Republic Seabee Dissected!

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N36WT

N36WT (s/n 1054)
26 July 2004
Photo: © M&A via Maverick Yamamoto
  

When the Republic Seabee amphibian was put into production in 1946, this was the result of a design and development process never seen before in the aviation history.  For the first time an aircraft manufacturer seriously looked to the automobile industry to take advantage of automotive design and manufacturing methods for reducing production time and costs. The first Seabee prototype, the RC-1 Thunderbolt Amphibian NX41816, was a concept demonstrator made by conventional aviation construction methods. First flight was made on 30 November 1944.

However, Republic Aviation's president Alfred Marchev, realized that if Republic was going to win the expected post WW2 personal airplane market boom, they had to make something different at a price affordable for the masses.  Marchev ordered a complete redesign of the Seabee to reduce the cost dramatically.  The seemingly impossible goals Marchev set for his engineers were:  a four seat amphibian aircraft at a sales price of $ 3.500 - the conventional prototype would have an estimated sales price of $ 13.000!

The engineers took the challenge.  Several changes were made;  the tapered cantilever wings were replaced by constant chord strut braced wings, the partly buried retractable wheels of the RC-1 were replaced by wheel retracted in the free air.  Number of parts were reduced substantially by introducing deep die press forming methods from the automotive industry, and wherever possible automotive parts and components were used in favor of overpriced aviation industry parts.  In order to reduce the costs of the engine installed, Republic even acquired the engine manufacturer. Republic also negotiated large quantity rebates from the vendors.

Unfortunately, several factors made big problem for the Seabee production and sales. Important manufacturing tools such as sheet metal presses got delayed from the tool subcontractors, material and labor costs increased forcing Republic to increase sales price twice in less than a year.  Production deliveries got delayed and production rates were never even close to the original goal of making 400 Seabees per month - 5.000 in one year. In June 1947 Republic was forced to stop production when sales failed, after only one and a half year and 1060 built.  On 2 October 1947 Republic announced that the Board had made the final decision to terminate the Seabee project in favor of military aircraft such as the new F-84 Thunderjet fighter jet.

N36WT (s/n 1054)
Arriviving at Munro & Associates
Troy, Michigan
15 March 2004
Photo: © M&A via Maverick Yamamoto

Then - more than a half a century later - NASA started to look into the future transportation systems.  It is realized that in the future it might be necessary to transfer more of the personal transportation from the roads to the air, to avoid further congestions.  NASA initiated a number of projects to develop Singe Engine Propeller aircraft for future personal use - the Personal Air Vehicle (PAV) concept.   Three factors were identified as the main barriers preventing widespread adoption of SEP aircraft for personal transportation; (1) Ease of Use (2) Pollution and (3) Cost.  NASA research projects were started to research possible solutions to overcome all these barriers.

Cost was ranked as the third most important of all of the barriers preventing widespread adoption of SEP aircraft for personal transportation. This is because it is the other measure that ultimately determines value and also determines the actual size of the market. Mode choices that are low cost, but of little value or are high value but high cost are both limited in total market size. Even if the EoU and Pollution PAV priorities increase the utility of the SEP aircraft, the cost is much too high for a new, invigorated market to take off. Kraus noted that cost cutting of up to 20% during the 1980s had very little effect on sales. What is needed is a rebalancing of design priorities in favor of radical reductions in cost at much higher levels of production, keeping in mind that the market will have to bootstrap itself up, meaning that there has to be a path from relatively low rates of production through to historically high rates of production.

Since the PAV sector intended to address cost through design, it was necessary to first determine where the major cost items were and then propose approaches to address them.

It is immediately obvious that labor and engine account for nearly 50% of the price, that profit accounts for 25%, and that incidentals account for about 15%. Since price reductions of 20% are ineffective, and both profit and incidentals cannot be affected by design, the only option was to make radical cuts in labor and engine costs.

Labor Cost - A survey of historical best practices in aircraft production brought to NASA's attention the construction and production methods that Republic Aviation used on their RC-3 Seabee model. Most aircraft manufacturers believed that there would be unprecedented increased civilian demand and the normal dramatic drop in military demand for aircraft after World War II ended. After having produced more P-47 Thunderbolts than any other American fighter type (15,686), Republic was in possession of a wealth of production time and material cost data, so a small group of engineers analyzed this data to see where cost could be taken out. They quickly realized that building a civilian aircraft the way that they currently did was going to be prohibitively expensive, so they decided to use a radical construction method proposed by Alfred Boyajian that used deeply formed, heavy gage skins with few internal parts. Nearly all of the internal structure was replaced by deeply formed skins, and all fastening was accessible by semiautomatic riveting guns from the outside.

This was a complete departure from the conventional construction of many interlocking internal parts that required hand assembly, usually with poor access for fastening . Republic’s attention went well beyond simply reducing part count and fastening accessibility. They realized that operations, like heat treating, assembly, disassembly, deburring, reassembly, and manual multi-operation tooling reduced productivity unacceptably and unnecessarily. They compromised the structural material strength for better formability without any post treatment operations. They used semi-automatic riveting guns that clamped and punched holes in parts before upsetting the rivets instead of drilling so that disassembly and deburring and reassembly operations would be eliminated. They even designed and built their own automated wing assembly machine that was able to fasten the wing primary structure together in minutes.

While the greatest impact of this philosophy was felt on the flying surfaces, as much of it as possible was also applied to the fuselage, yielding large cost reductions there as well. All of this attention to detail and design for automated assembly yielded an overall airframe part reduction of 75% and a labor reduction of 92% with an increase in tooling cost of 100%.

Republic found that for simplified design and aircraft tooling, there is an immediate 38% cost reduction due to the lower part count, compared to conventional design and aircraft tooling.  However, when comparing the airframe cost per pound as a function of units produced, the slope of the curve is essentially the same. This means that the increased productivity with increasing units is limited by the aircraft tooling.

The lowest curve is for the simplified design and automotive type tooling. While there is an immediate increase of 25% in cost because of the increased tooling cost, the curve is on a completely different slope, paying off dramatically in productivity as units increase. It is this improved learning curve that holds the most promise for reducing PAV costs. There are two more important points to be made about these curves. First, even at only 100 units per year, the simplified design with automotive tooling is lower cost than the conventional design. Second, the increased tooling costs are more than made up for by productivity at approximately 150 units per year.

While this is a lot of units for most manufacturers in today’s market, this low rate needed for breakeven makes bootstrapping the market very plausible.

The NASA PAV sector adopted the Republic Aviation philosophy as a baseline, and worked with others to verify these assumptions. Munro and Associates, experts in lean design for the automotive industry, has been branching out into the aviation industry. They were funded to perform the same disassembly and cost analysis for the Republic Seabee that they do for major automotive manufacturers. Much to their surprise, they were very impressed with the Seabee design. They did have constructive input on potential improvements, particularly with respect to modern fastening options like laser weld bonding and friction stir welding, but the overall philosophy and implementation was judged excellent. Munro came to the conclusion that the sale price for this fairly high performance aircraft would be about $100,000, with standard avionics, at production rates of 4000 units per year. If true, this would be an excellent value and leave a large budget for those willing to upgrade to the NFD and H-mode avionics.

You can learn more about PAVs at http://cafefoundation.org

N36WT (s/n 1054)
at Munro & Associates
Troy, Michigan
16 March 2004
Photo: © M&A via Maverick Yamamoto

MISATS – The Michigan Small Aircraft Transportation System is a non-profit, government-industry-university consortium formed to transfer select commercial and automotive technologies to general aviation applications. Once developed, these technologies will be integrated into the SATS national research program.  Innovations developed by MISATS will be eligible for commercialization by private companies with competitive business models. These companies will then be positioned for leadership in a revitalized and a commercially viable general aviation industry.

MISATS is a contributor to the long-term NASA SATS vision of a National personal air transportation system that is safer and more efficient than the current commercial air travel system. SATS is a long range national vision with objective spanning out 25 years. The NASA goal is to reduce inter-city travel times by half in 10 years, and by two-thirds in 25 years.

NASAs strategy for general aviation revitalizations of aviation industry is challenging. The plans calls for the delivery of up to 20000 aircraft in 20 years, with some very demanding parameters. Aircraft price and cost of operation must be slashed dramatically, but improve performance and safety and vastly simplifying their operation.

Munro & Associates started MISATS with the NASA approved goal to demonstrate that automotive style systems integration, Six Sigma quality, Lean Design and lean manufacturing can radically reduce aircraft complexity, while revolutionizing safety, efficiency and affordability.

MISATS operates under the long term objectives that; aircraft can be designed and manufactured at unit cost comparable to automobiles.

Select technologies can be common between automobiles and general aviation aircraft.

The innovations and technologies being developed by MISATS are aimed at small aircraft private and business commercial smaller airports around the country.

MISATS is the only SATS program working to improve  the viability of the general aviation business model through aircraft design, manufacturing, training and infrastructure.

Ultimately, MISATS plans are launching a compelling three year air vehicle design and fabrication program. The goal is to build a flying demonstrator that with the transition into a business venture that can provide these vehicles to the nation.

N36WT (s/n 1054)
at Munro & Associates
Troy, Michigan
18 March 2004
Photo: © M&A via Maverick Yamamoto

N36WT (s/n 1054)
Munro & Associates; Troy, MI, USA.
March 2004
Photo: © M&A via Maverick Yamamoto

N36WT (s/n 1054)
at Munro & Associates
Troy, Michigan
14 July 2004
Photo: © M&A via Maverick Yamamoto

Thank you very much, M&A and Maverick Yamamoto, for supplying this story and the great images of Seabee s/1054 dissected!

 

THE VIDEO!

 

 
by Munro & Associates

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Updated: 2010-11-22

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