With the final re-bid tanker proposals from Boeing and Northrop Grumman/EADS expected later this fall, speculation abounds that Boeing is considering offering the larger 767-400ER in place of the 767-200ERX.The FlightBlogger art department decided to peek into the looking glass and see what a 767-400ER tanker (KC-764) would actually look like. The point of the (extremely rough) diagram is to illustrate one of the key challenges a 767-400ER platform would face. The -400ER is 42.3 feet longer than the -200ERX. The takeoff run -400ER at MTOW would be significantly longer than the -200ERX and with the addition of the refueling boom, the rotation angle could be a significant factor as well. I've (roughly) estimated that the 767-200ER would have 7.5 degree rotation angle before tail strike, but the 767-400ER would only have 4 degrees nose-up before striking the tail on the runway.
Though, Boeing has already proven itself adept at compensating for this by adding tail strike protection into the 777-300ER, reducing the aircraft's take off roll by 600 feet.
According to our friends at Leeham, "The Amended [Draft Request For Proposals] now ranks runway performance as a "3" in importance (on a scale of 1 to 3, with one being most important)." So, it may be a moot point when it's all said and done.
The original KC-767 was set to have the -400ER (777-style) flight deck, so right out of the box Boeing is able to deliver an enhanced flight deck to the USAF. So why not choose the 767-400ER all along?
Boeing made the claim that the footprint of the tanker was key to basing flexibility. More importantly, Boeing followed the original terms of the RFP, which said it wouldn't give extra credit for a larger tanker, whereas Northrop/EADS went beyond by giving "more" to the USAF.
Looking at this through a commercial lens for a moment, the 767-200ERX was to be the platform for which the KC-767 was born from. Boeing was able to immediately turn that product into a commercial application to avoid the necessity of an ITAR waiver. They wouldn't have been able to do it as easily if the KC-767 was first.
With that inspiration in mind, the -200ERX was to live its life as a freighter in the 767-200LRF, bolstering the 767 line beyond one tanker per month. If Boeing was to round out its freighter family, then making a 767-400ER freighter, which would've been the foundation for the KC-764, Boeing would've stepped on the toes of the 777F, hardly a good product strategy.
If Boeing offers the 767-400ER, what might EADS and Northrop do? Instead of using the A330-200, the NG/EADS team might offer the A330-200F. What's the benefit? Currently, NG/EADS has to convert every A330-200 to a freighter/tanker configuration from a passenger aircraft. Switching to the A330-200F, which wasn't around when the A330-200 was first offered to the USAF, saves sizable time and cost in production. In 2007, Northrop said that it would "inevitably" switch to the A330-200F anyway; a claim Northrop later backed away from, but never denied saying it.
Also, the A330-200 is fitted with twin General Electric CF6 engines, though if the A330-200F is offered, NG/EADS will likely switch to Pratt & Whitney PW4000 engines that are only available along with Rolls Royce Trent 700. NG/EADS won't be offering non-US built engines.
With PW4000 engines on both Boeing and Airbus tankers, does this increase the chances of a split buy?
Wait, I've gone cross-eyed. This tanker makes my head hurt.
on August 19, 2008 8:33 PM | Reply
Why not the 767-300ER??
Is the touted increase in size to match the A330's capacity?
on August 19, 2008 11:46 PM | Reply
Your assumption about the rotation angle is wrong. The 767-400 has a longer (taller) main gear, which makes the tail way higher than the -300.
on August 20, 2008 12:08 AM | Reply
If only the USAF knew what it wanted. KC-X is supposed to replace the KC-135, which the KC-767 (-200) does quite well. The follow-on program KC-Y is supposed to replace the KC-10... IOW, this is the large tanker program for which the KC-30 is best suited.
I do not trust the USAF. Repeat demonstrations of pure incompetence lead me to this conclusion. They quickly ignored their own criteria, they fell prey to a "bigger is better" mentality, they literally lied to Boeing... Robert Gates should have fired a few more people in the organization, beginning with Sue Payton.
on August 20, 2008 5:26 AM | Reply
a.net folklore claims the -400ER is a poor lifter (compared to A332).. would Boeing have to dust off the -400ERX if it wanted to do this? We already know that the -200 based tanker is a good deal heavier than its commercial cousin.
I suppose hanging a pair of GP7200's isn't much in terms of the wider tanker derivative (i.e risk), but the -400ERX(T) would be even more of a paper aeroplane.
on August 20, 2008 12:07 PM | Reply
I still don't understand why Boeing doesn't add lower cargo hold aux fuel tanks to the KC-767AT, and protest the 7,000' runway performance at MTOW.
Instead, have the RFP read 7,000' to meet the fuel offload chart, and then be able to carry additional fuel (with extra points) with a longer takeoff run.
Offering the "KC-764" undermines Boeing's entire "Right Sized" argument, and simply begs giving the contract to NG/EADS based on equal capacity, at lower cost, with higher runway performance.
on August 20, 2008 12:12 PM | Reply
The 767-400 main gear is 43 cm longer than the gear for the 767-200. From your drawings, it would appear that the point where the tail would strike is about 10 meters behind the gear, and that point would move back 5 meters on the -400. If that is the case, a 7.5 degree tail strike angle on the -200 would yeild a 5 degree angle on the -400 if the gear wasn't extended, but with the 43 cm extension it's 6.64 degrees.
Granted 6.6 degrees is less than 7.5, but it isn't a prohibitive difference.
on August 20, 2008 5:17 PM | Reply
Where is the Air Force going to get the funds to completely overhaul their current KC-135 tanker facilities? Neither the A330 or the 764 can use the current fueling hardstands or hangars (while they can use the KC-10 facilities). This is going to be a multi-billion dollar line item for the AF that no one has brought up. Which is also the whole reason Boeing keeps harping on the 'right sized' 762.
on August 20, 2008 9:19 PM | Reply
Years ago, as a Biology lab TA, I structured the practical exam so as to rank the students (victims) in alphabetical order. I knew what they knew.
My belated apologies to Mr. Zytnik (though everybody passed). Kinda like the "Tanker Contest"
on August 21, 2008 4:37 PM | Reply
Does anyone know whether we're talking about the 767-400ER or the Longer Range 767-400ER (767-400ERX) ordered by Kenya Airways before being dropped by BCA in favour of Chronic Snoozer? The long-range fuel set up might offer advantages now, even though airlines apparently couldn't live with the extended flight times that came with the extra range at the 767's lower cruise speed (resulting from the straighter wing originally driven by fuel burn considerations when the 767 was designed in the shadow of the 1973 energy crisis, i seem to remember...).
Just a thought.
on August 29, 2009 11:39 AM | Reply
Why not the 767-400ER, with the fuselage length of the 767-300ERF. (higher -400 gear, shorter fuselage length ------ better tailstrike angle)
The aircraft could be powered by GE GEnx2B engines, specialy designed for the 747-8 (smaller fan and optimised for bleed extraction.
on September 16, 2009 1:26 AM | Reply
hi
presented same idea on 'Boeing 767-400 ER as new KC-767 alternative'
http://planetalks.blogspot.com/2008/08/boeing-767-400-er-as-new-kc-767.html - Friday, August 15, 2008