I always think it's a bit odd that programs like this want to reinvent the wheel. There are available wing pods out there right now, for instance on the A330MRTT. Why do the USAF and other stakeholders need something that has to fit precisely to their specifications and instead just buy the proven systems in?

Companies like Cobham could supply the units tomorrow. Or am I overlooking something major? It could potentially save the taxpayers of the USA millions of dollars.

If purchased from Cobham how many jobs do they have in US congressional districts?

Channex757 wrote:

I always think it's a bit odd that programs like this want to reinvent the wheel. There are available wing pods out there right now, for instance on the A330MRTT. Why do the USAF and other stakeholders need something that has to fit precisely to their specifications and instead just buy the proven systems in?

Companies like Cobham could supply the units tomorrow. Or am I overlooking something major? It could potentially save the taxpayers of the USA millions of dollars.

The problem is the interaction of WARP with the KC-46 wing platform and the PW engine installation. (the KC767's with WARPS are GE CF6-80C2 powered)

The RP-910E-75 Wing Aerial Refueling Pod (WARP) and FR-600-84MDR Centerline Drogue System (CDS) are both manufactured by Cobham for the KC-46 program :

See : http://www.cobham.com/mission-systems/a ... datasheet/

Both KC-46 refuelling systems are developments from the A330MRTT units.

See : http://www.cobham.com/mission-systems/a ... datasheet/

Right, so it's this interaction issue. Thanks for the info. Why is it proving to be a problem? The engine installations are almost identical visually so there must be something that's causing the problems, such as the engine weight or the pipework within the wing.

Channex757 wrote:

Right, so it's this interaction issue. Thanks for the info. Why is it proving to be a problem? The engine installations are almost identical visually so there must be something that's causing the problems, such as the engine weight or the pipework within the wing.

Or the stiffness of the wing itself . . . This is where a thinner, more flexible wing may introduce more dynamic issues.

bt

I'm reminded of all the people who wonder why they didn't also stick winglets on those wings. Certainly that sort of thing can have unforeseen consequences like this...

The Italian KC-767A was also delayed by wing flutter issues when adding WARPS.
The 767 wing was not designed to accept large external loads outboard of the engines and had to be strengtend and/or modfied at several critical positions for the KC-767A.

.
By selecting the PW4062* engine i.s.o. the GE CF6-80C2B6F/-7F (as installed at the KC-767A) for the KC-46A, the USAF and Boeing introduced a large additional risk for more delays, because the entire flight envelope has to be cleared again for flutter issues with these WARPs installed. If some new flutter issues are revealed during flight testing the wing structure has to be strengtend /or modified again at certain positions and the whole flight envelope has to be checked again, a very time consuming effort, requiring many test flights with different loads and/or speeds at all certfied altitudes.

* The PW4062 has a different weight and other dimensions (length and diameter) than the GE CF6-80C2B6F/-7F engine.

Note : The A330/340 wing was designed as a common wing platform for both the A330 (2 engines) and the A340 series (4 engines) and the warps are installed at the not used wing hardpoints for the outboard A340 engine positions..

747classic wrote:

The Italian KC-767A was also delayed by wing flutter issues when adding WARPS.
The 767 wing was not designed to accept large external loads outboard of the engines and had to be strengtend and/or modfied at several critical positions for the KC-767A.

OK, here's my dumb aeronautical engineering 101 question - would the winglets currently offered on new 767's help with this issue? I'm sure it's been discussed but I'd like to hear a "fresh" reasoning on it.

Regards

Two 767-2C's seen in the EMC yesterday:


A pair of 767-2C's (KC-46A) by Woodys Aeroimages, on Flickr

KarelXWB wrote:

Two 767-2C's seen in the EMC yesterday

Left : L/N 1102 C/N 41858 B767-2LKC 16-46009 USAF KC-46A (VH009) LRIP1

Right : L/N 1100 C/N 41856 B767-2LKC 16-46008 USAF KC-46A (VH008) LRIP1

PC12Fan wrote:

747classic wrote:

The Italian KC-767A was also delayed by wing flutter issues when adding WARPS.
The 767 wing was not designed to accept large external loads outboard of the engines and had to be strengtend and/or modfied at several critical positions for the KC-767A.

OK, here's my dumb aeronautical engineering 101 question - would the winglets currently offered on new 767's help with this issue? I'm sure it's been discussed but I'd like to hear a "fresh" reasoning on it.

Regards

At my school, the principle of structural dynamics was not taught in the 101 courses. It was taught later and I did not do well in it.

But to give you a semi-educated guess. Probably not. If you get a flutter problem, usually to solve it, you stiffen up the structures. Adding weight would usually reduce the resonance frequency of the structure and make it worse. You can also try active or passive dampening or change the air flow so as to change the aero loads that is causing your flutter. It can be complicated and I would have done worse if it was taught in a 101 course:)

bt

The Pentagon is expected to put its seal of approval on Boeing’s new KC-46 tanker later this month.

“we believe that the aircraft has met all of the wickets that are required to meet milestone C, but of course that remains to be seen, so I’ll say stay tuned on that,” the Secretary of the Air Force Deborah Lee James said in a briefing Wednesday.

See : http://www.heraldnet.com/business/penta ... 46-tanker/

WIederling wrote:

Throwing resources at a late program make it .... later

(original from "Mythical Man Month: .. throwing manpower at a late ... )

Isn't that Boeing SOP? Throw a bunch of people at the problem and see what sticks and when your done hand out the pink slips.

WIederling wrote:

But Boeing boasts Hnow How from deeply ingrained DNA going back five ++ decades of "we know about tankers".
Where is it?

We know the answer to that. All the people involved in the design and building of the KC-135 retired/passed on. The same can be said for the people involved with the KC-10 over at MD. The one facility that did have experience with tankers is now closed and all their people spread to the four winds.

Pentagon approves production (milestone C) of Boeing KC-46 tanker

See : http://www.heraldnet.com/business/penta ... 46-tanker/

Yes, cool. Finally the USAF will start getting these capable tanker transports.

Not so fast. The first aircraft will have to undergo some sort of rework because the initial WARP's are not operational.

LMP737 wrote:

All the people involved in the design and building of the KC-135 retired/passed on. The same can be said for the people involved with the KC-10 over at MD.

so Boeing appears to be worse off than Airbus in that domain.
Airbus knew that they started rather fresh. ( beyond some obscure projects from WWII times involving Mr Kracht )
Boeing did not know/realize that they did know nothing much anymore.
( Rumsfelds unknown unkowns "shadocks in the walls" hit again.)

KarelXWB wrote:

Not so fast. The first aircraft will have to undergo some sort of rework because the initial WARP's are not operational.

AFAIK the KC-46A has removable wing air refuelling pods, so the flight envelope has to be fully certified with and without the pods installed..
Initially the aircraft can be operated without the wing pods installed.

LN 1100 outside the assembly halls:


16-46008 USAF Boeing KC-46A Pegasus (767-2LKC) VH008 - C/N 41856 / LN 1100 by Woodys Aeroimages, on Flickr

L/N 1100 C/N 41856 B767-2LKC 16-46008 USAF KC-46A (VH008) LRIP1 now fully "mothballed"

KPAE, August 15 2016



Original uploaded by Chris Edwards, see : http://www.flickr.com/photos/woodysaero ... 013207725/

Oeps Karel, we performed the same action at the same time.

747classic wrote:

Pentagon approves production (milestone C) of Boeing KC-46 tanker

See : http://www.heraldnet.com/business/penta ... 46-tanker/

Nice! Reminds me of the good old days when people here on a.net counted frames on the first tanker frames to emerge just to figure out its length!

KarelXWB wrote:

Not so fast. The first aircraft will have to undergo some sort of rework because the initial WARP's are not operational.

FWIW the article above says:

Boeing expects to deliver the first batch of combat-ready tankers to the Air Force by January 2018, only five months later than originally planned.

http://www.seattletimes.com/business/bo ... e-tankers/ emphasizes the current agreement covers the initial 19 frames and:

A decision to approve full production — the most lucrative phase — has slipped to March 2018 from September 2017, the Air Force disclosed in March, as a result of cumulative delays in aircraft development from technical issues, such as wiring and the refueling system.

But it's good news none the less. The impediments to income flowing in are largely removed. Presuming there's no more ghosts in the closet, it seems it's just a matter of time till the full production contract is signed. Given how many write-offs Boeing has already taken for this program, there will be howls if any more big ones come.

While being on time is preferred, 5 months is not to bad a delay given the grand scheme of things.
Just be glad it's not 5 years. Oh wait, they wasted 15 years with all the contract disputes

The USAF awarded the Boeing company a $2.8B contract, today. The contract is to build the first 19 KC-46As in two blocks. LRIP Block 1 will be 7 new tankers followed by block 2 which will be 12 tankers. All 19 KC-46As are expected to be delivered by 24 August 2018. The contract includes spares, spare engines, and wing mounted air refueling pods.

http://www.msn.com/en-us/money/companie ... li=BBnb7Kz

kc135topboom wrote:

The USAF awarded the Boeing company a $2.8B contract, today. The contract is to build the first 19 KC-46As in two blocks. LRIP Block 1 will be 7 new tankers followed by block 2 which will be 12 tankers. All 19 KC-46As are expected to be delivered by 24 August 2018. The contract includes spares, spare engines, and wing mounted air refueling pods.

http://www.msn.com/en-us/money/companie ... li=BBnb7Kz

So even for this first contract Boeing has to solve the wing mounted pod issue.

mjoelnir wrote:

So even for this first contract Boeing has to solve the wing mounted pod issue.

Yes, but Boeing and Cobham PLC have refueled planes from the WARPs so they just need to deal with the flutter issue (which I believe is the problem). The USAF has said they expect the WARPs to be ready by next year (October 2018) which is fine considering I believe only USN / USMC aircraft use them so for normal USAF operations, it's a non-issue not having them equipped. And even then, the center drogue system can refuel USN / USMC aircraft so the KC-46A can be used in mixed-Service operations.

Stitch wrote:

mjoelnir wrote:

So even for this first contract Boeing has to solve the wing mounted pod issue.

Yes, but Boeing and Cobham PLC have refueled planes from the WARPs so they just need to deal with the flutter issue (which I believe is the problem). The USAF has said they expect the WARPs to be ready by next year (October 2018) which is fine considering I believe only USN / USMC aircraft use them so for normal USAF operations, it's a non-issue not having them equipped. And even then, the center drogue system can refuel USN / USMC aircraft so the KC-46A can be used in mixed-Service operations.

I wouldn't say its a non-issue. This tanker was bought to support all DOD aircraft not just USAF aircraft. So this is just as in important as the boom not working

The KC-46 also has in internal centerline hose and drogue system. I have not heard if there are any issues with that system. Does anyone know anything?

The experts can confirm, but I think if the centerline is configured for drogue it cannot be reconfigured in flight, the entire mission is single use.

par13del wrote:

The experts can confirm, but I think if the centerline is configured for drogue it cannot be reconfigured in flight, the entire mission is single use.

They can use either the boom or the CDS on the same flight.

INFINITI329 wrote:

Stitch wrote:

mjoelnir wrote:

So even for this first contract Boeing has to solve the wing mounted pod issue.

Yes, but Boeing and Cobham PLC have refueled planes from the WARPs so they just need to deal with the flutter issue (which I believe is the problem). The USAF has said they expect the WARPs to be ready by next year (October 2018) which is fine considering I believe only USN / USMC aircraft use them so for normal USAF operations, it's a non-issue not having them equipped. And even then, the center drogue system can refuel USN / USMC aircraft so the KC-46A can be used in mixed-Service operations.

I wouldn't say its a non-issue. This tanker was bought to support all DOD aircraft not just USAF aircraft. So this is just as in important as the boom not working

But in the interim, you can fuel USAF aircraft off the boom and USN/USMC aircraft off the drogue. The only "loss" at the moment is with the WARPs the KC-46 can re-fuel two USN/USMC frames at the same time versus just one off the drogue.

kc135topboom wrote:

The KC-46 also has in internal centerline hose and drogue system. I have not heard if there are any issues with that system. Does anyone know anything?

That appears to have worked without issue.

Stitch wrote:

INFINITI329 wrote:

Stitch wrote:

Yes, but Boeing and Cobham PLC have refueled planes from the WARPs so they just need to deal with the flutter issue (which I believe is the problem). The USAF has said they expect the WARPs to be ready by next year (October 2018) which is fine considering I believe only USN / USMC aircraft use them so for normal USAF operations, it's a non-issue not having them equipped. And even then, the center drogue system can refuel USN / USMC aircraft so the KC-46A can be used in mixed-Service operations.

I wouldn't say its a non-issue. This tanker was bought to support all DOD aircraft not just USAF aircraft. So this is just as in important as the boom not working

But in the interim, you can fuel USAF aircraft off the boom and USN/USMC aircraft off the drogue. The only "loss" at the moment is with the WARPs the KC-46 can re-fuel two USN/USMC frames at the same time versus just one off the drogue.

kc135topboom wrote:

The KC-46 also has in internal centerline hose and drogue system. I have not heard if there are any issues with that system. Does anyone know anything?

That appears to have worked without issue.

The center line system has a higher dispense rate, some receiver aircraft have problems with that.

The wing mounted pods are part of the contract and clearly not ready when all frames should be delivered. The "little" flutter problem seems to need two additional years to be rectified, if no further delays happens.

mjoelnir wrote:

The center line system has a higher dispense rate, some receiver aircraft have problems with that.

The wing mounted pods are part of the contract and clearly not ready when all frames should be delivered. The "little" flutter problem seems to need two additional years to be rectified, if no further delays happens.

Well that is what flight testing is for.

I'm guessing it's something to do with Cobham's design itself since other 767 tankers (Italy and Columbia, at least) have WARPs and they don't appear to have flutter issues.

Stitch wrote:

mjoelnir wrote:

The center line system has a higher dispense rate, some receiver aircraft have problems with that.

The wing mounted pods are part of the contract and clearly not ready when all frames should be delivered. The "little" flutter problem seems to need two additional years to be rectified, if no further delays happens.

Well that is what flight testing is for.

I'm guessing it's something to do with Cobham's design itself since other 767 tankers (Italy and Columbia, at least) have WARPs and they don't appear to have flutter issues.

different engines, different flutter. The KC-767 uses GE and the KC46 uses P&W.

mjoelnir wrote:

different engines, different flutter. The KC-767 uses GE and the KC46 uses P&W.

So the issue is believed to be with the interaction between the pods and the engine nacelle?

mjoelnir wrote:

The "little" flutter problem seems to need two additional years to be rectified, if no further delays happens.

Two years for a fix? I'm seeing statements that the 19 tankers will be delivered within two years, not that it will take two years to resolve the flutter issues. Your posts seem to imply that the flutter problems cannot or will not ever be fixed. I find that to be highly unlikely.

Stitch wrote:

I'm guessing it's something to do with Cobham's design itself since other 767 tankers (Italy and Columbia, at least) have WARPs and they don't appear to have flutter issues.

The Italian tankers were seriously delayed because of flutter issues with their WARPs as well.

scbriml wrote:

The Italian tankers were seriously delayed because of flutter issues with their WARPs as well.

That's correct, it took over a year to solve the flutter issues at the Italian KC767's, powered by General Electric CF6-80C2 engines.

As already mentioned the KC-46A is powered by PW4062 engines, with a different installed weight and a different flow pattern around the engine pylons and cowlings

Additional problems may arise because the aircraft must be able to operate with and without the removable WARPS installed.

Computer simulation cannot predict all the interactions, so a lot of flight testing must be done to clear the entire flight envelope with and without Warps installed, with different aircraft weights and speeds. Also the fuel weight in each wing tank plays an important role.
If stiffening of the wing is needed at one point in the flight testing the whole proces has to be repeated again ............. because local wing stiffening can cause flutter issues at a seemingly unrelated other (wing)position.

11Bravo wrote:

Two years for a fix? I'm seeing statements that the 19 tankers will be delivered within two years, not that it will take two years to resolve the flutter issues.

The USAF have stated that they expect that by October 2018 the KC-46A fleet will have the pods, so they're budgeting for that long. Hopefully it won't be that long.

So now we know why it will take 2 years . . .

https://www.flightglobal.com/news/artic ... ix-428866/

If you change the aerodynamics, you gotta re-test.

bt

The article is not very clear and and raises even more questions.

- Wasn't the same problem already identified and solved at the Italian KC767 with WARPS ?

- What is different at the KC-46A WARPS, besides the powerplants, compared to the KC767 ?

I'm guessing the Cobham WARPS are of a different aerodynamic design than the Italian ones so they generate different aerodynamic forces.

Based on the article, the patent in question fixes the issue, but the FAA requires a certain number of flight hours to certify it and accumulating those hours with the testing assets available will take two years.

Stitch wrote:

I'm guessing the Cobham WARPS are of a different aerodynamic design than the Italian ones so they generate different aerodynamic forces.

Cobham supplies the KC-46A WARPS and the installed RP-910E-75 WARP's are based upon Cobham’s 5th generation 900E electric architecture (A330 MRTT, etc), the shape is optimized for KC-46A and the transfer rate is 400+ USgal/min.

See : http://www.cobham.com/mission-systems/a ... lling-pods

However the WARPS installed at the KC767A for the Italian airforce were provided by Smiths Aerospace (now : GE Aviation Systems), max transfer rate of 480 USgal/min.

See : http://www.businesswire.com/news/home/2 ... onstration

And : http://aviationphotodigest.com/aeronaut ... -italiana/

After selecting a new manufacturer for the KC-46A WARP's , Boeing is now facing the same WARP integration delays as with the KC-767A in 2007.
Staying with GE Aviation systems would have avoided a lot of issues and extra costs.

Patent application reveals KC-46 refueling pod fix

https://www.flightglobal.com/news/artic ... ix-428866/

It should have been a known fact that integrating WARP on the B767 poses problems. Comparing the KC-767A and the KC-46A has to take into account that they neither use the same engine nor the same wing as the other. It is therefor questionable if the KC-767A solution would have been usable on the KC-46A unchanged.

The result is that Boeing will have problems supplying KC-46A as ordered in the agreed time frame. They will be at least not fully functional.

mjoelnir wrote:

Patent application reveals KC-46 refueling pod fix

https://www.flightglobal.com/news/artic ... ix-428866/

The same article was posted in #255 above, i.e. four posts earlier.

mjoelnir wrote:

It should have been a known fact that integrating WARP on the B767 poses problems. Comparing the KC-767A and the KC-46A has to take into account that they neither use the same engine nor the same wing as the other. It is therefor questionable if the KC-767A solution would have been usable on the KC-46A unchanged.

The result is that Boeing will have problems supplying KC-46A as ordered in the agreed time frame. They will be at least not fully functional.

All true, and yet the DoD has still gone ahead and signed the $2.8B contract for the first 19 frames presumably knowing all of the above.

I suppose in theory that the DoD could voice their displeasure by never buying another KC-46 beyond these 19 frames, but I wouldn't count on that.

So, life goes on.

In the grand scheme of things, having to wait for another 2 years to have the pods ready for use is not a big deal. The Air Force would just have to schedule other assets when they are tasked to tank up Navy or Allies planes or make due with the center-line drogue. Going from 4 engines to 2 engines alone will save them lots of fuel that they will probably try to make max use of these planes once they are available.

bt

Revelation wrote:

All true, and yet the DoD has still gone ahead and signed the $2.8B contract for the first 19 frames presumably knowing all of the above.

Boeing may deliver several aircraft without operational WARP's.

KarelXWB wrote:

Revelation wrote:

All true, and yet the DoD has still gone ahead and signed the $2.8B contract for the first 19 frames presumably knowing all of the above.

Boeing may deliver several aircraft without operational WARP's.

True, and the FG article linked twice so far says:

The first 18 KC-46s are now going to be delivered by January 2018 with all the requirements except the WARPs, which will come in October of that year. While Boeing will equip the initial 18 aircraft with refueling boom and centerline drogue refueling capabilities, the WARPs fulfill the Air Force’s required assets available milestone.

I'm trying to figure out why this seems to be controversial.

It seems around post #242 ( viewtopic.php?f=10&t=1028475&start=200#p19043345 ) there was some controversy around calling the WARP problem a "non-issue". To me it seems like indeed it is a non-issue relative to Boeing's main concern, which was getting the LIRP contract signed so they would get paid for the first batch of frames. Getting that $2.8B contract signed would be my main concern if I had a program that has already taken almost $2B in write offs. And it also seems to be a non-issue to the USAF since as we read above the WARPs will meet the "required assets available milestone" whatever that is, and of course they did declare Milestone C to be completed so that the LIRP contract could be signed.

Also, the FG article says:

Boeing maintains that prolonged conformity and qualification testing needed for Federal Aviation Administration certification — and not a functionality issue — caused the pods to fall a year behind schedule.

“The patent is reflected in the baseline integrated design of the WARPs and was in place at first flight of the KC-46 (Sept 2015),” Boeing says in an email to FlightGlobal. “There is not a problem with the WARPs functionality … the WARP and center line drogue systems performed as planned during Milestone C testing.”

So, IMHO, the WARP situation is indeed a non-issue, based on what we are being told. Of course they could be lying, but the statements seem pretty direct.

mjoelnir wrote:

It should have been a known fact that integrating WARP on the B767 poses problems. Comparing the KC-767A and the KC-46A has to take into account that they neither use the same engine nor the same wing as the other. It is therefor questionable if the KC-767A solution would have been usable on the KC-46A unchanged.

I'm pretty sure the KC-46A uses a standard 767-200ER wing (earlier RFPs were based on the 767-300F and perhaps even 767-400ER wing).

Boeing would have done wind tunnel and CFD testing prior to first flight and felt they had a handle on it based on both, but that is why certification agencies require the OEMs to actually fly the plane because modeling is not always 100% accurate.