Tony Chong: Northrop's TAB for All Seasons

It's been a long time since I've posted regularly. The answer is partially revealed here tonight.

For the last few years I've been writing articles for a variety of in-house magazines attached to the Northrop Grumman Engineering Department. Starting sporadically with "The Leading Edge," a traditional hard-copy magazine, to "VelocitE," a combination pdf/on-line journal, to the current "Airspace" and its pure, on-line format, I've been gradually writing more and more current and historically-themed pieces.

Earlier this year I was given my own column. While exciting, it's been very time consuming as there is a lot of research involved in some of the articles. Also I've now gone on a 9/80 schedule at work, making for longer days and tougher commutes. Since I do all of my writing on my own time at home, something had to give. Sadly, that included blogging (I think eBay stock dropped as a result, too).

While I've gotten a lot of good response to my articles, I couldn't share them with anyone outside of the company. Fortunately, Diane Hensley, my very generous editor, granted me permission to reprint these on my blog.

However, before I could do so, I had to get them cleared for public release through the Northrop Grumman system. That has been an interesting experience and something of an eye-opener. In today's environment, everyone is being extra cautious. It's understandable, but very frustrating at times.

I now have several articles that have cleared the process - photos included - with several more in the queue. I hope now that I will be able to post more regularly and you can see the results of my work. I hope you enjoy them.

This article was published in Airspace vol. 2 no. 7, May 2011. It is reprinted here with permission and has approved for release case number 12-1465.

Northrop’s TAB for All Seasons

By Tony Chong

Perhaps one of the most unusual designs proposed by the heritage Northrop Corporation was the Truck, Airplane, Boat (TAB) Vericraft triphibian, an ungainly looking vehicle that attempted to be the all-in-one answer to the U.S. Army’s looming tactical needs.

TAB was developed in the mid-1960s in an attempt to secure participation in an Advanced Research Projects Agency (ARPA) program called Project AGILE. One of the issues under investigation was the problem of mobility and logistical supply to remote bases and outposts in inaccessible environments. With the U.S. increasingly involved in the Vietnam conflict this was a major concern for military planners.

Northrop envisioned a rugged, easy to build, low-cost aircraft that had the ability to operate effectively not just in the air, but on the water and on land as well. While primarily designed for the short-range utility cargo mission, it was to be easily adaptable for use as a troop transport, weapons carrier, mobile command post or medical evacuation vehicle.

The proposed craft featured a rectangular box of a fuselage outfitted with a catamaran hull, retractable wheels and rotatable wings and tail. Twin Pratt & Whitney PT6-B15 turboprop engines, mounted in a single pod nacelle, provided power to a 7.5 foot shrouded propeller. Engineered with a constant-chord wing with a span of 60 feet, the TAB was to be 40 feet long, with a folded wing width of 9.5 feet and a height of 13.5 feet. The cargo compartment was to be 6 feet high, 6 feet wide and 15 feet long. Gross weight, complete with up to 4,000 lbs of cargo, was projected at 12,000 lbs.

Conversion to any operational mode was anticipated to take approximately 10 minutes. Additionally, all mode conversions could be done onboard the TAB during water operations. The vehicle was also scaled to fit into the cargo hold of a Lockheed C-130 Hercules transport for long, overseas deployments.

Northrop expended considerable time and effort in this design. A multi-volume proposal brochure was developed that included cost and operations comparisons to other proposed Army vehicles, including the fixed-wing de Havilland of Canada CV-2 (later C-7) Caribou and the rotary-wing Boeing-Vertol CH-47 Chinook and Bell UH-1 Iroquois (Huey).

Performance was projected to be modest. The 130 mph air speed would be slightly faster than the Huey but much slower than the Caribou or Chinook. Truck speed would top out at 50 mph. Ironically the boat mode would provide the best performance with calm water speeds up to 35 kts.

A detailed scale model was built toward this effort, along with a larger scale radio controlled model of the basic TAB design. Interestingly enough, no formal N-number was attached to the program. While a Preliminary Design (PD) number was likely given to the TAB, its identity has proved elusive thus far.

In any event, the program did not go forward. ARPA declined to offer funding, perhaps in part because the newly implemented 1966 agreement between the Army and U.S. Air Force mandated that the Army give up all fixed-wing tactical airlift capabilities in exchange for unrestricted development and acquisition of rotary-wing assets. TAB’s primary customer was now obliged to go with the UH-1 and CH-47. The end result was the coming of age of the helicopter-borne air-mobile Army during combat operations in the Vietnam War.

Kristi Harding contributed to this article.

For further reading on Project AGILE, go to: http://en.wikipedia.org/wiki/Project_AGILE

A look into the scope of Project AGILE can be found in this July to December 1963 semiannual report by ARPA, including Subproject III to which TAB was tailored: http://www.nal.usda.gov/speccoll/findaids/agentorange/text/00340.pdf

A review of the Army/Air Force 1966 agreement can be found here: http://en.wikipedia.org/wiki/Johnson-McConnell_agreement_of_1966

Photo Captions

100_0001_rlw: The TAB proposal brochure included this artist’s conception of the vehicle in a scenario that showcased all three modes. Boat operations could take place on rivers, estuaries, coastal areas, lakes and, revealingly, rice paddies. Clearly Southeast Asian environments were in mind. Image credit: Tony Chong collection
img662: This 3-view shows the basic dimensions of the vehicle. Note the split inlet on the nacelle for the twin P&W PT6-B15 turboprop engines. As a point of reference, Northrop Grumman’s new X-47B UCAS-D is a couple of feet greater in span and about a foot shorter in length than the proposed TAB. Image credit: Tony Chong collection
img665w: All three modes of transportation are shown in this image. The stowed wings would have shielded the shrouded prop, possibly dampening the noise for bystanders. Image credit: Tony Chong collection
img666w: The wing and tail folding operations appear to be simple and straightforward, a plus for use by draftees in rough conditions. Image credit: Tony Chong collection
img675w: This detailed view, with cross-sections, shows the catamaran hull design of the TAB. Image credit: Tony Chong collection
img676w: The cockpit would have been a fairly basic affair. Instrumentation was only installed on the “driver’s” side even though a second wheel was provided for the right seat. Image credit: Tony Chong collection
img667w: TAB was designed to fit inside the Lockheed C-130 Hercules, albeit rather snuggly. Note the Hercules outline is of the early C-130A “Roman-nose” configuration. Image credit: Tony Chong collection
img670w: The projected aircraft performance specs were very modest compared to other fixed wing aircraft, and even to some helicopters. Obviously the selling point was the versatility of the land and water options. Image credit: Tony Chong collection
img673w: Projected truck performance was better, despite a top speed of only 50 mph and the ungainly addition of large exposed surfaces from the stowed wings. One wonders how vehicle mobility would have been affected by this, much less their susceptibility to road damage and small arms fire. Image credit: Tony Chong
img671w: Water performance would be rather good, all things considered, especially in speed. Note the sea state operations/survivability figures. Image credit: Tony Chong collection
Northrop TAB bw: Old Polaroid photos found in the Display Model Shop archives show a rather nicely detailed scale model of the TAB in profile with cargo ramp down. The angle of the nacelle and shroud is more pronounced in the model than in the 3-view, suggesting a different design iteration. Photo credit: Northrop Grumman Display Model Shop
Northrop TAB cw: Another Polaroid showing a high-angle view of TAB. The size of the model is apparent when seen with the tabletop. Photo credit: Northrop Grumman Display Model Shop
TAB model lf frt: This appears to be a studio shot of the TAB model with the wings and tail folded into the stowed position. The shrouded propeller is effectively shielded by the wings. They also appear to channel airflow to the prop. Ground and water operations would seem to be similar to Airboat vehicles. Since TAB was supposed to be able to handle 45% longitudinal slopes on a hard surface, propulsion via prop would’ve been interesting to see in those conditions. Photo credit: Tony Chong collection
TAB model lf rr: The TAB cargo bay was designed to hold either a standard Jeep, Army Mule, M-102 105mm Howitzer or other like equipment. The model shows two such payload options. Photo credit: Tony Chong collection
Northrop RC cw: Northrop authorized a Radio Control (RC) model for concept testing. This is a shot of a straight-tail version under construction. Note the catamaran hull and wood body. Photo credit: Northrop Grumman Display Model Shop
14060-104Aw: It is unclear if only one RC model was made or if there were more than one. This image shows a variant with a pronounced dihedral to the tail. There are endplates to the tail as well and a tricycle-type landing gear arrangement. The propeller shroud also appears different in configuration, although that may be an illusion due to the large side support structure of the model. Note the size compared to the cameraman. Photo credit: Northrop Grumman
14063-104Bw: This photo shows the model taking off for a flight. It is unknown how many flight were made, or where. It does not appear to be Hawthorne. One thought is that it might be the old Rancho Conejo Airport, where the former Northrop Ventura Division facility was located near the southern end of the runway in Newbury Park, CA. Photo credit: Northrop Grumman