More KC-46A woes....
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Some years ago I was involved in a multinational AAR study. One topic to be covered was practical maximum fuel loads for future tankers. But rather than believe manufacturers' glossy brochure boasts, I set the following conditions for the departure and arrival aerodromes: Sea Level, ISA, still air, 10000 ft runway. Hardly very demanding and reasonably typical of most large European aerodromes.
The US representatives immediately asked for 12000 ft - which we refused on the grounds that neither Heathrow nor Frankfurt were typical tanker bases.
After each group had crunched the numbers, the answer was that both the A310MRTT and A330MRTT could operate with max fuel under those conditions. The 73.5T ex-ba B767-200ER proposed by TTSC for the FSTA contract was also just able do so.
The US representatives immediately asked for 12000 ft - which we refused on the grounds that neither Heathrow nor Frankfurt were typical tanker bases.
After each group had crunched the numbers, the answer was that both the A310MRTT and A330MRTT could operate with max fuel under those conditions. The 73.5T ex-ba B767-200ER proposed by TTSC for the FSTA contract was also just able do so.
BTW, KC-46 will be based at McConnell and Altus. McConnell has a 12,000 ft runway and Altus 13,000 ft. So RAF has a 10,000 ft priority and USAF a 12,000 ft priority. Imagine that, different priorities for different users!
One more BTW. The KC-46 has more powerful engines and the high lift system from the -400ER, both of which improve runway performance when operating from more constrained forward bases. But of course these improvements just makes it a "Frankertanker." Imagine that.
All airplanes (generally) are designed to carry a payload, they can never reach max takeoff weight with just fuel. At max fuel they always have some take off gross weight margin which is used for carrying a payload.
The 767 and A330 are designed this way. Both carry fuel only in their wings. When they reach their fuel volume limit, they still have significant gross takeoff weight margin to carry passengers and cargo.
The MRTT, like the A330, carries all its fuel in its wings. It cannot trade payload for additional fuel.
The KC-46 has belly tanks. It can trade payload for additional fuel in those belly tanks.
The result is that the KC-46 has a ferry range advantage over the MRTT.
The 767 and A330 are designed this way. Both carry fuel only in their wings. When they reach their fuel volume limit, they still have significant gross takeoff weight margin to carry passengers and cargo.
The MRTT, like the A330, carries all its fuel in its wings. It cannot trade payload for additional fuel.
The KC-46 has belly tanks. It can trade payload for additional fuel in those belly tanks.
The result is that the KC-46 has a ferry range advantage over the MRTT.
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Ken, Voyager max take off 233t , max fuel theoretically 111t ish, ZFW with min crew 125 ish you do the math.
is it more expensive to extend a runway than to build ramps and extend hangars? I am not suggesting an answer - I am a know-nothing hence the question.
Last edited by t43562; 5th Nov 2014 at 17:06. Reason: clarify.
The point I was making was that the ac can trade payload for fuel and incidentally does carry fuel other than in the wings. In other words it can reach max take off with fuel alone. Come to think of it so could the Tristar KC1/K1!
Some years ago I was involved in a multinational AAR study. One topic to be covered was practical maximum fuel loads for future tankers. But rather than believe manufacturers' glossy brochure boasts, I set the following conditions for the departure and arrival aerodromes: Sea Level, ISA, still air, 10000 ft runway. Hardly very demanding and reasonably typical of most large European aerodromes.
The US representatives immediately asked for 12000 ft - which we refused on the grounds that neither Heathrow nor Frankfurt were typical tanker bases.
After each group had crunched the numbers, the answer was that both the A310MRTT and A330MRTT could operate with max fuel under those conditions. The 73.5T ex-ba B767-200ER proposed by TTSC for the FSTA contract was also just able do so.
The US representatives immediately asked for 12000 ft - which we refused on the grounds that neither Heathrow nor Frankfurt were typical tanker bases.
After each group had crunched the numbers, the answer was that both the A310MRTT and A330MRTT could operate with max fuel under those conditions. The 73.5T ex-ba B767-200ER proposed by TTSC for the FSTA contract was also just able do so.
The 767-2C/KC-46 is designed for MTOW (415,000 lbs) at sea level from a 8,400 ft. runway up to corner point temp (+15C).
KenV, thanks for the objective and informed comments - in sharp contrast to most of what's been posted on this thread.
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is it more expensive to extend a runway than to build ramps and extend hangars? I am not suggesting an answer - I am a know-nothing hence the question.
Thread Starter
If there was any BS, then it was from Boeing!
Whether ba operated 767-200ERs or 767-300ERs is nihil ad rem. The point is that they struggle to operate from a 10000 ft balanced field in ISA / still air conditions at MTOW.
Those who've operated the ba aircraft on hot days at high AUW confirm that the take-off performance is utterly woeful under such conditions. Which rather backed up the Boeing FSTA bidder's comment "Runway performance? Yes, Airbus has got us beaten there!"
As for Voyagers evacuating whenever there's a significant weather event, that certainly isn't true at home base - but might be so in the S.Atlantic due to the inadequate hangar.
Still, until the Frankentanker actually flies (perhaps next year, but who knows...??), no-one will really know whether it can actually operate at MTOW from anything less than a 12000 ft balanced field in still-air / ISA / SL conditions.
Whether ba operated 767-200ERs or 767-300ERs is nihil ad rem. The point is that they struggle to operate from a 10000 ft balanced field in ISA / still air conditions at MTOW.
Those who've operated the ba aircraft on hot days at high AUW confirm that the take-off performance is utterly woeful under such conditions. Which rather backed up the Boeing FSTA bidder's comment "Runway performance? Yes, Airbus has got us beaten there!"
As for Voyagers evacuating whenever there's a significant weather event, that certainly isn't true at home base - but might be so in the S.Atlantic due to the inadequate hangar.
Still, until the Frankentanker actually flies (perhaps next year, but who knows...??), no-one will really know whether it can actually operate at MTOW from anything less than a 12000 ft balanced field in still-air / ISA / SL conditions.
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The point I was making was that the ac can trade payload for fuel and incidentally does carry fuel other than in the wings. In other words it can reach max take off with fuel alone. Come to think of it so could the Tristar KC1/K1!
And about those TriStars: fuel capacity of the -200 is 180Klb and OEW is 248Klb. So fully fueled an empty TriStar weighs 428Klb. MTOGW is 466Klb. So fully fueled a TriStar can still carry a 38Klb payload. If RAF TriStars can reach MTOGW with fuel alone, then they also must have additional tanks installed.
No airliner has ever been designed to be able to reach MTOGW with fuel alone and no payload. EVERY airliner has two knees in its payload/range curve. Indeed there are precious few aircraft of any kind that can reach MTOGW with fuel alone simply because the point of most aircraft is to transport a payload, and not to transport itself. Its called a PAYload for a reason. That's how the operator makes money with it. Flying around with zero payload is a hugely money losing proposition.
Tanker aircraft are an exception in that the payload is fuel. If the plumbing is designed properly, the payload fuel can be burned by the engines. This is NOT always the case in tanker aircraft. In some tankers, the payload fuel can only be offloaded and cannnot be transferred to the wing tanks for use by the engines.
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If there was any BS, then it was from Boeing!
Whether ba operated 767-200ERs or 767-300ERs is nihil ad rem. The point is that they struggle to operate from a 10000 ft balanced field in ISA / still air conditions at MTOW.
Whether ba operated 767-200ERs or 767-300ERs is nihil ad rem. The point is that they struggle to operate from a 10000 ft balanced field in ISA / still air conditions at MTOW.
Interesting. The MRTT both Northrop Grumman and Airbus offered to USAF had ONLY wing fuel. No belly fuel. None. It could not reach max take off gross weight (MTOGW) with fuel alone. The RAF must have installed additional tankage in their Voyagers.
No airliner has ever been designed to be able to reach MTOGW with fuel alone and no payload.
No airliner has ever been designed to be able to reach MTOGW with fuel alone and no payload.
You say you were on the NG team that offered the A330??
If there was any BS, then it was from Boeing!
Whether ba operated 767-200ERs or 767-300ERs is nihil ad rem. The point is that they struggle to operate from a 10000 ft balanced field in ISA / still air conditions at MTOW.
Whether ba operated 767-200ERs or 767-300ERs is nihil ad rem. The point is that they struggle to operate from a 10000 ft balanced field in ISA / still air conditions at MTOW.
F.A.R. TAKEOFF RUNWAY LENGTH REQUIREMENTS - STANDARD DAY - 9,100 ft.
Make it a +15 deg C day, and it increases to about 9,500 ft.
For the 767-300ER with the more powerful PW4062 engines (which will be on the 767-2C/KE-46), and those field lengths drop to about 8,200 ft. and 8,600 ft., respectively
These numbers are out of FAA approved 767 airplane manuals.
Where did you pull your numbers from?
Thread Starter
KenV wrote:
You're not seriously expecting anyone to believe wiki as your reference source, are you?
Did you even know the capability of the Northrop Grumman offer?
As for
Oh really? Which tankers? Apart from the KC-135Q, that is.
If the level of knowledge you've exhibited on this forum is anything to go by - and you really worked for them, it's hardly surprising that Northrop Grumman's offer failed.
Interesting. Wiki claims the source of their data is Boeing, and according to wiki, the "Takeoff distance at MTOW (sea level, ISA)" is 8,300 ft for both the -200ER and the -300ER.
Did you even know the capability of the Northrop Grumman offer?
As for
In some tankers, the payload fuel can only be offloaded and cannnot be transferred to the wing tanks for use by the engines.
If the level of knowledge you've exhibited on this forum is anything to go by - and you really worked for them, it's hardly surprising that Northrop Grumman's offer failed.
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No, the offer to the USAF had the A330 standard fuel configuration. The RAF also have the standard configuration. The MRTT for the other markets has the standard configuration. No extra tanks were fitted or need to be fitted. No, the standard A330 does not have fuel only in the wings. The fuel load has already been covered.
You say you were on the NG team that offered the A330??
You say you were on the NG team that offered the A330??
And yes, I was on the NG team that co-developed the boom and the RARO (remote aerial refueling operator) station. At that time Boeing's offer was based on the KC-135 boom and our boom was far superior. And our proposal won. Our boom forced Boeing to do a total redesign based on the KC-10 boom for their next effort. Sadly, NG was not part of the next effort.
Last edited by KenV; 5th Nov 2014 at 20:28.
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You're not seriously expecting anyone to believe wiki as your reference source, are you?