Comments on: Interrogative Texaco

By: robur

robur — Fri, 26 Oct 2007 06:43:26 +0000

If the lifespan of the B-52 can be extended by decades, the KCs can be extended as well. If fuel economy is the problem, they can be re-engined. Even that would be cheaper than new aircraft. The services do not need new tanker aircraft.

By: irtusk

irtusk — Fri, 26 Oct 2007 00:40:47 +0000

> Still, how does the airborne refueling time of a plane on a boom compare to one on a drogue? Could be that refueling 3 planes in succession off a single boom is still faster than 3 in parallel off 3 drogues.
boom:
KC-30 = 1200 gal/min
KC-10 = 1100 gal/min
KC-135 = 1000 gal/min
KC-767 = 900+ gal/min
center hose:
KC-30 = 600 gal/min
KC-767 = 600 gal/min
KC-10 = 470 gal/min
wing hose:
KC-30 = 420 gal/min
KC-767 = 400 gal/min
KC-135 = 400 gal/min
raw offload capacity of KC-30
1 boom = 1200 gal/min
3 hose = 600+420+420 = 1440 gal/min
another important factor to consider is speed of the receiver. No current ‘small’ plane can max out a KC-135 boom (1000 gal/min) except the F-111, and that only for a short period until some of the smaller fuel tanks fill up
i’m not sure of the actual numbers, but let’s say that the standard fighter can accept 800 gal/min (probably being very generous here)
adjusted offload capacity of KC-30:
1 boom = 800 gal/min
3 hose = 600+420+420 = 1440 gal/min
that’s a pretty substantial difference
yes, big planes (C-5, C-17, B-52, etc) should use booms, but there’s no reason for small planes to use them

By: George Skinner

George Skinner — Wed, 24 Oct 2007 18:12:51 +0000

AK,
I didn’t mean to imply that there are any fatigue problems with the 767 airframe, just that fatigue isn’t the big problem with the existing KC-135 airframe. The bigger problems with the KC-135 are fuel efficiency and supporting an aging design. The 767 is an improvement over the KC-135 in those respects, but not exactly a long-term solution given that it’s also a 25-year old design.
Regarding boom vs. drogue refueling, 3 drogues vs. 1 boom certainly provides the ability to refuel more than one plane at a time. However, the advantage of a boom is supposed to be a higher fuel transfer rate compared to a drogue. The higher refueling rate is pretty important when you’re trying to refuel large aircraft like bombers or cargo planes, not so much when you’re refueling tactical aircraft. Still, how does the airborne refueling time of a plane on a boom compare to one on a drogue? Could be that refueling 3 planes in succession off a single boom is still faster than 3 in parallel off 3 drogues.

By: Emmett

Emmett — Wed, 24 Oct 2007 14:18:47 +0000

With more than a few years in aviation I can say the following: the Airbus is a competent product from a manufacturer that makes disposable airframes.
The Boeing product is probably more maintainable and more repairable.
As a bargaining technique I would look hard at the airbus, then I’d take every advantage of the fact that the development costs of the Boeing are long since paid. I prefer to have military products made within our shores by people I can drag in front of Congress.
But my biggest concern with either is they are basic civilian airliner airframes. We routinely contract aircraft for a 20 years service life and then fly them for 40 in the military. I want overbuilt airframes. I want carrier-qualified airframes, not because that is thier role, but because they have to last. I worry about both airframes in that respect.
I personally know of a P-3 that will leave Guam in pieces because we broke something solid in the wingbox in a typhoon. But it brought us home.
Emmett

By: irtusk

irtusk — Wed, 24 Oct 2007 06:13:16 +0000

> Given that the 767 is in service by the 1000s, wouldn’t it’s fatigue life & stress points would be pretty well known by now?
the A330 has been in service plenty long, in fact they’re already taking orders for it’s replacement (A350)
> If the contract comes down to gas-only considerations (yes there is a “tanker mafia”) the Boeing product will win going away.
how so?
if the KC-30 carries more gas further and costs less to boot …
as far as ‘booms in the air’ arguments i see certain places, that’s just stupid talk. If they were really concerned about booms in the air, the F-35A would have a refuelling proble like the B and C variants. You can tank 3 planes with probes at once from one plane. Tripling the number of planes that can be refuelled at once seems a heck of a lot more important than some marginal percentage argument about available airports and ramp space.

By: ak

ak — Wed, 24 Oct 2007 01:46:57 +0000

Given that the 767 is in service by the 1000s, wouldn’t it’s fatigue life & stress points would be pretty well known by now? The program seems to bordering on the ridiculous as a whole, but I don’t think the aircraft itself is in any way unsuited to the role.

By: George Skinner

George Skinner — Tue, 23 Oct 2007 22:09:46 +0000

The problem with Boeing's proposal is that it's based on an aircraft nearing the end of its product life (i.e. it's about to be discontinued by the manufacturer.) The key problems with the KC-135 fleet is 1) the airframes are wearing out, 2) the planes are increasingly difficult to support because the parts are no longer available, and 3) they're not very fuel-efficient. The 767 will address 1), but using an older design isn't going to do much for 2) or 3). And even 1) isn't the biggest problem for the KC-135s, as they're early model 707s without windows. They've got a pretty sturdy structure already because Boeing was incredibly aware of the DH Comet fatigue failures a few years earlier, and the lack of windows reduces a major source of fatigue on the fuselage. Unfortunately, Boeing is in no position to offer the 787 as a tanker to get new technology in there, and the 777 is really too big. I think they were hoping to get a fast deal done with the AF to keep the 767 line open a little longer and make some more money from an existing product at the end of its life. On the other hand, I'm not sure the A330 is such a great platform either, given the differences in design philosophy between Airbus and Boeing. Airbus has always been more about fly-by-wire for "carefree handling" (i.e. let the computer limit how the pilot can maneuver) and small engines optimized for cruise efficiency. Boeing's philosophy is to use FBW, but let the pilot bend the plane if needed, and also put on relatively larger engines for take-off power and throttle back in flight. Both approaches work out fairly well for the civilian market, but the Boeing one seems like a better fit for the military application. If you're trying to avoid a SAM or fly at low level, shouldn't the pilot have more power and control authority?

By: Beancounter

Beancounter — Tue, 23 Oct 2007 13:43:13 +0000

If you were still flying, perhaps you would think twice about insulting you fellow Americans by calling them “pencil-necked”, when your life depends on the work they do. A few of those “pencil-necks” I knew could pull one of your ears out through the other for such a comment. And what the hell do we care if Boeing loses the contract..let’s give it to the French.

By: SMSgt Mac

SMSgt Mac — Tue, 23 Oct 2007 12:14:18 +0000

I am on record many times as NOT being an Airbus fan for a lot of reasons–most importantly they do not have a true aviation mindset and culture. I also believe as lead contractor, Northrop Grumman (disclosure: my employer) and AF contract management can do for the KC-30 what the AF did with the KC-10,which in early DC-10 guise was a problem-riddled beast. Taxpayer dollars helped make the later DC-10 a great product (the GE CF-34 engine is another example of taxpayer dollars making a better commercial product).
If the contract is competed sans politics, it will go to the KC-30 if gas/tanker ratio is more important than numbers of tankers and the cargo/secondary mission is given its proper due. If the contract comes down to gas-only considerations (yes there is a “tanker mafia”) the Boeing product will win going away.
As to where the contract might be going, I find it interesting that in this week’s AV Week, Boeing’s ad punches up the point they aren’t offering any more than what they think the AF needs: a ‘best value’ pitch. This is a marked departure from their past governemnt competion strategies where they just emphasized the ‘best’ aspect.

By: Pinch

Pinch — Tue, 23 Oct 2007 10:45:59 +0000

Solomon,
Nice dig on the game there, pal! One in a million catch — gotta hand it to Miles and the Bayou boys. Ballsy move. AU had great coverage, as well, on that pass.
I agree with your comment. The subsidies that pour into Airbus are by and large the main discriminator between the aircraft. Going with Boeing would be my vote.
Pinch