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Old 5th Nov 2014, 16:28   #81 (permalink)
 
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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.
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Old 5th Nov 2014, 16:33   #82 (permalink)
 
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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.
Isn't this interesting? One the one hand there are those who shout loudly that MILCON is never a deciding factor and that the purchaser will always modify their facilities to accomodate a chosen weapon system. But on the other hand there is this report that states that the constraints of existing facilities was a significant driver in an international tanker selection process. Imagine that.

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.
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Old 5th Nov 2014, 16:42   #83 (permalink)
 
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Originally Posted by KenV View Post
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.
Do you believe the stuff you spouting?

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Old 5th Nov 2014, 16:43   #84 (permalink)
 
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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.
Hmmmm. 111 + 125 = 236, 3t more than MTOGW. So the Voyager can NEVER reach max fuel and even with zero payload and min crew, one cannot fill the tanks. Odd design. The numbers we crunched when I was with N-G came out quite a bit differently.
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Old 5th Nov 2014, 16:47   #85 (permalink)
 
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Do you belie the stuff you spouting?
Believe? I had no idea this was a religious discussion.
What airplane facts did I get wrong?
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Old 5th Nov 2014, 17:05   #86 (permalink)
 
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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.

Last edited by t43562; 5th Nov 2014 at 17:06. Reason: clarify.
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Old 5th Nov 2014, 17:39   #87 (permalink)
 
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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!
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Old 5th Nov 2014, 18:18   #88 (permalink)
 
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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.
Sorry BEagle, but I have to call BS. First off, BA never even had 767-200ERs, they were -300ERs. And 767 takeoff performance is just fine (as 1000 in-service passenger and freighter 767s can attest).
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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Old 5th Nov 2014, 18:32   #89 (permalink)
 
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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.
That depends. How much more runway vs how much more ramp? As for hangars, they're pricey. I understand (but cannot confirm) that Voyagers cannot fit in the hangars at their home base. Rather than pay to enlarge the existing hangars they evacuate the aircraft every time there is a major weather event.
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Old 5th Nov 2014, 18:54   #90 (permalink)
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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.

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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Old 5th Nov 2014, 19:10   #91 (permalink)
 
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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!
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.

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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Old 5th Nov 2014, 19:23   #92 (permalink)
 
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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.
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.
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Old 5th Nov 2014, 19:31   #93 (permalink)
 
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Originally Posted by KenV View Post
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, 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??

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Old 5th Nov 2014, 19:41   #94 (permalink)
 
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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.
Sorry BEagle, but I'm looking at the FAA approved numbers - you know, the numbers that the airlines use. 767-300ER, with RB211-524H engines, MTOW of 415,000 lbs. :
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?
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Old 5th Nov 2014, 19:47   #95 (permalink)
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KenV wrote:
Quote:
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.
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
Quote:
In some tankers, the payload fuel can only be offloaded and cannnot be transferred to the wing tanks for use by the engines.
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.
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Old 5th Nov 2014, 20:12   #96 (permalink)
 
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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 are correct, I neglected to mention the tail tank. But the bottom line was that with the standard A330 fuel configuration, the MRRT offered could not reach MTOGW with fuel alone.

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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Old 5th Nov 2014, 20:16   #97 (permalink)
 
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…or the 32 tonnes in the centre tank.
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Old 5th Nov 2014, 20:18   #98 (permalink)
 
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You're not seriously expecting anyone to believe wiki as your reference source, are you?
Are you similarly dismissive of the FAA approved flight manuals?
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Old 5th Nov 2014, 20:24   #99 (permalink)
 
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When they put the CFMs on the KC135 and called the tanker of the 21st century it sounds like they were right.
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Old 5th Nov 2014, 20:33   #100 (permalink)
 
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You're not seriously expecting anyone to believe wiki as your reference source, are you?
Wiki claims they used Boeing data and its written and published. If that offends you, so be it. I'm fine with that. And if you'd rather trust the memory of a many years ago competition, that's fine with me also.
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