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#41
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"Kevin Brooks" wrote in message ... "Guy Alcala" wrote in message . .. Kevin Brooks wrote: "Guy Alcala" wrote in message . .. Kevin Brooks wrote: "Guy Alcala" wrote in message .. . Sorry for the delayed reply -- it's been a busy week. Kevin Brooks wrote: snip corrosion lead-in You are forgetting the corrosion problems with the E models--corrosion tends to reduce fatigue life, too, IIRC from my long-ago materials science classes... Corrosion is an issue with any a/c -- certainly the KC-135Rs as well, which (after all) were 135As before, just as the Es were. It sounds to me like the only way you are going to get that long a life from the E's would be if you also replaced some structural components (meaning you are going even further than the old R model mods, IIRC). Why is corrosion and fatigue on the Es supposedly so much more serious than the Rs, when they all started out as 135As? I'd assume they are both going to exhibit corrosion problems, but didn't the R's go through a significant IRAN as part of their upgrade? Not that I can find, but that's not definitive. Boeing replaced the lower wing skinsof 746 C/KC-135s, but that seems to have been applied to all models in service. All I can figure is that the old nacelles and struts (from 707s) may be causing the difference, which would go away if they were upgraded to Rs (which get new struts and nacelles as well as engines). The USAF, per those comments from the three-star last year, seems most concerned with the E's. See above, or possibly just because the Es were less effective than the Rs, so sure, say they're falling apart because of corrosion so we can buy new a/c. You've got to come up with some justification. No, I don't have to. A serving USAF LTG made the statements quoted to you--the best you have offered in response is that the DSB says they can control the problem--if enough money is committed to maintenance on a yearly basis. Duh. Doesn't it sound a bit odd to hear a response that says, "It is not a problem--if we dump enough money into it annually throughout the remaining service life..."? That sounds like the very definition of a "problem" to me. Ooops--late night! Hit the send key a bit early... snip Wait a second--spend *more* money on trying to upgrade E's, while doing *another* study to determine if/when/how we replace the E's? What do you mean, _trying_ to upgrade the Es? We know perfectly well how to upgrade them -we've got 400+ prototypes in service, after all, with the R&D all paid for. No, no, no--that was not what I meant. My point is that at this point tossing *more* money into the upgrade of the E models seems a bit shortsighted, when that same money (along with the savings accrued from cheaper operating costs) could go towards purchasing new-build airframes. We did not have that option (or the money to make it happen) available back when the original R program started--we do now. Actually, we don't have the money at the moment, which is why the whole lease thing was suggested. But look at it another way -- might it make more sense to upgrade some/all Es to Rs at far lower cost than than buying 767s, while we perhaps decide to skip the 767 generation entirely and buy either a 7E7 tanker, or even a BWB one around 2015 or so, if the latter a/c is more suitable in the long term? Considering the difference in cost between upgrading an E to a Pacer Crag R vs. buying new KC-767s, it's going to take a considerable time (a couple of decades, I imagine) for the O&M cost advantage of the latter to overcome purchase cost advantageof the former, assuming that it ever does (at least one source claims that it won't). Pardon me for not inserting "or leasing" after "purchasing". Last I heard, Boeing has gotten very quiet about the whole BWB concept, so I am not sure how much confidence you can put into it. And again, after spending some $3.6 billion to upgrade the remaining E's (which still have that corrosion "problem", albeit one that the DSB contends we can discount--if we are willing to dump enough money into future maintenance...), how sure are you that you will be able to get funding for *another* major tanker program in short order? That sounds like a fine...bureaucratic solution? Even the GAO was saying in the 1990's that the USAF needed to get off its duff and start planning the replacement of the KC-135E fleet. Sure. It didn't say what to replace them with. Nope. The USAF has said what they want to replace them with--you have no trust in the USAF? The USAF said what it wanted to replace them with in 2001, when they had no other US choice, and still haven't justified the _need_ to replace them now, vs. other options. The assumptions have changed, as has the situation. Guy, for gosh sakes--they *still* have no other domestic choice beside the 767! Your 7E7 has not even been *designed* yet, much less is it ready to take to the skies in tanker mode. Studies are great--unfortunately, they have a tendancy of becoming an ends-unto-themselves. We have a good proposal that the USAF has supported--it puts new airframes into the mission much more quickly than if we follow the "usual" method of purchasing new aircraft (of course, you could use the F/A-22 or F-35 model...which would mean if we started that new study right now, we might plan on seeing some new tankers around what...2015 at best?), and it takes advantage of an existing excess production capability/inventory at the only US company currently building aircraft of that class--sounds like a good plan to me. Who says we need new airframes _right_ now? As we both agree, buying more pods and converting more Rs to carry them is the best solution in the short term to the navy/Allies problem, while converting Es to Rs _may_ be the best solution for increasing our tanker force in a hurry. Or it may not be, butsince the USAF never did an Analysis of Alternatives (AoA), we don't know. Upgrading to R's does not do a great deal towards "increasing our tanker force"--it instead is more of a "spend some money now to reduce O&M costs in the long run, and keep the force from being *reduced* as E models break". Of course, the 767 option does ptretty much the same thing--albeit with an even greater reduction in operating costs, and a significantly better possibility of future upgrades (at what point does it become impractical to keep trying to modernize a 43 year old airframe?). You'd better ask Bufdrvr (or the Air Force) about that one;-) However, I disagree with your premise - upgrading Es to Rs does indeed increase our tanker force, both by improving MC rates, and by increasing offload and reducing runway length requirements, just as the KC-767 would. The E is restricted by lack of thrust in the amount of fuel it can lift off many runways, compared to the R or a 767 (Boeing claims the 767 can lift the same fuel load from a 4,000 foot shorter runway). The A model was even worse, of course, being essentially useless during DS from most runways in the middle east. Hot and/or high has become pretty typical for us, so tankers that have trouble operating from such fields are essentially operationally useless (which is what the USAF general claiming that we needed the 767 to replace the Es said). OK, you win. I vote we keep the KC-135 flying for another forty years--when the wings start shedding from them in flight, maybe we can discuss replacing them? Of course, you will guarantee that the ever increasing O&M costs, to include that extra money required to solve that "non-problem" corrosion situation, will be forthcoming every year, and that we can continue to upgrade them as required throughout that period... Nah, just kidding. This has been interesting, and informative; I hate to admit it ( :-) ), but I have learned a few things in this thread--though nothing that convinces me that either (a) we should not continue with procurement of the 767 tanker, or (b) there is something critically wrong with procuring the first 40 767's without multi-point capability up-front. And BTW--I don't find the assertion that we could keep the E's flying "as is" very convincing--ISTR there are real concerns over the availability of engines and related parts for the existing powerplants, so if you wanna go the "keep the E's" route you are realistically going to *have* to upgrade them. Thanks for the info, and I appreciate the discourse. Brooks snip what has become one of our more long-winded discussions |
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Guy Alcala wrote in message ...
sameolesid wrote: snip Just had a look at AFPAM 10-1403, which among other things lists military and CRAF a/c types for various roles and missions. Fuel burn for generic planning purposes of a KC-135R is listed as 10,921 lbs./hr. A CRAF B-767 (sub-type unstated) is listed as 10,552 lb./hr. A tanker version would have more drag (boom, receptacle and various fairings, never mind wing pods), so fuel burn of the two types appears to be essentially equal. Real world fuel burn for a 767-200 planned for a transatlantic this afternoon (15May) is 10,450 lbs per hour. Of course thats without pods or a boom. Which engines? Guy CF6's. The higher burns (11,000) also due to payload/much longer stagelength differences. The 767-200 is optimized for the transatlantic market. |
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Kevin Brooks wrote:
snip This has been interesting, and informative; I hate to admit it ( :-) ), but I have learned a few things in this thread--though nothing that convinces me that either (a) we should not continue with procurement of the 767 tanker, or (b) there is something critically wrong with procuring the first 40 767's without multi-point capability up-front. And BTW--I don't find the assertion that we could keep the E's flying "as is" very convincing--ISTR there are real concerns over the availability of engines and related parts for the existing powerplants, so if you wanna go the "keep the E's" route you are realistically going to *have* to upgrade them. Thanks for the info, and I appreciate the discourse. Kevin, since were both tired of arguing the same points while lacking the data, here's a Congressional Research Service report from last September which presents both sides' arguments, as well as showing the costs and what assumptions went in to them, plus the effect on costs if any of those assumptions change. See: www.fas.org/man/crs/RL32056.pdf Of interest, my WAG that the engine struts (pylons) on the Es might be the main (extra) corrosion driver compared to the Rs was correct. I get lucky once in a while. Also, the report mentioned that the navy was already contracting out training and coast-to-coast tanking services, which I was unaware of. I haven't yet found out who they're contracting with or what kind of a/c they're using. Guy |
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Guy Alcala wrote:
snip Also, the report mentioned that the navy was already contracting out training and coast-to-coast tanking services, which I was unaware of. I haven't yet found out who they're contracting with or what kind of a/c they're using. Found it. They're contracting with an Irish company called Omega Air, which provides used 707-320s (they' got one or two in service so far) equipped with a pair of centerline Sargent-Fletcher (apparently now owned by Cobham PLC, formerly Flight-Refueling Ltd.) FR300 drogues. Omega has also apparently bought a fleet of used DC-10s, and plans to convert some of them into tankers in the future. At the moment, they're concentrating on hose-drogue refueling, both because the conversion is easier and ceaper, and because most air forces use it. the following is a quote from a 2001 AvLeak article: "Following retirement of its Grumman KA-6D and Lockheed KS-3A tankers, the U.S. Navy is exploring PFI operations through a recent $6.6 million air refueling contract with Flight International, Inc. and Omega Air. This involves 600 hours of tanker, EW training and other U.S. Navy support missions by Omega's dual probe-and-drogue equipped Boeing 707-320 through October this year, with renewal options up to 2005. These, and the USAF's massive KC-X requirement, are also hungrily earmarked for early pursuit by the FTSA contenders, who have also briefed 10 or more other countries on their proposals." This article apparently dates from 2000 so is a bit out of date, but it provides some useful info: http://www.nawcad.navy.mil/view_rele...m?article_id=8 Guy |
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sameolesid wrote:
Guy Alcala wrote in message ... sameolesid wrote: snip Just had a look at AFPAM 10-1403, which among other things lists military and CRAF a/c types for various roles and missions. Fuel burn for generic planning purposes of a KC-135R is listed as 10,921 lbs./hr. A CRAF B-767 (sub-type unstated) is listed as 10,552 lb./hr. A tanker version would have more drag (boom, receptacle and various fairings, never mind wing pods), so fuel burn of the two types appears to be essentially equal. Real world fuel burn for a 767-200 planned for a transatlantic this afternoon (15May) is 10,450 lbs per hour. Of course thats without pods or a boom. Which engines? Guy CF6's. The higher burns (11,000) also due to payload/much longer stagelength differences. The 767-200 is optimized for the transatlantic market. Thanks. I take it these are -200s and not -200ERs? It's not real critical, as I think we've established that fuel burn's a wash, but do you happen to know which CF6 model they're fitted with? There are a few options, depending on the MTOW of the particular a/c. Guy |
#46
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"Guy Alcala" wrote in message .. . Kevin Brooks wrote: snip This has been interesting, and informative; I hate to admit it ( :-) ), but I have learned a few things in this thread--though nothing that convinces me that either (a) we should not continue with procurement of the 767 tanker, or (b) there is something critically wrong with procuring the first 40 767's without multi-point capability up-front. And BTW--I don't find the assertion that we could keep the E's flying "as is" very convincing--ISTR there are real concerns over the availability of engines and related parts for the existing powerplants, so if you wanna go the "keep the E's" route you are realistically going to *have* to upgrade them. Thanks for the info, and I appreciate the discourse. Kevin, since were both tired of arguing the same points while lacking the data, here's a Congressional Research Service report from last September which presents both sides' arguments, as well as showing the costs and what assumptions went in to them, plus the effect on costs if any of those assumptions change. See: www.fas.org/man/crs/RL32056.pdf Of interest, my WAG that the engine struts (pylons) on the Es might be the main (extra) corrosion driver compared to the Rs was correct. I get lucky once in a while. Also, the report mentioned that the navy was already contracting out training and coast-to-coast tanking services, which I was unaware of. I haven't yet found out who they're contracting with or what kind of a/c they're using. I believe that would have been Omega Air, using a single 707 tanker; there was some info about it floating around in some of the pubs at the time, reporting its participation in an exercise or two. Brooks Guy |
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Guy Alcala wrote in message ...
Thanks. I take it these are -200s and not -200ERs? It's not real critical, as I think we've established that fuel burn's a wash, but do you happen to know which CF6 model they're fitted with? There are a few options, depending on the MTOW of the particular a/c. Guy They are 200ERs. AFAIK there are very few straight 200s. The engines on these are CF6-80C2B4's. |
#48
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sameolesid wrote:
Guy Alcala wrote in message ... Thanks. I take it these are -200s and not -200ERs? It's not real critical, as I think we've established that fuel burn's a wash, but do you happen to know which CF6 model they're fitted with? There are a few options, depending on the MTOW of the particular a/c. Guy They are 200ERs. AFAIK there are very few straight 200s. The engines on these are CF6-80C2B4's. Thanks. Guy |
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