Tuesday, October 2, 2012

Northrop's Lost Tracker - The N-60

Much like the evolution from vinyl to tape to CD to the cloud, advances in technology always make for that awkward moment when you realize your "state-of-the-art" reproduction tools in one era are pretty much antiquated in another. 

And so it is with the N-60 data. Originally reproduced on a copy machine in the early 1990s, I had the opportunity to get the brochure back for a short time and was able to take some digital images about eight years later. 

What I would have given to have had a nice scanner back in those days.

Nevertheless, we do what we can with the tools we have available at the time. Perhaps another day I will get a third chance.

This was a particularly intriguing subject to me mainly because Northrop proposals for Navy programs are not well known. The fact that a primarily Army and Air Force contractor would pursue carrier-based aircraft raises all sorts of issues for that company, especially in understanding the environment in which those aircraft operate. In short, it ain't as easy as it looks, and it doesn't really look easy to begin with.

A couple of comments before we proceed: When I wrote the caption to image number 8, I knew I had seen a photo of a twin-engine prop aircraft in that angle before. While there is indeed one of the AJ-1 Savage in just such a position, as noted, the photo I was really thinking of was one of the Lockheed P2V Neptune, which was taken shortly before the artist's concept was done. I, of course, unearthed it after the article went to publication.

It is, of course, logical to say that all images of a twin-engine prop airplane taken or drawn from that vantage point would look similarly dramatic. However, I'm fairly convinced that this particular piece of art was deliberately fashioned after the Neptune photo in order to generate a more visceral reaction within the Navy customer examining the proposal. The survival of Naval aviation was being fought over in the Pentagon and in Congress at that time and a strong emotional appeal could only help sell the product. As Northrop was a very dark-horse in the competition, it would need all the help it could get. Or so, I'm betting, the thinking went.

This article was originally published in Airspace Vol. 3, No. 16, March 2012. It is posted here with permission and has approved for public release case number 12-1493.

With that said, let's take a look at the N-60. 

Northrop’s Lost Tracker – the N-60
By Tony Chong

The demands of naval carrier aviation have always presented tough challenges for those willing to build airplanes for that service.  It is a difficult field to compete in and even more difficult for an inexperienced company to win against established opponents.

The rapid advancement of aircraft design in World War II, followed shortly by the start of the Cold War and the transition from the piston age to the jet age, offered a multitude of opportunities for unproven companies to make that breakthrough.  One such opening occurred in 1949 when the Navy’s Bureau of Aeronautics (BuAer) issued an Outline Specification inviting the industry to bid on a new type of aircraft. 

OS-117, as it became known, sought to replace the existing Hunter/Killer teams then in service with a single, self-contained platform that could detect, identify, track and destroy enemy submarines in an ocean environment and in all weather.  Additionally it was to be operable from all of the Navy’s carriers, ranging from the small CVE-105 class escort carrier all the way up to the very large CVB-41 class battle carrier.

Eighteen companies responded with a total of 24 proposals.  Among them was one from heritage Northrop Aircraft, Inc., an unlikely entrant with no previous carrier aviation experience.1 Nevertheless the company submitted a heavily detailed design with the in-house designation of N-60.

Northrop envisioned a conventional mid-wing, twin-engine aircraft of all-metal construction with a span of 61 feet and a length of 48 feet, 10 inches.  The outer wing panels would stow for more compact deck storage by rotating the leading edges up and folding the panels aft.

The N-60 also featured a bulbous forward cabin for the four-man crew and a fixed, aft belly radome containing the AN/APS-33A radar.  A single Mk. 41-1 light-weight torpedo was to be carried in the weapons bay, along with rack-mounted sonobouys.  Additionally six 5” rockets could be fitted, three under each wing.

Multiple access panels, doors and hinged sections for easier maintenance were an integral part of the proposal.  Aircraft sub-assemblies were also designed for simplicity in construction and repair.  The engine nacelles were to be fully interchangeable as part of that goal. 

Propulsion was to be provided by two 900hp Wright R-1300-C7B6 Cyclone 7 radial engines, each driving a 12-foot diameter two-bladed Aeroproducts prop.  Designed for catapult launch at 73 knots airspeed, the N-60 could also accommodate two Aerojet 3500lb thrust JATO (Jet-fuel Assisted Take-Off) units for short, 300 foot deck operations.

The choice of the R-1300s was intriguing, especially considering most of the other contenders gravitated to more powerful Wright R-1820 or Pratt & Whitney R-2800 engines.  One result was Northrop needed to build as light an airframe as possible in compensation, for instance using magnesium skins instead of heavier aluminum alloys over the outer wing panel box structures.

Despite the detailed submission, the N-60 did not make the down-select to the final three contenders.  Certainly the engine choice must have played a role in the selection, as well as the company’s lack of carrier aviation experience.  Moreover the airframe design seemed tailored to a less robust structure than one required by the Navy for its operations.

In the end, experience did matter.  Heritage Grumman eventually won the competition with a robust submission slightly shorter in length and a few feet wider in span than the proposed N-60.  However, it was powered by two R-1820s driving three-bladed props each, with enough power to meet all requirements with greater speed, payload and range than the Northrop entry.

December 2012 will mark the 60th anniversary of the first flight of Grumman’s XS2F-1 Tracker.  This remarkable plane not only became the Navy’s first specifically designed carrier-borne ASW platform, but a piston-engine survivor in the burgeoning jet age, serving for over twenty years in operational squadrons at sea.

The N-60 in turn would fade into oblivion, one of several unproductive Northrop navy proposals submitted during the 1950s.  It was not until the introduction of the F/A-18 Hornet over 30 years later that Northrop would see one of its designs, albeit one heavily modified by experienced McDonnell Douglas, become a successful carrier-borne aircraft.

1:  Jack Northrop developed the Navy’s BT-1 carrier-based dive bomber, the precursor to the Douglas SBD Dauntless, in the mid-1930s while heading the El Segundo, CA-based Northrop Corp., a subsidiary of Douglas Aircraft Company.  Douglas dissolved Northrop Corp. and made it their Northrop Division in 1937.  When Jack Northrop left the company in 1938 it was renamed Douglas’s El Segundo Division.
References and Notes
An excellent brief overview of the OS-117 competition featuring several of the contenders is found in: American Secret Projects – Bombers, Attack and Anti-Submarine Aircraft 1945 to 1974, by Tony Buttler, Ian Allan Publishing, 2010, pp 168-173
Additional OS-117 information from the Grumman perspective is in Grumman Aircraft since 1929, by Rene J. Francillon, Putnam Aeronautical Books, 1989, U.S. publisher Naval Institute Press, pp 350-352.
A great on-line discussion on OS-117, with images of some of the competing types not shown in Buttler’s book, is found here: http://www.secretprojects.co.uk/forum/index.php/topic,584.0.html

Tony Chong is a historian, photographer and a contributing editor to airspace. He leads activities in the Aerospace Systems Display Model Shop and works in El Segundo.

Photo/Image Captions 
1) 100_0009w: The cover art for the Northrop N-60 brochure shows the aircraft banking over a late Essex class-type carrier with spurious markings on the forward deck.  Note the size of the N-60 launching from the portside catapult.  The “23” on the cover indicates this is the 23rd brochure put out by the company.  Photo credit: Tony Chon

2)  Img989w: A scan of a 3-view drawing of the N-60 with a human figure for scale.  The “NS-60” notation on the upper right-hand corner of the sheet stands for “Northrop Specification 60.”  Most Northrop N-numbered projects also came with specifications details.  Early in the company’s history the N and NS numbers would usually match.  But as the system progressed into the 1950s the numbers began to diverge widely and rapidly.  Credit: Tony Chong collection 
3)  100_0016w: This photo of the general arrangement 3-view from the brochure adds a few more details.  While Northrop had a fixed belly radome, Grumman’s design featured a retractable “dustbin” housing that could be stowed during launch, transit and recovery, lessening drag during non-mission portions of the flight.  Note also the dihedral on the wings outboard of the engine nacelles.  Photo credit: Tony Chong
4)  100_0003 (2)w: A detailed fold out drawing of the landing gear and tail hook was included the brochure as well.  Note the rather spindly nature of the nose gear and the unusual retraction process where the gear folds rearward and the wheels go forward.  Photo credit: Tony Chong 
5)  100_0003w: This illustration of the N-60 on the elevator of a carrier shows the wings folded in the stowed position with the leading edges up and the upper surfaces of the wings facing inboard.  The picture also shows Grumman F6F Hellcat fighters on the same deck.  Hellcats were withdrawn from active duty carrier-based squadrons in 1948, which makes their inclusion in this 1950 scene a puzzling anachronism.  Photo credit: Tony Chong
6)  100_0007w: The complex wing-folding mechanism is illustrated in this drawing, which also shows the forward locking pins, eyelets and actuators.  Photo credit: Tony Chong
7)  100_0008_2w:  With space on Navy carriers at a premium, deck-spotting charts like this one from the N-60 brochure highlight the advantages of folding wings for aircraft storage.  Photo credit: Tony Chong
8)  100_0004w: This illustration from the brochure shows the N-60 on the deck of CVB-42 USS Franklin D. Roosevelt.  It is eerily similar to a photo of a North American Aviation AJ-1 Savage on the deck of CVB-43 USS Coral Sea that was shot just after the brochure was published in April 1950.  Photo credit: Tony Chong 
9)  100_0009aw: Accessibility and ease of maintenance on the N-60 were prominent selling points touted by Northrop.  This drawing shows how those features would operate for engine repair or change-out.  Photo credit: Tony Chong
10)100_0018w: A production breakdown drawing was also included in the brochure, where Northrop said it designed the principle airframe joints to require a “minimum of manufacturing and tooling hours.”  Photo credit: Tony Chong
11)100_0006w: This cut-away illustration shows crew stations and major equipment and parts placement within the N-60.  Note the torpedo just aft of the crew compartment and forward of the radar equipment.  The crew included the pilot, “assistant pilot,” a forward-facing “radar operator” and a rearward-facing “countermeasures operator.”  Photo credit: Tony Chong
12)100_0008w: Pilot forward visibility and the AN/APS-33A radar range limits are illustrated in this drawing.  Photo credit: Tony Chong
13)100_0002w: This nicely done illustration shows an N-60 in flight over a coastline area.  While visually interesting it would not be the normal area of operation for the airplane.  Photo credit: Tony Chong


  1. Cool. Nice job with the images, even if you didn't have a scanner.

  2. Once again Tony, you've dug up a real treasure! Thank you so much for sharing these forgotten gems with us.

  3. Interesting stories, Tony. I enjoy reading them.

  4. Fascinating, truly fascinating. Speaking of Northrop Navy projects, any chance of seeing something on the N-285B? I saw a brochure on a co-worker's shelf when I was working on TSSAM, but never got a chance to slip it out of the building and copy it. OTOH, I have, somewhere, a brochure for a study Northrop did for a F-5G(F-20)/Lavi hybrid, intended to get the program cost down.

    1. Hi Evan,
      The N-285B is under consideration, but it will be a while down the road. As for the F-5G Lavi hybrid, oddly enough we have a model of that vehicle in the shop right now. It would've looked rather nice. I'd love to see the brochure on that sometime...