boeing model 40 maildelivery airplane

8/9/2019 Boeing Model 40 Maildelivery Airplane

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The History of the Boeing Model 40

A Contribution to Corporate and Air Line Growth

45th

AIAA Aerospace Sciences Meeting and Exhibit

January 7-10, 2008Grand Serra Resort HotelReno, Nevada

Mike Lavelle,Associate Fellow AIAAFellow, Royal Aeronautical SocietyMuseum of Flight

Seattle, Washington

Boeing Historical ArchivesBoeing Historical Archives


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Dedication

This paper is dedicated to Mr. William E. Boeing Jr. for his stewardship andcontinuous support of aviation/aerospace education.

Author and Mr. William E. Boeing Jr. Boeing Model 40B Roll OutWenatchee, WA. October 6, 2007

This paper is copy write by author and The American Institute of Aeronautics and Astronautics 2008


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Acknowledgements

This paper has been supported in one way or another by many people withwhom I work. I like to thank them all for their time, assistance and feedback they

provided while the paper was in the process of being researched and written.

The Museum of Flight Staff

Alison Bailey - Associate Director of Development Museum of Flight Andrew Boike - Annual Fund Coordinator Museum of Flight Meredith Downs Photo Archivist Museum of Flight John Little Exhibits Technician and Aviation Historian Ernst Marris Security Officer Museum of Flight Dennis Parks Director of Collections Museum of Flight Katherine Williams Archivist Dahlberg Center for Military Aviation

History, Museum of Flight

The Boeing Company Archives Staff

Mike Lombardi - The Boeing Company Corporate Historian Tom Lubbesmeyer Boeing Historian \Archivist

Museum of Flight Trustee

Brien S. Wygle Retired Boeing Vice President and Company Test Pilot

I would especially like to thank Andrew Boike and Brien Wygle who spent their

own time helping with the papers editing and format.



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Outline

The History of the Boeing Model 40A Contribution to Corporate and Air Line Growth

Introduction and Backgroundo Overview Post Office Operations until 1923o Early Aircraft usedo Need for Updated equipment

The Contenders for the de Havilland DH-4 Replacemento The industry responseo Boeing Model 40 Overall Performanceo Boeings Design approach

Establishing the Industryo Events leading to Model 40 redesigno The Pratt & Whitney Aircraft Company

Bringing the Boeing Model 40A into Production o Key events and Activitieso The Boeing Model 40 Line Operationso United Aircraft and Transportation Corporationo How many were built and What Model 40 is it

Where are they now The Boeing Model 40 survivors and

replicas.

Pictures of the constructions of The Museum of Flight Model40 replica under construction.

Summary and conclusion.

References

About the Author



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The History of the Boeing Model 40

Introduction and Background

Overview of Post Office Operations until 1923

Aviation historian called 1919 the First Year of Air Transportation. That yearmarked the advent of the postwar passenger-carrying airplane; it was bornamidst the glut of surplus wartime airplanes from all the combatants air arms.Within two months of the armistice, on January 8, 1919, Germany authorizedairline development. The first German airline was the Deutsche Luft Reederei(D.L.R.), which opened passenger service between Berlin and Weimar, viaLeipzig with war-surplus A.E.G. and D.F.W. biplanes. While in France, theFarman Brothers, well known aircraft designers before and during World War Iopened scheduled service between Paris and Brussels using the Farman F.60

Goliath (figure 1a) in March of 1919. The British soon followed in August of 1919when Aircraft Transport and Travel Ltd flew a modified D.H. 4A,(figure 1b) fromLondon to Paris carrying cargo and one passenger initiating the first scheduledinternational air service. (Hallion 1977 p8) As we shall see the DH-4 also playeda major role in the U.S. air transportation system with the U.S Postal Air Service.

Kenneth Munson Illustration Farman F.60 Goliath (1a)

de Havilland D.H. 4A (1b)

Figure 1

In the United States the development of schedule commercial aviation did notstart with passenger service as in Europe but was tied closely with the efforts ofthe United States Post Office. When the US Army began flying the mail from New


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York to Washington D.C with Philadelphia as an intermediate stop in May of1918, few realized that within less than two and half years this nascent 215-mileroute would grow into a 3000 mile transcontinental air mail line. The initial forceand credit behind this growth was Assistant Postmaster General Otto Praegerwho by August of 1918 transitioned Army mail flights to civilian Post Office

operations. Praeger, a self-taught former Washington D.C. correspondent fromTexas was a demanding chief. During the summer of 1918, he appointedpersonnel to key management positions. One such person was CaptainBenjamin Lipsner who resigned from the Army to become the firstSuperintendent of the Air Mail. Lipsner in turn hired qualified pilots, selectedaircraft, and established logistical support along the Post Offices route structure.

During the first year of operations, the Post Office realized an operational profit of$19,000. Postal revenues for the year totaled $162,000, while the cost to fly themail was $143,000. The initial year of operations would be the only time that theairmail service generated a profit.

Early Aircraft Used

Post Office Air Mail Routes 1918-1921From R.E.G. Davies Airlines of the United States Since 1914

Figure 2


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However, this is understandable given the swift route expansions illustrated byFigure 2. During this growth period, the Post Office was trying to find theoptimum aircraft for the route as the line expanded west. The Post Office utilizedmostly World War I surplus aircraft that included the Curtiss JN-4H and, Armysurplus de Havilland DH-4s. There was also a mix of new post war aircraft. Such

as the seven Standard Aircraft Companys JR-1Bs (figure 3a) and a new postWorld War I design, the all-metal German Junkers JL-6. (figure 3b).

www.postalmuseum.si.edu

Standard Aircraft Company JR-1B (3a)

www.postalmuseum.si.edu All-Metal Junker JL-6 (3b)

Figure 3

As a point of interest the Standards were the first non-military aircraft the U.S.Government purchased for $3500 each. They had 150 H.P. Hispanso-Suizaengines and could climb to 6000 feet faster than the Curtiss Jenny JN-4Hs. Thiswould be an important performance consideration along the mountainoussections of the route.

Early in fiscal year 1921 the Post Office paid aircraft manufactures $476,000 fornew and modified aircraft. However, when they could not find the ideal aircraft for
http://www.postalmuseum.si.edu/http://www.postalmuseum.si.edu/http://www.postalmuseum.si.edu/http://www.postalmuseum.si.edu/


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their operational needs they selected what was considered to be best of whatthey had and began a program of standardization.

The specific reasons for retiring these aircraft varied but generally included oneor more of the following reasons, high cost of maintenance, safety, efficiency

and/or overall aircraft performance. Figure 4 lists the aircraft types phased out.

Aircraft Phased out

7 Curtiss JN-4Hs 3 Glenn Martin Mailplanes 7 Standard JR-1Bs 4 Junker JL 6s (F-13) 17 Curtiss R-4ls 1 L,W.F. Type V 20 Twin DHs 2 Curtiss H-as

Figure 4

de Havilland DH-4

Figure 5

Although a World War I British design the de Havilland DH-4 (figure 5) emergedfrom this pack of mixed aircraft a reliable work horse along the transcontinentalroute until the Post Office would turn their routes over to industry contractors atthe beginning in 1926.

During World War I the DH-4 was built for the Army Air Service by the Dayton-Wright Aircraft Company under license agreement from the Airco consortium ofGreat Britain. The American version of the aircraft was powered by a 12 cylinder400 HP Liberty Engine. After World War I the Army Air Service had several

Boeing Historical Archives


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aircraft manufactures modernize the DH-4 airframe. For example, Boeingmodernized one hundred airframes between March 6 and July 1, 1920 byrepositioning the fuel tanks and pilots cockpit. This improved the safety of flightin the event of an engine fire. Additionally, the landing gear was also movedforward slightly to improve ground handling. In 1923 Boeing further improved DH-

4s by converting several airframes from wood to steel. Intended primarily for theArmy, many of the modernized (DH-4Ms) were transferred to the Post Office,remaining in service until it ceased flying the mail in 1927.

By mid-1924, using primarily the DH-4, regularly scheduled transcontinental mailservice became a reality. In addition, to day flights, the Post Office pilots beganregular night flights. They were guided by a lighted airway system with rotatingbeacons and brightly lit emergency landing fields, timing their night flying to reachthe end of the lighted airway by daybreak. The Post Office resumed using specialairmail postage, which it had discontinued in 1919. By 1924 Airmail now costeight cents to travel in any of the three zones comprising the transcontinental

route and could travel across the country for 24 cents. By the end of 1924,airmail planes were routinely completing the New York to San Francisco routewithin 34 hours.

Need for Updated Equipment

On April 7, 1924 realizing the need to replace the aging DH-4 fleet, the PostOffice requested proposals from interested companies for an aircraft based onthe following specifications:

Liberty Motor

Cruising Speed at least 95 M.P.H. Landing Speed 50 M.P.H. or less Service Ceiling 15,000ft. Pay load (mail) not less than 1000 pounds Cargo space not less than 50 cubic feet Fuel - cruising range 450 miles

Other requirements included: crash-proof gasoline tanks conforming to Armyspecifications, seat type to accommodate a parachute worn by the pilot, and astatement of materials and unit stresses to be used in the construction of primary

structural parts. Other provisions specified that the design had to be easy toproduce, allow rapid replacement of engine or other components while beingmechanically simple to maintain. (Boeing Historical Archives)

At the time, the major Post Office requirement specified the aircraft needed touse the well-proven and somewhat reliable Liberty 400 HP engine. Thisrequirement had at the time sound rational behind it.


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The Liberty 12-cylinder water-cooled engine was America's greatesttechnological contribution to aircraft design and development during WWI (figure6). Rated between 400-450 hp, it weighed only two pounds per horsepower, farsurpassing similar types of engines mass-produced by England, France, Italy,and Germany at that time. During the war, Packard, Lincoln, Ford, General

Motors, Nordyke, and Marmon produced 20,478 Liberty 12s. They were usedprimarily in U.S.-built D.H.4s. With the Post Office, operating DH-4s along theirroutes the pilots and maintenance personnel had extensive operationalexperience with their performance, maintenance and idiosyncrasies.

Additionally, the Post Office Department had over two hundred Liberty 12engines with associated spare parts in their inventory.

Liberty 12 In For MaintenanceFigure 6

Since the new air-cooled radial engines in design with The Wright Company andPratt & Whitney were not yet fully developed, the Liberty was the logical engineof choice for the Post Offices objective of developing a reliable airmail plane(Smith 1981 p111-112). The goal at this point was not to advance new aircraftdevelopment as much as improve bottom-line cost and low risk investment.While at the same time they would be expanding the mail service routes withreliability and consistent operations. Consequently, the Liberty enginerequirement produced from the aircraft manufactures who offered aircraft for PostOffice evaluation similar performance numbers as indicate for three aircraftcompanies listed in figure 8.

During the same time frame, there was pressure from Congress to reduce thecost of flying the mail by turning the routes over to private contactors. Thepassage of the 1925 Air Mail Act (Kelly Act) brought that concept into reality.However before the 1925 Air Mail Act came into effect several manufacturessubmitted designs to the Post Office for evaluation.



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The Contenders for the de Havilland DH-4 Replacement

The Industry Response

Bids were submitted to the Post Office purchasing Agent in Washington, D.C. on

July 15, 1925. Eleven aircraft manufactures (figure 7) tendered design proposalswith cost breakdowns for aircraft produced in lots of three to fifty. (BoeingHistorical Archives). The aircraft companies submitting proposals are listed infigure 7.

The Douglas Co. Santa Monica, Calif.The Boeing Airplane Co. Seattle WashingtonThe Kurz-Kacch Co. Dayton Ohio.

Aerial Service Corp. Hammondsport, N.Y.Lawson Aircraft Co. Inc. New York CityHuff Daland & Co. Ogdensburg, N.Y,

Curtiss Aeroplane & Motor Co. Garden City N.Y.Cox-Klemin Aircraft Corp. Baldwin, Long IslandConsolidated Aircraft Corp. Buffalo, N.Y.G.Elias & Bro., Inc Buffalo, N.Y.Sikorsky Aero Engineering Corp New York City

Post Office - De Havilland DH-4 Aircraft Replacement BiddersFigure 7

.The Boeing Airplane Company entered the Model 40 Mailplane prototype in thecompetition. Other manufactures in the competition that provided aircraft forevaluation included Douglas Aircraft, of Santa Monica, California with their M-1

Mailplane and Curtiss Aeroplane and Motor Company of Garden City, New Yorkwith their first commercial aircraft since 1919 called the Carrier Pigeon. (Bower,1979). Of course no one knew it at the time but this would be the first of manycompetitive commercial aircraft product battles between Boeing and Douglasthey would have against each other over the next 72 years until they merged in1997.

Boeing Model 40 Overall Performance

Figure 8 shows the three main aircraft three contenders the Post Officeevaluated along the air mail route structure to replace the DH-4. The winning

design had the potential for a production order of 50 aircraft or more. TheDouglas proposal for a production lot of three aircraft was $16,500 per aircraftdecreasing to $12,500 per aircraft for a lot order of 50. The Boeing AirplaneCompany was $23,000 per example for three aircraft and $11,000 per aircraft for50. The highest bidder was Sikorsky Engineering Corporation coming in at$27,000 per aircraft for a lot of three. The low bidder was the Kurz-Kacch Co.with $8,000 for a lot of three aircraft. (Boeing Historical Archives) It is interestingto note when reviewing figure 7 above that of the eleven companies submitting


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bids eight were from New York State, mostly from the New York City area.Clearly, one could conclude the geographic center of aircraft engineering andmanufacturing during the 1920s in the United States was on the east coast.Eventually, with Douglas and Boeing established on the west coast they wouldwith the help others, such as, North American and Consolidated Aircraft shift

aircraft engineering and manufacturing to west coast of the Untied States by1945.

Boeing Model 40 Douglas DAM-1 Curtiss Carrier Pigeon

Aircraf t Boeing Model 40 Douglas M-1Curtiss CarrierPigeon

First Flight 7-Jul-25 6-Jul-25# Produced Prototype Prototype

Pilot & Pax Pilot Only Pilot / 2 Optional Pax Pilot

Powerplant Liberty 400 h.p. Liberty 400 h.p. Liberty 400 h.p.

Wing Span 44'2" 39'8" 41"11"

Length 33'2" 28'11" 28" 9.5"

Height 12'3" 10'1" 12"1"

Empty Weight 3,425 lbs 2,885lbs 3603 lbs

Gross Weight 5,495 lbs 4,775" 5620 lbs

Speed 135 m.p.h 145 m.p.h. 125 m.p.h.

Range 700 miles 600 miles 525 miles

ceiling 15,800' 17,000' 12,800'

Basic Specifications of aircraft evaluated by the Post Office 1925Figure 8

When one studies the overall dimensions and performance numbers of thesethree aircraft evaluated by the Post Office, few apparent differences stands outbetween them. Even when looking at the three basic performance numbers of hespeed, range and useful load, in figure 9, the numbers again are similar but twoof the categories favor the Boeing Model 40 by slight margins.


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0

1000

2000

3000

4000

5000

6000

Boeing Model 40 Douglas M-1 Curtiss Carrier Piegon

Boeing Model 40 113 700 5495 3425 2070

Douglas M-1 118 600 4775 2885 1690

Curtiss Carrier Piegon 105 525 5620 3603 2017

Speed mphRange

miles

Gross

Weight lbs

Empty

Weight lbs

Useful

Load lbs

Basic Performance Comparison 1925 Mailplanes

Figure 9

For a while, during the evaluation period the Curtiss Carrier Pigeon seemed to bethe front-runner of the three. (Leary, 1985) That changed when Post Office Pilot

Arthur R. Smith left Chicago for Bryan, Ohio on the night of February 12, 1926.Shortly after 10 PM Smith crashed into the woods after hitting a tree nearMontpelier, Ohio just six miles from Bryan. The crash was fatal for Smith. Thecause of the accident was thought to be weather related even though there was

a 1000-foot ceiling. (Leary 1985-p232). Most-likely, it was another case of lowlevel flying in marginal weather condition at night. But as a result, Curtiss did notreceive any follow on orders from the Post Office. Nor was the Boeing AirplaneCompany with their Model 40 prototype selected for additional orders.

The evaluative phase for the Post Office aircraft selection was largely informaland based mostly on pilots comments, input and pilot reports of Post Officepilots flying the prototypes on the mail routes.

Douglas Aircraft Company at the time had an excellent reputation in the aircraftindustry with their military aircraft observation planes. Many of the Post Office

pilots were Reserve Army Aviators and had flown the Douglas O-2B observationaircraft on which Douglas based their M-1 mailplane design. (Francillion, 1979).The Douglas M-1 mailplane also featured welcome innovations such as brakesand a tail wheel instead of a tail skid as on the other two aircraft (Leary 1985 -p232). The 1000lbs mail load could be carried at a cruise speed 118 mph whilelanding at 52 mph. Additionally, two of the four Douglas World Cruisers (DWC)had completed a around the World flight in 1924. The positive image of the


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successful Around the World Flight reinforced the image of Douglas as an up andcoming firm that designed and built excellent aircraft.

Based upon the recommendations from the mail pilots, the Postmaster Generalordered 40 planes from Douglas Aircraft at $11,900 each. Later as the Air Mail

Service was transitioning their routes to private contractors under the 1925 AirMail Act (Kelly Act), it would order an additional 11 aircraft. (Leary 1985 - 233)

Boeings Design Approach

The Boeing Company of Seattle will have a hundred years of history in 2016.However, when it established itself as Pacific Aero Products on July 15, 1916 itwas a small firm with only 21 employees. The named was changed on April 26,1917 to Boeing Airplane Company and has been Boeing in one form or anotherever since. (Bowers 1966 p34) From the end of World War I, in November of

1918, to the time of the design of the Model 40, Boeing managed to survive onaircraft modernization contracts for the government, that included the deHavilland DH-4 as describe previously, and building new airplanes designed bythe Army Air Service Engineering Division based at McCook Field Dayton, Ohio.

An example of the survival activity that Boeing was involved with was the GA-1project. Boeing was the successful bidder to build to 20 (later reduce to 10)Ground Attack -1 (GA-1) that the Army had designed. This aircraft design wasbased on the experience of World War I trench warfare. First flown in May of1921 the GA-1 had many design issues that included being extremelyoverweight, with poor aerodynamics and engine cooling. Nevertheless Boeingdelivered all 10 aircraft to the Army. The experience did provide Boeing theopportunity to learn production methods for aircraft assembly, engineering designprocesses for aircraft performance improvement methods which would paydividend in the later 1920s.

The first non-military airplane designed and built by Boeing since 1920 was theModel 40 prototype in response to the Post Offices request for bids to replace theDH-4 .On April 7, 1924 E.N. Gott President of the Boeing Airplane Companyauthorized the Chief Engineer Claire L. Egtvedt and his team to proceed with theplanning to respond to the Post Office request along the lines discussed in ameeting the pervious day with Mr. William E. Boeing. (Boeing Historical Achieves170-2)


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Model 40 Profile and Frontal View

Figure 10

The aircraft that was designed had conventional wooden spars and ribconstruction with fabric covering. The overall length of the wing span, for both theupper and lower wings, was 44 2.25 inches. The wing span dimensions wouldremain unchanged with all subsequent Model 40s. The Fuselage length as seenin the profile drawing (figure 10) was 332.25. The fuselage used laminatedveneer wood over wood formers when at the time aircraft designers including

Boeing were converting to steel tubing for the fuselage structures. Why Boeingselected this method of construction over steel can only be speculated since nodocument has surfaced at this time. I would assume it was a matter of the timeand cost to build welding jigs when they had skilled resources to design and buildthe wooden structure prototype to meet the Post Office deadline. Later in 1932 aBoeing production manager remarked it cost three times as much to build ametal aircraft as a wooden one.



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The wood veneer covering the fuselage had the grain running at a 45 degreeangle to the axis of the fuselage as seen in figure 11a and 11b below.

Model 40 Wood Veneer Covered Fuselage (11a)

Veneer Fuselage of Model 40 with Liberty Engine (11b)Figure 11

There was also an unusual feature with the upper wing configuration. The rightwing fastened to the cabane struts above the fuselage, but projected slightly tothe left of centerline to the point where the left wing joined the right. (Bower 1989p125) This offset can be clearly seen in the drawing of the Model 40B.(Figure 19).

There were four ailerons, all without balance in each wing. With the upper andlower ailerons connected by a pair or wires. The Model 40 made its first flight on




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July 7, 1925. Flight test determined that the fuselage was a little short fordirectional stability. A modification was engineered to lengthen the fuselage tocorrect the problem by adding a steel frame extension at the tail. In figure 12 a, band c below one can readily see the effects of this modification on the Model 40prototype appearance.

Profile Model 40 prior to Fuselage Extension (12a)

Model 40 Fuselage extensionModel 40 Fuselage extension modification (12b)





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Profile Model 40 with Rear Fuselage extension Covered (12c)

Figure 12

Post Office records show the Boeing Model 40 (Boeing C/n: 775) was purchasedand put into service February 10, 1926 on the ClevelandChicago route. (BoeingHistorical Archives - file 604) The flight performance seemed to be satisfactoryand was reported as such by a Post Office Pilot flight report filed by C. EugeneJohnson to F. E. Caldwell Acting Superintend of the Western Division route onFebruary 26, 1926. (Boeing Historical Archives Post Office Letter Dated February26, 1926)

Johnson documented his impressions on a flight from Concord California toMaywood Illinois prior to putting the Model 40 into service on the Cleveland Chicago route. He reported on the taxing, take-off, landing, stability,maneuverability and visibility charteristics of the Model 40. Johnson reportedmostly positive comments with the exception being the visibility. He said, Thiscould be improved and most of the fault lies in arrangement of the windshield,size and shape of pit opening (cockpit). At present, it takes considerable strainingand stretching for hedge-hopping work, of which was done through Illinois.(Boeing Historical Archives Post Office Letter Dated February 26, 1926)

What is telling about the comment Johnson made is the type of flying that wasbeing done along the mail routes especially with poor visibility due to adverseweather. That in itself was a major factor contributing to the death of 32 of theoriginal 40 Post Office pilot having fatal accident while flying the mail. Obviously,visibility was a major safety concern but flying low was not the solution.

However, the mechanical performance of the Model 40 did not receive favorablereports either. Apparently the cooling radiator for the Liberty 12 engine hadseveral leaks. In over 187 hours of operation between February 26 and June 20,1926 the Model 40 had to be taken off the line 10 times for repairs. Additionally,several large cracks and splits in the veneer fuselage were found duringinspections. They revealed that the cracks, splits and tears were mainly localized



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about the two front upper fittings which, with corresponding lower fittingssupported the engine nacelle where they received loads due the reaction of thepropeller torque, (twisting force) the thrust of propeller and the weight of theengine. The impacts from landing also contributed to the; cracks by the forcesgear being transmitted through the gear, fuselage and engine mounts.(Figure 13)

The result of this inspection determined the Model 40 had to be withdrawn fromservice on June 22, 1926 until modification and repairs were made. (BoeingHistorical Archives Post Office Letter Dated July 20, 1926) This added to thefactors why the Model 40 was not considered for a follow on orders from the PostOffice at the conclusion of their evaluation period, when orders were placed forthe Douglas Mailplane.

Area which fuselage cracks appeared on Model 40Figure 13

Although, the Boeing Airplane Company did not win the initial competition for theD.H. 4 it was not the end of the Boeing Model 40. The following will describe theModel 40 rebirth and engineering along with the contribution it made towardsfacilitating corporate aviation growth in the turbulent years ahead.

Establishing the Industry

Events leading to Boeing Model 40 redesign

With the announcement that the Douglas M-1 mailplane was the winner of thePost Office contract to replace the Departments aircraft and Douglas Aircraftwould receive follow-on orders for additional planes. Boeing filed away all of theirdesign drawings, not realizing they would be pulled from the file within 18 monthsto re-engineer the Model 40 mailplane. The Boeing Airplane Company would



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redesign the aircraft in order to submit a bid for the Chicago to San Franciscoportion of the transcontinental air mail line.

Since the Wright Brothers developed and publicly demonstrated the firstpractical aircraft to the U.S Army at Fort Myers Virgin (Orville) and Le Mans

France (Wilbur) in 1908 it is strange the United States should lag so far behindother countries aviation industries prior to and after World War I. After the GreatWar three main elements in the United States kept the aircraft industry alive andin front of the public. The three were the Military, with demonstration flights, suchas, the Navys 1919 NC flights across the Atlantic and the Armys 1924 aroundthe World Flight with two of the four Douglas World Cruisers completing theattempt. The second were the Barnstormers who with surplus aircraft from thewar gave thousands of Americans their introduction to going aloft. And finally thePost Office with the successful effort of establishing the transcontinental air mailline.

However, none of these had any established infrastructure, regulations orstandard operating procedures guiding them prior to the United States enteringWorld War I. The National Advisory Committee for Aeronautics (NACA) wasestablished on March 3, 1915. Although the NACA rapidly became anindependent agency little was accomplished due to public and governmentapathy toward the aviation industry. Shortly after the World War I PresidentWilson submitted a Bill to Congress drafted by the NACA that would authorizethe Department of Commerce to license pilot, Inspect aircraft and operateaerodromes (airports) but the apathy continued and no legislation was passed. Inthe interim 26 States passed what was to be called the Uniform Aeronautics Actwhich was regulatory in nature but hardly uniform and rarely enforced. (Hallion,1977)

Ironically it would be the railroad industry that would be the catalyst thataccelerated the legislation and infrastructure so badly needed in aviation to movebeyond the level of a hand to mouth aircraft industry. As airmail began crossingthe country successfully in the mid-1920s, railroad owners started complainingthat the government-sponsored enterprise was cutting into their business. Theyfound a friendly ear in Congressman Clyde Kelly of Pennsylvania, chairman ofthe House Post Office Committee, who largely represented railroad interests. OnFebruary 2, 1925, he sponsored H.R. 7064: the Contract Air Mail Bill, which,when enacted, became the Air Mail Act of 1925 or the Kelly Act as it becameknown. The act authorized the postmaster general to contract for domesticairmail service with commercial air carriers. It also set airmail rates and the levelof cash subsidies to be paid to companies that carried the mail. As Kellyexplained: The act permits the expansion of the air mail service without burdenupon the taxpayers. By transferring airmail operations to private companies,the government would help create the commercial aviation industry.


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Eighty percent of the stamp money received by the Post Office was to be paid tothe civilian airmail carriers. The quantity of stamps needed depended on theweight of the mail and also on how many of the three zones the mail had tocross. (The country had been divided into three air zones on July 1, 1924.)Companies saw that they would make more money if they carried smaller but

heavier pieces of mail. This led to some unethical practices, like the shipment ofphone books by friends of the contractors. Also, since they would receive thesame amount of money no matter how many miles they flew within a zone, theypreferred to fly shorter distances within a single zone and save some operatingcosts. (Davies 1998)

Harry S. New, postmaster general under President Calvin Coolidge wanted thenew contract airmail carriers to expand their routes and to buy larger airplanes tocarry passengers. He awarded contracts only to the larger companies thatbought the largest aircraft, which could accommodate passengers as well as themail. New realized that if the airlines sold more passenger tickets, which then

numbered only a few hundred each year, they could carry less mail and stillmake a profit. The companies would receive their income from payingpassengers rather than from the Post Office payment for carrying the mail. PostMaster New started by awarding eight airmail routes to seven airmail carriers,beginning in October 1925. One carrier, Ford Air Transport, won two of theroutes and was the first to fly airmail carrier under contract, starting on February15, 1926 (figure 14) (www.centennialofflight.gov/essay/Government_Role/1925-29_airmail/POL5.htm)

First Contract Mail Routes Awarded to Civilian Contract 1926Figure 14

With the passing of the 1925 Air Mail Act Congress moved rapidly with thepassing of the Air Commerce Act in May of 1926. For the first time this gave the

U.S. Government responsibility for fostering air commerce, establishing airwaysand aids to air navigation, making and enforcing safety rules. Under this act, thegovernment supplied money for air navigation facilities so that the routes wouldbecome safer to fly, day and night. Management of the route system moved tothe new Aeronautics Branch of the Department of Commerce, which wasestablished in August of 1926. This act also set the standards for levels andtypes of pilot license, mechanics certification to maintain aircraft, airmensmedicals and the government certification of U.S. Civil aircraft.
http://www.centennialofflight.gov/essay/Government_Role/1925-29_airmail/POL5.htmhttp://www.centennialofflight.gov/essay/Government_Role/1925-29_airmail/POL5.htmhttp://www.centennialofflight.gov/essay/Government_Role/1925-29_airmail/POL5.htmhttp://www.centennialofflight.gov/essay/Government_Role/1925-29_airmail/POL5.htm


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Both these pieces of government legislation would have far reaching impacts notonly to the aviation industry but also the Boeing Company and the redesignedBoeing Model 40.

The Post Office began the transition of its routes to private contractor in April of

1926 and was completed in August of 1927. They started with the routes thatfeed into the main transcontinental line but in late 1926 the Post Office asked forbids for two main portions of the transcontinental line. The two bids would besubmitted for either the San FranciscoChicago route or the ChicagoNew Yorkroute which would be transferred to the bid winners on July 1 1927. The PostOffice wanted to guard against the possibility of one operator going out ofbusiness after contract award and shutting the air mail system down for anextended period of time. The Post Office felt no one operator had the planningand logistical experience to operate the entire transcontinental air line starting outof the gate as a new operator.

Apparently William E. Boeing Chairman of the Boeing Company whose post waremployment was at an all time high of 602 employee in 1926 gave little if anyinitial thought to submitting a bid to the Post Office for either one of the longertranscontinental air mail route segments. However, as in all key moments inhistory fate was to intervene.

Eddie Hubbard, a well known local Northwest Pilot who had worked for Boeing inthe past completed along with William Boeing the worlds first internationalairmail flight into the United States from Vancouver B.C. to Seattle Washingtonon March 3 1919. (Brown 1996). Hubbard would leave Boeings employment andgo on to fly the mail and charters for fishermen going to remote lakes throughout

the Northwest. Hubbard used the first Boeing commercially design and builtaircraft as seen in figure 15. This was the Boeing B-1 (model 6) (Bowers 1989p49). Hubbard also worked for short period of time in California to takeadvantage of expanding flying opportunities. However, he remained friends withWilliam E. Boeing and Boeings then President Philip Johnson and ChiefEngineer Claire Egtvedt.


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Boeings First Civilian Aircraft Model B-1

Figure 15

In November of 1926 when the Post Office had announced plans to put its

ChicagoSan Francisco airmail route up for bids Hubbard returned fromCalifornia to meet with Boeings Johnson and Egtvedt. Hubbard had a concept inmind based on his experience flying mail and passengers between Seattle andVancouver B.C. Since Johnson was away from the office he met with ClaireEgtvedt. In the parlance of todays vernacular Hubbard presented a businesscase to Egtvedt for the successful operations on the San Francisco - Chicagoairmail route. Hubbard had estimated his return on investment (ROI) on day/nightoperations, miles flown and pounds of mail carried. During the meeting it wassuggested by Egtvedt that Boeing re-engineer the Boeing Model 40 Mailplaneusing the newly design Pratt & Whitney Wasp 420 H.P. air-cooled engine. Withthe air cooled engine it would be feasible to be successful especially with an

aircraft on a long route. After further refining their estimates they met with WilliamE. Boeing for his thoughts and input. Boeing by nature was a conservativeperson who based his success in his many business endeavors on thoroughlyanalyzing the risk involved with the opportunities presented. He did not say no toHubbard and Egtvedt when they first met but thought about the possibility overnight. The next day he came to the plant to go over the figures once again. ThePost Office would allow the winner of the bid up to $3.00 per pound for the first1,000 miles and fifteen cent for each additional 100 miles (Bauer 2006 - p37).

Based on the expected performance of the re-engineered Model 40 with the Pratt& Whitney Wasp engine William Boeing felt the numbers the team put together

were realistic and then had his team prepare a bid proposal of $2.88 for a poundof mail carried between San Francisco and Chicago. This bid proposal wassubmitted to the Post Office by the due date of January 15, 1927.

The reason Eddie Hubbard, William Boeing and the Boeing engineering staff feltconfident they could be successful with the bid proposal submitted was theirfamiliarity with the relatively new power plant designed and developed by the



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recently formed company called Pratt & Whitney Aircraft Company of EastHartford, Connecticut.

The Pratt & Whitney Aircraft Company

Frederick Rentschler had resigned as president of the Wright AeronauticalCorporation on September 21, 1924. When the Wright Company was looking intothe possibility of the radial engine they examined a possible merger with theLawrance Engine Company who had been one of the pioneers working on the aircooled engine concept since 1921. Rentschler after studying the LawranceCompany operations and engine designs advised his board against such anacquisition. In his own words a completely confused manufacturing operation.(Pratt & Whitney 1950 p28). From that point on Rentschler had difficulty with theWright Aeronautical Board, made up mostly of bankers owning little stock in theWright Company who only wanted immediate return on investment (ROI) ratherthan longer research and development efforts for the possibility of greater ROI.

When he departed Wright Aeronautical, Rentschler sought the advice of anotherindustry icon, Chance Vought, Rentschler told Vought of his plan to create anorganization where management and engineering drove the organization.Rentschler laid out a plan of what such an organization would look like in order todesign and develop an air-cooled radial engine capable of 400 plus horse powerwith as many modern features as possible. (Pratt & Whitney 1950 p32). Afterlistening to Rentschlers proposal Vought urged him on to look for backers for hisconcept and plan. So six month after resigning from Wright AeronauticalRentschler went to see the Pratt & Whitney division of the Niles-Bement-Pond amachine tool company of Hartford Connecticut. He asked them for $425,000 tobuild a prototype engine. With his past experience and reputation in the aircraftindustry, especially with engines Bement-Pond accepted the proposition.

On July 23, 1925 Pratt & Whitney Aircraft was incorporated with Rentschlerpresident, George Mead vice president and Andy Willgoos chief engineer. Meadand Willgoos had both left Wright Aeronautical to joined Rentshler at Pratt &Whitney. They and those they hired worked around the clock on the new designand manufacturing processes of their prototype air cooled radial engine. Theironly numerical goals was to develop 400 H.P. within a weight of 650lbs.December 29, 1925 they started the engine for the fist time and within in a fewdays it was delivering 425 H.P. within the 650lbs limit. The Pratt & Whitney Waspengine was born. (figure16)


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But Boeing would have a supply of Wasp engines on hand for the 32 F2B theywere going to build as soon as funding was approved. (Bower PNAHF JournalVol. 8).

The other main bidders for the Chicago San Francisco route were Western Air

Express and National Air Transport. Both were experienced well financed airlineoperators already flying shorter contract mail routes. Western Air Express hadan excellent reputation of flying the Liberty powered Douglas M-2 (figure 8)mailplanes across the mountainous country between Los Angels and Salt LakeCity while National Air Transport had six Curtiss Carrier Pigeon, (figure 7) alsoLiberty powered built specially for the use on Chicago New York portion of theroute. When the bids were open and evaluated by the Post Office in the latterhalf of January 1927 the Boeing bid was the lowest coming in at $2.88 per poundof mail for the whole journey. This beat by a substantial margin the next closestbidder, Western Air Express, that was $4.25 (Davies 1972 p59). The advantageof using the relatively new technology Pratt & Whitney air-cooled engine allowed

Boeing to bid at the unprecedented low bid. The engine weighing 200 poundsless than the older Liberty translated into passenger capability as well as moremail that could be carried. As William E. Boeing told anyone who would listen. Iwould rather fly 200 more pounds mail than water. (Pratt & Whitney 1950) Afterwinning the contract on January 29, 1927 the Post Office required an insuranceperformance bond. The Post Master was reacting to other competitor companiestelling him the mail could not be carried for such a low cost as Boeing submitted.William Boeing personally wrote a $500,000 bond so the Boeing Organizationcould continue with its plan to operate an airline. (AAHS Journal Vol. 49 - P114)On February 17, 1927 Boeing Air Transportation was incorporated.

Bringing the Boeing Model 40A to Production

Key Events and Activities

Now the Boeing team had five main challenges; (1) to complete the redesign oforiginal Model 40 prototype, (2) acquire enough Pratt & Whitney Wasp engine toproduce 25 Model 40As with spares, (3) hire the personnel to fly and maintainthe new aircraft along the route (4) be ready to begin operations along the entireroute in six-months starting July 1, 1927. (5) comply with the new airworthystandard set forth in the recently passed legislation called the Air Commerce Actof 1926. This legislation was signed into law by President Calvin Coolidge onMay 26, 1926. (van der Linden 2002) This act effectively established the firstregulations in the United States for the certification of airmen, airways andaircraft. The Air Commerce Act created an Aeronautics Branch charged with thepromotion and regulations marking the beginning of civil aviation oversight in theUnited States. (Emme, Hallion, Two Hundred Years of Flight in America, 1976p158) This would also be a learning curve since no manufacture had gonethrough the Aircraft Type Certification (A.T.C.) process which now had to be


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followed and complied with under the Act. The Boeing Model 40A would only bethe second aircraft to do so when it received A.T.C. #2 in July 1927.

Eddie Hubbard went off to Salt Lake City, the city where three of the five exitingair mail routes came together. It was an excellent location to hire personnel for

the new Boeing airline operation. The first 21 pilots came from the Post Office AirMail Service. All of them had many hours of experience flying the mail for thePost Office. (AAHS Journal Vol. 49 - P114) This would be a real plus for manyreasons especially when it came to attracting passengers by highlighting theexperience of the lines pilots.

In the mean time William Boeing himself was instrumental in securing the neededand critical Pratt & Whitney Wasp engines for the Model 40As. Fred Rentschlerand William Boeing had become friends (Figure 18) when the Wasp engine wasmated to the Navy F2B-1 Fighter. The Boeing Company was contracted to build32 for the Navy. Unfortunately, all the Wasp engines had been committed to the

F2B contract therefore making it impossible to obtain the new enginecommercially for at least a year. However, William Boeing through his friendshipwith Rentschler was able to arrange with the Navy to release Wasp engines tothe Boeing Model 40A project with an assurance from Rentschler thatreplacements Wasp would be available when needed for the Navy F2B-1contract. (Bower -1966 p116).

Through this collaboration with Pratt & Whitneys Rentschler, William Boeing, theBoeing engineering staff and production personnel would have the needednumbers of Wasp engines required for the Model 40A. (figure 18)

Boeing and Rentschler inspect WaspFigure 18

Here is an interesting speculation, What if Boeing and Rentschler hadnt had thefriendship they had, how would that have affected the course of Boeing History?However, what did occur because of Rentschlers arranging an agreement with



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the Navy Bureau of Aeronautics was that the Boeing Airplane Company wouldbegin receiving 5 Wasp engines per month beginning in February 1927. Inaddition, they would receive 3 extras spare engines for a total of 28 when flightoperations began on July 1, 1927.

The Boeing engineering team under Egtvedt had been working on the redesignof the Model 40A with the possibility of the Pratt & Whitney Wasp engine evenbefore initial discussion with Eddie Hubbard in November of 1926.

At first glance when one compares the specification and performance numbersbetween the original Model 40 and the new Model 40A using the Pratt & WhitneyWasp there appears to be little apparent difference (Figure 19 a & b).

Model 40 Redesign with P&W Engine

Figure 19



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Aircraft Boeing Model 40 Boeing Model 40A

First Flight 7-July 1925 6-June-1927

# Produced Prototype 25

Pilot & Pax Pilot OnlyPilot / 2 OptionalPax

Powerplant Liberty 400 h.p. P&W 420 h.p.Wing Span 44'2" 44'2"

Length 33'2" 33'2"

Height 12'3" 12'3"

Empty Weight 3,425 lbs 3,531 lbs

Gross Weight 5,495 lbs 6,000 lbs.

Speed 135 m.p.h 128 m.p.h.

Range 700 miles 650 miles

ceiling 15,800' 14,500'

Boeing Model 40 and 40A ComparisonFigure 19a

Model 40s Summary Performance Chart

Figure 19b

However, due to the 200 lbs. reduced weight of the Pratt & Whitney air-cooledengine verses the older Liberty 12 engine which translated into increased

payload not only in mail but allowed for two passenger to fly the route to generateadditional income above the mail contract compensation. This plus the addedbenefit of the Wasp engines increase in reliability allowed Boeing to submit theirrelatively low bid when compared to the others in the competition.

From a dimension point of view the two Model 40s were identical. The wingconstruction on both used spruce and ribs with fabric covering a six foot seveninch Clark Y airfoil (figure 20). This airfoil would suit the operational

0

1000

2000

3000

4000

5000

6000

7000

Boeing Model 40 Boeing Model 40A Boeing Model 40B-2 Boeing Model 40B-4

Boeing Model 40 113 700 5495 3425 2070 400

Boeing Model 40A 105 650 6000 3531 2469 420

Boeing Model 40B-2 105 650 6000 3531 2469 525

Boeing Model 40B-4 125 535 6075 3722 2353 525

Speed

mph

Range

miles

Gross

Weight

lbs

Empty

Weight

lbs

Useful

Load lbs

Engine

HP


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requirements for the high altitude because of with its good high lift flightchacteristics. The inter-plane struts on the Model 40A eliminated the woodendiagonal braces between the main forward and aft members that were on theModel 40. They were replaced with heavy flying wire bracing on the 40A.

Figure 20

The Model 40A fuselage structure was also completely different than the Model40. As seen in figure 21 the fuselage structure was welded tubular steel ratherthan the wood veneer fuselage of the prototype Model 40.

Boeing Model 40A Steel Truss FuselageFigure 21

The steel truss airframe was built up with non-load bearing wood stringers that

provided the rounded and streamline shape to the fuselage before being coveredwith cotton fabric and sections of dural aluminum sheet metal.

Boeing Model 40 Clark Y Airfoil 6 7



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Boeing Model 40A Fuselage Configuration

Figure 22

Figure 22 shows the airframe configuration for the pilot, two passengers, mailand baggage bins. This arrangement provided the aircraft a great deal offlexibility for load and management of the center of gravity for weight and balancepurposes. On the Model 40A there is a passenger door on each side of thefuselage. The passenger cabin area was metal lined throughout with the seatcovered in leather. (figure 23) An airspeed indicator along with an altimeter wasalso located in the cabin. The non-shattering glass window could be open in flightand was large enough to provide excellent view of the scenery. A dome lightcould provide limited light at night. A 100 gallon fuel tank was provided justbehind the aft mail bin. This configuration would change in subsequent Model

40s to using three different fuel tanks. The Model 40B would have one fortygallon tank located in the upper right center section with other two located on theright and left side lower wing root area.

Model 40A Two Passenger CompartmentFigure 23


Boeing Historical ArchivesBoeing Historical Archives

Front baggage bin 25 cu.ft.

Passenger compartment

Pilot Cockpit

420 hp Wasp Engine

Aft mail bin 37 cu.ft.



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The Model 40B-4 and Model 40C would have the same configuration. However,the upper wing tank had a capacity of 60 gallons. Figure 24 shows schematicallyarrangement which was basically the same on all Model 40 versions after theModel 40A.

New Model 40 Fuel System - After the Model 40AFigure 24



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Model 40A Pilots Cockpit

Figure 25

The cockpit was fairly typical for its day. The mixture and throttle controls wereon the left side with the standard flight instrument that included altimeter and turnand bank. Cockpit lights were also standard to illuminate the instruments duringnight operations. (figure 25). The landing gear used the new air-oleo strut ofBoeing design.

The overall redesign of the Model 40A was strong, functional and producible. Allthese attributes would be important for the operational success of the aircraftwhile flying the Contract Air Mail (CAM) Route #18 from San Francisco toChicago.

The Boeing Seattle factory had to build and certify twenty-five planes and thentest fly them in less than five months. To add to this challenge when the aircraftwere completed (figure 26) they had to be trucked 15 miles away from theBoeing factory to Sand Point located north and east of factory on LakeWashington because Boeing did not have a long enough runway near thefactory. At Sand Point a pasture was cleared among the pines to serve as theneeded runway. This location also served as, King County Airport until 1928when Boeing Field formally opened. (figure 27)

Rudder BarMixture &Throttle

Mounted NightLights

Fuel TankSelector



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Completed Boeing Model 40A

Figure 26

Sand Point Testing LocationFigure 27

From contract award in February 1927 to being operationally ready on July 1,1927 it was an all out effort for the Boeing team. When Pratt & Whitney sentWilbur Thomas one of its early service representatives to support Boeing he wasshocked and concerned how much there was left to do. Arriving on June 1 st1927Thomas found only one aircraft completed. (Pratt & Whitney 1950) From thatpoint on one plane per day seemed to be completed. Then immediately after ashort test flight the aircraft was flown off points along the route. By midnight June

30th

all 25 Model 40As were in place along CAM #18 to begin operations the nextday as per the contract. Ever 24 hours the new model 40As with their Waspengines would cover 4000 miles on the round trips between San Francisco andChicago.




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The Boeing Model 40 - Transcontinental Line Operations

Boeing Air Transport began air mail service as scheduled on July 1, 1927 fromSan Franciscos Crissy Field. The day before Mrs. Bertha Boeing, WilliamBoeings wife, sitting on the right side of the platform (figure 28) between two

gentlemen christened the inaugural Model 40A aircraft City of San Francisco.

Inauguration Day Boeing Air Transport - Crissy FieldFigure 28

The next day at the other end of the line in Chicago Boeing Air Transport (BAT)boarded their first passenger on a Model 40A. A reporter from the ChicagoHerald Examiner Jane Eads took off at 9:30 PM with former Post Office Pilot IraBiffle now working for BAT and they headed west bound. As the trip progressed

west Eads gave positive reports and statements to the media, such as, I couldfly forever. (Bauer 2006 p 39) Eads completed her trip after 23 hours of flyingtime and BAT was officially in the business of both flying the mail andpassengers.

Due to terrain, weather conditions and a lack of navigational land marks it wouldhave been hard to find a more challenging route to begin operations. As figure 29illustrates the Midwestern section of the route between Iowa City and Omahalooks like it could be flown with deceptive ease.



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Figure 29

However, from North Platte a long steady climb to Cheyenne was begun flyingwestbound as the route penetrated the Rockies Mountains to Rock Springs. Aftertopping the saw-toothed Wasatch Mountain Range at 7000 feet it was a descent

to the hot salt flats of Salt Lake City. From Salt Lake to San Francisco there wasmore mountain high country between Elko and Reno before another majorascent over the Sierra Nevadas finally descending down into the SacramentoValley and landing at the Oakland Municipal Airport. The eastbound was just asrigorous with a maximum climb to Reno and not descending until afterCheyenne.

The schedule route time from Chicago was approximately 20 flying hours plus.Passengers who would follow Jane Eads would pay $200 one way to ride inrather confined by enclosed passenger compartment in front of the pilot (figure24). Choosing this method of transportation BAT passengers found they had

taken 43 hours off the enroute time compared to taking the train between the twocities of Chicago and San Francisco. (Davis 1982).

With mail and passenger operations now becoming a daily event the Pratt andWhitney Wasps engines were proving themselves in the field. After some minoroverheating problem during the first two weeks of operations they becameincredibly reliable passing the then standard 200 hours of operation beforeoverhaul. The reliability of the engine and the paying passenger carried in the


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Model 40A allowed Boeing Air Transport to astound its critics and make a profitduring the first year of operations. (Davis 1982, p60).The inaugural year saw BAT fly a million and half miles over the route. At the endof two years they had flown 5,500,000 miles while delivering 1300 tons of mailand 6000 passengers. The 24 months of initial flight operations was also

accomplished with a good safety record for the time. Only three fatalities wererecorded for an average of one for every 1,750,000 miles flown. These types ofmetrics helped to sell the idea of air travel not just to the adventurer but to thegeneral public and business professionals as well. This positive response washelped in no small measure by the effects of Charles A. Lindberghs successfulflight from New York to Paris on 27 May 1927. This not only sparked peoplesimagination to the possibility of air transportation but it facilitated financiers to theinvestment potential of the aviation industry. It seemed like almost over nighteveryone wanted to become involved with the aviation industry. Pilot startsincreased dramatically with more Research and Development (R&D) moneybecoming available from government, foundations and industry for the

development of aircraft and aircraft support functions, including the developmentof those items listed in figure 30. These examples of R&D projects had begun ata slow pace in mid 1920s became a rapid evolution during the decade of the1930s. (Whitford, 2007)

1924 -1929 AIRCRAFT TECHNICAL DEVELOPMENTS

RADIAL ENGINES

DRAG REDUCTION

AIRCRAFT STRUCTURAL IMPROVEMENTS

WING FLAPS

RETRACTABLE LANDING GEAR

INSTRUMENTATION

AIRCRAFT SYSTEM

Figure 30

Aviation and technology historian John Anderson would identify this era in

chapter 6 of his book The Airplane, A History of the Its Technology as The Eraof the Mature Propeller-Driven Airplane. The Boeing Model 40A which from anew aircraft technology point of view was at the back end of an old aircraft designconcepts was however, with the Pratt & Whitney Wasp radial air cooled engine,at the front end of the rapidly developing industry change. The Model 40A madeit possible for the Boeing Company to be in the right place to participate in thisgrowth. Shortly after the Model 40A made its introduction with BAT another Pratt& Whitney engine with more horsepower was being developed for the higher


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altitude landing fields along the route, especially west of Cheyenne. This enginewas called the Hornet. The design began in January of 1926, making its firstflight in June of the same year. The new air cooled radial engine offered 525 hp,an increase of 105 horse power over the Wasp engine of 420hp.

Although Boeing Air Transport had a separate identity from the parent BoeingAirplane Company BAT was managed from Seattle. With the positive results theywere achieving on their section of the transcontinental line (CAM #18) Boeingmanagement made two major decisions in 1928. One they would convert most oftheir Model 40 As to the new Pratt & Whitney 525 hp Hornet engine. With thischange to the Model 40A they would become Model 40Bs. On a rotationalschedule they were flown back to the factory in Seattle for the engine changethen back to flying the line. However, since this engine change altered the Model40As gross weight to 6075lbs along with other flight performance numbers it hadto be re-certified; on February 1928 ACT #27 was awarded making those Model40As Model 40Bs. The other major decision was made on January 1, 1928 when

Boeing Air Transport acquired control of Pacific Air Transport (PAT). PAT was acontract air mail carrier on CAM #8 which paralleled the west coast form Seattleto San Francisco. The acquisition provided a direct link from the Boeing Seattlefactory to the western end of the transcontinental route in San Francisco, as wellas, a market for additional Boeing transports. In May of 1928 Pacific Air transportbegan operating six Boeing 40Bs. (Davies 1982 p70). This merger alsonecessitated a name change to The Boeing System for the combined lines.

Logo Change for combined Boeing System LineFigure 31



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Figure 31 shows the revision made to the logo to accommodate themerger of the two lines. On the former PAT route the words AIRTRANSPORT, INC were removed from the circle and replaced by thesingle SYSTEM, while the words PACIFIC AIR TRANSPORT werepainted on a straight line flanking the logo. The original logo was retained

for the Boeing Air Transportation routes. (Bower 1966 P117) Boeingmanagement in Seattle continued to oversee and provide strategicdecision making for both lines in the SYSTEM. As reported in United

Aircraft & Transport Corporations first annual report to stockholders in1929 the two transport companies completed flying 8 million miles inDecember of that year and at the time were considered to be the mostefficiently operated mail-passenger lines in the United States. (1929UATC Annual report p 41)

The re-engineered Boeing Model 40 was making it possible for the BoeingCompany to fulfill its original charter to "To engage in the business of

aerial navigation by any means whatsoever, heretofore or hereafterinvented or developed, including also to act as a common carrier ofpassengers and freight by aerial navigation..." (Boeing Historical Archives-

Articles of incorporation Pacific Aero Products 1916) From this point onexpansion and opportunity would continue at a rapid pace for the Boeing

Airplane Company.

United Aircraft and Transportation Corporation

Some air mail contract operators didnt believe the passenger businesswould ever be profitable. They felt the money spent for marketing to apotential passenger was money thrown away. When passenger did showup for a flight the mail bags were often treated better. What the operatorswanted was a faster aircraft that could carry heavier payloads than theexisting aircraft on flying the line.

William E. Boeing and Fred Rentschler had another concept in mind. Whynot increase passenger revenues on top of the air mail contract revenues.Bigger and faster aircraft were needed but carrying more passengers inbetter comfort seemed to have a greater potential. Rentschler who likeworking with Boeing on the Model 40s production and the results theywere achieved suggested that they form a partnership between their twoorganizations which could capitalize on their mutual strengths in thecommercial aviation market. From these initial discussions severalmergers were consummated in late 1928 into 1929 between The BoeingCompany, Pratt & Whitney and other aviation companies. These mergeragreements lead to the formation of United Aircraft and TransportationCorporation on February 1, 1929. It was a holding Company whoseoriginal members included Pratt & Whitney Engines; Boeing AirplaneCompany; Chance Vought; and Hamilton Aircraft Propeller. A short time


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later Standard Propeller, and the Stearman Aircraft Corporation wereadded to the engineering and manufacturing companies. On the airtransport side of the organization, National Air Transport which now flewroutes from Dallas Texas to New York via Chicago along with Varney AirLines whose route ran from Reno, Nevada to Pasco Washington via Boise

Idaho were added to Boeing Air Transport and Pacific Air Transport Line.As a result of the increase in air transportation routes and activity a newmanagement company was formed to handle the growth and the BoeingSystem became United Air Lines. (Pratt & Whitney p73) The United

Aircraft and Transport Corporation Model 40s were now flying thetranscontinental line. (Figure 32)

Boeing Model 40A Air Transport with after the fact Photo touch

up with United Airline Marking. No actual Model 40A had this logoFigure 32

With $146,000,000 of total capital between the Equipment and TransportCompanies this formed a formable aviation conglomerate as can be seenfrom the scope of the organization chart for UATC in figure 33 below.

By 1929 BAT was operating 46 aircraft on the line, many of which wereModel 40 B-2s and 40B-4s (four passengers Model 40bs).

.



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Figure 33

The Organizations listed under United Aircraft & Transport Corporation intheir 1929 Annual Report to Stockholders were:

Equipment Companieso The Boeing Airplane Companyo `Boeing Aircraft of Canada, Ltd.o The Hamilton Standard Propeller Corporationo Northrop Aircraft Corporation, Ltd.o The Pratt & Whitney Aircraft Companyo Canadian Pratt & Whitney Aircraft Co., Ltd.o Sikorsky Aviation Corporationo The Stearman Aircraft Companyo Chance Vought Corporation

Transport Companieso Boeing Air Transport, Inc.- Pacific Air Transporto Stout Air Lines

Other Operationso Boeing School of Aeronauticso United Aircraft Exports, Inc.o United Airport Company of California, Ltd.o United Airports of Connecticut, Incorporated


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The headquarters for UATC organization was located in East HartfordConnecticut with Fred Rentschler as President and William Boeing asChairman of the Board. The timing for the formation of UATC could nothave had happened at better time because by the late 1920s othergroups were forming large aviation corporations as well North American

Aviation, which acquired the Curtiss-Wright Corporation. The automanufacture, General Motors, got into the mix as well by acquiringWestern Air Express. Aviation was now big business and the financierswanted to get into the act by bringing competition into the industry withadditional mergers.

The UATC companies were now in a position to deal with the increasedcompetition growing in the commercial aircraft market place from theseother mergers. Additionally, many companies that were part of UATC wereable to survive the trouble ahead when the stock market and worldeconomy suffered a depression starting in November 1929. However,

before the reality of that became evident the Boeing Model 40 whichinitially brought Boeing and Pratt & Whitney together was constantly beingmodified and improved during the merger and acquisition process thatformed UATC.

The strength of UATC was the rich talent of the combined companiesengineering and production staffs. They formed a technical advisorycommittee for the purpose of interchanging of ideas, unity of efforts andmaking available the benefits of research to all.

This would improve and accelerate aircraft design while enhancing safetyimprovements for flight operations.

One example of this type collaborative effort in R&D was led by BoeingsThorp Hiscock. (figure 34) He suggested that radioing updated weatherinformation to pilots en route could eliminate some of the uncertainty, andthen offered to solve the problem. With approval from the Boeing AirplaneCompany, he began experimenting with low-frequency radio transmittersand receivers. Hiscock had radio receivers and transmitters installed insome Model 40s. He soon achieved what others before him had not:ground-to-air radio communication. This major break through step wouldhelp to tremendously improve flight safety by having pilots while in the airreceive the most current weather and flight information


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Boeings Thorp Hiscock

Figure 34

How many were Built and What Model 40 is it

The following is a summary of the variations of the Model 40 built. As seen

below in figure 35 the total number of Model 40s built was 82.

Model Year Buil t ATC Number Number Buil t

40 1925 Not Required 1

40A 1927 2 25

40B-4 1929-1931 183 39

40C 1928-1929 54 10

40X 1928 54 1

40Y 1928 183 1

Total U.S. Boeing Built 77

Non U.S. BoeingCanada

40H-4 1929-1931 Non - U.S. 5

Total Boeing U.S. & Canada Model 40s 82

* Last Canadian Aircraft Msn CB-9 not Completed

Model 40 Production NumbersFigure 35


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There has seems to be a bit of confusion over the total number of Model40s built, with both 81 and 82 being documented.

Boeing has Manufacture Serial Number (Msn) Data Cards for each aircraftconstructed going back to the original 1916 Boeing & Westervelt B&W bi-

plane. Reviewing these Msn data cards show the total number of U.S.Boeing Model 40s built to be 77. However there were 5 Canadian builtModel 40s built by Boeing Aircraft of Canada Ltd. In Vancouver, B.C.

Boeing also issues a Model Specification and History data sheet for eachBoeing Commercial Aircraft. These sheets provide basic specificationsand performance numbers for the aircraft model, as well as, numbers ofthat model built. In many cases the Boeing Model Specification andHistory data sheets list the Msn(s) for the Model as part of the referenceswith in the context of Model Specification and History sheet information.

The Model 40B-4 Specification and History sheet has recorded 38 builtwith the Msn listed on page 3 of the sheet. However, Boeing ManufacturesSerial Numbers issued for the Model 40B-4 (Msn) as recorded in their MsnData Cards show 39 aircraft. The additional 40B-4 is Msn 1164 whichBoeing identifies as a 40B-4A sold to Pratt & Whitney with a Pratt &Whitney 650 H.P. engine and a three bladed propeller.

Aviation Historian Walt Bohl in his excellent summary article on the Model40s in the American Aviation Historical Society Journal (Summer 2004volume 49 Number 2) list all the Model 40B-4 built by Msn.

Four Passenger Model 40B-4Figure 36



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Bohls lists MSN 1164 for the Model 40B-4 not found on the Boeing ModelSpecification and History sheet. Bohls list also matches the Boeing MSNdata cards for the Model 40B-4 found on file in the Boeing Archives.

The Msn listed in Bohls article and the Boeing Msn Data cards came to39 Model 40B-4 in both counts. However, Bohls summary of the numberof Model 40B-4 built at the end of his article shows 38 Model 40B-4s built

Apparently, Bohl didnt include MSN 1164 as a model 40B-4 in his finalcount or it was a miscount being recorded as 38 instead of 39 found in hisarticle showing the list by Msn numbers.

This author has verified Bohls list of 39 with Msn Data Cards on file withthe Boeing Historical Archives. The Model 40B-4 Msn that was listed inBohls article and in the Boeing Msn Data Cards match including Msn1164 delivered to Pratt & Whitney on October 10, 1929.

The Model designation for the Pratt & Whitney aircraft was Model 40B-4A.The information seems to confirm that 39 Model 40B-4s were built not 38as previously reported in a variety of sources. This would bring thenumber of U.S. Boeing built Model 40s to 77 and shown in figure 36.

However, the confusion doesnt stop there. Another area of confusion wasthe number of Canadian Build Model 40s. During the merger activitybetween1928-1929, Boeing established a factory in Vancouver, B.C.called Boeing Aircraft of Canada Ltd. They built 5 Model 40s confirmed bytheir Msn system. Their version of the Model 40B-4 was called the Model40H-4. This was an aircraft basically the same as the Model 40B-4. TheH in the Model designation was used to honor the Boeing CanadianCompany President Henry Hoffar. From late 1929 to early 1931 theyissued 5 Canadian Msns for their Model 40s. However, only four werecompleted. Msn Canada-Boeing (CB-9) was not completed and put instorage then sold in 1936 to United Air Transport Canada. After which itwas then given to Calgary Institute of Technology and Art. (AAHS JournalSummer 2004 volume 49 Number 2). That is why some historical aviationreferences refer to 81 Model 40 being built. The official recorded Msnsfrom Boeing U.S. and Canada-Boeing records show the numbers to be 82airframes built with 81 Model 40s that actual flew.

Figure 35 also shows seven Model 40 variation designations with fourU.S. Aircraft Type Certifications assigned to six of the seven designations.The last certification was issued by the Canadian Government for their 5Model 40s built by the Boeing Factory in Vancouver, B.C. However, in theliterature covering the Model 40s reference is made to two other Model 40variations.


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The following will be an attempt to explain these designations and therational behind the designation.

The straight Model 40 built for the Post Office in 1925 did not receive anATC number due to the fact it was designed and built before the

regulations came into effect in 1926 under the Air Commerce Act.

The 25 Model 40As were built in 1927 for the Transcontinental Line andequipped with the Pratt & Whitney Wasp engines. They were issued ATCnumber 2 under the 1926 under the Air Commerce Act in July of 1927.

The Model 40Bs as mentioned earlier in the article were Model 40Asmodified with the higher 525 horsepower Pratt & Whitney Hornet engine.Due to their weight and performance numbers changes these aircraft hadto be re-certified and were issued ATC number 27. However, the Model40B was never a production Model 40 for Boeing since they were modified

Model 40As.

The Boeing Model 40Cs were built after the Model 40As were convertedto 40Bs. The Model 40C of which ten were built were identical to theWasp-powered Model 40A except the rear mail bin compartment wasconverted to carry two additional passengers. They had two doors on theleft hand side of the fuselage. The Model 40C received ATC number 54.They were delivered to airline customer, Pacific Air Transport, in August of1928. They cost at the time $23,500. (Bower PNAHF Journal Vol. #8).One Model 40C went to National Park Airways. Later seven of the 10Model 40Cs were converted to Model 40B-4s by the converting the Pratt &Whitney Hornet engine installed on their airframe.

The Model 40B-4, which 39 were built between 1929 and 1931 under ATCnumber 183 was a production 4 passenger aircraft with the Pratt &Whitney Hornet engine factory installed at the time of construction. Whenthese aircraft became operational with Pacific Air Transport, Western AirExpress, Varney Airlines and others it caused a retroactive Modeldesignation change to the existing Model 40Bs flying with installed Hornetengine certified by ATC number 27. They remained under that certification

ATC number but became Model 40B-2s to differentiate from the new fourpassenger Model 40B-4s under ATC number 183.

As discussed above there were the 5 Boeing-Canadian Model 40H-4swhich were basically the same as the Model 40B-4s.

Additional there was also two one of a kind Model 40 variation with theirown designation. These were the Model 40X and Model 40Y.


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The Model 40X was a 4 passenger aircraft sold to Associated OilCompany in 1928 with Pratt & Whitney Wasp engine in 1928. It was builtunder ATC Number 53 used for the Model 40Cs. The Model 40Y also soldin 1928 was the Pratt & Whitney Hornet powered 4 passenger aircraft builtunder ATC # 183 and sold to Standard Oil of California.

Where Are They Now

Currently there are there two original Boeing Model 40s in existence. Oneis located in the Chicago Museum of Science and Industry where it hangson display.The Chicago Museum of Science and Industrys particular Model 40 is aModel 40B-2 Msn 888 which was displayed at the Wings of a Centurypageant at the Century of Progress Exposition in Chicago in 1933. Afterthe world fair exposition this aircraft with 6000 plus hours on the airframe

was donated to the Rosenwald Museum (now called the Chicago Museumof Science and Industry) in November of 1933. Following a period of timein storage it was hung from the ceiling in 1939 where it remains and canbe seen today.

The other is located in the Henry Ford Museum in Dearborn Michigan.This is also a Model 40B-2 Msn 896 with over 6000 hours on the airframe.The aircraft had an interesting history that included heavy repairs due tolanding accidents, installation of 100 lbs radio equipment with mast andconverted to an airline instrument trainer for National Air Transport. (AAHSJournal Vol 49 Number 2 summer 2004 p117)

However, there are three other Model 40s, two replicas and onereproduction. The two Model 40s replicas were by Century Aviation ofEast Wenatchee, WA. One is a Model 40B fuselage sitting on its landinggear in the Museum of Flight, Seattle Washington. This can be currentlyseen on display in the Museums Boeing Red Barn exhibit area. (figure37)


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Model 40B replica fuselage - The Museum of Flight

Figure 37

The other is an exact replica of a Model 40B-2 delivered in October 2007

also to the Museum of Flight. This Model 40B-2 is part of The Museum ofFlights Air Mail Exhibit in the Museums Great Gallery. The Model 40Bsfor the Museum of Flight have been supported and inspired by Mr. WilliamE Boeing Jr. son of The Boeing Company Founder William E. Boeing. Theaviation community is very fortunate to be able to see up close the sizeand features of these historic aircraft from the ground level.Historical aircraft on display in this manner help to educate and bring alivethe pioneering efforts of those who established the civil aircraft industry inthe United States.

Also, in Washington State Pemberton & Sons Aviation has another Model

40 in restoration that is nearing completion. This one will be a flyingreproduction of an original Model 40C. With the original data plate and 50original components integrated into the reproduction this will be only flyingexample of a Model 40 in the world. This aircraft is also scheduled tomake its debut within the next six-months. Pemberton & Sons intend tohave this aircraft on display at selected air shows. They also plan to fly theCAM # 8 route between Seattle and Los Angles making stops along theroute at or near the original airfields. That truly would be a wonderful mustsee event to witness this aircraft in the air once again.


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Pemberton & Sons Photo

Pemberton & Sons Aviation Reproduction Model 40CFigure 38

Summary and Conclusion

Boeing constructed various marks of the Model 40 between 1926 and1931. From an aircraft engineering, design and production point of view itwas a basic aircraft even for its time. They receive little if any mention inaviation history books on their contribution to the industry. According toHeppenheimers authoritative history on the commercial aviation industryhe stated. In their technical design, airplanes in the 1920s were generallyfailing to advance One could see this in the Boeing 40 of 1927, built adecade after the war. It had an air cooled engine, but in other respects itslayout remained thoroughly conventional. It showed a fuselage frameworkbuilt of welded steel tubes, a construction technique that dated to 1916.Other features included the usual: open cockpit, biplane wings with spruceribs fabric covering This stodginess in design contrasted sharply withthe great freedom available to designers. (Heppenheimer 1995, p.15).

Yet the Boeing Model 40 was a historically significant aircraft if not from anengineering point of view but from the perspective they were the rightaircraft, at the right time and place to play a significant role in the overallgrowth of aviation manufacturing and the airline industry. This point hasbeen repeatedly missed in aviation histories of this era. The Model 40swere an excellent aircraft to introduce the concept of the air cooled radialengine to the commercial aircraft market. Boeing Air Transport was able tomake a profit in the first year of operation flying the line with the Model40A.


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It is purely left to speculation as to what would have happen to the BoeingCompany if they had not produced the Model 40A and win the SanFrancisco-Chicago portion of the Transcontinental Line. But without theModel 40s the Boeing Airplane Company at the time would not have been

in a leadership role with Pratt & Whitney in forming the United Aircraft andTransport Corporation. As Museum of Flight exhibit Technician, historianand docent educator, John Little put it succinctly The Boeing Model 40swere the most important aircraft Boeing ever designed or built, theyallowed Boeing to survive and put them in the drivers seat when it came tothe agreements of the mergers that formed UATC. As a telling tribute asto what William E. Boeing thought of the Model 40 venture his son Mr.William E. Boeing Jr. told the author, The Boeing Model 40 was the onlypicture of a Boeing airplane we had hanging anywhere in our house.

Apparently even at the time Mr. William E. Boeing realized the historicalsignificant of the Model 40 to the Boeing Airplane Company. Perhaps to

him the Model 40 represented the reaching of the goal he had set toachieve as stated in the articles of incorporation when he first set up thecompany, "To engage in the business of aerial navigation by any meanswhatsoever, heretofore or hereafter invented or developed, including alsoto act as a common carrier of passengers and freight by aerialnavigation..." (Boeing Historical Archives- Articles of incorporation Pacific

Aero Products 1916)

Century Aviation Photo Fig. 39

Century Aviation Built Boeing Model 40B for The Museum Of FlightFirst Public Roll Out Wenatchee, WA. October 6, 2007


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Pictures of the constructions of The Museum of Flight Model 40B replica

2005-2007

A collection of photographys of the Model 40B Construction

Figure 40


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Bibliography and References

Conversations

William Boeing Jr., Museum of Flight Trustee

Addison Pemberton, Pemberton and Sons Aviation, Model 40Reproduction - Will be only one left flying.

Mark Smith, East Wenatchee Century Aviation, Model 40 Replica Museum of Flight Model 40B replica and fuselage

Selected Websites

Air Mail Pioneers: www.airmailpioneers.org/

American Institute of Aeronautics and Astronautics: http://www.aiaa.org/

National Postal Museum; www.postalmuseum.si.edu

Pratt & Whitney: www.pratt-whitney.com

Smithsonian National Air and Space Museum: http://www.nasm.si.edu/

The Boeing Company: www.boeing.com

Periodicals

American Aviation Historical Society Journal

Volume 49, number 2 summer 2004

Archives

The Boeing Company - Seattle, Washington

The Museum of Flight Seattle, Washington
http://www.airmailpioneers.org/http://www.aiaa.org/http://www.postalmuseum.si.edu/http://www.pratt-whitney.com/http://www.nasm.si.edu/http://www.boeing.com/http://www.boeing.com/http://www.nasm.si.edu/http://www.pratt-whitney.com/http://www.postalmuseum.si.edu/http://www.aiaa.org/http://www.airmailpioneers.org/


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Books

Authors Name Title Publisher Year

Bowers, Peter Boeing Aircraft since 1916 Naval Institute Press 1989

Bowers, Peter Curtiss Aircraft 1907-1947 Putnam 1979

Brown, Jim Hubbard The Forgotten Boeing Aviator Peanut ButterPublishing

1996

Dvaies, R.E.G. Airlines of The United States Since 1914 Smithsonian InstitutionPress

1982

Revised EditionEmme, Eugene MEd.

Two Hundred Years of Flight In America AmericanAstronautically Society

1977

Francillon, Rene' J. McDonnell Douglas Aircraft since 1920:Volume I

Naval Institute Press 1979

Hallion, Richard P. Legacy of Flight: The GuggenheimContributions to

University ofWashington Press

1977

American Aviation

Heppenheimer, T.A. Turbulent Skies - The history ofCommercial Aviation

Wiley 1995

Leary, William M. Aerial Pioneers The U.S. Air Mail Service,1918-1927

Smithsonian InstitutionPress

1985

Pratt & Whitney, United Aircraft & Transport Corporation Pratt & Whitney (reprint) 1995Presented by First Annual Report to Stockholders

For the Year Ende3d December 31, 1929

Pratt & Whitney The Pratt & Whitney Aircraft Story Pratt & Whitney 1950Commemoration of the25 year

Smith, Herschel A History of the Aircraft Piston Engine Sunflower University

Press

1986

van der Linden,Robert F.

Airlines & Air Mail: The Post Office and theBirth of the

The University Press ofKentucky

2002

Commercial Aviation Industry

Whitford, Ray Evolution of the Airliner The Crowood Press 2007


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MIKE LAVELLEMuseum of Flight

Seattle, Washington

Mike Lavelle has over 46 years of aviation industry experience in aircraft flightand maintenance operations. Eleven of those years were with the Cessna

Aircraft Company of Wichita Kansas and 24 years with The Boeing Company.

He is now Director of Development with the Museum of Flight in SeattleWashington.

Mike is a FAA flight and ground instructor, as well as a certified Airframe &Powerplant Mechanic. His over 7000 hours flying time include several hundred

hours in vintage aircraft.

With a long time interest in aviation history, he has written papers and madeaviation history presentations to air museums, The Imperial War Museum atDuxford, Branches of the Royal Aeronautical Society in the UK and UnitedStates, as well as, sections of AIAA. He w

boeing model 40 maildelivery airplane

Documents