by Tommy H. Thomason

Saturday, June 27, 2015

Things Under Wings: Inflight Refueling Buddy Store

1 July 2015: Rick Morgan provided additional pictures of the early store that I've incorporated.

29 June 2015: Jim Rotramel provided additional information and photographs that I've incorporated in the post.

Compromises and innovations were necessary to accommodate the operation of jets from aircraft carriers. One of the enabling practices was inflight refueling. One approach was the development of a buddy store that could be added with minimal modification to any carrier-based airplane with an external stores capability. For the background on this, see http://thanlont.blogspot.com/2013/10/texaco.html and http://tailspintopics.blogspot.com/2011/07/douglas-low-drag-external-fuel-tanks.html.

There were originally two buddy stores used operationally, one developed by Douglas, which used the model number D-704 (D for Douglas, not design) and the other by North American, which was only used on the FJ-4B Fury. The Navy subsequently procured a virtually identical, lower-cost store manufactured by Sargent Fletcher, which also produced external tanks (see http://tailspintopics.blogspot.com/2013/06/things-under-wings-f4h-f-4-phantom.html). Sargent Fletcher subsequently designed an improved store, the A/A42R-1.
The external bulges on the original store were necessary to provide clearance for the hose reel.
 
For some reason, the bulges on the upper half of the store were larger than the ones on the lower half.
Jim Rotramel Photo 

There were two aft-facing status light on the original store. The left light was amber (yellow) and the right, green. When the basket had been reeled out and the store was ready to transfer fuel, the amber light went on. After the receiving pilot plugged into the basket and moved forward three to six feet, the amber light went out and the green light came on, indicating that fuel was flowing from the store.

Rick Morgan provided the following pictures which complete a walk-around set of the "D-704" store (he also reported that in the fleet, even the latest version from Sargent Fletcher is referred to as a D-704.

The original Sargent Fletcher store was used through at least 1985 based on this photo provided by Rick Morgan.
Note that the dedicated KA-6D tanker would often carry a buddy store as a backup in case its internal, aft-fuselage mounted system went "sour".

The afterbody of the later Sargent Fletcher store was modified to eliminate the bulges. The change resulted in a discontinuity in the exterior shape at the beginning of the hose-reel section. The opening in the aft end of the store was also slightly raked so it was at an approximately 90-degree angle to the basket as it was reeled in and out.
Jim Rotramel Collection

Just barely visible on the bottom of the store is the jettison tube for dumping fuel from the store if required.
Jim Rotramel Photo
This was a feature on the S-3 installation only. The opening is covered by a blank plate on the F/A-18E/F.
Another notable change to the later store was the fairing for the status lights on the after body. It had a deeper fairing for an additional light.
Jim Rotramel Photo

The green light on the upper left indicated that fuel was flowing to the receiving airplane. The yellow light on the lower left, when steady, indicated that the store was ready; when flashing, it indicated that the receiving pilot had pushed the drogue/basket too far forward and fuel flow to the probe had stopped. The red light on the upper light turned on when there was a hydraulic failure in the store so fuel couldn't be transferred.

According to Jim, there were at least five different versions of the later store, which is still in use. The first three were specific to A-6, S-3, and F/A-18E/F; the differences were internal. The next two incorporated a redesign of the Ram Air Turbine propeller hub on the nose of the store.

"D-704" Buddy Store Aftermarket Products

1/32: http://www.scaleaircraftconversions.com/moreinfo.cfm?KIT=18

1/48: http://www.cobracompany.com/48012.htm

1/72: http://www.armahobby.com/d-704-buddy-tank-early-60-70-1pcs.html

          http://www.hannants.co.uk/product/FDR72027

A/A42R-1 Buddy Store Aftermarket Products
 
1/48: http://www.wolfpack-d.com/  (Click on resin, then 1/48, then WP48132)

1/72: http://www.armahobby.com/31-300-buddy-tank-late-80-90-1pcs.html

          http://www.wolfpack-d.com/  (Click on resin, then 1/72, the WP72069)

Note: the Wolfpack kits provide both types of RAT hubs

10 comments:

  1. I looked at these a few years ago, when other modellers queried what store was used and I'd read that the D-704 had been superseded. I went to the manufacturer's website - so is this any use to you?

    http://www.cobham.com/about-cobham/mission-systems/air-to-air-refuelling/products-and-services/hose-and-drogue-systems/buddy-refuelling-pods.aspx.

    The 31-301 would appear to be current.



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    1. Thanks very much for that link. I hadn't see those data sheets before. There is some confusion about the 31-300 model number for the early configuration. I relied on a Sargent Fletcher data sheet that depicted the earlier store: it was identified as the 31-300-48053; the S-3 was not listed as an aircraft application. The model number is the same on the Cobham 31-300 data sheet but it includes an illustration of the later configuration and lists both the S-3A and S-3B as aircraft applications (but not the F/A-18E/F, which is listed as an application on the 31-301 data sheet). Sargent Fletcher was acquired by Cobham in 1994.

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  2. Tommy,

    That's a first for me - and probably a last! Yes - the text describing each pod was somewhat confusing. Regarding Aftermarket, there's also the Wolfpack Design 1/48 item which I have (somewhere), no. 48132.

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    1. What's even more confusing is that even the later pod is often referred to in the fleet as the "D-704". I've added the Wolfpack A/A42R-1 kit to the list in the text: I'd missed it and it's a pretty well documented kit; it includes the later RAT as well.

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  3. Tommy,

    Freightdog also offers a D-704 pod: http://www.hannants.co.uk/product/FDR72027

    Also, the produce the french navy refuelling pod for the Etendard IVM/P wich, if I'm not wrong, is the Douglas B827 design: http://www.hannants.co.uk/product/FDR72010

    I believe that's the same pod still in use, even in Rafales: http://www.studentsoftheworld.info/sites/sciences/img/9111_rafale-super-nounou%5B1%5D.jpg

    I don't know if this pod, somewhat smaller than the D-704 and A42R-1 was ever used by USN / USMC.

    Great post!

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    1. Pablo,

      Thanks for that. The French Navy pod appears to be the front and back end of the D-704 (RAT and hose reel) so there is no fuel in the store itself. I've not seen it on a US airplane.

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  4. I noticed that these stores on Super Hornets and on trollies when I visited USS Theodore Roosevelt in 2009 and USS George H.W. Bush in 2011 had "- 5" stencilled on them in red (possibly dayglo) which got me thinking. All had the revised spinner. I then found this - From ATP-56(B) found on the MOD website describing US refuelling operations -

    http://www.raf.mod.uk/rafcms/mediafiles/8158c49c_1143_ec82_2e6260d6f772084d.pdf

    Document is dated DEC 07

    Each aircraft's operation is described including which pod is used, e.g. -

    for the S-3B - The A/A42R-1 refuelling store, P/N 31-301-48310-2,

    for the FA-18E/F - The A/A42R-1 refuelling store, P/N 31-301-48310-3/4/5

    Maintenance manual identified as A/A42R-1 Buddy Store Maintenance Manual NAVAIR 03-10JA-34

    So the pods I saw were Dash 5's presumably? Both pods are presumably variants of the 301 pod (if 301 in the P/N is in any way connected to the Cobham designator).

    Unfortunately, the only photos I took are of the front 1/3 of one on a VFA-31 F/A-18E in 2009 and a shot from above of 2 pods on trolleys with protection over their spinners in 2011.


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    1. The A/A42R-1 is one of those stores whose designations are monumentally screwed up. To understand what is going on, one has to refer to the part number (P/N), which is 31-301-48310. So, instead of correctly designating the ARS variants as A/A42R-1 through A/A42R-5, they are all grouped under A/A42R-1 with P/Ns 31-301-48310-1 through 31-301-48310-5. Genius, right?

      The -1 was used by the A-6E, the -2 by the S-3B (with the angled vent pipe midway along the bottom), the -3 by the F/A-18E/F, -4 was not used, and the -5 was modified by AYC 1360 between Jul 07 and Dec 08 with the new RAT for use by the F/A-18E/F.

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  5. Early in my Naval Aviation career as an Ordnanceman I was assigned to an A4D-2 squadron VA-34 out of NAS Cecil Field and usually found on the USS Saratoga CVA-60. As the junior man I was detailed to serve on the squadron Buddy Store Team. We had one ADJ (Mech), one AE (Electrician), one AMH (Hydraulics), and one AO (me). Anytime a buddy store required loading it was our task to load it, day or night. Since it had 30 inch suspension it had to be loaded on the centerline rack. My job was to ensure it was safely hung and sway braced down, ejector rack armed, and buddy store.guillotine armed. An interesting thing about the "basket" is that it had a string of lights around it to enable pilots to aim at it during night time refueling.

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  6. I worked on D-704's and 301's during Desert Storm when I was part of the CVW-8 Buddy Stores team onboard the USS Theodore Roosevelt (CVN-71).

    I was normally an AMH (Aircraft Stuctural Mechanic-Hydraulics) on F/A-18C's in VFA-87, but was assigned to the Air Wing during that deployment as our squadrons contribution to the Buddy Stores team. At that time, they were only used on on the A-6 (VA-65 and VA-36 were the squadrons A-6 squadrons in CVW-8 then)and the S-3 (VS-24).

    As I recall, we only had a one or two D-704's and a few 301's.

    The lights on the drogue basket Gunner referred to above were powered by a self contained 28VDC generator on the basket that was driven by ram air. When the hose extended and the basket was caught in the air stream, the lights would power up, when retracted, they shut off.

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