Waco ZPF6 Words of Recognition
Waco Aircraft Company saw slowly dwindling sales of its open cockpit biplane models as the depression of the 1930’s wore on. This was true of practically all manufacturers who survived into the mid 1930’s as buying airplanes for sport was increasingly impractical given the economic circumstances of the times and the increasing use of closed cockpit airplanes for commercial purposes. Though Waco sold 49 open cockpit biplanes in 1935, including 41 CPF and CPF 1 airplanes to the Brazilian Army and Navy, just two were manufactured in 1936.
Despite slowing sales Waco continued to tweak and improve the “F” model line of aircraft. In late 1935 they introduced the YPF 6 which was powered by a Jacobs 225 horsepower engine. Two of these aircraft were sold. In 1936 they made two more F6 models, designating them as ZPF 6 to indicate being powered by Jacobs 285 horsepower L5 engines. One additional ZPF 6 was manufactured in early 1937 under Approved Type Certificate 586. So, of the 5 F6 models produced two were YPF 6 models from 1935, two were ZPF 6 models from 1936 and one was a 1937 ZPF.
It’s likely that Waco would have stopped producing open cockpit sport planes after 1937 when they made just 9 if the looming war and the creation of the Civilian Pilot Training Program had not come along.
The F6 model serves as a bridge between the earlier sport versions and the later military open cockpit training aircraft. Changes to the F series for the F6 models included a slight widening of the gear tread from 74.5 inches to 77 inches and the addition of a sliding canopy cover for the rear cockpit. The wider gear was later used on the YPT 14 and UPF 7 airplanes up until 1940 when the landing gear was redesigned to the iconic wide design. One other change to the F models with the F6 iteration was the introduction of a smooth cowl to replace the beautiful bump cowl of the F3 and F5 models. At least one of the F6’s, made for Miss Connie Johnson, retained the bump cowl.
Of the five ZPF 6 models produced only one survives as a flying airplane today. That is NC15700, the 1935 Connie Johnson plane, owned by the Western Aviation and Automobile Museum in Hood River, Oregon. There is one 1937 example, NC17470, which is at a museum in Missouri, but it was restored on a UPF 7 chassis and wing set, which is different than the original F6 fuselage and wings, so it is really a marriage of paperwork to convenience.
NC 16579, the aircraft I purchased, is one of two 1936 models and is being restored based on the original Waco drawings for the models made under TCDS #586.
As I set out to collect the entire F model series, I never thought I’d be able to find and buy an F6 due to their rarity. However, Tom Brown who is a restorer and prolific builder of Waco ailerons, was willing to sell his project. I’m excited to have the privilege of restoring it and hope to do so as closely to the original as possible.
Serial number 4378 was manufactured on 9/16/36 and sold to the Department of Revenue for the Commonwealth of Pennsylvania. Originally painted Alexander blue (a dark navy blue) with Vesta yellow funnel striping (a deep golden yellow) and red edging around the stripes, these three colors represent the primary colors of Pennsylvania’s state flag.
Like practically all Waco biplanes in this time period the plane was custom ordered and had a lot of special equipment. To start the front cockpit contained a full suite of instruments including Airspeed, Altimeter, Tachometer, Compass, Bank and Turn Indicator and Vertical Speed. The front cockpit was equipped with a single seat instead of the common two seat arrangement and both cockpits had a heater.
In the rear cockpit the pilot enjoyed an Airspeed Indicator, Altimeter, Tachometer, Compass, Oil temperature and pressure gauges, Vertical Speed Indicator, Rate of Climb and Bank and Turn indicators, Ammeter and Manifold Pressure gauge. The airplane had an electrically heated pitot tube which was very unusual and extra gas tanks for a 73.5-gallon total.
NC 16579 had streamlines (wheel pants), an electric starter, landing lights and provision for a two-way radio. Of course it had the iconic coupe top.
The Jacobs L-5 engine gave the ZPF 6 the fastest top speed of any Waco F model biplane at 156 miles per hour! With a claimed cruising speed of 141 mph it was smoking fast for its time. A provision for landing flares promised help in finding landing fields at night. With all that equipment the plane weighed 1952 pounds and with a gross weight of 2650 pounds there was only 257 pounds left over with a full load of fuel.
Pennsylvania didn’t keep the plane long and sold it to Donald B. Tanner of Bradford, PA on 10/23/39. He in turn sold it less than three years later to Elkins Flying Service of Elkins, West Virginia on 6/29/42 who put it into service in the Civilian Pilot Training Program as a secondary trainer.
Training planes got wrecked frequently and NC 16579 had its engine overhauled and upper wing panels and rudder repaired on 12/14/42 after less than six months’ service. It was in another accident on 7/2/43 and had its propeller repaired but this time by a new owner shown in the FAA’s records as Reliable Flying Service of Northampton, Mass.
Yet another new owner was Georgie R. Galipeau of Northampton shown by 1/13/44 who had the upper wings, struts and rudder from a CPF 1 were installed most likely as the result of another training accident.
The next owner, Interstate Air-parts Incorporated bought the plane on 10/23/45 and moved it to Minneapolis, Mn where they repaired the wings again, installed wheel pants and had a two-seat front seat installed.
On 2/15/46 the plane was sold yet again to North Aviation, Co. of White Bear Lake, MN who purchased and installed skis.
They sold it on 2/25/47 to Bram Air Service Clarion, IA who removed the two landing lights. On 8/21/47 Bram sold to Kenneth Jeffries of Clarion, IA who installed crop dusting equipment manufactured by Mohawk Aircraft Service. No structural members cut or disturbed, but the front controls were removed as the plane was turned into a duster.
Then Aero Dusting of Clear Lake, IA purchased the duster and then on 2/7/49 asked for cancellation of registration because the plane had been scrapped.
John Morozowsky of Zanesville, OH purchased the remains on June 7, 1984, and asked for reinstatement of the registration and then subsequently sold it to Robert Howie, Jr. of Decatur, IL on 4/3/2002. I’m sure Mr. Howie intended to restore the plane, but he never got around to it and in turn sold it to Thomas Brown of Hartford, WI purchased. Tom is an aircraft restorer and prolific builder of Waco ailerons, but he too decided not to restore the plane.
I met Tom at AirVenture on 7/23/24 and purchased the project from him to restore. My goal is to get it back in the air in time for AirVenture 2026 or 2027. If we make that goal, it will have been 78 years since it last flew!
I would have preferred to purchase a completed F6 as that would likely have been much faster, and almost certainly less expensive, than restoring one. Unfortunately, there is really only one “real” F6 in existence and after checking it is not likely to ever come up for sale by its museum owner. That left me with very little likelihood of being able to ever own an F6. I’ve thought about that for the last couple of years and had just about resigned myself to not being able to collect an example of all of the principal F series models.
Waco created the first F model, the RNF/INF/ENF/MNF (wherein the first letter corresponds to the engine installed) in 1930. Subsequently, they introduced the “F2” in 1932, the “F3” in 1934, the “F5” in 1935, the “F6” also in 1935 and ultimately the “F” in 1937. There were various permutations of these numbered models. For example, the VPF 7 is the same airplane as the ZPF 6 but made in 1937 and the YPT 14 is an early version of the UPF 7. The CPF is unusual in that it was made exclusively for the Brazilian Army and Navy (well one example did remain stateside and, as fate would have it, its wings and tail feathers ultimately found there way into my airplane NC 16579). So, there are essentially six Waco F models.
Resigned to only being able to collect 5 of the 6 I set about the restoration of a YMF 5 last year. The only difference, really, between an F3 and an F5 is, well, the designation. They are the same airplane. Originally, there was a difference in the vertical fin but that went away in 1935 when all the F3’s were recalled. So, why bother with one? Well, mine will at least have a different engine!
This all seems a bit silly I realize. In fact, in a recent conversation with a well-known professional restorer he commented, with respect to the ZPF 6 I am restoring “you can put a sliding canopy on a UPF 7” as my friend Les Whittelsey has done. I replied “then you’d have a UPF 7 with a canopy. I want an F6”. And that really is the answer. No one that I am aware of has collected an example of each of these magnificent airplanes. But, even if someone has, I’m fairly confident, since the only owner of an actual F6 doesn’t own an example of all of the rest of them, that no collection today can boast of having one of each example.
So, the answer to “why this ZPF 6” is really twofold. First because I want one. And second because this one is the only one available. This was a rare bird when it was built, and it is rarer still now. When I get this one restored it will be one of two F6’s flying but the only ZPF 6 flying. Just as there are only two UMF 3’s in existence, and mine is the only one flying, the rarity is unusual, and it’s also fun!
Stand by for progress as this bird, like the legendary Phoenix, rises literally from the ashes to fly again. Hopefully soon!
