AAR question..

[airbee]

I've always wondered - and asked at Mildenhall once with no real response - what the advantages\disadvantages of the two types of refuelling system were.
The drogue system has always seemed to me to be the the most versatile and practical and yet the Yanks have continued with the boom for many years. There must be advantages etc associated with both and I would be v. interested to know about them. I've wondered for yrs - with the new US contract - and looking just now at Tonks's shots brought the whole thing to mind again.
Thks ;-)

[Chris Trott]

Obviously that is just an outline, but like all things it is not that simple. If I was to get the perfect tanker, it would have 2 wing hoses and a centreline hose, with a boom and a boom receptacle (even an probe as well like the E3D)... that way it would be ultimately flexible. Sadly that is not the plan... oh well :roll:

Actually, they do exist. The KC-135R(ARR) with the MPRS (Multi-Point Refueling System) is exactly what you speak. Unfortunately, there are only 12 of these aircraft currently configured to accept the MPRS out of the approx. 24 KC-135R(ARR) aircraft. The (ARR) stands for "Air Refueling Receiver) meaning that the aircraft are equipped with a boom recepticle over the cockpit of the aircraft.

The reason the USAF went for the boom was because a large portion of the tanker's original role was to refuel the nuclear bombers on their way to the target. As such, they would be passing large amounts of fuel and the bomber crews would have been flying for well over 12 hours on the return leg so a system was needed where the relatively fresh (~4-hours in the air) tanker crew could "assist" in making sure there was a hookup and once the hookup was made, the system would be relatively easy to maintain connection so that hopefully the fueling could be made in one contact instead of multiple. For many years (well into the 1970s) most USAF fighters and attack aircraft used probe-type refueling, and several models even had both types of refueling systems onboard! In the end, the need to modernize and standardize the USAF tanker fleet (the fighters and attack aircraft were still using Air National Guard-operated KC-97s) forced the conversion to all-boom recepticle systems for the USAF and relegating probe refueling for many years to the dreated BDA (Boom-Drogue Adapter) which was about 12 feet of hose and a basket attached to the end of the refueling boom of a KC-135. The BDA was universally despised because for the tanker crews it meant they couldn't refuel recepticle aircraft (BDA was "hard coupled" to the boom when installed) and the receiver crews hated them because they moved a lot and the small hose meant that separations of both probes and BDAs was a regular occurance with KC-135s returning with the probes of unfortunate (predominantly US Navy) probes or the unfortunate receivers returning with most (or all) of a BDA still attached to their probe creating a very hazardous situation (especially for the Navy with the need to trap on a carrier).

Also, the KC-10 was the initial installation of the MPRS, but unsatisfactory flutter was encountered when they were installed and the 100 MPRS pod pairs were moved to the KC-135 fleet in the late 1990s where they are now being used by the KC-135Rs at Hickam AFB, Hawaii, McConnell AFB, Kansas, & Grand Forks AFB, North Dakota. The French actually pioneered the MPRS system where it was installed into their KC-135FRs that had their BDA's permenantly attached to a modified boom and the boom operator removed and the boom controls moved to the front of the aircraft where it was mostly an "up-down" switch to deploy and retract the boom and the receivers fly to the drogue wherever it ended up.

Anyway, enough rambling. I've just read both an excellent AeroFax book on the KC-135 (for the 3rd or 4th time) and another book I recently got on the history of Air Refueling that are excellent sources of information on the hows, whys, and the fun stuff that has occured since the first airplane was refuelled in mid air shortly after WWI as part of a world record endurance flight in California.

[airbee]

ASK CBFS.ORG!
Thks to you both. In two answers a technical, tactical and historical survey of the arena. I consider myself well and truly answered.
Thankyou.

[Chris Trott]

Oh, I forgot earlier, there is a 4th base where KC-135's with MPRS pods are based - Mildenhall and the KC-135R(ARR)'s are all at McConnell AFB.

[Hot_Charlie]

Obviously that is just an outline, but like all things it is not that simple. If I was to get the perfect tanker, it would have 2 wing hoses and a centreline hose, with a boom and a boom receptacle (even an probe as well like the E3D)... that way it would be ultimately flexible. Sadly that is not the plan... oh well :roll:

Actually, they do exist. The KC-135R(ARR) with the MPRS (Multi-Point Refueling System) is exactly what you speak. Unfortunately, there are only 12 of these aircraft currently configured to accept the MPRS out of the approx. 24 KC-135R(ARR) aircraft. The (ARR) stands for "Air Refueling Receiver) meaning that the aircraft are equipped with a boom recepticle over the cockpit of the aircraft.

It doesn't have a centreline hose though, although obviously there is a drogue attachment available for the boom. Ultimate flexibility would be to have (as Tonks says) a boom and a centreline hose. Although the KC-135R with MPRS offers combinations of the two, it can't offer 2 wing hoses, a centre hose and the boom in the same mission.

[Chris Trott]

The KC-10 originally could offer all, but as I said above, the flutter problem nixed that idea.

Also, with the KC-135 it is much better to have only 2 wingtip hoses. A centerline hose reel (which was tried) was marginally effective because it had to be VERY long to get into smooth enough air for it to be workable. As well, when the centerline hose was in use, the wingtip hoses were unusable due to proximity of the 3 aircraft. When you use the boom & 2 hoses, you can refuel 3 planes at once because the centerline receiver is separated vertically from the who hose receivers.

[bobdawkins]

I was in Cambridge Monday late morning, doing a delivery on a building site, whilst waiting, perused the sky, very clear blue sky odd cloud here and there, and spotted what I believed to be a Tristar, the aircraft was fairly high up, but it was defiantly one of these aircraft (Isay this due to the large main wing and how it also had a long nose as it were) heading over Mildehall, too high to land, but could have being on the return from a refuelling mission, would this have been from Mildenhall or Brize Norton as I thought Mildenhall only used the KC135 or similar

[Chris Trott]

Well, there are TriStars at Brize, so if it was a TriStar, that's probably where it was going. You are correct that only KC-135s are based at Mildenhall, but it's always possible that a TriStar may be going over to Mildenhall for some reason. One of the USAF Civilian Charter companies also flies TriStars, so it could have been them as well.

The arrival into Brize is quite steep from some directions due to the need to separate from the London traffic, so it's not unheard of for them to still have some height.

[Chris558]

Are there any plans for AAR for the RAF's Helos (Merlins) maybe using Hercs or the A400M?