Sponsor Message:
Military Aviation & Space Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
In Flight Refuelling Question  
User currently offlineMax Q From United States of America, joined May 2001, 4071 posts, RR: 19
Posted (8 months 3 weeks 3 days 17 hours ago) and read 6176 times:

Can Military Aircraft be refuelled in flight to a higher maximum weight than allowed for take off ?


The best contribution to safety is a competent Pilot.
26 replies: All unread, showing first 25:
 
User currently offlinemoo From Falkland Islands, joined May 2007, 3829 posts, RR: 5
Reply 1, posted (8 months 3 weeks 3 days 12 hours ago) and read 6091 times:

Yes, it happens all the time with the B-52 et al.

User currently offlinenomadd22 From United States of America, joined Feb 2008, 1764 posts, RR: 0
Reply 2, posted (8 months 3 weeks 3 days 11 hours ago) and read 6085 times:

Takeoff weights are often restricted by runway length and other factors. Refueling right after takeoff lets you operate from bases that couldn't handle MTOW ops.
I'm not familiar with 52s. Can they operate at higher weight than they can take off at from any runway, or would they just need a three mile long runway at maximum?



Andy Goetsch
User currently offlinestudedave From United States of America, joined Oct 2006, 465 posts, RR: 0
Reply 3, posted (8 months 3 weeks 3 days 3 hours ago) and read 5882 times:

I have seen this not only with B-52s, but also with jets (mostly F/A-18s) off of aircraft carriers.
It's one reason I think that 'replacing' the A-6 with lawn darts was a bad idea...
With the Intruder you could carry a lot of everything.
With the Hornet you carry fuel or the stuff that goes boom.
You don't get both. (and Hornets like fuel)





StudeDave



Classic planes, Classic trains, and Studebakers~~ what else is there???
User currently onlinelegs From Australia, joined Jun 2006, 230 posts, RR: 0
Reply 4, posted (8 months 3 weeks 3 days 2 hours ago) and read 5853 times:

Quoting moo (Reply 1):
Quoting studedave (Reply 3):

Are any of those cases actually refueling up above the MTOW of the airframe, or are they just trading payload and runway performance for fuel on board, knowing there's a tanker waiting?

[Edited 2013-07-29 14:12:40]

User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12061 posts, RR: 52
Reply 5, posted (8 months 3 weeks 3 days 1 hour ago) and read 5821 times:

Almost all airplanes have a high max gross weight than their MTOW would indicate.

In the case of the B-52G/H, they had a MTOW of 488,000 lbs., but could refuel up to a max weight of about 520,000 lbs. inflight. However refueling beyond 488K did reduce the B-52's maneuverability to about 1.7g. It then had to burn down the extra fuel to 488K to get back to a 2.5g.

Other airplanes like the EC/RC/KC-135, KC-10, E-3, E-6, E-8, C-141, C-5, and C-130s would also refuel beyond MTOW if their mission requirements dictated that..


User currently offlineMax Q From United States of America, joined May 2001, 4071 posts, RR: 19
Reply 6, posted (8 months 3 weeks 2 days 18 hours ago) and read 5700 times:

Quoting legs (Reply 4):

Are any of those cases actually refueling up above the MTOW of the airframe, or are they just trading payload and runway performance for fuel on board, knowing there's a tanker waiting?

That's the question I meant to ask !

Quoting KC135TopBoom (Reply 5):


In the case of the B-52G/H, they had a MTOW of 488,000 lbs., but could refuel up to a max weight of about 520,000 lbs. inflight. However refueling beyond 488K did reduce the B-52's maneuverability to about 1.7g. It then had to burn down the extra fuel to 488K to get back to a 2.5g.

Other airplanes like the EC/RC/KC-135, KC-10, E-3, E-6, E-8, C-141, C-5, and C-130s would also refuel beyond MTOW if their mission requirements dictated that..

Thanks KC, how much above MTOW could they go ?



The best contribution to safety is a competent Pilot.
User currently offlineGST From United Kingdom, joined Jun 2008, 930 posts, RR: 0
Reply 7, posted (8 months 3 weeks 2 days 16 hours ago) and read 5686 times:

Quoting KC135TopBoom (Reply 5):

Other airplanes like the EC/RC/KC-135, KC-10, E-3, E-6, E-8, C-141, C-5, and C-130s would also refuel beyond MTOW if their mission requirements dictated that..

Does anyone know if any of those aircraft are unable to dump fuel? It would be an odd situation for MLW to exceed MTOW, and some emergencies won't let you loiter to burn fuel.


User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12061 posts, RR: 52
Reply 8, posted (8 months 3 weeks 2 days 9 hours ago) and read 5573 times:

Quoting Max Q (Reply 6):
Thanks KC, how much above MTOW could they go ?

It depended on the airplane type, but generally between about 5% and 8%.

Quoting GST (Reply 7):
Does anyone know if any of those aircraft are unable to dump fuel? It would be an odd situation for MLW to exceed MTOW, and some emergencies won't let you loiter to burn fuel.

Most of those airplanes I listed can dump fuel if need be. I know all of the Boeings, except the B-52 can dump fuel. I am not sure about any of the Lockheed types. The KC-10 can also dump fuel.


User currently offlinerfields5421 From United States of America, joined Jul 2007, 7345 posts, RR: 32
Reply 9, posted (8 months 3 weeks 2 days 8 hours ago) and read 5554 times:

Back in 1972 when I was stationd at NAS Agana Guam, some guys renting the house next door to ours were B-52 crew members.

The aircraft for Linebacker and Linebacker II took off from Andersen at MTOW with the largest possible bomb load, and less fuel due to the weight of the ordnance load.

They tanked soon after takeoff for the maximum fuel possible as they had to make a 5,000 nm round trip. They also had to tank at least once more, possible twice - to complete the mission.

Should an aircraft tanked above MLW have to return to Andersen quickly, they would have dropped the bomb load over the ocean to get the aircraft weight lower.


User currently offlineptrjong From Netherlands, joined Mar 2005, 3884 posts, RR: 19
Reply 10, posted (8 months 3 weeks 2 days 8 hours ago) and read 5551 times:

Quoting KC135TopBoom (Reply 8):
It depended on the airplane type, but generally between about 5% and 8%.

Because there's just no room for cago and fuel left, or because the aircraft can't safely do any manoeuvring any more? Are there maximum gross weights for aircraft in the air? And overload weights maybe for special missions (the Vulcan raids)?



The only difference between me and a madman is that I am not mad (Salvador Dali)
User currently offlinenomadd22 From United States of America, joined Feb 2008, 1764 posts, RR: 0
Reply 11, posted (8 months 3 weeks 2 days 3 hours ago) and read 5449 times:

I've heard so many stories of the reason SR-71s always refueled after takeoff, I'm not sure which are true. Leaky tanks until the skin warmed up, wanting to takeoff and get up at lower weight, inefficient takeoff and climb, lower GTOW than gross operational or a combination of all of them. I think they usually took about 5,000 lbs right after takeoff.


Andy Goetsch
User currently offlinerc135x From , joined Dec 1969, posts, RR:
Reply 12, posted (8 months 3 weeks 1 day 20 hours ago) and read 5359 times:

Quoting KC135TopBoom (Reply 5):
Other airplanes like the EC/RC/KC-135, KC-10, E-3, E-6, E-8, C-141, C-5, and C-130s would also refuel beyond MTOW if their mission requirements dictated that..

The prototype KC-135E 59-1514 and KC-135R 61-0293 were both equipped for receiver air refueling from prior configurations. This allowed them to refuel during flight testing to absolute max gross weight which was well in excess of max gross takeoff weight (MGTOW). Age and amnesia have affected my ability to recall the specific numbers.

MGTOW was a function of engine capability rather than airframe fuel capacity. IIRC, the KC-135A "steam jet" was around 297k but the KC-135R was up around 322.5k. TopBoom be sure to check my weight & balance sheet!

In the TF33-equipped RC-135S we would takeoff at 285,000 MGTOW but after air refueling would be at 310,000, which was still below the in-flight max. There was little need to go to in-flight max and the stress it placed on the airframe as TopBoom mentioned with the B-52.

Quoting rfields5421 (Reply 9):
Should an aircraft tanked above MLW have to return to Andersen quickly, they would have dropped the bomb load over the ocean to get the aircraft weight lower.

This was not always the case. My dad aborted a B-52D mission out of Guam and they burned fuel to reach max gross landing weight while retaining the weapons load. Just prior to landing my dad announced over the intercom "Don't worry if any bombs fall off during the landing---they will explode under the tail and we'll be just fine." Silence. After landing the gunner finally spoke: "Thanks, pilot."  


User currently offlinesolarflyer22 From US Minor Outlying Islands, joined Nov 2009, 817 posts, RR: 3
Reply 13, posted (8 months 3 weeks 1 day 19 hours ago) and read 5342 times:

Quoting studedave (Reply 3):
With the Intruder you could carry a lot of everything.
With the Hornet you carry fuel or the stuff that goes boom.
You don't get both. (and Hornets like fuel)

Yeah, I've heard similar from a friend when they retired the Tomcats which had great range by comparison.

Quoting ptrjong (Reply 10):
or because the aircraft can't safely do any manoeuvring any more?

Yes, its already down to 1.7 G which means you can barely turn. Plus it stresses the wings and frame. You could hit turbulence for example above MTOW and no one is looking to fall apart.

Quoting nomadd22 (Reply 11):

I've heard so many stories of the reason SR-71s always refueled after takeoff, I'm not sure which are true. Leaky tanks until the skin warmed up, wanting to takeoff and get up at lower weight, inefficient takeoff and climb, lower GTOW than gross operational or a combination of all of them

My SR71 tour guide said it was leakage from the tanks that required tanking but they also flew very long missions as well.


User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12061 posts, RR: 52
Reply 14, posted (8 months 3 weeks 1 day 7 hours ago) and read 5199 times:

Quoting ptrjong (Reply 10):
Quoting ptrjong (Reply 10):
Quoting KC135TopBoom (Reply 8):It depended on the airplane type, but generally between about 5% and 8%.
Because there's just no room for cago and fuel left, or because the aircraft can't safely do any manoeuvring any more? Are there maximum gross weights for aircraft in the air? And overload weights maybe for special missions (the Vulcan raids)?

In the case of the B-52, it was because it was refueled to 'full tanks'. But flying it at just a 1.7g restriction really limited the ability to defend itself, to.

IIRC, the only times this was authorized for the B-52 was for test flights and for EWO/SIOP. The position on the attack route was critical for this weight. The bomber had to cross the HHCL (Higher Headquarters Control Line, or more commoningly know as the 'Fail Safe' point) at the max inflight weight. This gave them time to burn down to a more maneuverable weight before penetration.

In the case of the FB-111 on an EWO/SIOP mission, the long tanker would refuel them well past the HHCL. This put the tanker at great risk, but it extended the range of the FB-111 to have an adequate fuel reserve over the recovery base. The FB-111 would also burn then shed its external fuel drop tanks, then use its external weapons first (as did the B-52) to decrease drag, thus save additional fuel.

I cannot go into additional information about the SIOP missions.

The Avro Vulcan B2 version was also capable of refueling above the MTOW.


User currently offlineaklrno From United States of America, joined Dec 2010, 871 posts, RR: 0
Reply 15, posted (8 months 3 weeks 1 day ago) and read 5105 times:

Quoting solarflyer22 (Reply 13):
My SR71 tour guide said it was leakage from the tanks that required tanking but they also flew very long missions as well.

I was at the official retirement ceremony at Beale AFB some years back. They flew one ceremonial mission and then parked the plane by the grandstand set up for speeches. As the generals droned on the plane cooled, and started to leak. By the end of the speeches it was raining fuel at an astonishing rate. IIRC they used a special low volatility fuel to avoid fires at the beginning or end of a mission. I suspect that if Beale is ever abandoned by DoD the toxic chemical cleanup bill will be astronomical due to years of spilled fuel.


User currently onlineflyingturtle From Switzerland, joined Oct 2011, 2038 posts, RR: 13
Reply 16, posted (8 months 3 weeks 1 day ago) and read 5084 times:

OT:

When we are talking refuelling and the KC-135 - has the NTSB, the USAF or a Kyrgyz investigation board already issued an interim report about the KC-135 crash in Kyrgyztan??


David



Keeping calm is terrorism against those who want to live in fear.
User currently offlinewindy95 From United States of America, joined Dec 2008, 2690 posts, RR: 8
Reply 17, posted (8 months 3 weeks 8 hours ago) and read 4947 times:

Quoting flyingturtle (Reply 16):
the USAF or a Kyrgyz investigation board already issued an interim report about the KC-135 crash in Kyrgyztan??

Yes they briefed the CINC about a month ago and have released it to the safety depts but have not released the full one to the public yet. I heard it focuses on the -3 flight control section saying to review before flight. I think they are pointing at pilot error with Rudder deflection.

Quoting ptrjong (Reply 10):
Because there's just no room for cago and fuel left,

Yes limited by actual fuel tank size.



There had been missions out of places like Guam when we would do MITO departures and as soon as we had been airborne we (the KC-135) would accelerate ahead of the Buff's. At which point the boom would go to work and we would give them fuel on climbout. We would dump around 125,000lbs of fuel and peel off and head back home and land. Mission time for us would be around an hour and we would go from 285K in weight down to avout 130 to 140K just like that.



OMG-Obama Must Go
User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12061 posts, RR: 52
Reply 18, posted (8 months 2 weeks 5 days 1 hour ago) and read 4626 times:

Quoting windy95 (Reply 17):
There had been missions out of places like Guam when we would do MITO departures and as soon as we had been airborne we (the KC-135) would accelerate ahead of the Buff's. At which point the boom would go to work and we would give them fuel on climbout. We would dump around 125,000lbs of fuel and peel off and head back home and land. Mission time for us would be around an hour and we would go from 285K in weight down to avout 130 to 140K just like that.

I never got a chance to fly one of those missions.


User currently offlinemoo From Falkland Islands, joined May 2007, 3829 posts, RR: 5
Reply 19, posted (8 months 2 weeks 4 days 6 hours ago) and read 4445 times:

Quoting nomadd22 (Reply 11):

Col Richard Graham, an Sr-71 pilot, explains it fairly well in his book - while it was indeed leaky as a sieve, it wasn't the reason for it tanking soon after take off.

Infact, it used to fly a lot of missions from Kadena with full tanks without tanking.

The reason it used to tank on a lot of missions was because the single engine performance was so poor it was deemed to be too dangerous for missions where a tanker could be used.


User currently offlineawacsooner From United States of America, joined Jan 2008, 1800 posts, RR: 1
Reply 20, posted (8 months 2 weeks 2 days 12 hours ago) and read 4062 times:

We do it all the time in the E-3...since we have those awesome JT3 (TF33) engines  

User currently offline10boomer From United States of America, joined Dec 2005, 57 posts, RR: 5
Reply 21, posted (8 months 6 days ago) and read 3399 times:

Quoting KC135TopBoom (Reply 5):
Other airplanes like the EC/RC/KC-135, KC-10, E-3, E-6, E-8, C-141, C-5, and C-130s would also refuel beyond MTOW if their mission requirements dictated that..

Both the MTOW and In-Flight Gross Weight for the KC-10 is 590,000



Fly Gucci
User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12061 posts, RR: 52
Reply 22, posted (8 months 5 days 4 hours ago) and read 3288 times:

Quoting 10boomer (Reply 21):
Quoting KC135TopBoom (Reply 5):Other airplanes like the EC/RC/KC-135, KC-10, E-3, E-6, E-8, C-141, C-5, and C-130s would also refuel beyond MTOW if their mission requirements dictated that..
Both the MTOW and In-Flight Gross Weight for the KC-10 is 590,000

Is that a change? Back in the 1980s, IIRC, we would refuel the Gucci Bird to 615K or 625K, I cannot remember which one. When they were loaded with cargo, we would fill them to full tanks.


User currently offlineconnies4ever From Canada, joined Feb 2006, 4066 posts, RR: 13
Reply 23, posted (8 months 5 days 3 hours ago) and read 3276 times:

Quoting aklrno (Reply 15):
I was at the official retirement ceremony at Beale AFB some years back. They flew one ceremonial mission and then parked the plane by the grandstand set up for speeches. As the generals droned on the plane cooled, and started to leak. By the end of the speeches it was raining fuel at an astonishing rate. IIRC they used a special low volatility fuel to avoid fires at the beginning or end of a mission. I suspect that if Beale is ever abandoned by DoD the toxic chemical cleanup bill will be astronomical due to years of spilled fuel.


The low volatility fuel was designated JP-7 and required a chemical additive (I think triethylborane but I might be wrong) to get it to ignite. Apparently you could toss a lit cigarette into the JP-7 with impunity. I believe a dedicated subfleet of tanker, KC-135Qs, were tasked with supporting the A-12/SR-71 fleet.



Nostalgia isn't what it used to be.
User currently offlinewindy95 From United States of America, joined Dec 2008, 2690 posts, RR: 8
Reply 24, posted (8 months 4 days 9 hours ago) and read 3146 times:

Quoting connies4ever (Reply 23):
I believe a dedicated subfleet of tanker, KC-135Qs, were tasked with supporting the A-12/SR-71 fleet.

Correct. The Q had two refueling manifolds. One for the JP-7 for the body tanks and one for the JP-4 and the wing tanks. They had been based at Beale and then overseas at Okinawa and Mildenhall.



OMG-Obama Must Go
25 10boomer : As long as I've been with the 10 (1992-) that's been the limitation. The max in-flight weight is actually a Warning.
26 connies4ever : Not my post, was TopBoom's.
Top Of Page
Forum Index

Reply To This Topic In Flight Refuelling Question
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Military aviation related posts only!
  • Not military related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
RAF C17 In-flight Refuelling posted Mon Jul 19 2004 20:08:56 by Splitzer
A-4 Fuel Tank Desintegrates In-Flight *Video* posted Thu Jun 23 2011 09:07:21 by FlexJetOKC
Reddit: I Refuel Airplanes In Flight, AMA posted Fri Sep 3 2010 15:04:55 by TGIF
Air Force One In Flight posted Thu Mar 11 2010 05:23:38 by originalblis
Interesting Story/movie On In Flight Refueling posted Sun Apr 20 2008 09:55:38 by Kchs29418
If You Were In Flight School You'd Want To Fly.... posted Sat Oct 20 2007 15:32:28 by KevinSmith
F-35 In-Flight Problem posted Sat May 12 2007 00:06:49 by Connies4ever
Airborne Laser To Test-fire In Flight posted Mon Jan 29 2007 22:44:44 by JakeOrion
U-2 Flight Profile Question posted Mon Oct 2 2006 02:03:38 by Bhill
Any Usaf In-Flight Refuelers In Here? posted Wed Sep 15 2004 08:57:32 by Delta767300ER

Sponsor Message:
Printer friendly format