Was it too much? Too soon? Too late? Too expensive? Or too quickly scuttled?
Isn’t that a great name for this article? And don’t the subtitles stimulate the mind, too? I wish I had thought of them, but I appropriated them from an article written in Business and Commercial Aviation magazine in 1969, twelve years after the scuttling lamented in the article, which is about Cessna’s incredible Model 620 four-engined executive transport created in the mid-1950s and cancelled just on the verge of certification and start of production.
The airplane was unique because it was a small version of the modern airliner of the day, sized to carry half a dozen or so executives in luxury accommodations, above the weather, in pressurized, air conditioned comfort (and with an APU that made it self sufficient and comfy on the ground, too) with airliner safety, speed and range.
But, uniquely, it was designed to operate out of smaller general aviation airports so common around the country. Nothing quite like it had ever been attempted. The author of the article, named Robert Hoffman, became a folk hero to me, because he concluded what I inherently believed: Cessna had made a grievous error in abandoning the concept.
My judgment was subjective, because although I was one of a small cadre of designers that developed the 620 airplane configuration from concept to proof through wind tunnel testing, my career took me far afield and I was no longer following general and business aviation developments. But I just felt for all those twelve years, and actually till now, that the marketing threat that was cited as the primary reason for canceling the 620, that of propeller-driven airliners being replaced by jets in the late 50s and being available to convert to “inexpensive” executive transports, never matured.
But Hoffman’s analysis was still pretty subjective too, and that the 620 project continues to be an item of interest, curiosity and controversy to this day is evidenced by information, or just as likely by misinformation, presented about it on the internet. So the purpose of this article is to quantify Hoffman’s conclusions with data on the 620’s competitors of the period, real and imaginary. Let me set the stage with a historical review of the developments, from a quite personal perspective.
In 1952 Cessna didn’t have different aircraft divisions, and all the preliminary design (PD) work, including that which later resulted in the T-37 AF jet trainer and the Model 620 itself was done by the “company’s” Flight Test, Aerodynamics and Preliminary Design group, in which I worked and in which we all did the things implicit in the group title.
In that year we carried on our differing assignments, which for Preliminary Design efforts mainly meant answering “What if ?” questions for management. The results of a survey conducted by, I believe, the National Business Aircraft Association (today the National Business Aviation Association) came out at that time and provided what I will call a survey specification for the “ideal” airplane business executives said they wanted for their fleets.
In PD we set about to answer the question “What would an airplane that met that spec be like?” and more specifically for management, “Could it potentially be a Cessna product?” By the end of the year we had completed a “preliminary” design of the answer to the business aircraft user’s stated desires. Our design would meet the performance requirements of the survey specification and the flight characteristics requirements of the FAA (then still the CAA).
One of the features that we opted for was four-engine safety, and the use of general aviation engines that allowed low drag profiles for the nacelles. With these small engines, our airplane, later to be named the 620, promised to be relatively inexpensive to operate.
In early 1953 we were instructed to continue the activity as a preliminary design project which meant to us that we should prove our design with a wind tunnel test and explore alternatives for future growth such as a turboprop version and a commuter airline version of the airplane. Since the configuration had the potential of being in airline service, we had to evaluate the differing requirements for certificating to CAA Normal or Transport Category regulations and the effects that would have on the configuration.
Even before the wind tunnel tests were conducted, confidence in the design, and its suitability as a Cessna product, apparently were growing with the company management. Thus the decision to proceed as a regular project was made in the fall of 1953 and a well-known engineering manager in the field, Ralph Harmon, was hired away from Beech to head it.
The wind tunnel test was very successful and our original design continued to be the basis for the airplane that was almost finished with certification in 1957. And as progress continued, Ralph’s M620 program formed the Business Transport Division.
For a time from 1955, my work was totally devoted to the development of the T-37 and for those, then like me, not directly involved with the 620 there was only a strong impression that its program was going really well – impressions supported later by statements by Ralph Harmon that it was the most trouble-free airplane he had ever worked on – and he had worked on a bunch – and by the project’s test pilots that it ranked with the best airplanes they had ever flown (and marveled at manageable control forces without the aid of “boost”).
Thus it was a shock for us to be notified that the 620 Program had been abruptly and completely shut down and its engineers available to be placed elsewhere in the company where there was a need. The explanation given for the termination of the project was that stated above, that it was likely that because of the growing purchase of jet airliners surplus propeller-driven airline transports like the Convair 240 and Martin 202 (and later versions), which could soon be obtained cheaply as surplus and inexpensively converted to executive configurations, would saturate the market for which the M620 was destined.
Apparently the decision to cancel was a traumatic one, with hard feelings created among disputing Cessna senior management, and it was further decided not to ever face it again – calling for the destruction of the prototype and all supporting engineering.
In defense, the decision to stop the 620 was also influenced by a number of secondary factors, all negative, that readers most likely have never heard about. For instance, 1957 was a recession year, with all that means in dampened business expectations. There was the additional prospect that further in the future commercial versions of the Sabreliner and Jetstar executive jet transports would come on the market, and since the initial buys would be subsidized by the government for the military, their pricing might be very attractive. (They of course turned out to be in an entirely different category of performance and cost, and were never a major factor in the market segment in question.)
We were just then ramping up production on the T-37 and it was typical in this phase that government payments were not keeping up with expenditures, creating a short term cash flow problem for the company. And, since the T-37 program was being funded by the government, the 620 represented the largest capital investment Cessna had ever undertaken, and failure would have had corporate wide consequences.
Still, with the certification of the airplane almost complete, and the major concern being one of the prospect, not certainty, of the impact of the converted airliners, might not it have been sensible to at least complete the flight tests and then mothball the airplane for potential resurrection were the conditions found to be different than anticipated? Another concern was that the expected cost, and price, of the 620 had grown beyond that originally estimated, but as will be shown that would only have placed it in the price category of later entrees into the market for which it was designed.
A review of historical data shows three things about what would have happened if the 620 had been continued in the late 50s:
- The prop airliner conversions to executive configurations would not have been decisive (an often overlooked reason may have been that the DOC for the Convairs and Martins was over twice that for the 620 competitors described below).
- Cessna would have had the business for new executive aircraft to itself for five years.
- The company would have been positioned to be a major factor in the executive transport field as that business grew substantially in the years after that. (Of course Cessna redeemed itself with the Citation series of executive jets in the next era of such business aircraft, about a dozen years after the cancellation of the 620.)
Other authors, pursuing their own interests, have provided the information to determine how important propeller airline conversions to executive configurations turned out to be to the sales in that field. These authors researched the history and disposition of every Convair and Martin liner built, and identified those which either started as or were ever converted to executive use. Their history showed that “conversions” took place on an average of one a month, or a total of about 60 units during a five-year period. (Of course if the 620 had been available, it is likely that some of these conversions would not have been done.) Sixty units seems neither a very large nor a very small quantity, not to be ignored but not enough by itself to discourage entry into the field.
For confirmation let us look at it in terms of the airplanes of the same category as the 620 which actually did enter the market at about the time of the end of what I believe would have been the 620’s five years of exclusive command of the market, around 1963. And these airplane companies put their products on the market not against the prospect of the sales of converted Convairs and Martins, but on the reality of what had actually taken place to that date.
In 1961 Interavia magazine published a feature on the number of contenders being entered into the obviously growing executive aircraft market. Their view of suitable airplanes for it extended from the conventional Aero Commander twin to the aforementioned Sabreliner and Jetstar (with twice the speed of the 620 at well over twice the price).
If we concentrate on just those models in the same operating sphere (all weather, pressurized, etc.) and price regime as the 620 (adjusted for inflation to the later date) the list would contain the following – which, with the exception of the cancelled 620, were still not quite ready to be introduced: the Swearingen Merlin II, Mitsubishi-Mooney MU-2, Beech King Air and, on the margin, the Aero Commander Turbo Commander, all twins.
How would the M620 compare to them on price, performance and accommodations? The 620 would be in a virtual tie in price with the most expensive of these, the King Air, which by the way sold more units than the other three less expensive planes put together (thus high price alone was not a market buster). The 620, with in excess of 50% more cabin cross-sectional area than the others, was by far the most spacious and could accommodate one quarter more passengers in the standard configuration. It would tie for having the greatest range, 1700 miles, but at 260 mph only be within the bracket for cruise speeds for these models, which ranged from 250 mph to 280 mph. Another plus, due its four engines, would be its substantially higher engine out service ceiling, 20,000 feet. It would have a longer field length than the others, but still be well in the category of being able to use smaller general aviation airports.
But one thing clouds these comparisons. We’re comparing the reciprocating engined 620 of the 50s to the turboprop-powered competitors of the mid-60s. Undoubtedly the 620 would have been converted to turbines by then, with a bump up in both performance and cost.
Still, collectively over their lives, just these four airplanes directly competitive to the 620 concept accounted for the sale and delivery of over 4,000 units (and obviously prop airliner conversions were a non-starter against these numbers). Given its several important advantages enumerated above, could there be any doubt that the 620 would have sold well beyond the break-even quantity (normally assumed to be 200 to 300 units for Cessna initiatives in those days) in the race for sales with these airplanes? And most importantly for its place in the field, the 620 would have had a five-year jump to establish itself.
Thus the 620 was the Goldilocks of executive aircraft of the time: not too much, not too soon, not too late and not too expensive, but just right. But this Goldilocks was hijacked by its own company’s management on the way to the market.
So, we see that what B/CA’s Hoffman concluded intuitively is substantiated by the facts – Cessna had made a huge mistake. OK, I’m biased because the 620 is one of my all time favorite programs, but in retrospect the airplane did all the original designers, and the industry spec we worked to, asked of it. And it was ready for the very beginning of the developing corporate aircraft market for which it was intended. What a tragedy that it was never allowed to prove itself in the real competitive world.