by Tommy H. Thomason

Thursday, August 26, 2010

The Stoof

Steve Ginter has an S2F-1 monograph in work; it should be available later this year. See his Naval Fighters web site HERE. If you can find Fall 2007 (#8) issue of Aerospace Modeler Magazine, it included a build article on the 1/48th Collect-Aire S2F and details on the S2F.

The nickname "Stoof" was derived from its original designation, S2F. The originally approved name was Sentinel. This was changed to Tracker when the COD (Trader) and AEW (Tracer) versions were named.

Designations Pre/Post 1962:
S2F-1     S-2A
S2F-1S   S-2B
S2F-2     S-2C
S2F-3     S-2D
S2F-3S   S-2E
S2F-1S1 S-2F (A very rare instance of a prior designation being reused in the post-1962 lexicon)

The S2F-1 has long been represented in 1/72nd scale by the excellent Hasegawa kit. Kinetic has now released a 1/48th scale "S2F"kit which represents the S-2E/G.

Once upon a time (that's me as a pre-teen, between my brother John Gregory and a naval aviator, John Brandenberg, who let us take a close look as his VS-21 S2F-1 in 1956 or thereabouts.

Short version of the differences between the Stoofs:

1. There were three fuselages, the S2F-1, the S2F-2 (S2F-1 with a bigger bomb bay), and the S2F-3. The S2F-3 center fuselage was longer than the -1's by 18 inches, 14 forward of the wing and 4 aft. The pilot compartment was increased in length by six inches by moving the aft bulkhead aft without changing the location of the window, which resulted in an increase in the length of the equipment operator's work space of eight inches. Note: the S2F-3 cabin was not widened externally as has been reported; there was an increase in internal width of three inches in the upper portion of the compartment accomplished by changing the fuselage skin in that area from skin/stringer construction to a honeycomb panel. The cabin window was also enlarged and it appears to have been relocated a bit farther forward.*
 * As near as I can determine from pictures compared to a Grumman forward fuselage drawing, this is the size and location of the S2F-3 (S-2D and subsequent) crew compartment window:

2. There were two horizontal stabilizers, the original S2F-1 and a bigger version on the S2F-2/3 to offset the bigger bomb load and longer fuselage respectively. The S2F-3 had a greater wingspan/aspect ratio by virtue of the addition of rounded wingtips.

3. The big radome over the cockpit appeared early in S2F-1 production and was also on the S2F-2; it was deleted from the S2F-3. (The antennas were moved to the rounded wing tips.)

4. The aft end of the nacelles changed, first to add a "parrot beak" or "hawk's bill" fairing during S2F-1 production and then to cut the beak/bill off for the S2F-3 (S-2D)for more sonobuoy capacity. The two larger holes in the S2F-1/2 sonobuoy dispenser were for the SSQ-1 directional sonobuoy but it proved unsatisfactory in service so the bigger holes did not have the store retention clips.
S2F-1s (S-2As) with BuNos 129XXX and 133XXX and all S2F-2s (S-2Cs) were built with the small nacelle that faired into the upper surface of the wing at the trailing edge. All later S2F-1s (136XXX and higher) were built with an aft nacelle which extended over the top of the trailing edge of the wing and above and aft of the opening in the rear of the nacelle. The Canadian S2Fs had the early aft nacelle.* The Japanese S2Fs had the beak/bill.

Note that early S2Fs had a different main gear wheel hub as on this VS-21 S2F-2. They also had a smaller "head" on the extendible Magnetic Anomaly Detector located at the tail of the airplane.

5. The original cockpit of the S2F-1 and -2 had the control columns extending out from the instrument panel and the pilot sat in a bucket seat on a seat-pack type parachute, strapped in with a conventional seat belt and shoulder harness.

With the S2F-3, the control columns were relocated to be between the pilots and the instrument panel and the seat was changed to one with a back-pack type parachute and a restraint system requiring a torso harness.

This excellent picture of an S2F-3 in flight test at Grumman illustrates the differences between it and the earlier S2Fs:

Note the increased distance between the cockpit window and the red propeller warning stripe compared to the lead photograph, the bigger crew compartment window, the rounded wingtips that housed the antennas that had been in the strut-mounted "pod" over the cockpit, and the increased span horizontal tail. The retro-smoke marker located on the lower right fuselage between the cabin door and the dust bin radome was rmoved. (It was reinstated on the S-2G.)

The forward angled probe under the fuselage was the barrier pickup. It was added early during S2F-1 production after a barrier crash. See my Navy aircraft history blog entry Here. It was no longer necessary after the U.S. Navy completed its switchover to angle-deck carrier. My impression is that it was no longer installed at some point during S-2E production.

The higher gross weight of the S2F-3 required power plant installation changes as well:

Compare the size of the crew compartment window, the location of the warning stripe, and the engine nacelle of this Reserve S2F-1 to the above:

The "plumbing" in the nose cap was also rearranged:
The final U.S. Navy Tracker was the S-2G, which were modified S-2Es:
A folding antenna was added with an avionics upgrade where the barrier pickup had been. Note that extra sonobuoy dispenser scabbed onto the right side of the right nacelle (the 1/48th Kinetic kit has two but only one is needed) and the fuselage-mounted retro smoke marker system was reinstated. The S-2G was also operated by the Australians.

* The Canadian S2Fs were initially all but identical to the early production S2F-1s. However, the avionics suite underwent a series of improvements. For almost everything you need to know about the Canadian program, see This Excellent Website, identified to me by Robert St-Pierre, who also provided this picture of a CS2F landing on Bonaventure.
The "cans" on the CS2F wing tips contained passive ESM antennas, which presumably were incorporated in lieu of the similar S2F system located in the pod above the forward fuselage of the S2F-1/2.

Kinetic Kit Redux

Mike Belcher of Belcher Bits has done an evaluation of the Kinetic S-2E/G fuselage with an eye toward creating aftermarket decals and options for the CS2F. In the process, he has identified a problem with the length of the aft fuselage of the kit. See HERE.

Mike also offers a S-2E to early S2F-1 conversion kit consisting of new horizontal stabilizers, aft engine nacelle terminations and an instruction sheet, which is on line. Click HERE.

Modelers continue to note shortcomings with the kit's cockpit. It provides a relatively simple version of the later seats, the S2F-1/2 instrument panel and control wheels, (see above) and a rectangular opening to the cockpit rather than an opening with an arch at the top, and is missing the aft (folding section) of the center console. I assume that it's also missing the search light control stick that can be seen in the copilots side window.

In order to provide adequate access to (and from) the pilot and copilot seats, the aft section of the center console could be pivoted upwards against the instrument panel where it was retained by a latch on the glare shield. The following are pictures of an S2F-1 cockpit. One shows the arch at the top of the opening to the cockpit.

The S2F had a fixed slot in the outboard leading edge of the wing.
The slot opening was farther forward on the underside of the wing. Note that there was a deicing boot on the lower surface of the wing aft of the slot opening as well as one on the leading edge of the wing.
Another view of the slot and boot on the lower side of the wing.

Another question raised about the Kinetic kit is the location of the jury struts used to secure the wings when folded. There were two very small permanent attach points on the centerline of the upper fuselage.

The wing-attach point for each strut was located inside a small door.

Note that the location of the attach point was different on the left and right wing.

The forward strut angled forward when installed:
For more pictures of the wing jury struts, among other things, click Here.

The Kinetic kit also omitted the search light reflector, etc. inside the searchlight housing. The light was mounted on a gimbal and aimed using a removable control handle mounted in the copilot's side window. (The picture of the gimbal has been rotated so you're looking down from above; it was lifted from this website.)

Click Here for pictures of the control handle (Note that the cockpit is an S2F-1 procedures trainer, not an S2F-3's.)

Click Here for a discussion of the difference in cockpit side windows between early and late airplanes.


  1. Are there any visual difference in the versions in the new Kinetic Stoof kit

  2. The new 1/48th scale Kinetic kit is billed as the S-2E/G. However, looking at the pictures of the sprues on the interweb, there are aft nacelle parts for the later S-2A (S2F-1) nacelle and the radome over the cockpit on the S-2A (S2F-1) and S-2C (S2F-2). The instrument panel/control wheels look like those in the S-2A/B cockpit rather than providing separate control column/wheels as in the S-2E. It also looks like the cabin windows are the smaller version in the S-2A/B. It would be fairly easy to convert this kit to an S-2A (S2F-1) by shortening the fuselage and cutting down the wingtips and horizontal stabilizer, in addition to other minor changes.

  3. Great info, looks like the Kinetic kit will need a bit of work but it still looks like a winner. Thanks for posting all these details, they are very useful. I'd be interested in hearing your feedback once the kit is released.


  4. I'll keep updating this entry as I see suitable comments and photos on the web but it will all be secondhand since I only build 1/72nd scale kits...

  5. Thank you for all these interesting information !

  6. In addition to providing the S-2A radome and aft engine nacelles on the S-2E/G sprues, Kinetic also included two different fuselage nose caps that are intended to correspond to the early (S-2A/C) and later (S-2D and subsequent)versions.

  7. Great infos site. Do you have any details on the Canadian Tracker (S2F-1)especially the ECM cans on the tip of the wings? these were the only trackers in the world that had those.

  8. I'm afraid that I can't do justice to the Canadian Trackers. Over time, there were three different configurations built under license in Canada and confusingly designated originally as CS2F-1, -2, and -3, with the -1 being similar to early production U.S. Navy S2F-1s, the -2 being the second production lot with a different avionics suite and minor external changes, and the -3 being a midlife modification of the -2s. The ECM cans on the wing tips appear to have replaced the function of the radome above the cockpit. They are about 9" in diameter and 16" high. My understanding is that they were removable and appear to have been removed and reinstalled from time-to-time on the same airplane.

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  10. I am currently assembling the Kinetic kit "big time" and would like to make a few observations. This is a great kit so I don't would to turn anyone off to building it. The work they have done is what I have been waiting for a long time. If someone is really into the details of the Tracker this is a great kit built right out of the box except for one correction, the constant speed generator scoop on the left nacelle need to be placed on the right lower inboard side, not on the left side of the nacelle as the instructions call out. It would look very strange to see it there. On the box art Kinetic didn't even display it there which even makes this mistake all the more funny that they could have missed it. I am making corrections to the kit to the things you have noticed as well as correcting the small scoops on top of the cowlings that are to the S2F-1/-2s to the larger scoops of the -3s. I think I will just cast some from the collect-air kit. I have produced a cockpit aft bulkhead to correct the square top shape of the door as well. The whole cockpit lacks detail but it may not be that big a deal since it is hard to see in there anyway. I am adding detail in there anyway. The area I feel that lacks the detail the most is the engines. If I were only going to add detail in one area this would be it. I am also going to do something about the shape of the searchlight lens. I do want to say again that this is a very nice kit and really worth building. They have really done a nice job on the basic airplane and improving it would mainly involve adding detail, not making big corrections to the kit itself. I most likely look at this kit from a little different perspective than most modelers because I worked on the S-2 as a mechanic in the 1980s and early 1990s for CDF. They were all S2F-1s though. My dad also worked on them for CDF and was a pilot that few them in the Navy as well. He was at Sangley Point when your pictures of you were taken. At the time he was a pilot in VS-20 and then VS-21 when VS-20 stood down in june of that year. I am sure he flew that airplane in the photo with you. That is why I can hardly wait for the -1 to be released by Kinetic!

  11. Just a curious question....because the S2-E had a longer fuselage,did Grumman compensate for this also by increasing the HEIGHT of the tail as well as increasing the length of the horizontal stabilizers over the original design specs of the earlier S2-A versions which might have had a shorter vertical stabilizer ?

  12. The size of the vertical fin, trimmer, and rudder wasn't changed between the S2F-1/2 and the -3. The areas of the empennage surfaces are initially established by rules of thumb and wind tunnel test. Flight test establishes whether the engineers got them right. In this case, the existing vertical surfaces must have proved to be adequate for directional stability and control even with the increase in forward fuselage area and engine power.

  13. Thanks "Tailspin"...I appreciate your info and insight regarding the size of the vertical fin.

  14. Juist an observsation on the position of the crew windows in the rear. Your drawing looks right. The windows appear to be JUST behind the prop spinner and the leading edge seems to be about in line with the leading edge of the engine nacelle. The windows were just slightly forward of the overhead escape hatches but do not show up at all in the profile view in the SAC drawings, meaning they are completely hidden by the nacelles.

  15. Building the Kinetic kit right now and it is excellent in most respects. I am having some issue with the paint color. Testors Model Master FS 16440 is drying much too dark. The FS number is the correct one according to many sources, but once dry does not match either my memory, numerous photos or other naval aircraft models I have already built. Anybody been satisfied with another paint manufacturer?

  16. My name is Mike Combs and I was an Ordnanceman on the S2Es at NAS North Island with VS-25 the Golden Eagles. I was on my 1966 WesPac on the Yorktown. VS-25 and VS-23 were the S2E Squadrons on that cruise. I'm writing a book that includes my experiences with this plane from 1965 to late 1967. Do you have any photos of the photo-pod which was mounted on the Starboad wing by an Aero 15 Bomb rack? I was trained to repair and rebuild the Aero 15s for the S2Es. I'm trying to include some of my photoshop art work showing how we installed the photo-pod with the wings folded as we were up on the wings. Do yo have any documentation, photos or a manual covering the Aero 15 Bomb Rack with diagrams? Anything would be appreciated covering the S2E! My email is I would really like to see some photos of your models. Anybody that can supply photos, Information, or even manuals I will gladly include their names in my book for credit of their help.

  17. What changes were made to create the US-2As that were used as utility birds/station hacks until the advent of the Beechcraft KingAir (aka C-12)? Judging from photos, the search radars, searchlight, and sonobuoy chutes were removed. It LOOKS like the starboard weapons bay was de-activated but the port one remained. A "shape" where the MAD boom was housed looks like the original MAD boom in the retracted position. Finally, it appears the former sonobuoy areas received an enclosed version of the parrot's beak on the nacelles.

    Is there I missed/ got wrong (model-wise)?

  18. That sounds right to me except for the deactivation of "the starboard weapons bay". There was never was a starboard weapons bay, only the one on the port. Strictly speaking, the fairing added at the rear of the nacelle was not a version of the parrot's beak but an adaptation of the fairing used for the E-1B and C-1. There were also antenna changes but I haven't looked at that very closely. Small windows were also added along the right side of the fuselage. I thought I'd posted something on those but at the moment, I can't find it...