USAF change AAR
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USAF change AAR
Does anyone know just WHY the USAF went from "Probe and Drogue" on their Fighters [Multiple IFRs] to the Boom method.... single IFR. To accommodate the Bomber Fleet perhaps?
But with a proven multipoint IFR in use, why change it?
But with a proven multipoint IFR in use, why change it?
The flying boom provides a higher fuel transfer rate than probe and drogue and the KC-135 was originally intended to support primarily the B-47 and B-52 fleets. By the time the B-47 was withdrawn, the ratio of KC-135 to B-52 was around 1:1. Presumably, the USAF decided at the time that it only wanted one system and therefore the flying boom system was specified for fighters. Since then, some KC-135s have been fitted with Flight Refuelling Ltd Mk 32b pods as well and a probe and drogue adaptor can be fitted to the flying boom to support USN, USMC and other nation missions.
The first operational use of AAR in the USAF was by F84s in the Korean War. It was required as the Allies were pushed south and airfields overrun by the communists which meant many sorties had to be flown from Japan. The F84 had two probe mounted on the front of two tip tanks. As you can imagine, making contact was difficult with such an arrangement and required two contacts. This made it very slow and the Generals in charge wanted a better system which led Boeing to develope the flying boom system. For a while, both boom and probe and drogue systems were in use ( with the probes being more intelligently minted on the centreline) but it appears the boom was more popular.
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The KC-135 was originally bought in 1954 as an "Interim buy" pending the completion of the tanker competition (the Lockheed CL-131 "won" over the KC-135 in February 1955, but the CL-131 was just a paper design at that point, while the KC-135 had a flying prototype).
As the urgent need was for bomber refueling (due to the quantities of fuel needed), the boom only was fitted to save money.
In the end, the CL-131 was canceled and the KC-135 was ordered in quantity - still with only the boom.
Some back-history:
The old USAF system, in use with bombers before 1950, was the "looped hose" system, where the receiver was ahead of the tanker, paid out a static line to the tanker which was then used to pull the hose forward to the receiver aircraft.
In Feb 1952 the USAF fitted a B-36H with the USAF LH system for tests with a B-47 (as receiver), with the tests being done in May 1952. In January 1953 "a new and vastly improved British made probe and drogue refueling system was installed".
The USAF had, in 1950, begun using the British "probe & drogue" system for fighters, but the probe was on a drop tank, not the fighter itself, and only a few of the USAF's tankers were fitted with "drogue hose" reels.
Also in 1950 the USAF had begun using the "flying boom" to refuel bombers, and since all tankers were part of the Strategic Air Command (along with the bombers), the bomber method was chosen as the sole system to be installed in the new USAF tankers (and thus, in all new USAF aircraft).
As the urgent need was for bomber refueling (due to the quantities of fuel needed), the boom only was fitted to save money.
In the end, the CL-131 was canceled and the KC-135 was ordered in quantity - still with only the boom.
Some back-history:
The old USAF system, in use with bombers before 1950, was the "looped hose" system, where the receiver was ahead of the tanker, paid out a static line to the tanker which was then used to pull the hose forward to the receiver aircraft.
In Feb 1952 the USAF fitted a B-36H with the USAF LH system for tests with a B-47 (as receiver), with the tests being done in May 1952. In January 1953 "a new and vastly improved British made probe and drogue refueling system was installed".
The USAF had, in 1950, begun using the British "probe & drogue" system for fighters, but the probe was on a drop tank, not the fighter itself, and only a few of the USAF's tankers were fitted with "drogue hose" reels.
Also in 1950 the USAF had begun using the "flying boom" to refuel bombers, and since all tankers were part of the Strategic Air Command (along with the bombers), the bomber method was chosen as the sole system to be installed in the new USAF tankers (and thus, in all new USAF aircraft).
FYI
The soon to fly Boeing 767-2C/KC-46 will have both center boom and wing mounted probe and drogue. At least in theory it'll be capable of fueling 3 aircraft at the same time.
BTW, it's my understanding that the center-line boom is far easier on the pilots due to the lack of wingtip vortex that tends to throw the to-be-refueled airplane for a loop (almost literally).
The soon to fly Boeing 767-2C/KC-46 will have both center boom and wing mounted probe and drogue. At least in theory it'll be capable of fueling 3 aircraft at the same time.
BTW, it's my understanding that the center-line boom is far easier on the pilots due to the lack of wingtip vortex that tends to throw the to-be-refueled airplane for a loop (almost literally).
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The KC-10s the USAF has been flying since 1980 have both the centerline under-tail boom and a single drogue and hose system on the starboard side of the rear fuselage.
Here is more info on the CL-131: http://forum.keypublishing.com/showt...er-Competition
Here is more info on the CL-131: http://forum.keypublishing.com/showt...er-Competition
Very difficult.
Much easier.
Both have their advantages and disadvantages. The boom system has much quicker connect times and the transfer rate is faster. However, once it contact, the receiver pilot has to work harder to stay in position due to a more limited range of formation position. Also, it requires an extra tanker crew member and the boom is large and heavy which requires it to be fitted to large aircraft only. Buddy/buddy tanking is not feasible - which is the main reason the USN stuck with the probe and drogue. You can't fit large aircraft on carriers! And the big limitation is that you can only refuel one receiver at a time.
Probe and drogue is harder to connect, but easier once in contact. Flow rates are less, but this is usually only a problem for larger aircraft as the hose can often transfer faster than a lot of fighters can take it. You can refuel multiple receivers. Also, with more operators using P and D, there is much more planning flexibility with allies being able to refuel each other's aircraft.
Much easier.
Both have their advantages and disadvantages. The boom system has much quicker connect times and the transfer rate is faster. However, once it contact, the receiver pilot has to work harder to stay in position due to a more limited range of formation position. Also, it requires an extra tanker crew member and the boom is large and heavy which requires it to be fitted to large aircraft only. Buddy/buddy tanking is not feasible - which is the main reason the USN stuck with the probe and drogue. You can't fit large aircraft on carriers! And the big limitation is that you can only refuel one receiver at a time.
Probe and drogue is harder to connect, but easier once in contact. Flow rates are less, but this is usually only a problem for larger aircraft as the hose can often transfer faster than a lot of fighters can take it. You can refuel multiple receivers. Also, with more operators using P and D, there is much more planning flexibility with allies being able to refuel each other's aircraft.
Dan
Not convinced about the relative nos of P and D vs boom which will probably change with the type of act chosen to replace F16 anyway; not only that but flexibility and planning in a NATO or coalition mission are infrequent partners.On the last regime change effort in 2011 we even had P and D rx unable to take fuel from certain P and D tankers (and I don't mean the BDA either) . The only way to have true flexibility is to have both systems on the same tanker -pity we got that one wrong with Voyager, it is also a pity the RAF has a tanker that can't refuel one of its own rx!
Not convinced about the relative nos of P and D vs boom which will probably change with the type of act chosen to replace F16 anyway; not only that but flexibility and planning in a NATO or coalition mission are infrequent partners.On the last regime change effort in 2011 we even had P and D rx unable to take fuel from certain P and D tankers (and I don't mean the BDA either) . The only way to have true flexibility is to have both systems on the same tanker -pity we got that one wrong with Voyager, it is also a pity the RAF has a tanker that can't refuel one of its own rx!
The soon to fly Boeing 767-2C/KC-46 will have both center boom and wing mounted probe and drogue. At least in theory it'll be capable of fueling 3 aircraft at the same time.
Thats always been theoretically posible with 3 point tankers, but would involve some pretty scary formation flying. I'm wondering if it has ever been done, if only as an experiment or trial?
Re rates of flow - these are certainly dependent on the receiver as well as the tanker as has already been stated - thirsty F4s and Buccaneers were always a welcome sight as they could gulp our fuel much more quickly than, say, Lightnings.
Some very interesting info here that I did not know. I flew KC-135s for 15 years. Just as an example of flow rates our max rate was 6000 pounds per minute. Most large aircraft could take it at that rate. Most fighters took about 1600 ppm. That is with the boom. Don't remember P&D rates.
I don't own this space under my name. I should have leased it while I still could
In 1965, with the grounding of the UK tanker force we leased a number of KC135 with a drogue on boom arrangement. IIRC it was Exercise Billy Boy. 
Rick - our centreline rate of flow was 4,000 ppm using the Mark 17 HDU current in the 60s - 80s - can't speak for later versions. As I said, a thirsty F4 could take that no problem. Flow rate from the wing pods was 1250 ppm IIRC.
I never knew the RAF flew KC135s or about the CL131. Learn something new every day. The flow rate form the 135 was based on how many pumps used. It has four hydraulic driven pumps. Four pumps gives 6000ppm. We only used two for fighters so it was much less. It was a long time ago so I may be wrong about how fast an F4 could take it.
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Maybe not the definitive publication of IFR/AAR but the one place with most data about the earlier days is:
'In Cobham's Company' by Colin Cruddas
ISBN 0 9524488 07
© 1994
'In Cobham's Company' by Colin Cruddas
ISBN 0 9524488 07
© 1994
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KC135 with RAF sqn badge
Interesting post pinched from another thread
Mildenhall 13/2/14 inc The BONE's Departure. ? FighterControl ? Home to the Military Aviation Enthusiast
One of the pictures shows a KC 135 with what looks like an RAF Sqn badge on the fin. My first thoughts were that it was 51 working up for RJ. Not the case as I am more than familiar with the goose.
Anyone know the association and what the sqn badge is?
A spotter mate also saw the B1 over Soham (Cambridgeshire) yesterday.
These spotters really take some fine shots. One other in the series is the C130 with the Wescam, several other protrusions including two pairs of tanks. One appears to have a receptacle on the back for a basket. (It could equally be a dispenser for chaff or flares). now why did this strike a chord with me? I just thought it odd that the lengths the UK went too just to fit a pair of extended range tanks to our Js a few years back. Great play made of UK participation in leading some of the Block Upgrade programme yet the yanks just get on with it and make things happen. What happened to our LRDI in the end?
Mildenhall 13/2/14 inc The BONE's Departure. ? FighterControl ? Home to the Military Aviation Enthusiast
One of the pictures shows a KC 135 with what looks like an RAF Sqn badge on the fin. My first thoughts were that it was 51 working up for RJ. Not the case as I am more than familiar with the goose.
Anyone know the association and what the sqn badge is?
A spotter mate also saw the B1 over Soham (Cambridgeshire) yesterday.
These spotters really take some fine shots. One other in the series is the C130 with the Wescam, several other protrusions including two pairs of tanks. One appears to have a receptacle on the back for a basket. (It could equally be a dispenser for chaff or flares). now why did this strike a chord with me? I just thought it odd that the lengths the UK went too just to fit a pair of extended range tanks to our Js a few years back. Great play made of UK participation in leading some of the Block Upgrade programme yet the yanks just get on with it and make things happen. What happened to our LRDI in the end?
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Dragartist
Spotters can discover many things which the authorities would like to keep to themselves, like for example the strange aircraft sighted at Lakenheath way back in 1956 that Flight magazine got to hear about and which they subsequently mentioned in the magazine and was later identified as a U-2.
More here: 1956 | 0661 | Flight Archive
1956 | 1647 | Flight Archive
1956 | 1777 | Flight Archive
These spotters really take some fine shots
More here: 1956 | 0661 | Flight Archive
1956 | 1647 | Flight Archive
1956 | 1777 | Flight Archive
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Originally Posted by Tankertrashnav
Thats always been theoretically posible with 3 point tankers, but would involve some pretty scary formation flying. I'm wondering if it has ever been done, if only as an experiment or trial?
Big version: http://www.xf90.com/images/R3Y-2/R3Y-2-300.jpg
While the USAF could only manage a triple:
Almost - the port F-100 seems to be unplugged.
