Max Q
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Highest Speed / Altitude For Air Refuelling?

Fri Jul 15, 2011 8:42 am

Curious to know what the highest speeds / mach no's and altitudes have been or are used for in flight refuelling.


I would guess the SR71 was the highest but what about other types and what sort of speeds and altitudes are used normally ?
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spudh
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RE: Highest Speed / Altitude For Air Refuelling?

Fri Jul 15, 2011 9:01 am

AFAIK air refueling is tailored to the individual lift charateristics of the aircraft being refueled.

The tanker itself is not the problem, they are optimised for a much higher cruising speed than some of the fighters they refuel.

IIRC in one of the Gulf Wars some of the USAF tankers had been given the wrong profile for the F14 and the the guys in fully loaded F14A's (which has quite a low cruise speed when it's wings are forward) were having to use afterburner to stay hooked up!! Not an efficient way to refuel.
A little bit of back room coordination and it was sorted by flying a different profile, although for some reason I recall they still preferred to refuel from RAF tankers than USAF, can't remember why though.

The SR-71 on the other hand, I believe was quite tricky to refuel as there was only a few knots airspeed between the cruise and stall at refuel altitude. It's been a while since I read Brian Shuls book 'The Untouchables' but IIRC this was around 30,000 feet.

I'm a bit hazy on all this so hopefully KC135 will be along shortly and he'll have all the first hand experience you could possibly want on all this.
 
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spudh
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RE: Highest Speed / Altitude For Air Refuelling?

Sun Jul 17, 2011 12:18 pm

I just checked 'The Untouchables', the normal refueling altitude for the SR-71 was 25,000 feet at which it would require one afterburner to be lit as the tanks neared full. Refueling at higher altitudes required both after burners.
In the Libya missions they refueled at 300 knots at 30,000 feet. Shul reports that this was just 10 knots above Vmin.
 
BladeLWS
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RE: Highest Speed / Altitude For Air Refuelling?

Mon Jul 18, 2011 12:36 am

Quoting spudh (Reply 1):
A little bit of back room coordination and it was sorted by flying a different profile, although for some reason I recall they still preferred to refuel from RAF tankers than USAF, can't remember why though.

If I had to guess I would think that it was because the KC-135 used an attachment to the end of the boom to refuel probe type aircraft, and the RAF tankers reeled out the drouge. The short hose on the -135 would be harder to hold in position then the longer one of the the VC-10s and L1011's.
 
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kc135topboom
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RE: Highest Speed / Altitude For Air Refuelling?

Tue Jul 19, 2011 3:38 pm

IIRC, refueling the SR-71A from the KC-135Q was done between FL-310 and FL-250 at 335 KIAS. If more speed was required the tanker would start a 'taboggan manuver' which was a decent during refueling. Many fighter aircraft refueled at between 305 KIAS and 330 KIAS. The FB-111A would refuel at FL-220 to FL-200 at 315 KIAS from the KC-135A/E/Q.

Keep in mind the KC-135A/Q were faster than the KC-135E/R/T. I believe the E/R/T has a max mach. number around .90M, while the A/Q had a max mach. number of .95M. For the KC-135A/Q at most refueling altitudes, .95M comes out around 355 KIAS.
 
windy95
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RE: Highest Speed / Altitude For Air Refuelling?

Tue Jul 19, 2011 7:41 pm

Quoting KC135TopBoom (Reply 4):
Many fighter aircraft refueled at between 305 KIAS and 330 KIAS. The FB-111A would refuel at FL-220 to FL-200 at 315 KIAS from the KC-135A/E/Q.

We used to run from Pease and drag the FB-111A's to Nellis and back. While the 111's hit the range we would drop in to McConnell or Offutt refuel get airborne and catch them for the round trip back. It was a long day.

Quoting KC135TopBoom (Reply 4):
Keep in mind the KC-135A/Q were faster than the KC-135E/R/T

The J-57 sucked on T/O but kept the A model rolling at altitude. The one thing I do not miss was dragging the A-10's across the Atlantic or Pacific..Adding multiple hours to the mission. Also refueling the C-130's by dropping flaps to get slow enough...
 
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Moose135
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RE: Highest Speed / Altitude For Air Refuelling?

Wed Jul 20, 2011 2:17 am

Quoting windy95 (Reply 5):
Also refueling the C-130's by dropping flaps to get slow enough...

Did a TDY to Eglin once and played with those guys for a week. How slow can you go...  
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kc135topboom
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RE: Highest Speed / Altitude For Air Refuelling?

Fri Jul 22, 2011 9:20 pm

Quoting windy95 (Reply 5):
windy95

When were you at Pease? I was there in 1978-1980 and again in 1985-1990. I was the "Wing Boom", and 509th AREFS First Sergent in 1986-1988 and the wing flight scheduler after that.

My name was painted on the "Wing Tanker", (then) KC-135A 62-3509 during that time, I believe she is an "R" model now stationed in the UK now. The "Wing Bomber" was FB-111A 69-6509,
 
windy95
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RE: Highest Speed / Altitude For Air Refuelling?

Mon Jul 25, 2011 5:13 pm

Quoting KC135TopBoom (Reply 7):
Quoting windy95 (Reply 5):
windy95

When were you at Pease? I was there in 1978-1980 and again in 1985-1990. I was the "Wing Boom", and 509th AREFS First Sergent in 1986-1988 and the wing flight scheduler after that.

My name was painted on the "Wing Tanker", (then) KC-135A 62-3509 during that time, I believe she is an "R" model now stationed in the UK now. The "Wing Bomber" was FB-111A 69-6509,

I was there from 1985 to 1990...62-3509 was "the Spirit of the Seacoast". I crewed 3502, 3633 and lastly 2599.
 
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kc135topboom
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RE: Highest Speed / Altitude For Air Refuelling?

Mon Jul 25, 2011 10:39 pm

There were two Booms used on the KC-135A, the "High Speed Boom" which was rated and approved to refuel up to 355 KIAS, or .95M, the max allowed airspeed of the tanker. The "Low Speed Boom" was rated at 315 KIAS, but all of them were eventually converted to High Speed Booms.

All Booms had high speed ruddervators after 1972. The 'canoe' atop the boom, which hosed the cable attachment and the ring for the hook to stow it was shorter on the low speed boom. Most, but not all high speed booms also had a boundrey layer wrapped around the boom at the longer 'canoe'.

Low speed booms were installed on the first 300, or so, KC-135As and high speed booms on all remaining 432 KC-135As, The booms were interchangeable. They could be changed out at the base level, and were always removed at depot. So any boom could be on any KC-135A. All of the KC-135Qs only had high speed booms.
 
Max Q
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RE: Highest Speed / Altitude For Air Refuelling?

Tue Jul 26, 2011 4:46 am

Thanks Top Boom, always enjoy your posts. I did not realise the KC135 was that fast, that is impressive. .95 Mach is the fastest MMO I have heard of on any subsonic, transport Aircraft !


Apart from the SR71, what was the Aircraft with, routinely the fastest refueling speed you worked with ?

[Edited 2011-07-25 21:47:46]
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harleydriver
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RE: Highest Speed / Altitude For Air Refuelling?

Tue Jul 26, 2011 11:40 pm

I was a boom up with the MAINEiacs from '96 to '00 then at McGuire from '00 to '03. I took a severe downgrade to become a loadmaster and now doing the load thing but I REALLY miss being a boom! Loved that job!!!

The reason probe equipped receivers preferred the drogue from the KC-10, RAF L-1011 or the VC-10 was the soft basket. The basket on the -135 was solid and bounced off the receiver fairly hard as they were making contact where the soft basket would just softly brush up against their aircraft as they are making contact. The one advantage to the -135 hose and drogue was the shorter hose and less whipping where the longer hose of the centerline drogue on the KC-10 tended to move around more in turbulence. I got this info from an F-14 pilot many years ago after dragging them across the pond and having beers at Rota, Spain as an en route stop on their way to Sigonella. I did lose a basket once on a Red Flag mission refueling F-18's. It was determined there was corrosion where the basket connected to the hose and the basket stayed on the F-18. We heard it stayed with the F-18 all the way until landing. The basket is part of the hose aerodynamics and we did get some whipping around of the hose but nothing that came close to hitting our jet.

The fastest A/R I have done was just your standard F-15 and F-16 refuelings at 315 KIAS typically around FL280 to maybe FL330 for training and higher for drags across the ocean, maybe FL350. I remember we had a couple of low speed booms up in Bangor and the overrun speed of 335 KIAS when refueling fighters came into play. The low speed of the boom didn't into play at cruise, only when the boom was lowered for A/R. I never refueled the F-111, just watched it when I was a crew chief before being a boom so I couldn't tell you that A/R seed and although I refueled German F-4's once, I don't remember that A/R airspeed.

The fastest I ever saw at cruise in an E Model was M.86 and I know we were close to barber pole on the airspeed indicator. We were behind for a HHQ mission and pushed it up. Now TACC is closely following fuel burns and you need TACC permission to go with anything higher then the scheduled fuel load and the Aircraft Commanders name is high lighted if more fuel then minimum necessary is added to the mission so no more pushing it up if you need to offload a certain amount of fuel as a minimum and I hear it's not uncommon for receivers to ask for a bit of extra fuel and the tanker crew being unable as TACC allowed only the minimum for the mission scheduled.
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HaveBlue
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RE: Highest Speed / Altitude For Air Refuelling?

Wed Jul 27, 2011 12:32 am

Quoting HarleyDriver (Reply 11):
Now TACC is closely following fuel burns and you need TACC permission to go with anything higher then the scheduled fuel load and the Aircraft Commanders name is high lighted if more fuel then minimum necessary is added to the mission so no more pushing it up if you need to offload a certain amount of fuel as a minimum and I hear it's not uncommon for receivers to ask for a bit of extra fuel and the tanker crew being unable as TACC allowed only the minimum for the mission scheduled

That is crazy, especially the very last part. Interesting.
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spudh
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RE: Highest Speed / Altitude For Air Refuelling?

Wed Jul 27, 2011 9:43 am

Quoting HarleyDriver (Reply 11):
I did lose a basket once on a Red Flag mission refueling F-18's. It was determined there was corrosion where the basket connected to the hose and the basket stayed on the F-18. We heard it stayed with the F-18 all the way until landing. The basket is part of the hose aerodynamics and we did get some whipping around of the hose but nothing that came close to hitting our jet.

I'm pretty sure I've seen a photo of that F18 coming in to trap with the basket hanging off it somewhere!!!
Can't remember if it was on here or in one of my books at home. Must go check.

Excellent story though  
 
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spudh
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RE: Highest Speed / Altitude For Air Refuelling?

Thu Jul 28, 2011 5:54 pm

Quoting HarleyDriver (Reply 11):
I did lose a basket once on a Red Flag mission refueling F-18's. It was determined there was corrosion where the basket connected to the hose and the basket stayed on the F-18. We heard it stayed with the F-18 all the way until landing.

Couldn't find the F18 but I did find this  
 
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Moose135
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RE: Highest Speed / Altitude For Air Refuelling?

Thu Jul 28, 2011 6:41 pm

Was talking with a friend who worked on KC-135s and B-52s back in the 1960s and '70s. He remembered losing at least one basket to a Navy fighter, and also told me about the day he was on the flight line (somewhere down south) when a "unicorn" B-52 came in. He didn't remember how it happened, but the boom got punched through the forward fuselage, in the cockpit area, of the B-52, and broke off the tanker. The BUFF returned to base with the boom sticking out the top of the fuselage. They stopped and shut down on the runway - one of the navigators, flight suit soaked with fuel, was out of the airplane almost before it stopped, diving into the drainage ditch alongside the runway, pulling off his flight suit as he went.
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cpd
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RE: Highest Speed / Altitude For Air Refuelling?

Fri Jul 29, 2011 1:51 am

Quoting spudh (Reply 1):
The SR-71 on the other hand, I believe was quite tricky to refuel as there was only a few knots airspeed between the cruise and stall at refuel altitude. It's been a while since I read Brian Shuls book 'The Untouchables' but IIRC this was around 30,000 feet.

He also recalls the trick used when the SR-71 got quite heavy near the end and they'd use the reheat on one engine for the last bit of the refuel. You can imagine how tricky that would have been.
 
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kc135topboom
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RE: Highest Speed / Altitude For Air Refuelling?

Fri Jul 29, 2011 11:25 pm

Quoting Max Q (Reply 10):
Apart from the SR71, what was the Aircraft with, routinely the fastest refueling speed you worked with ?


Most fighter sized, including the FB-111, aircraft boom refueled at 315 KIAS. It was different with USN or USMC aircraft as you had to use NAVTOPS manuals for speeds. altitudes, etc. NAVTOPS was really written with the KA-3s and KA-6s in mind, not the faster KC-135.

I can recall draging the 49 FIS (we called them the 49 MACS for mid air collision squadron) to Iceland from their hame base at RME and they wanted to refuel at 325 KIAS, but the 'standard' refuel speed was 315 KIAS. On an ORI where the FB-111As were running very late we refueled them at 335 KIAS, they were also normally refueled at 315 KIAS. They made their TOT times good. Word got back to the Wing King, and he wasn't happy when we landed as he thought we broke the peacetime flying rules, thus cost him the ORI because thos bombers and our refueling would not be scored. We told him there was no such restriction, but he didn't believe us until the SAC-IG himself stepped in and congradulated us for the "innovated" and "fully mission oriented" attitude my crew had in helping to get the FBs to their targets "on-time" When the bomber crews landed he congradulated them, too. The Wing King changed his attitude and gave us a written "well-done", along with buying is a drink at the Officer's Club.

Quoting cpd (Reply 16):
when the SR-71 got quite heavy near the end and they'd use the reheat on one engine for the last bit of the refuel. You can imagine how tricky that would have been.

Actually I had many receivers light a burner during refueling as they got heavier, not just the SR-71. F/EF/ FB-111s, F/RF-4s, F-105s, F-106s, etc. did that a lot, too. It actually stabilized them a lot. They only went to min. burner on one engine, in the daytime you couldn't see it, but you could see it at night. The F/RF-4C was doing that on almost every refueling I had with them as they had the lower thrust engines compared to the F-4D/E/F/G.

In contrast, most heavies like the B-52, EC/RC/KC-135, C-5, etc refueled between 255 and 275 KIAS.

Of course there are exceptions to both the fighter sized and heavies refueling speeds, the A-10 refueled at 205 KIAS and slower and the EC/AC/MC/C-130s refueled as slow as 180 KIAS (AC-130 because of all the drag they had).
 
Max Q
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RE: Highest Speed / Altitude For Air Refuelling?

Sat Jul 30, 2011 4:23 am

Thanks TopBoom,



I would imagine they would have to put some flap out at the lower speeds ?
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kc135topboom
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RE: Highest Speed / Altitude For Air Refuelling?

Sat Jul 30, 2011 12:33 pm

Yes, for refueling the C-130s we had to set the flaps to 20, IIRC.

Quoting KC135TopBoom (Reply 17):
I can recall draging the 49 FIS (we called them the 49 MACS for mid air collision squadron) to Iceland from their hame base at RME and they wanted to refuel at 325 KIAS, but the 'standard' refuel speed was 315 KIAS.

I forgot to mention these aircraft were F-106A/Bs.

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