probe). A boom receptacle, OTOH, is theoretically only limited in diameter by the fuel flow rates that the a/c's internal fuel piping is designed to deal with; since the flow rate in A/B is quite high, and since none of this is adding weight/drag outside the airframe, transfer rates can be much higher with little/no weight penalty on the receiver. The tanker is paying the weight/drag penalty of the boom, but it's a lot larger and can afford it. Guy |
#14
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Guy Alcala wrote:
A boom receptacle, OTOH, is theoretically only limited in diameter by the fuel flow rates that the a/c's internal fuel piping is designed to deal with; since the flow rate in A/B is quite high, and since none of this is adding weight/drag outside the airframe, transfer rates can be much higher with little/no weight penalty on the receiver. The tanker is paying the weight/drag penalty of the boom, but it's a lot larger and can afford it. And then you've got three pilots. One pilot for each aircraft and then somebody in the back of the tanker to fly the boom. -HJC |
#15
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"Henry J Cobb" wrote in message ... Guy Alcala wrote: A boom receptacle, OTOH, is theoretically only limited in diameter by the fuel flow rates that the a/c's internal fuel piping is designed to deal with; since the flow rate in A/B is quite high, and since none of this is adding weight/drag outside the airframe, transfer rates can be much higher with little/no weight penalty on the receiver. The tanker is paying the weight/drag penalty of the boom, but it's a lot larger and can afford it. And then you've got three pilots. One pilot for each aircraft and then somebody in the back of the tanker to fly the boom. The boom operator is neither trained nor paid as a pilot, so your point would be...? Brooks -HJC |
#16
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Kevin Brooks wrote:
"Henry J Cobb" wrote in message ... And then you've got three pilots. One pilot for each aircraft and then somebody in the back of the tanker to fly the boom. The boom operator is neither trained nor paid as a pilot, so your point would be...? "Fly the boom" is a common phrase in the USAF. http://www.afmc.wpafb.af.mil/HQ-AFMC...eb/0226-03.htm You need three people adjusting airfoils to make boom refueling work. That's one more person than is needed for a probe and drogue refueling. Heck, you could make an unmanned tanker for probe and drogue refueling. -HJC |
#17
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"Henry J Cobb" wrote in message ... Guy Alcala wrote: After that the USAF decided to go over completely to the boom/receptacle method, as their tankers would (presumably) always have airbases to operate from, just as their fighters and bombers would. The boom gives better transfer rates and seems to be more reliable and easier to tank from, but it does limit the types of a/c that can be tankers, and it requires a lot more money and work to convert. Will the F-35B be the first USAF aircraft since then to be built with just a probe? Clearly USAF helicopters have been built with "just a probe". Outside of the rotory wings I can't think of any USAF probe refuelers during the last 30 some years. |
#18
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On Wed, 2 Jun 2004 01:00:49 -0400, "John Keeney"
wrote: "Henry J Cobb" wrote in message ... Guy Alcala wrote: After that the USAF decided to go over completely to the boom/receptacle method, as their tankers would (presumably) always have airbases to operate from, just as their fighters and bombers would. The boom gives better transfer rates and seems to be more reliable and easier to tank from, but it does limit the types of a/c that can be tankers, and it requires a lot more money and work to convert. Will the F-35B be the first USAF aircraft since then to be built with just a probe? Clearly USAF helicopters have been built with "just a probe". Outside of the rotory wings I can't think of any USAF probe refuelers during the last 30 some years. A-7D? |
#19
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John Keeney wrote:
Clearly USAF helicopters have been built with "just a probe". Outside of the rotory wings I can't think of any USAF probe refuelers during the last 30 some years. How many helicopter capable tankers does the USAF have? Or do they have to call in the Marines? ;-) -HJC |
#20
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On Tue, 01 Jun 2004 19:17:23 -0700, Henry J Cobb wrote:
One pilot for each aircraft and then somebody in the back of the tanker to fly the boom. The boom handler is a pilot? Why? There used to be a joke about flying up dead-end canyons: don't do it unless you've learned how to fly a plane backwards. Presumably a boom operator could do just that. all the best -- Dan Ford email: (put Cubdriver in subject line) The Warbird's Forum www.warbirdforum.com The Piper Cub Forum www.pipercubforum.com |
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